Study: Weighing The Risks Of MRSA Colonization

MRSA - Photo Credit CDC

# 6807

 

The CDC tells us, in their Definition of MRSA page, that:

 

While 25% to 30% of people are colonized* in the nose with staph, less than 2% are colonized with MRSA (Gorwitz RJ et al. Journal of Infectious Diseases. 2008:197:1226-34.).

*Colonized:
When a person carries the organism/bacteria but shows no clinical signs or symptoms of infection. For Staph aureus the most common body site colonized is the nose.

 

 

Although 2% doesn’t sound like a lot, there are signs that number may be increasing. Once considered primarily a hospital acquired infection, CA-MRSA (community acquired) is growing in incidence.

 

As an example, in Firefighters & Paramedics At Greater Risk Of MRSA and Firefighters & MRSA Revisited we looked at research showing a 10x’s greater incidence of MRSA colonization (20%) among a sampling of firefighters tested in Washington State.

 

Since one person’s colonization can become another person’s infection, topics of debate have included:

 

1. What risks are there to the individual from long-term colonization?
2. What risks are there to others In the Community or a household?
3. What risks are there to others in a hospital or long-term care environment?
4. What (if any) steps should be taken to decolonize carriers, and in what setting (hospital admission? Outpatient?) is decolonization desirable and effective?

 

There are, it seems, few easy answers. 

 

Mary McKenna, editor of the terrific Superbug Blog, took a look at the problems inherent with the decolonization of MRSA carriers in 2009 with:

 

Decolonization: disappointing news 

The upshot was that while studies have shown that decolonization procedures on hospitalized patients about to undergo surgery can reduce infections, the value to other patients is far less clear.

 

And as Maryn points out, overuse of mupirocin – the primary antibiotic used to decolonize patients –can lead to increased resistance over time.

 

And Mary also tells of a paper published in Infection Control and Hospital Epidemiology, that evaluated the success of decolonization protocols in 3 major Illinois hospitals, that less than reassuring results: a temporary reduction in patients’ being colonized with MRSA, but no success in preventing infection.

 

In 2011, the Infectious Diseases Society of America published their clinical practice guidelines for treating MRSA in adults and children, where they endorse `decolonization’, but only under select scenarios (note SSTI = Skin & Soft Tissue Infection):

 

14. Decolonization may be considered in selected cases if:

• i. A patient develops a recurrent SSTI despite optimizing wound care and hygiene measures (C-III).

• ii. Ongoing transmission is occurring among household members or other close contacts despite optimizing wound care and hygiene measures (C-III).

 

• ii. Contacts should be evaluated for evidence of S. aureus infection:
• a. Symptomatic contacts should be evaluated and treated (A-III); nasal and topical body decolonization strategies may be considered following treatment of active infection (C-III).
• b. Nasal and topical body decolonization of asymptomatic household contacts may be considered (C-III)

 

But what, if anything, to do about asymptomatic carriers who are colonized, but not infected with MRSA remains up in the air.

 

Hospital strategies to contain and control MRSA range from passive surveillance to aggressive `search & destroy’ policies – with variations in between.

 

Passive surveillance – which is the most commonly used protocol in the United States – involves  testing only those who have clinical signs or symptoms of
MRSA.

Since patients may be colonized without exhibiting outward signs, this will fail to detect a great many carriers of the bacteria.

Active Surveillance – requires the testing of high risk admissions (ie.  Hx of MRSA, Antibiotic Use, Admission to Hospital in past year, Resident of Long-term care facility, etc.) for the bacteria.

Patients testing positive may be isolated and decolonized or treated, with strict infection control precautions enforced.

Universal Surveillance – takes the above steps to a higher level, where all admissions and personnel are routinely swabbed and tested for MRSA.

“Search & Destroy” – which is the most intensive protocol, has been used successfully in countries like Finland, Denmark and the Netherlands.

It combines Active or Universal Surveillance with testing of patients in high-risk wards at intervals and prior to discharge.

 

The reluctance to adopt the more aggressive of these measures have been the costs, the inconvenience to patients and their visitors, and quite frankly, objections by some hospital staff over being repeatedly tested.

A recent study appearing in Critical Care Medicine, looked at the effects of a strict S&D policy instituted at a rural trauma center, and found an immediate reduction specific types of HAIs (Hospital Acquired Infections) after implementation.

 

Search & Destroy (S&D): Eradication of Mrsa Colonization Is Associated With Decreased Mrsa Infections in Trauma Patients

Borst, Gregory; Waibel, Brett; Toschlog, Eric; Coogan, Michael; Skarupa, David; Rotondo, Michael; Ramsey, Keith

Conclusions: Search and destroy is associated with significant decreases in the incidence of MRSA VAP and CLABSI in trauma patients. Decreases in MRSA CAUTI and wound infections were also seen after the implementation of this program. Pre-emptive strategies to identify and eradicate MRSA are worthwhile endeavors in terms of preventing nosocomial infection.

 

Despite its critics, S&D policies have often shown reductions in HAIs. 

 

Which brings us to another study, published last week in the journal Antimicrobial Agents and Chemotherapy, that finds (among a relatively small cohort of patients) that colonization with MRSA posed a substantial risk of MRSA infection, increased mortality, or readmission to the hospital, compared to patients without MRSA colonization.

 

 

Long-Term Risk for Readmission, Methicillin-resistant Staphylococcus aureus (MRSA) Infection, and Death among MRSA-Colonized Veterans.

Quezada Joaquin NM, Diekema DJ, Perencevich EN, Bailey G, Winokur PL, Schweizer ML.

Source

Division of Infectious Diseases.

Abstract

Background: While numerous studies assessed outcomes of MRSA colonization over the short term, little is known about longer-term outcomes after discharge. An assessment of long-term outcomes could inform the utility of various MRSA prevention approaches.

Methods: A matched cohort study was performed among Veterans Affairs (VA) patients screened for MRSA colonization between the years 2007 and 2009 and followed to evaluate outcomes until 2010. Cox proportional hazard models were used to evaluate the association between MRSA colonization and long-term outcomes such as infection-related readmission, and crude mortality.

Results: 404 veterans were included, 206 of whom were MRSA carriers and 198 who were non-carriers. There were no culture-proven MRSA infections on readmission among the non-carriers, but 13% of MRSA-carriers were readmitted with culture proven MRSA infections on readmission (P<0.01).

