Previous Methicillin-resistant Staphylococcus Aureus Infection Research Articles

Methicillin-resistant Staphylococcus aureus colonization among healthcare workers in Oman.

Methicillin-Resistant Staphylococcus aureus (MRSA) is a S. aureus strain characterized by resistance to cloxacillin. Healthcare workers (HCWs), are recognized for their heightened risk for MRSA acquisition and possibly for MRSA nosocomial transmission. This cross-sectional study aimed to determine the prevalence and the associated risk factors of MRSA colonization among healthcare workers at Sultan Qaboos University Hospital (SQUH) in Oman. A total of 200 nasal swab samples were collected from the healthcare workers at SQUH during the period October 2nd 2018 to January 7th 2019. All nasal swab samples were examined microbiologically for the presence of MRSA using the standard method and the results were confirmed by detection of the mecA product (PBP2a). Data on associated risk factors for MRSA colonization was collected and analyzed. Forty-one of the 200 screened healthcare workers (20.5%) were found to have nasal carriage of Staphylococcus aureus of which 63.4% were Methicillin Sensitive and 36.6% were Methicillin-Resistant (MRSA). Methicillin-Resistant Staphylococcus aureus (MRSA) was isolated from fifteen of the 200 screened healthcare workers giving a prevalence rate of nasal colonization with MRSA of 7.5%. We found no statistical association between healthcare worker MRSA nasal colonization and age, gender, HCWs specialty, hand hygiene practices, skin condition, previous MRSA infection, and previous exposure to antibiotics. Identification of the prevalence and the associated risk factors of MRSA colonization in healthcare workers mandates continuous surveillance and the implementation of all possible preventive measures to reduce re-occurrences.

Prediction of methicillin-resistant Staphylococcus aureus bloodstream infection: do we need rapid diagnostic tests?

Staphylococcus aureus (SA) is the leading cause of bloodstream infection (BSI). The incidence of methicillin-resistant SA (MRSA) has decreased in France and Europe since one decade. Early and precise prediction of methicillin susceptibility is needed to improve probabilistic antibiotic therapy of MRSA-BSI. The aim of this study was to identify MRSA-BSI risk factors at admission and evaluate which patients need costly rapid diagnostic tests. A single-center retrospective descriptive study of all diagnosed SA-BSI was conducted in a French University Hospital between January 2015 and December 2016. All medical charts were reviewed. Univariate and multivariate analyses by a logistic regression model were performed on the data. We then build a prediction score of MRSA-BSI by assigning one point for each of the risk factor identified. During the study period, 151 SA-BSI were identified including 32 (21%) MRSA-BSI. In multivariate analysis, three factors were associated with MRSA-BSI: coming from long-term care facility, known previous MRSA colonization and/or infection, and chronic renal disease. Among our population, respectively, 5% and 100% had a MRSA-BSI when no or three risk factors were identified. Therefore, among the PCR performed, 43 (96%) could be avoided according to our clinical score. In our study, methicillin-susceptible SA and MRSA-BSI can be predictable by counting MRSA risk factors. This prediction rule could avoid the use of expensive rapid diagnostic tests. Prospective studies and prediction rules could help physicians to predict SA-BSI susceptibility to improve appropriate empiric therapy choice.

Length of stay and odds of MRSA acquisition: a dose-response relationship?

The association between methicillin-resistant Staphylococcus aureus (MRSA) colonisation and/or infection with increased morbidity and mortality among hospital patients has long been recognised. We sought to build on previous studies to identify modifiable risk factors associated with the acquisition of MRSA colonisation and infection by conducting a retrospective cohort study on patients admitted through the Emergency Department of an acute tertiary-care general hospital in Singapore which implemented universal on-admission MRSA screening. Patients were assigned to the acquisition or non-acquisition group depending on whether they acquired MRSA during their admission. We used logistic regression models with a patient being in the acquisition group as the binary outcome to identify factors associated with MRSA acquisition. A total of 1302 acquisition and 37 949 non-acquisition group patients were analysed. Fifteen variables were included in the multivariate model. A dose-response relationship between length of stay and odds of MRSA acquisition was observed, with a length of stay 3 weeks or more (Adj OR 11.78-57.36, all P < 0.001) being the single biggest predictor of MRSA acquisition. Other variables significantly associated with MRSA acquisition were: male gender, age 65 or greater, previous MRSA colonisation or infection, exposure to certain antibiotics and surgery, and history of diabetes.

