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Issue: November 2017
October 05, 2017
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MRSA recolonization linked to home contamination

Issue: November 2017
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Photo of Meghan Davis
Meghan Davis

SAN DIEGO — Patients who recovered from a community-acquired MRSA infection were four times more likely to be recolonized if their homes were contaminated with MRSA, according to data presented at IDWeek.

“The home environment appears to be a reservoir for MRSA,” Meghan Davis, PhD, DVM, MPH, researcher at the Johns Hopkins Bloomberg School of Public Health, said during a presentation. “Therefore, we need to think about interventions in the home as something that may improve our ability to achieve successful decolonization in the future.”

Davis and colleagues analyzed data from 88 index patients diagnosed with community-acquired MRSA (CA-MRSA) skin and soft tissue infections (SSTIs). During a baseline visit, they sampled eight sites in patients’ homes and their household pets. The researchers then randomly assigned patients and their household members to a 1-week intervention of nasal mupirocin and chlorhexidine body wash decolonization (n = 42 index patients) or to an educational intervention on MRSA decolonization.

At baseline, index patients and household members were three times more likely to be colonized with MRSA if their homes were contaminated with MRSA (OR = 3.87; 95% CI, 1.29-11.57). At the 3-month visit, patients and household members in contaminated homes were five times more likely to have MRSA colonization (OR = 5.25; 95% CI, 1.82-15.2). Patients with pets that carried MRSA had a slightly increased risk for colonization; however, Davis said this finding was not statistically significant. At the same time, the number of pets in the home was associated with increased odds for MRSA colonization among people in the home.

“We found that what I call the “petting zone”—the fur on the top of the head and back—was often MRSA contaminated, so it may be that pets can act as moving pieces of the environment. They aren’t necessarily carriers of MRSA,” she said. “In fact, if you remove pets from a contaminated environment, they often will clear MRSA without treatment.”

The researchers further assessed 53 patients who had successfully cleared their MRSA colonization to explore whether home environment contamination and pet colonization were associated with recolonization or persistent MRSA colonization. In this subgroup of patients, 43% were later recolonized and 9% were persistently colonized. Home MRSA contamination at baseline was associated with a fourfold increased risk for recolonization (HR = 4.3; 94% CI, 1.2-16). Patients with home MRSA contamination who had the same strain of MRSA at the baseline visit and at a later visit were nearly 13 times more likely to be persistently colonized (OR = 12.7; 95% CI, 1.33-122).

Davis noted that recent cleaning efforts did not significantly reduce the presence of MRSA in the home and that surfaces not frequently touched, such as the top of the refrigerator, were slightly more likely to be contaminated with MRSA than high-touch surfaces, such as the refrigerator handle.

“The one exception to this was the pillow of the index patient, Davis said. “If I can give you one take-home message, when you treat people with MRSA, you may want to tell them to clean their sheets and pillowcases a lot.”

Davis concluded that more studies are needed to establish causation. – by Stephanie Viguers

Reference:

Davis M, et al. Abstract 93. Home environmental contamination is associated with community-associated methicillin-resistant Staphylococcus aureus re-colonization in treated patients. Presented at: IDWeek; Oct. 4-8, 2017; San Diego.

Disclosure: The researchers report no relevant financial disclosures.