MRSA carriers were significantly more likely to be readmitted, be readmitted more than once due to proven or probable MRSA infections, and be readmitted within 90 days of discharge compared to non-carriers (p<0.05). Infection-related readmission (adjusted hazard ratio [AHR] =4.07; 95% confidence interval [CI]: 2.16, 7.67) and mortality (AHR=2.71; 95% CI: 1.87, 3.91) were significantly higher among MRSA carriers compared to non-carriers, after statistically adjusting for potential confounders.

Conclusions: Among a cohort of VA patients, MRSA carriers are at high risk of infection-related readmission, MRSA infection and mortality compared to non-carriers. Non- carriers are at very low risk of subsequent MRSA infection. Future studies should address whether interventions such as nasal or skin decolonization could result in improved outcomes for MRSA carriers.

Although based on a small cohort, this study suggests that being colonized (but not infected) with MRSA is a significant risk factor for future infection, and if these findings can be confirmed by others, may influence how MRSA colonization is viewed in the future.

 

Despite some recent improvements in MRSA rates among hospitalized patients in the United States, HAIs (which include many other pathogens) continue to exact a heavy toll. This oft quoted assessment from the CDC on the burden of Hospital Acquired Infections in the United States is from 2010.

 

A new report from CDC updates previous estimates of healthcare-associated infections. In American hospitals alone, healthcare-associated infections account for an estimated 1.7 million infections and 99,000 associated deaths each year. Of these infections:

• 32 percent of all healthcare-associated infection are urinary tract infections
• 22 percent are surgical site infections
• 15 percent are pneumonia (lung infections)
• 14 percent are bloodstream infection

For more on MRSA, and many other antibiotic-resistant threats, you can do no better than to visit Maryn McKenna’s terrific Superbug Blog, and to read her book Superbug: The Fatal Menace of MRSA . . . which won last year’s  NASW Science in Society Journalism Award.

You’ll find my review of her book HERE

»» Read More

Study: MRSA In Waste Water Treatment Plants

 

Photo Credit USGS – Wastewater: The Primary Treatment Process

1. Screening 2. Pumping 3. Aerating 4. Removing sludge 5. Removing Scum 6. killing bacteria

 

 

# 6699

 

While it may not seem (or even be) glamorous, there are scientists who spend considerable time examining the input and output of wastewater (sewage) treatment plants. Given the potential environmental impact of the discharges from these facilities, it is important work.

 

The subject of wastewater treatment plants - and the substances that their processes can fail to remove during treatment - has come up before in this blog.

 

In 2007, with governments around the world stockpiling large quantities of Tamiflu (Oseltamivir) in anticipation of a pandemic, concerns turned to what would happen if millions of doses were dispensed, consumed, and excrete by humans into the waste water system in a short period of time.

 

In The Law of Unintended Consequences we looked at a report in Environmental Health Perspectives (EHP) called Potential Risks Associated with the Proposed Widespread Use of Tamiflu that found enough of excreted oseltamivir carboxylate (OC) would survive treatment, and be ejected into the environment, to raise concerns.

 

In October of 2009 and we saw another report (see Everything Old Is News Again), based on studies done the previous year in Kyoto, Japan – that showed elevated levels of the OC Metabolite in wastewater discharge. 

 

In 2011, in Pandemics & The Law Of Unintended Consequences we saw yet another study that looked at potential problems inherent in the massive distribution and consumption of antibiotics and antivirals during a pandemic.

 

WWTPs (Wastewater Treatment Plants) depend upon microbial activity in order to breakdown or `digest’ sewage.

 

Antibiotics in the sewage – at elevated levels such as might be seen during a pandemic – could inhibit microbial activity, resulting in the failure of WWTPs and the discharge of under-treated wastewater into the environment.

 

Today, a new study, this time on MRSA (methicillin-resistant Staphylococcus aureus) and how it fares in the wastewater treatment process. As many WWTPs provide reclaimed water for irrigation use, the concern is that MRSA shed in feces might make it through the plant and into the environment.

 

The University of Maryland-led study study appears as an open access article that appears in Environmental Health Perspectives. 

Methicillin-Resistant Staphylococcus aureus (MRSA) Detected at Four U.S. Wastewater Treatment Plants

November 1, 2012 Research 

Rachel E. Rosenberg Goldstein, Shirley A. Micallef, Shawn G. Gibbs, Johnnie A. Davis, Xin He, Ashish George, Lara M. Kleinfelter, Nicole A. Schreiber, Sampa Mukherjee, Amir Sapkota, Sam W. Joseph, and Amy R. Sapkota

Abstract

Background: The incidence of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) infections is increasing in the United States, and it is possible that municipal waste­water could be a reservoir of this micro­organism. To date, no U.S. studies have evaluated the occurrence of MRSA in waste­water.

 

Objective: We examined the occurrence of MRSA and methicillin-susceptible S. aureus (MSSA) at U.S. waste­water treatment plants.

 

Methods: We collected waste­water samples from two Mid-Atlantic and two Midwest waste­water treatment plants between October 2009 and October 2010. Samples were analyzed for MRSA and MSSA using membrane filtration. Isolates were confirmed using biochemical tests and PCR (polymerase chain reaction). Antimicrobial susceptibility testing was performed by Sensititre® micro­broth dilution. Staphylococcal cassette chromosome mec (SCCmec) typing, Panton-Valentine leucocidin (PVL) screening, and pulsed field gel electrophoresis (PFGE) were performed to further characterize the strains. Data were analyzed by two-sample proportion tests and analysis of variance.

 

Results: We detected MRSA (n = 240) and MSSA (n = 119) in 22 of 44 (50%) and 24 of 44 (55%) waste­water samples, respectively. The odds of samples being MRSA-positive decreased as treatment progressed: 10 of 12 (83%) influent samples were MRSA-positive, while only one of 12 (8%) effluent samples was MRSA-positive. Ninety-three percent and 29% of unique MRSA and MSSA isolates, respectively, were multi­drug resistant. SCCmec types II and IV, the pvl gene, and USA types 100, 300, and 700 (PFGE strain types commonly found in the United States) were identified among the MRSA isolates.

