MRSA Transmission Increasing in an Urban Setting

Key Point

Living in public housing and African-American race are among the factors attributed to the increasing risk of community-acquired methicillin-resistant Staphylococcus aureus observed in an urban community.

From January 1, 2000, to August 31, 2005, incidence of skin and soft-tissue community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) infections in patients of John H. Stroger, Jr Hospital of Cook County in Chicago has increased by nearly sevenfold, according to Bala Hota, MD, MPH, and colleagues in the May 28 Archives of Internal Medicine. Specifically, CA-MRSA infections increased from 24.0 cases per 100,000 persons to 164.2 cases per 100,000 persons.

During the six-year surveillance, the researchers identified 971 patients with CA-MRSA (cases) and 1,375 patients (controls) with community-associated methicillin-susceptible S aureus (CA-MSSA). Residence in a particular cluster of five high-rise public housing complexes (compared with not living in public housing) and African-American race (compared with white race) were characteristics that increased risk of CA-MRSA (respective odds ratios [ORs], 1.91 and 2.50), while Hispanic race (OR, 0.61) and older age (OR, 0.89 for each decade increase) appeared to be protective. Although HIV-positive status (OR, 1.45) and incarceration (OR, 1.92) increased risk when analyzed as separate entities, “they exhibited interaction and resulted in decreased risk when both were present [OR, 0.16],” the study authors noted. There was no association found between CA-MRSA risk and overcrowding. CA-MSSA incidence remained stable during the study period.

Furthermore, the researchers speculated whether “the concept of a ‘core group’” may be at play, with the “geographically closed” prison population serving as the core and public housing, among other factors, acting as a bridge for transmission.

“Public housing may also house individuals with severe drug problems and squatters (or nonlease tenants) may transiently reside in nondemolished public housing between episodes of homelessness,” the investigators pointed out. “However, whether and what interactions among these populations have contributed to CA-MRSA dissemination require further study.” Also to be determined is whether prevention strategies targeted toward these settings would be beneficial, they suggested.

—Adriene Marshall

Reference
Hota B, Ellenbogen C, Hayden MK, et al. Community-associated methicillin-resistant Staphylococcus aureus skin and soft tissue infection at a public hospital: do public housing and incarceration amplify transmission? Arch Intern Med. 2007;167(10);1026-1033.
Living in public housing and African-American race are among the factors attributed to the increasing risk of community-associated methicillin-resistant Staphylococcus aureus observed in an urban community.

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