The role of healthcare personnel in the maintenance and spread of methicillin-resistant Staphylococcus aureus

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.

Molecular concordance of methicillin-resistant Staphylococcus aureus isolates from healthcare workers and patients

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) is a significant nosocomial pathogen in the ICU. MRSA contamination of healthcare personnel (HCP) gloves and gowns after providing care to patients with MRSA occurs at a rate of 14%-16% in the ICU setting. Little is known about whether the MRSA isolates identified on HCP gown and gloves following patient care activities are the same as MRSA isolates identified as colonizing or infecting the patient.

METHODS

From a multisite cohort of 388 independent patient MRSA isolates and their corresponding HCP gown and glove isolates, we selected 91 isolates pairs using a probability to proportion size (PPS) sampling method. To determine whether the patient and HCP gown or gloves isolates were genetically similar, we used 5 comparative genomic typing methods: phylogenetic analysis, spa typing, multilocus sequence typing (MLST), large-scale BLAST score ratio (LSBSR), and single-nucleotide variant (SNV) analysis.

RESULTS

We identified that 56 (61.5%) of isolate pairs were genetically similar at least by 4 of the methods. Comparably, the spa typing and the LSBSR analyses revealed that >75% of the examined isolate pairs were concordant, with the thresholds established for each analysis.

CONCLUSIONS

Many of the patient MRSA isolates were genetically similar to those on the HCP gown or gloves following a patient care activity. This finding indicates that the patient is often the primary source of the MRSA isolates transmitted to the HCP, which can potentially be spread to other patients or hospital settings through HCP vectors. These results have important implications because they provide additional evidence for hospitals considering ending the use of contact precautions (gloves and gowns) for MRSA patients.

Dissemination of epidemic ST239/ST241-t037-agrI-SCCmecIII methicillin-resistant Staphylococcus aureus in a Tunisian trauma burn intensive care unit

Methicillin-resistant Staphylococcus aureus (MRSA) is an important pathogen causing health care-infections in the world, especially in burns. The aim of this study was to assess the extent of dissemination of MRSA isolated from burn patients in Burn Intensive Care Unit in Tunisia and to evaluate the frequency of virulence and antibiotics resistance genes. Among the 72 S. aureus isolates analyzed in the study, 54% were MRSA. The majority of MRSA (94.8%) were multidrug resistant and they had a high resistance rates to kanamycin (94.8%), tobramycin (90%), tetracycline (94.8%) and ciprofloxacin and rifampicin (87%, each). The gene aac(6')-Ie-aph(2″)-Ia conferring resistance to kanamycine and tobtamycin were detected in all isolates and the aph(3')-Ia gene conferring resistance to gentamicin were detected in 2.8% of resistant isolates. Tetracycline resistance genes tet(M), tet(K) and tet(L) were detected in 100%, 10.8% and 2.8% of the isolates, respectively. The SCCmec type III and the agr type I were the most predominant (69.2% and 90%, respectively). The 27 SCCmecIII-agrI isolates were clustered into two PFGE types A and B. The two representative isolates of PFGE clusters A and B belonged to ST239-t037 and ST241-t037 respectively. As conclusion, our results showed a high prevalence of MRSA in trauma burn intensive care unit belonging to two multidrug resistant clones ST239/ST241-agrI-t037-SCCmecIII MRSA. We also demonstrated that MRSA was disseminated between burn patients.

Risk factors associated with methicillin-resistant Staphylococcus aureus isolation from serially collected sputum samples of patients hospitalized with pneumonia

INTRODUCTION

Risk factors associated with the new detection of methicillin-resistant Staphylococcus aureus (MRSA) during hospitalization remain unclear. This study aimed to identify risk factors associated with MRSA isolation from the sputum of patients admitted with pneumonia, during their hospitalization.

METHODS

Patients were prospectively enrolled from 2003 to 2012. Sputum samples were collected for bacterial cultures on days 1, 4, 7, 11, and 14 of hospitalization and thereafter. Cases of MRSA first isolated from sputum obtained before day 4 were defined as "carriage on admission." Cases of MRSA first isolated on day 4 and thereafter, were defined as "new detection after admission." Statistical analysis was used to investigate the risk factors associated with MRSA isolation.

RESULTS

MRSA was isolated from 167 of 1,008 patients (carriage: 47; new detection: 120). Multivariate analysis revealed that the risk factors for MRSA carriage were activities of daily living (ADL) disability prior to admission (odds ratio [OR], 2.92; 95% confidence interval [CI], 1.37-6.22) and hospitalization within the previous 90 days (OR, 3.75; 95% CI, 1.90-7.41). ADL disability prior to admission (risk ratio [RR], 1.82; 95% CI, 1.17-2.84) and a high pneumonia severity index score upon admission (RR, 2.20; 95% CI, 1.37-3.65) were risk factors for new detection of MRSA.

