Community Acquisition of Gentamicin-Sensitive Methicillin-Resistant Staphylococcus aureus in Southeast Queensland, Australia

Abstract

Community-acquired methicillin-resistant Staphylococcus aureus (MRSA) susceptible to gentamicin has been reported in a number of countries in the 1990s. To study the acquisition of gentamicin-sensitive MRSA (GS-MRSA) in southeast Queensland and the relatedness of GS-MRSA to other strains of MRSA, 35 cases of infection due to GS-MRSA from October 1997 through September 1998 were examined retrospectively to determine the mode of acquisition and risk factors for MRSA acquisition. Thirty-one isolates from the cases were examined using a variety of methods (antibiotyping, phage typing, pulsed-field gel electrophoresis [PFGE] fingerprinting, and coagulase typing by restriction analysis of PCR products) and were compared with strains of local hospital-acquired gentamicin-resistant MRSA (GR-MRSA) and of Western Australian MRSA (WA-MRSA). Only 6 of 23 cases of community-acquired GS-MRSA had risk factors for MRSA acquisition. Twenty of 21 isolates from cases of community-acquired infection were found to be related by PFGE and coagulase typing and had similar phage typing patterns. Hospital-and nursing home-acquired GS-MRSA strains were genetically and phenotypically diverse. Community-acquired GS-MRSA strains were not related to nosocomial GR-MRSA or WA-MRSA, but phage typing results suggest that they are related to GS-MRSA previously reported in New Zealand.

Diagnosis and management of Staphylococcus aureus infections of the skin and soft tissue

“…48 The emergence of CA-MRSA infections in the eastern cities of Australia occurred in the late 1990s. 49,50 Phage typing of isolates from south-east Queensland suggested that the isolates were related to the WSPP strains seen previously in New Zealand. 50 Skin and soft tissue infections were the main types of infection associated with these strains.…”

“…49,50 Phage typing of isolates from south-east Queensland suggested that the isolates were related to the WSPP strains seen previously in New Zealand. 50 Skin and soft tissue infections were the main types of infection associated with these strains. 49 In common with the New Internal Medicine Journal 2005; 35: S97-S105 Dicloxacillin/flucloxacillin 1-2 g q6h IV 2-3 weeks Patients hypersensitive to penicillin: Cephalothin † or cephazolin † 2 g q6h IV or q8h IM Clindamycin 300 mg -600 mg q6h IV Co-trimoxazole (TMP-SMX) 960 mg q12h IV † Note: between 3% and 8% of patients who are hypersensitive to penicillins will exhibit cross-reactivity with cephalosporins (see review on antibiotics in this issue).…”

Epidemiology, clinical features and management of infections due to community methicillin‐resistant Staphylococcus aureus (cMRSA)

“…A later study from Queensland of gentamicinsusceptible MRSA showed that 23 of 35 patients had community-acquired infections, and 16 of these 23 patients lacked risk factors associated with nosocomial MRSA acquisition. 39 The strains were non-multiresistant, most were fully susceptible to non-β-lactams and closely related to New Zealand WSPP strains, and most patients were Polynesians. Subsequent work from New South Wales showed that WSPP strains were usually associated with skin and soft tissue infections, but that the infections were much more severe than infections with methicillin-susceptible S. aureus (MSSA) or multiresistant MRSA strains and the majority of patients required hospital admission and surgery.…”

“…35 The epidemic was most intense in the Auckland area, and the organisms spread widely, including to Australia. 11,14,20,39 In Australia, they are also known as the South-western Pacific 39 or Oceania strain. 40 Multiple case reports and two small series 3,41 were reported from the USA during this period.…”

“…Virtually all studies reporting clinical manifestations have found that cMRSA infection is most often manifest by skin and soft tissue suppuration. 3,11,14,39,[45][46][47][48] Common presentations A study from New South Wales sought to compare the clinical features of infections with non-multiresistant MRSA, multiresistant MRSA, and methicillinsusceptible S. aureus (MSSA). 14 Compared with the other two groups, patients with non-multiresistant MRSA were younger, more likely to be Polynesian, less likely to have the usual risk factors for MRSA acquisition, more likely to present with boils and abscesses, and more likely to need admission and surgery.…”