Species identification and drug susceptibility testing of non-tuberculous mycobacteria by Line Probe Assay in Lambaréné, Gabon-a cross-sectional study.

BACKGROUND: Non-tuberculous mycobacteria (NTM) are a group of bacteria that cause rare lung infections and are increasingly recognized as causative agents of opportunistic and device-associated infections in humans. In Gabon, there is a lack of data on NTM species identification and drug susceptibility. The aim of this study was to identify the frequency of NTM species and their genotypic susceptibility pattern to commonly used antibiotics for NTM infections in Gabon. METHODS: A cross-sectional study was conducted at the CERMEL TB laboratory from January 2020 to December 2022, NTM subspecies identification and drug susceptibility testing to macrolides and aminoglycosides were performed using the genotype NTM-DR kit. RESULTS: The study found that out of 524 culture-positive specimens, 146 (28%) were NTM, with the predominant group being Mycobacterium avium complex (MAC) and Mycobacterium abscessus complex (MABC). All MAC isolates were fully susceptible to macrolides and aminoglycosides, while five MABC isolates carried mutations indicative of reduced susceptibility to macrolide and aminoglycoside drugs. CONCLUSIONS: These findings suggest that clinicians may use macrolides and aminoglycosides to manage NTM infections caused by MAC, but further investigation is required to determine MABC drug susceptibility.

Resistance patterns among drug-resistant tuberculosis patients and trends-over-time analysis of national surveillance data in Gabon, Central Africa.

OBJECTIVE: Routinely generated surveillance data are important for monitoring the effectiveness of MDR-TB control strategies. Incidence of rifampicin-resistant tuberculosis (RR-TB) is a key indicator for monitoring MDR-TB. METHODS: In a longitudinal nationwide retrospective study, 8 years (2014-2021) of sputum samples from presumptively drug-resistant tuberculosis patients from all regions of Gabon were referred to the national tuberculosis reference laboratory. Samples were analysed using GeneXpert MTB/RIF and Genotype MTBDRsl version 2/Line Probe Assay. RESULTS: Of 3057 sputum samples from presumptive tuberculosis patients, both from local hospital and from referral patients, 334 were RR-TB. The median patient age was 33 years (interquartile range 26-43); one third was newly diagnosed drug-resistant tuberculosis patients; one-third was HIV-positive. The proportion of men with RR-TB was significantly higher than that of women (55% vs 45%; p < 0.0001). Patients aged 25-35 years were most affected (32%; 108/334). The cumulative incidence of RR-TB was 17 (95% CI 15-19)/100,000 population over 8 years. The highest incidences were observed in 2020 and 2021. A total of 281 samples were analysed for second-line drug resistance. The proportions of study participants with MDR-TB, pre-XDR-TB and XDR-TB were 90.7% (255/281), 9% (25/281) and 0.3% (1/281), respectively. The most-common mutations in fluoroquinolones resistance isolates was gyrA double mutation gyrA MUT3B and MUT3C (23%; 4/17). Most (64%; 6/8) second-line injectable drugs resistance isolates were characterised by missing both rrs WT2 and MUT2 banding. CONCLUSION: The increasing incidence of MDR-TB infection in Gabon is alarming. It is highest in the 25-35 years age category. The incidence of MDR-TB infection in treatment-naïve patients calls for case finding and contact tracing strategy improvement.