CONCLUSIONS

Several risk factors were found to be associated with MRSA carriage and/or its new detection, based on the sputum samples from patients admitted with pneumonia. These factors may be indicators for selective surveillance and the early implementation of infection control measures.

Neutrophil Recruitment to Noninvasive MRSA at the Stratum Corneum of Human Skin Mediates Transient Colonization

Staphylococcus aureus is a leading cause of skin and soft issue infection, but paradoxically, it also transiently, and often harmlessly, colonizes human skin. An obstacle to understanding this contradiction has been a shortage of in vivo models reproducing the unique structure and immunology of human skin. In this work, we developed a humanized model to study how healthy adult human skin responds to colonizing methicillin-resistant S. aureus (MRSA). We demonstrate the importance of the outer stratum corneum as the major site of bacterial colonization and how noninvasive MRSA adhesion to corneocytes induces a local inflammatory response in underlying skin layers. This signaling recruits neutrophils to the skin, where they control bacterial numbers, mediating transiency in colonization. This work highlights the spatiotemporal aspects of human skin colonization and demonstrates a subclinical inflammatory response to noninvasive MRSA that allows human skin to regulate the bacterial population at its outer surface.

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.

Methicillin-resistant Staphylococcus aureus tracking spread among health-care workers and hospitalized patients in critical wards at a university hospital, Tehran, Iran

Health-care workers may serve as a reservoir for dissemination of methicillin-resistant Staphylococcus aureus (MRSA) to patients in hospital settings. The present study aimed to screen MRSA in nasal swabs of health-care workers and clinical specimens from patients and investigate the possible relationship between these isolates at a university hospital in Tehran, Iran. Additionally, we aimed to identify potential risk factors for MRSA colonization in health-care workers. Staphylococcus aureus strains were isolated from health-care workers and inpatients who completed a questionnaire on risk factors. Cefoxitin disc diffusion test was also used for detection of MRSA. Moreover, all of the MRSA isolates were subjected to pulsed-field gel electrophoresis (PFGE). Colonization rate of MRSA among health-care workers was 22.5%. Furthermore, out of 24 S. aureus isolates obtained from patients, nine (37.5%) were MRSA. Regarding risk factors, the prevalence of nasal MRSA carriage among hospital personnel who used masks was significantly lower than in those without masks (p 0.007). Using PFGE, 10 clusters and 14 singletons were identified among the MRSA isolates. In this regard, most of the MRSA isolates recovered from health-care carriers and patients in intensive care wards, especially general intensive care units, were grouped in certain clusters, indicating intra-ward transmission of the mentioned isolates in these restricted areas. We concluded that screening and decolonization of carriers, contact precautions, prudent use of antibiotics and implementation of active surveillance are recommended strategies for the prevention and control of MRSA transmission in hospital settings.

Staff exchange within and between nursing homes in The Netherlands and potential implications for MRSA transmission

A recent countrywide MRSA spa-type 1081 outbreak in The Netherlands predominantly affected nursing homes, generating questions on how infection spreads within and between nursing homes despite a low national prevalence. Since the transfer of residents between nursing homes is uncommon in The Netherlands, we hypothesized that staff exchange plays an important role in transmission. This exploratory study investigated the extent of former (last 2 years) and current staff exchange within and between nursing homes in The Netherlands. We relied on a questionnaire that was targeted towards nursing-home staff members who had contact with residents. We found that 17·9% and 12·4% of the nursing-home staff formerly (last 2 years) or currently worked in other healthcare institutes besides their job in the nursing home through which they were selected to participate in this study. Moreover, 39·7% of study participants worked on more than one ward. Our study shows that, in The Netherlands, nursing-home staff form a substantial number of links between wards within nursing homes and nursing homes are linked to a large network of healthcare institutes through their staff members potentially providing a pathway for MRSA transmission between nursing homes and throughout the country.

Antibiotic resistance

Antimicrobial resistance in bacterial pathogens is a challenge that is associated with high morbidity and mortality. Multidrug resistance patterns in Gram-positive and -negative bacteria are difficult to treat and may even be untreatable with conventional antibiotics. There is currently a shortage of effective therapies, lack of successful prevention measures, and only a few new antibiotics, which require development of novel treatment options and alternative antimicrobial therapies. Biofilms are involved in multidrug resistance and can present challenges for infection control. Virulence, Staphylococcus aureus, Clostridium difficile infection, vancomycin-resistant enterococci, and control in the Emergency Department are also discussed.

