Methicillin-resistant Staphylococcus Aureus Transmission Research Articles

Prevalence of MRSA colonization in Japanese neonatal care unit patients in 2011

The neonatal intensive care unit (NICU) is a high-risk setting for transmission of methicillin-resistant Staphylococcus aureus (MRSA). The recent prevalence of colonization with MRSA in patients and its control measures are unknown in Japanese NICU. We investigated the prevalence of MRSA colonization in patients and measures to control and prevent health-care-associated transmission in Japanese NICU in 2011. A nationwide survey was performed in facilities certified as training hospitals for neonatologists. Data in NICU and growing care units (GCU) were collected and analyzed regarding surveillance cultures for MRSA and the proportion of MRSA-colonized patients in September 2011. Trends in the proportion of MRSA-colonized patients and the measures to control and prevent health-care-associated MRSA transmission were investigated in the surveyed NICU in 2000, 2003, and 2011. A total of 168 NICU and 158 GCU were analyzed. The proportions of NICU and GCU that conducted regular surveillance cultures for MRSA were 81% and 66%, respectively. MRSA colonization was not found in 53% of NICU and in 45% of GCU. The percentage of NICU reported to be free of MRSA colonization increased over time. Use of alcohol-based hand rub and gloves by clinical staff and cohorting for identified MRSA-positive patients became more common in 2011 than in 2000 or 2003. Approximately half of Japanese NICU did not observe any patients with MRSA colonization in September 2011. Control and prevention measures have changed to use of alcohol-based hand rub and gloves in the last decade.

A case study of a real-time evaluation of the risk of disease transmission associated with a failure to follow recommended sterilization procedures

BackgroundFailures to follow recommendations for reprocessing of surgical instruments may place patients at risk for exposure to pathogenic microorganisms. When such failures occur, medical facilities often face considerable uncertainty and challenges in assessing the actual risks of disease transmission.MethodsIn 2011, staff at an Ohio hospital determined that surgical instruments inside a Steriset Container had inadvertently been autoclaved on a gravity cycle rather than on the recommended pre-vacuum cycle, potentially exposing 72 patients who underwent surgery with the instruments to risk of infection. To provide an assessment of the level of risk, we tested the effectiveness of the machine washer/disinfector step and of the sterilization process inside the Steriset Container on the gravity cycle for killing of Geobacillus stearothermophilus spores, Clostridium difficile spores, and methicillin-resistant Staphylococcus aureus (MRSA). Based on the test results, the risk of transmission of MRSA by the instruments was calculated and the risk of transmission of hepatitis B virus was estimated.ResultsThe machine washer/disinfector consistently reduced MRSA recovery by a factor of 1:100,000. The sterilization process inside the Steriset Container consistently reduced MRSA concentrations by a factor of >1:10,000,000 and killed 105C. difficile spores and 105G. stearothermophilus spores. The risk of MRSA transmission due to the incident was calculated to be 1 in 100 trillion.ConclusionsThe risk for transmission of infection due to the failure to follow recommended sterilization processes was negligible based upon complete killing of G. stearothermophilus biological indicator spores, C. difficile spores, and MRSA under conditions that replicated the incident where proper procedures were not followed. Such real-time assessments of the risks associated with specific incidents may provide evidence-based information that can be used to inform decisions regarding disclosure of the incident to patients.

Teasing Out the Transmission of MRSA

Controversy persists about the best interventions to reduce hospital-acquired methicillin-resistant Staphylococcus aureus (MRSA) infections. In a previous quasi-experimental study conducted at Department of Veterans Affairs (VA) medical centers, a bundle involving active surveillance, contact precautions, hand hygiene, and institutional culture change was associated with a decrease in healthcare-associated MRSA infections. On the other hand, a cluster-randomized study involving adult intensive care …

Knowledge, perceptions, and practices of methicillin-resistant Staphylococcus aureus transmission prevention among health care workers in acute-care settings

Health care workers (HCWs) play a critical role in prevention of health care-associated infections such as methicillin-resistant Staphylococcus aureus (MRSA), but glove and gown contact precautions and hand hygiene may not be consistently used with vulnerable patients. A cross-sectional survey of MRSA knowledge, attitudes/perceptions, and practices among 276 medical, nursing, allied health, and support services staff at an acute-care hospital in the eastern United States was completed in 2012. Additionally, blinded observations of hand hygiene behaviors of 104 HCWs were conducted. HCWs strongly agreed that preventive behaviors reduce the spread of MRSA. The vast majority reported that they almost always engage in preventive practices, but observations of hand hygiene found lower rates of adherence among nearly all HCW groups. HCWs who reported greater comfort with telling others to take action to prevent MRSA transmission were significantly more likely to self-report adherence to recommended practices. It is important to reduce barriers to adherence with preventive behaviors and to help all HCWs, including support staff who do not have direct patient care responsibilities, to translate knowledge about MRSA transmission prevention methods into consistent adherence of themselves and their coworkers to prevention guidelines.

