Prospective study of infection, colonization and carriage of methicillin-resistant Staphylococcus aureus in an outbreak affecting 990 patients

The added value of perineal swabs when screening for asymptomatic methicillin-resistant Staphylococcus aureus colonization and risk factors for perineal carriage

We examined the added value of perineal swabs in addition to nose and throat swabs when screening for Methicillin-resistant Staphylococcus aureus colonization, and risk factors for perineal carriage in 6,642 patients. In our mainly primary care setting, the added value was 9.3%. Patients <3 or ≥80 had the highest risk.

Optimal Design of Paired Built Environment Interventions for Control of MDROs in Acute Care and Community Hospitals

OBJECTIVES

Our goal was to optimize infection control of paired environmental control interventions within hospitals to reduce methicillin-resistant Staphylococcus aureus (MRSA), carbapenem-resistant Enterobacteriaceae (CRE), and vancomycin-resistant Enterococci (VRE).

BACKGROUND

The most widely used infection control interventions are deployment of handwashing (HW) stations, control of relative humidity (RH), and negative pressure (NP) treatment rooms. Direct costs of multidrug-resistant organism (MDRO) infections are typically not included in the design of such interventions.

METHODS

We examined the effectiveness of pairing HW with RH and HW with NP. We used the following three data sets: A meta-analysis of progression rates from uncolonized to colonized to infected, 6 years of MDRO treatment costs from 400 hospitals, and 8 years of MDRO incidence rates at nine army hospitals. We used these data as inputs into an Infection De-Escalation Model with varying budgets to obtain optimal intervention designs. We then computed the infection and prevention rates and cost savings resulting from these designs.

RESULTS

The average direct cost of an MDRO infection was $3,289, $1,535, and $1,067 for MRSA, CRE, and VRE. The mean annual incidence rates per facility were 0.39%, 0.034%, and 0.011% for MRSA, CRE, and VRE. After applying the cost-minimizing intervention pair to each scenario, the percentage reductions in infections (and annual direct cost savings) in large, community, and small acute care hospitals were 69% ($1.5 million), 73% ($631K), 60% ($118K) for MRSA, 52% ($460.5K), 58% ($203K), 50% ($37K) for CRE, and 0%, 0%, and 50% ($12.8K) for VRE.

CONCLUSION

The application of this Infection De-Escalation Model can guide cost-effective decision making in hospital built environment design to improve control of MDRO infections.

Health Disparities in Staphylococcus aureus Transmission and Carriage in a Border Region of the United States Based on Cultural Differences in Social Relationships: Protocol for a Survey Study

Background

Health care–associated Staphylococcus aureus infections are declining but remain common. Conversely, rates of community-associated infections have not decreased because of the inadequacy of public health mechanisms to control transmission in a community setting. Our long-term goal is to use risk-based information from empirical socio-cultural-biological evidence of carriage and transmission to inform intervention strategies that reduce S aureus transmission in the community. Broad differences in social interactions because of cultural affiliation, travel, and residency patterns may impact S aureus carriage and transmission, either as risk or as protective factors.

Objective

This study aims to (1) characterize S aureus carriage rates and compare circulating pathogen genotypes with those associated with disease isolated from local clinical specimens across resident groups and across Hispanic and non-Hispanic white ethnic groups and (2) evaluate social network relationships and social determinants of health-based risk factors for their impact on carriage and transmission of S aureus.

Methods

We combine sociocultural survey approaches to population health sampling with S aureus carriage and pathogen genomic analysis to infer transmission patterns. Whole genome sequences of S aureus from community and clinical sampling will be phylogenetically compared to determine if strains that cause disease (clinical samples) are representative of community genotypes. Phylogenetic comparisons of strains collected from participants within social groups can indicate possible transmission within the group. We can therefore combine transmission data with social determinants of health variables (socioeconomic status, health history, etc) and social network variables (both egocentric and relational) to determine the extent to which social relationships are associated with S aureus transmission.

Results

We conducted a first year pilot test and feasibility test of survey and biological data collection and analytic procedures based on the original funded design for this project (#NIH U54MD012388). That design resulted in survey data collection from 336 groups and 1337 individuals. The protocol, described below, is a revision based on data assessment, new findings for statistical power analyses, and refined data monitoring procedures.

Conclusions

This study is designed to evaluate ethnic-specific prevalence of S aureus carriage in a US border community. The study will also examine the extent to which kin and nonkin social relationships are concordant with carriage prevalence in social groups. Genetic analysis of S aureus strains will further distinguish putative transmission pathways across social relationship contexts and inform our understanding of the correspondence of S aureus reservoirs across clinical and community settings. Basic community-engaged nonprobabilistic sampling procedures provide a rigorous framework for completion of this 5-year study of the social and cultural parameters of S aureus carriage and transmission.

Development of a New Application for Comprehensive Viability Analysis Based on Microbiome Analysis by Next-Generation Sequencing: Insights into Staphylococcal Carriage in Human Nasal Cavities

The nasal carriage rate of Staphylococcus aureus in human is 25 to 30%, and S. aureus sporadically causes severe infections. However, the mechanisms underlying staphylococcal carriage remain largely unknown. In the present study, we constructed an rpoB-based microbiome method for staphylococcal species discrimination. Based on a microbiome scheme targeting viable cell DNA using propidium monoazide (PMA) dye (PMA microbiome method), we also developed a new method to allow the comprehensive viability analysis of any bacterial taxon. To clarify the ecological distribution of staphylococci in the nasal microbiota, we applied these methods in 46 nasal specimens from healthy adults. PMA microbiome results showed that Staphylococcaceae and Corynebacteriaceae were the most predominant viable taxa (average relative abundance: 0.435262 and 0.375195, respectively), and Staphylococcus epidermidis exhibited the highest viability in the nasal microbiota. Staphylococcus aureus detection rates from nasal specimens by rpoB-based conventional and PMA microbiome methods were 84.8% (39 of 46) and 69.5% (32 of 46), respectively, which substantially exceeded the values obtained by a culture method using identical specimens (36.9%). Our results suggest that Staphylococcaceae species, especially S. epidermidis, adapted most successfully to human nasal cavity. High detection of S. aureus DNA by microbiome methods suggests that almost all healthy adults are consistently exposed to S. aureus in everyday life. Furthermore, the large difference in S. aureus detection rates between culture and microbiome methods suggests that S. aureus cells frequently exist in a viable but nonculturable state in nasal cavities. Our method and findings will contribute to a better understanding of the mechanisms underlying carriage of indigenous bacteria.IMPORTANCE Metagenomic analyses, such as 16S rRNA microbiome methods, have provided new insights in various research fields. However, conventional 16S rRNA microbiome methods do not permit taxonomic analysis of only the viable bacteria in a sample and have poor resolving power below the genus level. Our new schemes allowed for viable cell-specific analysis and species discrimination, and nasal microbiome data using these methods provided some interesting findings regarding staphylococcal nasal carriage. According to our comprehensive viability analysis, the high viability of Staphylococcus species, especially Staphylococcus epidermidis, in human nasal carriage suggests that this taxon has adapted most successfully to human nasal tissue. Also, a higher detection rate of S. aureus DNA by microbiome methods (84.8%) than by a culture method (36.9%) suggests that almost all healthy adults are consistently exposed to Staphylococcus aureus in the medium and long term. Our findings will contribute to a better understanding of the mechanisms underlying the carriage of indigenous bacteria.

No apparent transmission of livestock-associated methicillin-resistant Staphylococcus aureus CC398 in a survey of staff at a regional Danish hospital

Background

In recent years, livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) multi locus sequence type CC398 has spread widely in the livestock production in Europe. The rates of LA-MRSA in hospitals have been found to be largely determined by contact to and density of livestock in the area.

Methods

This is a cross sectional study of the prevalence of LA-MRSA among hospital staff in a Danish hospital situated in a livestock production region. We analysed nasal swabs, air and dust samples for the presence of MRSA using PCR and mass spectrometry.

