Quantifying the impact of extranasal testing of body sites for methicillin-resistant Staphylococcus aureus colonization at the time of hospital or intensive care unit admission

Antimicrobial Susceptibility Profile of Methicillin-Resistant Staphylococcus Aureus Isolated from Clinical Samples at Bac Ninh Provincial General Hospital, Vietnam

Purpose

Staphylococcus aureus, including methicillin-resistant Staphylococcus aureus (MRSA) strain, can become resistant to all classes of clinically available antibiotics and causes skin infections and severe infections in the lungs, heart, and bloodstream. The study aimed to evaluate antimicrobial susceptibility patterns and MRSA exhibiting multidrug resistance obtained through a microbiological culture of clinical specimens at Bac Ninh Provincial General Hospital in Bac Ninh Province, Vietnam.

Methods

We employed a cross-sectional analysis at Bac Ninh Provincial General Hospital in Vietnam. 15,232 clinical samples from inpatients were examined. S. aureus isolates were identified using established protocols and tested for MRSA and antibiotic susceptibility. Data was analyzed using R software, with statistical calculations to assess associations between variables.

Results

Staphylococcus aureus was isolated from 417 samples (2.7%), with 77.2% being MRSA and 22.8% methicillin-susceptible Staphylococcus aureus (MSSA). Significant sources of MRSA were wounds (64.6%) and the surgical unit (50%) according to sample types and hospital wards, respectively. S. aureus showed high resistance rates, the highest being azithromycin (83.2%), and was fully susceptible to vancomycin. Among 294 multidrug-resistant (MDR) strains, the prevalence was 82.0% in MRSA and 18.0% in MSSA.

Conclusion

The study highlights widespread antimicrobial resistance among MRSA isolates from a provincial hospital in Vietnam, emphasizing the urgent need for antibiotic surveillance, formulation of antibiotic policies, and preventive measures to tackle the increasing prevalence of multidrug-resistant MRSA.

Detection of Staphylococcus aureus from nares of elderly living in a Brazilian nursing home

Asymptomatically nasal colonization by Staphylococcus aureus is a well-established risk factor for S. aureus infections. The aimed of the study was to identify the prevalence and factors associated with nasal carriage of S. aureus and Methicillin-resistant S. aureus (MRSA) from individuals residing in one Brazilian nursing home (NH). Three time-separate nasal swab collections were obtained from the elderly enrolled. The S. aureus isolates identified were submitted to Antimicrobial Susceptibility test (AST). The study showed a high prevalence of S. aureus (n = 9; 60%) and MRSA (n = 4; 26.7%) among elderly. Resistance to erythromycin was the most detected. S. aureus or MRSA colonization could not be associated to the data collected on demographics, personal habits, and medical history of the participants. Despite the small number of individuals enrolled, our study can contribute to improve the control of S. aureus and MRSA dissemination within the community, especially among the most vulnerable like the elderly.

Decolonization in Nursing Homes to Prevent Infection and Hospitalization

BACKGROUND

Nursing home residents are at high risk for infection, hospitalization, and colonization with multidrug-resistant organisms.

METHODS

We performed a cluster-randomized trial of universal decolonization as compared with routine-care bathing in nursing homes. The trial included an 18-month baseline period and an 18-month intervention period. Decolonization entailed the use of chlorhexidine for all routine bathing and showering and administration of nasal povidone-iodine twice daily for the first 5 days after admission and then twice daily for 5 days every other week. The primary outcome was transfer to a hospital due to infection. The secondary outcome was transfer to a hospital for any reason. An intention-to-treat (as-assigned) difference-in-differences analysis was performed for each outcome with the use of generalized linear mixed models to compare the intervention period with the baseline period across trial groups.

RESULTS

Data were obtained from 28 nursing homes with a total of 28,956 residents. Among the transfers to a hospital in the routine-care group, 62.2% (the mean across facilities) were due to infection during the baseline period and 62.6% were due to infection during the intervention period (risk ratio, 1.00; 95% confidence interval [CI], 0.96 to 1.04). The corresponding values in the decolonization group were 62.9% and 52.2% (risk ratio, 0.83; 95% CI, 0.79 to 0.88), for a difference in risk ratio, as compared with routine care, of 16.6% (95% CI, 11.0 to 21.8; P<0.001). Among the discharges from the nursing home in the routine-care group, transfer to a hospital for any reason accounted for 36.6% during the baseline period and for 39.2% during the intervention period (risk ratio, 1.08; 95% CI, 1.04 to 1.12). The corresponding values in the decolonization group were 35.5% and 32.4% (risk ratio, 0.92; 95% CI, 0.88 to 0.96), for a difference in risk ratio, as compared with routine care, of 14.6% (95% CI, 9.7 to 19.2). The number needed to treat was 9.7 to prevent one infection-related hospitalization and 8.9 to prevent one hospitalization for any reason.

CONCLUSIONS

In nursing homes, universal decolonization with chlorhexidine and nasal iodophor led to a significantly lower risk of transfer to a hospital due to infection than routine care. (Funded by the Agency for Healthcare Research and Quality; Protect ClinicalTrials.gov number, NCT03118232.).

SHEA/IDSA/APIC Practice Recommendation: Strategies to prevent methicillin-resistant Staphylococcus aureus transmission and infection in acute-care hospitals: 2022 Update

Previously published guidelines have provided comprehensive recommendations for detecting and preventing healthcare-associated infections (HAIs). The intent of this document is to highlight practical recommendations in a concise format designed to assist acute-care hospitals in implementing and prioritizing efforts to prevent methicillin-resistant Staphylococcus aureus (MRSA) transmission and infection. This document updates the "Strategies to Prevent Methicillin-Resistant Staphylococcus aureus Transmission and Infection in Acute Care Hospitals" published in 2014.1 This expert guidance document is sponsored by the Society for Healthcare Epidemiology of America (SHEA). It is the product of a collaborative effort led by SHEA, the Infectious Diseases Society of America (IDSA), the Association for Professionals in Infection Control and Epidemiology (APIC), the American Hospital Association (AHA), and The Joint Commission, with major contributions from representatives of a number of organizations and societies with content expertise.

Clinical Utility of Dual Anterior Nares and Oropharynx MRSA Screening PCR for Patients with Suspected Pneumonia

We reviewed the electronic health records of 1,419 inpatients with anterior nares (AN) and oropharynx (OP) MRSA PCR tests. Concordance was 96.5%. In discordant cases, AN negative-OP positive results increased detection of probable MRSA pneumonia by only 0.3%. A dual testing approach has limited utility in detecting MRSA pneumonia and increases resource utilization.

Emerging Paradigms in the Prevention of Surgical Site Infection: The Patient Microbiome and Antimicrobial Resistance

This article summarizes new scientific evidence on the pathogenesis of surgical site infection, including the roles of the patient microbiome and antimicrobial resistance, and reviews changes in guidelines and clinical practices for prevention.

Comparison of Transcriptional Signatures of Three Staphylococcal Superantigenic Toxins in Human Melanocytes

Staphylococcus aureus, a gram-positive bacterium, causes toxic shock through the production of superantigenic toxins (sAgs) known as Staphylococcal enterotoxins (SE), serotypes A-J (SEA, SEB, etc.), and toxic shock syndrome toxin-1 (TSST-1). The chronology of host transcriptomic events that characterizes the response to the pathogenesis of superantigenic toxicity remains uncertain. The focus of this study was to elucidate time-resolved host responses to three toxins of the superantigenic family, namely SEA, SEB, and TSST-1. Due to the evolving critical role of melanocytes in the host’s immune response against environmental harmful elements, we investigated herein the transcriptomic responses of melanocytes after treatment with 200 ng/mL of SEA, SEB, or TSST-1 for 0.5, 2, 6, 12, 24, or 48 h. Functional analysis indicated that each of these three toxins induced a specific transcriptional pattern. In particular, the time-resolved transcriptional modulations due to SEB exposure were very distinct from those induced by SEA and TSST-1. The three superantigens share some similarities in the mechanisms underlying apoptosis, innate immunity, and other biological processes. Superantigen-specific signatures were determined for the functional dynamics related to necrosis, cytokine production, and acute-phase response. These differentially regulated networks can be targeted for therapeutic intervention and marked as the distinguishing factors for the three sAgs.

