Community-onset Staphylococcus aureus Surveillance Programme annual report, 2012

In 2012, the Australian Group on Antimicrobial Resistance (AGAR) conducted a community-onset period-prevalence survey of clinical Staphylococcus aureus isolated from hospital outpatients and general practice patients including nursing homes, long term care facilities and hospice patients. Day surgery and dialysis patients were excluded. Twenty-nine medical microbiology laboratories from all state and mainland territories participated. Isolates were tested by Vitek2® (AST-P612 card). Results were compared with previous AGAR community surveys. Nationally, the proportion of S. aureus that were methicillin-resistant S. aureus (MRSA) increased significantly from 11.5% in 2000 to 17.9% in 2012 (P<0.0001). Resistance to the non-ß-lactam antimicrobials varied between regions. No resistance was detected to vancomycin, teicoplanin or linezolid. Resistance in methicillin susceptible S. aureus was rare apart from erythromycin (12.8%) and was absent for vancomycin, teicoplanin, linezolid and daptomycin. The proportion of S. aureus characterised as health care-associated MRSA (HA-MRSA) was 5.1%. Three HA-MRSA clones were characterised, with 72.9% and 26.4% of HA-MRSA classified as ST22-IV [2B] (EMRSA-15) and ST239-III [3A] (Aus-2/3 EMRSA) respectively. Multi-clonal community-associated MRSA (CA-MRSA) accounted for 12.5% of all S. aureus. Regional variation in resistance in MRSA was primarily due to the differential distribution of the 2 major HA-MRSA clones; ST239-III [3A] (Aus-2/3 EMRSA), which is resistant to multiple non-ß-lactam antimicrobials, and ST22-IV [2B] (EMRSA-15), which is resistant to ciprofloxacin and typically erythromycin. Although the majority of CA-MRSA were non-multi-resistant, a significant expansion of Panton-Valentine leukocidin (PVL) positive CA-MRSA clones has occurred nationally. The mean age of patients (31.7 years, 95% CI 28.9–34.5) with a PVL positive CA-MRSA infection was significantly lower (P<0.0001), than the mean age of patients with a PVL negative CA-MRSA infection (55.7 years, 95% CI 50.7–60.6). This shift in the molecular epidemiology of MRSA clones in the Australian community will potentially increase the number of young Australians with skin and soft tissue infections requiring hospitalisation

Prevalence of MRSA strains among Staphylococcus aureus isolated from outpatients, 2006

Biennial community-based Staphylococcus aureus antimicrobial surveillance programs have been performed by the Australian Group for Antimicrobial Resistance (AGAR) since 2000. Over this time the percentage of S. aureus identified as methicillin resistant has increased significantly from 10.3% in 2000 to 16% in 2006. This increase has occurred throughout Australia and has been due to the emergence of community-associated MRSA (CA-MRSA) clones. However, healthcare associated MRSA were still predominant in New South Wales/Australian Capital Territory and Victoria/Tasmania. In the 2006 survey CA-MRSA accounted for 8.8% of community-onset S. aureus infections. Although multiple CA-MRSA clones were characterised, the predominate clone identified was Queensland (Qld) MRSA (ST93-MRSA-IV) a Panton-Valentine leukocidin (PVL) positive MRSA that was first reported in Queensland and northern New South Wales in 2003 but has now spread throughout Australia. Several international PVL-positive CA-MRSA clones were also identified including USA300 MRSA (ST8-MRSA-IV). In addition, PVL was detected in an EMRSA-15 (ST22-MRSA-IV) isolate; a hospital associated MRSA clone that is known to be highly transmissible in the healthcare setting. With the introduction of the international clones and the transmission of Qld MRSA throughout the country, over 50% of CA-MRSA in Australia are now PVL positive. This change in the epidemiology of CA-MRSA in the Australian community will potentially result in an increase in skin and soft tissue infections in young Australians. As infections caused by these strains frequently results in hospitalisation their emergence is a major health concern

Prevalence of MRSA among Staphylococcus aureus isolated from hospital inpatients, 2005: Report from the Australian Group for Antimicrobial Resistance

The Australian Group for Antimicrobial Resistance conducted a survey of the prevalence of antimicrobial resistance in unique clinical isolates of Staphylococcus aureus from patients admitted to hospital for more than 48 hours. Thirty-two laboratories from all states and territories collected 2,908 isolates from 1 May 2005, of which 31.9% were methicillin-resistant Staphylococcus aureus (MRSA). The regional prevalence of MRSA varied significantly (P<0.0001) from 22.5% in Western Australia to 43.4% in New South Wales/Australian Capital Territory. Prevalence of MRSA from individual laboratories varied even more from 4% to 58%. This variation was explained in part by distribution of age with the risk of MRSA significantly (P<0.0001) increasing with age. Other unmeasured factors including hospital activity and infection control practices in the individual institution may have also contributed. Further investigation is warranted as reductions in prevalence would reduce morbidity, mortality and healthcare costs

