An outbreak of mupirocin-resistant Staphylococcus aureus on a dermatology ward associated with an environmental reservoir

Handwashing basins and healthcare associated infections: Bacterial diversity in biofilms on faucets and drains

BACKGROUND

Increasingly, hospital handwashing basins have been identified as a source of healthcare-associated infections. Biofilms formed on the faucet and drains of handbasins can potentially harbour pathogenic microbes and promote the dissemination of antimicrobial resistance. However, little is known about the diversity of these biofilm communities and the routes of contamination.

AIM

The aim of this paper was to use 16S rRNA gene amplicon sequencing to investigate the diversity of prokaryote communities present in faucet and drain biofilm samples taken from hospital and residential handbasins.

FINDINGS

The biofilm prokaryotes communities were diverse, with high abundances of potentially corrosive, biofilm forming and pathogenic genera, including those that are not typically waterborne. The β-diversity showed statistically significant differences in the variation of bacterial communities on the basis on building type (hospital vs residential p = 0.0415). However, there was no statistically significant clustering based on sampling site (faucet vs drain p = 0.46). When examining the β-diversity between individual factors, there was a significant difference between drain biofilms of different buildings (hospital drain vs residential drain p = 0.0338).

CONCLUSION

This study demonstrated that biofilms from hospital and residential handbasins contain complex and diverse microbial communities that differ significantly by building type. It also showed biofilms formed on the faucet and drain of a hospital's handbasins were not significantly different. Future research is needed to understand the potential mechanisms of transfer between drains and faucets of hospital handbasins. This information will inform improved infection control guidelines to control this underrecognized source of infections.

Hospital cleaning: past, present, and future

INTRODUCTION

The importance of hospital cleaning for controlling healthcare-associated infection (HAI) has taken years to acknowledge. This is mainly because the removal of dirt is inextricably entwined with gender and social status, along with lack of evidence and confusion over HAI definitions. Reducing so-called endogenous infection due to human carriage entails patient screening, decolonisation and/or prophylaxis, whereas adequate ventilation, plumbing and cleaning are needed to reduce exogenous infection. These infection types remain difficult to separate and quantitate. Patients themselves demonstrate wide-ranging vulnerability to infection, which further complicates attempted ranking of control interventions, including cleaning. There has been disproportionate attention towards endogenous infection with less interest in managing environmental reservoirs.

QUANTIFYING CLEANING AND CLEANLINESS

Finding evidence for cleaning is compromised by the fact that modelling HAI rates against arbitrary measurements of cleaning/cleanliness requires universal standards and these are not yet established. Furthermore, the distinction between cleaning (soil removal) and cleanliness (soil remaining) is usually overlooked. Tangible bench marking for both cleaning methods and all surface types within different units, with modification according to patient status, would be invaluable for domestic planning, monitoring and specification.

AIMS AND OBJECTIVES

This narrative review will focus on recent history and current status of cleaning in hospitals. While its importance is now generally accepted, cleaning practices still need attention in order to determine how, when and where to clean. Renewed interest in removal and monitoring of surface bioburden would help to embed risk-based practice in hospitals across the world.

Water as a Source of Antimicrobial Resistance and Healthcare-Associated Infections

Healthcare-associated infections (HAIs) are one of the most common patient complications, affecting 7% of patients in developed countries each year. The rise of antimicrobial resistant (AMR) bacteria has been identified as one of the biggest global health challenges, resulting in an estimated 23,000 deaths in the US annually. Environmental reservoirs for AMR bacteria such as bed rails, light switches and doorknobs have been identified in the past and addressed with infection prevention guidelines. However, water and water-related devices are often overlooked as potential sources of HAI outbreaks. This systematic review examines the role of water and water-related devices in the transmission of AMR bacteria responsible for HAIs, discussing common waterborne devices, pathogens, and surveillance strategies. AMR strains of previously described waterborne pathogens including Pseudomonas aeruginosa, Mycobacterium spp., and Legionella spp. were commonly isolated. However, methicillin-resistant Staphylococcus aureus and carbapenem-resistant Enterobacteriaceae that are not typically associated with water were also isolated. Biofilms were identified as a hot spot for the dissemination of genes responsible for survival functions. A limitation identified was a lack of consistency between environmental screening scope, isolation methodology, and antimicrobial resistance characterization. Broad universal environmental surveillance guidelines must be developed and adopted to monitor AMR pathogens, allowing prediction of future threats before waterborne infection outbreaks occur.

Efficacy of an Ethanol-Based Hand Sanitizer for the Disinfection of Blood Pressure Cuffs

Blood pressure cuffs (BP cuffs) have been implicated in some nosocomial outbreaks. We compared the efficacy of an ethanol-based hand sanitizer (EBHS) with a detergent/disinfectant for the disinfection of BP cuffs. The inner sides of 30 BP cuffs were sampled for bacterial culture. Then, the same area was divided into halves. One half was disinfected by a detergent/disinfectant and the other was disinfected by an EBHS. The bacterial count decreased significantly with both disinfectants (p < 0.0001 compared with before disinfection). The bacterial count decrease seemed greater with the EBHS compared with the detergent/disinfectant, but the difference was not significant. Therefore, within the limits of a single application, the EBHS was an efficacious means of BP cuff disinfection. However, the repeated exposure to emollients contained in EBHS may require further studies before validating these results.

High-touch surfaces: microbial neighbours at hand

Despite considerable efforts, healthcare-associated infections (HAIs) continue to be globally responsible for serious morbidity, increased costs and prolonged length of stay. Among potentially preventable sources of microbial pathogens causing HAIs, patient care items and environmental surfaces frequently touched play an important role in the chain of transmission. Microorganisms contaminating such high-touch surfaces include Gram-positive and Gram-negative bacteria, viruses, yeasts and parasites, with improved cleaning and disinfection effectively decreasing the rate of HAIs. Manual and automated surface cleaning strategies used in the control of infectious outbreaks are discussed and current trends concerning the prevention of contamination by the use of antimicrobial surfaces are taken into consideration in this manuscript.