Modelling methicillin-resistant Staphylococcus aureus decolonization: interactions between body sites and the impact of site-specific clearance

Methicillin-resistant Staphylococcus aureus (MRSA) can colonize multiple body sites, and carriage is a risk factor for infection. Successful decolonization protocols reduce disease incidence; however, multiple protocols exist, comprising diverse therapies targeting multiple body sites, and the optimal protocol is unclear. Standard methods cannot infer the impact of site-specific components on successful decolonization. Here, we formulate a Bayesian coupled hidden Markov model, which estimates interactions between body sites, quantifies the contribution of each therapy to successful decolonization, and enables predictions of the efficacy of therapy combinations. We applied the model to longitudinal data from a randomized controlled trial (RCT) of an MRSA decolonization protocol consisting of chlorhexidine body and mouthwash and nasal mupirocin. Our findings (i) confirmed nares as a central hub for MRSA colonization and nasal mupirocin as the most crucial therapy and (ii) demonstrated all components contributed significantly to the efficacy of the protocol and the protocol reduced self-inoculation. Finally, we assessed the impact of hypothetical therapy improvements in silico and found that enhancing MRSA clearance at the skin would yield the largest gains. This study demonstrates the use of advanced modelling to go beyond what is typically achieved by RCTs, enabling evidence-based decision-making to streamline clinical protocols.

The Effect of Systemic Antibiotics for Suppurative Skin and Soft Tissue Infections on Skin Microbiome

Background

Skin and soft tissue infections (SSTIs) are very common bacterial infections. There are few data on the microbiome of persons with and without SSTIs and the effects of systemic antibiotic therapy.

Methods

We sampled the skin microbiome from 10 outpatients with acute suppurative SSTI before and after systemic antibiotic therapy and enrolled 10 matched controls. Samples were collected at 6 skin body sites (occipital scalp, axilla, interdigital hand web spaces, gluteal crease, inguinal creases, and popliteal fossa), 2 mucosal sites (throat, anterior nares), and the site of skin infection (for case subjects) at baseline and a week later after abscess incision, drainage, and oral antibiotics.

Result

Among 10 SSTI cases, mean age was 41.5 years and 3 had diabetes mellitus. The gluteal crease at baseline had higher α-diversity in controls vs cases (P = .039); β-diversity analysis showed significant differences in overall bacterial community composition (P = .046). However, at other body sites there were no significant differences by either α- or β-diversity. Systemic antibiotic use did not affect body site diversity indices except at the SSTI site (α-diversity increased, P = .001).

Conclusions

We surprisingly found no significant differences in microbiome comparing noninfected skin sites before and after systemic SSTI antibiotic therapy nor significant differences at noninfected skin sites between SSTI cases and uninfected controls. We also found minimal significant differences between microbiome diversity and bacterial signatures at noninfected skin sites between patients with acute skin infection and uninfected controls. Our findings challenge the dogma that systemic antibiotics impact the skin microbiome.

Approach to the Patient with a Skin and Soft Tissue Infection

The diagnosis of a skin and soft tissue infection (SSTI) requires careful attention to a patient's history, physical examination, and diagnostic test results. We review for many bacterial, viral, fungal, and parasitic pathogens that cause SSTIs the clues for reaching a diagnosis, including reported past medical history, hobbies and behaviors, travel, insect bites, exposure to other people and to animals, environmental exposures to water, soil, or sand, as well as the anatomic site of skin lesions, their morphology on examination, and their evolution over time. Laboratory and radiographic tests are discussed that may be used to confirm a specific diagnosis.

Decolonization of Staphylococcus aureus

Staphylococcus aureus infections are associated with increased morbidity, mortality, hospital stay, and health care costs. S aureus colonization has been shown to increase risk for invasive and noninvasive infections. Decolonization of S aureus has been evaluated in multiple patient settings as a possible strategy to decrease the risk of S aureus transmission and infection. In this article, we review the recent literature on S aureus decolonization in surgical patients, patients with recurrent skin and soft tissue infections, critically ill patients, hospitalized non-critically ill patients, dialysis patients, and nursing home residents to inform clinical practice.

Staphylococcal Skin and Soft Tissue Infections

Staphylococcus aureus is the most common bacteria causing purulent skin and soft tissue infections. Many disease-causing S aureus strains are methicillin resistant; thus, empiric therapy should be given to cover methicillin-resistant S aureus. Bacterial wound cultures are important for characterizing local susceptibility patterns. Definitive antibiotic therapy is warranted, although there are no compelling data demonstrating superiority of any one antibiotic over another. Antibiotic choice is predicated by the infection severity, local susceptibility patterns, and drug-related safety, tolerability, and cost. Response to therapy is expected within the first days; 5 to 7 days of therapy is typically adequate to achieve cure.

The SHIELD Orange County Project: Multidrug-resistant Organism Prevalence in 21 Nursing Homes and Long-term Acute Care Facilities in Southern California

BACKGROUND

Multidrug-resistant organisms (MDROs) spread between hospitals, nursing homes (NHs), and long-term acute care facilities (LTACs) via patient transfers. The Shared Healthcare Intervention to Eliminate Life-threatening Dissemination of MDROs in Orange County is a regional public health collaborative involving decolonization at 38 healthcare facilities selected based on their high degree of patient sharing. We report baseline MDRO prevalence in 21 NHs/LTACs.

METHODS

A random sample of 50 adults for 21 NHs/LTACs (18 NHs, 3 LTACs) were screened for methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus spp. (VRE), extended-spectrum β-lactamase-producing organisms (ESBL), and carbapenem-resistant Enterobacteriaceae (CRE) using nares, skin (axilla/groin), and peri-rectal swabs. Facility and resident characteristics associated with MDRO carriage were assessed using multivariable models clustering by person and facility.

RESULTS

Prevalence of MDROs was 65% in NHs and 80% in LTACs. The most common MDROs in NHs were MRSA (42%) and ESBL (34%); in LTACs they were VRE (55%) and ESBL (38%). CRE prevalence was higher in facilities that manage ventilated LTAC patients and NH residents (8% vs <1%, P < .001). MDRO status was known for 18% of NH residents and 49% of LTAC patients. MDRO-colonized adults commonly harbored additional MDROs (54% MDRO+ NH residents and 62% MDRO+ LTACs patients). History of MRSA (odds ratio [OR] = 1.7; confidence interval [CI]: 1.2, 2.4; P = .004), VRE (OR = 2.1; CI: 1.2, 3.8; P = .01), ESBL (OR = 1.6; CI: 1.1, 2.3; P = .03), and diabetes (OR = 1.3; CI: 1.0, 1.7; P = .03) were associated with any MDRO carriage.

CONCLUSIONS

The majority of NH residents and LTAC patients harbor MDROs. MDRO status is frequently unknown to the facility. The high MDRO prevalence highlights the need for prevention efforts in NHs/LTACs as part of regional efforts to control MDRO spread.

High Prevalence of Multidrug-Resistant Organism Colonization in 28 Nursing Homes: An "Iceberg Effect"

OBJECTIVE

Determine the prevalence of methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus spp. (VRE), extended-spectrum beta-lactamase producing organisms (ESBLs), and carbapenem-resistant Enterobacteriaceae (CRE) among residents and in the environment of nursing homes (NHs).

DESIGN

Point prevalence sampling of residents and environmental sampling of high-touch objects in resident rooms and common areas.

SETTING

Twenty-eight NHs in Southern California from 2016 to 2017.

PARTICIPANTS

NH participants in Project PROTECT, a cluster-randomized trial of enhanced bathing and decolonization vs routine care.