Methicillin-resistant Staphylococcus aureus (MRSA) contamination in bedside surfaces of a hospital ward and the potential effectiveness of enhanced disinfection with an antimicrobial polymer surfactant

The aim in this study was to assess the effectiveness of a quaternary ammonium chloride (QAC) surfactant in reducing surface staphylococcal contamination in a routinely operating medical ward occupied by patients who had tested positive for methicillin-resistant Staphylococcus aureus (MRSA). The QAC being tested is an antibacterial film that is sprayed onto a surface and can remain active for up to 8 h. A field experimental study was designed with the QAC plus daily hypochlorite cleaning as the experimental group and hypochlorite cleaning alone as the control group. The method of swabbing on moistened surfaces was used for sampling. It was found that 83% and 77% of the bedside surfaces of MRSA-positive and MRSA-negative patients respectively were contaminated with staphylococci at 08:00 hours, and that the staphylococcal concentrations increased by 80% at 1200 h over a 4-hour period with routine ward and clinical activities. Irrespective of the MRSA status of the patients, high-touch surfaces around the bed-units within the studied medical ward were heavily contaminated (ranged 1 to 276 cfu/cm² amongst the sites with positive culture) with staphylococcal bacteria including MRSA, despite the implementation of daily hypochlorite wiping. However, the contamination rate dropped significantly from 78% to 11% after the application of the QAC polymer. In the experimental group, the mean staphylococcal concentration of bedside surfaces was significantly (p < 0.0001) reduced from 4.4 ± 8.7 cfu/cm² at 08:00 hours to 0.07 ± 0.26 cfu/cm² at 12:00 hours by the QAC polymer. The results of this study support the view that, in addition to hypochlorite wiping, the tested QAC surfactant is a potential environmental decontamination strategy for preventing the transmission of clinically important pathogens in medical wards.

Risk factors for Staphylococcus aureus and methicillin-resistant S aureus colonization among health care workers in pediatrics departments

Risk factors for Staphylococcus aureus and methicillin-resistant S aureus (MRSA) were evaluated for 178 health care workers from a public hospital pediatrics department in Brazil. Colonization rates were 33.1% for S aureus and 5.1% for MRSA. Risk factors for S aureus colonization differed from those for MRSA. Results suggest nurses with prolonged pediatric patient contact in inpatient units are at higher risk for MRSA colonization.

MRSA carriage among healthcare workers in non-outbreak settings in Europe and the United States: a systematic review

Abstarct

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

BACKGROUND

Health care workers (HCWs) play a critical role in prevention of health care-associated infections such as methicillin-resistant Staphylococcus aureus (MRSA), but glove and gown contact precautions and hand hygiene may not be consistently used with vulnerable patients.

METHODS

A cross-sectional survey of MRSA knowledge, attitudes/perceptions, and practices among 276 medical, nursing, allied health, and support services staff at an acute-care hospital in the eastern United States was completed in 2012. Additionally, blinded observations of hand hygiene behaviors of 104 HCWs were conducted.

RESULTS

HCWs strongly agreed that preventive behaviors reduce the spread of MRSA. The vast majority reported that they almost always engage in preventive practices, but observations of hand hygiene found lower rates of adherence among nearly all HCW groups. HCWs who reported greater comfort with telling others to take action to prevent MRSA transmission were significantly more likely to self-report adherence to recommended practices.

CONCLUSIONS

It is important to reduce barriers to adherence with preventive behaviors and to help all HCWs, including support staff who do not have direct patient care responsibilities, to translate knowledge about MRSA transmission prevention methods into consistent adherence of themselves and their coworkers to prevention guidelines.

Determining the Latent Tuberculosis Infection by IFN - γ Elispot Assay in Healthcare Workers From University Hospitals of Shiraz, South West of Iran

Background

Classical screening methods are incapable to properly detect LTBI (Latent TB Infection) and HCWs (Healthcare Workers) are at the high risk of exposure. Only few reports estimated the prevalence of LTBI among Iranian HCWs and they mostly used the TST (Tuberculin Skin Test), rather than assessing the response against TB-specific antigens.

Objectives

The current study aimed to determine the frequency of IFN - γ producing blood cells of microbiology and radiology ward technicians by an in-house IFN - γ ELISPOT assay in the University hospitals of Shiraz University of Medical Sciences (SUMS) against recombinant ESAT - 6 and PPD antigens.

Materials and Methods

89 HCWs from medical laboratory and radiology departments of Shiraz University of Medical Sciences’ hospitals, South of Iran, were screened for LTBI. To achieve the goal, an in-house IFN - γ (Interferon - gamma) ELISPOT (Enzyme Linked ImmunoSpot) assay was used to detect the reactivity against ESAT - 6 (Early Secreted Antigen Target protein - 6) and the PPD (Purified Protein Derivate).

