Meticillin-resistant Staphylococcus Aureus Colonization Research Articles

Prevalence and factors associated with methicillin-resistant Staphylococcus aureus colonization on admission to geriatric care units: impact on screening practices

Universal screening for methicillin-resistant Staphylococcus aureus (MRSA) entails additional costs, and there is no consensus for targeted screening for high-risk units. The aims of this study were to determine the prevalence of MRSA in geriatric care units, and to identify the factors associated with MRSA colonization on admission. This retrospective case-control study (1:1) in the geriatric care unit of six Belgian hospitals covered the period from 1st January 2021 to 31st December 2022. Cases were patients with a positive MRSA screening result within 48h of admission to the geriatric care unit, and controls were patients with a negative screening result. In total, 556 patients were included in this study (278 in each group). Prevalence per 100 admissions for the total sample was 2.3 [95% confidence interval (CI) 2.2-2.6]. Significant multi-variate factors associated with MRSA carriage on admission were: history of MRSA, nursing home origin, and chronic skin lesions. Applying these three factors would give an area under the receiver operating characteristic (ROC) curve of 0.73 (95% CI 0.71-0.77), and would allow screening to be carried out in only 55.4% of cases (95% CI 51.2-59.6%). Using these factors as screening criteria in geriatric care units could significantly reduce the number of patients screened for MRSA, while maintaining satisfactory sensitivity and specificity.

Cost-effectiveness of a real-time spatiotemporal mapping surveillance system for meticillin-resistant Staphylococcus aureus prevention

An infection surveillance system based on a hospital's digital twin [4D-Disease Outbreak Surveillance System (4D-DOSS)] is being developed in Singapore. It offers near-real-time infection surveillance and mapping capabilities. This early economic modelling study was conducted, using meticillin-resistant Staphylococcus aureus (MRSA) as the pathogen of interest, to assess the potential cost-effectiveness of 4D-DOSS. A Markov model that simulates the likelihood of MRSA colonization and infection was developed to evaluate the cost-effectiveness of adopting 4D-DOSS for MRSA surveillance from the hospital perspective, compared with current practice. The cycle duration was 1 day, and the model horizon was 30 days. Probabilistic sensitivity analysis was conducted, and the probability of cost-effectiveness was reported. Scenario analyses and a value of information analysis were performed. In the base-case scenario, with 10-year implementation/maintenance costs of 4D-DOSS of $0, there was 68.6% chance that 4D-DOSS would be cost-effective. In a more pessimistic but plausible scenario where the effectiveness of 4D-DOSS in reducing MRSA transmission was one-quarter of the base-case scenario with 10-year implementation/maintenance costs of $1 million, there was 47.7% chance that adoption of 4D-DOSS would be cost-effective. The value of information analysis showed that uncertainty in MRSA costs made the greatest contribution to model uncertainty. This early-stage modelling study revealed the circumstances for which 4D-DOSS is likely to be cost-effective at the current willingness-to-pay threshold, and identified the parameters for which further research will be worthwhile to reduce model uncertainty. Inclusion of other drug-resistant organisms will provide a more thorough assessment of the cost-effectiveness of 4D-DOSS.

Impact of control measures including decolonization and hand hygiene for orthopaedic surgical site infection caused by MRSA at a Japanese tertiary-care hospital

Meticillin-resistant Staphylococcus aureus (MRSA) is the most common pathogen in orthopaedic surgical site infections (SSIs). However, few studies have investigated the transmission process of orthopaedic MRSA SSI. To investigate the transmission process of orthopaedic MRSA SSI using epidemiological and molecular analyses and to determine a method to prevent MRSA SSI innosocomial orthopaedic surgery. Active MRSA surveillance, preoperative decolonization and contact precautions for MRSA-positive cases was performed at our institution. Changes in epidemic strains were evaluated and the possibility of transmission from patients in an orthopaedic ward of a Japanese tertiary-care hospital was assessed by genotyping stored MRSA strains. In addition, data on the prevalence of MRSA SSI, MRSA colonization, and use of an alcohol antiseptic agent (mL/patient-days) during 2005-2022 were retrospectively assessed. SCCmec type II strain in the SSI group decreased over time, associated with fewer outbreaks. Even during a period of high infection rates, no cases of transmission-induced SSI from nasal MRSA carriers were identified. The infection rate correlated negatively with the use of an alcohol antiseptic agent (r = -0.82; P < 0.0001). Two cases among five nasal carriers developed MRSA SSI caused by strains different from those related to nasal colonization. The infection control measures for transmission from the hospital reservoirs including strict adherence to hand hygiene and decolonization of carriers is likely to be important for the prevention of orthopaedic MRSA SSI. However, the need for contact precautions for decolonized nasal carriers might be low.