Controlling hospital-acquired infection: focus on the role of the environment and new technologies for decontamination

There is increasing interest in the role of cleaning for managing hospital-acquired infections (HAI). Pathogens such as vancomycin-resistant enterococci (VRE), methicillin-resistant Staphylococcus aureus (MRSA), multiresistant Gram-negative bacilli, norovirus, and Clostridium difficile persist in the health care environment for days. Both detergent- and disinfectant-based cleaning can help control these pathogens, although difficulties with measuring cleanliness have compromised the quality of published evidence. Traditional cleaning methods are notoriously inefficient for decontamination, and new approaches have been proposed, including disinfectants, steam, automated dispersal systems, and antimicrobial surfaces. These methods are difficult to evaluate for cost-effectiveness because environmental data are not usually modeled against patient outcome. Recent studies have reported the value of physically removing soil using detergent, compared with more expensive (and toxic) disinfectants. Simple cleaning methods should be evaluated against nonmanual disinfection using standardized sampling and surveillance. Given worldwide concern over escalating antimicrobial resistance, it is clear that more studies on health care decontamination are required. Cleaning schedules should be adapted to reflect clinical risk, location, type of site, and hand touch frequency and should be evaluated for cost versus benefit for both routine and outbreak situations. Forthcoming evidence on the role of antimicrobial surfaces could supplement infection prevention strategies for health care environments, including those targeting multidrug-resistant pathogens.

Preventing surgical site infections: a randomized, open-label trial of nasal mupirocin ointment and nasal povidone-iodine solution

BACKGROUND

Treatment of Staphylococcus aureus colonization before surgery reduces risk of surgical site infection (SSI). The regimen of nasal mupirocin ointment and topical chlorhexidine gluconate is effective, but cost and patient compliance may be a barrier. Nasal povidone-iodine solution may provide an alternative to mupirocin.

METHODS

We conducted an investigator-initiated, open-label, randomized trial comparing SSI after arthroplasty or spine fusion in patients receiving topical chlorhexidine wipes in combination with either twice daily application of nasal mupirocin ointment during the 5 days before surgery or 2 applications of povidone-iodine solution into each nostril within 2 hours of surgical incision. The primary study end point was deep SSI within the 3 months after surgery.

RESULTS

In the modified intent-to-treat analysis, a deep SSI developed after 14 of 855 surgical procedures in the mupirocin group and 6 of 842 surgical procedures in the povidone-iodine group (P = .1); S. aureus deep SSI developed after 5 surgical procedures in the mupirocin group and 1 surgical procedure in the povidone-iodine group (P = .2). In the per protocol analysis, S. aureus deep SSI developed in 5 of 763 surgical procedures in the mupirocin group and 0 of 776 surgical procedures in the povidone-iodine group (P = .03).

CONCLUSIONS

Nasal povidone-iodine may be considered as an alternative to mupirocin in a multifaceted approach to reduce SSI.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT01313182.

Screening and characterization of Staphylococcus aureus from ophthalmology clinic surfaces: a proposed surveillance tool

PURPOSE

To screen environmental surfaces of an outpatient ophthalmic clinic for methicillin-susceptible and methicillin-resistant Staphylococcus aureus (MSSA and MRSA); to identify the most commonly contaminated surfaces and to phenotype and genotype all collected isolates.

DESIGN

A single institution, 1-year prospective environmental study.

METHODS

Commonly touched surfaces in examination rooms and common areas were targeted and sampled on a quarterly basis for 1 year. Samples were collected using electrostatic cloths and swabs. S. aureus was isolated using nonselective and selective media. Morphologic characteristics and standard biologic testing were used to confirm staphylococcal species. S. aureus isolates were phenotypically (Kirby-Bauer method) and genotypically characterized (mecA confirmation, SCCmec typing and pulsed-field gel electrophoresis). Dendrogram analysis was used to establish genetic relatedness between the isolates.

RESULTS

Of 112 total samples, 27 (24%) and 5 (4%) were MSSA- and MRSA-positive, respectively. Both community-associated (SCCmec IV, USA300) and hospital-associated (SCCmec II, USA100) MRSA isolates were found. No single surface remained consistently positive with the same isolate over time, and molecular analysis demonstrated high levels of diversity among isolates. Doorknobs, slit-lamp headrests and chinrests, and computer keyboards were commonly found to be contaminated.

CONCLUSIONS

The proposed surveillance protocol successfully allowed the detection of both MSSA and MRSA contaminating important high-touch surfaces in a representative ophthalmology clinic. Frequently contaminated surfaces must be targeted for routine cleaning and disinfection because there is a constant introduction of clones over time. Hence, other clinics may consider implementing and adapting surveillance tools, like the one described here, to help them control these important nosocomial pathogens.

Spatial and temporal analyses to investigate infectious disease transmission within healthcare settings

Background

Healthcare-associated infections (HCAIs) cause significant morbidity and mortality worldwide, and outbreaks are often only identified after they reach high levels. A wide range of data is collected within healthcare settings; however, the extent to which this information is used to understand HCAI dynamics has not been quantified.

Aim

To examine the use of spatiotemporal analyses to identify and prevent HCAI transmission in healthcare settings, and to provide recommendations for expanding the use of these techniques.

Methods

A systematic review of the literature was undertaken, focusing on spatiotemporal examination of infectious diseases in healthcare settings. Abstracts and full-text articles were reviewed independently by two authors to determine inclusion.

Findings

In total, 146 studies met the inclusion criteria. There was considerable variation in the use of data, with surprisingly few studies (N = 22) using spatiotemporal-specific analyses to extend knowledge of HCAI transmission dynamics. The remaining 124 studies were descriptive. A modest increase in the application of statistical analyses has occurred in recent years.

