Mycobacterium Tuberculosis (M.tb) and Bacterial Co-Infection in BAL Samples in a multi-centre UK cohort

Abstract

Background M.tb and bacterial co-infection can complicate the clinical presentation of tuberculosis (TB) and may require additional antibiotic therapy. Yet there are limited data describing M.tb with bacterial co-infection in BAL samples in immunocompetent individuals within a low TB incidence setting. Objective To study the prevalence of bacterial co-infections and comorbidities in a UK adult population with confirmed TB (positive culture or positive TB PCR) in BAL samples. Methods Patients who underwent a BAL (for suspected TB) were studied. Retrospective data were collected between 2018-2019 in one centre and prospective data collected in 2021-2022 across 10 UK centres. Electronic records were reviewed for demographic and clinical details. Results 58/569 had pulmonary TB treated (48 culture positive, 9 PCR positive-culture negative and 1 PCR trace-culture negative). 8 (14%) individuals had bacterial co-infection (table 1). In the co-infected group, mean age was 44 years (IQR 31.5- 52.5) and half were smokers, none were immunosuppressed (i. e DM, HIV, renal, immunosuppressive medications) nor had previous TB exposure. 6/8 co-infected individuals were migrants . Drug resistant TB was found in 1/8 of the coinfected cases. Cavities were noted in 9/58 (15.5%) confirmed TB cases of which 6/9 had bacterial co-infections (6/8 with bacterial co-infections had a cavity). In the co-infected group, time to positive AFB culture was 23 vs 20 days in the non-co-infected group. Conclusion There was a 14% rate of TB bacterial co-infection in our cohort. 66% of confirmed TB cases with cavities had a co-infection. Those with cavitary pulmonary lesions may have a higher risk of bacterial co-infection and this may need to be taken into account at presentation.