Burden of Invasive Methicillin-Resistant Staphylococcus aureus Infections in Nursing Home Residents.

To describe the epidemiology and incidence of invasive methicillin-resistant Staphylococcus aureus (MRSA) infections in nursing home (NH) residents, which has previously not been well characterized. Retrospective analysis of public health surveillance data. Healthcare facilities in 33 U.S. counties. Residents of the surveillance area. Counts of NH-onset and hospital-onset (HO) invasive MRSA infections (cultured from sterile body sites) identified from the Centers for Disease Control and Prevention Emerging Infections Program (EIP) population-based surveillance from 2009 to 2013 were compared. Demographic characteristics and risk factors of NH-onset cases were analyzed. Using NH resident-day denominators from the Centers for Medicare and Medicaid Services Skilled Nursing Facility Cost Reports, incidence of NH-onset invasive MRSA infections from facilities in the EIP area was determined. A total of 4,607 NH-onset and 4,344 HO invasive MRSA cases were reported. Of NH-onset cases, median age was 74, most infections were bloodstream infections, and known risk factors for infection were common: 1,455 (32%) had previous MRSA infection or colonization, 1,014 (22%) had decubitus ulcers, 1,098 (24%) had recent central venous catheters, and 1,103 (24%) were undergoing chronic dialysis; 2,499 (54%) had been discharged from a hospital in the previous 100 days. The in-hospital case-fatality rate was 19%. The 2013 pooled mean incidence of NH-onset invasive MRSA infections in the surveillance area was 2.4 per 100,000 patient-days. More NH-onset than HO cases occurred, primarily in individuals with known MRSA risk factors. These data reinforce the importance of infection prevention practices during wound and device care in NH residents, especially those with a history of MRSA infection or colonization.

Risk Factors for Methicillin-Resistant Staphylococcus aureus (MRSA) Colonization Among Patients Admitted to Obstetrical Units: A Nested Case-Control Study.

Methicillin-resistant Staphylococcus aureus (MRSA) among obstetrical patients can increase birth complications for both mothers and infants, but little is known about the risk factors for MRSA in this population. The objective of this study was to determine the prevalence of MRSA among obstetrical patients and identify risk factors associated with MRSA colonization. This nested case-control study used obstetrical patients with MRSA colonization identified through a universal screening program at The Ottawa Hospital (February 2008-January 2010). Cases and three matched controls were compared using chi-square tests for categorical variables, median and interquartile range (IQR), and Wilcoxon rank-sum tests for continuous variables. Conditional logistic regression using ORs and 95% CIs was used to identify risk factors. Standard microbiologic techniques and pulsed-field gel electrophoresis of the MRSA isolates from case patients were performed. Out of 11 478 obstetrical patients, 39 (0.34%) were MRSA colonized; 117 patients were selected as matched controls. The median age was 30 (IQR 27.5-35.00) and median length of stay was 2.55 days (IQR 1.95-3.24). Only MRSA cases had a previous MRSA infection (4 vs. 0). MRSA cases had significantly higher parity (median 3; IQR 2-5) compared with controls (median 2; IQR 1-3) (OR 1.52; 95% CI 1.22-1.90) CONCLUSION: This study identified a low prevalence of MRSA among obstetrical patients. Risk factors associated with MRSA colonization were previous MRSA infection and multiparity. Obstetrical patients who previously tested positive for MRSA should be placed on contact precautions at the time of hospital admission because this is a risk factor for future colonization.

