China has a serious epidemic of drug-resistant tuberculosis. MDR tuberculosis is linked to inadequate treatment in both the public health system and the hospital system, especially tuberculosis hospitals; however, primary transmission accounts for most cases. (Funded by the Chinese Ministry of Health.).
BackgroundThe World Health Organization recommends universal drug susceptibility
testing for Mycobacterium tuberculosis complex to guide
treatment decisions and improve outcomes. We assessed whether DNA sequencing
can accurately predict antibiotic susceptibility profiles for first-line
anti-tuberculosis drugs. MethodsWhole-genome sequences and associated phenotypes to isoniazid, rifampicin,
ethambutol and pyrazinamide were obtained for isolates from 16 countries
across six continents. For each isolate, mutations associated with
drug-resistance and drug-susceptibility were identified across nine genes,
and individual phenotypes were predicted unless mutations of unknown
association were also present. To identify how whole-genome sequencing might
direct first-line drug therapy, complete susceptibility profiles were
predicted. These were predicted to be pan-susceptible if predicted
susceptible to isoniazid and to other drugs, or contained mutations of
unknown association in genes affecting these other drugs. We simulated how
negative predictive value changed with drug-resistance prevalence.Results10,209 isolates were analysed. The greatest proportion of phenotypes were
predicted for rifampicin (9,660/10,130; (95.4%)) and the lowest for
ethambutol (8,794/9,794; (89.8%)). Isoniazid, rifampicin, ethambutol and
pyrazinamide resistance was correctly predicted with 97.1%, 97.5% 94.6% and
91.3% sensitivity, and susceptibility with 99.0%, 98.8%, 93.6% and 96.8%
specificity, respectively. 5,250 (89.5%) drug profiles were correctly
predicted for 5,865/7,516 (78.0%) isolates with complete phenotypic
profiles. Among these, 3,952/4,037 (97.9%) predictions of pan-susceptibility
were correct. The negative predictive value for 97.5% of simulated drug
profiles exceeded 95% where the prevalence of drug-resistance was below
47.0%. ConclusionsPhenotypic testing for first-line drugs can be phased down in favour of DNA
sequencing to guide anti- tuberculosis drug therapy.
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