Survival time of methicillin-resistant Staphylococcus aureus-free status after institutional clearance.

OBJECTIVE: To determine the durability of methicillin-resistant Staphylococcus aureus (MRSA)-free status after patients are removed from contact precautions and the association of specific clearance policy variables with survival. DESIGN: Retrospective cohort study from October 2007 to April 2013. SETTING: Veteran Affairs Boston Healthcare System. PARTICIPANTS: Patients with a prior history of MRSA who were removed from contact precautions after deemed cleared of their MRSA status by infection prevention. METHODS: Active nasal screening results and clinical data from acute, long-term, and outpatient care facilities were evaluated to determine survival of MRSA-free status in a time-to-event analysis. RESULTS: A total of 351 unique patients were followed for 107,112 patient-days. The median age was 68 years. Overall, 249 (71%) of patients remained MRSA-free, and 102 (29%) reverted to MRSA positive. The median MRSA-free survival was 880 days. Comorbidities, presence of indwelling devices, and the use of systemic antibiotics at the time of clearance screening were not associated with MRSA-free survival. More than 21,000 days of inpatient isolation days were avoided during the study period. CONCLUSIONS: The majority of patients removed from contact precautions remained MRSA-free for more than 2 years. Antibiotic use at the time of clearance was not associated with reductions in MRSA-free survival. These findings can be used to simplify clearance criteria, promote clearance policies, and reduce patient isolation days.

Extranasal methicillin-resistant Staphylococcus aureus colonization at admission to an acute care Veterans Affairs hospital.

OBJECTIVE: To evaluate the prevalence of and risk factors for extranasal methicillin-resistant Staphylococcus aureus (MRSA) colonization and its relationship to nasal colonization among veterans hospitalized for acute care. DESIGN: Prospective observational study. SETTING: Veterans Affairs (VA) acute care hospital in Boston, Massachusetts. PATIENTS: Convenience sample of 150 patients hospitalized within the previous 36 hours and screened for nasal MRSA who were not known to have an active MRSA infection or MRSA isolates recovered from a wound during the past 12 months. METHODS: Potential risk factors for MRSA colonization were assessed, and oropharynx, axilla, hand, perirectal, wound, and catheter insertion site samples were obtained for culture. MRSA was identified in chromogenic agar and confirmed by use of routine culture techniques. Nasal MRSA colonization was detected by means of polymerase chain reaction (PCR). RESULTS: Nasal swab samples analyzed by use of PCR yielded results positive for MRSA in 16 (11%) of 150 patients. Extranasal cultures yielded positive results for 3 (2%) of 134 patients who tested negative for nasal MRSA colonization and for 9 (56%) of 16 patients who tested positive for nasal MRSA colonization (odds ratio [OR], 56.1 [95% confidence interval {CI}, 12.4-254.6]; p < .001). The oropharynx was the most commonly colonized extranasal site (10 patients [7%]). Independent risk factors for extranasal MRSA colonization included nasal MRSA colonization (OR, 66.9 [95% CI, 11.8-379.7]; P < .001) and end-stage hepatic disease (OR, 98.5 [95% CI, 3.1-3,112.4]; P = .01). CONCLUSIONS: Extranasal MRSA colonization is infrequent among veterans admitted for acute care to VA Boston Healthcare System. Extranasal MRSA colonization was strongly associated with nasal MRSA colonization, which suggests that the VA MRSA Prevention Initiative is not missing a large number of MRSA-colonized patients by focusing on nasal-only screening.