Acquisition and cross-transmission of Staphylococcus aureus in European intensive care units

Effect of single-patient room design on the incidence of nosocomial infection in the intensive care unit: a systematic review and meta-analysis

Background

Previous studies have yielded varying conclusions regarding the impact of single-patient room design on nosocomial infection in the intensive care unit (ICU). We aimed to examine the impact of ICU single-patient room design on infection control.

Methods

We conducted a comprehensive search of PubMed, Embase, the Cochrane Library, Web of Science, CNKI, WanFang Data, and CBM databases from inception to October 2023, without language restrictions. We included observational cohort and quasi-experimental studies assessing the effect of single- versus multi-patient rooms on infection control in the ICU. Outcomes measured included the nosocomial infection rate, incidence density of nosocomial infection, nosocomial colonization and infection rate, acquisition rate of multidrug-resistant organisms (MDROs), and nosocomial bacteremia rate. The choice of effect model was determined by heterogeneity.

Results

Our final analysis incorporated 12 studies involving 12,719 patients. Compared with multi-patient rooms in the ICU, single-patient rooms demonstrated a significant benefit in reducing the nosocomial infection rate (odds ratio [OR]: 0.68; 95% confidence interval [CI]: 0.59, 0.79; p < 0.00001). Analysis based on nosocomial infection incidence density revealed a statistically significant reduction in single-patient rooms (OR: 0.64; 95% CI: 0.44, 0.92; p = 0.02). Single-patient rooms were associated with a marked decrease in nosocomial colonization and infection rate (OR: 0.44; 95% CI: 0.32, 0.62; p < 0.00001). Furthermore, patients in single-patient rooms experienced lower nosocomial bacteremia rate (OR: 0.73; 95% CI: 0.59, 0.89; p = 0.002) and lower acquisition rate of MDROs (OR: 0.41; 95% CI: 0.23, 0.73; p = 0.002) than those in multi-patient rooms.

Conclusion

Implementation of single-patient rooms represents an effective strategy for reducing nosocomial infections in the ICU.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/).

Timing and clinical risk factors for early acquisition of gut pathogen colonization with multidrug resistant organisms in the intensive care unit

BACKGROUND

Microbiome restitution therapies are being developed to prevent gut pathogen colonization among patients in the intensive care unit (ICU) and in other select populations. If preventive therapies are to be effective, they must be administered prior to pathogen acquisition. The timing and risk factors for early acquisition of gut pathogen colonization (within 72 h) are currently unknown and could be helpful to guide ICU trial design.

METHODS

This was a prospective cohort study. Patients in the ICU had deep rectal swabs performed within 4 h of ICU admission and exactly 72 h later. Early gut pathogen colonization was classified as the new presence (based on culture of rectal swabs) of one or more of the following organisms of interest: methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant (VRE), and Gram-negative bacteria that showed multidrug resistance (MDR) or third generation Cephalosporin resistance (Ceph-R). Clinical risk factors for early acquisition of gut pathogen colonization were captured using the Acute Physiology and Chronic Health Evaluation IV (APACHE IV) scoring system.

FINDINGS

Among 131 patients who were swabbed at ICU admission and 72 h later, the rates of gut pathogen colonization at ICU admission were 11.4%, 10.6%, 38.6%, and 8.3% for MRSA, VRE, MDR and Ceph-R Gram-negatives respectively. Among the patients who were negative for a given pathogen at ICU admission, the rates of early acquisition of gut pathogen colonization were 7.8% for MRSA (95% CI 3.6 to 14.2%), 7.7% for VRE (95% CI 3.6 to 14.1%), 11.3% for MDR Gram-negatives (95% CI 4.4 to 18.8%), and 4.2% for Ceph-R Gram-negatives (95% CI 1.4 to 9.5%). There were no clinical risk factors which independently predicted early acquisition of gut pathogen colonization.

INTERPRETATION

Early gut pathogen colonization was common in the ICU, but our single-center study could not identify any clinical risk factors which were significantly associated with acquisition of gut pathogens.

[The structural and spatial design of German intensive care units from the point of view of infection control measures : Survey among ICU-KISS participants]

INTRODUCTION

Intensive care unit (ICU) structural and spatial design may play a role in infection prevention and control.

METHODS

Between 09/2021 and 11/2021 we performed an online survey among ICUs in Germany, Austria and Switzerland.

RESULTS

A total of 597 (40%) of the invited ICUs answered the survey; 20% of the ICUs were built before 1990. The median number of single rooms with interquartile range is 4 (IQR 2-6). The median total room number is 8 (IQR 6-12). The median room size is 19 (IQR 16-22) m2 for single rooms and 31 (26-37.5) m2 for multiple bed rooms. Furthermore, 80% of ICUs have sinks and 86.4% have heating, ventilation, air conditioning (HVAC) systems in patient rooms. 54.6% of ICUs must store materials outside of storage rooms due to lack of space and only 33.5% have a room dedicated to disinfection and cleaning of used medical devices. Comparing ICUs built before 1990 and after 2011 we could show a slightly increase of single rooms (3 [IQR 2-5] before 1990 vs. 5 [IQR 2-8] after 2011; p < 0.001).

DISCUSSION

A large proportion of German ICUs do not meet the requirements of German professional societies regarding the number of single rooms and size of the patient rooms. Many ICUs lack storage space and other functional rooms.

CONCLUSION

There is an urgent need to support the construction and renovation of intensive care units in Germany with adequate funding.

New Attempts to Inhibit Methicillin-Resistant Staphylococcus aureus Biofilm? A Combination of Daptomycin and Azithromycin

Objective

To investigate the antibacterial impact of daptomycin and azithromycin in vitro on methicillin-resistant Staphylococcus aureus (MRSA) biofilm.

Methods

(1) Measure the strain growth curve and the biofilm formation curve. (2) Determine the minimum inhibitory concentrations (MICs) of daptomycin and azithromycin. (3) Investigate the antibacterial impact of the combination of daptomycin and azithromycin. (4) Perform the evaluation of the intervention impact of antimicrobial agents on MRSA biofilm. (5) Observe the biofilm after intervention with the antibacterial agent.

Results

(1) MRSA exhibited three phases: lag phase (0-4 h), logarithmic growth (4-8 h) and stationary phase after 18 h; its biofilm began to form at 6 h, semi-matured at 24 h, and reached maturity after 48 h. (2) The MICs of daptomycin and azithromycin were 8 μg/mL and greater than 256 μg/mL, respectively. (3) The combination of daptomycin and azithromycin has an additive effect on MRSA (Fractional Inhibitory Concentration Index [FICI] 0.625) (FICI = MIC of drug A in combination/MIC of drug A alone + MIC of drug B in combination/MIC of drug B alone). Evaluation criteria: Synergistic effect is considered when FICI ≤ 0.5; additive effect is considered when 0.5 < FICI ≤ 1; irrelevant effect is considered when 1 < FICI ≤ 2; antagonistic effect is considered when FICI > 2). (4) Daptomycin or azithromycin at MICs inhibited not only the growth of planktonic bacteria but also the formation of biofilm. (5) The combination of both, in which group the ratio of live/dead bacteria is low and the biofilm morphology was incomplete, was more productive than monotherapy in against biofilm.