 

Conclusions: Our findings raise potential public health concerns for waste­water treatment plant workers and individuals exposed to reclaimed waste­water. Because of increasing use of reclaimed waste­water, further study is needed to evaluate the risk of exposure to antibiotic-resistant bacteria in treated waste­water.

 

Environ Health Perspect 120:1551–1558 (2012). http://dx.doi.org/10.1289/ehp.1205436 [Online 6 September 2012]

Full PDF FILE

 

 

The full report runs 8 pages, and can be download here.

A summation of this research is available from the University of Maryland’s School of Public Health. I’ve cut to the chase with the excerpts  posted below, so follow the link to read the full story.

 

The School of Public Health News

November 5, 2012
NEWS RELEASE
Contact: Kelly Blake, kellyb@umd.edu, 301-405-9418

Superbug MRSA Identified in U.S. Wastewater Treatment Plants

University of Maryland-led study is first to document environmental source of the antibiotic-resistant bacteria in the United States

<SNIP>

They found that MRSA, as well as a related pathogen, methicillin-susceptible Staphylococcus aureus (MSSA),were present at all four WWTPs, with MRSA in half of all samples and MSSA in 55 percent.MRSA was present in 83 percent of the influent-- the raw sewage--at all plants, butthe percentage of MRSA- and MSSA-positive samples decreased as treatment progressed. Only one WWTP had the bacteria in the treated water leaving the plant, and this was at a plant that does not regularly use chlorination, a tertiary step in wastewater treatment.

 

Ninety-three percent of the MRSA strains that were isolated from the wastewater and 29 percent of MSSA strains were resistant to two or more classes of antibiotics, including several that the U.S. Food and Drug Administration has specifically approved for treating MRSA infections. At two WWTPs, MRSA strains showed resistance to more antibiotics and greater prevalence of a gene associated with virulence at subsequent treatment stages, until tertiary chlorination treatment appeared to eliminate all MRSA. This suggests that while WWTPs effectively reduce MRSA and MSSA from influent to effluent, they may select for increased antibiotic resistance and virulence, particularly at those facilities that do not employ tertiary treatment (via chlorination).

 

“Our findings raise potential public health concerns for wastewater treatment plant workers and individuals exposed to reclaimed wastewater,” says Rachel Rosenberg Goldstein, environmental health doctoral student in the School of Public Health and the study’s first author. “Because of increasing use of reclaimed wastewater, further research is needed to evaluate the risk of exposure to antibiotic-resistant bacteria in treated wastewater.”

(Continue . . . )

 

Most WWTPs are designed to efficiently remove solids and to disinfect discharge water, but do less well when it comes to removing chemicals.

 

Although only four plants were studied in this project, the results suggest that plants that fail to chlorinate routinely may be at greater risk of letting antibiotic resistant bacteria back into the environment. 

 

Whether it is antiviral or antibiotic metabolites, remnants from  illicit drug use, or resistant organisms themselves, what comes out of these treatment plants can affect our environment, and our population.

 

On a planet with 7 billion people, figuring out how to safely dispose of, recycle, or treat human waste has become a major challenge.

 

Shortcomings in WWTP systems – even seemingly small ones - can pose serious public health risks, including potentially creating and spreading resistant bacterial organisms.

 

As the authors of this study concluded, more research is now needed to evaluate and quantify the risk.

»» Read More

The Flight Of The Bacterial Intruder

Credit CDC PHIL

 

 

# 6625

 

HCAIs (Health care associated Infections) or HAIs (Hospital acquired infections) constitute a major threat to life, health, and the cost of medical care in this country, and around the world. This oft quoted assessment from the CDC on the burden of Hospital Acquired Infections in the United States is from 2010.

 

A new report from CDC updates previous estimates of healthcare-associated infections. In American hospitals alone, healthcare-associated infections account for an estimated 1.7 million infections and 99,000 associated deaths each year. Of these infections:

• 32 percent of all healthcare-associated infection are urinary tract infections
• 22 percent are surgical site infections
• 15 percent are pneumonia (lung infections)
• 14 percent are bloodstream infections

 

A 2009 report The Direct Medical Costs of Healthcare-associated Infections in U.S. Hospitals and the Benefits of Prevention finds:

 

Applying two different Consumer Price Index
(CPI) adjustments to account for the rate of inflation in hospital resource prices, the overall annual direct medical costs of HAI to U.S. hospitals ranges from $28.4 to $33.8 billion (after adjusting to 2007 dollars using the CPI for all urban consumers) and $35.7 billion to $45 billion (after adjusting to 2007 dollars using the CPI for inpatient hospital services).

 

 

As you can imagine, hospitals are engaged in a perpetual battle against the spread of infection - and while progress is being made - many pathogens continue to slip past the infection control safeguards.

 

A study from the University of Leeds recently published in the Journal Building and Environment may provide a clue as to why the infection control measures being used today have failed to curb the spread of bacteria in the hospital setting.

 

 

Bioaerosol Deposition in Single and Two-Bed Hospital Rooms: A Numerical and Experimental Study

M.F. King, C.J. Noakes, P.A. Sleigh, M.A. Camargo-Valero

 

You’ll find the abstract, along with figures and tables from this article, at the link above. But the full paper is behind a pay wall. The University of Leeds website, however, has a synopsis of this research project, which is excerpted below:.

 

 

Superbugs ride air currents around hospital wards

Published Thursday 11th October 12

Hospital superbugs can float on air currents and contaminate surfaces far from infected patients’ beds, according to University of Leeds researchers.

 

The results of the study, which was funded by the Engineering and Physical Sciences Research Council (EPSRC), may explain why, despite strict cleaning regimes and hygiene controls, some hospitals still struggle to prevent bacteria moving from patient to patient.

 

It is already recognised that hospital superbugs, such as MRSA and C-difficile, can be spread through contact. Patients, visitors or even hospital staff can inadvertently touch surfaces contaminated with bacteria and then pass the infection on to others, resulting in a great stress in hospitals on keeping hands and surfaces clean.

 

But the University of Leeds research showed that coughing, sneezing or simply shaking the bedclothes can send superbugs into flight, allowing them to contaminate recently-cleaned surfaces.