Mitigation and Education

Mitigation and Education

Effectiveness of Hospital-Wide Methicillin-Resistant Staphylococcus aureus (MRSA) Infection Control Policies Differs by Ward Specialty

Methicillin-resistant Staphylococcus aureus (MRSA) is a major cause of preventable nosocomial infections and is endemic in hospitals worldwide. The effectiveness of infection control policies varies significantly across hospital settings. The impact of the hospital context towards the rate of nosocomial MRSA infections and the success of infection control is understudied. We conducted a modelling study to evaluate several infection control policies in surgical, intensive care, and medical ward specialties, each with distinct ward conditions and policies, of a tertiary public hospital in Sydney, Australia. We reconfirm hand hygiene as the most successful policy and find it to be necessary for the success of other policies. Active screening for MRSA, patient isolation in single-bed rooms, and additional staffing were found to be less effective. Across these ward specialties, MRSA transmission risk varied by 13% and reductions in the prevalence and nosocomial incidence rate of MRSA due to infection control policies varied by up to 45%. Different levels of infection control were required to reduce and control nosocomial MRSA infections for each ward specialty. Infection control policies and policy targets should be specific for the ward and context of the hospital. The model we developed is generic and can be calibrated to represent different ward settings and pathogens transmitted between patients indirectly through health care workers. This can aid the timely and cost effective design of synergistic and context specific infection control policies.

Relationships Between the Importation, Transmission, and Nosocomial Infections of Methicillin-Resistant Staphylococcus aureus: An Observational Study of 112 Veterans Affairs Medical Centers

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). 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. 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. 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.

Admission Screening of Methicillin-Resistant Staphylococcus aureus with Rapid Molecular Detection in Intensive Care Unit: A Three-Year Single-Centre Experience in Hong Kong

Background. The admission screening of methicillin-resistant Staphylococcus aureus (MRSA) by rapid molecular assay is considered to be an effective method in reducing the transmission of MRSA in intensive care unit (ICU). Method. The admission screening on patients from ICU once on their admissions by BD GeneOhm MRSA assay has been introduced to Prince of Wales Hospital, Hong Kong, since 2008. The assay was performed on weekdays and reported on the day of testing. Patients pending for results were under standard precautions until the negative screening results were notified, while contact precautions were implemented for MRSA-positive patients. In this study, we compared the MRSA transmission rate in molecular screening periods (2008 to 2010) with the historical culture periods (2006 to 2007) as control. Results. A total of 4679 samples were tested; the average carriage rate of MRSA on admission was 4.45%. By comparing with the historical culture periods, the mean incidence ICU-acquired MRSA infection was reduced from 3.67 to 1.73 per 1000 patient bed days. Conclusion. The implementation of admission screening of MRSA with molecular method in intensive care unit could reduce the MRSA transmission, especially in the area with high MRSA prevalence situation in Hong Kong.

Preventing the transmission of methicillin-resistant Staphylococcus aureus at a tertiary care cancer center in Japan: Quality improvement report

Although methicillin-resistant Staphylococcus aureus (MRSA) is endemic in the majority of Japanese hospitals, national guidelines for the control and prevention of MRSA continue to be lacking. Also, the metrics to survey the incidence of MRSA transmission in health care facilities is not standardized. We improved MRSA control practices referring to the 2003 Society for Healthcare Epidemiology of America guidelines and assessed the effect of multifaceted interventions by quasiexperimental analysis at a tertiary hospital in Japan.