Conclusion

Both daptomycin and azithromycin have anti-MRSA biofilm activity, and daptomycin is dominant. The fact that the combination of both can significantly inhibit the further maturation of MRSA biofilm and destroy already formed biofilm demonstrates the superiority of the combination over the monotherapy.

Precision and Advanced Nano-Phytopharmaceuticals for Therapeutic Applications

Phytopharmaceuticals have been widely used globally since ancient times and acknowledged by healthcare professionals and patients for their superior therapeutic value and fewer side-effects compared to modern medicines. However, phytopharmaceuticals need a scientific and methodical approach to deliver their components and thereby improve patient compliance and treatment adherence. Dose reduction, improved bioavailability, receptor selective binding, and targeted delivery of phytopharmaceuticals can be likely achieved by molding them into specific nano-formulations. In recent decades, nanotechnology-based phytopharmaceuticals have emerged as potential therapeutic candidates for the treatment of various communicable and non-communicable diseases. Nanotechnology combined with phytopharmaceuticals broadens the therapeutic perspective and overcomes problems associated with plant medicine. The current review highlights the therapeutic application of various nano-phytopharmaceuticals in neurological, cardiovascular, pulmonary, and gastro-intestinal disorders. We conclude that nano-phytopharmaceuticals emerge as promising therapeutics for many pathological conditions with good compliance and higher acceptance.

Intensive Care Unit Built Environments: A Comprehensive Literature Review (2005-2020)

BACKGROUND

The intensive care environment in hospitals has been the subject of significant empirical and qualitative research in the 2005-2020 period. Particular attention has been devoted to the role of infection control, family engagement, staff performance, and the built environment ramifications of the recent COVID-19 global pandemic. A comprehensive review of this literature is reported summarizing recent advancements in this rapidly expanding body of knowledge.

PURPOSE AND AIM

This comprehensive review conceptually structures the recent medical intensive care literature to provide conceptual clarity and identify current priorities and future evidence-based research and design priorities.

METHOD AND RESULT

Each source reviewed was classified as one of the five types-opinion pieces/essays, cross-sectional empirical investigations, nonrandomized comparative investigations, randomized studies, and policy review essays-and into nine content categories: nature engagement and outdoor views; family accommodations; intensive care unit (ICU), neonatal ICU, and pediatric ICU spatial configuration and amenity; noise considerations; artificial and natural lighting; patient safety and infection control; portable critical care field hospitals and disaster mitigation facilities including COVID-19; ecological sustainability; and recent planning and design trends and prognostications.

CONCLUSIONS

Among the findings embodied in the 135 literature sources reviewed, single-bed ICU rooms have increasingly become the norm; family engagement in the ICU experience has increased; acknowledgment of the therapeutic role of staff amenities; exposure to nature, view, and natural daylight has increased; the importance of ecological sustainability; and pandemic concerns have increased significantly in the wake of the coronavirus pandemic. Discussion of the results of this comprehensive review includes topics noticeably overlooked or underinvestigated in the 2005-2020 period and priorities for future research.

Private patient rooms and hospital-acquired methicillin-resistant Staphylococcus aureus: A hospital-level analysis of administrative data from the United States

OBJECTIVE

To use hospital-level data from the US to determine whether private patient rooms (PPRs) are associated with fewer in hospital-acquired methicillin-resistant Staphylococcus aureus (HA-MRSA) infections.

METHODS

We retrospectively analyzed Texas Inpatient Public Use Data with discharges between September 2015 and August 2016 merged with American Hospital Association annual survey data. We used negative binomial regression to estimate the association between the proportion of PPRs within a hospital and the count of discharges with HA-MRSA infections, adjusting for potentially confounding variables.

RESULTS

We analyzed data for 340 hospitals and 2,670,855 discharges. HA-MRSA incidence within these hospitals was 386 per 100,000 discharges (95% CI: 379, 393) and, on average, 62.73% (95% CI: 58.99, 66.46) of rooms in these hospitals were PPRs. PPRs were significantly associated with fewer HA-MRSA infections (unadjusted IRR = 0.973, 95% CI: 0.968, 0.979; adjusted IRR = 0.992, 95% CI: 0.991, 0.994; p<0.001 for both); at the hospital level, as the percentage of PPRs increased, HA-MRSA infection rates decreased. This association was non-linear; in hospitals with few PPRs there was a stronger association between PPRs and HA-MRSA infection rate relative to hospitals with many PPRs.

CONCLUSION

We identified 0.8% fewer HA-MRSA infections for each 1% increase in PPRs as a proportion of all rooms, suggesting that private rooms provide substantial protection from HA-MRSA. Small changes may not induce significant improvements in HA-MRSA incidence, and hospitals seeking tangible benefits in HAI reduction likely need to markedly increase the proportion of PPRs through large-scale renovations. The effect of private rooms is disproportionate across hospitals. Hospitals with proportionately fewer PPRs stand to gain the most from adding additional PPRs, while those with an already high proportion of PPRs are unlikely to see large benefits. Our findings enable hospital administrators to consider potential patient safety benefits as they make decisions about facility design and renovation.

Effects of the proportion of high-risk patients and control strategies on the prevalence of methicillin-resistant Staphylococcus aureus in an intensive care unit

Background

The presence of nosocomial pathogens in many intensive care units poses a threat to patients and public health worldwide. Methicillin-resistant Staphylococcus aureus (MRSA) is an important pathogen endemic in many hospital settings. Patients who are colonized with MRSA may develop an infection that can complicate their prior illness.

Methods

A mathematical model to describe transmission dynamics of MRSA among high-risk and low-risk patients in an intensive care unit (ICU) via hands of health care workers is developed. We aim to explore the effects of the proportion of high-risk patients, the admission proportions of colonized and infected patients, the probability of developing an MRSA infection, and control strategies on MRSA prevalence among patients.

Results

The increasing proportion of colonized and infected patients at admission, along with the higher proportion of high-risk patients in an ICU, may significantly increase MRSA prevalence. In addition, the prevalence becomes higher if patients in the high-risk group are more likely to develop an MRSA infection. Our results also suggest that additional infection prevention and control measures targeting high-risk patients may considerably help reduce MRSA prevalence as compared to those targeting low-risk patients.

Conclusions

The proportion of high-risk patients and the proportion of colonized and infected patients in the high-risk group at admission may play an important role on MRSA prevalence. Control strategies targeting high-risk patients may help reduce MRSA prevalence.

Single-Room Ward Design and Its Impact on Service and Patient Outcomes: An Evaluation Study

BACKGROUND

Evidence suggests that single-room inpatient wards are associated with better patient outcomes than open-room wards but little is known about the impact on adverse events, patient satisfaction, and clinician experiences.

METHODS/PURPOSE

We evaluated the impact of a new inpatient single-room orthopaedic ward on patient and clinician outcomes using a medical record audit; patient, nurse, and medical doctor surveys; and nonparticipant observations in a tertiary hospital in Sydney, Australia.

RESULTS

The audit (1,569 patients; 819 open-room ward and 750 new single-room ward) revealed unchanged adverse event rates and fewer emergency calls after the move to a single-room ward. Survey responses from nurses, medical doctors, and patients were positive. Observations suggested that clinicians devised solutions to potential threats to patient safety.

