To the Editor: Although community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) has been reported, it is not recognised as important in Victoria.1 Also, health-care acquisition of “typical CA-MRSA” strains has been reported, but is uncommon.2 Because of an apparent increase in CA-MRSA at Austin Health (a tertiary referral centre in Melbourne encompassing The Austin Hospital, The Heidelberg Repatriation Hospital and Royal Talbot Rehabilitation Centre), we undertook a retrospective survey of cases to determine the frequency of isolation, and clinical and laboratory features of non-multiresistant MRSA (nmMRSA),1 as a marker for CA-MRSA.

Patients with nmMRSA isolated from blood culture between January 2000 and December 2003 or from any specimen between March 2002 and August 2003 were included. Medical records were reviewed, and the mode of acquisition was defined as described previously.3 All isolates underwent polymerase chain reaction testing for genes encoding Panton–Valentine leukocidin, and pulsed field gel electrophoresis (PFGE).

The frequency of isolation of nmMRSA was also reviewed for the period 1999–2004 at two major hospitals in Victoria — Austin Health and Southern Health.

We identified 53 patients with nmMRSA infection or colonisation (Box). Thirteen cases (25%) were community acquired, including one fatal case of endocarditis, nine cases of soft tissue infection, two of bacteraemia, and one of bone/joint infection. Forty cases were health-care-acquired, including 17 cases of skin or soft tissue infection and seven of bacteraemia. Ten hospital patients had nmMRSA colonisation without infection. Patients with health-care-acquired nmMRSA were commonly in the renal or spinal unit or from nursing homes.

PFGE revealed that the 53 nmMRSA isolates belonged to 18 groups, including six that have been previously described (WA-1 and 2, Queensland, SWP, UK EMRSA-15 and 16) and 12 novel groups (A-L). Health-care-acquired infection or colonisation was documented for all PFGE groups, including “typical CA-MRSA” strains (WA-1, WA-2, Queensland, and SWP). Twelve isolates (23%), including four health-care-acquired isolates, were positive for Panton–Valentine leukocidin (PVL). This is of particular concern given the association of PVL-positive S. aureus strains with severe skin disease, necrotising pneumonia, and high mortality in some studies, and the increased virulence of CA-MRSA compared with typical health-care-acquired multiresistant MRSA.4,5 Ten patients with CA-MRSA (77%) received ineffective antimicrobial therapy in the first 48 hours of treatment, including patients with bacteraemia.

From 1999 to 2004, there was a significant decrease in the total number of MRSA cases per hospital discharge at Austin Health and Southern Health, but the number of nmMRSA cases increased, from 0.6 to 1.1 per 1000 discharges at Austin Health (1999 to 2004; P = 0.004) and from 0.08 to 0.35 per 1000 discharges at Southern Health (2001 to 2004; P < 0.001).

Multiple genotypes of CA-MRSA are increasingly causing community-acquired and, importantly, health-care-acquired infections in Victoria. Clinicians need to be alert to this problem, and further research to understand the epidemiology and risk factors is urgently required to help guide changes in therapy and infection control policy.