Community-onset methicillin-resistant Staphylococcus aureus bacteremia in Northern Australia

Abstract

Background: Community-onset infections caused by methicillin-resistant Staphylococcus aureus (COMRSA) are being increasingly reported worldwide. Methods: A retrospective study was performed of 14 patients with 15 episodes of COMRSA bacteremia (COMRSAB) admitted to the Royal Darwin Hospital, Northern Territory, Australia from 1998 to 2001. Isolates from COMRSAB episodes underwent extended susceptibility testing and molecular typing by pulsed field gel electrophoresis and allotyping of the staphylococcal cassette chromosome mec (SCC mec) region by polymerase chain reaction. Results: The proportion of community-onset S. aureus bacteremia episodes that were due to COMRSA increased from 9% in 1998 to 20% in 2001. The clinical features of COMRSAB were similar to those seen with methicillin-susceptible strains, including sepsis, endocarditis and metastatic infection. Ineffective empiric antimicrobial therapy was administered in the majority (80%) of episodes. All COMRSAB isolates tested contained allotype IV SCC mec, which is commonly found in community isolates of MRSA and rarely found in isolates from healthcare-associated MRSA infection. Conclusion: The increasing incidence of COMRSAB in our region has resulted in the addition of vancomycin to standard empiric therapy in certain patients with suspected S. aureus bacteremia acquired in the community.