METHODS

Fifty residents were randomly sampled per NH. Twenty objects were sampled, including 5 common room objects plus 5 objects in each of 3 rooms (ambulatory, total care, and dementia care residents).

RESULTS

A total of 2797 swabs were obtained from 1400 residents in 28 NHs. Median prevalence of multidrug-resistant organism (MDRO) carriage per NH was 50% (range: 24%-70%). Median prevalence of specific MDROs were as follows: MRSA, 36% (range: 20%-54%); ESBL, 16% (range: 2%-34%); VRE, 5% (range: 0%-30%); and CRE, 0% (range: 0%-8%). A median of 45% of residents (range: 24%-67%) harbored an MDRO without a known MDRO history. Environmental MDRO contamination was found in 74% of resident rooms and 93% of common areas.

CONCLUSIONS AND IMPLICATIONS

In more than half of the NHs, more than 50% of residents were colonized with MDROs of clinical and public health significance, most commonly MRSA and ESBL. Additionally, the vast majority of resident rooms and common areas were MDRO contaminated. The unknown submerged portion of the iceberg of MDRO carriers in NHs may warrant changes to infection prevention and control practices, particularly high-fidelity adoption of universal strategies such as hand hygiene, environmental cleaning, and decolonization.

Methicillin-resistant Staphylococcus aureus colonization in patients undergoing primary total hip arthroplasty

Introduction. Nasal and skin colonization by methicillin-resistant Staphylococcus aureus (MRSA) are linked to a higher incidence of infection after total joint replacement. The prevalence of colonization is poorly defined in Latin American countries.Aim. The aim of the present study was to determine the prevalence of MRSA colonization in the nostrils and groin using real-time polymerase chain reaction (RT-PCR) in patients undergoing total hip arthroplasty (THA).Methodology. In this cross-sectional study, 146 patients undergoing THA between December 2015 and March 2017 in a tertiary-care university-affiliated hospital in Chile were screened for MRSA colonization before the procedure using RT-PCR independently in the nostrils and groin. Risk factors for colonization were documented.Results. Seven of the 146 (5 %) patients undergoing THA were carriers of MRSA in the nostrils and/or the groin. Recent antibiotic use was identified as a risk factor for colonization, OR=4.86 [95 % confidence interval (CI): 1.56-13.96]. Patients reporting at least one of the seven surveyed risk factors had an OR of 2.39 (95 % CI: 0.37-25.77) for colonization. MRSA colonization frequency was twofold higher in the groin as opposed to the nostrils (P=0.014).Conclusion. Five percent of the patients undergoing THA were identified as carriers of MRSA. Recent antibiotic use is a relevant risk factor for MRSA colonization in patients undergoing primary total hip arthroplasty.

Screening for and decolonization of Staphylococcus aureus carriers before total joint replacement is associated with lower S aureus prosthetic joint infection rates

BACKGROUND

Prosthetic joint infections (PJI) can be devastating postoperative complications after total joint replacement (TJR). The role of decolonization of Staphylococcus aureus carriers prior to surgery still remains unclear, and the most recent guidelines do not state a formal recommendation for such strategy. Our purpose was to seek further evidence supporting preoperative screening and S aureus decolonization in patients undergoing TJR.

METHODS

This was a quasiexperimental quality improvement study comparing a 5-year baseline of deep and organ-space PJIs (2005- 2010) to a 1-year intervention period (May 2015 to July 2016). The intervention consisted of nasal and throat screening for S aureus preoperatively and decolonization of carriers over 5 days prior to surgery.

RESULTS

Prior to the intervention, we identified 42 deep and/or organ-space PJIs in 8,505 patients undergoing TJR (0.5%). S aureus was the causal microorganism in 28 of 42 (66.6%) cases. During the intervention, 22.5% (424 of 1,883) of patients were S aureus carriers. The PJI rate was similar overall (0.4%, 7 of 1,883; odds ratio, 0.75; 95% confidence interval, 0.34-1.67; P = .58), but there was a significant reduction in S aureus PJI to only 1 case during the intervention (odds ratio, 0.15; 95% confidence interval, 0.004-0.94; P = .039).

CONCLUSIONS

Active screening for S aureus and decolonization of carriers prior to TJR was associated with a reduction in PJI due to S aureus, but no changes in overall PJI rates were observed.

Sustained fall in inpatient MRSA prevalence after a video-reflexive ethnography project; an observational study

BACKGROUND

Maintaining optimal infection prevention and control (IPC) in a busy, clinical environment is challenging. Video-reflexive ethnography (VRE) is a collaborative, interventionist approach to practice improvement. We hypothesised that giving clinicians opportunities to view and reflect on video footage of everyday ward activities would raise awareness of, and suggest strategies to reduce, pathogen transmission risks. We undertook a VRE project, between March and September 2013, in two tertiary hospital surgical wards, with persistently high methicillin resistant Staphylococcus aureus (MRSA) endemicity, despite previous IPC interventions.

METHODS

This study was a retrospective/prospective observational study, using interrupted time-series analyses, to assess the effects of the VRE project on hand hygiene compliance, inpatient MRSA infections (newly infected patients, per 1000 occupied bed days) and inpatient MRSA colonisation prevalence, measured by serial point prevalence surveys. Follow-up continued until June 2016.

RESULTS

The VRE project was associated with changes in IPC behaviour and outcomes. Hand hygiene compliance increased (from 62% to 75%; p < 0.0001) and MRSA colonisation prevalence decreased significantly, in both wards (baseline 42%; average post-VRE 12%; p=<0.0001), MRSA infection rate decreased in one ward. Interpretation of results was complicated by a potential confounding effect of unplanned environmental hydrogen peroxide decontamination (HPD). Improved hand hygiene compliance was a predicted outcome of VRE, but also a potential contributor to reduced MRSA transmission.

CONCLUSION

Separate contributions of VRE (the intervention), HPD and hand hygiene compliance were uncertain, but their combined effect was significantly reduced MRSA endemicity, which previously had been resistant to attempted IPC interventions.

Methicillin-resistant Staphylococcus aureus: an overview of basic and clinical research

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most successful modern pathogens. The same organism that lives as a commensal and is transmitted in both health-care and community settings is also a leading cause of bacteraemia, endocarditis, skin and soft tissue infections, bone and joint infections and hospital-acquired infections. Genetically diverse, the epidemiology of MRSA is primarily characterized by the serial emergence of epidemic strains. Although its incidence has recently declined in some regions, MRSA still poses a formidable clinical threat, with persistently high morbidity and mortality. Successful treatment remains challenging and requires the evaluation of both novel antimicrobials and adjunctive aspects of care, such as infectious disease consultation, echocardiography and source control. In this Review, we provide an overview of basic and clinical MRSA research and summarize the expansive body of literature on the epidemiology, transmission, genetic diversity, evolution, surveillance and treatment of MRSA.

Methicillin-Resistant Staphylococcus aureus Infection and Treatment Options

Methicillin-resistant Staphylococcus aureus (MRSA) is a leading cause of infection worldwide, including a wide array of both hospital- and community-acquired infections-most commonly bacteremia, upper and lower respiratory tract infection, skin and soft-tissue infection, osteomyelitis, and septic arthritis. This chapter describes the epidemiology of MRSA infection, its ability to confer antibiotic resistance and produce a wide array of virulence factors, and its pivotal role in human infection, especially cystic fibrosis. It also provides an introduction to the strategies for treatment of both chronic and acute MRSA infections.

Environmental Panels as a Proxy for Nursing Facility Patients With Methicillin-Resistant Staphylococcus aureus and Vancomycin-Resistant Enterococcus Colonization

Background

Most nursing facilities (NFs) lack methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE) surveillance programs due to limited resources and high costs. We investigated the utility of environmental screening of high-touch surfaces in patient rooms as a way to circumvent these challenges.