Results

Of 1745 employees, 545 (31%) contributed nasal swabs. MRSA was not detected in any participant, nor was it detected in air or dust at the hospital or in houses of employees living on farms. Four percent of the participants had contact to pigs either directly or through household members. LA-MRSA was detected in two of 26 samples from animal sheds, both of them from pig farms. The participation rate was relatively low, but participants were representative for the source population with regards to animal contact and job titles.

Conclusions

The study suggests a low point prevalence of LA-MRSA carriage in Danish hospital staff even in regions where livestock production is dense. Should more studies confirm our findings we see no need for additional hospital precautions towards LA-MRSA in Denmark at the moment. We think that our data might reduce potential stigmatization of hospital workers with contact to LA-MRSA positive farms at their work places and in their communities.

Electronic supplementary material

The online version of this article (10.1186/s13756-017-0284-y) contains supplementary material, which is available to authorized users.

Evaluation and management of Staphylococcus aureus bacteriuria: an updated review

BACKGROUND AND AIMS

There is little guidance regarding the evaluation and management of patients with Staphylococcus aureus bacteriuria (SABU). Here, we aimed to provide an up-to-date review of the literature.

METHODS

We searched PubMed, Scopus, and clinical trial registries for articles evaluating the epidemiology of SABU, risk factors of SABU, the association of SABU with urinary tract infection, bacteremia and invasive S. aureus infections, and the management of patients with SABU.

RESULTS

S. aureus is an uncommon isolate in urine cultures. It is more common among certain patients, e.g., patients with indwelling urinary tract devices or prior urinary tract instrumentation. SABU may represent asymptomatic bacteriuria, primary urinary tract infection, or hematogenous seeding of the urinary tract associated with other foci of infection. SABU may also serve as the focus for subsequent bacteremia and invasive infections. We did not find any clinical trials regarding the management of patients with SABU.

CONCLUSIONS

Based on our review, we suggest an algorithmic approach for the evaluation and management of patients with SABU. However, evidence from clinical trials is lacking and there are several gaps in the current literature. These are discussed in this review.

Cost Analysis of Universal Screening vs. Risk Factor-Based Screening for Methicillin-Resistant Staphylococcus aureus (MRSA)

Background

The literature remains conflicted regarding the most effective way to screen for MRSA. This study was designed to assess costs associated with universal versus risk factor-based screening for the reduction of nosocomial MRSA transmission.

Methods

The study was conducted at The Ottawa Hospital, a large multi-centre tertiary care facility with approximately 47,000 admissions annually. From January 2006-December 2007, patients underwent risk factor-based screening for MRSA on admission. From January 2008 to August 2009 universal MRSA screening was implemented. A comparison of costs incurred during risk factor-based screening and universal screening was conducted. The model incorporated probabilities relating to the likelihood of being tested and the results of polymerase chain reaction (PCR) testing with associated effects in terms of MRSA bacteremia and true positive and negative test results. Inputted costs included laboratory testing, contact precautions and infection control, private room costs, housekeeping, and length of hospital stay. Deterministic sensitivity analyses were conducted.

Results

The risk factor-based MRSA screening program screened approximately 30% of admitted patients and cost the hospital over $780 000 annually. The universal screening program screened approximately 83% of admitted patients and cost over $1.94 million dollars, representing an excess cost of $1.16 million per year. The estimated additional cost per patient screened was $17.76.

Conclusion

This analysis demonstrated that a universal MRSA screening program was costly from a hospital perspective and was previously known to not be clinically effective at reducing MRSA transmission. These results may be useful to inform future model-based economic analyses of MRSA interventions.

What To Think If the Results of the National Institutes of Health Randomized Trial of Methicillin-ResistantStaphylococcus aureusand Vancomycin-ResistantEnterococcusControl Measures Are Negative (and Other Advice to Young Epidemiologists): A Review and an Au Revoir

The incidence of methicillin-resistantStaphylococcus aureus(MRSA) and vancomycin-resistantEnterococcus(VRE) infections continues to rise in National Nosocomial Infections Surveillance system hospitals, and these pathogens are reportedly causing more than 100,000 infections and many deaths each year in US healthcare facilities. This has led some to insist that control measures are now urgently needed, but several recent articles have suggested that isolation of patients does not work, is not needed, or is unsafe, or that a single cluster-randomized trial could be used to decide such matters. At least 101 studies have reported controlling MRSA infection and 38 have reported controlling VRE infection by means of active detection by surveillance culture and use of isolation for all colonized patients in healthcare settings where the pathogens are epidemic or endemic, in academic and nonacademic hospitals, and in acute care, intensive care, and long-term care settings. MRSA colonization and infection have been controlled to exceedingly low levels in multiple nations and in the state of Western Australia for decades by use of active detection and isolation. Studies suggesting problems with using such data to control MRSA colonization and infection have their own problems, which are discussed. Randomized trials are epidemiologic tools that can sometimes provide erroneous results, and they have not been considered necessary for studying isolation before it is used to control other important infections, such as tuberculosis, smallpox, and severe acute respiratory syndrome. No single epidemiologic study should be considered definitive. One should always weigh all available evidence. Infection with antibiotic-resistant pathogens such as MRSA and VRE is controllable to a low level by active detection and isolation of colonized and infected patients. Effective measures should be used to minimize the morbidity and mortality attributable to these largely preventable infections.

Modeling Transmission of Methicillin-ResistantStaphylococcus AureusAmong Patients Admitted to a Hospital

Objective:

To determine the impact of the screening test, nursing workload, handwashing rates, and dependence of handwashing on risk level of patient visit on methicillin-resistantStaphylococcus aureus(MRSA) transmission among hospitalized patients.

Setting:

General medical ward.

Methods:

Monte Carlo simulation was used to model MRSA transmission (median rate per 1,000 patient-days). Visits by healthcare workers (HCWs) to patients were simulated, and MRSA was assumed to be transmitted among patients via HCWs.

Results:

The transmission rate was reduced from 0.89 to 0.56 by the combination of increasing the sensitivity of the screening test from 80% to 99% and being able to report results in 1 day instead of 4 days. Reducing the patient-to-nurse ratio from 4.3 in the day and 6.8 at night to 3.8 and 5.7, respectively, reduced the number of nosocomial infections from 0.89 to 0.85; reducing the ratio to 1 and 1, respectively, further reduced the number of nosocomial infections to 0.32. Increases in handwashing rates by 0%, 10%, and 20% for high-risk visits yielded reductions in nosocomial infections similar to those yielded by increases in handwashing rates for all visits (0.89, 0.36, and 0.24, respectively). Screening all patients for MRSA at admission reduced the transmission rate to 0.81 per 1,000 patient-days from 1.37 if no patients were screened.

Conclusion:

Within the ranges of parameters studied, the most effective strategies for reducing the rate of MRSA transmission were increasing the handwashing rates for visits involving contact with skin or bodily fluid and screening patients for MRSA at admission. (Infect Control Hosp Epidemiol 2005;26:607- 615)

Epidemiology of Methicillin-Resistant Staphylococcus aureus Colonization in a Surgical Intensive Care Unit

Background.

Methicillin-resistant Staphylococcus aureus (MRSA) is a cause of healthcare-associated infections among surgical intensive care unit (ICU) patients, though transmission dynamics are unclear.

Objective.

To determine the prevalence of MRSA nasal colonization at ICU admission, to identify associated independent risk factors, to determine the value of these factors in active surveillance, and to determine the incidence of and risk factors associated with MRSA acquisition.

Design.

Prospective cohort study.

Setting.

Surgical ICU at a teaching hospital.

Patients.

All patients admitted to the surgical ICU.

Results.

