Objective: To determine the rate of perinatal hepatitis B virus (HBV) transmission in an Australian setting and to identify maternal virological factors associated with highest risk of transmission. Design, participants and setting: A prospective, observational study of perinatal transmission of HBV. Participants were pregnant women attending Sydney South West Area Health Service antenatal clinics who tested positive for hepatitis B surface antigen (HBsAg), and their babies. All babies were routinely offered hepatitis B immunoglobulin (HBIG) and HBV vaccination. Babies positive for HBsAg at 9‐month follow‐up underwent further virological testing, including HBV DNA sequencing. The study was conducted between August 2002 and May 2008. Main outcome measures: HBV DNA levels and demographic characteristics of HBsAg‐positive pregnant women; proportion of their infants with active HBV infection at 9‐month follow‐up; maternal characteristics affecting transmission rate; HBV DNA sequencing of infected infants and their mothers. Results: Of 313 HBsAg‐positive pregnant women, 213 (68%) were HBV DNA‐positive and 92 (29%) were positive for hepatitis B “e” antigen (HBeAg); 138 babies born to HBV DNA‐positive mothers were tested for HBV infection (HBsAg positivity) at about 9 months of age. Four cases of transmission were identified. All four mothers had very high HBV DNA levels (> 108 copies/mL) and were HBeAg‐positive. Three of the four infants were infected with wild‐type HBV strains, with identical maternal/infant isolates. The fourth mother–infant pair had an S gene variant, HBV D144E, which has been previously reported in association with vaccine/HBIG escape. (Unfortunately, HBIG was inadvertently omitted from the immunisation schedule of this infant.) Transmission rates were 4/138 (3%) from HBV DNA‐positive mothers overall, 4/61 (7%) from HBeAg‐positive mothers, and 4/47 (9%) from mothers with very high HBV DNA levels. No transmission was seen in 91 babies of mothers with HBV DNA levels < 108 copies/mL. Conclusion: In this cohort, HBV perinatal transmission was restricted to HBeAg‐positive mothers with very high viral loads.

Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) was evaluated prospectively in a diagnostic laboratory. Nine hundred twenty-seven organisms were tested in triplicate; 2,351/2,781 (85%) species and 2,681/2,781 (96%) genus identifications were correct. Known issues such as the misidentification of alpha-hemolytic streptococci as Streptococcus pneumoniae were easily corrected. Identifications cost AUD$0.45 per isolate and were available in minutes. MALDI-TOF MS is rapid, accurate, and inexpensive.Matrix-assisted laser desorption-ionization time of flight mass spectrometry (MALDI-TOF MS) has been shown to be both accurate in the identification of bacteria (1,8,9) and rapid (5,10,11,13,14), which is of proven benefit to patient care (2, 4). New technology is never able to completely replace conventional methods; rather, these tests form part of the overall diagnostic algorithms. We therefore undertook this prospective study to determine the utility of the MALDI-TOF MS in a routine diagnostic laboratory for bacterial identification.All bacteria isolated within one calendar month from any site or specimen type that would normally undergo identification were tested in parallel with our routine methods and in triplicate (to assess the reproducibility of the results) using the microflex MALDI Biotyper 2.0 (Bruker Daltonics, GmbH, Bremen, Germany) according to the manufacturer's instructions (software version 3.1.1.0). As specified by the manufacturer, identification scores of Ն2 and between 1.7 and 1.9 were required for a reliable identification to the species and genus level, respectively, while identification scores of Ͻ1.7 were considered unreliable. MALDI-TOF MS identifications were compared to identifications by current methods, which included Vitek2 and API identification kits (bioMérieux, Australia) supplemented with conventional biochemical assays as required (e.g., oxidase, catalase). Resolution of discrepancies between results of conventional testing and the MALDI-TOF MS were initially made by repeating the MS test following crude extraction with formic acid using the manufacturer's recommended method. 16S rRNA sequencing was then used to resolve any remaining discrepancies. A result was considered a major error whenever the resolved final genus identification differed from that proposed by MALDI-TOF MS, while a result was considered a minor error when the genus identification was concordant but the species name was incorrect.Nine hundred twenty-seven organisms were included in the study (Table 1) and tested in triplicate on the MALDI Biotyper (n ϭ 2,781). Of these, 84.5% (2,351/2,781) and 96.4% (2,681/ 2,781) were correct to the species and genus level, respectively. In the 330 tests with identification scores between 1.7 and 1.9, the identification was correct to the species level in all cases. Furthermore, additional MS testing following crude extraction failed to produce an identification different from that originally proposed, although the identification score of...