Methods

We compared MRSA and VRE culture data from high-touch surfaces in patients' rooms (14450 samples from 6 NFs) and ranked each site's performance in predicting patient colonization (7413 samples). The best-performing sites were included in a MRSA- and a VRE-specific panel that functioned as a proxy for patient colonization. Molecular typing was performed to confirm available concordant patient-environment pairs.

Results

We identified and validated a MRSA panel that consisted of the bed controls, nurse call button, bed rail, and TV remote control. The VRE panel included the toilet seat, bed controls, bed rail, TV remote control, and top of the side table. Panel colonization data tracked patient colonization. Negative predictive values were 89%-92% for MRSA and 82%-84% for VRE. Molecular typing confirmed a strong clonal type relationship in available concordant patient-environment pairs (98% for MRSA, 91% for VRE), pointing to common epidemiological patterns for environmental and patient isolates.

Conclusions

Environmental panels used as a proxy for patient colonization and incorporated into facility surveillance protocols can guide decolonization strategies, improve awareness of MRSA and VRE burden, and inform efforts to reduce transmission. Targeted environmental screening may be a viable surveillance strategy for MRSA and VRE detection in NFs.

Improved characterisation of MRSA transmission using within-host bacterial sequence diversity

Methicillin-resistant Staphylococcus aureus (MRSA) transmission in the hospital setting has been a frequent subject of investigation using bacterial genomes, but previous approaches have not yet fully utilised the extra deductive power provided when multiple pathogen samples are acquired from each host. Here, we used a large dataset of MRSA sequences from multiply-sampled patients to reconstruct colonisation of individuals in a high-transmission setting in a hospital in Thailand. We reconstructed transmission trees for MRSA. We also investigated transmission between anatomical sites on the same individual, finding that this either occurs repeatedly or involves a wide transmission bottleneck. We examined the between-subject bottleneck, finding considerable variation in the amount of diversity transmitted. Finally, we compared our approach to the simpler method of identifying transmission pairs using single nucleotide polymorphism (SNP) counts. This suggested that the optimum threshold for identifying a pair is 39 SNPs, if sensitivities and specificities are equally weighted.

MRSA Point Prevalence among Health Care Workers in German Rehabilitation Centers: A Multi-Center, Cross-Sectional Study in a Non-Outbreak Setting

People working in health care services have an increased risk of being infected with methicillin-resistant Staphylococcus aureus (MRSA), though little is known about the prevalence in rehabilitation centers. This cross-sectional study investigated the MRSA prevalence in employees from different rehabilitation centers and aimed to identify risk factors for MRSA transmission. We invited all staff (i.e., with and without patient contact from 22 participating rehabilitation centers; n = 2499) to participate. Study participation included a questionnaire on personal characteristics, lifestyle, personal and occupational risk factors for MRSA and nasal swabs taken by the study team. In total, 1005 persons participated in the study (response: 40.2%). Only four participants carried MRSA (0.40 (95% CI 0.00–1.00) per 100). MRSA carriage did not seem to be occupationally related, as it was found in different occupations with and without direct contact with MRSA patients, as well as in different clinics with different indications and patient clientele. We could not find a clear association between MRSA carriage and potential risk factors due to the low number of cases found. Genotyping revealed the spa types t032 (Barnim epidemic strain) and t1223. Our results suggest a low point prevalence of nasal MRSA colonization in a non-outbreak setting in employees from rehabilitation centers.

Prevalence and predictors of MRSA carriage among employees in a non-outbreak setting: a cross-sectional study in an acute care hospital

BACKGROUND

Health care workers have an increased risk of being infected with Methicillin-resistant Staphylococcus aureus (MRSA), though little information is available about how prevalent (dormant) MRSA colonization is among health care workers. The aim of this study was to estimate the prevalence and predictors of MRSA carriage in a non-outbreak setting in a university hospital in Germany.

METHODS

The entire staff of a university hospital heart center for cardiologic maximum medical care and cardiac surgery were invited to participate in a cross-sectional study (N = 575). The sampled population included health care workers as well as employees with no close patient contact.A questionnaire concerning personal and occupational risk factors as well as lifestyle and demographic factors was applied and nasal swabs were taken. In total 180 persons (31.3%) participated in the study.

RESULTS

The majority of study participants had close contact to patients at work (n = 149, 82.8%). Thereof, about one-third had contact to MRSA-patients (n = 53, 35.6%), and most reported wearing protective clothing (n = 44, 83.0%). None of the administrative staff tested positive for MRSA and only one in 149 persons (0.7%, CI 0.00-0.02) with close patient contact carried MRSA (strain CC1-MRSA-IV). This person had close contact to patients with MRSA, less than 1 year of work experience, and had been treated with antibiotics within the last 12 months.

CONCLUSION

The results of our study suggest low point prevalence rates of MRSA colonization in health care workers in a non-outbreak setting.

The effect of preoperative oral antibiotic use on the risk of periprosthetic joint infection after primary knee or hip replacement: a retrospective study with a 1-year follow-up

OBJECTIVES

Antibiotics are used for various reasons before elective joint replacement surgery. The aim of this study was to investigate patients' use of oral antibiotics before joint replacement surgery and how this affects the risk for periprosthetic joint infection (PJI).

METHODS

Patients having a primary hip or knee replacement in a tertiary care hospital between September 2002 and December 2013 were identified (n = 23 171). Information on oral antibiotic courses purchased 90 days preoperatively and patients' chronic diseases was gathered. Patients with a PJI in a 1-year follow-up period were identified. The association between antibiotic use and PJI was examined using a multivariable logistic regression model and propensity score matching.

RESULTS

One hundred and fifty-eight (0.68%) cases of PJI were identified. In total, 4106 (18%) joint replacement operations were preceded by at least one course of antibiotics. The incidence of PJI for patients with preoperative use of oral antibiotics was 0.29% (12/4106), whereas for patients without antibiotic use it was 0.77% (146/19 065). A preoperative antibiotic course was associated with a reduced risk for subsequent PJI in the multivariable model (OR 0.40, 95% CI 0.22-0.73). Similar results were found in the propensity score matched material (OR 0.34, 95% CI 0.18-0.65).

CONCLUSIONS

The use of oral antibiotics before elective joint replacement surgery is common and has a potential effect on the subsequent risk for PJI. Nevertheless, indiscriminate use of antibiotics before elective joint replacement surgery cannot be recommended, even though treatment of active infections remains an important way to prevent surgical site infections.

Decolonization of Staphylococcus aureus in Healthcare: A Dermatology Perspective

The bacterium Staphylococcus aureus is responsible for significant morbidity, mortality, and financial burden in healthcare. It easily colonizes susceptible patients and can cause recurrent infections, especially in populations at risk. In addition to treating sequelae of infections, there is a growing body of literature aimed at decolonizing susceptible patients in order to prevent infection and also to prevent spread. Such strategies are widely employed in surgical, intensive care, and hospitalist fields. Staphylococcus aureus involvement has been implicated in the pathogenesis and persistence of many dermatologic diseases that are treated in the outpatient setting. This review serves to summarize current evidence for the management of Staphylococcus aureus colonized patients, as well as the evidence available for decolonization. We further characterize the role that colonization may play in atopic dermatitis, recurrent infections, hand eczema, cutaneous T-cell lymphoma, and also in surgical infections after Mohs surgery.

Staphylococcus aureus Nasal Colonization: An Update on Mechanisms, Epidemiology, Risk Factors, and Subsequent Infections

Up to 30% of the human population are asymptomatically and permanently colonized with nasal Staphylococcus aureus. To successfully colonize human nares, S. aureus needs to establish solid interactions with human nasal epithelial cells and overcome host defense mechanisms. However, some factors like bacterial interactions in the human nose can influence S. aureus colonization and sometimes prevent colonization. On the other hand, certain host characteristics and environmental factors can predispose to colonization. Nasal colonization can cause opportunistic and sometimes life-threatening infections such as surgical site infections or other infections in non-surgical patients that increase morbidity, mortality as well as healthcare costs.

