May 07, 2013
1 min read

CA-MRSA colonization more likely in patients with HIV

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Those with HIV were more likely to be colonized with community-associated methicillin-resistant Staphylococcus aureus than HIV-negative patients, and they were more likely to carry USA300 strains, researchers reported in Clinical Infectious Diseases.

“This study extends prior studies documenting the significant impact CA-MRSA has had on HIV-infected patients,” Kyle Popovich, MD, of Rush University Medical Center in Chicago, told Infectious Disease News. “There has been a sense that CA-MRSA rates have been decreasing in recent years. However, our results show a high burden of CA-MRSA in HIV-infected patients and move us beyond qualitative data to a quantitative understanding of this burden.”

Kyle Popovich, MD 

Kyle Popovich

From March 2011 to April 2012, Popovich and colleagues obtained nasal and extranasal cultures from 745 inpatients, 374 with HIV and 371 without, within 72 hours of hospitalization. Overall, 15.7% of the patients were colonized with CA-MRSA. Among those with HIV, 20% were colonized, and among those without HIV, 11% were colonized.

HIV-infected patients had higher prevalence of nasal, extranasal and exclusive extranasal colonization. For both HIV-infected and HIV-negative patients, the perirectal and inguinal areas were the most frequently sites for extranasal colonization. Predictors of colonization among HIV-infected patients included male sex, younger age and recent incarceration. Among HIV-negative patients, the only risk factor was temporary housing.

USA300 was the most common strain, comprising 73.3% of isolates. HIV infection was a predictor of this strain (OR=3.0; 95% CI, 1.32-6.79), as were male sex, younger age, and current or previous illicit drug use. Among all of the colonized patients who were currently or recently incarcerated, all but one carried USA300.

“We found a high frequency of extranasal colonization, which could complicate inpatient infection control strategies,” Popovich said. “Furthermore, community exposures may be important for CA-MRSA risk. Therefore, infection prevention strategies may need to extend beyond inpatient settings.”

Popovich said it is now important to assess if the higher colonization burden observed among HIV-infected patients is associated with increased transmission and what the relationship is to subsequent infection.

Kyle Popovich, MD, can be reached at Rush University Medical Center, 600 S. Paulina, Suite 143, Chicago, IL 60612; email:

Disclosure: Popovich reports no relevant financial disclosures.