Identification and specie-typing of nontuberculous mycobacteria among sputum samples of presumed and diagnosed drug-resistant tuberculosis patients in Ghana, a 10-year retrospective laboratory analysis
E T Abbew(1,2,3) R Laryea(4) F Sorvor(5) Y Aduse-Poku(5) N Lorent(6) T Decroo(1) D Obiri-Yeboah(7) L Lynen(1) L Rigouts(1,2)
1:Institute of Tropical Medicine, Antwerp; 2:University of Antwerp; 3:Cape Coast Teaching Hospital, Ghana; 4:Eastern Regional Hospital, Ghana; 5:National Tuberculosis Control Program Ghana; 6:University Hospitals, Leuven; 7:University of Cape Coast, Ghana
The awareness of nontuberculous mycobacterial pulmonary disease (NTM-PD) is rising worldwide with the increasing isolation of NTM from sputum samples. In 2009, Ghana started using mycobacteria growth indicator tube (MGIT) for diagnosing and monitoring drug-resistant tuberculosis (DR-TB) patients, also resulting in increasing isolation of NTM species.
We retrospectively analysed existing laboratory data from 2012-2021 from the Eastern Regional Hospital (ERH) and Cape Coast Teaching Hospital (CCTH). All sputum samples had microscopy and culture done using MGIT and solid medium. All probable NTM isolates were stored at -20oC. After regrowing them in MGIT they were characterised using GenoType CM/AS (Bruker, Germany).
A total of 2492 sputum samples were analysed with smear and culture over the ten years, with one-third of them being culture positive (33.7%). Of these, 30.6% were classified and stored as NTM.
Overall, of 225 NTM isolates that could be regrown, 15.1% were M. intracellulare, 4.9% were M. fortiutum, 0.9% were M. abscessus, 0.9% were M. malmoense, 0.4% were M. avium and M. gordonae. A further 8% were identified as MTB complex. 37.5% isolates could not be identified; they will undergo Sanger sequencing using the 16rRNA and/or rpoB targets. An important proportion (19.1%) remained negative by the Genotype assays.
The isolation and identification of potentially pathogenic NTM species in this TB-endemic setting suggests that incorporating NTM species identification in the routine work flow may help with clinical decision-making of NTM-PD in Ghana.