Sterling, T. R. | Search bioRxiv

bioRxiv2020

ODELAM: Rapid sequence-independent detection of drug resistance in clinical isolates of Mycobacterium tuberculosis

Antimicrobial-resistant Mycobacterium tuberculosis (Mtb) causes over 200,000 deaths each year. Current assays of antimicrobial resistance need knowledge of mutations that confer drug resistance, or long periods of culture time to test growth under drug pressure. We present ODELAM (One-cell Doubling Evaluation of Living Arrays of Mycobacterium), a time-lapse microscopy-based method that observes individual cells growing into microcolonies. ODELAM enables rapid quantitative measures of growth kinetics in as little as 30 hours under a wide variety of environmental conditions. We show the utility of ODELAM by identifying ofloxacin resistance in clinical isolates of Mtb and benchmark its performance with standard MIC assays. In one clinical isolate, ODELAM identified ofloxacin heteroresistance and identifies the presence of drug resistant colony forming units (CFU) at 1 per 1000 CFUs in as little as 48 hours. ODELAM is a powerful new tool that can rapidly evaluate Mtb drug resistance in a laboratory setting.

microbiology↗

bioRxiv2019

Mortality among adults living with HIV treated for tuberculosis based on positive, negative, or no bacteriologic test results for tuberculosis: the IeDEA consortium

BackgroundIn resource-constrained settings, people living with HIV (PLWH) treated for tuberculosis (TB) despite negative bacteriologic tests have a higher mortality than those treated with positive tests. Many PLWH are treated without bacteriologic testing; their mortality compared to those with bacteriologic testing is uncertain.\n\nMethodsWe conducted an observational cohort study among PLWH [≥] 15 years of age who initiated TB treatment at clinical sites affiliated with four regions of the International epidemiology Databases to Evaluate AIDS (IeDEA) consortium from 2012-2014: Caribbean, Central and South America, and Central, East, and West Africa. The primary exposure of interest was the TB bacteriologic test status at TB treatment initiation: positive, negative, or no test result. The hazard for death in the 12 months following TB treatment initiation was estimated using the Cox proportional hazard model, adjusted for patient- and site-level factors. Missing covariates were multiply imputed.\n\nResultsAmong 2,091 PLWH included, the median age at TB treatment initiation was 36 years, 44% were female, 53% had CD4 counts [≤] 200 cells/mm3, and 52% were on antiretroviral treatment (ART). Compared to patients with positive bacteriologic tests, the adjusted hazard for death was higher among patients with no test results (HR 1.56, 95% CI 1.08-2.26) but not different than those with negative tests (HR 1.28, 95% CI 0.91-1.81). Older age was also associated with a higher hazard for death, while being on ART, having a higher CD4 count, West Africa region, and tertiary facility level were associated with lower hazards for death.\n\nConclusionPLWH treated for TB with no bacteriologic test results were more likely to die than those treated with positive tests, underscoring the importance of TB bacteriologic diagnosis in resource-constrained settings. Research is needed to understand the causes of death among PLWH treated for TB in the absence of positive bacteriologic tests.

epidemiology↗