Conclusion

The incorporation of spatiotemporal analysis has been limited in healthcare settings, with only 15% of studies including any such analysis. Analytical studies provided greater data on transmission dynamics and effective control interventions than studies without spatiotemporal analyses. This indicates the need for greater integration of spatiotemporal techniques into HCAI investigations, as even simple analyses provide significant improvements in the understanding of prevention over simple descriptive summaries.

Fluorescence characterization of clinically-important bacteria

Healthcare-associated infections (HCAI/HAI) represent a substantial threat to patient health during hospitalization and incur billions of dollars additional cost for subsequent treatment. One promising method for the detection of bacterial contamination in a clinical setting before an HAI outbreak occurs is to exploit native fluorescence of cellular molecules for a hand-held, rapid-sweep surveillance instrument. Previous studies have shown fluorescence-based detection to be sensitive and effective for food-borne and environmental microorganisms, and even to be able to distinguish between cell types, but this powerful technique has not yet been deployed on the macroscale for the primary surveillance of contamination in healthcare facilities to prevent HAI. Here we report experimental data for the specification and design of such a fluorescence-based detection instrument. We have characterized the complete fluorescence response of eleven clinically-relevant bacteria by generating excitation-emission matrices (EEMs) over broad wavelength ranges. Furthermore, a number of surfaces and items of equipment commonly present on a ward, and potentially responsible for pathogen transfer, have been analyzed for potential issues of background fluorescence masking the signal from contaminant bacteria. These include bedside handrails, nurse call button, blood pressure cuff and ward computer keyboard, as well as disinfectant cleaning products and microfiber cloth. All examined bacterial strains exhibited a distinctive double-peak fluorescence feature associated with tryptophan with no other cellular fluorophore detected. Thus, this fluorescence survey found that an emission peak of 340nm, from an excitation source at 280nm, was the cellular fluorescence signal to target for detection of bacterial contamination. The majority of materials analysed offer a spectral window through which bacterial contamination could indeed be detected. A few instances were found of potential problems of background fluorescence masking that of bacteria, but in the case of the microfiber cleaning cloth, imaging techniques could morphologically distinguish between stray strands and bacterial contamination.

Contamination of blood pressure cuffs by methicillin-resistant Staphylococcus aureus and preventive measures

Background

Although blood pressure cuffs are commonly used and shared in medical facilities, their routine disinfection is performed infrequently.

Aims

We investigated the contamination of blood pressure cuffs by methicillin-resistant Staphylococcus aureus (MRSA).

Methods

The MRSA level on the inner side (the surface in contact with patients’ skin) of blood pressure cuffs used in the wards and outpatient clinics of a university hospital (733 beds) was determined using the gauze and swab wiping methods.

Results

Using the gauze wiping method (n = 35), the MRSA contamination rate was 31.4 %, and the MRSA contamination level was 1,702.6 ± 9,996.1 (0–58, 320) colony-forming units (cfu)/cuff. No MRSA was detected on blood pressure cuffs after washing (n = 30) or wiping with 80 vol% ethanol (n = 18).

Conclusions

Blood pressure cuffs are frequently contaminated by MRSA.

Evidence that contaminated surfaces contribute to the transmission of hospital pathogens and an overview of strategies to address contaminated surfaces in hospital settings

Evidence that contaminated surfaces contribute to the transmission of hospital pathogens comes from studies modeling transmission routes, microbiologic studies, observational epidemiologic studies, intervention studies, and outbreak reports. This review presents evidence that contaminated surfaces contribute to transmission and discusses the various strategies currently available to address environmental contamination in hospitals.

Pattern of bacterial colonization in a new neonatal intensive care unit and its association with infections in infants

BACKGROUND

There is paucity of information on the pattern of bacterial colonization of a new neonatal intensive care unit.

OBJECTIVE

To study the pattern of bacterial colonization on the environmental surfaces in a new neonatal intensive care unit (NICU) and correlate it with infections in the infants.

METHODS

Environmental cultures from the faucets and computer keyboards in the NICU were obtained prospectively every 2 weeks for 1 year. Positive blood, cerebrospinal fluid, and respiratory cultures from the infants in the NICU were also obtained.

RESULTS

A total of 175 swab cultures was collected, which were sterile for initial 6-week period. Subsequently, 31 cultures grew microbes: 26 (83.8%) from the faucets and 5 (16.2%) from the computers keyboard (P < .001). Of the 48 positive blood cultures in NICU patients, 6 (12.5%) matched the organism growing from the surveillance sites, but the correlation was not significant (P = .076). None of the 31 positive respiratory cultures and 1 positive cerebrospinal fluid culture correlated to the organisms grown from the NICU environment.

CONCLUSION

The environment was colonized after an initial period of sterile cultures in a new NICU. Once colonized, they can persist, increasing the risk of developing resistance to antibiotics. They did not correlate with the positive cultures from the infants admitted to the NICU during the study period.

Methicillin-resistant Staphylococcus aureus burden in nursing homes associated with environmental contamination of common areas

OBJECTIVES

To determine whether environmental cleaning and contamination are associated with variation in the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) between nursing homes.

DESIGN

Prospective study of environmental contamination and cleaning quality.

SETTING

Nursing home.

PARTICIPANTS

Ten California nursing homes.

MEASUREMENTS

Nursing homes were categorized into two groups based upon high and low differences in MRSA point prevalence and admission prevalence (delta prevalence) from nares screenings of nursing home residents. Environmental cleaning and infection control practices were evaluated by culturing common area objects for MRSA, assessing removal of intentionally applied marks visible only under ultraviolet (UV) light, and administering surveys on infection control and cleaning.

