Validation of Fourier Transform Infrared Spectroscopy for Serotyping of Streptococcus pneumoniae.

Fourier transform infrared (FT-IR) spectroscopy (IR Biotyper; Bruker) allows highly discriminatory fingerprinting of closely related bacterial strains. In this study, FT-IR spectroscopy-based capsular typing of Streptococcus pneumoniae was validated as a rapid, cost-effective, and medium-throughput alternative to the classical phenotypic techniques. A training set of 233 strains was defined, comprising 34 different serotypes and including all 24 vaccine types (VTs) and 10 non-vaccine types (NVTs). The acquired spectra were used to (i) create a dendrogram where strains clustered together according to their serotypes and (ii) train an artificial neural network (ANN) model to predict unknown pneumococcal serotypes. During validation using 153 additional strains, we reached 98.0% accuracy for determining serotypes represented in the training set. Next, the performance of the IR Biotyper was assessed using 124 strains representing 59 non-training set serotypes. In this setting, 42 of 59 serotypes (71.1%) could be accurately categorized as being non-training set serotypes. Furthermore, it was observed that comparability of spectra was affected by the source of the Columbia medium used to grow the pneumococci and that this complicated the robustness and standardization potential of FT-IR spectroscopy. A rigorous laboratory workflow in combination with specific ANN models that account for environmental noise parameters can be applied to overcome this issue in the near future. The IR Biotyper has the potential to be used as a fast, cost-effective, and accurate phenotypic serotyping tool for S. pneumoniae.

Cofactor F430 as a biomarker for methanogenic activity: application to an anaerobic bioreactor system.

Over the last decades, anaerobic bioreactor technology proved to be a competitive technology for purifying wastewater while producing biogas. Methanogens perform the crucial final step in methane production, and monitoring their activity is of paramount importance for system understanding and management. Cofactor F430 is an essential prosthetic group of the methyl-coenzyme M reductase (MCR) enzyme catalysing this final step. This research investigates whether the quantification of cofactor F430 in bioreactor systems is a viable intermediate-complexity monitoring tool in comparison to the conventional biogas and volatile fatty acid (VFA) concentration follow-up and molecular genetic techniques targeting the mcrA gene encoding the MCR protein or its transcripts. Cofactor F430 was quantified in a lab-scale anaerobic membrane bioreactor (AnMBR) using liquid chromatography. The system was subjected to two organic loading rate shocks, and the F430 content of the sludge was followed up alongside mcrA gene copy and transcript numbers and classical performance monitoring tools. The research showed for the first time the combined mcrA gene transcript and F430 content dynamics in an anaerobic bioreactor system and reveals their significant positive correlation with in situ methane production rate. The main difference between the two monitoring methods relates to the cofactor's slower degradation kinetics. The work introduces the use of cofactor F430 as a biomarker for methanogenic activity and, hence, as a monitoring tool that can be quantified within half a working day, yielding information directly related to in situ methanogenic activity in methanogenic reactors.

Membrane photobioreactors for integrated microalgae cultivation and nutrient remediation of membrane bioreactors effluent.

The feasibility of a new concept of wastewater treatment by combining a membrane bioreactor (MBR) and a microalgae membrane photobioreactor (MPBR) is assessed in this study. In this system, the organic carbon present in wastewater is expected to be fully oxidized in the MBR, while the nutrients are removed via the subsequent MPBR treatment. The effluent of a lab-scale MBR was fed into a PBR and a MPBR which served as growing medium for Chlorella vulgaris. The MPBRs demonstrated their superiority by limiting the algae wash-out, thus increasing the allowable optimum dilution rate (Dopt). At these corresponding Dopt values, 3.5 and 2 times higher biomass concentrations and volumetric productivities respectively were achieved by the MPBR. It is also possible to run the MPBR at still higher biomass concentration, thus enabling a smaller footprint and higher nutrient removal efficiency. However, reduced nutrient removal efficiencies were found to be one possible drawback.

Investigation of notifications of hepatitis C in 1994: the experience of three health departments.

Laboratories must notify health departments of cases of hepatitis C in Queensland, the Northern Territory (NT) and the Australian Capital Territory (ACT). Our objectives were to estimate the minimum proportion of notified cases of hepatitis C that were recent infections and to determine the risk factors for infection of the notified cases. We conducted a retrospective investigation of all eligible notifications received at the health departments in Queensland, the Northern Territory and the Australian Capital Territory. Of the 963 notifications about which information was received, 16 per cent were repeat notifications. These were excluded from further analysis. In Queensland, 7 per cent, and in both NT and ACT, 3 per cent of the notifications were considered to be recent infections. The most common risk factor reported for both recent and all other hepatitis C cases was a history of injecting drug use, although the proportion of cases with that history was different in NT from ACT and Queensland. Cases were tested because of screening programs: for drugs and alcohol, in sexually transmitted diseases clinics and prison; and because of clinical indications such as a risk factor, symptoms, or results of liver function tests. Another common reason for testing was a request from a patient. A significant proportion of recorded notifications was repeat notifications. Most notifications were of patients who had become infected more than 12 months ago and the most common risk factor was injecting drug use. There was not a high proportion of cases with unknown risk factors.

An outbreak of measles in a highly immunised population: immunisation status and vaccine efficacy.

An outbreak of 18 cases of measles in a primary school in the Australian Capital Territory in August and September 1993 provided the opportunity to study measles immunisation status and measles vaccine efficacy. Parents of 384 (78 per cent) of 491 children answered a questionnaire on recent illness consistent with measles and measles immunisation. Parents transcribed details of measles immunisation from the personal health record of the child to the questionnaire. Thirty-three per cent of cases and 3.4 per cent of the other children had not been immunised. Overall, 95 per cent of children had been immunised. The efficacy for all measles vaccines was estimated to be 90 per cent (95 per cent confidence interval (CI) 75 to 96) and for measles-mumps vaccine 87 per cent (CI 70 to 95). All of the immunised cases had received measles-mumps vaccine. There was no increased risk of measles infection in those who had been immunised at under 15 months of age compared with those immunised at 15 months or older, or in those who could not provide a date of immunisation compared with those who could. None of the children who had received two doses of vaccine caught measles. The date of immunisation was provided by 65 per cent of the respondents who said their children had been immunised. Asking parents to provide this date instead of viewing the health record is a less expensive way of assessing immunisation status but this method needs to be evaluated. Measles outbreaks still occur in highly immunised populations when vaccine efficacy appears to be acceptable.

Measles vaccine efficacy study in a Canberra high school: a study following a measles outbreak.

An outbreak of measles which occurred in Canberra between October and December, 1991, was investigated to estimate the public health utility of the vaccine. The measles vaccine efficacy was determined for the 13-15 year old children in a selected high school. During the outbreak, at least 82 Canberra children contracted measles. Teenage males accounted for 56% of total cases, and 22% of cases were confirmed by serology. The vaccine coverage in the high school studied decreased with increasing school years, varying from 85.8% in Grade 8 to 79.2% in Grade 10. The highest attack rate occurred in Grade 10 (66/1000). The vaccine efficacy for age 13-15 was estimated to be 72% (95% Cl, 45-86%) but varied from 67 to 73%. Measles remains a serious disease of childhood in Australia. The elimination of measles is only partly dependent on the vaccine coverage of children. Issues relating to the effectiveness of vaccine are also important. A two dose vaccine strategy with the second dose of measles, mumps, rubella vaccine (MMR), given preferably in the last year of primary school or the first year of high school, is supported by the findings of this study.