CONCLUSION

The single-room ward design did not negatively impact on patient and clinician outcomes and was preferred by them. Clinicians organized their work to ensure patient safety.

Transmission pathways of multidrug-resistant organisms in the hospital setting: a scoping review

BACKGROUND

Prevalence of multidrug-resistant microorganisms (MDROs) continues to increase, while infection control gaps in healthcare settings facilitate their transmission between patients. In this setting, 5 distinct yet interlinked pathways are responsible for transmission. The complete transmission process is still not well understood. Designing and conducting a single research study capable of investigating all 5 complex and multifaceted pathways of hospital transmission would be costly and logistically burdensome. Therefore, this scoping review aims to synthesize the highest-quality published literature describing each of the 5 individual potential transmission pathways of MDROs in the healthcare setting and their overall contribution to patient-to-patient transmission.

METHODS

In 3 databases, we performed 2 separate systematic searches for original research published during the last decade. The first search focused on MDRO transmission via the HCW or the environment to identify publications studying 5 specific transmission pathways: (1) patient to HCW, (2) patient to environment, (3) HCW to patient, (4) environment to patient, and (5) environment to HCW. The second search focused on overall patient-to-patient transmission regardless of the transmission pathway. Both searches were limited to transmission of methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus, multidrug-resistant A. baumannii, and carbapenem-resistant Enterobacteriaceae. After abstract screening of 5,026 manuscripts, researchers independently reviewed and rated the remaining papers using objective predefined criteria to identify the highest quality and most influential manuscripts.

RESULTS

High-quality manuscripts were identified for all 5 routes of transmission. Findings from these studies were consistent for all pathways; however, results describing the routes from the environment/HCW to a noncolonized patient were more limited and variable. Additionally, most research focused on MRSA, instead of other MDROs. The second search yielded 10 manuscripts (8 cohort studies) that demonstrated the overall contribution of patient-to-patient transmission in hospitals regardless of the transmission route. For MRSA, the reported cross-transmission was as high as 40%.

CONCLUSIONS

This scoping review brings together evidence supporting all 5 possible transmission pathways and illustrates the complex nature of patient-to-patient transmission of MDROs in hospitals. Our findings also confirm that transmission of MDROs in hospitals occurs frequently, suggesting that ongoing efforts are necessary to strengthen infection prevention and control to prevent the spread of MDROs.

Prevalence and Microbiological Characteristics of qacA/B-Positive Methicillin-Resistant Staphylococcus aureus Isolates in a Surgical Intensive Care Unit

The increasing use of chlorhexidine for methicillin-resistant Staphylococcus aureus (MRSA) decolonization has raised concerns about the emergence of resistance to or tolerance of this antiseptic. We examined the frequency and characteristics of qacA/B chlorhexidine tolerance genes among MRSA isolates in a surgical intensive care unit (ICU) where MRSA-colonized patients are decolonized by chlorhexidine bathing. The MRSA isolates were evaluated for chlorhexidine susceptibility, mupirocin resistance, molecular typing, agr functionality, and the heterogeneous vancomycin-intermediate S. aureus (hVISA) phenotype according to the presence of the qacA/B genes. Overall, 119 MRSA isolates were obtained from active surveillance cultures (93, 78.2%) and clinical cultures (26, 21.8%) between 2012 and 2014. Among these isolates, 39 (32.8%) carried the qacA/B genes, and 23 (19.3%) exhibited mupirocin resistance. Most qacA/B-positive isolates (36/39, 92.3%) were identified as ST5-SCCmecII (69.2%) and ST239-SCCmecIII (23.1%), which are common healthcare-associated (HA)-MRSA strains in Korea. Multivariate analysis found that qacA/B-positive MRSA isolates were associated with agr dysfunction (OR, 4.87; 95% CI, 1.71-13.87) and the hVISA phenotype (OR, 4.09; 95% CI, 1.48-11.34). In conclusion, our study showed that qacA/B carriage was common among MRSA isolates in an ICU where chlorhexidine is commonly used for decolonization. qacA/B carriage was significantly associated with agr dysfunction and the hVISA phenotype. These features may confer a selective advantage on HA-MRSA strains, including ST5-SCCmecII and ST239-SCCmecIII, in the ICU setting.

The association between Staphylococcus aureus nasal colonization and symptomatic infection in children in Korea where ST72 is the major genotype: A prospective observational study

This study was performed to investigate the concordance in terms of molecular characteristics and antimicrobial susceptibility between colonizing and clinical Staphylococcus aureus isolates obtained from children in Korea, where ST72 is the major genotype.This was a prospective observational descriptive study of culture-confirmed S aureus infections obtained from children ≤18 years old admitted to Asan Medical Center Children's Hospital in Seoul, Korea, from March 2014 to April 2015. Molecular studies including multilocus sequence typing (MLST), SCCmec typing, polymerase chain reaction amplification of the Panton-Valentine leukocidin (PVL) genes, and antibiotic susceptibility tests were performed on S aureus isolates obtained from nares and clinical specimens.During the study period, 126 clinically significant S aureus infections were identified. Nasal swab cultures were made from 113 of the 126 children, and 46.0% (52/113) showed S aureus colonization. The overall concordance between colonizing and clinical isolates by methicillin susceptibility was 94.2% (49/52); all 3 discordant cases were HA-MSSA cases with nasal MRSA. Among the 37 pairs of colonizing and clinical S aureus isolates included in the genotyping analysis, ST72-SCCmec type IV was the most prevalent clone and the PVL genes were positive in 2 patients. Among the 31 pairs of healthcare-associated cases, concordance rates by methicillin susceptibility and sequence type (ST) were 90.3% (28/31) and 84% (26/31), respectively. For the 6 pairs of community-associated (CA) S aureus including 3 CA-MRSA cases, 100% concordance was observed by methicillin susceptibility and ST.The concordance between isolates obtained from children who required medical services was relatively high in Korean children where ST72-SCCmec type IV is the predominant clone as the colonizer and the pathogen. It is suggested that decolonization and continuous care to prevent transmission could be effective in managing and preventing both HA- and CA-SA infections in our setting.

Colonization pressure as a risk factor of ICU-acquired multidrug resistant bacteria: a prospective observational study

The primary objective of this study was to evaluate the impact of colonization pressure on intensive care unit (ICU)-acquired multidrug resistant bacteria (MDRB). All patients hospitalized for more than 48 h in the ICU were included in this prospective observational study. MDRB were defined as methicillin resistant Staphylococcus aureus, Pseudomonas aeruginosa resistant to ceftazidime or imipenem, Gram-negative bacilli producing extended-spectrum beta-lactamases (ESBL), and all strains of Acinetobacter baumannii and Stenotrophomonas maltophilia. Colonization pressure was daily calculated in the three participating ICUs. Univariate and multivariate analyses were used to determine risk factors for ICU-acquired MDRB. Two hundreds and four (34%) of the 593 included patients acquired an MDRB during their ICU stay. Multivariate analysis identified colonization pressure as an independent risk factor for ICU-acquired MDRB (OR (95% CI) 4.18 (1.03-17.01), p = 0.046). Other independent risk factors for ICU-acquired MDRB were mechanical ventilation (3.08 (1.28-7.38), p = 0.012), and arterial catheter use (OR, 3.04 (1.38-6.68), p = 0.006). ICU-acquired MDRB were associated with increased mortality, duration of mechanical ventilation, and ICU stay. However, ICU-acquired MDRB was not independently associated with ICU-mortality. Colonization pressure is an independent risk factor for acquiring MDRB in the ICU.