RESULTS

Overall, 16% (78/500) of objects were MRSA positive, and 22% (129/577) of UV-visible marks were removed. A higher proportion of MRSA-positive objects was found in the high (19%) than in low (10%) nursing home groups (P = .005). Infection control and cleaning policies varied, including the frequency of common room cleaning (median 2.5 times daily, range 1-3 times daily) and time spent cleaning per room (median 18 minutes, range 7-45 minutes). In multivariate models, MRSA-positive objects were associated with high delta prevalence nursing homes (odds ratio (OR) = 2.8, P = .005), less time spent cleaning each room (OR = 2.9, P < .001), and less-frequent cleaning of common rooms (OR = 1.5, P = .01).

CONCLUSION

Substantial variation was found in MRSA environmental contamination, infection control practices, and cleaning quality. MRSA environmental contamination was associated with greater differences between MRSA point and admission prevalence, less-frequent common room cleaning, and less time spent cleaning per room, which suggests that modifying cleaning practices may reduce MRSA environmental contamination and burden in nursing homes.

Colonization pressure adjusted by degree of environmental contamination: a better indicator for predicting methicillin-resistant Staphylococcus aureus acquisition

BACKGROUND

Colonization pressure has been confirmed as an important risk factor for methicillin-resistant Staphylococcus aureus (MRSA) acquisition among inpatients, but their precise relationship has not been well investigated. Because MRSA carriers can disperse MRSA into their immediate environment with different abilities, the relationship among colonization pressure, the degree of MRSA contamination in environment surrounding MRSA carriers, and MRSA transmission should be explored to facilitate efficient implementation of infection control measures.

METHODS

Active MRSA screening and environmental sampling were performed in a 23-bed emergency ward (EW) and a 7-bed respiratory intensive care unit (RICU) between March 2009 and February 2010. Weekly colonization pressure (WCP) was modified to WCPe (WCP adjusted by degree of environmental contamination). Receiver operating characteristic curve and correlation analyses were used to analyze the accuracy of WCPe in predicting MRSA acquisition and their correlation, respectively.

RESULTS

We found that 34.1% (858/2,520) of the immediate environmental sites of MRSA-positive patients were contaminated with MRSA. The areas under the receiver operating characteristic curve of WCPe reached as high as 0.784 (95% confidence interval, 0.659-0.909; P < .01) for the EW and 0.866 (95% confidence interval, 0.766-0.967; P < .01) for the RICU. Spearman's correlation coefficient (r) indicated a positive and significant correlation between WCPe and MRSA acquisition rate in the subsequent weeks for both the EW (r = 0.45; P = .001) and RICU (r = 0.51; P < .001).

CONCLUSION

Active MRSA screening combined with targeted environmental contamination monitoring could be a more efficient measure for determining the magnitude of the MRSA reservoir in wards occupied by MRSA carriers. WCPe showed moderate prediction accuracy for both the EW and the RICU, and a threshold WCPe value may be used as a predictor to enhance infection control measures, especially for medical facilities without a sufficient number of single rooms.

A prospective study of the case-notes of MRSA-positive patients: a vehicle of MRSA spread

INTRODUCTION

Methicillin-resistant Staphylococcus aureus (MRSA) has received much publicity and remains a major problem for the health service. The aim of this study was to determine whether case-notes of MRSA-positive patients can act as a vehicle for MRSA transmission.

PATIENTS AND METHODS

A prospective study was performed of patients with active MRSA infection identified from a microbiology department database. Two swabs were taken from the cover of the case-notes and the page with the most recent entry for identification of MRSA using MRSA ID (Chromogenic agar medium), Pastorex and DNase tests. Positive case-notes were re-swabbed 96 h later.

RESULTS

A total of 50 MRSA-positive patients were identified from medical, surgical, high dependency and intensive care wards. Three sets of notes were MRSA positive (3/50; 6%). None of the positive case-notes was positive on re-swabbing at 96 h.

CONCLUSIONS

Case-notes of MRSA-positive patients can act as carriers of MRSA with the potential to spread MRSA to both healthcare and non-healthcare workers without direct contact with infected patients. We recommend extending the universal precautions to the handling of case-notes belonging to MRSA-infected patients.

Two cases of corneal ulcer due to methicillin-resistant Staphylococcus aureus in high risk groups

Considering the popular use of antibiotic-containing eyedrops in Korea, it is important to know the emerging antibiotic-resistant strains of bacteria before treating infectious eye diseases. This is especially important in high-risk groups because of the high incidence of resistant infections and the subsequent treatment requirements. We report two cases of methicillin-resistant Staphylococcus aureus (MRSA) corneal ulcers in high-risk groups. The first case involved a patient who had keratitis after using antibiotic- and steroid-containing eyedrops to treat a corneal opacity that developed after repeated penetrating keratoplasty. The second case involved a patient who used antibiotic-containing eyedrops and a topical lubricant on a regular basis for >1 month to treat exposure keratitis due to lagophthalmos. The second patient's problems, which included a persistent superficial infiltration, developed after brain tumor surgery. Both cases showed MRSA on corneal culture, and the corneal ulcers improved in both patients after the application of vancomycin-containing eyedrops. In conclusion, MRSA infection should be considered in corneal ulcers that have a round shape, mild superficial infiltration, and slow progression, especially in high-risk groups. This report includes descriptions of the characteristic features, antibiotic sensitivities, prevention, and successful treatment with vancomycin-containing eyedrops for MRSA corneal ulcers.

Community-associated methicillin-resistant Staphylococcus aureus: epidemiology and clinical consequences of an emerging epidemic

Staphylococcus aureus is an important cause of skin and soft-tissue infections (SSTIs), endovascular infections, pneumonia, septic arthritis, endocarditis, osteomyelitis, foreign-body infections, and sepsis. Methicillin-resistant S. aureus (MRSA) isolates were once confined largely to hospitals, other health care environments, and patients frequenting these facilities. Since the mid-1990s, however, there has been an explosion in the number of MRSA infections reported in populations lacking risk factors for exposure to the health care system. This increase in the incidence of MRSA infection has been associated with the recognition of new MRSA clones known as community-associated MRSA (CA-MRSA). CA-MRSA strains differ from the older, health care-associated MRSA strains; they infect a different group of patients, they cause different clinical syndromes, they differ in antimicrobial susceptibility patterns, they spread rapidly among healthy people in the community, and they frequently cause infections in health care environments as well. This review details what is known about the epidemiology of CA-MRSA strains and the clinical spectrum of infectious syndromes associated with them that ranges from a commensal state to severe, overwhelming infection. It also addresses the therapy of these infections and strategies for their prevention.