Empiric Methicillin Resistant Staphylococcus aureus Coverage in the Early Ventilator Associated Pneumonia Window: If and When

Choice of empiric antibiotic(s) for early ventilator associated pneumonia (VAP) involves weighing the risks of potential infection with multi-drug resistant (MDR) pathogens against those of over-exposure to broad-spectrum agents. Although early VAP is believed to be rarely caused by MDR pathogens, the overall incidence of all methicillin resistant Staphylococcus aureus (MRSA) infections is increasing. We questioned if MRSA VAP is becoming more common and if these infections were occurring earlier in the patient's hospital course. We hypothesized that 1) early (2-4 d from intubation) VAP caused by MRSA is relatively uncommon and 2) those patients with early VAP because of MRSA had risk factors associated with a MDR organism infection. Bronchoscopies with lavage (BALs) from patients admitted to our SICU from 2010-2013 were reviewed. MRSA VAP was defined as growth of ≥10(5) cfu/mL from BAL. Multi-drug resistant risk factors included a previous MRSA infection or positive nasal swab, antibiotic use within 90 d, hospitalization for >5 d, hemodialysis, homelessness, intravenous drug use, and men having sex with men. In the 3-y period, there were 438 cases of VAP. Forty-seven specimens from 43 patients had quantitative microbiologic confirmation of MRSA VAP for an overall prevalence of 10.7%. Of patients with early VAP, three of 106 (2.8%) were MRSA positive. Culture results were graphed according to ventilator days ( Fig. 1 ). The median days ventilated at the time of MRSA VAP were 8 d (range 2-81). All of the early MRSA VAP patients had identifiable risk factors for MRSA infection. The negative predictive value for patients not having a risk factor was one. These data suggest that the incidence of MRSA VAP is stable. Those patients with early MRSA VAP demonstrated traditional MDR risk factors. Patients without risk factors in the early time period could effectively be ruled out from having MRSA VAP and likely do not require empiric MRSA coverage.

Risk Factors of Methicillin-Resistant Staphylococcus aureus Infection and Correlation With Nasal Colonization Based on Molecular Genotyping in Medical Intensive Care Units: A Prospective Observational Study.

Methicillin-resistant Staphylococcus aureus (MRSA) is a common and important cause of colonization and infection in medical intensive care units (ICU). The aim of this study was to assess association factors between MRSA nasal colonization and subsequent infections in medical ICU patients by clinical investigation and molecular genotyping.A prospective cohort observational analysis of consecutive patients admitted to medical ICUs between November 2008 and May 2010 at a tertiary teaching hospital were included. To detect MRSA colonization, the specimens from the nares were obtained within 3 days of admission to the ICU and again 1 week following admission to the ICU. Genetic relatedness for colonized and clinical isolates from each study patient with MRSA infection were analyzed and compared.A total of 1266 patients were enrolled after excluding 195 patients with already present MRSA infections. Subsequent MRSA infection rates were higher in patients with nasal colonization than in those without (39.1% versus 14.7%, respectively). Multivariate Poisson regression analysis demonstrated that nasal MRSA colonization (relative risk [RR]: 2.50; 95% confidence interval [CI]: 1.90–3.27; P < 0.001) was independent predictors for subsequent MRSA infections. History of tracheostomy, however, was a protective predictor in all patients (RR: 0.38; 95% CI: 0.18–0.79; P = 0.010) and in patients with MRSA nasal colonization (RR: 0.22; 95% CI: 0.55–0.91; P = 0.037). Molecular genetics studies revealed that most MRSA isolates were healthcare-associated clones and that nasal and clinical isolates exhibited up to 75% shared identity.Methicillin-resistant S. aureus nasal colonization was significantly associated with subsequent MRSA infection among medical ICU patients. Previous MRSA infection was associated with subsequent MRSA infections, and history of tracheostomy associated with reducing this risk. Most MRSA isolates were healthcare-associated strains that were significantly correlated between nasal and clinical isolates.

Methicillin-resistant Staphylococcus aureus: decolonization and prevention prescribing practices for children treated with skin abscesses/boils in a pediatric emergency department.