Colonization of Extended-spectrum β-lactamase producing Enterobacterales and meticillin-resistant S. aureus in the intensive care unit at a tertiary hospital in Tanzania: Implications for Infection control and prevention

SummaryBackgroundMulti-drug resistant (MDR) bacteria pose a major global threat to public-health and are of particular concern to hospitalized intensive care unit (ICU) patients. This study aimed at addressing the burden of MDR and the associated factors at admission to ICU.MethodsThis was a cross-sectional study conducted at the ICU of a tertiary hospital in Tanzania. Rectal and anterior nares swabs were collected within 48 hours of ICU admission to screen for extended-spectrum beta-lactamase-producing Enterobacterales (ESBL-PE) and meticillin-resistant Staphylococcus aureus (MRSA), respectively.ResultsThe proportion of fecal carriage for ESBL-PE at admission to ICU was 54.54% (95% CI, 47.52–61.39), and nasal carriage for MRSA was 9.32% (95%CI, 5.67–14.93). The nasal MRSA colonization (OR = 1.52) and fecal carriage for ESBL-PE (OR=1.38) were more likely in participants who had received antibiotics before ICU admission than not, but association was not statistically significant. Hospitalization for ≥2 days (OR=1.18) was associated with fecal carriage of ESBL-PE, though not statistically significant. Overall, 66% and 73.5% of patients received antibiotics before and upon admission to ICU, respectively. Ceftriaxone, metronidazole and meropenem were commonly prescribed antibiotics. More than 84% of Enterobacterales were resistant to ciprofloxacin and trimethoprim-sulfamethoxazole, and 2.90% were resistant to meropenem. MRSA isolates showed a high rate of resistance to gentamicin and erythromycin.ConclusionMDR bacteria are common in patients admitted to ICU. To reduce the risk associated with MDR, we recommend use of simple screening methods to screen for MDR at ICU admission as part of infection control and prevention.

Air dispersal of meticillin-resistant Staphylococcus aureus in residential care homes for the elderly: implications for transmission during the COVID-19 pandemic

Meticillin-resistant Staphylococcus aureus (MRSA) infections are rampant in hospitals and residential care homes for the elderly (RCHEs). To analyse the prevalence of MRSA colonization among residents and staff, and degree of environmental contamination and air dispersal of MRSA in RCHEs. Epidemiological and genetic analysis by whole-genome sequencing (WGS) in 12 RCHEs in Hong Kong. During the COVID-19 pandemic (from September to October 2021), 48.7% (380/781) of RCHE residents were found to harbour MRSA at any body site, and 8.5% (8/213) of staff were nasal MRSA carriers. Among 239 environmental samples, MRSA was found in 39.0% (16/41) of randomly selected resident rooms and 31.3% (62/198) of common areas. The common areas accessible by residents had significantly higher MRSA contamination rates than those that were not accessible by residents (37.2%, 46/121 vs. 22.1%, 17/177, P=0.028). Of 124 air samples, nine (7.3%) were MRSA-positive from four RCHEs. Air dispersal of MRSA was significantly associated with operating indoor fans in RCHEs (100%, 4/4 vs. 0%, 0/8, P=0.002). WGS of MRSA isolates collected from residents, staff and environmental and air samples showed that ST 1047 (CC1) lineage 1 constituted 43.1% (66/153) of all MRSA isolates. A distinctive predominant genetic lineage of MRSA in each RCHE was observed, suggestive of intra-RCHE transmission rather than clonal acquisition from the catchment hospital. MRSA control in RCHEs is no less important than in hospitals. Air dispersal of MRSA may be an important mechanism of dissemination in RCHEs with operating indoor fans.