 

PhD student Marco-Felipe King used a biological aerosol chamber, one of a handful in the world, to replicate conditions in one- and two-bedded hospital rooms. He released tiny aerosol droplets containing Staphyloccus aureus, a bacteria related to MRSA, from a heated mannequin simulating the heat emitted by a human body. He placed open Petri dishes where other patients’ beds, bedside tables, chairs and washbasins might be and then checked where the bacteria landed and grew.

 

The results confirmed that contamination can spread to surfaces across a ward. “The level of contamination immediately around the patient’s bed was high but you would expect that. Hospitals keep beds clean and disinfect the tables and surfaces next to beds,” said Dr Cath Noakes, from the University’s School of Civil Engineering, who supervised the work. “However, we also captured significant quantities of bacteria right across the room, up to 3.5 metres away and especially along the route of the airflows in the room.”

 

“We now need to find out whether this airborne dispersion is an important route of spreading infection,” added co-supervisor Dr Andy Sleigh.

(Continue . . .)

 

 

While we often think first of viruses when it comes to airborne transmission of illness, some types of bacteria (e.g. Legionella, Mycoplasma pneumonia, Tuberculosis) are easily aerosolized and transmitted.

 

This study is not the first to identify the airborne spread of Staphylococcus aureus, but they have developed an ingenious way to quantify it.

 

Regarding MRSA and C. Difficile the Journal of The Royal Society published a review in 2009 called:

 

Airborne transmission of disease in hospitals

I. Eames, J. W. Tang,Y. Li and P. Wilson

(EXCERPT)

MRSA can survive on surfaces or skin scales for up to 80 days and spores of Clostridium difficile may last even longer. MRSA can be transmitted in aerosol from the respiratory tract but commonly attaches to skin scales of various sizes. The distance of travel depends on the size of the scale, the larger falling to the floor within 1–2 m, the smaller travelling the entire length of the ward.

<SNIP>

Clostridium difficile spores are thought to spread in the air and can be found near a patient carrying the organism (Roberts et al. 2008). However, unlike MRSA, they are rarely isolated from air samples.

 

 

Not surprisingly, in 2010, we saw a study published in the AJIC: American Journal of Infection Control that found that the more roommates you have during a hospital stay, the greater chance you will have of contracting an HAI like MRSA or C. Diff.

 

Exposure to hospital roommates as a risk factor for health care–associated infection

Meghan Hamel, MSc, Dick Zoutman, MD, FRCPC, Chris O'Callaghan, DVM, MSc, PhD

 

The authors used this study to promote the idea  of making private (or at least, semi-private) rooms the norm in Canadian hospitals. While acknowledging that it would involve considerable up-front costs, they believe the long-term savings would be considerable.

 

All of this highlights the great challenges involved in substantially reducing the incidence of HAIs in our health care facilities.

 

Solutions must not only include stringent hand hygiene and improved cleaning methods, but engineering solutions as well.

 

For more on the prevention of Hospital Acquired Infections you may wish to visit the CDC’s HAI PAGE.

 

 

Or revisit some of these earlier blogs on hospital acquired infections.

 

HPA: Healthcare-Associated Infection (HCAI) Survey

A Barrier To Good Hand Hygiene

Study: Hospital Uniforms And Bacteria

Study: HAIs, Universal Surveillance, & MRSA

 

And finally, the subject of HAIs is often addressed by Maryn McKenna on her excellent Superbug Blog, and was a major focus of her book SUPERBUG: The Fatal Menace Of MRSA.

 

Both are highly recommended.

»» Read More

McKenna On MRSA Pneumonia Cluster In Maryland

 

 

Clumps of methicillin-resistant Staphylococcus aureus Magnified 2390x. – Credit CDC PHIL

# 6211

 

Author, journalist, and blogger Maryn McKenna is Flublogia’s resident expert on everything antimicrobial resistant, and is the author of Superbug: The Fatal Menace of MRSA.

 

This morning she has written about the cluster of flu-related deaths in Calvert County Maryland that has captured out attention this week.

 

Yesterday, new details emerged that suggest that a form of MRSA (or necrotizing) pneumonia served as a deadly co-infection in these deaths (see CIDRAP: MRSA Pneumonia Suspected In Calvert County Flu Cluster).

 

While we await further lab and autopsy results on this unusual and tragic story, Maryn gives us the short course in this emerging, and often lethal, complication of flu.

 

 

 

Flu Infections And MRSA Deaths In Maryland

• By Maryn McKenna March 9, 2012 | 

»» Read More

CIDRAP: MRSA Pneumonia Suspected In Calvert County Flu Cluster

 

Clumps of methicillin-resistant Staphylococcus aureus – Credit CDC PHIL

# 6210

 

 

Although we haven’t seen any official updates since late yesterday afternoon, reports have been trickling in through various media outlets suggesting that the fatal flu cluster in Lusby, Md.  involved the seasonal H3N2 virus and an aggressive form of MRSA pneumonia.

 

Lisa Schnirring of CIDRAP News  brings us up to date this evening with this report.  Follow the link to read her report in its entirety.

 

 

MRSA pneumonia suspected in fatal flu cluster

Lisa Schnirring Staff Writer

Mar 8, 2012 (CIDRAP News) – Another family member linked to a fatal flu cluster in Calvert County, Md., has been hospitalized, as suspicion grew that an aggressive drug-resistant form of pneumonia may have played a role in the severe illnesses, according to media reports.

 

Maryland and Calvert County health officials didn't report any new details about the cases, but the Washington Post reported yesterday that the sister of the 81-year-old woman who died has been hospitalized at MedStar Washington Hospital Center with fever but no other flu symptoms.

(Continue . . . )

 

 

Tissues taken during autopsies from two of the victims have reportedly been sent to the CDC for further analysis, which can take a day or two to complete.

»» Read More

McKenna: Man Vs. MRSA

 

 

# 6115

 

Among the many fascinating topics Maryn McKenna covered in her book Superbug: The Fatal Menace of MRSA was the possibility that a vaccine might someday be developed against this growing epidemic of antibiotic resistant staph.

 

 

 

 

Today, Maryn follows up with a terrific feature that appears in the prestigious Journal Nature, which focuses on Robert Daum, the founder of the University of Chicago's MRSA Research Center, and others who are in search of this as-yet elusive goal.

 

Follow the link to read:

 

Vaccine development: Man vs MRSA

For decades, Robert Daum has studied the havoc wreaked by methicillin-resistant Staphylococcus aureus. Now he thinks he can stop it for good.

