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.

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.

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.

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.

To test the feasibility of targeted gown and glove use by healthcare personnel caring for high-risk nursing-home residents to prevent Staphylococcus aureus acquisition in short-stay residents.

Uncontrolled clinical trial.

This study was conducted in 2 community-based nursing homes in Maryland.

The study included 322 residents on mixed short- and long-stay units.

During a 2-month baseline period, all residents had nose and inguinal fold swabs taken to estimate S. aureus acquisition. The intervention was iteratively developed using a participatory human factors engineering approach. During a 2-month intervention period, healthcare personnel wore gowns and gloves for high-risk care activities while caring for residents with wounds or medical devices, and S. aureus acquisition was measured again. Whole-genome sequencing was used to assess whether the acquisition represented resident-to-resident transmission.

Among short-stay residents, the methicillin-resistant S. aureus acquisition rate decreased from 11.9% during the baseline period to 3.6% during the intervention period (odds ratio [OR], 0.28; 95% CI, 0.08–0.92; P = .026). The methicillin-susceptible S. aureus acquisition rate went from 9.1% during the baseline period to 4.0% during the intervention period (OR, 0.41; 95% CI, 0.12–1.42; P = .15). The S. aureus resident-to-resident transmission rate decreased from 5.9% during the baseline period to 0.8% during the intervention period.

Targeted gown and glove use by healthcare personnel for high-risk care activities while caring for residents with wounds or medical devices, regardless of their S. aureus colonization status, is feasible and potentially decreases S. aureus acquisition and transmission in short-stay community-based nursing-home residents.

To define how often methicillin-resistant Staphylococcus aureus (MRSA) is spread from resident to resident in long-term care facilities using whole-genome sequencing

Prospective cohort study

A long-term care facility

Elderly residents in a long-term care facility

Cultures for MRSA were obtained weekly from multiple body sites from residents with known MRSA colonization over 12-week study periods. Simultaneously, cultures to detect MRSA acquisition were obtained weekly from 2 body sites in residents without known MRSA colonization. During the first 12-week cycle on a single unit, we sequenced 8 MRSA isolates per swab for 2 body sites from each of 6 residents. During the second 12-week cycle, we sequenced 30 MRSA isolates from 13 residents with known MRSA colonization and 3 residents who had acquired MRSA colonization.

MRSA isolates from the same swab showed little genetic variation between isolates with the exception of isolates from wounds. The genetic variation of isolates between body sites on an individual was greater than that within a single body site with the exception of 1 sample, which had 2 unrelated strains among the 8 isolates. In the second cycle, 10 of 16 residents colonized with MRSA (63%) shared 1 of 3 closely related strains. Of the 3 residents with newly acquired MRSA, 2 residents harbored isolates that were members of these clusters.

Point prevalence surveys with whole-genome sequencing of MRSA isolates may detect resident-to-resident transmission more accurately than routine surveillance cultures for MRSA in long-term care facilities.

Infect Control Hosp Epidemiol 2016;37:685–691

The anterior nares are the most sensitive single site for detecting methicillin-resistant Staphylococcus aureus (MRSA) colonization. Colonization patterns of USA300 MRSA colonization are unknown.

To assess whether residents of extended care facilities who are colonized with USA300 MRSA have different nares or skin colonization findings, compared with residents who are colonized with non-USA300 MRSA strains.

The study population included residents of 5 extended care units in 3 separate facilities who had a recent history of MRSA colonization. Specimens were obtained weekly for surveillance cultures from the anterior nares, perineum, axilla, and skin breakdown (if present) for 3 weeks. MRSA isolates were categorized as USA300 MRSA or non-USA300 MRSA.

Of the 193 residents who tested positive for MRSA, 165 were colonized in the anterior nares, and 119 were colonized on their skin. Eighty-four percent of USA300 MRSA-colonized residents had anterior nares colonization, compared with 86% of residents colonized with non-USA300 MRSA (P = .80). Sixty-six percent of USA300 MRSA–colonized residents were colonized on the skin, compared with 59% of residents colonized with non-USA300 MRSA (P = .30).

Colonization patterns of USA300 MRSA and non-USA300 MRSA are similar in residents of extended care facilities. Anterior nares cultures will detect most—but not all—people who are colonized with MRSA, regardless of whether it is USA300 or non-USA300 MRSA.