This study aimed to describe methicillin-resistant Staphylococcus aureus (MRSA) eradication/prevention practices of clinicians managing patients with skin and soft tissue infections (SSTIs), specifically, in those patients undergoing abscess incision and drainage (I&D) in a pediatric emergency department (ED). A retrospective cohort study was performed for children aged 0 to 18 years old undergoing I&D of cutaneous abscess between January 1, 2011, and December 31, 2011, in the Cincinnati Children's Hospital Medical Center ED. Five hundred seventy-five patients underwent abscess I&D during our study period. Approximately 25% of our population had previous history of MRSA, SSTI, or boil/abscess; in addition, 26% of our population had a household family member with a previous history of MRSA, SSTI, or boil/abscess. Wound cultures were obtained in 399 (69%) of 575 of I&D abscesses, and of these, 57% of the I&D abscesses grew MRSA. Of all patients, only 3.7% (21 patients) had documentation of MRSA eradication/prevention instructions for patient/family. Methicillin-resistant S aureus eradication/prevention discussions are not commonly included in discharge instructions for patients undergoing abscess I&D. Given the significant proportion with previous MRSA infection, the ED may be a setting to provide instructions to patients/families with recurrent infections.

Progression from new methicillin-resistant Staphylococcus aureus colonisation to infection: an observational study in a hospital cohort

BackgroundPatients newly colonised with methicillin-resistant Staphylococcus aureus (MRSA) are at higher risk of clinical MRSA infection. At present, there are limited data on the duration or magnitude of this risk in a hospital population with a known time of MRSA acquisition.MethodsA retrospective cohort study of 909 adult patients known to have newly identified MRSA colonisation during admission to National University Hospital, Singapore between 1 July 2007 and 30 June 2011 was undertaken. Patients were excluded if they had history of previous MRSA colonisation or infection, or if they had been a hospital inpatient in the preceding 12 months. Data were collected on the development of MRSA infection requiring hospitalisation up to 30 June 2012.ResultsOf 840 patients newly colonised with MRSA as identified on active surveillance and not clinical specimens, 546 were men (65.0%) and the median age was 65 years (range 18–103 years). Median follow up was 24 months (range 0 –64 months, 85.1% followed >6 months). Clinical infection occurred in 121 patients (14.4%) with median time to infection of 22 days (95% CI 14–31). Overall 71.9% (87/121) of infected patients developed infection within 60 days of the date MRSA colonisation was detected. However, 17/121 patients (14.0%) developed clinical infection more than six months after documented MRSA acquisition. The most common sites of clinical infection were skin and soft tissue (49/121, 40.5%, 95% CI 31.7-49.8), respiratory tract (37/121, 30.6%, 95% CI 22.5-39.6) and bone and joint infections (14/121, 11.6%, 95% CI 6.5-18.7). Thirteen patients (13/121, 10.7%, 95% CI 5.8-17.7) had bacteraemias, of which six (5.0% 95% CI 1.8-10.5) were primary and seven (5.7%, 95% CI 2.3-11.6) were secondary to infection at other sites. Crude mortality at 30 days and six months was higher in patients with MRSA infection than colonisation alone (aOR 5.49, 95% CI 2.75-10.95, p<0.001 and aOR 2.94, 95% CI 1.78-4.85, p<0.001 respectively).ConclusionRisk of clinical infection is highest soon after MRSA acquisition. Prevention of MRSA acquisition in hospital will have significant impact on morbidity and mortality for patients.

Assessment of the Influence of Test Characteristics on the Clinical and Cost Impacts of Methicillin-ResistantStaphylococcus aureusScreening Programs in US Hospitals

To compare the impacts of different methicillin-resistant Staphylococcus aureus (MRSA) screening test options (eg, polymerase chain reaction [PCR], rapid culture) and program characteristics on the clinical outcomes and budget of a typical US hospital. We developed an Excel-based decision-analytic model, using published literature to calculate and compare hospital costs and MRSA infection rates for PCR- or culture-based MRSA screening and then used multivariate sensitivity analysis to evaluate key variables. Same-day PCR testing for a representative 370-bed teaching hospital in the United States was assessed in different populations (high-risk patients, intensive care unit [ICU] patients, or all patients) and compared with other test options. Different screening program populations (all patients, high-risk patients, ICU patients, or patients with previous MRSA colonization or infection only) represented a potential savings of $12,158-$76,624 per month over no program ($188,618). Analysis of multiple test options in high-risk population screening indicated that same-day PCR testing of high-risk patients resulted in fewer infections over 1,720 patient-days (2.9, compared with 3.5 for culture on selective media and 3.8 for culture on nonselective media) and the lowest total cost ($112,012). The costs of other testing approaches ranged from $113,742 to $123,065. Sensitivity analysis revealed that variations in transmission rate, conversion to infection, prevalence increases, and hospital size are important to determine program impact. Among test characteristics, turnaround time is highly influential. All screening options showed reductions in infection rates and cost impact improvement over no screening program. Among the options, same-day PCR testing for high-risk patients slightly edges out the others in terms of fewest infections and greatest potential cost savings.