Active surveillance for MRSA by nasal culture was performed at ICU admission during a 15-month period. Patients who stayed in the ICU for more than 48 hours had nasal cultures performed weekly and at discharge from the ICU, and clinical data were collected prospectively. Of 1,469 patients, 122 (8%) were colonized with MRSA at admission; 75 (61%) were identified by surveillance alone. Among 775 patients who stayed in the ICU for more than 48 hours, risk factors for MRSA colonization at admission included the following: hospital admission in the past year (1-2 admissions: adjusted odds ratio [aOR], 2.60 [95% confidence interval {CI}, 1.47-4.60]; more than 2 admissions: aOR, 3.56 [95% CI, 1.72-7.40]), a hospital stay of 5 days or more prior to ICU admission (aOR, 2.54 [95% CI, 1.49-4.32]), chronic obstructive pulmonary disease (aOR, 2.16 [95% CI, 1.17-3.96]), diabetes mellitus (aOR, 1.87 [95% CI, 1.10-3.19]), and isolation of MRSA in the past 6 months (aOR, 8.18 [95% CI, 3.38-19.79]). Sixty-nine (10%) of 670 initially MRSA-negative patients acquired MRSA in the ICU (corresponding to 10.7 cases per 1,000 ICU-days at risk). Risk factors for MRSA acquisition included tracheostomy in the ICU (aOR, 2.18 [95% CI, 1.13-4.20]); decubitus ulcer (aOR, 1.72 [95% CI, 0.97-3.06]), and receipt of enteral nutrition via nasoenteric tube (aOR, 3.73 [95% CI, 1.86-7.51]), percutaneous tube (aOR, 2.35 [95% CI, 0.74-7.49]), or both (aOR, 3.33 [95% CI, 1.13-9.77]).

Conclusions.

Active surveillance detected a sizable proportion of MRSA-colonized patients not identified by clinical culture. MRSA colonization on admission was associated with recent healthcare contact and underlying disease. Acquisition was associated with potentially modifiable processes of care.

Spread of a Methicillin-Resistant Staphylococcus aureus ST80-IV Clone in a Danish Community

Objective:

We report a community cluster of methicillin-resistant Staphylococcus aureus (MRSA) in Denmark with emphasis on routes of transmission and infection control measures. The objective is to extend knowledge of MRSA in a community setting where a nosocomial link could effectively be ruled out.

Design:

Population-based observational study from November 1997 until June 2003.

Setting:

North Jutland County, with approximately 495,000 inhabitants.

Subjects:

The cluster encompassed 46 individuals and 26 households.

Interventions:

Infection control measures included repeated visits to affected households by an infection control nurse who undertook screening for carriage among all household members and provided a program for decolonization.

Results:

The causal strain was identical to a newly described international clone, ST80; SSCmec type IV; and Panton–Valentine leukocidin positive. Plausible routes of transmission included household contact and contact at work, kindergarten, and school. We did not detect a nosocomial source or any secondary cases in hospitals. Transmission by healthcare contact outside the hospital was plausible for three cases. We found evidence that the clone was introduced on more than one occasion to immigrant families from the Middle East. A 5-day decolonization program was successful at first attempt in 15 of 16 households that could be evaluated.

Conclusions:

Despite the described infection control measures, we continued to see new cases, underlining a need for a national policy to contain MRSA in the community.

Colonization With Methicillin-resistant Staphylococcus aureus and Risk for Infection Among Asymptomatic Athletes: A Systematic Review and Metaanalysis

BACKGROUND

Athletes are a vulnerable population for methicillin-resistant Staphylococcus aureus (MRSA) infection. Our aim was to determine MRSA colonization in asymptomatic athletes and estimate the risk for subsequent MRSA infection.

METHODS

We searched the PubMed and EMBASE (through 29 October 2015) for studies on MRSA colonization among asymptomatic athletes.

RESULTS

The pooled prevalence of MRSA colonization among athletes was 6% (95% confidence interval [CI], 1,13), and it was higher in the United States (8%; 95% CI, 2,17). USA300 was the most common strain detected (22%), and 62% and 36% of isolates were resistant to clindamycin and trimethoprim/sulfamethoxazole, respectively. The prevalence of MRSA colonization among collegiate athletes reached 13% (95% CI, 4,25). Sports with the highest prevalence among collegiate athletes were wrestling (22%; 95% CI, 0,85), football (8%; 95% CI, 3,15) and basketball (8%; 95% CI, 0,28). The risk for MRSA skin and soft tissue infection within 3 months after documented colonization among MRSA-colonized athletes was significantly higher than for noncolonized athletes (relative risk = 7.37, 95% CI, [2.47,21.94]). Decolonization treatment among colonized athletes decreased significantly the risk for infection (relative risk reduction = 0.33; 95% CI, .03,4.28).

CONCLUSIONS

The prevalence of MRSA colonization among asymptomatic athletes is comparable to that among individuals with chronic illness, it is higher among collegiate athletes and can be twice that for patients in intensive care units. Importantly, colonization is associated with a >7-fold increase in the incidence of subsequent MRSA infection. Infection control and decontamination protocols for this population need to be studied and implemented with urgency.

Ability of cleaning-disinfecting wipes to remove bacteria from medical device surfaces

BACKGROUND

Nosocomial infections are a serious problem in health care facilities. Bacteria can be transferred from patient to patient via contaminated reusable medical devices and equipment.

METHODS

An anesthesia machine and objects representative of smooth and ridged machine knobs were contaminated with Staphylococcus aureus, Bacillus atrophaeus spores, and Clostridium sporogenes spores. The ability of 5 commercially available cleaning-disinfecting wipes to remove bacteria was compared with gauze soaked with water or bleach. Gauze soaked with water was used to determine the optimal wetness for bacteria removal, which was then used to evaluate the efficacy of the wipe ingredients.

RESULTS

All of the wipes cleaned the device surfaces significantly better than the no wipe control. Some wipes performed equally well as gauze with water, whereas others performed worse. Overall, the wipe containing sodium hypochlorite was the most effective at removing bacteria. When the wipe ingredients were re-evaluated using the determined optimal wipe wetness on gauze, their effectiveness at cleaning S aureus, but not spores, significantly improved.

CONCLUSION

Physically removing bacteria from device surfaces with water was often as effective as the cleaning-disinfecting wipes. Of the wipe active ingredients evaluated, sodium hypochlorite was the most effective overall. The wetness of the wipes may also play a role in their effectiveness.

Screening for methicillin-resistant Staphylococcus aureus colonization using sponges

OBJECTIVE Nasal swab culture is the standard method for identifying methicillin-resistant Staphylococcus aureus (MRSA) carriers. However, this method is known to miss a substantial portion of those carrying MRSA elsewhere. We hypothesized that the additional use of a sponge to collect skin culture samples would significantly improve the sensitivity of MRSA detection. DESIGN Hospitalized patients with recent MRSA infection were enrolled and underwent MRSA screening of the forehead, nostrils, pharynx, axilla, and groin with separate swabs and the forehead, axilla, and groin with separate sponges. Staphylococcal cassette chromosome mec (SCCmec) typing was conducted by polymerase chain reaction (PCR). PATIENTS A total of 105 MRSA patients were included in the study. RESULTS At least 1 specimen from 56.2% of the patients grew MRSA. Among patients with at least 1 positive specimen, the detection sensitivities were 79.7% for the swabs and 64.4% for the sponges. Notably, 86.4% were detected by a combination of sponges and nasal swab, and 72.9% were detected by a combination of pharyngeal and nasal swabs, whereas only 50.9% were detected by nasal swab alone (P<0.0001 and P=0.0003, respectively). Most isolates had SCCmec type II (59.9%) and IV (35.7%). No correlation was observed between the SCCmec types and collection sites. CONCLUSION Screening using a sponge significantly improves MRSA detection when used in addition to screening with the standard nasal swab.

Risk factors for meticillin-resistant Staphylococcus aureus colonization in dialysis patients: a meta-analysis

BACKGROUND

Patients on dialysis are particularly vulnerable to meticillin-resistant Staphylococcus aureus (MRSA) infections and MRSA colonization is associated with increased risk for severe infections in this population.

AIM

Determination of risk factors for MRSA colonization among dialysis patients.

METHODS

This is a systematic review and meta-analysis of studies reporting risk factors of MRSA colonization. We performed a PubMed and EMBASE literature search to identify all studies on risk factors for MRSA colonization among patients undergoing dialysis treatment. Previous hospitalization, type of dialysis access, comorbid conditions, dialysis vintage, gender, length of time on dialysis, and previous antibiotic use were extracted and assessed for possible association with MRSA colonization in this population.