Prevalence and molecular characterization of Staphylococcus aureus from human stool samples

Background

To determine the prevalence of intestinal S. aureus colonization of patients at a large teaching hospital and determine the molecular characteristics of the identified strains. The second objective of this research was to determine risk factors associated with S. aureus intestinal colonization.

Methods

A cross-sectional study of 781 specimens from inpatients and outpatients at the University of Iowa Hospitals and Clinics Clinical Microbiology Laboratory was conducted. S. aureus was identified using traditional culture methodologies. Methicillin-resistance was determined via PCR of the mecA gene. PVL PCR, spa typing, and antimicrobial sensitivity testing were also done. A nested case-control study was done on a subset of patients with all colonized patients defined as cases and non-colonized controls. Medical record abstractions were done to identify risk factors for intestinal colonization in the nested study.

Results

Out of 625 patients included in the final study, 58 were positive for S. aureus (9.3%). One isolate was positive for the PVL gene. A high number of isolates were resistant to multiple antibiotics including oxacillin (43.1%), erythromycin (51.7%), and levofloxacin (41.4%). All isolates were susceptible to vancomycin, daptomycin, linezolid, and quinupristin-dalfopristin. In the nested study, having a disease or condition of the gastrointestinal tract significantly increased the odds of intestinal colonization (OR: 1.96, 95% CI: 1.04–3.7; aOR: 13.9, 95% CI: 1.67–115.7). No other variables were significantly associated with increased odds of colonization.

Conclusions

S. aureus was identified from the stool of patients at the University of Iowa Hospitals and Clinics, with a large number of those isolates being resistant to antibiotics and may serve a reservoir for subsequent infections as well as asymptomatic transmission.

Epidemiology and clinical relevance of Staphylococcus aureus intestinal carriage: a systematic review and meta-analysis

INTRODUCTION

Recent data highlight the importance of screening more than one site for improving the detection of S. aureus colonization. Intestinal carriage is frequently under-investigated and its clinical impact ought to be defined a better way. Areas covered: This review and meta-analysis provide an updated overview of prevalence, characteristics and clinical significance of S. aureus intestinal carriage in different populations, both for methicillin-susceptible and -resistant S. aureus strains. Expert commentary: Intestinal S. aureus carriage is documented with higher prevalence in children and in patients with S. aureus skin and soft tissue infections. This site of colonization was shown to be associated with a high risk of dissemination in the environment and with S. aureus infection. Intestinal carriage is frequently retrieved in nasal carriers, reflecting probably an association with a high bacterial load. Exclusive intestinal carriage present in one third of intestinal carriers can be associated with infection. Comparative genotyping analysis of different strains from nasal and extra-nasal sites of carriage, including the intestinal ones, in the same individuals, would allow a better comprehension of the pathophysiology of S. aureus endogenous infection. It could also permit to improve the prevention of these infections by decolonization of sites implicated in infection genesis.

Top 10 Myths Regarding the Diagnosis and Treatment of Cellulitis

BACKGROUND

Cellulitis is commonly treated in the emergency department (ED). Patients who present with cellulitis incur significant health care costs and may be overtreated with antibiotics. The accurate diagnosis and treatment of cellulitis plays an important role in cost-effective, high-quality medical care, as well as appropriate antibiotic utilization.

OBJECTIVE

We aim to describe common fallacies regarding cellulitis. We present 10 myths that result in misdiagnosis, overtreatment, or inappropriate empiric management of cellulitis. Clinical presentation, including swelling and redness, is explored in depth, along with incidence of community-acquired methicillin-resistance Staphylococcus aureus, management of tick bites, and effective antibiotic therapy for cellulitis.

DISCUSSION

Patients are often treated for cellulitis unnecessarily or inappropriately. Awareness of these myths will help guide providers in clinical decision making in order to effectively tailor treatment for these infections.

CONCLUSIONS

Cellulitis is not as simple as it might seem, and is commonly misdiagnosed in the ED. Noninfectious causes of local symptoms, including lymphedema, venous stasis, and deep vein thrombosis need to be considered. Cellulitis should be treated with empiric antimicrobial therapy based on patient risk factors and regional susceptibility patterns. This review will assist providers in managing cellulitis and avoiding treatment errors that lead to high costs, unwanted side effects for patients, and overuse of antibiotics.

Current methodologies on genotyping for nosocomial pathogen methicillin-resistant Staphylococcus aureus (MRSA)

Methicillin-resistant Staphylococcus aureus (MRSA) is a common pathogen in hospitals and the community. As the rapid spread and wide distribution of antimicrobial resistance (such as MRSA), treatment for infectious diseases caused by microorganisms has become a vital threat. Thus, early identification and genotyping are essential for further therapeutic treatment and the control of rapid expansion of MRSA. In combination with applications and data feedbacks, this review focused on the currently available molecular-based assays on their utility and performance for rapid typing of MRSA, especially on effective molecular-based methods. Besides, a common mobile element SCCmec and prevalence of HA-MRSA, LA-MRSA and CA-MRSA were introduced in this review in order to provide a more complete profile of MRSA.

Screening for Methicillin-resistant Staphylococcus aureus in a residence home for elderly in Germany

BACKGROUND

Since many hospitals report high MRSA colonization rates among elderly patients, and because it has been shown that S. aureus colonization increases with advancing age, there are concerns about the introduction of MRSA into nursing homes by MRSA positive patients discharged from hospital. So far, admission screening and subsequent longitudinal screening in residence homes or screening at time of hospital discharge is not established on a regular base. On the other hand, MRSA is acquired frequently during hospital stay. Therefore, the MRSA status of residents remains unclear at the time of re-admission to the residence home. This study was conducted to evaluate the rate of nasal MRSA carriage among residents and nursing staffs of 2 nursing homes for the elderly, the potential acquisition of MRSA during a hospital stay and the feasibility to perform direct screening tests in nursing homes for elderly.

METHODS

In a study period of 5 months, possibility of active PCR-based screening for MRSA has been tested within 2 residence homes for the elderly, with the obligation to avoid inconvenience to the daily working time and working schedule. Residents and staff members were included in the study and positive test results were confirmed with MRSA culture.

RESULTS

Feasibility of active on site screening in a residence home for the elderly using a rapid PCR method has been confirmed. 154 of 156 residents participated on baseline testing for all current and new admitted residents. In 9 participating residents with former unknown status, nasal carriage with MRSA was confirmed (5.8%). Among 32 documented and eligible movements between the nursing home and the hospital, MRSA could be confirmed after return to the residence home in 2 cases (6.3%). MRSA could also be detected in 1 of 14 participating nursing staff (7.1%).

CONCLUSION

Prevalence of MRSA was in a range that has been observed for nursing homes in Germany in previous studies. Residents can acquire MRSA during a hospital stay so that further spread after re-admission into the nursing home cannot be excluded. This study shows that easy to perform direct screening tests in outpatient facilities for nursing of the elderly are promising tools as part of potential new strategies for transmission and infection control in such facilities. Additional studies are needed to investigate if screening followed by interventional hygiene measures can reduce MRSA transmission and infection in such facilities.

Prevalence of and Factors Associated With Multidrug Resistant Organism (MDRO) Colonization in 3 Nursing Homes

Nursing home residents are at risk for acquiring and transmitting MDROs. A serial point-prevalence study of 605 residents in 3 facilities using random sampling found MDRO colonization in 45% of residents: methicillin-resistant Staphylococcus aureus (MRSA, 26%); extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL, 17%); vancomycin-resistant Enterococcus spp. (VRE, 16%); carbapenem-resistant Enterobacteriaceae (CRE, 1%). MDRO colonization was associated with history of MDRO, care needs, incontinence, and catheters. Infect Control Hosp Epidemiol 2016;1485-1488.

