Latent TB and depressive symptoms in household contacts of persons with active TB.

BACKGROUND: Depression is common among persons with TB and is associated with poor clinical outcomes. However, little is known about the relationship between latent TB infection (LTBI) and depression. We assessed the association between LTBI and depressive symptoms among household contacts (HHCs) of patients receiving TB treatment.METHODS: We enrolled 1,009 HHCs of 307 patients receiving TB treatment in Lima, Peru, during 2016-2018. At enrollment, HHC LTBI status was assessed using the interferon-gamma release assay (IGRA). Depressive symptoms were assessed at baseline and 12 months later using the Patient Health Questionnaire-9 (PHQ-9) with a cut-off of ≥5. We used logistic regression to estimate the odds ratio (OR) for PHQ-9 ≥5, comparing HHCs with and without baseline LTBI.RESULTS: Among 921 HHCs, 374 (41.0%) had LTBI at baseline, and 69 (12.4%) of 567 HHCs had PHQ-9 ≥5. Compared to HHCs without LTBI at enrollment, those with LTBI had almost two times the odds of PHQ-9 ≥5 at follow-up after controlling for potential confounders (adjusted OR 1.93, 95% CI 1.09-3.39); this association was driven by greater severities of depressive symptoms.CONCLUSION: HHCs with LTBI had increased odds of depressive symptoms 1 year later. This population may benefit from mental health screening and interventions integrated into TB programs.

Culture-negative TB: clinical characteristics, risk factors and treatment outcomes.

BACKGROUND: Although culture remains the standard for TB diagnosis, 15-20% of patients diagnosed and treated for TB are culture-negative. We explored clinical characteristics, risk factors and treatment outcomes for culture-negative TB in a Peruvian cohort.METHODS: We recruited 4,500 index TB patients and 10,160 household contacts in Lima, Peru, and enrolled 692 secondary patients diagnosed with TB during follow-up of household contacts. We analyzed smear and culture status, sociodemographic factors, clinical characteristics and TB treatment outcomes to compare culture-negative and positive patients.RESULTS: Of the 4,880 adult patients, 915 (18.8%) were culture-negative. Culture-negative patients were less likely to report symptoms of TB disease and disease of longer duration. A multivariate analysis showed no statistically significant difference in loss to follow-up, treatment failure or recurrence between the culture-negative and -positive groups but a higher rate of death among culture-negative patients with an adjusted OR of 1.65 (95% CI 1.05-2.60). In a multivariate analysis of determinants of culture negativity, older age, substance use and being a secondary case were associated with culture status.CONCLUSIONS: More recognition and awareness of culture-negative TB is key for early and correct diagnosis to reduce transmission and improve treatment outcomes.

Prevalence of pyrazinamide resistance and Wayne assay performance analysis in a tuberculosis cohort in Lima, Peru.

BACKGROUND: Multidrug-resistant tuberculosis (MDR-TB) regimens often contain pyrazinamide (PZA) even if susceptibility to the drug has not been confirmed. This gap is due to the limited availability and reliability of PZA susceptibility testing. OBJECTIVES: To estimate the prevalence of PZA resistance using the Wayne assay among TB patients in Lima, Peru, to describe characteristics associated with PZA resistance and to compare the performance of Wayne with that of BACTEC™ MGIT™ 960. METHODS: PZA susceptibility using the Wayne assay was tested in patients diagnosed with culture-positive pulmonary TB from September 2009 to August 2012. Factors associated with PZA resistance were evaluated. We compared the performance of the Wayne assay to that of MGIT 960 in a convenience sample. RESULTS: The prevalence of PZA resistance was 6.6% (95%CI 5.8-7.5) among 3277 patients, and 47.7% (95%CI 42.7-52.6) among a subset of 405 MDR-TB patients. In multivariable analysis, MDR-TB (OR 86.0, 95%CI 54.0-136.9) and Latin American-Mediterranean lineage (OR 3.40, 95%CI 2.33-4.96) were associated with PZA resistance. The Wayne assay was in agreement with MGIT 960 in 83.9% of samples (κ 0.66, 95%CI 0.56-0.76). CONCLUSION: PZA resistance was detected using the Wayne assay in nearly half of MDR-TB patients in Lima. This test can inform the selection and composition of regimens, especially those dependent on additional resistance.

Cigarette smoking among tuberculosis patients increases risk of transmission to child contacts.

SETTING: Observational cohort study in Lima, Peru. OBJECTIVE: To determine the association between exposure to a smoking tuberculosis (TB) case and latent tuberculous infection (LTBI). METHOD: Between September 2009 and August 2012, we identified 2132 patients with drug-susceptible TB and their 2054 child household contacts. Data were collected on active and secondhand smoking status and other risk factors for infection specific to the index case, the household and the exposed contacts. Contacts underwent a tuberculin skin test (TST) to determine their tuberculous infection status at baseline, 6-month and 12-month follow-up. We estimated the association between exposure to a smoking index case and LTBI using a modified Poisson regression model. RESULTS: The 21 children (age â©¿15 years) exposed to smoking index TB patients were more likely to be TST-positive at baseline (RR 2.64, 95%CI 1.78-3.91), by 6 months (RR 1.91, 95%CI 1.40-2.60) and by 12 months (RR 1.48, 95%CI 1.07-2.06), than those who were not exposed. TST positivity among children at these time points did not vary with secondhand smoke exposure. CONCLUSIONS: TB patients who smoke may be more likely to transmit infection to their contacts. Interventions designed to reduce smoking among TB patients may minimise further spread of the disease.

The MIT D-lab electricity-free PortaTherm™ incubator for remote testing with the QuantiFERON®-TB Gold In-Tube assay.

BACKGROUND: Use of the QuantiFERON®-TB Gold In-Tube assay (QFT-GIT) in remote areas is limited by the need to incubate blood samples within 12 h of collection. PortaTherm™ is a portable, electricity-free, phase-change incubator previously used for field collection of microbiological samples. OBJECTIVE: To determine whether the PortaTherm can be used for the reliable incubation of QFT-GIT samples, thus enabling QFT-GIT use in settings distant from laboratory facilities. METHODS: In a prospective comparative study in Peru, blood samples were collected from 50 participants and processed in three parallel QFT-GIT tests per participant; two were incubated in a conventional incubator; the third was incubated in the PortaTherm. RESULTS: All 150 QFT-GIT tests gave definitive results, and for 46 of the 50 participants all three tests were concordant, eight of which were positive. Four participants had one discordant result: two due to discordance of a conventional incubator QFT-GIT result, and two due to discordant PortaTherm QFT-GIT results. CONCLUSION: The QFT-GIT inter-incubator variability between the PortaTherm and conventional incubator was no greater than the intra-incubator variability for the conventional incubator, indicating that the PortaTherm is a suitable tool for incubating QFT-GIT whole blood samples in remote settings where access to a laboratory or electricity is limited.