Quantitative T-cell interferon-gamma responses to Mycobacterium tuberculosis-specific antigens in active and latent tuberculosis.

The objective was to compare the quantitative T-cell responses measured by the commercial interferon-gamma (IFNgamma) release assays (IGRAs) in active and latent tuberculosis (TB) states. T-cell responses of culture-proven TB cases were compared with those of contacts with positive IGRA results and tuberculin skin tests >or= 15 mm. T-SPOT.TB results in 270 active TB cases and 183 community contacts showed the median spot-forming cells (SFCs) above negative control/2.5 x 10(5) peripheral blood mononuclear cells to be 27 (-1 to 203) vs 10 (-2 to 174) in response to ESAT-6 (p < 0.001); and 37 (0 to 293) vs 13 (0 to 225) to CFP-10 (p < 0.001). The median IFNgamma levels (antigen minus nil control) as measured by QuantiFERON-TB Gold In-tube in 270 cases and 142 contacts in congregate settings was 2.3 IU/ml (-0.58 to 31.44) vs 1.7 IU/ml (0.35 to 26.51, p = 0.98). Quantitative T-cell responses as measured by the T-SPOT.TB may indicate mycobacterial burden and disease activity, but cannot be used to discriminate active from latent TB.

Laboratory safety aspects of SARS at Biosafety Level 2.

The severe acute respiratory syndrome (SARS)-associated coronavirus causes severe disease, is transmissible to the community and there is no effective prophylaxis or treatment--perhaps fulfilling the criteria for biohazard group 3 or 4. The recommendation to use Biosafety Level (BSL)3 practices within a BSL2 environment appears to have been a practical decision based on available resources; most diagnostic laboratories operate at BSL2. Safety is achieved with controls in administration, engineering and personal protective equipment/behaviour. At the heart of every safety policy is a risk assessment based on the exact manipulations employed. Excessive administrative and engineering controls are less important than the training and personal attitudes, abilities and understanding of the staff. The SARS outbreak focused our attention on the safety aspects of common mundane tasks, such as decapping blood tubes. Laboratories often claim they follow certain practices but casual observation does not always support these claims. Guidelines differed and created uncertainty. This was stressful for laboratory staff held accountable for their implementation. Attempts to categorise risks and their management into neatly wrapped parcels are attractive, but closer inspection reveals a subjective element that allows doubt to creep in with varying interpretations of the literature. Staff most at risk were those handling respiratory samples. Staff receiving samples via pneumatic tubes had least control over their exposure and were potentially exposed to aerosols from leaking samples. Risk assessment remains a balance between cost and benefit.

Prevalence of Candida species, including Candida dubliniensis, in Singapore.

We present data on the prevalence of Candida species isolated from inpatients in three Singapore hospitals and from vaginal samples collected at community clinics. Strikingly, approximately 20% of the isolates from blood and vaginal samples were fluconazole-resistant species. By analyzing species-specific gene sequence signatures, we identified Candida dubliniensis from both groups of patients.