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Fosfomycin is a broad-spectrum antibiotic that targets UDP-Nacetylglucosamine enolpyruvyl transferase (MurA), an important enzyme in the early stages of peptidoglycan biosynthesis. In Escherichia coli, fosfomycin resistance can occur through the presence of fos genes (typically fosA3) which encode fosfomycininactivating enzymes (FosA, FosC2), or by mutations in proteins important for the uptake of fosfomycin (CyaA, GlpT, PtsI, UhpA, UhpT) or for its action (MurA)

Background Passive immunisation is an important means of preventing hepatitis A in the most vulnerable populations in the event they are exposed. Trends in hepatitis A seroprevalence may impact on the production of effective immunoglobulin products for passive immunisation. Methods The seroprevalence of hepatitis A antibodies in blood donors in capital cities around Australia was measured using a commercial ELISA. Hepatitis A antibodies were quantified using the same commercial kit in a random sample of those who were seropositive. Results An estimated 51% (95% CI 48–54%) of Australian blood donors were seropositive for hepatitis A. Rates varied across the country and increased with age. The geometric mean titre (GMT) of those who were seropositive among our sample was 1246.8 mIU/mL (geometric standard deviation 11.8 mIU/mL) and increased with age. Conclusion Comparison with published data supported an increase in seroprevalence in younger age groups. The seeming increase in seroprevalence among donors is encouraging regarding Australia's ability to maintain immunoglobulin sufficiency. However, the overall GMT of hepatitis A antibodies in donations may be prone to decrease as current donor cohorts age.

Staphylococcus aureus is a major human pathogen, causing disease in both community and healthcare settings. Over the past two decades, the epidemiology of S. aureus disease has changed dramatically, with the emergence and spread of community-associated methicillin-resistant S. aureus clones. This epidemiological shift, coupled with the association between delayed antimicrobial therapy and increased mortality in S. aureus bacteraemia, has greatly facilitated advances in the rapid molecular diagnosis of S. aureus. Rapid molecular testing for S. aureus can greatly reduce laboratory turnaround time, and in some circumstances, may lead to improved clinical outcomes. In addition, advances in DNA sequencing technology and bioinformatic analysis have shed new lights on the molecular epidemiology and transmission dynamics of S. aureus. In this context, we provide an overview of the key advances in the molecular diagnosis and typing of S. aureus, with a particular focus on the clinical impact and utility of genomic technologies.

Infection with meticillin-resistant Staphylococcus aureus (MRSA) continues to have significant morbidity and mortality. Vancomycin, which has been the mainstay of treatment of invasive MRSA infections, has several drawbacks related to its pharmacological properties as well as varying degrees of emerging resistance. These resistant subpopulations are difficult to detect, making therapy with vancomycin less reliable. The newer agents such as linezolid, daptomycin, ceftaroline, and the newer glycopeptides telavancin and oritavancin are useful alternatives that could potentially replace vancomycin in the treatment of certain conditions. By summarising the discussions that took place at the III MRSA Consensus Conference in relation to the current place of vancomycin in therapy and the potential of the newer agents to replace vancomycin, this review focuses on the challenges faced by the laboratory and by clinicians in the diagnosis and treatment of MRSA infections.

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) infections are emerging in southeast Queensland, Australia, but the incidence of carriage of CA-MRSA strains is unknown. The aim of this study was to assess the nasal carriage rate of S. aureus, including CA-MRSA strains, in the general adult population of southeast Queensland. 396 patients presenting to general practices in two Brisbane suburbs and 303 volunteers randomly selected from the electoral rolls in the same suburbs completed a medical questionnaire and had nasal swabs performed for S. aureus. All isolates of S. aureus underwent antibiotic susceptibility testing and single-nucleotide polymorphism (SNP) and binary typing, including determination of Panton–Valentine leukocidin (PVL). The nasal carriage rate of methicillin-susceptible S. aureus (MSSA) was 202/699 (28%), a rate similar to that found in other community-based nasal carriage studies. According to multivariate analysis, nasal carriage of S. aureus was associated with male sex, young adult age group and Caucasian ethnicity. Only two study isolates (one MSSA and one CA-MRSA) carried PVL. The nasal carriage rate of MRSA was low, at 5/699 (0.7%), and only two study participants (0.3%) had CA-MRSA strains. CA-MRSA is an emerging cause of infection in southeast Queensland, but as yet the incidence of carriage of CA-MRSA in the general community is low.