Prevalence of and risk factors for methicillin-resistant Staphylococcus aureus skin and soft tissue infection in a Canadian emergency department

We sought to estimate the period prevalence of methicillin-resistant Staphylococcus aureus (MRSA) skin and soft tissue infection (SSTI) and evaluate risk factors for MRSA SSTI in an emergency department (ED) population. We carried out a cohort study with a nested case-control design. Patients presenting to our ED with a wound culture and a discharge diagnosis of SSTI between January 2003 and September 2004 were dichotomized as MRSA positive or negative. Fifty patients with MRSA SSTI matched by calendar time to 100 controls with MRSA-negative SSTI had risk factors assessed using multivariate conditional logistic regression. Period prevalence of MRSA SSTI was 54.8% (95% confidence interval [CI] 50.2%-59.4%). The monthly period prevalence increased from 21% in January 2003 to 68% in September 2004 (p < 0.01). Risk factors for MRSA SSTI were injection drug use (IDU) (odds ratio [OR] 4.6, 95% CI 1.4-16.1), previous MRSA infection and colonization (OR 6.4, 95% CI 2.1-19.8), antibiotics in 8 weeks preceding index visit (OR 2.6, 95% CI 1.2-8.1), diabetes mellitus (OR 4.1, 95% CI 1.4-12.1), abscess (OR 5.6, 95% CI 1.8-17.1) and admission to hospital in previous 12 months (OR 2.6, 95% CI 1.1-11.2). The period prevalence of MRSA SSTI between January 2003 and September 2004 was 54.8% at our institution. There was a marked increase in the monthly period prevalence from the beginning to the end of the study. Risk factors are IDU, previous MRSA infection and colonization, prescriptions for antibiotics in previous 8 weeks and admission to hospital in the preceding 12 months. On the basis of local prevalence and risk factor patterns, emergency physicians should consider MRSA as a causative agent for SSTI.

Methicillin-resistant Staphylococcus aureus bacteraemia diagnosed at hospital admission: distinguishing between community-acquired versus healthcare-associated strains

Methicillin-resistant Staphylococcus aureus (MRSA) infections diagnosed at hospital admission are often referred to as community-acquired. This designation may include MRSA strains previously acquired in a healthcare setting (healthcare-associated) as well as those that have emerged from community-based S. aureus strains. To understand further the epidemiology of MRSA from the community, a case-control study was performed. During 1997-2002, 254 patients with and without MRSA bacteraemia at hospital admission were studied. All patients with MRSA bacteraemia in the first 24 h of hospital admission had a recent exposure to a healthcare setting: true community-acquired MRSA was not detected. Independent risk factors for healthcare-associated MRSA bacteraemia, defined as MRSA bacteraemia in the first 24 h of hospital admission among patients with a recent exposure to a healthcare setting or intervention, included previous MRSA infection or colonization (OR = 17, P < 0.001), cellulitis (OR = 4, P = 0.006), presence of a central venous catheter (OR = 3, P < 0.001) and skin ulcers (OR = 3, P = 0.007). In this study, MRSA bacteraemia diagnosed in the first 24 h of hospital admission represented healthcare-associated MRSA strains and not true community-acquired strains. The clinical characteristics associated with healthcare-associated MRSA bacteraemia can assist clinicians in targeting measures to prevent cross-transmission and may help to streamline empirical vancomycin therapy.