• Maryn McKenna

01 February 2012

»» Read More

The Passing Parade Of 2011 – Pt. 2

 

 

 

# 6036

 

Over the past year I’ve posted more than 900 blogs, dozens of which looked at some of the latest research into influenza and other emerging infectious diseases.

 

Since these studies oft times make an initial splash only to get lost in the passing parade of new reports, today I’ve some brief summaries (with links back to the original blogs) on some of the research of 2011 I believe is deserving of a second look.

 

This is the second such roundup, the first one may be accessed at this link.

 

 

Last April in Lancet Study: NDM-1 In New Delhi Water Supply, we saw a report authored by Timothy Walsh, Janis Weeks , David M Livermore, and Mark A Toleman that looked for – and found – bacteria carrying the NDM-1 enzyme in New Delhi's drinking water supply.

 

We’ve a press release on this study, issued by Cardiff University, that gives the highlights of the research, but the `money quote’ (emphasis mine) buried about halfway down is:

 

Resistant bacteria were found in 4 per cent of the water supplies and 30 per cent of the seepage sites. The researchers identified 11 new species of bacteria carrying the NDM-1 gene, including strains which cause cholera and dysentery.

 

Below is a link to the Lancet study, which you can read in its entirety (a free registration is required).

 

 

The Lancet Infectious Diseases, Early Online Publication, 7 April 2011

doi:10.1016/S1473-3099(11)70059-7

Dissemination of NDM-1 positive bacteria in the New Delhi environment and its implications for human health: an environmental point prevalence study

Prof Timothy R Walsh PhD , Janis Weeks BS, David M Livermore PhD , Mark A Toleman PhD

 

Again in April, we saw research seeking to answer the question over why there was such a wide variance in death rates around the world with the 1918 Spanish influenza. 

 

In 2006, in a Lancet journal (doi:10.1016/S0140- 6736(06) 69895-4) article cited as much as a 30-fold difference in mortality rates around the world:

 

Estimation of potential global pandemic influenza mortality on the basis of vital registry data from the 1918—20 pandemic: a quantitative analysis

Christopher JL Murray , Alan D Lopez , Brian Chin , Dennis Feehan , Kenneth H Hill

Excess mortality ranged from 0·2% in Denmark to 4·4% in India. Since there was some under-registration of mortality in India, total pandemic mortality could have been even higher.

 

 

This wide disparity in mortality rates – much of it based on anecdotal accounts – has long intrigued researchers.  This new study from the Norwegian Institute of Public Health that attempts to answer some of these questions.

 

What they found was that the mortality rate varied nearly 100 fold between remote, rural regions and urban populations, and that in the more remote areas, older persons were just as susceptible to the virus as those who were younger.

 

This study appears in the Journal Epidemics.

Geography May Explain Adult Mortality from the 1918–20 Influenza Pandemic

Original Research Article
Pages 46-60
Svenn-Erik Mamelund

 

The theory that a similar H1 virus circulated prior to 1890 – and that provided some immunity to those over the age of 30 – is bolstered by this study.

 

 

Given the current flap over the H5N1 experiments conducted by Ron Fouchier in the Netherlands and Yoshihiro Kawaoka  at the University of Wisconsin (see The Biosecurity Debate On H5N1 Research) the next two studies deserve a second look as well.

 

 

Simplified Illustration of a Serial Passage Experiment. 

 

In H5N1: A Rite Of Passage we looked at how serial passage studies are conducted, and at one in particular that appeared in the Journal of Animal and Veterinary Advances that looked at increases in pathogenicity (in mice) of two H5N1 viruses after six serial passages in quail.

 

The study is called:

 

The Pathogenicity Variation of Two Quail-Origin H5N1 HPAV to BALB/c Mice after Six Passages in Quail

Hailiang Sun, Peirong Jiao, Yuqiang Cheng, Runyu Yuan, Pengfei Cui, Liming Jin, Chaoan Xin and Ming Liao

 

Another study, profiled in PNAS: Reassortment Potential Of Avian H9N2, looked at the reassortment potential of the avian H9N2 virus and H1N1. Research was done using ferrets whose respiratory physiology is considered relatively close to humans.

 

Compatibility of H9N2 avian influenza surface genes and 2009 pandemic H1N1 internal genes for transmission in the ferret model

J. Brian Kimble, Erin Sorrell,  Hongxia Shao,  Philip L. Martin, and Daniel Roberto Perez

 

(Excerpt from the abstract)

Four reassortant viruses were generated, with three of them showing efficient respiratory droplet transmission. Differences in replication efficiency were observed for these viruses; however, the results clearly indicate that H9N2 avian influenza viruses and pH1N1 viruses, both of which have occasionally infected pigs, have the potential to reassort and generate novel viruses with respiratory transmission potential in mammals.

 

 

The entire study is available online, and open access.

 

 

And in Study: Prior Antibiotic Use & MRSA In Children Canadian researchers, examining 13 years worth of data from the UK’s General Practice Research Database (GPRD), came up with what they called  a `robust association’ between a prior history of antibiotic use and rates of CA-MRSA (Community Acquired Methicillin Resistant Staph Aureus) infection in children.

The study appeared Aug. 1st  in the Archives of Pediatrics & Adolescent Medicine.

 

Antibacterial Drugs and the Risk of Community-Associated Methicillin-Resistant Staphylococcus aureus in Children

Verena Schneider-Lindner, MD, MSc; Caroline Quach, MD, MSc; James A Hanley, PhD; Samy Suissa, PhD

Arch Pediatr Adolesc Med. Published online August 1, 2011. doi:10.1001/archpediatrics.2011.143

 

What these researchers found was that while nearly half of children with MRSA in this study had no recent history of antibiotic use, the adjusted relative risk (RR) of developing MRSA was 3.5 times higher among children who had received antibiotic treatment in the previous 30-180 days before infection.

 

And that relative risk increased substantially among children who received more than one course of antibiotics.

 

To find more blogs specific to research you can use the RESEARCH quick link on my sidebar.

 

As news is often slow during the holiday season, over the next couple of weeks I plan to post one or two more retrospectives on the news and research of the year that was.

