SUMMARY Staphylococcus aureus bacteremia (SAB) is an important infection with an incidence rate ranging from 20 to 50 cases/100,000 population per year. Between 10% and 30% of these patients will die from SAB. Comparatively, this accounts for a greater number of deaths than for AIDS, tuberculosis, and viral hepatitis combined. Multiple factors influence outcomes for SAB patients. The most consistent predictor of mortality is age, with older patients being twice as likely to die. Except for the presence of comorbidities, the impacts of other host factors, including gender, ethnicity, socioeconomic status, and immune status, are unclear. Pathogen-host interactions, especially the presence of shock and the source of SAB, are strong predictors of outcomes. Although antibiotic resistance may be associated with increased mortality, questions remain as to whether this reflects pathogen-specific factors or poorer responses to antibiotic therapy, namely, vancomycin. Optimal management relies on starting appropriate antibiotics in a timely fashion, resulting in improved outcomes for certain patient subgroups. The roles of surgery and infectious disease consultations require further study. Although the rate of mortality from SAB is declining, it remains high. Future international collaborative studies are required to tease out the relative contributions of various factors to mortality, which would enable the optimization of SAB management and patient outcomes.

Vancomycin remains a clinically useful antibiotic despite the advent of several alternative drugs. Optimising vancomycin therapy with therapeutic drug monitoring is widely recommended. The aim of therapeutic drug monitoring is to help the clinician to achieve target pharmacodynamic parameters in the case of vancomycin, an area under the concentration time curve/minimum inhibitory concentration ratio of ≥400. Vancomycin monitoring methods can be categorised into four categories: empiric trough concentrations; linear regression analysis (one-compartment model), population methods and Bayesian estimation procedures. Although the empiric trough concentrations and population methods are easy to use and require minimal resources, there are large differences in the published vancomycin model parameters. This demonstrates that there is great variance in pharmacokinetic parameters between the models and a single vancomycin model cannot be applied to all patient populations. The linear regression and Bayesian methods recommended more accurate dosage regimens; however, they require additional resources such as information technology and healthcare personnel with background training in pharmacokinetics. The Bayesian methods offered additional advantages such as calculation of doses based on a single-serum concentration and optimisation of the patient's previous pharmacokinetic data to determine subsequent dosage regimens. Computerised programs, utilising the Bayesian estimation procedures, are able to achieve target concentrations in a greater percentage of patients earlier in the course of therapy than the empiric trough concentrations and population methods. We recommend the use of these programs providing there is appropriate expertise available to make appropriate recommendations.

Human infection with Australian Bat Lyssavirus is extremely rare and has not previously been reported in a child. We describe a fatal case of Australian Bat Lyssavirus in an 8-year-old child, and review the literature pertaining to the diagnosis and management of lyssavirus infection with consideration of its applicability to this emerging strain.

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The Sequenom MassARRAY iPLEX single-nucleotide polymorphism (SNP) typing platform uses matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) coupled with single-base extension PCR for high-throughput multiplex SNP detection. In this study, we investigated the use of iPLEX MassARRAY technology for methicillin-resistant Staphylococcus aureus (MRSA) genotyping. A 16-plex MassARRAY iPLEX GOLD assay (MRSA-iPLEX) was developed that targets a set of informative SNPs and binary genes for MRSA characterization. The method was evaluated with 147 MRSA isolates, and the results were compared with those of an established SYBR Green-based real-time PCR system utilizing the same SNP-binary markers. A total of 2352 markers belonging to 44 SNP-binary profiles were analysed by both real-time PCR and MRSA-iPLEX. With real-time PCR as the reference standard, MRSA-iPLEX correctly assigned 2298 of the 2352 (97.7%) markers. Sequence variation in the MRSA-iPLEX primer targets accounted for the majority of MRSA-iPLEX erroneous results, highlighting the importance of primer target selection. MRSA-iPLEX provided optimal throughput for MRSA genotyping, and was, on a reagent basis, more cost-effective than the real-time PCR methods. The 16-plex MRSA-iPLEX is a suitable alternative to SYBR Green-based real-time PCR typing of major sequence types and clonal complexes of MRSA.

Australian bat lyssavirus (ABLV) infection in humans is rare but fatal, with no proven effective therapy. ABLV infection can be prevented by administration of a post-exposure prophylaxis regimen of human rabies immunoglobulin and rabies vaccine. All Australian bats (flying foxes and microbats) should be considered to be carrying ABLV unless proven otherwise. Any bat-related injury (bite, scratch or mucosal exposure to bat saliva or neural tissue) should be notified immediately to the relevant public health unit - no matter how small the injury or how long ago it occurred. Human-to-human transmission of ABLV has not been reported but is theoretically possible. Standard infection control precautions should be employed when managing patients with suspected or confirmed ABLV infection.

Staphylococcus aureus is the most common cause of skin and soft tissue infections (SSTIs). Such infections have increased in several countries recently and at a time when community-associated methicillin-resistant S. aureus (CA-MRSA) strains have emerged globally. We examined changes in Australian hospitalisations for the treatment of cutaneous abscesses between 1999 and 2008, a period when increased numbers of CA-MRSA infections were being reported. National hospitalisation data for cutaneous abscess treatment (1999-2008) were examined. Hospitalisation numbers were collated and age-specific admission rates calculated and examined for changes over time. Yearly admissions for the treatment of cutaneous abscesses increased by 48%, from 8,849 (1999-2000) to 13,126 (2007-2008). The crude annual hospitalisation rate per 100,000 population rose from 46 to 62 respectively. However, increases in admission rates were limited to the 10 to 54 years age range. Incidence rate ratios (IRRs) for final versus baseline year admission rates for these age groups ranged from 1.36 (95% confidence interval [CI] 1.04-1.78) for those aged 10-14 years to 1.64 (95% CI 1.26-2.12) for those aged 45-49 years; p<0.05. Increases in hospitalisation for cutaneous abscess treatment have occurred in Australia during the last decade. Research into the underlying causes and prevention of these infections is a public health priority.

Community-associated methicillin-resistant Staphylococcus aureus has only emerged recently as a cause of serious ocular infections in several different countries. At a tertiary pediatric hospital in Brisbane, Australia, community-associated methicillin-resistant S. aureus orbital cellulitis was first noted in 2009. Since then, it has caused 4 of 9 such infections.