Results

Almost 8% of the personnel showed positive TST (over 10 mm) reaction while 29% of them had considerable T - cell reactivity against PPD in ELISPOT assays. However, the ESAT - 6 reactivity was found only in one case of HCWs. No correlation was found between the patterns of the reactions and the age or the duration of the employment or previous vaccination history of the participants. The ELISPOT results were not correlated with the TST results.

Conclusions

Considering the hindrance of TST, the IFN - γ ESAT - 6 ELISPOT assay, even in forms of in-house tests, could replace traditional methods to properly spot the LTBI among the high risk groups from Iran’s health system.

Clonal distribution and possible microevolution of methicillin-resistant Staphylococcus aureus strains in a teaching hospital in Malaysia

OBJECTIVE

To genotypically characterize methicillin-resistant Staphylococcus aureus (MRSA) strains isolated from medical and surgical wards in Universiti Kebangsaan Malaysia Medical Centre (UKMMC) in 2009.

METHODS

MRSA strains were collected and molecularly typed by pulsed-field gel electrophoresis (PFGE).

RESULTS

PFGE typing on 180 MRSA isolated in UKMMC identified 5 pulsotypes (A-E) and 6 singletons, where pulsotypes B and C were suspected to be divergent clones originating from a single ancestor. This study also showed that most MRSA strains were isolated from swab (119 isolates), followed by blood (22 isolates), tracheal aspirate (11 isolates) and sputum (10 isolates). On the other hand, urine and bone isolates were less, which were 4 and 1 isolates, respectively. The distribution of different pulsotypes of MRSA among wards suggested that MRSA was communicated in surgical and medical wards in UKMMC, with pulsotype B MRSA as the dominant strain. Besides, it was found that most deceased patients were infected by pulsotype B MRSA, however, no particular pulsotype could be associated with patient age, underlying disease, or ward of admittance.

CONCLUSIONS

Five pulsotypes of MRSA and 6 singletons were identified, with pulsotype B MRSA as the endemic strains circulating in these wards, which is useful in establishment of preventive measures against MRSA transmission.

Evaluation of food handler practices and microbiological status of ready-to-eat foods in long-term care facilities in the Andalusia region of Spain

Food safety measures in long-term care facilities (LTCFs) are being improved by the introduction of quality control management systems during food production and by the implementation of good manufacturing practices. This study was conducted in LTCFs (geriatric homes) in Andalusia, Spain, during 2008 and 2009 to evaluate sanitary conditions and the microbiological quality and safety of salads and cooked meat products served. A regulation-based checklist was applied to the evaluated centers. Samples of ready-to-eat foods (n = 60) were examined for mesophilic aerobic bacteria (MAB), total coliforms, coagulase-positive staphylococci (CPS), Escherichia coli, Listeria spp., and Salmonella. In parallel, food contact surfaces (working tables, cutting boards, sinks, and faucets) were swabbed and analyzed for MAB and Enterobacteriaceae. The air quality in processing rooms, near sinks, and in canteens also was measured through an active air sampling method for MAB and Staphyloccocus spp. The results obtained revealed some deficiencies regarding handling practices and sanitary conditions tested (i.e., use and change of gloves, hand washing, and cleanliness of work surfaces). The microbial safety of foods examined indicated the absence of pathogens. Average levels of coagulase-positive staphylococci were below 10² CFU/g, and prevalence of E. coli was 6.3% in samples collected. Surface counts were higher on cutting boards and faucets, indicating insufficient cleanliness procedures. This study provides a descriptive analysis of the sanitary conditions of food service systems in LTCF, and this information can help risk managers to better define control measures needed to prevent foodborne infections.

Methicillin-resistant Staphylococcus aureus in Canada: a historical perspective and lessons learned

The history of methicillin-resistant Staphylococcus aureus (MRSA) in Canada has many similarities to MRSA evolution worldwide, but especially to that in the United States and United Kingdom. Reports of MRSA occurred as early as 1964, and community isolates were cited in the 1970s. Nosocomial outbreaks were becoming common by 1978 and flourished gradually thereafter. Endemic institutional MRSA became predominant in the 1990s, threatening large teaching hospitals in particular. In the last decade, both hospital-acquired and community-acquired MRSA have created major medical problems in Canada. More recently, an epidemic of Canadian community-acquired MRSA-10, has led to heightened public health concerns. Canadian contributions to MRSA science are numerous, with organized surveillance continuing to mature across the nation. A typing system for epidemic clones is now available and is being judiciously applied. Estimated costs for MRSA surveillance, treatment, and control are extraordinary, paralleling the dramatic rise in the number of MRSA isolations. Whereas surveillance continues to form an essential aspect of MRSA management, control, eradication, and overall diminution, MRSA reservoirs deserve much greater attention. Such efforts, however, must be as widely publicized in the community and in patient homes as they are in medical institutions responsible for both acute and long-term care.