Management of Adults With Hospital-acquired and Ventilator-associated Pneumonia: 2016 Clinical Practice Guidelines by the Infectious Diseases Society of America and the American Thoracic Society

It is important to realize that guidelines cannot always account for individual variation among patients. They are not intended to supplant physician judgment with respect to particular patients or special clinical situations. IDSA considers adherence to these guidelines to be voluntary, with the ultimate determination regarding their application to be made by the physician in the light of each patient's individual circumstances.These guidelines are intended for use by healthcare professionals who care for patients at risk for hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP), including specialists in infectious diseases, pulmonary diseases, critical care, and surgeons, anesthesiologists, hospitalists, and any clinicians and healthcare providers caring for hospitalized patients with nosocomial pneumonia. The panel's recommendations for the diagnosis and treatment of HAP and VAP are based upon evidence derived from topic-specific systematic literature reviews.

The evaluation of MRSA surveillance cultures by the number and combinations of anatomical sites

Introduction

The identification of patients infected and/or colonised by methicillin resistant Staphylococcus aureus (MRSA) is necessary for the timely introduction of measures for infection control. We compared the diagnostic efficacy of combinations of MRSA surveillance swabs routinely taken by health institutions in the country.

Methods

All surveillance samples, which were sent for a microbiological analysis to detect MRSA with the culture method in 2014, in the three departments for medical microbiology of the National Laboratory for Health, Environment and Food, were included in this study.

Results

Among 65,251 surveillance cultures from 13,274 persons, 1,233 (2.1%) were positive (490 positive persons). Prevailing positive surveillance cultures were throat swabs (31.3%), followed by nose swab (31.2%), skin swab (18.9%), perineum (16.4%) and wound swabs (1.4%). The contribution of other samples, such as aspirate, urine and excreta, was under 1%. We found no statistically significant differences in the frequency of detection of a positive patient, if the combination of samples NTS (nose, throat, skin) or NTP (nose, throat, perineum) was analysed. However, statistically significant differences were confirmed when any of the anatomic sites would be omitted from the sets of NTP and NTS (chi square; p<0.01). Adding additional samples resulted in only 24 additional positive patients (4.9%).

Conclusions

The results indicate that increasing the number of surveillance cultures above three does not add much to the sensitivity of MRSA surveillance, the exception could be wound. The swabs from the perineum and from the skin are exchangeable.

Strategies to Prevent Methicillin-ResistantStaphylococcus aureusTransmission and Infection in Acute Care Hospitals: 2014 Update

Previously published guidelines are available that provide comprehensive recommendations for detecting and preventing healthcare-associated infections (HAIs). The intent of this document is to highlight practical recommendations in a concise format designed to assist acute care hospitals in implementing and prioritizing their methicillin-resistantStaphylococcus aureus(MRSA) prevention efforts. This document updates “Strategies to Prevent Transmission of Methicillin-ResistantStaphylococcus aureusin Acute Care Hospitals,” published in 2008. This expert guidance document is sponsored by the Society for Healthcare Epidemiology of America (SHEA) and is the product of a collaborative effort led by SHEA, the Infectious Diseases Society of America (IDSA), the American Hospital Association (AHA), the Association for Professionals in Infection Control and Epidemiology (APIC), and The Joint Commission, with major contributions from representatives of a number of organizations and societies with content expertise. The list of endorsing and supporting organizations is presented in the introduction to the 2014 updates.

Antimicrobial resistance acquisition after international travel in U.S. travelers

Background

Prior studies have shown an increase in multidrug-resistant (MDR) E. coli colonization from two percent in U.S.-based to 11 % in deployed, healthy military personnel. It is unclear if colonization with MDR organisms occurs through deployment exposures or risks related to routine overseas travel. This study prospectively evaluates rates and risk factors associated with MDR gram-negative bacterial and methicillin-resistant S. aureus (MRSA) colonization after international travel.

Methods

Participants traveled internationally for five or more days. Pre- and post-travel, colonizing bacteria from oropharyngeal, nares, groin, and peri-rectal (PR) areas were collected using BD CultureSwab™ MaxV(+). Identification and susceptibilities were done utilizing the BD Phoenix™ Automated Microbiology System. Non-MDR pre- and post-travel MDR bacteria within a subject were compared by pulsed-field gel electrophoresis (PFGE). A questionnaire solicited demographics and potential risk factors for MDR acquisition.

Results

Of 58 participants, 41 % were male and median age was 64 years. Pre- and post-travel swabs were obtained a median of ten and seven days before and after travel, respectively. Itineraries included 18 participants traveling to the Caribbean and Central America, 17 to Asia, 16 to Africa, 5 to Europe, 4 to South and North America. Seventeen of 22 travelers used atovaquone/proguanil for malaria prophylaxis. The only MDR organism isolated was extended-spectrum β-lactamase (ESBL)-producing E. coli in five (9 %) participants post-travel (all PR and unrelated by PFGE). There were no statistically significant associations between exposure risks and new ESBL-producing E.coli colonization. Of 36 participants colonized with E. coli pre- and post-travel, new resistance was detected: TMP/SMX in 42 % of isolates (p < 0.01), tetracycline in 44 % (p < 0.01), and ampicillin-sulbactam in 33 % (p = 0.09). No participants were colonized with MRSA pre- or post-travel.

Conclusion

Consistent with prior studies, new antimicrobial resistance was noted in colonizing E. coli after international travel. Nine percent of participants acquired new strains of ESBL-producing E.coli without identified risks.

Methicillin-resistant Staphylococcus aureus multiple sites surveillance: a systemic review of the literature

Purpose

The objective of this study was to evaluate the optimal number of sampling sites for detection of methicillin-resistant Staphylococcus aureus (MRSA) colonization.

Methods

We performed a Medline search from January 1966 to February 2014 for articles that reported the prevalence of MRSA at different body sites. Studies were characterized by study design, country and period of the study, number of patients and/or isolates of MRSA, specimen type, sites of MRSA isolation, study population sampled, diagnostic testing method, and percentage of the MRSA isolates at each site in relation to the total number of sites.

Results

We reviewed 3,211 abstracts and 177 manuscripts, of which 17 met the criteria for analysis (n=52,642 patients). MRSA colonization prevalence varied from 8% to 99% at different body sites. The nasal cavity as a single site had MRSA detection sensitivity of 68% (34%–91%). The throat and nares gave the highest detection rates as single sites. A combination of two swabs improved MRSA detection rates with the best combination being groin/throat (89.6%; 62.5%–100%). A combination of three swab sites improved MRSA detection rate to 94.2% (81%–100%) with the best combination being groin/nose/throat. Certain combinations were associated with low detection rates. MRSA detection rates also varied with different culture methods.

Conclusion

A combination of three swabs from different body sites resulted in the highest detection rate for MRSA colonization. The use of three swab sites would likely improve the recognition and treatment of MRSA colonization, which may in turn reduce infection and transmission of MRSA to other patients.

Current Molecular Epidemiology of Methicillin-Resistant Staphylococcus aureus in Elderly French People: Troublesome Clones on the Horizon

Objective: In 2015, we conducted at 44 healthcare facilities (HCFs) and 21 nursing homes (NHs) a 3-month bloodstream infection (BSI) survey, and a 1-day prevalence study to determine the rate of carriage of methicillin-resistant Staphylococcus aureus (MRSA) in 891 patients and 470 residents. We investigated the molecular characteristics of the BSI-associated and colonizing MRSA isolates, and assessed cross-transmission using double-locus sequence typing and pulsed-field gel electrophoresis protocol.

Results: The incidence of MRSA-BSI was 0.040/1000 patient-days (19 cases). The prevalence of MRSA carriage was 4.2% in patients (n = 39) and 8.7% in residents (n = 41) (p < 0.001). BSI-associated and colonizing isolates were similar: none were PVL-positive; 86.9% belonged to clonal complexes 5 and 8; 93.9% were resistant to fluoroquinolones. The qacA/B gene was carried by 15.8% of the BSI-associated isolates [3/3 BSI cases in intensive care units (ICUs)], and 7.7% of the colonizing isolates in HCFs. Probable resident-to-resident transmission was identified in four NHs.