MRSA and the environment: implications for comprehensive control measures

Environmental contamination with methicillin-resistant Staphylococcus aureus (MRSA) is established soon after colonized or infected patients become resident. There are many studies that detail the mechanisms of spread and environmental survival of methicillin-susceptible Staphylococcus aureus (MSSA); this knowledge translates directly into the same findings for MRSA. The potential ubiquity of MRSA in a health-care setting poses challenges for decontamination. Whereas patients and medical staff are important sources for MRSA spread, the environmental burden may contribute significantly in various contexts. Effective control measures must therefore include consideration for MRSA in the environment.

An evaluation of patient area cleaning in 3 hospitals using a novel targeting methodology

BACKGROUND

Although environmental cleaning and disinfecting practices have become a cornerstone of patient care, assessment of actual compliance with such procedures has not been reported. Using a novel methodology, we developed a means to monitor directly such activities.

METHODS

A nontoxic target solution, which intensely fluoresces with a black light, was formulated to be inconspicuous yet readily removed by housekeeping products. Small volumes of material were confidentially applied to 12 target sites in patient rooms in 3 hospitals following terminal cleaning. The targets were reevaluated following terminal cleaning after several patients had occupied the room.

RESULTS

One hundred fifty-seven rooms and 1404 targets were evaluated. In the 3 hospitals studied, only 45%, 42%, and 56% of targets were removed by routine terminal cleaning/disinfecting activities. The frequency with which various individual sites were cleaned varied widely but was similar in all hospitals.

CONCLUSION

The use of a novel target compound to evaluate housekeeping practices confirmed high rates of cleaning of traditional sites but poor cleaning of many sites that have significant potential for harboring and transmitting microbial pathogens. This methodology has the potential for being used to evaluate objectively the cleaning/disinfecting activities in various health care settings.

Community-associated methicillin-resistant Staphylococcus aureus skin infections in a religious community

In September 2004, an outbreak of community-associated methicillin-resistant Staphylococcus aureus (MRSA) skin and soft tissue infections (SSTI) was reported among members of a religious community. We conducted a retrospective cohort study on all 175 community members; performed a nasal carriage survey, and environmental swab testing. We identified 24 MRSA cases (attack rate 14%). In multivariate analysis, sauna use [odds ratio (OR) 19.1, 95% confidence interval (CI) 2.7-206.1] and antimicrobial use within 12 months before infection (OR 11.7, 95% CI 2.9-47.6) were risk factors for infection. MRSA nasal carriage rate was 0.6% (1/174). Nine of 10 clinical isolates and an isolate from an administrative office within the community had the pulsed-field gel electrophoresis type USA300. Targeted hygiene improvement, wound care, and environmental cleaning were implemented. We describe the first reported outbreak of MRSA SSTI in a religious community. Adherence to appropriate personal and environmental hygiene might be critical factors in controlling transmission.

Reduction in MRSA environmental contamination with a portable HEPA-filtration unit

There is renewed interest in the hospital environment as a potentially important factor for cross-infection with methicillin-resistant Staphylococcus aureus (MRSA) and other nosocomial pathogens. The aim of this study was to evaluate the effectiveness of a portable high-efficiency particulate air (HEPA)-filtration unit (IQAir Cleanroom H13, Incen AG, Goldach, Switzerland) at reducing MRSA environmental surface contamination within a clinical setting. The MRSA contamination rate on horizontal surfaces was assessed with agar settle plates in ward side-rooms of three patients who were heavy MRSA dispersers. Contamination rates were measured at different air filtration rates (60-235 m(3)/h) and compared with no air filtration using Poisson regression. Without air filtration, between 80% and 100% of settle plates were positive for MRSA, with the mean number of MRSA colony-forming units (cfu)/10-h exposure/plate ranging from 4.1 to 27.7. Air filtration at a rate of 140 m(3)/h (one patient) and 235 m(3)/h (two patients), resulted in a highly significant decrease in contamination rates compared with no air filtration (adjusted rate ratios 0.037, 0.099 and 0.248, respectively; P < 0.001 for each). A strong association was demonstrated between the rate of air filtration and the mean number of MRSA cfu/10-h exposure/plate (P for trend < 0.001). In conclusion, this portable HEPA-filtration unit can significantly reduce MRSA environmental contamination within patient isolation rooms, and this may prove to be a useful addition to existing MRSA infection control measures.

Improved Cleaning of Patient Rooms Using a New Targeting Method

We developed a new method using an invisible fluorescent marker to target standardized high-touch surfaces in hospital rooms. Evaluation of 1404 surface objects in 157 rooms in 3 hospitals revealed that 47% of targets had been cleaned. Educational interventions were implemented, leading to sustained improvement in cleaning of all objects and a >2-fold improvement in cleaning of surfaces previously cleaned <85% of the time (P<or=.001).

Open endotracheal tubes may be safely left on an ED airway cart for 48 hours

OBJECTIVE

To determine if endotracheal tubes (ETTs) that are opened, prepared, and stored in an ED airway cart are prone to bacterial contamination.

METHODS

A prospective study conducted in the ED of a level 1 trauma center. A study group of 50 endotracheal tubes were opened, preloaded with a stylet, the cuff checked for integrity by air inflation, and then stored in an ED airway cart. The study group was subdivided into 5 groups of 10 ETTs each, cultured at different time intervals. The ETTs were cultured at 6, 12, 24, 36, and 48 hours for the presence of bacterial contamination. The control group consisted of 10 ETTs that were left in their sterile packing in the ED airway cart and then removed at 48 hours and cultured.

