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Routine investigations for tuberculosis on bronchoalveolar fluid lavage in a low-incidence setting: is it worth it?

C Sepulcri(1) R Barbieri(2) L Crupi(1,3) M Bonaffini(2,5) E Delfino(3) E Tagliabue(4) A Di Biagio(1,3) E Barisione(4) A Marchese(2,5) M Bassetti(1,3)

1:Division of Infectious Diseases, Department of Health Sciences (DISSAL), University of Genova, 16132 Genova, Italy; 2:Microbiology Unit, IRCCS Ospedale Policlinico San Martino, 16132 Genova, Italy; 3:Division of Infectious Diseases, IRCCS Ospedale Policlinico San Martino, 16132 Genova, Italy; 4:Interventional Pulmonology Unit, IRCCS Ospedale Policlinico San Martino, Genova, Italy; 5:Department of Surgical Sciences and Integrated Diagnostics (DISC), University of Genoa, 16132 Genoa, Italy

Italy has a low-incidence of tuberculosis (TB) (4.6/100.000 population); most cases occur in foreign-born residents from high-incidence countries. The value of routine investigations for TB on bronchoalveolar lavage fluid (BALF) in this setting is unclear.

In the Interventional Bronchoscopy Unit of a tertiary hospital in northern Italy screening diagnostics for TB on all BALF samples was implemented from 2016 with PCR (Xpert Ultra from 09/2018), microscopy and culture. We retrospectively analyzed all bronchoscopies performed from 01/09/2018 to 31/12/2023, assessing the rate of TB diagnosis (Xpert Ultra result as the index test) and the number of cases in which TB was not suspected (absence of: previous investigations for TB, written suspect of TB, IGRA test/tuberculin skin test performed). 

In the study period, 1694 BALF samples were investigated for TB, n=47(2.8%) were Xpert Ultra positive. Of these, n=40(85%) were requested with TB suspect from either an infectious diseases specialist (n=34, 85%), or from a pneumologist/internal medicine specialist (n=6,15%). In seven cases, there was no clear TB suspect at the time of bronchoscopy (0.4% of all bronchoscopies performed without TB suspect). All patients but one were Italian-born, mean age was 75.5 years (SD 9.5). The underlying suspect was lung malignancy in three, atypical pneumonia in four. In all cases, typical radiological findings and symptoms were absent.

The positivity rate of routine TB investigations on BALF was low, but it led to seven unexpected TB diagnoses, which is non-negligible in a low-incidence setting. TB should be suspected in elderly patients presenting with atypical pneumonia/query of pulmonary malignancy.

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