The epidemiology of meticillin-resistant S. aureus (MRSA) infection has changed remarkably in recent years with the appearance of new MRSA strains causing infections in the community. These strains have now begun to cause healthcare-associated infections. The ability to track such changes is necessary to guide clinical and public health action. Here we report passive surveillance of all public laboratory susceptibility data in Queensland to track changes in MRSA phenotypes corresponding to the major epidemic strains from 2000 to 2006. The inpatient rate of MRSA isolation from pus, tissue and fluid (PTF) and blood culture (BC) specimens declined by 26% and 35%, respectively. The rate of isolation of the AUS-2/3-like phenotype (corresponding to ST239-MRSA-III) decreased from 651 to 242 isolates per million accrued patient days in inpatient PTF and BC, whereas that for non-multiresistant MRSA (nmMRSA, corresponding to community MRSA strains) increased from 71 to 315. The overall outpatient rate of MRSA isolation from PTF and BC increased by 224% and 31%, respectively. The rate of AUS-2/3-like isolates in outpatient PTF decreased from 131 to 60 per million outpatient occasions of service while the nmMRSA rate increased from 52 to 490. Surveillance of phenotypes derived from routine susceptibility data is a useful tool for tracking changes in the epidemiology of MRSA over large geographical regions.

The aim of this study was to assess the discriminatory power and potential turn around time (TAT) of a PCR-based method for the detection of methicillin-resistant Staphylococcus aureus (MRSA) from screening swabs.Screening swabs were examined using the current laboratory protocol of direct culture on mannitol salt agar supplemented with oxacillin (MSAO-direct). The PCR method involved pre-incubation in broth for 4 hours followed by a multiplex PCR with primers directed to mecA and nuc genes of MRSA. The reference standard was determined by pre-incubation in broth for 4 hours followed by culture on MSAO (MSAO-broth).A total of 256 swabs was analysed. The rates of detection of MRSA using MSAO-direct, MSAO-broth and PCR were 10.2, 13.3 and 10.2%, respectively. For PCR, the sensitivity, specificity, positive predictive value and negative predictive values were 66.7% (95%CI 51.9-83.3%), 98.6% (95%CI 97.1-100%), 84.6% (95%CI 76.2-100%) and 95.2% (95%CI 92.4-98.0%), respectively, and these results were almost identical to those obtained from MSAO-direct. The agreement between MSAO-direct and PCR was 61.5% (95%CI 42.8-80.2%) for positive results, 95.6% (95%CI 93.0-98.2%) for negative results and overall was 92.2% (95%CI 88.9-95.5%).(1) The discriminatory power of PCR and MSAO-direct is similar but the level of agreement, especially for true positive results, is low. (2) The potential TAT for the PCR method provides a marked advantage over conventional methods. (3) Further modifications to the PCR method such as increased broth incubation time, use of selective broth and adaptation to real-time PCR may lead to improvement in sensitivity and TAT.

Objectives: To investigate the incidence and epidemiology of non-multiresistant methicillin-resistant Staphylococcus aureus (nmMRSA) infection in south-east Queensland, Australia.Study design: A retrospective survey was done of hospital records of all patients who had non-multiresistant MRSA isolated at Ipswich Hospital (a 250-bed general hospital, 40 km south-west of Brisbane, Queensland, Australia) between March 2000 and June 2001. Laboratory typing of these isolates was done with antibiogram, pulsed-field gel electrophoresis, bacteriophage typing and coagulase gene typing.Results: There were 44 infections caused by nmMRSA. Seventeen infections (39%) occurred in patients from the south-west Pacific Islands (predominantly Samoa, Tonga and New Zealand). Laboratory typing showed that the isolates in Pacific Islanders were Pacific Island strains, and 16/17 of these infections were community acquired. Twenty-three infections (52%) occurred in Caucasians. Eleven of the isolates from Caucasians (48%) were a new predominantly community-acquired strain that we have termed the ‘R’ pulsotype, nine (39%) were Pacific Island strains, and three (13%) were health care institution-associated strains. Four infections occurred in patients who were not Caucasians or Pacific Islanders. Overall, 34 of all 44 infections (77%) were community' acquired.Conclusions: Non-multiresistant MRSA infection, relatively frequently observed in Pacific Islanders in south-east Queensland, is now a risk for Caucasians as well, and is usually community acquired. Clinicians should consider taking microbiological specimens for culture and antimicrobial susceptibility testing in patients with suspected staphylococcal infections who are not responding to empirical therapy with β-lactam antibiotics.

