Assessment of messenger RNA (mRNA) of Mycobacterium tuberculosis as a marker of cure in patients with pulmonary tuberculosis.

AIMS: To analyse the performance of RT-qPCR using 85B mRNA in the diagnosis of Mycobacterium tuberculosis infection and in the assessment of the response to treatment for pulmonary tuberculosis (TB). METHODS AND RESULTS: Ninety-eight patients with signs of pulmonary TB were selected: 56 were considered infected with Myco. tuberculosis and they had positive cultures or evident clinical response to anti-TB treatment. Patients with pulmonary tuberculosis were evaluated by culture and RT-qPCR for a 30-day specific treatment. It was found that both tests demonstrated a decline in viable bacilli at 15 and 30 days after the beginning of the therapy in most of the patients. The quantification of the 85B mRNA target was performed in 52 patients who had initially shown positive results by RT-qPCR and who were followed on the days 15 and 30 after the specific treatment. Thus 85B mRNA was detectable in sputum samples in 52 patients with a confirmed diagnosis of pulmonary tuberculosis on day 0. During the specific treatment the 85B mRNA was detectable in 13 patients on day 15 and in only three patients on day 30. CONCLUSIONS: Mycobacterium tuberculosis mRNA in the sputum is a useful prognostic marker and its quantification, an early and reliable indicator for monitoring response to treatment, drug resistance, re-infection and relapse. SIGNIFICANCE AND IMPACT OF THE STUDY: RT-qPCR is a tool that can be used in clinical and therapeutic monitoring as an indicator of bacterial resistance and indicator of the period of transmissibility of Myco. tuberculosis in patients with pulmonary TB undergoing treatment.

Evaluation of a IS6110-Taqman real-time PCR assay to detect Mycobacterium tuberculosis in sputum samples of patients with pulmonary TB.

AIM: Evaluate the IS6110-Taqman system performance in sputum samples from patients with pulmonary tuberculosis from health services in north-eastern Brazil as a diagnostic laboratory tool for pulmonary tuberculosis. METHODS AND RESULTS: 165 sputum samples from respiratory symptomatic patients were evaluated in the IS6110-TaqMan assay: 66 patients with pulmonary tuberculosis and 99 without TB. When the IS6110-TaqMan assay was evaluated using culture and/or clinical response to the specific treatment as the gold standard, IS6110-TaqMan assay obtained a sensitivity of 87.9% and specificity of 98%. The performance of IS6110-TaqMan assay was also evaluated with the sputum smear microscopy, resulting in a sensitivity of 79.7% and specificity 94.8%. CONCLUSIONS: The IS6110-TaqMan was rapid, sensitive and specific for the diagnosis of pulmonary TB. SIGNIFICANCE AND IMPACT OF THE STUDY: IS6110-TaqMan assay is a promising auxiliary tool for the diagnosis of pulmonary TB when used in conjunction with routine laboratory tests, clinical and epidemiological criteria of the patient, thus increasing the sensitivity and specificity of diagnosis.

Impact of chromium on the soil invertebrate model Enchytraeus crypticus (Oligochaeta) in standard reproduction and full life cycle tests.

Chromium (Cr) has many applications in industry and day-to-day life, entering the terrestrial environment mostly from anthropogenic sources. Despite the fact that Cr is essential, it can be harmful in biota at high concentrations. Full life cycle tests (FLCt) are scarce, representing a gap for soil ecotoxicology. Hence, the effects of Cr were studied using the soil organism Enchytraeus crypticus in the 46-day FLCt and the standard 21-day enchytraeid reproduction test (ERT). FLCt hatching (day-11) and time to reach maturity (day 22-25) were the most sensitive endpoints, representing a delay, partly recovered with time. Reproduction was reduced to similar levels in both the ERT and the FLCt (EC50∼320 mg Cr/kg), but survival was more affected in the ERT (LC50 = 377 mg Cr/kg) than in the FLC (LC50 = 467 mg Cr/kg). This could be due to the induction of stress response mechanisms at earlier life stages (cocoons/juveniles), providing protection to toxicity in a later stage (adults). FLCt results provided considerably more details and data points, and the additional endpoints allowed to explain the source of observed effects, e.g. a direct impact on fecundity and not only due to adult mortality. The estimated population growth curves confirmed the significant effect of 320 mg Cr/kg and onwards, reflecting the impact of Cr on both cocoon production and juvenile performance, with follow-up consequences for reproduction. An Adverse Outcome Pathway was drafted. The FLCt design is recommended as an upgrade of the current standard ERT, which could be integrated into the existing OECD ERT test guideline.