Diversity of Methicillin-Resistant Staphylococcus aureus Strains Isolated from Residents of 26 Nursing Homes in Orange County, California

Nursing homes represent a unique and important methicillin-resistant Staphylococcus aureus (MRSA) reservoir. Not only are strains imported from hospitals and the community, strains can be transported back into these settings from nursing homes. Since MRSA bacteria are prevalent in nursing homes and yet relatively poorly studied in this setting, a multicenter, regional assessment of the frequency and diversity of MRSA in the nursing home reservoir was carried out and compared to that of the MRSA from hospitals in the same region. The prospective study collected MRSA from nasal swabbing of residents of 26 nursing homes in Orange County, California, and characterized each isolate by spa typing. A total of 837 MRSA isolates were collected from the nursing homes. Estimates of admission prevalence and point prevalence of MRSA were 16% and 26%, respectively. The spa type genetic diversity was heterogeneous between nursing homes and significantly higher overall (77%) than the diversity in Orange County hospitals (72%). MRSA burden in nursing homes appears largely due to importation from hospitals. As seen in Orange County hospitals, USA300 (sequence type 8 [ST8]/t008), USA100 (ST5/t002), and a USA100 variant (ST5/t242) were the dominant MRSA clones in Orange County nursing homes, representing 83% of all isolates, although the USA100 variant was predominant in nursing homes, whereas USA300 was predominant in hospitals. Control strategies tailored to the complex problem of MRSA transmission and infection in nursing homes are needed in order to minimize the impact of this unique reservoir on the overall regional MRSA burden.

First Outbreak with MRSA in a Danish Neonatal Intensive Care Unit: Risk Factors and Control Procedures

IntroductionThe purpose of the study was to describe demographic and clinical characteristics and outbreak handling of a large methicillin-resistant Staphylococcus aureus (MRSA) outbreak in a neonatal intensive care unit (NICU) in Denmark June 25th–August 8th 2008, and to identify risk factors for MRSA transmission.MethodsData were collected retrospectively from medical records and the Danish Neobase database. All MRSA isolates obtained from neonates, relatives and NICU health care workers (HCW) as well as environmental cultures were typed.ResultsDuring the 46 day outbreak period, 102 neonates were admitted to the two neonatal wards. Ninety-nine neonates were subsequently sampled, and 32 neonates (32%) from 25 families were colonized with MRSA (spa-type t127, SCCmec V, PVL negative). Thirteen family members from 11 of those families (44%) and two of 161 HCWs (1%) were colonized with the same MRSA. No one was infected. Five environmental cultures were MRSA positive. In a multiple logistic regression analysis, nasal Continuous Positive Airway Pressure (nCPAP) treatment (p = 0.006) and Caesarean section (p = 0.016) were independent risk factors for MRSA acquisition, whereas days of exposure to MRSA was a risk factors in the unadjusted analysis (p = 0.04).ConclusionsMRSA transmission occurs with high frequency in the NICU during hospitalization with unidentified MRSA neonates. Caesarean section and nCPAP treatment were identified as risk factors for MRSA colonization. The MRSA outbreak was controlled through infection control procedures.

Transmission and Persistence of Methicillin-ResistantStaphylococcus aureusin Milk, Environment, and Workers in Dairy Cattle Farms

The aim of this study was to determine the presence and persistence of methicillin-resistant Staphylococcus aureus (MRSA) in milk, farm environment, and farmers on 22 dairy cattle farms in Korea during 2008-2009. Genetic relatedness among the MRSA isolates was also investigated. Of 1146 samples examined, 35 of 559 (6.3%) quarter milk samples from 371 cows, four of 86 (4.7%) hand and nose samples from 43 farmers, and 6 of 501 (1.2%) farm environment samples were MRSA positive. Except for three isolates, all MRSA were classified into ST72-spa t324-SCCmec IV with PVL negative, the most predominant clonal type among community-associated MRSA in South Korea. All 35 MRSA-positive milk samples from 19 cows were obtained from a single farm (Farm G) out of 22 (4.5%) farms tested. The farm G was revisited 1 year later and milk samples were collected for examination of MRSA again. Two of six previous MRSA-positive cattle that had been kept on the farm still harbored MRSA genetically identical to MRSA strains, which were isolated from the same farm a year ago. The results of this study provide the evidence of transmission of MRSA among cattle, farm environment, and farmers and also long-term persistence of MRSA in animals.

P054: Prevalence and risk factor analysis for methicillin-resistant Staphylococcus aureus colonization in an acute care hospital

Methicillin-resistant Staphylococcus aureus (MRSA) infections have been associated with increased mortality and hospital costs. Active surveillance cultures (ASCs) for MRSA and aggressive contact precautions have been shown to reduce MRSA transmission. Universal screening incurs financial and physical resources.