FINDINGS

Ten out of 8252 articles, presenting data on 2364 dialysis patients, were included. We found that hospitalization within the previous 12 months [odds ratio (OR): 1.93; 95% confidence interval (CI): 1.04-3.58] and the use of temporary dialysis access (relative risk: 1.66; 95% CI: 1.06-2.60) were associated with a significantly higher risk of MRSA colonization. MRSA carriage was associated with lower serum albumin levels compared to non-carriage (OR: 0.8; 95% CI: 0.68-0.95) and was higher among patients with chronic lung disease (OR: 2.16; 95% CI: 1.04-4.51). There were no data on patients undergoing peritoneal dialysis.

CONCLUSION

Active surveillance approaches, including potential decolonization strategies, are suggested to focus on these subgroups of haemodialysis patients with hospitalization within the previous year, temporary dialysis access, lower serum albumin levels, and chronic lung disease comorbidity.

Molecular dissection of phage lysin PlySs2: integrity of the catalytic and cell wall binding domains is essential for its broad lytic activity

The novel phage lysin PlySs2, is reported to be highly active against various bacteria, including staphylococci, streptococci and Listeria. However, the molecular mechanisms underlying its broad lytic spectrum remain to be established. In the present study, the lytic activity of the catalytic domain (CD, PlySc) and binding specificity of the cell wall binding domain (CBD, PlySb) of PlySs2 were examined. Our results showed that PlySc alone maintains very limited lytic activity. Enhanced green fluorescent protein (EGFP)-fused PlySb displayed high binding affinity to the streptococcal strains tested, including S. suis, S. dysgalactiae, and S. agalactiae, but not staphylococci, supporting its utility as a good CBD donor for streptococcal-targeted lysin engineering. EGFP-fused intact PlySs2 similarly displayed high affinity for streptococci, but not staphylococci. Notably, four truncated PlySb fragments showed no binding capacity. These findings collectively indicate that integrity of the PlySc and PlySb domains is an essential determinant of the broad lytic activity of PlySs2.

Risk Factors for Methicillin-Resistant Staphylococcus Aureus Carriage in Residents of German Nursing Homes

Objectives:

To determine the prevalence of and the risk factors for methicillin-resistant Staphylococcus aureus (MRSA) carriage in nursing home residents in the Rhine-Neckar region of southern Germany.

Design:

Point-prevalence survey.

Setting:

Forty-seven nursing homes in the region.

Participants:

All residents of the approached nursing homes who agreed to participate.

Methods:

After informed consent was obtained, all participants had their nares swabbed, some personal data collected, or both. All swabs were examined for growth of MRSA All S. aureus isolates underwent oxacillin susceptibility testing and polymerase chain reaction for demonstration of the meek gene. All MRSA isolates were typed using pulsed-field gel electrophoresis after digestion with SmaI.

Results:

Swabs from 3,236 nursing home residents yielded 36 MRSA strains, contributing to a prevalence rate of 1.1%. Significant risk factors for MRSA carriage in the multivariate analysis were the presence of wounds or urinary catheters, limited mobility, admission to a hospital during the preceding 3 months, or stay in a medium-size nursing home. One predominant MRSA strain could be detected in 30 of the 36 MRSA carriers.

Conclusions:

The prevalence of MRSA in German nursing homes is still low. These residents seemed to acquire their MRSA in the hospital and transfer it to their nursing home. Apart from well-known risk factors for the acquisition of MRSA we identified the size of the nursing home as an independent risk factor. This might be due to an increased use of antimicrobials in nursing homes of a certain size.

Occurrence of Co-colonization or Co-Infection with Vancomycin-Resistant Enterococci and Methicillin-ResistantStaphylococcus aureusin a Medical Intensive Care Unit

Objective:

To determine the occurrence of co-colonization or co-infection with VRE and MRSA among medical patients requiring intensive care.

Design:

Prospective, single-center, observational study.

Setting:

A 19-bed medical ICU in an urban teaching hospital.

Patients:

Adult patients requiring at least 48 hours of intensive care and having at least one culture performed for microbiologie evaluation.

Results:

Eight hundred seventy-eight consecutive patients were evaluated. Of these patients, 402 (45.8%) did not have microbiologie evidence of colonization or infection with either VRE or MRSA 355 (40.4%) were colonized or infected with VRE, 38 (4.3%) were colonized or infected with MRSA, and 83 (9.5%) had co-colonization or co-infection with VRE and MRSA. Multiple logistic regression analysis demonstrated that increasing age, hospitalization during the preceding 6 months, and admission to a long-term-care facility were independently associated with colonization or infection due to VRE and co-colonization or co-infection with VRE and MRSA. The distributions of positive culture sites for VRE (stool, 86.7%; blood, 6.5%; urine, 4.8%; soft tissue or wound, 2.0%) and for MRSA (respiratory secretions, 34.1%; blood, 32.6%; urine, 17.1%; soft tissue or wound, 16.2%) were statistically different (P< .001).

Conclusions:

Co-colonization or co-infection with VRE and MRSA is common among medical patients requiring intensive care. The recent emergence of vancomycin-resistantStaphylococcus aureusand the presence of a patient population co-colonized or co-infected with VRE and MRSA support the need for aggressive infection control measures in the ICU.

Exploiting what phage have evolved to control gram-positive pathogens

In the billion years that bacteriophage (or phage) have existed together with bacteria the phage have evolved systems that may be exploited for our benefit. One of these is the lytic system used by the phage to release their progeny from an infected bacterium. Endolysins (or lysins) are highly evolved enzymes in the lytic system produced to cleave essential bonds in the bacterial cell wall peptidoglycan for progeny release. Small quantities of purified recombinant lysin added externally to gram-positive bacteria results in immediate lysis causing log-fold death of the target bacterium. Lysins have now been used successfully in a variety of animal models to control pathogenic antibiotic resistant bacteria found on mucosal surfaces and in infected tissues. The advantages over antibiotics are their specificity for the pathogen without disturbing the normal flora, the low chance of bacterial resistance, and their ability to kill colonizing pathogens on mucosal surfaces, a capacity previously unavailable. Lysins therefore, may be a much-needed anti-infective (or enzybiotic) in an age of mounting antibiotic resistance.

Engineered bacteriophage lysins as novel anti-infectives

Bacteriophage lysins, the highly evolved specific peptidoglycan hydrolases, have long been demonstrated to be effective enzybiotics in various infectious models. The modular structure of lysins makes it possible to design bioengineered lysins that have desired properties, such as higher activity, or broader killing spectrum. Moreover, lysins can even be engineered to kill Gram-negative bacterial pathogens from without, a property that is not present in natural lysins. In this era of ever increasing multidrug resistant pathogens, engineered lysins represent a new class of enzybiotics that are powerful and readily available to fight antimicrobial resistance.

A prospective observational study of the prevalence and risk factors for colonization by antibiotic resistant bacteria in patients at admission to hospital in Singapore

Background

Drug resistant organisms pose an increasing threat to the successful treatment of common infections. Understanding colonization patterns of these bacteria is important for effective antibiotic treatment and infection control guidelines.

Methods

A prospective observational study was performed to determine the prevalence of colonization with extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-E), methicillin-resistant Staphylococcus aureus (MRSA), and vancomycin-resistant Enterococcus (VRE) among patients admitted via the emergency department to a public tertiary hospital in Singapore. Anterior nares, groin, axillary and rectal swabs were collected at admission and cultured using standard bacteriological techniques. Clinical data including healthcare contact within the past 12 months and recent antibiotic use was collected and analyzed using a logistic regression model.