»» Read More

Study: Kids, Pandemic H1N1 & MRSA Co-Infection

 

 

 

# 5945

 

We’ve looked at a connection between enhanced flu mortality and bacterial co-infections many times in the past, most recently last September in mBio: Lethal Synergism of H1N1 Pandemic Influenza & Bacterial Pneumonia.

 

In that study scientists at NIAID and the Institute for Systems Biology (ISB) infected experimental mice with both seasonal flu and the 2009 H1N1 pandemic flu, and after 48 hours exposed some of them to Streptococcus pneumoniae, one of the main causes of pneumonia.

 

Mice that were exposed only to the two flu strains showed expected flu symptoms, but all survived.

 

Mice that were exposed to seasonal flu and S. pneumoniae experienced minor lung damage, but once again, all survived.

 

But all of the mice infected with the pandemic H1N1 virus, and S. pneumoniae showed severe weight loss, lung damage, and 100% mortality

 

Indicating that pandemic H1N1, more than seasonal flu, exacerbated an S. pneumoniae co-infection.

 

In 2008, we saw a study in The Journal of Infectious Diseases by Morens, Taubenberger, and Fauci that looks at the role of bacterial pneumonia in the high death toll of 1918 (see Viral-Bacterial Copathogenesis).

 

An excerpt from their study reads:

 

Conclusions. The majority of deaths in the 1918–1919 influenza pandemic likely resulted directly from secondary bacterial pneumonia caused by common upper respiratory–tract bacteria.

 

Less substantial data from the subsequent 1957 and 1968 pandemics are consistent with these findings. If severe pandemic influenza is largely a problem of viral-bacterial copathogenesis, pandemic planning needs to go beyond addressing the viral cause alone (e.g., influenza vaccines and antiviral drugs).

 

2008 also saw additional studies published in the CDC’s EID Journal that looked at the synergy between pandemic flu and bacterial pneumonia, including:

 

Brundage JF, Shanks GD. Deaths from bacterial pneumonia during 1918–19 influenza pandemic. Emerg Infect Dis. 2008 Aug;

 

Ravindra K. Gupta,*  Robert George, and Jonathan S. Nguyen-Van-Tam Bacterial Pneumonia and Pandemic Influenza Planning Emerg Infect Dis. 2008 Aug;

 

Shanks and Brundage found, for instance, that during the 1918 pandemic 5% of the deaths attributed to the 1918 pandemic occurred in the first 3 days of infection, while the median time from illness onset to death was 7–10 days, with many deaths occurring >2 weeks after initial symptoms..

 

Which they believed was more indicative of death due to secondary bacterial infection than directly from a flu virus, or a cytokine storm response (see Influenza's One-Two Punch).

 

These studies, along with a number of others, have enforced the idea that pneumococcal vaccines like PCV7 Pneumococcal Vaccine Would Save Lives In A Pandemic.

 

Given this past research, it shouldn’t come as a terrible surprise that a study that appears today in the journal Pediatrics found, among other things, that a co-infection with MRSA was associated with a higher mortality rate among healthy kids infected with the 2009 H1N1 pandemic virus.

 

First a link to the study, and an excerpt from the abstract, then I’ll be back with more.

 

Critically Ill Children During the 2009–2010 Influenza Pandemic in the United States

Adrienne G. Randolph,Frances Vaughn, Ryan Sullivan, Lewis Rubinson, B. Taylor Thompson, Grace Yoon, Elizabeth Smoot, Todd W. Rice, Laura L. Loftis, Mark Helfaer,Allan Doctor, Matthew Paden, Heidi Flori, Christopher Babbitt, Ana Lia Graciano, Rainer Gedeit, Ronald C. Sanders, John S. Giuliano, Jerry Zimmerman, Timothy M. Uyeki

(EXCERPT)

Overall, 71 (8.5%) of the patients had a presumed diagnosis of early (within 72 hours after PICU admission) Staphylococcus aureus coinfection of the lung with 48% methicillin-resistant S aureus (MRSA). In multivariable analyses, preexisting neurologic conditions or immunosuppression, encephalitis (1.7% of cases), myocarditis (1.4% of cases), early presumed MRSA lung coinfection, and female gender were mortality risk factors. Among 251 previously healthy children, only early presumed MRSA coinfection of the lung (relative risk: 8 [95% confidence interval: 3.1–20.6]; P < .0001) remained a mortality risk factor.

Conclusions: Children with preexisting neurologic conditions and immune compromise were at increased risk of pH1N1-associated death after PICU admission. Secondary complications of pH1N1, including myocarditis, encephalitis, and clinical diagnosis of early presumed MRSA coinfection of the lung, were mortality risk factors.

 

The entire study is behind a pay wall, but we’ve a lengthy press release available with considerable detail.

 

Why Did Healthy Children Fall Critically Ill in the 2009 H1N1 Flu Pandemic?

Largest study to date finds co-infection with MRSA increased death risk 8-fold; flu vaccination urged

 

BOSTON, Nov. 7, 2011 /PRNewswire-USNewswire/ -- During the 2009 H1N1 influenza pandemic, many previously healthy children became critically ill, developing severe pneumonia and respiratory failure, sometimes fatal. The largest nationwide investigation to date of influenza in critically ill children, led by Children's Hospital Boston, found one key risk factor: Simultaneous infection with methicillin-resistant Staphylococcus aureus (MRSA) increased the risk for flu-related mortality 8-fold among previously healthy children.

 

Moreover, almost all of these co-infected children were rapidly treated with vancomycin, considered to be appropriate treatment for MRSA. The fact that they died despite this treatment is especially alarming given the rising rates of MRSA carriage among children in the community.

 

"There's more risk for MRSA to become invasive in the presence of flu or other viruses," says study leader Adrienne Randolph, MD, MsC, of the Division of Critical Care Medicine at Children's Hospital Boston. "These deaths in co-infected children are a warning sign."

 

The researchers hope their findings, published November 7 by the journal Pediatrics, (eFirst pages) will promote flu vaccination among all children aged 6 months and older. (No flu vaccine is currently available for children younger than 6 months.)

 

(Continue . . . )

 

As we’ve discussed before, a small percentage of the population is known to carry either MRSA or non-resistant S. aureus in their nasal cavities.

 

This from the CDC:

Definition of MRSA

 

While 25% to 30% of people are colonized* in the nose with staph, less than 2% are colonized with MRSA (Gorwitz RJ et al. Journal of Infectious Diseases. 2008:197:1226-34.).