Methicillin‐resistant Staphylococcus aureus: an issue for veterinary hospitals

To investigate the spread of methicillin-resistant Staphylococcus aureus (MRSA) isolated from a cluster of clinical cases at a veterinary hospital by molecular epidemiological techniques. Antimicrobial susceptibility testing, spa typing, multilocus sequence typing and pulsed-field gel electrophoresis were used to compare 16 isolates of MRSA. Four isolates were cultured from clinical cases thought to be involved in the cluster. A single isolate that was unrelated to the cluster and the remaining 10 isolates were obtained from nasal swabs submitted by staff and students during a subsequent survey of MRSA carriage. Isolates from four clinical cases and an isolate obtained from a staff member were the same strain of MRSA. Some key risk factors associated with transmission of MRSA within veterinary hospitals were identified. The information provided by these techniques was invaluable in developing procedures and identifying risk factors to help reduce the effect of future outbreaks within veterinary hospitals.

Methicillin Resistant Staphylococcus aureus Transmission in the Inpatient Psychiatric Hospital Setting

Surveillance data and the Infection Risk Assessment indicate incidence of Methicillin Resistant Staphylococcus aureus (MRSA) occurrence exceeds incidence of other multi drug resistant organisms (MDRO) in our hospital posing the highest risk for infection. The primary objective of the study: to identify the actual MRSA transmission rate on the patient care unit with the highest known pressure for transmission.

Molecular Epidemiology of Community-Associated Methicillin-resistant Staphylococcus aureus in the genomic era: a Cross-Sectional Study

Methicillin-resistant Staphylococcus aureus (MRSA) is a leading cause of healthcare-associated infections and significant contributor to healthcare cost. Community-associated-MRSA (CA-MRSA) strains have now invaded healthcare settings. A convenience sample of 97 clinical MRSA isolates was obtained from seven hospitals during a one-week period in 2010. We employed a framework integrating Staphylococcus protein A typing and full-genome next-generation sequencing. Single nucleotide polymorphisms were analyzed using phylodynamics. Twenty-six t002, 48 t008, and 23 other strains were identified. Phylodynamic analysis of 30 t008 strains showed ongoing exponential growth of the effective population size the basic reproductive number (R0) ranging from 1.24 to 1.34. No evidence of hospital clusters was identified. The lack of phylogeographic clustering suggests that community introduction is a major contributor to emergence of CA-MRSA strains within hospitals. Phylodynamic analysis provides a powerful framework to investigate MRSA transmission between the community and hospitals, an understanding of which is essential for control.

Comparison of control strategies for methicillin-resistant Staphylococcus aureus

Screening patients for methicillin-resistant Staphylococcus aureus (MRSA) colonization and contact precautions for colonized patients has been recommended when other control measures have been ineffective. We compared MRSA transmission rates following implementation of a bundle of control measures that included institutional culture change, surveillance for MRSA infection and transmission, and active screening for colonization in 2 similar Veterans Health Administration hospitals. One hospital employed contact precautions as defined by the Centers for Disease Control and Prevention, and the other hospital modified contact precautions, requiring only the use of gloves. During the 4-year study period, there were 1.58 MRSA transmissions per 1,000 patient-days at hospital A and 1.56 MRSA transmissions per 1,000 patient-days at hospital B (P = .98). Both hospitals experienced significant reductions in MRSA health care-associated infections (HAI). There was no difference between hospital A and hospital B in incidence of MRSA HAIs or MRSA surgical site infections. Annual acquisition costs for cover gowns were $183,609 at hospital A and $25,812 at hospital B. Significant reductions in MRSA HAI were associated with implementation of the MRSA control bundle. The bundle that included full contact precautions for colonized patients was no more effective in prevention of MRSA transmissions than a similar bundle that omitted the use of cover gowns.