Results

1006 patients were screened. 124 (12.4%) were colonized by ESBL-E, 18 (1.8%) by MRSA while no VRE was detected. Antibiotic use within the past month was the only significant predictor for ESBL-E colonization in the regression model, with an adjusted odds ratio (AOR) of 2.58 (1.04 to 6.42). In participants recently prescribed antibiotics and hospitalized in the previous 3 months, 29.4% were colonized by ESBL-E. This represented 20.2% of the total ESBL-E burden, and ESBL-E was also detected in 6.3% of participants with no healthcare contact. Hospitalization and outpatient hospital visits predicted MRSA colonization in the univariate analysis. Neither was statistically significant in the logistic regression model, with AORs for MRSA colonization following hospitalization in the past 3 and 12 months of 3.81 [95% CI 0.84-17.28] and 3.48 [0.64-18.92] respectively.

Conclusion

A high prevalence of colonization with ESBL-E was evident among patients at admission, even in the absence of recent antibiotic use or contact with healthcare.

Intestinal carriage of methicillin-resistant Staphylococcus aureus in nasal MRSA carriers hospitalized in the neonatal intensive care unit

BACKGROUND

The current data regarding the correlation between the methicillin-resistant Staphylococcus aureus (MRSA) clones carried in the nasal cavity and digestive tract are inadequate.

METHODS

MRSA strains were isolated from both the feces and nasal swabs of 21 nasal-MRSA carriers ranging from 10 to 104 days of age treated at the neonatal intensive care units of two hospitals. The molecular epidemiological characteristics of the isolates were determined: multilocus sequence types, spa-types, staphylococcal cassette chromosome mec (SCCmec) types, carriage of four exotoxin genes, and genes contained in commercially available kit.

RESULTS

The feces of all nasal carriers contained MRSA at levels ranging from 4.0 × 10(2) to 2.8 × 10(8) colony forming units/g feces. The MRSA clones isolated from the feces and the nasal swabs of each patient were the same. Four MRSA clones, clonal complex (CC) 8-SCCmec IVl, CC8-SCCmec IVb, CC1-SCCmec IVa and CC5-SCCmec IIa were identified from 21 patients. All CC8-SCCmec IVl strains and one of three CC5-SCCmec IIa strains carried the toxic shock syndrome toxin gene.

CONCLUSIONS

The feces of tested MRSA carriers contained the same MRSA clones as the nasal isolates in considerable amounts, suggesting that more careful attention should be paid for the handling of excrement in the case of newborn babies or infants than that of adults.

Risk factors for intensive care unit acquired nasal colonization of MRSA and its impact on MRSA infection

OBJECTIVE

We aimed to determine the risk factors of methicillin-resistant Staphylococcus aureus (MRSA) colonization, and the impact of colonization on MRSA infection to evaluate the necessity of MRSA survey program in intensive care units (ICUs) in Turkey.

METHODS

The patients hospitalized in medical and neurosurgical ICUs longer than 24 hr were included into the study. To determine anterior nares MRSA colonization, swabs were taken from each patient in the first 48 hr, and followed by once a week till discharge from ICUs.

RESULTS

During the one-year follow-up period, the number of the hospitalized patients who spent more than 24 hr in ICUs was 195 of 372 and 85 of 619 in medical and neurosurgical ICUs, respectively. Totally, 23 out of 280 patients (14 from medical ICU, 9 from neurosurgical ICU) were colonized with MRSA, and 11 out of 23 colonized patients were accepted as ICU-acquired infection. The duration of ICU hospitalization in patients with ICU-acquired MRSA colonization was found to be longer than the noncolonized patients (18 days vs. 8 days, P value < 0.001). The presence of gastrostomy and femoral catheter were determined as risk factors for ICU-acquired MRSA colonization. The percentages of MRSA infection in patients with and without MRSA colonized were 8.6% and 1.1%, respectively (P value: 0.009).

CONCLUSION

The presence of gastrostomy and femoral catheter, and the duration of ICU hospitalization were found to be related with ICU-acquired MRSA colonization. Also, MRSA nares colonization increased the rates of both MRSA infection and ICU hospitalization.

Health care workers' hand contamination levels and antibacterial efficacy of different hand hygiene methods used in a Vietnamese hospital

BACKGROUND

Handwashing with soap or another antisepsis disinfectant solution is a common practice in Vietnam, but the availability and quality of tap water is unpredictable. We assessed the risk for hand contamination and compared the efficacy of 5 hand hygiene methods in a tertiary Vietnamese hospital.

METHODS

Five fingertip imprints of the dominant hand of 134 health care workers (HCWs) were sampled to establish the average bacterial count before and after hand hygiene action using (1) alcohol-based handrub (ABHR), (2) plain soap and water handwashing with filtered and unfiltered water, or (3) 4% chlorhexidine gluconate hand antisepsis with filtered and unfiltered water.

RESULTS

Average bacterial contamination of hands before hand hygiene was 1.65 log(10). Acinetobacter baumannii, Klebsiella pneumoniae, and Staphylococcus aureus were the most commonly isolated bacterial pathogens. The highest average count before hand hygiene was recovered from HCWs without direct patient contact (2.10 ± 0.11 log(10)). Bacterial counts were markedly reduced after hand hygiene with ABHR (1.4 log(10); P < .0001) and 4% chlorhexidine gluconate with filtered water (0.8 log(10); P < .0001). Use of unfiltered water was associated with minimal nonsignificant bacterial reduction.

CONCLUSIONS

HCWs carry high levels of bacteria on their dominant hand, even without direct patient contact. ABHR as an additional step may overcome the effect of high bacterial counts in unfiltered water when soap and water handwashing is indicated.

Prevalence of Staphylococcus aureus methicillin-sensitive and methicillin-resistant nasal and pharyngeal colonization in outpatients in Lebanon

BACKGROUND

There is an increasing concern about methicillin-resistant Staphylococcus aureus (MRSA) infections in the community. This study aimed to evaluate the rate of S aureus nasopharyngeal colonization in outpatients as the primary endpoint, and also to study the impact of several possible risk factors, including recent hospitalization, recent surgical procedures, and antibiotic intake.

METHODS

A total of 1,526 consecutive outpatients underwent surveillance cultures after completing a questionnaire. Isolated S aureus strains were tested for antibiotic susceptibility. The Pearson χ(2) test was used for statistical analysis. The differences were considered to be statistically significant at a P value <.05.

RESULTS

Out of the 1,526 outpatients tested, 133 (8.7%) carried S aureus in the nose and/or throat. Only 2 of those cases were MRSA, and both were isolated from the nose. One hundred thirty-one patients had methicillin-sensitive S aureus, 13 with simultaneous carriage in the nose and throat. Among the risk factors, a relative working in health care, presence of an intravascular device, recent dental procedure, and health club use were significantly associated with an increased risk of S aureus colonization, with P values of .00, .02, .04, and .00, respectively, calculated by the χ(2) test.

CONCLUSIONS

The prevalence of MRSA is still low in our study population within the Lebanese community. The only significant risk factors playing a role in increasing the carriage of S aureus were related to health care exposure.

Prevalence and antibiotic resistance pattern of methicillin-resistant Staphylococcus aureus from an orthopaedic hospital in Nigeria

Patients with surgical wounds have been reported to be at high risk of MRSA carriage and infection. The prevalence and antibiotic resistance pattern of this organism in the orthopaedic ward of Ahmadu Bello University Teaching Hospital (ABUTH), Zaria-Nigeria, a 547-bed Nigerian hospital, were thus studied. A total of 185 isolates of Staphylococcus aureus were confirmed from 217 samples taken from the orthopaedic wards of the hospital using standard isolation methods. Out of these, 44 (23.8%) were from the wounds of patients and 70 (37.8%) from the skin. The remaining 65 (35.1%) and 6 (3.2%) were from their beds and the atmospheric air, respectively. Out of these, 33 (75%), 36 (51.4%), and 48 (73.8%) from wounds, skin, and bed, respectively, were found to be methicillin-resistant Staphylococcus aureus (MRSA) using the disc-sensitive test methods. None was detected from the atmosphere. The antibiotic susceptibility pattern results showed the level of resistance to be ampicillin 100% in all the three sites, pefloxacin 90.9%, 72.2%, 66.7%, ceftriaxone 69.7%, 72.2%, 70.8%, gentamicin 54.5%, 52.8%, 37.5%, and ciprofloxacin 51.5%, 47.2%, 35.4% at the wound, skin, and bed sites, respectively. Results confirm that MRSA continues to pose a threat to the hospitalized patients, especially those with bone and wound infections.