Gastrointestinal colonization of meticillin-resistant Staphylococcus aureus: an unrecognized burden upon hospital infection control

Meticillin-resistant Staphylococcus aureus (MRSA) has become endemic in many healthcare settings. To analyse the incidence, risk factors, outcomes, and genomic relatedness of patients with newly diagnosed gastrointestinal colonization of MRSA. Epidemiology and genetic analysis by whole-genome sequencing (WGS) in a hospital network in Hong Kong. Between October 1st, 2015 and December 31st, 2018, a total of 919 (2.7%) of 34,667 patients had newly diagnosed gastrointestinal MRSA colonization by admission screening. The incidence was 0.67 ± 0.32 per 1000 patient-days per quarter. Including patients with gastrointestinal MRSA colonization, the overall burden of MRSA increased by 59.2%, with an addition of 4727 MRSA patient-days during the study period. Patients referred from residential care home for the elderly, with history of hospitalization in the past six months, and consumption of fluoroquinolones, cephalosporins, and proton-pump inhibitors in the preceding six months were found to be independent risk factors by multivariate analysis in the case-control analysis. The median survival of cases was significantly shorter than that of controls (860 vs 1507 days, P < 0.001). Of 919 patients, 127 (13.8%) developed symptomatic MRSA infection in a median of 112 days. Of 19 patients with paired MRSA faecal and blood culture isolates subjected to WGS, clonality was found in 16 (84.2%) pairs of MRSA isolates. MRSA ST45 constituted 44.7% (17/38) of MRSA isolates. Gastrointestinal MRSA colonization may contribute to adverse clinical outcomes and pose an unrecognized burden upon hospital infection control.

Joint Healthcare Infection Society (HIS) and Infection Prevention Society (IPS) guidelines for the prevention and control of meticillin-resistant Staphylococcus aureus (MRSA) in healthcare facilities

Joint Healthcare Infection Society (HIS) and Infection Prevention Society (IPS) guidelines for the prevention and control of meticillin-resistant Staphylococcus aureus (MRSA) in healthcare facilities

Meticillin-resistant Staphylococcus aureus transmission among healthcare workers, patients and the environment in a large acute hospital under non-outbreak conditions investigated using whole-genome sequencing

The role of meticillin-resistant Staphylococcus aureus (MRSA) colonization of healthcare workers (HCWs), patients and the hospital environment in MRSA transmission in non-outbreak settings is poorly understood. To investigate transmission events (TEs) involving HCWs, patients and the environment under non-outbreak conditions in a hospital with a history of endemic MRSA using whole-genome sequencing (WGS). HCW (N= 326) and patient (N= 388) volunteers on nine wards were tested for nasal and oral MRSA colonization over two years. Near-patient environment (N= 1164), high-frequency touch sites (N= 810) and air (N= 445) samples were screened for MRSA. Representative MRSA and clinical isolates were analysed by WGS and core-genome multi-locus sequence typing (cgMLST). Closely related isolates (≤24 allelic differences) were segregated into related isolated groups (RIGs). In total, 155 MRSA were recovered: clinical isolates (N= 41), HCWs (N= 22), patients (N= 37), environmental isolates (N= 55). Nine clonal complexes (CCs) were identified among 110/155 MRSA sequenced with 77/110 assigned to CC22. Seventy-nine MRSA segregated into 17 RIGs. Numerous potential TEs were associated with CC22-MRSA (RIGs 1-15), CC45-MRSA (RIG-16) and CC8-MRSA (RIG-17). RIG-1, (the largest RIG) contained 24 ST22-MRSA-IVh from six HCWs, six patients, four clinical and eight environmental samples recovered over 17 months involving 7/9 wards. TEs involving HCW-to-patient, HCW-to-HCW, patient-to-patient and environmental contamination by HCW/patient isolates were evident. HCW, patient, clinical and environmental isolates were identified in four, nine, seven and 13 RIGs, respectively, with 12/13 of these containing isolates closely related to HCW and/or patient isolates. WGS detected numerous potential hospital MRSA TEs involving HCWs, patients and the environment under non-outbreak conditions.