RESULTS

In the study group, 7 (14%) ETTs resulted in a positive culture; 43 ETTs cultured negative for bacteria. In the control group, 2 (20%) ETTs cultured positive, the remainder was all negative. There was no statistically significant difference between the 2 groups (P = .63). If only clinically significant bacteria are considered, defined as a culture with 5 or more colony-forming units, 3 ETTs in the study group cultured positive; there were no clinically significant bacteria cultured in the control group. Once again, there was no statistically significant difference between the 2 groups, with a P value of .57.

CONCLUSION

It appears that opening, preparing, and storing ETTs in an ED airway cart for up to 48 hours does not increase the risk of bacterial contamination of the ETTs.

The dermatoscope: a potential source of nosocomial infection?

Dermatoscopes are directly placed on the skin of patients and therefore may harbour potentially pathogenic bacteria. In this study we assessed bacterial contamination of dermatoscopes during routine use and examined the effectiveness of isopropyl alcohol and disposable lens covers. Aerobic bacterial cultures were performed on randomly selected dermatoscopes after examination of 39 patients. In addition, bacterial contamination of dermatoscopes after cleaning with 70% isopropyl alcohol and after using a disposable transparent lens cover was tested. Bacteria such as Staphylococcus epidermidis, Micrococcus species and Corynebacterium species, which are usually present on the skin, were repeatedly identified. In addition, rare bacteria such as Moraxella species were found. Known nosocomial micro-organisms such as Staphylococcus aureus were recovered from hospitalized patients. Disinfection with 70% isopropyl alcohol and the use of a disposable lens cover significantly reduced the number of bacteria. Image quality was identical with and without the use of a transparent lens cover. Dermatoscopes harbour potential pathogens and may be a source of bacterial transmission. Isopropyl alcohol is an effective cleaning agent for dermatoscopes. Disposable lens covers completely prevented bacterial transmission and are therefore recommended for routine dermatoscopy, especially in hospitalized patients.

Computer keyboards and faucet handles as reservoirs of nosocomial pathogens in the intensive care unit

PURPOSE

We postulate that computer keyboards and faucet handles are significant reservoirs of nosocomial pathogens in the intensive care unit (ICU) setting.

METHODS

Sterile swab samples were obtained from 10 keyboards and 8 pairs of faucet handles in the medical ICU at Tripler Army Medical Center during a period of 2 months. Methicillin-resistant Staphylococcus aureus (MRSA) obtained from the environmental and patient specimens were sent for DNA identification by using pulsed-field gel electrophoresis.

RESULTS

A total of 144 samples were obtained (80 keyboards and 64 faucet handles), yielding 33 isolates. The colonization rate for keyboards was 24% for all rooms and 26% in occupied rooms. Rates for faucet handles in all rooms and occupied rooms were 11% and 15%, respectively. The environmental isolates annd their prevalence were: MRS, 49%; Enterococcus, 18%; Enterobacter, 12%; and all other gram-negative rods, 21%. Fourteen individual patient isolates were recorded: MRSA, 43%; Enterobacter, 21%; other gram-negative rods, 36%; and Enterococcus, 0%. By using pulsed-field gel electrophoresis, an indistinguishable strain of MRSA was identified in two patients, the keyboards and faucet handles in their respective rooms, and on other keyboards throughout the ICU, including the doctors' station.

CONCLUSIONS

The colonization rate for keyboards and faucet handles, novel and unrecognized fomites, is greater than that of other well-studied ICU surfaces in rooms with patients positive for MRSA. Our findings suggest an associated pattern of environmental contamination and patient infection, not limited to the patient's room. Pulsed-field gel electrophoresis results have documented an indistinguishable strain of MRSA present as an environmental contaminant on these two fomites and in two patients with clinical infections patients during the same period. We believe these findings add evidence to support the hypothesis that these particular surfaces may serve as reservoirs of nosocomial pathogens and vectors for cross-transmission in the ICU setting. New infection control policies and engineering plans were initiated on the basis of our results.

An audit of the use of manual handling equipment and their microbiological flora--implications for infection control

A review of the use of manual handling aids in two hospitals found equipment was employed on a multi-patient basis with inadequate cleaning. Sampling with a Casella slit sampler demonstrated frequent contamination by methicillin-resistant Staphylococcus aureus and Clostridium difficile of fabric aids. Recommendations for care of equipment are made.

Keeping MRSA out of a district general hospital

This study describes a three-year audit of methicillin-resistant Staphylococcus aureus (NIRSA) in a district general hospital and surrounding community. Despite a continuing increase in new cases of MRSA both nationally and locally, and the transfer of patients with MRSA from outside, the hospital remains free from endemic MRSA, albeit with occasional sporadic cases. This is attributed to the presence of a Control of Infection team who have introduced and implemented various policies to control MRSA. These include prompt screening of hospital transfers, an effective topical regimen, attention to environmental cleaning, treatment for established infection, tailored protocol for colonized urinary catheters and an educational programme for staff. Some of these policies have been extended into the community. This report also presents data from 172 cases of MRSA, including carriage rate, infection site, antibiogram, phage-typing, treatment and/or clearance outcome and preliminary evaluation of pathogenicity. A questionnaire has been formulated to assess colonization vs infection. Future strategies will be required if the status quo is to be maintained.

Detection of ileS-2 gene encoding mupirocin resistance in methicillin-resistant Staphylococcus aureus by multiplex PCR

The presence of the ileS-2 gene, responsible for mupirocin resistance, in clinical isolates of methicillin-resistant Staphylococcus aureus was determined by multiplex polymerase chain reaction. Three pairs of primers were used, which yielded specific fragments of femA (encoding a unique feature of S. aureus), mecA (encoding resistance to methicillin) and ileS-2 genes. The multiplex polymerase chain reaction system is an easy and time-saving technique that, together with a rapid method for DNA extraction by boiling, may be incorporated as a routine analysis in clinical diagnostic laboratories.