Risk factors for community-associated methicillin-resistant Staphylococcus aureus colonisation in a large metropolitan area in Greece: An epidemiological study using two case definitions

The aim of this study was to evaluate the epidemiology and characteristics and to identify modifiable risk factors for community-associated (CA) MRSA colonisation in a region with high prevalence. A large patient population (n=2280) from two tertiary care centres in Athens (Greece) was evaluated. Demographics and potential risk factors for CA-MRSA colonisation were recorded prospectively. Presence of the Panton-Valentine Leukocidin (PVL) toxin and mecA gene was determined in all MRSA isolates. Two definitions for CA-MRSA were applied. Univariate and multivariate analyses to identify predictors of previously unknown CA-MRSA colonisation were performed. In total, 120 (5.3%) MRSA carriers were identified; in 67 the isolates were classified as CA-MRSA using criteria based on the CDC definition, compared with 35 based on a definition including PVL toxin positivity. Factors significantly associated with previously unknown CA-MRSA carriage (CDC definition) included being a child or adolescent (OR=3.6, 95% CI 1.5-8.6), belonging to the family of an index case (OR=2.4, 95% CI 1.2-4.8), and presence of any co-morbidity (OR=1.7, 95% CI 1.04-2.8) or chronic skin disease (OR=3.6, 95% CI=2.2-6.1). In multivariate analysis, presence of any co-morbidity was the only significant predictor (OR=4.9, 95% CI 1.07-22.5; P=0.04). No easily modifiable risk factor for previously unknown CA-MRSA colonisation was identified. The CDC-based epidemiological definition for CA-MRSA appears to be more sensitive in detection of CA-MRSA colonisation than a purely molecular definition based on presence of the PVL gene.

Dutch guideline on the laboratory detection of methicillin-resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) has rapidly emerged worldwide, affecting both healthcare and community settings, and intensive livestock industry. The efficient control of MRSA strongly depends on its adequate laboratory detection. This guideline provides recommendations on the appropriate use of currently available diagnostic laboratory methods for the timely and accurate detection of MRSA in patients and healthcare workers. Herewith, it aims to standardise and improve the diagnostic laboratory procedures that are used for the detection of MRSA in Dutch medical microbiology laboratories.

Risk factors for development of methicillin-resistant Staphylococcus aureus infection among colonized patients

BACKGROUND

This study was conducted to identify clinical factors associated with development of infection caused by methicillin-resistant Staphylococcus aureus (MRSA) among hospitalized patients with nasal MRSA colonization.

METHODS

We conducted a prospective cohort with nested case-control study at a 672-bed, public, academic hospital in Dallas, Texas. The study duration was from January 1, 2008, to July 28, 2009. From the cohort of patients who had presence of nasal colonization with MRSA at admission, we identified patients who developed subsequent infection with MRSA during a 3-month period. We compared these patients (cases) with colonized patients who remained uninfected (controls; 2 controls per case). We collected demographic and clinical data and performed statistical analyses.

RESULTS

During the 19-month study period, 426 patients were found to have nasal colonization with MRSA. Of these, 36 (8.5%) developed a subsequent infection with MRSA within 3 months. When these 36 cases were compared with 72 controls, the factors independently associated with the development of subsequent infection were development of pressure ulcer during hospital stay (adjusted odds ratio, 5.82; 95% confidence interval: 2.21-15.31; P value=.000) and preadmission steroid therapy (adjusted odds ratio, 13.2; 95% confidence interval: 2.44-70.97; P value=.003).

CONCLUSION

History of steroid therapy prior to admission and development of pressure ulcer are associated with increased risk of subsequent MRSA infection in patients nasally colonized with MRSA.

A trial of discontinuation of empiric vancomycin therapy in patients with suspected methicillin-resistant Staphylococcus aureus health care-associated pneumonia

Healthcare-associated pneumonia (HCAP) guidelines recommend de-escalating initial antibiotic therapy based on results from lower-respiratory-tract cultures. In the absence of adequate lower respiratory cultures, physicians are sometimes reluctant to discontinue empirical vancomycin, which is given for suspected methicillin-resistant Staphylococcus aureus (MRSA) HCAP. We evaluated a strategy of discontinuing vancomycin if both nasal and throat cultures were negative for MRSA when lower-respiratory-tract cultures were not available. An antimicrobial stewardship team identified patients receiving empirical vancomycin for suspected or proven HCAP but for whom adequate lower-respiratory-tract cultures were not available. Nasal and throat swab specimens were obtained and plated on MRSA selective media. If both nasal and throat MRSA cultures were negative, the stewardship team recommended discontinuation of empirical vancomycin. Demographic and clinical aspects, a clinical pulmonary infection score (CPIS) on the day of the stewardship recommendation, and mortality of patients for whom vancomycin was discontinued were obtained by retrospective chart review. A convenience sample of 91 patients with nasal and throat cultures negative for MRSA in the absence of adequate respiratory cultures had empirical vancomycin therapy discontinued. A retrospective review revealed that 88 (97%) patients had a CPIS of ≤6 on the day of the stewardship recommendation. In-hospital mortality (7.7%) was similar to that of a previous study of de-escalation of antibiotics in pneumonia patients without adequate cultures. In the absence of adequate lower-respiratory-tract cultures, it is reasonable to discontinue empirical vancomycin HCAP therapy in patients with negative MRSA nasal and throat cultures and a CPIS of <6.

Triple swabbing allows sensitive MRSA detection in dermatologic patients of a university tertiary care hospital

BACKGROUND

To optimize preventive measures to control MRSA, we investigated retrospectively the suitability of a multiple site screening model and the optimal sampling technique to detect MRSA in a university-based phlebology and skin cancer center in Germany.

PATIENTS AND METHODS

During 4.5 years samples of 3 712 inpatients in a dermatologic department were analyzed for MRSA by conventional microbiologic cultures and in parallel by PCR. Samples were taken from nares, wounds and skin lesions.

RESULTS

MRSA was detected in 60 inpatients (1.6%). 268 of 7 269 (3.7%) samples at admission and during hospital stay were found positive ñ 96 (35.8%) of these were swabs of nares, 59 (22.0%) surveillance swabs, 53 (19.8%) wound swabs and 42 (15.7%) from other dermatologic lesions. Twenty-five of 60 patients (41.7%) were found positive only in the nares, 10 (16.7%) patients only in wounds and 4 (6.7%) patients only in lesions. 166 (61.9%) of all positive culture samples became positive 24 hours after cultivation, 86 (32.1%) after 48 hours, and 16 (6.0%) after 72 hours.

CONCLUSIONS

Highest sensitivity to detect MRSA can be reached by combining three swabs: nares, wounds and skin lesions (ìtriple-testî). Culture of screening specimens for 72 hours is recommended.

Nasal swab screening for methicillin-resistant Staphylococcus aureus--how well does it perform? A cross-sectional study

OBJECTIVE

To determine the proportion of methicillin-resistant Staphylococcus aureus (MRSA) detections identified by nasal swabbing using agar culture in comparison with multiple body site testing using agar and nutrient broth culture.

DESIGN

Cross-sectional study.

PATIENTS

Adult patients admitted to 36 general specialty wards of 2 large hospitals in Scotland.

METHODS

Patients were screened for MRSA via multiple body site swabs (nasal, throat, axillary, perineal, and wound/invasive device sites) cultured individually on chromogenic agar and pooled in nutrient broth. Combined results from all sites and cultures provided a gold-standard estimate of true MRSA prevalence.