Conclusion: Despite generally reassuring results, we identified two key concerns. First, a worryingly high prevalence of the qacA/B gene in MRSA isolates. Antisepsis measures being crucial to prevent healthcare-associated infections, our findings raise questions about the potential risk associated with chlorhexidine use in qacA/B⁺ MRSA carriers, particularly in ICUs. Second, NHs are a weak link in MRSA control. MRSA spread was not controlled at several NHs; because of their frequent contact with the community, conditions are favorable for these NHs to serve as reservoirs of USA300 clone for local HCFs.

Impact of different diagnostic technologies for MRSA admission screening in hospitals - a decision tree analysis

BACKGROUND

Hospital infections with multiresistant bacteria, e.g., Methicillin-resistant Staphylococcus aureus (MRSA), cause heavy financial burden worldwide. Rapid and precise identification of MRSA carriage in combination with targeted hygienic management are proven to be effective but incur relevant extra costs. Therefore, health care providers have to decide which MRSA screening strategy and which diagnostic technology should be applied according to economic criteria.

AIM

The aim of this study was to determine which MRSA admission screening and infection control management strategy causes the lowest expected cost for a hospital. Focus was set on the Point-of-Care Testing (PoC).

METHODS

A decision tree analytic cost model was developed, primarily based on data from peer-reviewed literature. In addition, univariate sensitivity analyses of the different input parameters were conducted to study the robustness of the results.

FINDINGS

In the basic analysis, risk-based PoC screening showed the highest mean cost savings with 14.98 € per admission in comparison to no screening. Rapid universal screening methods became favorable at high MRSA prevalence, while in situations with low MRSA transmission rates omission of screening may be favorable.

CONCLUSION

Early detection of MRSA by rapid PoC or PCR technologies and consistent implementation of appropriate hygienic measures lead to high economic efficiency of MRSA management. Whether general or targeted screening is more efficient depends mainly on epidemiological and infrastructural parameters.

Cost-benefit analysis from the hospital perspective of universal active screening followed by contact precautions for methicillin-resistant Staphylococcus aureus carriers

OBJECTIVE To explore the economic impact to a hospital of universal methicillin-resistant Staphylococcus aureus (MRSA) screening. METHODS We used a decision tree model to estimate the direct economic impact to an individual hospital of starting universal MRSA screening and contact precautions. Projected costs and benefits were based on literature-derived data. Our model examined outcomes of several strategies including non-nares MRSA screening and comparison of culture versus polymerase chain reaction-based screening. RESULTS Under baseline conditions, the costs of universal MRSA screening and contact precautions outweighed the projected benefits generated by preventing MRSA-related infections, resulting in economic costs of $104,000 per 10,000 admissions (95% CI, $83,000-$126,000). Cost-savings occurred only when the model used estimates at the extremes of our key parameters. Non-nares screening and polymerase chain reaction-based testing, both of which identified more MRSA-colonized persons, resulted in more MRSA infections averted but increased economic costs of the screening program. CONCLUSIONS We found that universal MRSA screening, although providing potential benefit in preventing MRSA infection, is relatively costly and may be economically burdensome for a hospital. Policy makers should consider the economic burden of MRSA screening and contact precautions in relation to other interventions when choosing programs to improve patient safety and outcomes.

Fluoroquinolone Impact on Nasal Methicillin-Resistant and Methicillin-Sensitive Staphylococcus aureus Colonization Durations in Neurologic Long-Term-Care Facilities

Staphylococcus aureus nasal carriage is a risk factor for subsequent infection. Estimates of colonization duration vary widely among studies, and factors influencing the time to loss of colonization, especially the impact of antibiotics, remain unclear. We conducted a prospective study on patients naive for S. aureus colonization in 4 French long-term-care facilities. Data on nasal colonization status and potential factors for loss of colonization were collected weekly. We estimated methicillin-resistant S. aureus (MRSA) and methicillin-sensitive S. aureus (MSSA) colonization durations using the Kaplan-Meier method and investigated factors for loss of colonization using shared-frailty Cox proportional hazards models. A total of 285 S. aureus colonization episodes were identified in 149 patients. The median time to loss of MRSA or MSSA colonization was 3 weeks (95% confidence interval, 2 to 8 weeks) or 2 weeks (95% confidence interval, 2 to 3 weeks), respectively. In multivariable analyses, the methicillin resistance phenotype was not associated with S. aureus colonization duration (P = 0.21); the use of fluoroquinolones (hazard ratio, 3.37; 95% confidence interval, 1.31 to 8.71) and having a wound positive for a nonnasal strain (hazard ratio, 2.17; 95% confidence interval, 1.15 to 4.07) were associated with earlier loss of MSSA colonization, while no factor was associated with loss of MRSA colonization. These results suggest that the methicillin resistance phenotype does not influence the S. aureus colonization duration and that fluoroquinolones are associated with loss of MSSA colonization but not with loss of MRSA colonization.

Comparison of Environmental MRSA Levels on High-Touch Surfaces in Contact Isolation and Noncontact Isolation Patient Rooms

Environmental samples were collected from 100 hospital rooms, 32 noncontact rooms, and 68 contact isolation rooms. We isolated 202 and 1,830 MRSA colonies in noncontact and contact isolation rooms, respectively. The study identified MRSA isolates in hospital rooms of patients without colonization or infection with MRSA.

Infect. Control Hosp. Epidemiol. 2015;36(12):1472–1475

The use of molecular methods for the detection and identification of methicillin-resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) is a major pathogen in many hospitals and long-term care facilities as well as in the community. To limit the spread of MRSA, early detection and proper treatment are essential. Because conventional culture as gold standard is time consuming, new techniques such as PCR-based and hybridization assays have emerged for the rapid detection of MRSA. This review will focus on the currently available molecular-based assays and on their utility and performance for detection of S. aureus, of its virulence factors and of the markers for acquired resistance.

Prevalence of methicillin-resistant Staphylococcus aureus colonization in HIV-infected patients in Barcelona, Spain: a cross-sectional study

Background

Colonization by community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) has been found to be markedly more common in HIV-infected individuals in the USA. Studies evaluating the prevalence MRSA colonization in HIV-infected populations in Europe are scarce. The aim of this study was to investigate the prevalence of MRSA colonization in a cohort of HIV-infected patients in Barcelona, Spain.

Methods

Nasal and pharyngeal S. aureus carriage was assessed in a random sample of 190 patients from an outpatient HIV clinic. Nasal and pharyngeal swab specimens were obtained for staphylococcal culture from 190 and 110 patients respectively. All MRSA isolates were screened for Panton-Valentine leukocidin (PVL) genes by PCR. Molecular characterization of MRSA isolates was performed by multilocus sequence typing. Data related to HIV infection, healthcare exposure, and previously described risk factors for MRSA were collected from medical records and a questionnaire administered to each patient.

Results

The patients’ characteristics were as follows: male, 83 %; median (IQR) age, 45 (39–49) years; intravenous drug users, 39 %; men who have sex with men, 32 %; heterosexual, 26 %; CD4 count, 528/μL (IQR 351–740); on antiretroviral therapy, 96 %; and undetectable plasma viral load, 80 %. Sixty-five patients (34 %) were colonized by S. aureus. MRSA colonization was found in 1 % and 2 % of nasal and pharyngeal samples respectively. No PVL positive MRSA strains were detected and all the MRSA isolates belonged to typical hospital-acquired clones.

Conclusions

Our data suggest that CA-MRSA colonization is not currently a problem in HIV-infected individuals in our area.