Transmission of Staphylococcus aureus between health-care workers, the environment, and patients in an intensive care unit: a longitudinal cohort study based on whole-genome sequencing

Background

Health-care workers have been implicated in nosocomial outbreaks of Staphylococcus aureus, but the dearth of evidence from non-outbreak situations means that routine health-care worker screening and S aureus eradication are controversial. We aimed to determine how often S aureus is transmitted from health-care workers or the environment to patients in an intensive care unit (ICU) and a high-dependency unit (HDU) where standard infection control measures were in place.

Methods

In this longitudinal cohort study, we systematically sampled health-care workers, the environment, and patients over 14 months at the ICU and HDU of the Royal Sussex County Hospital, Brighton, England. Nasal swabs were taken from health-care workers every 4 weeks, bed spaces were sampled monthly, and screening swabs were obtained from patients at admission to the ICU or HDU, weekly thereafter, and at discharge. Isolates were cultured and their whole genome sequenced, and we used the threshold of 40 single-nucleotide variants (SNVs) or fewer to define subtypes and infer recent transmission.

Findings

Between Oct 31, 2011, and Dec 23, 2012, we sampled 198 health-care workers, 40 environmental locations, and 1854 patients; 1819 isolates were sequenced. Median nasal carriage rate of S aureus in health-care workers at 4-weekly timepoints was 36·9% (IQR 35·7–37·3), and 115 (58%) health-care workers had S aureus detected at least once during the study. S aureus was identified in 8–50% of environmental samples. 605 genetically distinct subtypes were identified (median SNV difference 273, IQR 162–399) at a rate of 38 (IQR 34–42) per 4-weekly cycle. Only 25 instances of transmission to patients (seven from health-care workers, two from the environment, and 16 from other patients) were detected.

Interpretation

In the presence of standard infection control measures, health-care workers were infrequently sources of transmission to patients. S aureus epidemiology in the ICU and HDU is characterised by continuous ingress of distinct subtypes rather than transmission of genetically related strains.

Funding

UK Medical Research Council, Wellcome Trust, Biotechnology and Biological Sciences Research Council, UK National Institute for Health Research, and Public Health England.

ICU ward design and nosocomial infection rates: a cross-sectional study in Germany

BACKGROUND

There is increasing interest in the effects of hospital and ward design on multi-faceted infection control. Definitive evidence is rare and the state of knowledge about current ward design is lacking.

OBJECTIVE

To collect data on the current status of ward design for intensive care units (ICUs) and to analyse associations between particular design factors and nosocomial infection rates.

METHODS

In 2015, operational infrastructure data were collected via an online questionnaire from ICUs participating voluntarily in the German nosocomial infection surveillance system (KISS). A multi-variate analysis was subsequently undertaken with nosocomial infection rates from the KISS database from 2014 to 2015.

FINDINGS

In total, 534 ICUs submitted data about their operational infrastructure. Of these, 27.1% of beds were hosted in single-bed rooms with a median size of 18m² (interquartile range 15-21m²), and 73.5% of all ICU beds had a hand rub dispenser nearby. The authors were able to match 266 ICUs in the multi-variate analysis. ICUs with openable windows in patient rooms were associated with lower device-associated lower respiratory tract infections [odds ratio (OR) 0.73, 95% confidence interval (CI) 0.58-0.90]. ICUs with >40% two-bed rooms were associated with lower primary bloodstream infection rates (OR 0.66, 95% CI 0.51-0.86).

CONCLUSION

Only minor associations were found between design factors and ICU infection rates. Most were surrogates for other risk factors.

Tracing and inhibiting growth of Staphylococcus aureus in barbecue cheese production after product recall

Staphylococcal food poisoning is one of the most prevalent causes of foodborne intoxication worldwide. It is caused by ingestion of enterotoxins formed by Staphylococcus aureus during growth in the food matrix. Following a recall of barbecue cheese due to the detection of staphylococcal enterotoxins in Switzerland in July 2015, we analyzed the production process of the respective dairy. Although most cheese-making processes involve acidification to inhibit the growth of pathogenic bacteria, barbecue cheese has to maintain a pH >6.0 to prevent undesired melting of the cheese. In addition, the dairy decided to retain the traditional manual production process of the barbecue cheese. In this study, therefore, we aimed to (1) trace Staph. aureus along the barbecue cheese production process, and (2) develop a sustainable strategy to inhibit growth of Staph. aureus and decrease the risk of staphylococcal food poisoning without changing the traditional production process. To this end, we traced Staph. aureus in a step-wise blinded process analysis on 4 different production days using spa (Staphylococcus protein A gene) typing, DNA microarray profiling, and pulsed-field gel electrophoresis analysis. We subsequently selected a new starter culture and used a model cheese production including a challenge test assay to assess its antagonistic effect on Staph. aureus growth, as well as its sensory and technological implications. We detected Staph. aureus in 30% (37/124) of the collected samples taken from the barbecue cheese production at the dairy. This included detection of Staph. aureus in the final product on all 4 production days, either after enrichment or using quantitative detection. We traced 2 enterotoxigenic Staph. aureus strains (t073/CC45 and t282/CC45) colonizing the nasal cavity and the forearms of the cheesemakers to the final product. In the challenge test assay, we were able to show that the new starter culture inhibited growth of Staph. aureus while meeting the sensory and technological requirements of barbecue cheese production.

[Survey of methicillin-resistant Staphylococcus aureus control measures in hospitals participating in the VINCat program]

INTRODUCTION

VINCat is a nosocomial infection surveillance program in hospitals in Catalonia. The aim of the study was to determine the surveillance and control measures of methicillin-resistant Staphylococcus aureus (MRSA) in these centres.

METHODS

An e-mail survey was carried out from January to March 2013 with questions related to the characteristics of the hospitals and their control measures for MRSA.

RESULTS

A response was received from 53 hospitals (>500 beds: 7; 200-500 beds: 14;<200 beds: 32; had ICU: 29). Computer alert of readmissions was available in 63%. There was active surveillance of patients admitted from another hospital (46.2%) or a long-term-care centre (55.8%), both being significantly more common measures in hospitals with a rate of MRSA≤22% (global median). Compliance with hand hygiene was observed in 77.4% of the centres, and was greater than 50% in 69.7% of them. All hospitals had contact precautions, although 62.3% did not have exclusive frequently used clinical material in bedrooms. The room cleaning was performed more frequently in 54.7% of hospitals, and 67.9% of them had programs for the appropriate use of antibiotics.

CONCLUSIONS

This study provides information on the implementation of measures to prevent MRSA in hospitals participating in the VINCat program. Most of the centres have an MRSA protocol, however compliance with it should be improved, especially in areas such as active detection on admission in patients at risk, hand hygiene adherence, cleaning frequency and optimising the use of antibiotics.

Rapid, highly discriminatory binary genotyping to demonstrate methicillin-resistant Staphylococcus aureus transmission in a tertiary care intensive care unit

OBJECTIVES

No previous studies of methicillin-resistant Staphylococcus aureus (MRSA) epidemiology in adult intensive care units (ICUs) have assessed the utility of rapid, highly discriminatory strain typing in the investigation of transmission events.