RESULTS

This study found that nasal screening performed better than throat, axillary, or perineal screening but at best identified only 66% of true MRSA carriers against the gold standard at an overall prevalence of 2.9%. Axillary screening performed least well. Combining nasal and perineal swabs gave the best 2-site combination (82%). When combined with realistic screening compliance rates of 80%-90%, nasal swabbing alone probably detects just over half of true colonization in practice. Swabbing of clinically relevant sites (wounds, indwelling devices, etc) is important for a small but high-prevalence group.

CONCLUSIONS

Nasal swabbing is the standard method in many locations for MRSA screening. Its diagnostic efficiency in practice appears to be limited, however, and the resource implications of multiple body site screening have to be balanced against a potential clinical benefit whose magnitude and nature remains unclear.

Chlorhexidine body washing to control antimicrobial-resistant bacteria in intensive care units: a systematic review

PURPOSE

Infections caused by antimicrobial-resistant bacteria (AMRB) are increasing worldwide, especially in intensive care units (ICUs). Chlorhexidine body washing (CHG-BW) has been proposed as a measure to limit the spread of AMRB. We have systematically assessed the evidence on the effectiveness of CHG-BW in reducing colonization and infection with AMRB in adult ICU patients.

METHODS

PubMed, Embase, CINAHL, and OpenSigle databases were searched using synonyms for "intensive care unit," "hospital," and "chlorhexidine." All potentially relevant articles were examined by two independent reviewers. Inclusion was limited to studies with ICU patients as domain, providing outcomes related to colonization or infection with AMRB. Data from 16 studies were extracted; 9 were excluded because of assessed high risk of bias or inadequate analyses. The remaining studies differed markedly in (co-)interventions and case mix, which precluded pooling of data in a formal meta-analysis.

RESULTS

Incidences of MRSA acquisition were reduced significantly in three studies in which this was the primary endpoint. Significant reduction in MRSA infection rates was observed in only one of five studies. Carriage and bacteremia rates of VRE were assessed in one study, and both significantly declined. There were hardly any data on the effects of CHG-BW on antibiotic-resistant gram-negative bacteria (ARGNB).

CONCLUSIONS

CHG-BW may be effective in preventing carriage, and possibly bloodstream infections, with MRSA and VRE in different ICU settings. As CHG-BW protocols, co-interventions and case mix varied widely, attribution of these effects to CHG-BW alone should be done with care. Evidence that CHG-BW reduces carriage of or infections with ARGNB is lacking.

Prevalence of methicillin-resistant Staphylococcus aureus based on culture and PCR in inpatients at a tertiary care center in Tokyo, Japan

We investigated active screening for colonization with methicillin-resistant Staphylococcus aureus (MRSA) on admission and weekly follow-up surveillance after admission to a tertiary care center (TCC) between June 2007 and 31 December 2007. Eleven percent (30/267) of patients were found to be positive for MRSA by polymerase chain reaction (PCR) and/or culture on admission; 5% (12/267) became positive during the TCC stay. The major primary diagnoses in MRSA-positive patients were pneumonia and cerebrovascular diseases. Twenty-two (52%) of 42 patients were found to be MRSA positive by both PCR and culture, compared with 19 (45%) of 42 who were PCR positive and culture negative. These findings suggest that active surveillance with PCR is highly sensitive and useful for the detection of MRSA colonization. To our knowledge, this is the first report of active surveillance of MRSA by PCR and bacterial culture in critically ill inpatients in Japan.

Epidemiology and clinical features of methicillin-resistant Staphylococcus aureus in the University Hospital, Jeddah, Saudi Arabia

OBJECTIVE

To describe the prevalence, demography and clinical characteristics of patients who were colonized or infected with methicillin-resistant Staphylococcus aureus (MRSA) in 1998 at King Abdulaziz University Hospital, Jeddah, Saudi Arabia.

PATIENTS AND METHODS

Results of MRSA-positive cultures of clinical specimens obtained as part of investigations for suspected infections were retrieved from the King Abdulaziz University Hospital Infection Control Department's records. Charts of patients were reviewed.

RESULTS

Of 292 S aureus isolates identified, 111 (38%) were MRSA, or 6.0 MRSA isolates/1000 admissions, which represented a marked increase over MRSA prevalence in 1988 (less than 2%). Nosocomial acquisition occurred in 74.8% of isolates. All age groups were affected, but 45.9% of patients were in the 'extremes of age' group (younger than one or older than 60 years of age). The prevalence was highest in the medical ward (27%), followed by the paediatrics combined medical and surgical ward (20.7%), the outpatient department (18%), the adult surgical ward (17.1%) and the intensive care units (17.1%). Two-thirds (66.7%) of cases represented infection and the remainder represented colonization. Surgical wounds (31.1%), the chest (27%) and endovascular catheters (20.3%) were the most common sites of infection. Bacteremia occurred in 27% of patients. Local signs (68.9%) and fever (60.8%) were the most common clinical manifestations. Respiratory distress and septic shock occurred in 28.4% and 6.8% of cases, respectively. Of 74 patients with MRSA infection and 37 patients with MRSA colonization, 91.9% and 56.8% received antibiotics in the preceding six weeks, respectively (P<0.0001). The total mortality of patients with MRSA infection was 60.8%; 37.8% of deaths were the result of MRSA infection and 23% were the result of other diseases.

CONCLUSIONS

The prevalence of MRSA is high and rapidly increasing at King Abdulaziz University Hospital, as it is worldwide. Control measures to prevent the spread of MRSA in hospitals should continue with reinforcement of hygienic precautions and development of policies to restrict the use of antibiotics.

Prevalence of methicillin-resistant Staphylococcus aureus in a Canadian inner-city shelter

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) colonization is increasingly of concern in community settings. However, despite a recent outbreak in Calgary, Alberta, data on the prevalence of MRSA in Canadian communities are lacking. Globally, few studies have been performed in high-risk groups such as inner-city populations.

METHODS

A cross-sectional study of the prevalence of MRSA among residents and staff at three Ottawa, Ontario, shelters was conducted. All participants completed a questionnaire, and provided nasal swabs as well as one of rectal, anal or groin swabs.

RESULTS

Among 84 participants, the prevalence of MRSA colonization was 2.4%. Among the resident subgroup, the prevalence was 4.5%, while no MRSA isolates were found among 40 staff participants. All isolates were USA100 (CMRSA-2) subtypes.

CONCLUSIONS

The prevalence of MRSA colonization among residents is higher than baseline population rates, but is consistent with other inner-city populations. Although community outbreaks of USA300 and USA400 strains are increasingly reported, movement of nosocomial strains (ie, USA100 [CMRSA-2]) into communities remains an important avenue in the spread of MRSA and underscores the importance of nosocomial MRSA control.

Staphylococcus aureus carriage among GPs in The Netherlands

BACKGROUND

The extent to which GPs serve as a reservoir for antibiotic-resistant Staphylococcus aureus is unknown and not well studied.

AIM

To determine the prevalence of nasal S. aureus carriage among GPs in the Netherlands, as well as the antimicrobial resistance and the genotypes of isolated S. aureus.

DESIGN OF STUDY

Observational, point-prevalence, and cross-sectional study.

SETTING

GPs attending the annual conference of the Dutch College of General Practitioners in 2006.

METHOD

Nasal swabs were randomly taken from 395 GPs and analysed for the presence of S. aureus. Antimicrobial susceptibility was determined by a microbroth dilution method and the genotypes by spa typing, which was associated with multilocus sequence typing.

RESULTS

Of the GPs, 129/395 (33%; 95% confidence interval [CI] = 28 to 37%) were carriers of S. aureus. No meticillin-resistant S. aureus (MRSA) was found. Resistance was observed to penicillin (71%; 95% CI = 63 to 79%), fusidic acid (7%; 95% CI = 3 to 13%), and clarithromycin (6%; 95% CI = 3 to 12%). In 72% of the isolates, an MRSA-related genotype of S. aureus was found.

CONCLUSION

The low antibiotic resistance found among S. aureus of GPs suggests that GPs are not a reservoir of antibiotic-resistant S. aureus strains. The relatively high resistance to fusidic acid, which has not previously been described in the Netherlands and is mostly because of antibiotic use, suggests that patients infect GPs and not the other way round. GPs may be at risk for nasal carriage of S. aureus with an MRSA-related genotype.

