Emergence of community-associated methicillin resistant Staphylococcus aureus in Hawaii, 2001-2003

Abstract

Objectives: We conducted a retrospective study to determine trends and characteristics of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) in Hawaii.

Methods: We reviewed medical records of patients with MRSA infections during July 2001-June 2003 in four healthcare facilities. A case was defined as a patient with MRSA infection (colonization excluded), diagnosed in ambulatory settings or < or = 48 h after hospitalization, without previous MRSA or healthcare risk factors. Pulsed-field gel electrophoresis (PFGE) and typing of resistance and toxin genes was performed in 40 MRSA isolates.

Results: CA-MRSA infections increased from 28 (23% of MRSA infections) to 65 (32%) per quarter over the 2-year period (P<0.05). Pacific islanders accounted for 51% of 389 case-patients, but only 24% of the Hawaii population. In the pediatric hospital, Pacific Islanders represented 76% of 90 case-patients versus 35% of the hospital population. Hospital admission, required for 40% (154/389), was associated with prior antimicrobial treatment (P<0.01). The staphylococcal cassette chromosome mec type IV was detected in 38/40 isolates; 31 isolates carried Panton-Valentine leukocidin genes and 22 belonged to the same staphylococcal lineage.

Conclusions: In Hawaii, prevention strategies for CA-MRSA infections should focus on Pacific Islanders. CA-MRSA infections in Hawaii appear to be related to strains causing disease throughout the United States.