Transmission of methicillin-resistant staphylococcus aureus in the long term care facilities in Hong Kong

BackgroundThe relative contribution of long term care facilities (LTCFs) and hospitals in the transmission of methicillin-resistant Staphylococcus aureus (MRSA) is unknown.MethodsConcurrent MRSA screening and spa type analysis was performed in LTCFs and their network hospitals to estimate the rate of MRSA acquisition among residents during their stay in LTCFs and hospitals, by colonization pressure and MRSA transmission calculations.ResultsIn 40 LTCFs, 436 (21.6%) of 2020 residents were identified as ‘MRSA-positive’. The incidence of MRSA transmission per 1000-colonization-days among the residents during their stay in LTCFs and hospitals were 309 and 113 respectively, while the colonization pressure in LTCFs and hospitals were 210 and 185 per 1000-patient-days respectively. MRSA spa type t1081 was the most commonly isolated linage in both LTCF residents (76/121, 62.8%) and hospitalized patients (51/87, 58.6%), while type t4677 was significantly associated with LTCF residents (24/121, 19.8%) compared with hospitalized patients (3/87, 3.4%) (p < 0.001). This suggested continuous transmission of MRSA t4677 among LTCF residents. Also, an inverse linear relationship between MRSA prevalence in LTCFs and the average living area per LTCF resident was observed (Pearson correlation −0.443, p = 0.004), with the odds of patients acquiring MRSA reduced by a factor of 0.90 for each 10 square feet increase in living area.ConclusionsOur data suggest that MRSA transmission was more serious in LTCFs than in hospitals. Infection control should be focused on LTCFs in order to reduce the burden of MRSA carriers in healthcare settings.

Estimating the Effectiveness of Isolation and Decolonization Measures in Reducing Transmission of Methicillin-resistant Staphylococcus aureus in Hospital General Wards

Infection control for hospital pathogens such as methicillin-resistant Staphylococcus aureus (MRSA) often takes the form of a package of interventions, including the use of patient isolation and decolonization treatment. Such interventions, though widely used, have generated controversy because of their significant resource implications and the lack of robust evidence with regard to their effectiveness at reducing transmission. The aim of this study was to estimate the effectiveness of isolation and decolonization measures in reducing MRSA transmission in hospital general wards. Prospectively collected MRSA surveillance data from 10 general wards at Guy's and St. Thomas' hospitals, London, United Kingdom, in 2006–2007 were used, comprising 14,035 patient episodes. Data were analyzed with a Markov chain Monte Carlo algorithm to model transmission dynamics. The combined effect of isolation and decolonization was estimated to reduce transmission by 64% (95% confidence interval: 37, 79). Undetected MRSA-positive patients were estimated to be the source of 75% (95% confidence interval: 67, 86) of total transmission events. Isolation measures combined with decolonization treatment were strongly associated with a reduction in MRSA transmission in hospital general wards. These findings provide support for active methods of MRSA control, but further research is needed to determine the relative importance of isolation and decolonization in preventing transmission.

Prevalence of Methicillin Resistant Staphylococcus aureus Nasal Carriage and its Antibiogram in Healthcare Workers from South of Jordan

Background: Healthcare workers (HCWs) can act as asymptomatic carrier in transmitting Methicillin Resistant Staphylococcus aureus (MRSA). Availability of epidemiological and antibiotic susceptibility data is necessary to limit the spread of HCWs-associated MRSA infections, and to help physicians in choosing the appropriate empirical antibiotic for management of such infections. Objective: to assess nasal carriage and antibiogram of MRSA in healthcare workers from Southern Jordan. Methods: a total of 276 nasal swabs were randomly collected from the HCWs. MRSA was identified by culture, biochemical and molecular methods. Antibiotic susceptibility was determined by the disc diffusion method. Results: The HCWs-MRSA nasal carriage was 8.7%. There was significant difference for nasal carriage of MRSA by nurse occupation (p value = 0.007), education level of less than a university degree (p value = 0.039) and years of HCW experience (p value = 0.023). No significant difference by age, sex, antibiotic exposure or smoking. Antibiotic resistance to Trimethoprim-Sulfamethoxazole and Tetracycline was detected in 37.5% and 12.5% of all MRSA isolates respectively. No resistance to the other antibiotics used in this study and no multidrug resistance was encountered in all MRSA isolates. Conclusion: MRSA nasal carriage among HCWs in this study was 8.7% with no alarming antibiotic resistance pattern. Nurses, less educated and more experienced HCWs are at increased risk of MRSA nasal carriage. Therefore, we strongly recommend screening and decolonizing positive HCWs who can act as asymptomatic carriers in MRSA transmission cycle. Keywords: Methicillin resistant Staphylococcus aureus, Healthcare workers, Antibiogram