Intranasal octenidine and universal chlorhexidine bathing can reduce meticillin-resistant Staphylococcus aureus acquisition in an extended care facility in Singapore

Meticillin-resistant Staphylococcus aureus (MRSA) is prevalent in extended care facilities. We conducted a quasi-experimental before-after study in a 100-bed rehabilitation hospital, from January 2013 to June 2019. Universal chlorhexidine bathing was implemented throughout the period, with intranasal octenidine for MRSA colonizers added from September 2017. Interrupted time-series with segmented regression analysis revealed that after adjusting for at-admission MRSA colonization and hand hygiene compliance, a constant trend was observed pre implementation of intranasal octenidine (adjusted mean coefficient: 0.012; 95% confidence interval: -0.037 to 0.06), with an immediate decrease with implementation (-2.145; -0.248 to -0.002; P= 0.033), followed by a significant reduction in MRSA acquisition post implementation (-0.125; -0.248 to -0.002; P= 0.047).

Protecting patients from infection: Improving topical prophylaxis compliance on surgical wards.

At a medium-sized district general hospital in the heart of England, it was identified that compliance to the administration of topical prophylaxis on three general surgery wards had reduced to 23%, following implementation of an electronic medication prescription record. Therefore, a quality improvement project was commenced to improve this compliance to protect patients from meticillin-resistant Staphylococcus aureus (MRSA) colonisation and associated bacteraemia. To improve compliance of topical prophylaxis administration on three surgical wards to protect patients from infection. Quality improvement plan - do - study - act (PDSA) cycles evaluated the effectiveness of four different strategies from baseline data which was 23% compliant in December 2016. These included teaching and communication strategies, prompts in medical notes, discontinuation of Mupirocin 2% nasal ointment as part of the topical prophylaxis regime and discontinuation of the topical wash lotion from requiring a prescription. The compliance of prophylaxis administration increased consistently throughout from 23% in December 2016 to 92% in March 2018. Consequently, the number of patients that developed a MRSA colonisation on the three wards reduced by 54%, from 13 in the 12 months before the study to six in the 12 months after the study. This study led to a change in the Trust MRSA Policy to better protect patients from infection, particularly surgical site infection and MRSA bacteraemia. It suggests that quality improvement methodology has a place in infection prevention practice.

Danish experience of meticillin-resistant Staphylococcus aureus eradication with emphasis on nose–throat colonization and supplementary systemic antibiotic treatment

This study aimed to evaluate the Danish Board of Health's guidance for treating the carriage of meticillin-resistant Staphylococcus aureus (MRSA), focusing on nose-throat carriage and use of supplementary systemic antibiotics. The results of MRSA eradication treatment among 358 patients were analysed, focusing on those with nose (N=58) or throat (N=183) MRSA colonization. The Danish guidance for MRSA treatment was found to be more successful in patients with nose colonization (66%) compared with throat colonization (41%), despite the fact that the cumulative eradication rates were equal after three treatment cycles (71% vs 73%). This study found that supplementation of colonization treatment with systemic antibiotics does not have a positive effect.

An outbreak of meticillin-resistant Staphylococcus aureus colonization in a neonatal intensive care unit: use of a case–control study to investigate and control it and lessons learnt

