January 08, 2020
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Lack of clinical response to antibiotics ‘strong predictor’ of TB among adults with HIV

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Failure to respond to antibiotics may serve as a strong indicator of tuberculosis among people living with HIV who have symptoms of the disease, according to findings published in Open Forum Infectious Diseases.

“Limitations of current diagnostics remain a challenge in the fight against tuberculosis,” Tom H. Boyles, MD, of the Department of Medicine at the University of Cape Town, and colleagues wrote. “A ‘trial-of antibiotics' is defined as a course of broad-spectrum antibiotics, with negligible Mycobacterium tuberculosis activity, given to patients suspected of having tuberculosis. Patients with a clinical response to antibiotics, which is not consistently defined, are considered unlikely to have tuberculosis and vice versa.”

The researchers aimed to identify the independent predictors of tuberculosis at the index visit and after a trial of empiric antibiotics among adults with HIV and compatible symptoms who sought clinical care. Boyles and colleagues also aimed to develop multivariable prediction models for TB based on independent predictors identified at the index and return visits.

Boyles and colleagues performed a passive case finding cohort study of 207 adults living with HIV with a positive WHO symptom screen. All participants were treated with antibiotics at their first visit according to the local protocol and were evaluated to determine clinical response. Patients also had sputum tested with Xpert MTB/RIF Ultra. Researchers then studied multivariable prediction models for TB based on one or two visits.

Overall, 75 of the 207 patients (36%) had confirmed tuberculosis, nine (12%) of whom were sputum smear positive and 62 (83%) of whom were Ultra positive. Clinical response to antibiotics after 2 days served as “a good predictor of disease,” according to Boyles and colleagues. A multivariable prediction model based on two visits, without C-reactive protein, had “acceptable discrimination (c-statistic, 0.75) and calibration (goodness of fit test, P = .07). Researchers added that the addition of CRP after antibiotics were given ”improved the model moderately (c-statistic, 0.78),” though CRP at the first visit did not serve as an independent predictor of TB.

“A clinical response to antibiotics is useful for diagnosing tuberculosis in people with HIV who are identified by passive case finding and is a strategy that could be implemented immediately,” the authors concluded. “CRP after antibiotics adds value but is not essential. CRP at index presentation is of limited value in this population.” – by Caitlyn Stulpin

Disclosures: Infectious Disease News could not confirm relevant financial disclosures at the time of publication.