Staphylococcus aureus nasal colonization and subsequent infection in intensive care unit patients: does methicillin resistance matter?

BACKGROUND

Staphylococcus aureus is an important cause of infection in intensive care unit (ICU) patients. Colonization with methicillin-resistant S. aureus (MRSA) is a risk factor for subsequent S. aureus infection. However, MRSA-colonized patients may have more comorbidities than methicillin-susceptible S. aureus (MSSA)-colonized or noncolonized patients and therefore may be more susceptible to infection on that basis.

OBJECTIVE

To determine whether MRSA-colonized patients who are admitted to medical and surgical ICUs are more likely to develop any S. aureus infection in the ICU, compared with patients colonized with MSSA or not colonized with S. aureus, independent of predisposing patient risk factors.

DESIGN

Prospective cohort study.

SETTING

A 24-bed surgical ICU and a 19-bed medical ICU of a 1,252-bed, academic hospital.

PATIENTS

A total of 9,523 patients for whom nasal swab samples were cultured for S. aureus at ICU admission during the period from December 2002 through August 2007.

METHODS

Patients in the ICU for more than 48 hours were examined for an ICU-acquired S. aureus infection, defined as development of S. aureus infection more than 48 hours after ICU admission.

RESULTS

S. aureus colonization was present at admission for 1,433 (27.8%) of 5,161 patients (674 [47.0%] with MRSA and 759 [53.0%] with MSSA). An ICU-acquired S. aureus infection developed in 113 (2.19%) patients, of whom 75 (66.4%) had an infection due to MRSA. Risk factors associated with an ICU-acquired S. aureus infection included MRSA colonization at admission (adjusted hazard ratio, 4.70 [95% confidence interval, 3.07-7.21]) and MSSA colonization at admission (adjusted hazard ratio, 2.47 [95% confidence interval, 1.52-4.01]).

CONCLUSION

ICU patients colonized with S. aureus were at greater risk of developing a S. aureus infection in the ICU. Even after adjusting for patient-specific risk factors, MRSA-colonized patients were more likely to develop S. aureus infection, compared with MSSA-colonized or noncolonized patients.

Prevention and control of health care-associated infections through improved hand hygiene

Determined actions are required to address the burden due to health care-associated infections worldwide and improve patient safety. Improving hand hygiene among health care workers is an essential intervention to achieve these goals. The World Health Organization (WHO) First Global Patient Safety Challenge, Clean Care is Safer Care, pledged to tackle the problem of health care-associated infection at its launch in 2005 and has elaborated a comprehensive set of guidelines for use in both developed and developing countries worldwide. The final version of the WHO Guidelines on Hand Hygiene in Health Care was issued in March 2009 and includes recommendations on indications, techniques, and products for hand hygiene. In this review, we discuss the role of hands in the transmission of health care-associated infection, the benefits of improved compliance with hand hygiene, and the recommendations, implementation strategies and tools recommended by WHO. We also stress the need for action to increase the pace with which these recommendations are implemented in facilities across India.

Infection Control in the Sonography Department

Knowledge of how to prevent healthcare-associated infections within the sonography department is an important step in providing quality care. Employing scientifically based preventative measures will ensure that the tools we use do not become vectors for the spread of pathogens that cause infections. These avoidable infections have not only an added financial cost to patients and the already burdened healthcare system but also physical and emotional costs to the patients we treat. Specific infection control guidelines for the sonography department are lacking, and the guidelines that are available are often based on proven infection control practiced in similar situations. Within this article are the applicable infection guidelines sonographers can use to provide safe quality care.

Higher prevalence of pharyngeal than nasal Staphylococcus aureus carriage in pediatric intensive care units

Sensitive detection of Staphylococcus aureus colonization is important for epidemiologic studies, infection control, and decolonization measures. We examined the sensitivity of nasal and pharyngeal sampling for S. aureus colonization in 331 children admitted to intensive care units. Pharyngeal screening was more sensitive than nasal screening (92.6% versus 63.1%, P < 0.0001).

Methicillin resistant Staphylococcus aureus in a Japanese community hospital: 5-year experience

Methicillin resistant Staphylococcus aureus (MRSA) is exceptionally critical to infection treatment and control in the health-care setting. MRSA has been detected at high levels in Japan, and the frequency of MRSA infection must be ascertained to provide a baseline with which to assess various infection control efforts. We studied MRSA infection rate at a general hospital in Japan in all 65,135 inpatients of Sendai Kousei Hospital from January 2004 to December 2008. MRSA's prevalence among strains of S. aureus and the rate of MRSA detection were studied. Identification of MRSA infection is according to the laboratory-based ward liaison surveillance. The minimal inhibitory concentrations (MICs) of vancomycin, teicoplanin, and arbekacin for the various isolates were determined. During the period studied, there were 621 MRSA-positive patients. MRSA prevalence among strains of S. aureus was 45.5% (621/1,365). The rate of MRSA detection in inpatients was 0.953/100 inpatients. Of the 621 patients from whom MRSA was isolated, 51 (8.2%) had an MRSA infection (MRSA infection rate 0.078/100 inpatients). MRSA was often detected from the respiratory tract, but this seldom led to infection, since many of those affected were merely carriers. MICs against MRSA was 0.5-4 μg/ml for vancomycin, 0.5-16 μg/ml for teicoplanin, and 0.5 to >16 μg/ml for arbekacin, with no tendency for tolerance observed for these drugs. Findings suggest that whereas MRSA remains prevalent, there is a low incidence of infection in a general hospital in Japan.

Bacteriophage endolysins: a novel anti-infective to control Gram-positive pathogens

Endolysins (or lysins) are highly evolved enzymes produced by bacteriophage (phage for short) to digest the bacterial cell wall for phage progeny release. In Gram-positive bacteria, small quantities of purified recombinant lysin added externally results in immediate lysis causing log-fold death of the target bacterium. Lysins have been used successfully in a variety of animal models to control pathogenic antibiotic-resistant bacteria found on mucosal surfaces and infected tissues. Their specificity for the pathogen without disturbing the normal flora, the low chance of bacterial resistance, and their ability to kill colonizing pathogens on mucosal surfaces, a capacity previously unavailable, make them ideal anti-infectives in an age of mounting resistance. Here we review the current literature showing the effectiveness of these enzymes in controlling a variety of infections.

Rapid MRSA test in exposed persons: costs and savings in hospitals

OBJECTIVE

To study a rapid Xpert polymerase chain reaction (PCR) method in detecting methicillin-resistant Staphylococcus aureus (MRSA) in patients and healthcare workers (HCW) exposed to MRSA, and to estimate savings associated to isolation or work restriction.

METHODS

A test set of four double (one for the growth and one for the rapid test) pre-wet swabs from the nose, throat, hands/wrists and perineum was studied by a growth method and by the Xpert MRSA test.

RESULTS

The total correspondence between the growth and the rapid test was 92.8%. The overall sensitivity, specificity, positive and negative predictive values were for the Xpert MRSA test: 87%, 99.6%, 68.5% and 99.9%, and for the growth test: 76%, 100%, 100%, and 99.8%, assuming a prevalence of MRSA of 0.01%. Among the MRSA positive persons, the Xpert and growth tests detected MRSA in 44.6% and 40% of nose samples, respectively, 38.2% and 45.5% throat samples, 30.8% and 11.5% hands/wrists samples, 44% and 38% perineum samples, and in 81.8% and 77.3% wound samples, respectively. By combining four anatomical sites, the detection rate increased to 87.5% by both methods. The cost for each Xpert and growth test was euro50 and euro6.25, respectively. The rapid test would save at least euro925 per exposed HCW and euro550 per patient that were MRSA negative.

CONCLUSION

The MRSA Xpert test is easy to perform, has a high negative predictive value, and may be used to control healthcare workers and patients exposed to MRSA. Sampling from multiple anatomical locations is recommended. Still, more then 10% of MRSA positive cases may not be found.