*Colonized:
When a person carries the organism/bacteria but shows no clinical signs or symptoms of infection. For Staph aureus the most common body site colonized is the nose.

 

While 2% doesn’t sound like a lot, there are signs that number may be increasing. Once considered primarily a hospital acquired infection, CA-MRSA (community acquired) is growing in incidence.

 

For instance, In Firefighters & Paramedics At Greater Risk Of MRSA and Firefighters & MRSA Revisited we looked at research showing a 10x’s greater incidence of MRSA colonization (20%) among a sampling of firefighters tested in Washington State.

 

Most of the time our immune systems keep these bacteria in check, and we display no outward signs of infection.

 

But when our immune systems are weakened, such as when we are stricken by influenza, these resistant bacteria can suddenly bloom and become invasive.

 

Again, from the Press Release:

 

Influenza appears to suppress the immune response, making children who are already colonized more susceptible to invasive bacterial disease.

 

"Previously, MRSA has not been considered a common cause of pneumonia in kids but this may be changing," Randolph says. "It's likely that flu and other viral infections let MRSA invade and that there's some synergistic reaction between flu and these bacteria."

 

While this study specifically links MRSA to bad outcomes among children with pandemic H1N1, the 2008 study by Shanks and Brundage found that during the 1918 pandemic:

 

. . .  the bacteria most often recovered from the sputum, lungs, and blood of pneumonia patients, alive or dead, were common colonizers of the upper respiratory tracts of healthy persons, i.e., Hemophilus influenzae, Streptococcus pneumoniae, S. pyogenes, and/or Staphylococcus aureus.

 

Whether it is the routine carriage of bacteria in our respiratory system, or the make up of the microflora in our gut biome, scientists are increasingly linking our health, and the progression and outcome of some diseases, to our individual body’s ecosystem.

 

Which may explain, at least partially, why 99 out of 100 people can catch the flu and recover quickly and without incident, while an unlucky 1% may endure a serious and sometimes fatal illness.

 

The authors of today’s study advise:

 

Physicians seeing children with serious lower-respiratory-tract disease during flu season are urged to give early antiviral treatment (Tamiflu or zanamivir [Relenza]) and antibiotics covering MRSA and other flu-associated bacteria, even before suspected infections are confirmed in the lab, the researchers say.

 

But other approaches are urgently needed. "MRSA is hard to develop a vaccine against – researchers have been trying since the 1960s and have been unsuccessful," says Randolph. "So the only way to prevent these severe complications is to get everyone vaccinated against the flu, and do more studies of MRSA colonization so we can prevent it in the community and in kids."

 

Further evidence, as if we needed it, that influenza and its complications can be complex, difficult, and occasionally deadly foes.

»» Read More

World MRSA Day: October 1st, 2011

 

 

 

# 5872

 

 

While some reductions in the spread of Hospital Acquired Infections (HAIs) have been reported in the past couple of years, MRSA remains a serious public health threat and is increasingly is being found outside the hospital environment.

 

Although the true burden is likely higher, in 2008 the ABCs (Active Bacterial Core Surveillance) report estimated that MRSA was responsible for nearly 90,000 serious infections and more than 15,000 deaths in the United States each year.

 

In 2009, Jeanine Thomas - who created the MRSA Survivors Network - pushed for the creation of World MRSA Day, and this year that observance is set for October 1st.

 

This year, the global theme is "The MRSA Epidemic - A Call to Action.", and the kickoff event will be live-streamed from Loyola University on the internet tomorrow morning. 

 

 

 

World MRSA Day Event to Broadcast Live - October 1, 2011

CHICAGO, Sept. 7, 2011 /PRNewswire via COMTEX/ -- The third annual World MRSA Day kickoff event and Global MRSA Summit at Loyola University Stritch School of Medicine in Maywood, Illinois on October 1, 2011 will broadcast live via web stream starting at 10:30 a.m. central time and can be viewed at www.worldmrsaday.org and www.MRSAsurvivors.org . The event is open to the public, free of charge and entire families are encouraged to attend.

(Continue . . . )

 

 

More details are available from the World MRSA Day website, including a couple of video PSAs, and link to the webcast.

 

• World MRSA Day Webcast

  Please watch the World MRSA Day kickoff event webcast live!

• 
  

 

 

For more on MRSA, and many other antibiotic-resistant threats, you can do no better than to visit Maryn McKenna’s terrific Superbug Blog, and to read her book Superbug: The Fatal Menace of MRSA . . . which recently won this year’s  NASW Science in Society Journalism Award.

 

You’ll find my review of her book HERE.

»» Read More

Study: Hospital Uniforms And Bacteria

 

 

Photo Credit CDC PHIL 

 

# 5798

 

 

HAIs, or Hospital Acquired Infections, take an incredible toll on patient’s health and our health care system every year. 

 

According to the HHS, they rank among the top ten leading causes of death in the United States, and accounted for an estimated 1.7 million infections and 99,000 associated deaths in 2002.

 

While hospitals are constantly working to reduce the incidence of HAIs, it is a daunting task.  We live in a  germy world, and the opportunities to spread bacteria in a healthcare setting are abundant.

 

Studies have shown that while compliance rates are improving, up to 50% of health care workers in the United States may fail to consistently wash their hands between patients (cite).

 

This year, the World Health Organization designated May 5th as global  CLEAN YOUR HANDS DAY - to encourage HCWs (Healthcare workers) to improve and sustain hand hygiene practices around the world (see A Movement With Five Moments).

 

 

One of the ongoing concerns regarding nosocomial transmission of pathogens has been that lab coats, neckties, and long sleeves might help to spread harmful bacteria from patient to patient in a healthcare facility.

 

In response, in 2007 the NHS banned the wearing of long-sleeved white coats, wristwatches, and neckties by HCWs in hospital wards, and in 2009 the AMA (American Medical Assoc.) considered a “bare below the elbows” dress code during their annual meeting, but decided the issue needed more study (see Lab Coat Legislation).

 

The rap against lab coats and neckties has primarily been that they are not usually freshly laundered every day.

 

One recent study showed that 62% of doctors surveyed waited 2-weeks or longer to launder their coats. 