Australian Group on Antimicrobial Resistance Hospital-onset Staphylococcus aureus Surveillance Programme annual report, 2011

In 2011, the Australian Group on Antimicrobial Resistance (AGAR) conducted a period-prevalence survey of clinical Staphylococcus aureus isolated from hospital inpatients. Twenty-nine microbiology laboratories from all states and mainland territories participated. Specimens were collected more than 48 hours post-admission. Isolates were tested by Vitek2® antimicrobial susceptibility card (AST-P612 card). Nationally, the proportion of S. aureus that were methicillin-resistant S. aureus (MRSA) was 30.3%; ranging from 19.9% in Western Australia to 36.8% in New South Wales/Australian Capital Territory. Resistance to the non-ß-lactam antimicrobials was common except for rifampicin, fusidic acid, high-level mupirocin and daptomycin. No resistance was detected for vancomycin, teicoplanin or linezolid. Antibiotic resistance in methicillin susceptible S. aureus (MSSA) was rare apart from erythromycin (13.2%) and there was no resistance to vancomycin, teicoplanin or linezolid. Inducible clindamycin resistance was the norm for erythromycin resistant, clindamycin intermediate/susceptible S. aureus in Australia with 90.6% of MRSA and 83.1% of MSSA with this phenotype having a positive double disc diffusion test (D-test). The proportion of S. aureus characterised as being healthcare-associated MRSA (HA-MRSA) was 18.2%, ranging from 4.5% in Western Australia to 28.0% in New South Wales/Australian Capital Territory. Four HA-MRSA clones were characterised and 98.8% of HA-MRSA isolates were classified as either ST22-IV [2B] (EMRSA-15) or ST239-III [3A] (Aus-2/3 EMRSA). Multiclonal community-associated MRSA (CA-MRSA) accounted for 11.7% of all S. aureus. In Australia, regional variation in resistance is due to the differential distribution of MRSA clones between regions, particularly for the major HA-MRSA clone, ST239-III [3A] (Aus-2/3 EMRSA), which is resistant to multiple non-ß-lactam antimicrobials

First report of human babesiosis in Australia

We report the first human case of babesiosis in Australia, thought to be locally acquired

Antimicrobial susceptibility of Staphylococcus aureus and molecular epidemiology of meticillin-resistant S. aureus isolated from Australian hospital inpatients: Report from the Australian Group on Antimicrobial Resistance 2011 Staphylococcus aureus Surveillance Programme

The Australian Group on Antimicrobial Resistance (AGAR) performs regular multicentre period prevalence studies to monitor changes in antimicrobial resistance. In 2011, 29 laboratories in Australia participated in the national surveillance of Staphylococcus aureus resistance. The survey only included unique isolates from clinical specimens collected ≥48 h after hospital admission. MRSA accounted for 30.3% of S. aureus isolates. MRSA resistance to ciprofloxacin, erythromycin, tetracycline, trimethoprim/sulfamethoxazole, gentamicin and clindamycin (constitutive resistance) varied considerably between regions. Resistance to non-β-lactam antimicrobials was uncommon in MSSA, with the exception of erythromycin. Regional variation in resistance was due to the differential distribution of MRSA clones between regions. The proportion of S. aureus genetically characterised as healthcare-associated MRSA (HA-MRSA) was significantly lower in this survey (18.2%) compared with the 2005 survey (24.2%) (P < 0.0001). Although four HA-MRSA clones were characterised, 98.8% of HA-MRSA were classified as either ST22-MRSA-IV [2B] (EMRSA-15) or ST239-MRSA-III [3A] (Aus-2/3 EMRSA). Multiclonal community-associated MRSA (CA-MRSA) increased markedly from 6.5% in 2005 to 11.7% of all S. aureus in 2011 (P < 0.0001). Although the proportion of MRSA resistant to non-β-lactam antimicrobials has decreased nationally, the proportion of S. aureus that are MRSA has remained stable. This is primarily due to non-multiresistant CA-MRSA becoming more common in Australian hospitals at the expense of the long-established multiresistant ST239-MRSA-III [3A] (Aus-2/3 EMRSA). Given hospital outbreaks of CA-MRSA are thought to be extremely rare, it is most likely that patients colonised at admission with CA-MRSA have become infected with the colonising strain during their hospital stay