The nose: an underestimated source of Staphylococcus aureus causing wound infection

For the last fifty years, the nose has been intermittently recognized and targeted as a source of Staphylococcus aureus causing surgical site infection. In London in 1959, Williams and co-workers established for the first time that nasal carriers had increased rates of surgical sepsis compared with non-carriers. For half of these patients, the source was the patient's own nose. Post-admission acquisition of tetracycline-resistant strains was associated with even higher rates of infection. The increasing appearance of epidemic methicillin-resistant S. aureus (MRSA) in the 1980s rekindled interest in these (largely overlooked) studies, when the elimination of nasal carriage by topical mupirocin proved pivotal for the control of MRSA in Northern Europe and elsewhere. In the late 1980s and 1990s, Boelaert, Holton and others, appreciating the work performed forty years previously, used nasal mupirocin for the successful prevention of sepsis with S. aureus in patients on haemodialysis and continuous ambulatory peritoneal dialysis without incurring problems with mupirocin resistance. In 1995, Kluytmans and colleagues demonstrated that nasal carriage of S. aureus is a significant risk factor for wound infection after cardiac surgery. Towards the year 2000, the use of prophylactic nasal mupirocin for the prevention of serious sepsis in major clean surgery is emerging as a plausible and exciting new strategy.

Control of an outbreak of an epidemic methicillin-resistant Staphylococcus aureus also resistant to mupirocin

An epidemic methicillin-resistant Staphlococcus aureus (EMRSA-3) appeared in a District hospital in June 1989 as part of a regional outbreak. The dynamics of the outbreak were complex and involved patient transfer between hospitals and wards. Control measures followed UK guidelines and included the use of nasal mupirocin. During these efforts a mupirocin-resistant MRSA [MuMRSA: mupirocin minimum inhibitor concentration (MIC) > 256 mg/L] emerged, probably in a patient who had been given eight mupirocin courses over nine months. The MuMRSA had a narrower phage-typing pattern than EMRSA-3, but was indistinguishable by pulsed-field gel electrophoresis of SmaI chromosomal restriction enzyme digests and its susceptibility pattern to other antibiotics. The results of in vitro curing and gene probing indicated that mupirocin resistance was encoded on a 48 Md plasmid. MuMRSA spread occurred in 12 patients and 11 staff. The affected patients were nursed on the same ward. The strain was eradicated from patients with oral ciprofloxacin and rifampicin, triclosan skin treatment and nasal fusidic acid and bacitracin cream. The control of the outbreak had significant medical, social and financial implications. Fortunately, there were alternative topical agents to mupirocin, an agent which has played such a key role in MRSA eradication in recent years.

Investigation of nosocomial infection caused by arbekacin-resistant, methicillin-resistant Staphylococcus aureus

An outbreak of coagulase VII-producing, arbekacin (ABK)-resistant, methicillin-resistant Staphylococcus aureus (MRSA) occurred between September 1994 and December 1995, involving five different wards. Twenty-one patients developed skin, wound, drainage, or respiratory tract colonization with coagulase VII-producing, (ABK)-resistant MRSA. Phenotypic characteristics (production of enterotoxin and TSST-1, antimicrobial susceptibility) and molecular-typing procedure (plasmid DNA profile, pulsed-field gel electrophoresis [PFGE] and arbitrarily primed polymerase chain reaction [AP-PCR] of chromosomal DNA) in isolated strains were compared. Plasmid analysis identified four different profiles and 19 of 22 strains recovered had identical patterns. PFGE of chromosomal DNA identified three different subtypes and 18 (81.8%) isolates shared the same subtype. AP-PCR also demonstrated that most strains had the same phenotypic characteristics. Although traditional epidemiological methods; for example, coagulase typing, plays a central role in hospital infection control, combination of plasmid DNA profile, AP-PCR, and PFGE may prove to be a particularly informative means of tracking the nosocomial spread of MRSA.

Identification of chromosomal location of mupA gene, encoding low-level mupirocin resistance in staphylococcal isolates

Low- and high-level mupirocin resistance have been reported in Staphylococcus aureus. The expression of plasmid-encoded mupA is responsible for high-level mupirocin resistance. Low-level mupirocin-resistant strains do not contain plasmid-encoded mupA, and a chromosomal location for this gene has not previously been reported. We examined high- and low-level mupirocin-resistant S. aureus strains to determine if mupA was present on the chromosome of low-level-resistant isolates. Southern blot analysis of DNA from four mupirocin-resistant strains identified mupA in both high- and low-level mupirocin-resistant strains. Low-level mupirocin-resistant strains contained a copy of mupA on the chromosome, while the high-level mupirocin-resistant isolate contained a copy of the gene on the plasmid. PCR amplification of genomic DNA from each mupirocin-resistant strain resulted in a 1.65-kb fragment, the predicted product from the intragenic mupA primers. This is the first report of a chromosomal location for the mupA gene conferring low-level mupirocin resistance.

Eradication of the long-term carriage of methicillin-resistant Staphylococcus aureus in patients wearing dentures: a follow-up of 10 patients

To cure the long-term carriage of methicillin-resistant Staphylococcus aureus (MRSA), eradication treatment was given to 10 patients wearing complete dentures. In addition to multiple body sites, MRSA was cultured from the dentures of six patients. The contaminated dentures were rebased and sterilized with heat in order to prevent recolonization. The patients did not use their dentures during the decolonization therapy. Subsequently, MRSA was eradicated from three of these patients but three others remained MRSA-positive despite at least two courses of combined systemic and topical eradication treatment. These particular patients had persistent stomatitis and their dentures were a poor fit, in poor condition and repeatedly grew MRSA. Eradication treatment was successful in the remaining four patients whose dentures were MRSA-negative. These results confirm that dentures may function as foreign bodies and sustain persistent nasopharyngeal. MRSA colonization. Therefore, we suggest that whenever eradication of MRSA is deemed necessary in cases of nasal, oral or pharyngeal carriage, heat treatment of the dentures should be included. Further comparative studies with larger patient populations are needed to evaluate the contribution of dentures to the long-term carriage of MRSA, as well as to assess the value of denture sterilization during the eradication course.