DESIGN

Observational.

SETTING

A 22-bed medical-surgical adult ICU. Patients Those admissions MRSA-positive on initial screening and all admissions <48 hours in duration were excluded, leaving a cohort of 653 patients (median age, 61 years; APACHE-II, 19).

METHODS

We conducted this study of MRSA transmission over 1 year (August 1, 2011 to July 31, 2012) using a multiplex PCR-based reverse line blot (mPCR/RLB) assay to genotype isolates from surveillance swabs obtained at admission and twice weekly during ICU stays. MRSA prevalence and incidence rates were calculated and transmission events were identified using strain matching. Colonization pressure was calculated daily by summation of all MRSA cases.

RESULTS

Of 1,030 admissions to ICU during the study period, 349 patients were excluded. MRSA acquisition occurred during 31 of 681 (4.6%) remaining admissions; 19 of 31(61%) acquisitions were genotype-confirmed, including 7 (37%) due to the most commonly transmitted strain. Moving averages of MRSA patient numbers on the days prior to a documented event were used in a Poisson regression model. A significant association was found between transmission and colonization pressure when the average absolute colonization pressure on the previous day was ≥3 (χ2=7.41, P=0.01).

CONCLUSIONS

mPCR/RLB characterizes MRSA isolates within a clinically useful time frame for identification of single-source clusters within the ICU. High MRSA colonization pressure (≥3 MRSA-positive patients) on a given day is associated with an increased likelihood of a transmission event.

Whole-genome sequencing in hierarchy with pulsed-field gel electrophoresis: the utility of this approach to establish possible sources of MRSA cross-transmission

BACKGROUND

In order to study the micro-epidemiology of meticillin-resistant Staphylococcus aureus (MRSA) effectively, the molecular typing method used must be able to distinguish between different MRSA strains. Pulsed-field gel electrophoresis (PFGE) can detect small genetic differences but is limited in its potential to distinguish isolates within a major lineage. Whole-genome sequencing (WGS) provides sufficient resolution to support or exclude links between otherwise indistinguishable isolates, but lacks the practical utility of conventional typing methods.

AIM

To explore the utility of WGS in a hierarchical approach with PFGE to help establish possible sources of MRSA cross-transmission in the intensive care setting.

METHODS

Possible transmission routes from donor to recipient via the hands of staff, the air or environmental surfaces were identified. Focused molecular typing used PFGE to explore these transmission hypotheses. WGS was applied when an acquisition event involved a common PFGE pulsotype.

FINDINGS

Thirty-eight of the 78 acquisition events could not be explored as clinical isolates were not available. PFGE excluded all potential donors from 26 of the remaining 40 acquisition events, but did identify a probable source in 14 new colonizations. Within the hypotheses tested, PFGE supported links between patients occupying the same bay, the same bed space, adjacent isolation rooms and different wards. When a patient source was not identified, PFGE implicated the ward environment and the hands of staff. However, WGS disproved three of these transmission pathways.

CONCLUSION

WGS can complement conventional typing methods by confirming or refuting possible MRSA transmission hypotheses. Epidemiological data are crucial in this process.

The prevalence and significance of methicillin-resistant Staphylococcus aureus colonization at admission in the general ICU Setting: a meta-analysis of published studies

OBJECTIVE

To estimate the prevalence and significance of nasal methicillin-resistant Staphylococcus aureus colonization in the ICU and its predictive value for development of methicillin-resistant S. aureus infection.

DATA SOURCES

MEDLINE and EMBASE and reference lists of all eligible articles.

STUDY SELECTION

Studies providing raw data on nasal methicillin-resistant S. aureus colonization at ICU admission, published up to February 2013. Analyses were restricted in the general ICU setting. Medical, surgical, and interdisciplinary ICUs were eligible. ICU studies referring solely on highly specialized ICUs populations and reports on methicillin-resistant S. aureus outbreaks were excluded.

DATA EXTRACTION

Two authors independently assessed study eligibility and extrapolated data in a blinded fashion. The two outcomes of interest were the prevalence estimate of methicillin-resistant S. aureus nasal colonization at admission in the ICU and the sensitivity/specificity of colonization in predicting methicillin-resistant S. aureus-associated infections.

DATA SYNTHESIS

Meta-analysis, using a random-effect model, and meta-regression were performed. Pooled data extracted from 63,740 evaluable ICU patients provided an estimated prevalence of methicillin-resistant S. aureus nasal colonization at admission of 7.0% (95% CI, 5.8-8.3). Prevalence was higher for North American studies (8.9%; 95% CI, 7.1-10.7) and for patients screened using polymerase chain reaction (14.0%; 95% CI, 9.6-19). A significant per year increase in methicillin-resistant S. aureus colonization was also noted. In 17,738 evaluable patients, methicillin-resistant S. aureus infections (4.1%; 95% CI, 2.0-6.8) developed in 589 patients. The relative risk for colonized patients was 8.33 (95% CI, 3.61-19.20). Methicillin-resistant S. aureus nasal carriage had a high specificity (0.96; 95% CI, 0.90-0.98) but low sensitivity (0.32; 95% CI, 0.20-0.48) to predict methicillin-resistant S. aureus-associated infections, with corresponding positive and negative predictive values at 0.25 (95% CI, 0.11-0.39) and 0.97 (95% CI, 0.83-1.00), respectively.

CONCLUSIONS

Among ICU patients, 5.8-8.3% of patients are colonized by methicillin-resistant S. aureus at admission, with a significant upward trend. Methicillin-resistant S. aureus colonization is associated with a more than eight-fold increase in the risk of associated infections during ICU stay, and methicillin-resistant S. aureus infection develops in one fourth of patients who are colonized with methicillin-resistant S. aureus at admission to the ICU.

Whole-genome sequencing shows that patient-to-patient transmission rarely accounts for acquisition of Staphylococcus aureus in an intensive care unit

An assessment of Staphylococcus aureus acquisition among intensive care patients using serial sampling and whole-genome sequencing found less than a fifth of acquisitions resulted from patient-to-patient transmission. Whole-genome sequencing identified transmission more accurately than spa-typing and patient stay data.

Background. Strategies to prevent Staphylococcus aureus infection in hospitals focus on patient-to-patient transmission. We used whole-genome sequencing to investigate the role of colonized patients as the source of new S. aureus acquisitions, and the reliability of identifying patient-to-patient transmission using the conventional approach of spa typing and overlapping patient stay.

Methods. Over 14 months, all unselected patients admitted to an adult intensive care unit (ICU) were serially screened for S. aureus. All available isolates (n = 275) were spa typed and underwent whole-genome sequencing to investigate their relatedness at high resolution.

Results. Staphylococcus aureus was carried by 185 of 1109 patients sampled within 24 hours of ICU admission (16.7%); 59 (5.3%) patients carried methicillin-resistant S. aureus (MRSA). Forty-four S. aureus (22 MRSA) acquisitions while on ICU were detected. Isolates were available for genetic analysis from 37 acquisitions. Whole-genome sequencing indicated that 7 of these 37 (18.9%) were transmissions from other colonized patients. Conventional methods (spa typing combined with overlapping patient stay) falsely identified 3 patient-to-patient transmissions (all MRSA) and failed to detect 2 acquisitions and 4 transmissions (2 MRSA).

