Screening for TB by sputum culture in high-risk groups in Copenhagen, Denmark: A novel and promising approach

Abstract

Introduction: Evidence on screening high-risk groups for TB by mobile X-ray in low-incidence countries is building, but knowledge on other possible screening methods is limited. In this retrospective study we report results from a community based programme screening for TB by spot sputum culture. Methods: On seven occasions, from September 2012 through June 2014, we offered TB screening to all persons present at 11 locations where socially marginalised people gather in Copenhagen. Spot sputum samples from participants were examined by smear microscopy and culture. Genotype, nucleic acid amplification test and chest X-ray were done if TB was found. Results: Among 1075 participants, we identified 36 cases of TB. Twenty-four cases (66.7%) were identified at the first screening of each participant, that is, the prevalence of TB was 2233/100 000. Thirty-five (97%) of the TB cases were culture-positive and seven (19.4%) were smear-positive. Twelve out of 21 (57.1%) cases tested were nucleic acid amplification test positive. Twenty-eight (77.8%) had chest X-ray suggestive of TB. All patients with TB started treatment, 30 (83.3%) had a successful outcome. Discussion: Screening for TB by spot sputum culture is possible and a promising alternative to mobile X-ray in a community based screening programme. 22.2% did not have chest X-ray suggestive of TB and would not have been identified using mobile X-ray. Most of the TB cases were smear-negative, suggesting that they were identified at an early, less infectious stage, which is essential in order to prevent transmission and gain infection control.