Swabbing Surgical Sites Does Not Improve the Detection of Staphylococcus aureus Carriage in High-Risk Surgical Patients

BACKGROUND

A major risk factor for the development of surgical site infections is Staphylococcus aureus carriage. Compared with non-carriers, S. aureus carriers have up to a 14-fold greater risk for post-surgical infections. Pre-operative screening for S. aureus carriage is controversial. Yet, targeted screening in high-risk patients or from clinically relevant sites may be beneficial. We aimed to determine whether S. aureus detection in high-risk surgical patients would be increased by culturing surgical sites, in addition to the nares, vs. nares-only culturing.

METHODS

Adults undergoing pre-operative evaluations in orthopedic and neurosurgical clinics were eligible for participation. For each subject, specimens were collected from the anterior nares and from the proposed surgical site. Samples were inoculated onto methicillin-resistant S. aureus-selective chromogenic agar plates and blood agar plates.

RESULTS

Of 150 subjects, 80 (53.3%) were women and 70 (46.7%) men. The mean age was 61 years and 77/150 (51.3%) had a BMI≥30. Culture results were available for 147/150 subjects. Of the 147 surgical site cultures, 54 (36.7%), 51 (34.7%), and 28 (19.0%) were collected from knee, hip, and lumbar sites, respectively; the remaining 14 (9.5%) were from cervical, thoracic, or infra-clavicular sites. Overall, 35/147 (23.8%) nasal cultures grew S. aureus; 29/147 (19.7%) grew methicillin-susceptible S. aureus (MSSA), and 6/147 (4.1%) grew methicillin-resistant S. aureus (MRSA). Only 2/147 (1.4%) surgical site cultures grew S. aureus; both grew MSSA and MSSA was cultured also from the nasal swabs of these subjects. Using nasal culture+surgical site culture as "true positive," the percentage of additional S. aureus carriers detected by the addition of surgical site screening was zero as compared to nasal screening alone.

CONCLUSIONS

The detection of S. aureus carriage in high-risk surgical patients is not improved by swabbing surgical sites in addition to the nares.

Tolerability of a probiotic in subjects with a history of methicillin-resistant Staphylococcus aureus colonisation

Methicillin-resistant Staphylococcus aureus (MRSA) is a pathogen of major public health importance. Colonisation precedes infection; thus reducing MRSA carriage may be of benefit for reducing infection. Probiotics represent a novel approach to reducing MRSA carriage. We undertook a pilot feasibility randomised controlled trial of the tolerability and acceptability of probiotics for reducing nasal and intestinal carriage of MRSA. In addition, subjects were screened for vancomycin-resistant enterocococci (VRE). Subjects with a history of MRSA were recruited from a large, academic medical center and randomised to take either a placebo or probiotic (Lactobacillus rhamnosus HN001). Subjects returned to the clinic after four weeks for further testing to determine adherence to the probiotic regimen and colonisation of MRSA. 48 subjects were enrolled and randomised. Nearly 25% were transplant recipients and 30% had diabetes. The probiotic was well tolerated in the study population though minor side effects, such as nausea and bloating, were observed. A majority of the subjects randomised to HN001 had good adherence to the regimen. At the four week time point among subjects randomised to the probiotic, MRSA was detected in 67 and 50% of subjects colonised in the nares and the gastrointestinal tract, respectively. Three subjects who initially tested positive for VRE were negative after four weeks of probiotic exposure. Probiotics were well tolerated in our study population of largely immunocompromised subjects with multiple comorbidities. Adherence to the intervention was good. Probiotics should be studied further for their potential to reduce colonisation by multidrug resistant bacteria.

Colonization of epidermal tissue by Staphylococcus aureus produces localized hypoxia and stimulates secretion of antioxidant and caspase-14 proteins

A partial-thickness epidermal explant model was colonized with green fluorescent protein (GFP)-expressing Staphylococcus aureus, and the pattern of S. aureus biofilm growth was characterized using electron and confocal laser scanning microscopy. The oxygen concentration in explants was quantified using microelectrodes. The relative effective diffusivity and porosity of the epidermis were determined using magnetic resonance imaging, while hydrogen peroxide (H2O2) concentration in explant media was measured by using microelectrodes. Secreted proteins were identified and quantified using elevated-energy mass spectrometry (MS(E)). S. aureus biofilm grows predominantly in lipid-rich areas around hair follicles and associated skin folds. Dissolved oxygen was selectively depleted (2- to 3-fold) in these locations, but the relative effective diffusivity and porosity did not change between colonized and control epidermis. Histological analysis revealed keratinocyte damage across all the layers of colonized epidermis after 4 days of culture. The colonized explants released significantly (P < 0.01) more antioxidant proteins of both epidermal and S. aureus origin, consistent with elevated H2O2 concentrations found in the media from the colonized explants (P< 0.001). Caspase-14 was also elevated significantly in the media from the colonized explants. While H2O2 induces primary keratinocyte differentiation, caspase-14 is required for terminal keratinocyte differentiation and desquamation. These results are consistent with a localized biological impact from S. aureus in response to colonization of the skin surface.

Prevalence and risk factors for methicillin-resistant Staphylococcus aureus in an HIV-positive cohort

BACKGROUND

Persons living with HIV (PLWH) are disproportionately burdened with methicillin-resistant Staphylococcus aureus (MRSA). Our objective was to evaluate prevalence and risks for MRSA colonization in PLWH.

METHODS

Adults were recruited from Johns Hopkins University AIDS Service in Baltimore, Maryland. A risk questionnaire and specimen collection from anatomic sites with culture susceptibility and genotyping were completed. Generalized estimating equation modeling identified MRSA colonization risk factors.

RESULTS

Of 500 participants, most were black (69%), on antiretroviral therapy (ART) (87%), with undetectable viral loads (73.4%). Median CD4 count was 487 cells/mm(3) (interquartile range, 316-676.5 cells/mm(3)). MRSA prevalence was 15.4%, predominantly from the nares (59.7%). Forty percent were nares negative but were colonized elsewhere. Lower odds for colonization were associated with recent sexual activity (adjusted odds ratio [AOR] = 0.84, P < .001) and ART (AOR = 0.85, P = .011). Increased odds were associated with lower income (<$25,000 vs >$75,000; AOR = 2.68, P < .001), recent hospitalization (AOR = 1.54, P < .001), incarceration (AOR = 1.55, P < .001), use of street drugs (AOR = 1.43, P < .001), and skin abscess (AOR = 1.19, P < .001).

CONCLUSIONS

Even with high MRSA prevalence, the proportion identified through nares surveillance alone was low, indicating the importance of screening multiple anatomic sites. Associations were not found with same-sex coupling or black race. MRSA prevention might be a benefit of ART in PLWH.

Occupational determinants of methicillin-resistant Staphylococcus aureus colonization among healthcare workers: a longitudinal study in a rehabilitation center

BACKGROUND Staphylococcus aureus carriage among healthcare workers (HCWs) is a concern in hospital settings, where it may provide a reservoir for later infections in both patients and staff. Earlier studies have shown that the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) carriage in HCWs is highly variable, depending notably on location, hospital department type, MRSA prevalence among patients, and type of contacts with patients. However, MRSA incidence in HCWs and its occupational determinants have seldom been studied. METHODS A prospective, observational cohort study was conducted between May and October 2009 in a French rehabilitation center hospital. HCWs and patients were screened weekly for S. aureus nasal carriage. Methicillin-susceptible S. aureus and MRSA prevalence and incidence were estimated and factors associated with MRSA acquisition were identified using generalized estimating equation regression methods. RESULTS Among 343 HCWs included in the analysis, the average prevalence was 27% (95% CI, 24%-29%) for methicillin-susceptible S. aureus and 10% (8%-11%) for MRSA. We observed 129 MRSA colonization events. According to the multivariable analysis, high MRSA prevalence level among patients and HCW occupation were significantly associated with MRSA acquisition in HCWs, with assistant nurses being more at risk than nurses (odds ratio, 2.2; 95% CI, 1.4-3.6). CONCLUSIONS Our findings may help further our understanding of the transmission dynamics of MRSA carriage acquisition in HCWs, suggesting that it is notably driven by carriage among patients and by the type of contact with patients.