Conclusions. Only a minority of S. aureus acquisitions can be explained by patient-to-patient transmission. Whole-genome sequencing provides the resolution to disprove transmission events indicated by conventional methods and also to reveal otherwise unsuspected transmission events. Whole-genome sequencing should replace conventional methods for detection of nosocomial S. aureus transmission.

Relationship between nasal colonization and ventilator-associated pneumonia and the role of the environment in transmission of Staphylococcus aureus in intensive care units

BACKGROUND

This study assessed the relationship between nasal colonization and ventilator-associated pneumonia (VAP) by Staphylococcus aureus, as well the role of the environment in the transmission of this organism.

METHODS

We performed a cohort study of patients with VAP caused by methicillin-resistant S aureus (MRSA) or methicillin-sensitive S aureus during 2 years in an adult intensive care unit (ICU). All patients had nasal swab specimens obtained at admission and during the ICU stay. Clinical samples also were collected for analysis, as were samples from the hands of health care professionals and the environment, and were typed using pulsed-field gel electrophoresis.

RESULTS

S aureus VAP represented 12.5% of the cases, and statistical analysis identified colonization as a risk factor for the development of this infection. MRSA was isolated from the environment and hands, indicating the existence of a secondary reservoir. Molecular typing revealed a polyclonal profile; however, clone J was the most frequent (45.5%) among isolates of MRSA tested, with a greater profile of resistance than the other isolates. There was strong evidence suggesting transmission of MRSA to patients from the environment.

CONCLUSION

Nasal colonization for S aureus is a risk factor for development of VAP.

Relationships between the importation, transmission, and nosocomial infections of methicillin-resistant Staphylococcus aureus: an observational study of 112 Veterans Affairs Medical Centers

BACKGROUND

The study of hospital methicillin-resistant Staphylococcus aureus (MRSA) epidemiology is complicated by its transmissibility. Our objective was to understand how MRSA importation and transmission influence MRSA nosocomial infections in Veterans Affairs Medical Centers (VAMCs).

METHODS

We performed hospital-level analyses of acute-care MRSA admission prevalence, acquisition rates, and incident nosocomial clinical culture (INCC) rates, each a surrogate measure of importation, transmission, and nosocomial infection, respectively. We studied 112 VAMCs from October 2007 through September 2010, after the start of a bundled intervention including active surveillance for MRSA. We analyzed data using generalized linear mixed models.

RESULTS

A total of 2.9 million surveillance tests were collected from 1.4 million patient admissions. Overall MRSA admission prevalence was 11.4%, acquisition was 5.2 per 1000 patient-days at risk, and INCC was 1.8 per 1000 patient-days at risk. A 10% increase in a hospital's average admission prevalence was associated with a 9.7% increase in its weekly acquisition rates (P < .001) and a 9.8% increase in its weekly INCC rates (P < .001). Significant decreases were observed in all 3 measures during the study period (P < .001). When INCC rates were stratified by nasal MRSA carriage at admission, a significant downward trend was observed only among those initially negative.

CONCLUSIONS

Measured associations between MRSA admission prevalence, acquisition rate, and INCC rate were consistent with the hypothesis that decreased acquisition led to decreased importation, which in turn further abated acquisition. The downward trend in INCC rate specifically among individuals with negative admission surveillance tests suggests that decreasing transmission contributed to lower rates of nosocomial MRSA infection.

The Role of the Hospital Environment in the Prevention of Healthcare-Associated Infections by Contact Transmission

OBJECTIVE:

This article describes the role of the hospital environment in the spread of pathogens by direct and indirect contact. In addition, the prevention of transmission through interventions involving the built environment is discussed.

BACKGROUND:

The hospital environment can become contaminated with pathogenic microorganisms, some of which can persist for long periods of time. Although contamination is common, the contribution of the hospital environment to the development of healthcare-associated infections remains unclear. In part spurred by the development of newer technologies to enhance environmental cleaning or to prevent contamination, research into the role of the environment in causing healthcare-associated infections has accelerated.

TOPICAL HEADINGS:

A review of the recent literature finds an increasing body of evidence implicating contaminated surfaces in patient care areas in the transmission of pathogens and the development of infections. Single-patient rooms and optimally placed alcohol hand rub dispensers and other design features can mitigate infection risk. Enhanced environmental cleaning including touchless technologies and self-cleaning surfaces can reduce environmental contamination and may prevent infections.

CONCLUSIONS:

The hospital environment contributes to transmission of pathogens in hospitals and to the development of healthcare-associated infections. Newer technologies to prevent environmental contamination or to enhance cleaning are promising although additional studies with the endpoints of reduction of infections are needed before the role of these technologies is known.

Measurement and Impact of Staphylococcus aureus Colonization Pressure in Households

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) "colonization pressure" (CP) predicts infections in hospitals. We applied the CP concept to staphylococcal transmission within households. We tested the hypothesis that children with S aureus skin and soft tissue infection (SSTI) plus colonization ("cases") with higher baseline household CP (HHCP) would be at greater risk for persistent colonization and recurrent SSTI during study period.

METHODS

We collected baseline colonization swabs from 92 cases and 296 of their household contacts. Cases underwent decolonization. S aureus HHCP was calculated as the proportion of colonized household contacts at baseline (excluding cases). S aureus colonization and recurrent SSTI in cases were followed for 12 months.

RESULTS

Overall, median S aureus HHCP was 60% (mean = 55%). For cases colonized with MRSA, median MRSA HHCP was 11% (mean 29%); methicillin-susceptible S aureus (MSSA)-colonized cases had a median MSSA HHCP of 50% (mean = 49%). Over 1 year, MRSA HHCP was an independent risk factor for persistent MRSA colonization in cases (each 10-unit increase in HHCP associated with an adjusted odds ratio of 1.25; 95% confidence interval, 1.06-1.47). HHCP was not associated with recurrent SSTI in cases.

CONCLUSIONS

MRSA HHCP is associated with persistent colonization in outpatients. Further studies are needed to determine the relationship between persistent colonization of household contacts, environmental contamination, and SSTI.

The durability of examination gloves used on intensive care units

BACKGROUND

The use of examination gloves is part of the standard precautions to prevent medical staff from transmission of infectious agents between patients. Gloves also protect the staff from infectious agents originating from patients. Adequate protection, however, depends on intact gloves. The risk of perforation of examination gloves is thought to correlate with duration of wearing, yet, only very few prospective studies have been performed on this issue.

METHODS

A total number of 1500 consecutively used pairs of examination gloves of two different brands and materials (latex and nitrile) were collected over a period of two months on two ICU's. Used gloves were examined for micro perforations using the "water-proof-test" according to EN 455-1. Cox-regression for both glove types was used to estimate optimal changing intervals.

RESULTS

Only 26% of gloves were worn longer than 15 min. The total perforation rate was 10.3% with significant differences and deterioration of integrity of gloves between brands (p<0.001). Apart from the brand, "change of wound dressing" (p = 0.049) and "washing patients" (p = 0.001) were also significantly associated with an increased risk of perforation.