To describe the investigation and management of a meticillin-resistant Staphylococcus aureus (MRSA) outbreak on a neonatal intensive care unit (NICU) and the lessons learnt. This was an outbreak report and case-control study conducted in a 40-cot NICU in a tertiary referral hospital and included all infants colonized/infected with gentamicin-resistant MRSA. Standard infection-control measures including segregation of infants, barrier precautions, enhanced cleaning, assessment of staff practice including hand hygiene, and increased MRSA screening of infants were implemented. Continued MRSA acquisitions led to screening of all NICU staff. A case-control study was performed to assess staff contact with colonized babies and inform the management of the outbreak. Eight infants were colonized with MRSA (spa type t2068), one of whom subsequently developed an MRSA bacteraemia. MRSA colonization was significantly associated with lower gestational age; lower birthweight and with being a twin. Three nurses were MRSA colonized but only one nurse (45) was colonized with MRSA spa type t2068. Multivariable logistic regression analysis identified being cared for by nurse 45 as an independent risk factor for MRSA colonization. Lack of accurate recording of which nurses looked after which infants (and when) made identification of the risk posed by being cared for by particular nurses difficult. If this had been clearer, it may have enabled earlier identification of the colonized nurse, avoiding subsequent cases. This study highlights the benefit of using a case-control study, which showed that most nurses had no association with colonized infants.

Clonal expansion of community-associated meticillin-resistant Staphylococcus aureus (MRSA) in people who inject drugs (PWID): prevalence, risk factors and molecular epidemiology, Bristol, United Kingdom, 2012 to 2017.

Background: In 2015, Bristol (South West England) experienced a large increase in cases of meticillin-resistant Staphylococcus aureus (MRSA) infection in people who inject drugs (PWID).Aim: We aimed to characterise and estimate the prevalence of MRSA colonisation among PWID in Bristol and test evidence of a clonal outbreak.Methods: PWID recruited through an unlinked-anonymous community survey during 2016 completed behavioural questionnaires and were screened for MRSA. Univariable logistic regression examined associations with MRSA colonisation. Whole-genome sequencing used lineage-matched MRSA isolates, comparing PWID (screening and retrospective bacteraemia samples from 2012-2017) with non-PWID (Bristol screening) in Bristol and national reference laboratory database samples.Results: The MRSA colonisation prevalence was 8.7% (13/149) and was associated with frequently injecting in public places (odds ratio (OR): 5.5; 95% confidence interval (CI):1.34–22.70), recent healthcare contact (OR: 4.3; 95% CI: 1.34–13.80) and injecting in groups of three or more (OR: 15.8; 95% CI: 2.51–99.28). People reporting any one of: injecting in public places, injection site skin and soft tissue infection or hospital contact accounted for 12/13 MRSA positive cases (sensitivity 92.3%; specificity 51.5%). Phylogenetic analysis identified a dominant clade associated with infection and colonisation among PWID in Bristol belonging to ST5-SCCmecIVg.Conclusions: MRSA colonisation in Bristol PWID is substantially elevated compared with general population estimates and there is evidence of clonal expansion, community-based transmission and increased infection risk related to the colonising strain. Targeted interventions, including community screening and suppression therapy, education and basic infection control are needed to reduce MRSA infections in PWID.

High rates of meticillin-resistant Staphylococcus aureus among asylum seekers and refugees admitted to Helsinki University Hospital, 2010 to 2017.

IntroductionAntimicrobial resistance is increasing rapidly in countries with low hygiene levels and poorly controlled antimicrobial use. The spread of resistant bacteria poses a threat to healthcare worldwide. Refugees and migrants from high-prevalence countries may add to a rise in multidrug-resistant (MDR) bacteria in low-prevalence countries. However, respective data are scarce.MethodsWe retrospectively collected microbiological and clinical data from asylum seekers and refugees treated at Helsinki University Hospital between January 2010 and August 2017.ResultsOf 447 asylum seekers and refugees (Iraq: 46.5%; Afghanistan: 10.3%; Syria: 9.6%, Somalia: 6.9%); 45.0% were colonised by MDR bacteria: 32.9% had extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-PE), 21.3% meticillin-resistant Staphylococcus aureus (MRSA), 0.7% carbapenemase-producing Enterobacteriaceae (CPE), 0.4% multiresistant Pseudomonas aeruginosa (MRPA), 0.4% multiresistant Acinetobacter baumannii (MRAB); no vancomycin-resistant Enterococcus (VRE) were found. Two or more MDR bacteria strains were recorded for 12.5% of patients. Multivariable analysis revealed geographical region and prior surgery outside Nordic countries as risk factors of MRSA colonisation. Young age (< 6 years old), short time from arrival to first sample, and prior hospitalisation outside Nordic countries were risk factors of ESBL-PE colonisation.ConclusionWe found MDR bacterial colonisation to be common among asylum seekers and refugees arriving from current conflict zones. In particular we found a high prevalence of MRSA. Refugees and migrants should, therefore, be included among risk populations requiring MDR screening and infection control measures at hospitals.