Australian isolates of vancomycin-resistant enterococci (VRE) have been widely scattered geographically, predominantly polyclonal and of the VanB phenotype. Forty-nine VRE were isolated from 47 patients in our hospital from October 1996 to December 1999. Forty-four of these VRE were Enterococcus faecium with a vanA glycopeptide resistance genotype. Four isolates were pathogenic. Thirty-five VRE were from an outbreak in the Renal and Infectious Diseases Units over a four-month period. Pulsed-field gel electrophoresis (PFGE) demonstrated that 41 of the 49 VRE were indistinguishable or closely related. Enhanced environmental cleaning, strict contact isolation of colonized patients and reducing inpatient admissions terminated the epidemic. Cohorting of methicillin-resistant Staphylococcus aureus (MRSA)-positive patients was restricted because VRE patients occupied the isolation facilities. This resulted in a statistically significant increase in MRSA infections across the hospital. VRE epidemics have the ability to influence the epidemiology of other nosocomial pathogens when infection control resources are exhausted.

SummaryA national collaborative study involving the laboratories of 17 Australian hospitals examined the in vitro activity of loracarbef, cefaclor, cephalexin, amoxycillin and amoxycillin/clavulanate against 2661 recently isolated common bacterial pathogens. Loracarbef was the most active agent against Escherichia coli (MIC90 = 1 mg/l) and had activity comparable to other agents against Klebsiella pneumoniae and Proteus mirabilis. Like the oral cephalosporins, it had no activity against species of Enterobacter and Serratia. β-lactamase-producing Staphylococcus aureus and Haemophilus influenzae were moderately sensitive to loracarbef (MIC90 = 8 mg/l for both species). Streptococcus pneumoniae was moderately sensitive to loracarbef (MIC90 = 2 mg/l) but strains which were insensitive to penicillin were often highly resistant.

SummaryA national study was conducted to determine the in vitro activity of 2 newer macrolides, dirithromycin and erythromycylamine compared with that of erythromycin, tetracycline and penicillin. Nineteen major teaching hospitals participated in the study. Minimal Inhibitory Concentrations (MICs) were determined by agar dilution, mostly using Iso-Sensitest Agar and an inoculum of 104 cells per spot. 2284 clinically significant strains were isolated in late 1991 and early 1992, comprising 1736 Gram-positive cocci, 355 Haemophilus influenzae, 97 Moraxella catarrhalis, 32 Listeria monocytogenes, 25 Neisseria meningitidis and 39 Neisseria gonorrhoeae were tested. The study indicates that dirithromycin and erythromycylamine possess antibacterial activity equivalent to that of erythromycin against most Gram-positive cocci and M. catarrhalis. Strains resistant to erythromycin were also resistant to dirithromycin and to erythromycylamine. Tetracycline was as active as the macrolides against both penicillin-resis...

An outbreak of infection due to Streptococcus zooepidermicus is reported. The index case was a patient who suffered an episode of septicaemia complicated by glomerulonephritis. Two other persons in his family were found to be asymptomatic throat carriers. The source of the outbreak was unpasteurised milk from a house cow on the farm where the family lived. Molecular studies confirmed that the strains isolated from the index case, the other family members and the cow's milk were identical. Although a renal biopsy was not performed, the diagnostic criteria for poststreptococcal glomerulonephritis were satisfied. The organism is an uncommon human pathogen that sometimes causes outbreaks of severe infection which may be associated with glomerulonephritis.

Background The prevalence of carbapenemase producing enterobacteriaceae (CPE), particularly IMP producers (IMP), in Australia is increasing. Optimal methods for detection of IMP CPE are unknown. We compare six phenotypic methods to determine the most sensitive method for the detection of IMP CPE. Methods We tested 25 molecularly confirmed IMP CPE producers, including 16 Enterobacter cloacae , collected from Queensland Health hospitals. The following methods were performed: disc susceptibility testing (DST), minimum inhibitory concentrations (MICs) by E-test, broth microdilution (BMD) and Vitek 2, modified hodge test (MHT) and Carba NP test. Results Meropenem MIC range (MIC 50/90 ) was 0.25->32 (4/16), 0.25-32(2/16), 1->16(>16/>16) for BMD, E-test and Vitek 2, respectively. Seventeen percent of isolates had a Vitek 2 meropenem MIC between 1-2 |xg/mL. Using EUCAST breakpoints, all isolates tested resistant by Ertapenem E-test and all except for one isolate was resistant by ertapenem DST. CLSI breakpoints increased detection of CPE with meropenem and imipenem. Carba NP test and MHT provided positive results for all isolates. Conclusion: Our results indicate that isolates with a Vitek 2 meropenem MIC of ≥1 μg/mL should undergo further phenotypic testing. Ertapenem DST, ertapenem E-test, Carba NP test and MHT are the most sensitive methods for detection of IMP CPE.