Survival of methicillin-resistant Staphylococcus aureus (MRSA) on naturally contaminated dry mops

The floors of single rooms being used by inpatients colonized by methicillin-resistant Staphylococcus aureus (MRSA) were cleaned using disposable dust-attracting dry mops. Each mop was divided into 12 sections and MRSA quantified serially. This experiment was repeated a total of 21 times for four patients. The MRSA survival rate on the dry mops compared with a control was 59.0-125% after seven days, 26.3-41.6% after 14 days, 0.1-16.2% after 28 days, 0-0.1% after 56 days and 0% after 84 days. MRSA disseminated by patients over the environment can survive for several weeks on dry mops.

Stethoscopes: a potential vector of infection?

STUDY OBJECTIVES

To survey emergency care providers about their stethoscope-cleaning measures and to determine the correlation between these measures and the extent of Staphylococcus carriage.

DESIGN

Prospective cross-sectional analysis.

SETTING

University-affiliated community hospital ED.

PARTICIPANTS

One hundred fifty health care providers, comprising emergency medicine house staff and attending physicians (n = 50), ED nurses (n = 50), and prehospital personnel working in Kent County, Michigan (n = 50).

INTERVENTIONS

Providers were asked how often they cleaned their stethoscopes and which cleaning agents were used. We then cultured each stethoscope by pressing the diaphragm on mannitol agar and incubating the culture aerobically for 48 hours. Staphylococcus aureus was identified by means of standard measures. We examined the effects of different cleaning agents on 24 stethoscopes. The numbers of colony-forming units (CFUs) before and after cleaning with alcohol, nonionic detergent, and antiseptic soap were noted.

RESULTS

Overall, 48% of health care providers (74 of 150) cleaned their stethoscopes daily or weekly, 37% monthly, and 7% yearly; and 7% had never cleaned their stethoscopes. No significant differences were found in the hygiene routines of the three groups of providers surveyed. Use of an alcohol swab was the preferred method of cleaning. One hundred thirty-three stethoscopes (89%) grew staphylococci; 25 (19%) yielded S aureus. Mean staphylococcal bacterial counts ( +/- SD) were 52 +/- 78 CFUs per stethoscope among physicians, 46 +/- 92 CFUs among emergency medical service personnel, and 13 +/- 21 CFUs from the nursing staff (ANOVA, P = .01). Cleaning the stethoscope diaphragm resulted in immediate reduction in the bacterial count: by 94% with alcohol swabs, 90% with nonionic detergent, and 75% with antiseptic soap.

CONCLUSION

Our results confirm that stethoscopes used in emergency practice are often contaminated with staphylococci and are therefore a potential vector of infection. This contamination is greatly reduced by frequent cleaning with alcohol or nonionic detergent.

The significance of nasal carriage of Staphylococcus aureus and the incidence of postoperative wound infection

Staphylococcus aureus infections are associated with considerable morbidity and, in certain situations, mortality. The association between the nasal carriage of S. aureus and subsequent infection has been comprehensively established in a variety of clinical settings, in particular, patients undergoing haemodialysis and continuous ambulatory peritoneal dialysis (CAPD), and in patients undergoing surgery. Postoperative wound infections are associated with a high degree of morbidity and represent an important medical issue. Until recently, eradication of S. aureus nasal carriage by various topical and systemic agents had proved unsuccessful. Mupirocin is a novel topical antibiotic with excellent antibacterial activity against staphylococci. Recent studies have demonstrated that intranasal administration of mupirocin is effective in eradicating the nasal carriage of S. aureus and in reducing the incidence of S. aureus infections in haemodialysis and CAPD patients. It has been suggested that sufficient evidence now exists to test the hypothesis that eradication of the carrier state in surgical patients preoperatively may reduce the incidence of S. aureus postoperative wound infections.

Characterization of a conjugative staphylococcal mupirocin resistance plasmid

We studied conjugative plasmids encoding high-level mupirocin resistance. These plasmids were found in Staphylococcus aureus isolates from two geographic locations in the United States. Transfer genes on three mupirocin resistance plasmids with different restriction endonuclease profiles were indistinguishable by DNA hybridization from those on pG01, a conjugative aminoglycoside resistance plasmid representative of similar plasmids that are prevalent in the United States. One mupirocin resistance plasmid, pG0400 (34 kb), was smaller than pG01 (52 kb) because of the absence from pG0400 of DNA, found on pG01, that contained genes encoding resistance to aminoglycosides, trimethoprim, and quaternary ammonium compounds flanked by directly repeated copies of the insertion sequence (IS)-like element IS431-IS257. The plasmids pG0400 and pG01 were otherwise indistinguishable except for the presence in pG0400 of a 4.5-kb HinDIII fragment encoding mupirocin resistance. The added mupirocin resistance gene was flanked by two directly repeated copies of IS431/257. The nucleotide sequence of DNA contiguous to the outside of the IS elements, as well as those of the elements themselves, was identical in both pG01 and pG0400, and there were no target site duplications flanking either copy of the element. We conclude that the mupirocin resistance gene was added to an existing conjugative plasmid in conjunction with the deletion of other resistance genes by recombination at IS elements. The construction of conjugative plasmids carrying a mupirocin resistance gene may be a model for the mobility of other resistance genes newly acquired by staphylococci.