Successful termination of sustained transmission of resident MRSA following extensive NICU refurbishment: an intervention study

Neonatal sepsis is a leading cause of morbidity and mortality in neonatal units worldwide. Meticillin-resistant Staphylococcus aureus (MRSA) has become a leading causative pathogen. Many neonatal units experience endemic colonization and infection of their infants, which is often very challenging to successfully eradicate. To assess the impact of neonatal unit refurbishment and redesign on endemic MRSA colonization and infection. A retrospective review was carried out over an eight-year period in a 14-cot, level 2-3 neonatal unit in University Hospital Galway, a large university teaching hospital in the West of Ireland. Surveillance, colonization, and infection data for a four-year period pre and four-year period post neonatal unit refurbishment are described. Clinical and microbiological data were collected on all MRSA-colonized and -infected infants between 2008 and 2015. Molecular typing data are available for MRSA isolates. An interrupted time-series design was used, with unit refurbishment as the intervention. Our neonatal unit had a pattern of sustained transmission of endemic resident MRSA strains which we could not eradicate despite repeated standard infection control interventions. Complete unit refurbishment led to successful termination of sustained transmission of these strains. Colonization decreased and no infants were actively infected post refurbishment of the unit. We report successful termination of sustained transmission of endemic strains of MRSA from our neonatal unit following complete unit redesign and refurbishment.

Frequent MRSA nasal colonization among hospitalized children and their parents in Angola and São Tomé and Príncipe

The prevalence of nosocomial meticillin-resistant Staphylococcus aureus (MRSA) was previously estimated as 23% in a paediatric hospital in Luanda, Angola and 18% in a general hospital in São Tomé and Príncipe. To evaluate the prevalence of S.aureus/MRSA colonization among hospitalized children and their parents at two hospitals in Angola and São Tomé and Príncipe. In 2017, 127 hospitalized children and 129 of their parents had nasal swabs for S.aureus/MRSA carriage in the two countries. The isolates were tested for the presence of the mecA and Panton-Valentine leukocidin (PVL) genes, and characterized by pulsed-field gel electrophoresis (PFGE), spa typing, multi-locus sequence typing and SCCmec typing. Twenty of 127 children (15.7%) and 13 of 129 parents (10.1%) were MRSA nasal carriers. Three lineages comprised 88% of the MRSA isolates: (i) PFGE A-ST5-SCCmec IVa (N=15; 45%), associated with spa type t105, recovered in Angola alone; (ii) PFGE N-ST8-IV/V (N=7; 21%), associated with spa types t008/t121, recovered in São Tomé and Príncipe alone; and (iii) PFGE B-ST88-IVa (N=7; 21%), associated with spa types t325/t786, present in both countries. Fifteen child/guardian pairs were colonized with identical MRSA (N=8) or meticillin-susceptible S.aureus (N=7) strains. PVL was detected in 25% of isolates, including two MRSA (ST30-V and ST8-IVa). Hospitalized children and their parents are important reservoirs of MRSA. Infection control measures should focus on parents in order to minimize the spread of MRSA to the community.

Persistence of meticillin-resistant Staphylococcus aureus carriage in re-admitted patients

A retrospective cohort study was conducted to investigate the duration and risk factors for persistence of meticillin-resistant Staphylococcus aureus (MRSA) colonization among known carriers who were re-admitted to hospital. MRSA carriage persisted in a high proportion of known carriers up to two years after their last date of discharge, and re-admission screening should be performed for at least this duration. A targeted screening approach should focus on older patients with a history of long inpatient stays, who are at higher risk of persistent carriage. Timely discharge planning is important in reducing the risk of persistent MRSA colonization among known carriers.