Aims This study defines the population of Aeromonas spp. in Queensland and carbapenem resistance due to carbapenemase production, CphA. Phenotypic tests were correlated with the presence of the cphA gene. Methods Isolates from blood (22), wound (46), sterile sites (11), stool (18), eye (2) and sputum (1) were characterised by rpoB and gyrB sequencing. Disc diffusion and meropenem E-test MIC were determined. Carbapenemase production was assessed by Carba NP test and cphA by PCR. Results Isolates identified as A. dhakensis (39), A. veronii (21), A. hydrophila (20), A. caviae (14), A. jandaei (4), A. bestiarum (1), and A. sanarellii (1). Disc diffusion and E-test failed to demonstrate carbapenem resistance. Carba NP test performed with 97.4% sensitivity and 95.7% specificity. The cphA gene was detected in A. veronii (21; 100%), A. hydrophila (18; 90%), A. dhakensis (34; 87.2%), A. jandaei (2; 50%), A. bestiarum (1; 100%) and not A. caviae . Discussion Phylogenetic analysis revealed A. dhakensis caused majority of infection, an unrecognised pathogen in this region. Carbapenem resistance due to cphA was prevalent. The Carba NP was a reliable phenotypic test. Adequate speciation and detection of carbapenem resistance in Aeromonas spp. is essential to guide appropriate antimicrobial therapy.

Aim Australia has a low incidence of hepatitis A virus (HAV), with the majority of cases in travellers. Nonetheless, the sero-prevalence of antibodies against HAV among Victorians has increased over the last two decades, likely to be a result of vaccination and increased travel/immigration. This study measured the prevelance of HAV antibodies in blood donors from around Australia to determine if a similar rate exists in other states. Methods Samples were collected from donors between January and July 2011 from Australian capital cities. All samples ( n = 2109) were tested with a commercially available enzyme immunoassay for total anti-HAV antibody (levels ≥ 20IU/mL were considered sero-positive). Results Anti-HAV antibody was detected in 51.4% (95% CI 49.27-53.53%) of donors. Some variability was observed between cities; the highest rates were seen in Sydney donors (57.33%; 95% CI 51.74-62.93%), while the lowest in donors from Brisbane (43.67%; 95% CI 38.05-49.28%). Not surprisingly, sero-prevelance increased with increasing donor age. Conclusions This study demonstrated that over half of donors tested had anti-HAV antibodies, with relatively high rates in all capital cities. Given increased HAV vaccination rates, measuring naturally-acquired HAV infection in blood donors has become increasingly difficult and a serological test discriminating naturally-occurring from vaccine-induced immunity may be of interest.

Accurate and rapid diagnosis of novel influenza A(H1N1) infection is critical for minimising further spread through timely implementation of antiviral treatment and other public health based measures. In this study we developed two TaqMan-based reverse transcription PCR (RT-PCR) methods for the detection of novel influenza A(H1N1) virus targeting the haemagglutinin and neuraminidase genes. The assays were validated using 152 clinical respiratory samples, including 61 Influenza A positive samples, collected in Queenland, Australia during the years 2008 to 2009 and a further 12 seasonal H1N1 and H3N2 influenza A isolates collected from years 2000 to 2002. A wildtype swine H1N1 isolate was also tested. RNA from an influenza A(H1N1) virus isolate (Auckland, 2009) was used as a positive control. Overall, the results showed that the RT-PCR methods were suitable for sensitive and specific detection of novel influenza A(H1N1) RNA in human samples.

Aim To determine the prevalence of toxic shock gene tst in an Australian Staphylococcus aureus and methicillin-resistant S. aureus (MRSA) cohort collected over the last two decades. Method The identity of 300 S. aureus isolates was confirmed by real-time polymerase chain reaction (PCR) assays for mecA, nuc and 16S rRNA. Isolates were assayed for eight single nucleotide polymorphisms (SNPs) and for five binary genes (pvl, cna, sdrE, pUB110, pT181). SNP profiles are concordant with multilocus sequence typing (MLST) clonal complexes (CCs) and/or sequence types (STs). Two real-time PCR assays were developed for tst, based on primer sequences previously described. Results SNP profiles correlated with 21 CCs/STs. The 90 MRSA isolates correlated with three CCs: CC239, CC1 and CC22. We found 18 tst positive isolates, 3/91 (1989), 6/104 (1996) and 9/105 (2003). Of these, CC30 was predominant. Of 210 methicillin-sensitive S. aureus isolates, 26 were CC1, 24 CC5 and 23 CC78. Conclusions The proportion of tst positive isolates and binary genes including pvl was low, and has not increased significantly. Most tst positive isolates belong to CC30 which accords with overseas publications. In 1989 and 1996 CC239 MRSA (AUS-2/3) was the sole MRSA strain. MRSA decreased significantly in 2003 in spite of the appearance of CC1 MRSA (WA-1) and CC22 MRSA (EMRSA-15).