CONCLUSION

Medical gloves show marked differences in their durability that cannot be predicted based on the technical data routinely provided by the manufacturer. Based on the increase of micro perforations over time and the wearing behavior, recommendations for maximum wearing time of gloves should be given. Changing of gloves after 15 min could be a good compromise between feasibility and safety. HCWs should be aware of the benefits and limitations of medical gloves. To improve personal hygiene hand disinfection should be further encouraged.

The potential regional impact of contact precaution use in nursing homes to control methicillin-resistant Staphylococcus aureus

OBJECTIVE

Implementation of contact precautions in nursing homes to prevent methicillin-resistant Staphylococcus aureus (MRSA) transmission could cost time and effort and may have wide-ranging effects throughout multiple health facilities. Computational modeling could forecast the potential effects and guide policy making.

DESIGN

Our multihospital computational agent-based model, Regional Healthcare Ecosystem Analyst (RHEA).

SETTING

All hospitals and nursing homes in Orange County, California.

METHODS

Our simulation model compared the following 3 contact precaution strategies: (1) no contact precautions applied to any nursing home residents, (2) contact precautions applied to those with clinically apparent MRSA infections, and (3) contact precautions applied to all known MRSA carriers as determined by MRSA screening performed by hospitals.

RESULTS

Our model demonstrated that contact precautions for patients with clinically apparent MRSA infections in nursing homes resulted in a median 0.4% (range, 0%-1.6%) relative decrease in MRSA prevalence in nursing homes (with 50% adherence) but had no effect on hospital MRSA prevalence, even 5 years after initiation. Implementation of contact precautions (with 50% adherence) in nursing homes for all known MRSA carriers was associated with a median 14.2% (range, 2.1%-21.8%) relative decrease in MRSA prevalence in nursing homes and a 2.3% decrease (range, 0%-7.1%) in hospitals 1 year after implementation. Benefits accrued over time and increased with increasing compliance.

CONCLUSIONS

Our modeling study demonstrated the substantial benefits of extending contact precautions in nursing homes from just those residents with clinically apparent infection to all MRSA carriers, which suggests the benefits of hospitals and nursing homes sharing and coordinating information on MRSA surveillance and carriage status.

The epidemiology, treatment, and prevention of transmission of methicillin-resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) has been recognized as an important cause of health care-associated infections for several decades and has more recently emerged as a common cause of infection in persons without typical health care-associated risk factors. It is important for health care providers to have an understanding of the factors associated with MRSA acquisition and infection as well as the interventions that may reduce the risk of MRSA in health care and community settings.

Relationship between antibiotic consumption, oropharyngeal colonization, and ventilator-associated pneumonia by Staphylococcus aureus in an intensive care unit of a Brazilian teaching hospital

INTRODUCTION: his study evaluated the consumption of major classes of antibiotics, the colonization of the oropharynx of patients on mechanical ventilation, and the risk of ventilator-associated pneumonia (VAP) caused by Staphylococcus aureus in an intensive care unit for adults. METHODS: A case-control study was carried out using colonized patients (cases) by oxacillin-resistant S. aureus (ORSA) and (controls) oxacillin-sensitive S. aureus (OSSA) from May 2009 to August 2010. The occurrence of VAP by S. aureus was also evaluated in the same period. Antibiotic consumption was expressed as the number of defined daily doses (DDD)/1,000 patient-days for glycopeptides, carbapenems, and extended-spectrum cephalosporins. RESULTS: Three hundred forty-six (56.1%) patients underwent mechanical ventilation with a frequency of oropharyngeal colonization of 36.4%, corresponding to 63.5% for ORSA and 36.5% for OSSA. The risk of illness for this organism was significant (p<0.05), regardless of whether colonization/infection was by ORSA or OSSA. The consumption of antibiotics was high, mainly for broad-spectrum cephalosporins (551.26 DDDs/1,000 patient-days). The high density of use of glycopeptides (269.56 DDDs/1,000 patient-days) was related to colonization by ORSA (Pearson r=0.57/p=0.02). Additionally, age >60 years, previous antibiotic therapy, and previous use of carbapenems were statistically significant by multivariate analysis. CONCLUSIONS: There was a significant relationship between the colonization of the oropharyngeal mucosa and the risk of VAP by both phenotypes. The use of glycopeptides was related to colonization by ORSA.

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.

Impact of screening and identifying methicillin-resistant Staphylococcus aureus carriers on hand hygiene compliance in 4 intensive care units

BACKGROUND

Our objective was to assess the impact of screening and identifying methicillin-resistant Staphylococcus aureus (MRSA) carriers as a single measure in 4 intensive care units (ICUs).

METHODS

An evaluative study including two 6-month periods was conducted prospectively. The evaluation concerned the hand hygiene compliance (HHC) for contacts with MRSA carriers versus contacts with noncarriers (comparison C1, main objective) and for a period of absence of identification (P1) versus a period of identification (P2) (comparison C2) and MRSA cross transmission (P1 vs P2) (comparison C3) measured with 2 indicators.

RESULTS

Overall, 1326 opportunities of hand hygiene were observed. Concerning C1, the HHC for contacts with MRSA carriers was 42.5% versus 43.1% for contacts with noncarriers (not significant). This absence of difference was recorded whatever the ICU specialty, the category of personnel, and the nature of contacts. Concerning C2, the HHC in P1 was 44.8% versus 48.5% in P2 (not significant). Concerning C3, no significant difference was identified between the 2 periods.

CONCLUSION

We did not identify any advantage by using screening and identifying MRSA carriers in those 4 ICUs in which no specific strategy of additional contact measures was implemented for MRSA carriers.

Systematic review of measurement and adjustment for colonization pressure in studies of methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, and clostridium difficile acquisition

OBJECTIVE

Colonization pressure is an important infection control metric. The aim of this study was to describe the definition and measurement of and adjustment for colonization pressure in nosocomial-acquisition risk factor studies of methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), and Clostridium difficile.

METHODS

We performed a computerized search of studies of nosocomial MRSA, VRE, and C. difficile acquisition published before July 1, 2009, through MEDLINE. Studies were included if a study outcome was MRSA, VRE, or C. difficile acquisition; the authors identified risk factors associated with MRSA, VRE, or C. difficile acquisition; and the study measured colonization pressure.

RESULTS

The initial MEDLINE search yielded 505 articles. Sixty-six of these were identified as studies of nosocomial MRSA, VRE, or C. difficile acquisition; of these, 18 (27%) measured colonization pressure and were included in the final review. The definition of colonization pressure varied considerably between studies: the proportion of MRSA- or VRE-positive patients (5 studies), the proportion of MRSA- or VRE-positive patient-days (6 studies), or the total or mean number of MRSA-, VRE-, or C. difficile-positive patients or patient-days (7 studies) in the unit over periods of varying length. In 10 of 13 studies, colonization pressure was independently associated with MRSA, VRE, or C. difficile acquisition.

CONCLUSION

There is a need for a simple and consistent method to quantify colonization pressure in both research and routine clinical care to accurately assess the effect of colonization pressure on cross-transmission of antibiotic-resistant bacteria.

MRSA prevalence in European healthcare settings: a review

BACKGROUND

During the past two decades, methicillin-resistant Staphylococcus aureus (MRSA) has become increasingly common as a source of nosocomial infections. Most studies of MRSA surveillance were performed during outbreaks, so that results are not applicable to settings in which MRSA is endemic. This paper gives an overview of MRSA prevalence in hospitals and other healthcare institutions in non-outbreak situations in Western Europe.