 

 

While that sounds like a bit of a red flag, earlier this year we saw a study (see The Long And The Short Of It) that found no statistical difference between the amount of bacteria of freshly laundered short sleeve uniforms versus infrequently laundered white coats after only 8 hours wear.

 

And what isn’t known is how well pathogens transfer from contaminated uniforms to the surrounding environment, or on to patients.

 

Today, another study appears in APIC’s American Journal of Infection Control, that looks at the prevalence of harmful bacteria on uniforms worn in a university-affiliated hospital in Israel.

 

The areas of each uniform tested were the abdominal zone, sleeves' ends and pockets.

 

Potentially pathogenic bacteria were isolated from the uniforms of 85 participants (63%) and were detected in half the samples taken.

 

They found 21 cultures from the nurses uniforms and 6 from physician uniforms grew multi-drug resistant pathogens, including 8 that grew MRSA.

 

While a bit disconcerting, given the environment in which these uniforms are worn, and previous studies we’ve seen, these results are not all that surprising.

 

The abstract can be read at:

 

AJIC: American Journal of Infection Control
Volume 39, Issue 7 , Pages 555-559, September 2011

Nursing and physician attire as possible source of nosocomial infections

Conclusion

Up to 60% of hospital staff’s uniforms are colonized with potentially pathogenic bacteria, including drug-resistant organisms. It remains to be determined whether these bacteria can be transferred to patients and cause clinically relevant infection.

In an Elsevier Health Services Press Release (Doctors' and nurses' hospital uniforms contain dangerous bacteria majority of the time, study shows), APIC President Russell Olmsted, MPH, CIC is quoted as saying:

 

"It is important to put these study results into perspective. Any clothing that is worn by humans will become contaminated with microorganisms. The cornerstone of infection prevention remains the use of hand hygiene to prevent the movement of microbes from these surfaces to patients.

 

New evidence such as this study by Dr. Wiener-Well is helpful to improve the understanding of potential sources of contamination but, as is true for many studies, it raises additional questions that need to be investigated."

 

 

Last year, according to Infection Control Today, the American Medical Association (AMA)  announced plans to begin formal research on "textile transmission of infections" singling out the "physician's white lab coat as a primary concern associated with textile transmission of infections."

 

Promising new technologies, including bacteria-resistant fabrics, are being developed in hopes that they will reduce HAIs.

 

But for now, more research is needed to determine just how much of a role contaminated uniforms really play in the spread of harmful pathogens to patients in the hospital.

»» Read More

Fomite to Fingers To Face: A Triple Play Combination

 

 

 

 Photo Credit – CDC 

# 5741

 

Fomites are any surface or object that can become contaminated with viral or bacterial pathogens and that can act as a vehicle of transmission. 

 

Surfaces like the touch screen on your bank’s ATM, the door knob to a public restroom, or the the handle of a shopping cart are touched by scores of people every day.  

 

And some of those people, undoubtedly, are leaving behind bacteria and viruses you really don’t want to get.

 

Last June (see Firefighters & MRSA Revisited) I wrote of a study by researchers from the University of Washington that looked for – and found – MRSA (Methicillin-resistant Staphylococcus aureus) contaminated surfaces at fire houses in Snohomish county.

 

MRSA was detected in 4% of samples taken from places such as kitchens, bathrooms, and rescue vehicles – and researchers also found 30% of firefighters who volunteered to be tested were colonized with either MRSA or S. aureus in their noses.

 

While fomites have long been suspected of playing a significant role in the transmission of diseases, it has only been in recent years that we’ve learned how remarkably resilient many of these pathogens are once they are deposited on an inanimate surface.

 

The 2007 study Significance of Fomites in the Spread of Respiratory and Enteric Viral Disease by Stephanie A. Boone,& Charles P. Gerba found that most viruses survived longer on nonporous surfaces (metal or plastic), and that respiratory viruses (RSV, HPIV, influenza virus, coronavirus, and rhinovirus) could remain viable for hours or even days.

 

Under the right conditions, enteric viruses - like Rotavirus, Norovirus, and Hepatitis A - have been known to survive on fomites from weeks to months

 

It’s a germy world out there, and most people touch their face 10 to 20 times each hour, providing ample opportunities for pathogens to move from fomite to fingers to face.

 

All of which serves as prelude to a study that appears in the August issue of the American Journal of Infection Control that surveyed the hand hygiene knowledge and beliefs of 71 nurses, infection preventionists and hospital environmental services managers.

 

Individual differences in judgments of hand hygiene risk by health care workers

Anne Collins McLaughlin, PhD Fran Walsh, PhD

 

Participants were asked to assess their perceived risk of contracting or spreading an infection in 16 real-life situations. 

 

The authors found that across all levels, healthcare workers perceived surfaces as safer to touch than a patient’s skin, despite studies that have implicated fomites in the chain of disease transmission. 

 

The authors comment:

"Despite the dangers that fomites present, this knowledge may not be common enough among HCWs for them to understand the level of risk when touching surfaces and then touching patients."

 

Studies have shown that although compliance rates are improving, 50% of health care workers in the United States fail to consistently wash their hands between patients (cite).

 

Hospital acquired infections (HAIs) remain a huge problem, and exact a terrible toll on patients and their families.

 

This from the HHS.

 

HHS Action Plan to Prevent Healthcare-Associated Infections: Introduction

Healthcare-associated infections exact a significant toll on human life. They are among the top ten leading causes of death in the United States, accounting for an estimated 1.7 million infections and 99,000 associated deaths in 2002.

 

Of course, this isn’t just a problem in the United States, but also around the world. 

 

So this year the World Health Organization designated May 5th as global  CLEAN YOUR HANDS DAY - to encourage HCWs (Healthcare workers) to improve and sustain hand hygiene practices around the world (see A Movement With Five Moments).

 

 

 

For some earlier blogs on the importance of fomites in the transmission of disease, and the value of hand hygiene you may wish to revisit:

 

CMAJ: Infectious Risks In Family Doctor’s Offices

Hand Hygiene Among Doctors Exposed

MDs Behaving Badly

Suitable For Framing

 

And lastly . . . to start your week off with a smile, a return engagement by that consummate entertainer, one that Maryn McKenna  introduced me to a couple of years ago . . .  the one you all know and  love . . give it up for GERMY, in the award winning all singing, all dancing production of Soapacabana!

Stick around for the outtakes!

»» Read More