Randomized controlled trial of honey versus mupirocin to decolonize patients with nasal colonization of meticillin-resistant Staphylococcus aureus

Mupirocin is used specifically for the eradication of nasal meticillin-resistant Staphylococcus aureus (MRSA), but increasing mupirocin resistance restricts its repeated use. The antibacterial effects of manuka honey have been established invitro; antibacterial activity of other honeys has also been reported. To describe the learning experience from a randomized controlled trial (RCT) comparing the efficacy of medical-grade honey (MGH) with mupirocin 2% for the eradication of nasal MRSA. Patients colonized in the nose with MRSA and age ≥18 years were recruited. Participants received either one or two courses of MGH or mupirocin 2%, three times per day for five consecutive days. The proportion of patients who were decolonized after one or two courses of treatment was not significantly different between MGH [18/42; 42.8%; 95% confidence interval (CI): 27.7-59.0] and mupirocin 2% (25/44; 56.8%; 95% CI: 41.0-71.7). Non-nasal MRSA colonization was significantly associated with persistent nasal colonization (odds ratio: 5.186; 95% CI: 1.736-5.489; P=0.003). The rate of new acquisition of mupirocin resistance was 9.75%. Although not significant, a decolonization rate of 42.8% for MGH was impressive. Our findings suggest that this strategy, which has the potential to combat antimicrobial resistance, should be assessed in similar but larger studies.

Evaluation of single vs pooled swab cultures for detecting MRSA colonization

The costs and laboratory workload arising from meticillin-resistant Staphylococcus aureus (MRSA) screening could be reduced markedly by processing nose, throat and skin swabs from one person in a single culture broth (specimen pooling). The purpose of this study was to evaluate the sensitivities and times for MRSA detection using a variety of approaches to processing of individual and pooled swabs. Four hundred and seventeen swabs from 139 subjects with a history of MRSA colonization (three swabs per subject - nose, throat and skin) were submitted. Swabs were suspended in 200-μL sterile saline, and these suspensions were used individually and as pooled samples to inoculate two different chromogenic media [MRSA SMART (bioMėrieux, Marcy-l'Étoile, Paris, France) and CHROMagar MRSA (CHROMagar, Paris, France)] and Todd-Hewitt Broth; the latter cultures were then subcultured on to the same chromogenic media. MRSA was detected from at least one specimen in 75 subjects (50.4%). The diagnostic sensitivities of pooled surveillance cultures compared with single cultures were 97% and 93% for direct and enrichment cultures, respectively. Enrichment culture of either individual or pooled samples had no benefit compared with direct culture (P>0.05). Pooling of MRSA screening swabs for either direct culture on chromogenic agar or enrichment culture is suitable for routine use.

Evaluation of sedation-related medication errors in patients on contact isolation in the intensive care unit

Patients in intensive care units (ICUs) may be placed on contact isolation for meticillin-resistant Staphylococcus aureus (MRSA) colonization to prevent transmission. Prior studies suggest that isolated patients may receive substandard care compared with non-isolated patients. An optimal level of sedation is required to facilitate mechanical ventilation (MV) and to minimize adverse outcomes. To determine if patients on MV and isolated for MRSA colonization are at increased risk of oversedation compared with non-isolated patients. Retrospective chart review of adult patients on MV who received an MRSA nasal polymerase chain reaction assay and sedation within 24 and 48h of ICU admission, respectively. Endpoints included rate of inappropriate sedation, length of ICU stay, length of time on MV, and incidence of ventilator-associated complications. In total, 226 patients were included (114 MRSA positive, 112 MRSA negative). Baseline demographics were similar between the groups, with the exception of ICU admission diagnosis. Fifty-six (55%) isolated patients experienced inappropriate sedation compared with 49 (50%) non-isolated patients (P=0.482). Isolated patients spent longer in the ICU (10.4 vs 6.8 days, P=0.0006), longer on MV (8.98 vs 4.81 days, P<0.001), and required tracheostomies more frequently [37 (32%) vs 14 (13%), P=0.0003] than non-isolated patients. Isolated patients were not at increased risk of oversedation compared with non-isolated patients. There was an association between the use of contact isolation for MRSA nares colonization and prolonged ICU stay and prolonged MV.