METHODS

A keyword search was conducted in the Medline database (2000 through June 2010). Titles and abstracts were screened to identify studies on MRSA prevalence in patients in non-outbreak situations in European healthcare facilities. Each study was assessed using seven quality criteria (outcome definition, time unit, target population, participants, observer bias, screening procedure, swabbing sites) and categorized as 'good', 'fair', or 'poor'.

RESULTS

31 observational studies were included in the review. Four of the studies were of good quality. Surveillance screening of MRSA was performed in long-term care (11 studies) and acute care (20 studies). Prevalence rates varied over a wide range, from less than 1% to greater than 20%. Prevalence in the acute care and long-term care settings was comparable. The prevalence of MRSA was expressed in various ways - the percentage of MRSA among patients (range between 1% and 24%), the percentage of MRSA among S. aureus isolates (range between 5% and 54%), and as the prevalence density (range between 0.4 and 4 MRSA cases per 1,000 patient days). The screening policy differed with respect to time points (on admission or during hospital stay), selection criteria (all admissions or patients at high risk for MRSA) and anatomical sampling sites.

CONCLUSIONS

This review underlines the methodological differences between studies of MRSA surveillance. For comparisons between different healthcare settings, surveillance methods and outcome calculations should be standardized.

Colonization and transmission of meticillin-susceptible and meticillin-resistant Staphylococcus aureus in a murine nasal colonization model

Nasal colonization by Staphylococcus aureus is an important risk factor for the development of a nosocomial infection. Acquisition of nasal colonization by S. aureus increases mortality in hospitalized patients, but little is known about the transmission dynamics of S. aureus. To study S. aureus transmission, colonization and colonization persistence, we developed a murine transmission model. In 20 cages, 2 out of 10 mice were nasally inoculated (at 5×10(8) c.f.u. per mouse) with either meticillin-susceptible S. aureus (MSSA) (10 cages) or meticillin-resistant S. aureus (MRSA) (10 cages). On days 5, 15, 25 and 40, all mice in a cage were swabbed or sacrificed and nasal colonization and c.f.u. were determined in all 10 mice by nasal dissection or by nasal swab. Spread and subsequent stable colonization by both MSSA and MRSA from colonized to uncolonized mice within a cage was seen. At day 5, an increased number of colonized mice were observed in the MSSA group compared to the MRSA group (P = 0.003). On day 40, the mean number of c.f.u. per mouse was higher for MRSA than for MSSA (P = 0.06). Faecal-oral transmission was shown to be a possibly important transmission route in this model. These results suggest a more rapid spread of MSSA compared to MRSA. However, MRSA shows a more stable nasal colonization after a longer period of time.

Methicillin-resistant staphylococcus aureus screening and eradication in the surgical intensive care unit: Is it worth it?

BACKGROUND

The problem of intensive care unit methicillin-resistant Staphylococcus aureus (MRSA) infections has led to routine surveillance and eradication strategies.

METHODS

Our surgical intensive care unit (SICU) admissions receive MRSA nares cultures and if positive are isolated followed by eradication treatment. This strategy was retrospectively reviewed.

RESULTS

Our nares-positive culture rate was 21% (30/145), and the sputum positive (sputum+) rate was 18% (26/145). Positive nares culture (Nares+) was eradicated in 63%. The rate of sputum+ in Nares+ patients was 36% (9/25). The rate of sputum+ in Nares- was 10% (12/115; P = .003). The sputum+ SICU length of stay (LOS) (18 ± 12 days in 23 S+ patients) is longer than in sputum- (10 ± 9 days in 69 S-patients, P = .0002).

CONCLUSIONS

This SICU has high rates of both nares and sputum MRSA cultures. Our data suggest eradicating nares colonization may prevent pneumonia and might decrease SICU LOS.

MRSA in a large German University Hospital: Male gender is a significant risk factor for MRSA acquisition

BACKGROUND

The continually rising number of hospital acquired infections and particularly MRSA (Methicillin-resistant Staphylococcus aureus) colonization poses a major challenge from both clinical and epidemiological perspectives. The assessment of risk factors is vital in determining the best prevention, diagnosis and treatment strategies.

MATERIALS AND METHODS

We analyzed 798 cases of MRSA in a large German University Hospital over a 7-year period. Data was collected retro- and prospectively including patient age, sex, type of ward and duration of inpatient stay. In addition we analyzed all cases on ICU with regards to cross infection and MRSA genotyping via DNA MicroArray Technology. The years 2004 to 2007 were analyzed with a specific focus on gender.

RESULTS

Male gender is significantly correlated with increased risk of MRSA acquisition (p<0.001), the predominant setting for MRSA is on ICU. 75% of the MRSA positive patients are over 50 years of age (average age 59.8 years). The inpatient time was 4.15 times higher in MRSA carriers compared with non-MRSA cases, however this was not significant. MRSA genotyping on ICU showed mainly the subtypes ST 5, ST 22, ST 228, however cross contamination with identical genotypes was only detected in a minority of cases (5 out of 22).

CONCLUSION

Unlike previous studies which show no or inconclusive evidence of gender as a risk factor, our data confirm that male gender is a significant risk factor for MRSA carrier status. Further research will be required to investigate the aetiology of these findings.

Current views of health care design and construction: practical implications for safer, cleaner environments

Infection preventionists (IP) play an increasingly important role in preventing health care-associated infection in the physical environment associated with new construction or renovation of health care facilities. The Guidelines for Design and Construction of Hospital and Healthcare Facilities, 2010, formerly known as "AIA Guidelines" was the origin of the "infection control risk assessment" now required by multiple agencies. These Guidelines represent minimum US health care standards and provide guidance on best practices. They recognize that the built environment has a profound affect on health and the natural environment and require that health care facilities be designed to "first, do no harm." This review uses the Guidelines as a blueprint for IPs' role in design and construction, updating familiar concepts to the 2010 edition with special emphasis on IP input into design given its longer range impact on health care-associated infection prevention while linking to safety and sustainability. Section I provides an overview of disease transmission risks from the built environment and related costs, section II presents a broad view of design and master planning, and section III addresses the detailed design strategies for infection prevention specifically addressed in the 2010 Facility Guidelines Institute edition.

Management of antibiotic resistance in the intensive care unit setting

Over the past few decades, an alarming increase of infections caused by antibiotic-resistant pathogens, including methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus species, carbapenem-resistant Pseudomonas aeruginosa, extended-spectrum beta-lactamase-producing Escherichia coli and Klebsiella spp., and multidrug-resistant Acinetobacter spp., has been observed, particularly in intensive care units. For clinicians, the rising resistance rate observed in nosocomial pathogens, when coupled with the lack of effective antimicrobials, represents the real challenge in the therapeutic management of critically ill patients. The contribution of clinicians in minimizing the increasing trend of resistance is represented by reduction of the patients' exposure to antibiotics, which reduces the resistance-selecting pressure, and by avoiding unnecessary antibiotic treatments. Recent issues on strategies to minimize resistance development and to appropriately manage critically ill patients with infections caused by multidrug-resistant organisms in the intensive care unit setting are discussed in this article.