Unlike vancomycin trough concentrations, data on the utility of vancomycin pharmacokinetic (PK) parameters, namely, the area under the concentrationtime curve from 0 to 24 h (AUC 0 -24 ), in predicting acute kidney injury (AKI) are limited. Our aim was to investigate this relationship in patients receiving vancomycin therapy for methicillin-resistant Staphylococcus aureus bacteremia (MRSA-B). A singlecenter retrospective observational cohort study involving 127 consecutive MRSA-B patients was conducted to examine the incidence of AKI (defined as serum creatinine of Ն0.5 mg/liter and a 50% increase from baseline) and vancomycin exposure parameters associated with nephrotoxicity. Bayesian estimation was used to predict individual vancomycin AUC 0 -24 . All patients received vancomycin monotherapy for a minimum of 14 days following the diagnosis of MRSA-B. AKI was observed in 15.7% of patients (20/127). Clinical characteristics were similar between patients with and without AKI. At steady state, higher vancomycin trough concentrations were associated with AKI (17.2 mg/liter versus 13.1 mg/liter; P ϭ 0.003). A vancomycin AUC 0 -24 threshold for AKI of Ͼ563 mg · h/liter was detected by classification and regression tree (CART) analysis; patients with exposures above this threshold were significantly more likely to experience AKI than patients with lower vancomycin exposures (40% [8/20] versus 11.2% [12/107]; P ϭ 0.002). This parameter remained an independent predictor of AKI on multivariate logistic regression (odds ratio [OR], 5.07; 95% confidence interval [CI], 1.57 to 16.29; P ϭ 0.006) and was a better predictor of nephrotoxicity than vancomycin trough concentrations. Overall, AKI is associated with higher vancomycin exposure as measured by AUC 0 -24 . These results suggest that individualized patient dosing may be possible with dose modifications directed toward established pharmacodynamic targets while balancing AKI risks.

This study sought to assess the antiviral efficacy of lamivudine (LMV) administered during third trimester to reduce maternal viraemia and to identify the emergence of LMV resistance. A prospective observational analysis was performed on 26 mothers with high viral load (>10⁷ IU/mL). Twenty-one women received LMV (treated group) for an average of 53 days (range 22-88 days), and the remaining five formed the untreated control group. Serum samples from two time points were used to measure HBV DNA levels and antiviral drug resistance. The LMV-treated women achieved a median HBV DNA reduction of 2.6-log10 IU/mL. Although end-of-treatment (EOT) HBV DNA in four (18%) LMV-treated women remained at >10(7) IU/mL (± 0.5 log IU/mL), no mother-to-baby transmission was observed. In contrast, a baby from the untreated mother was HBsAg positive at 9 months postpartum. Four technologies were used for drug resistance testing. Only ultra-deep pyrosequencing (UDPS) was sufficiently sensitive to detect minor viral variants down to <1%. UDPS showed that LMV therapy resulted in increased viral quasispecies diversity and positive selection of HBV variants with reverse transcriptase amino acid substitutions at sites associated with primary LMV resistance (rtM204I/V and rtA181T) in four (19%) women. These viral variants were detected mostly at low frequencies (0.63-5.92%) at EOT, but one LMV-treated mother had an rtA181T variant that increased from 2.2% pretherapy to 25.59% at EOT. This mother was also infected with the vaccine escape variant (sG145R), which was inhibited by LMV treatment. LMV therapy during late pregnancy only reduced maternal viraemia moderately, and drug-resistant viral variants emerged.

Despite the low diagnostic yield, results of 16S rRNA PCR can still have a significant impact on patient management due to rationalization or cessation of the antimicrobial therapy. The yield of 16S rRNA PCR was highest for heart valves.