Predominance of gram-negative multidrug-resistant pathogens causing lower respiratory tract infections among gene X-pert negative presumptive tuberculosis patients in Dar Es Salaam, Tanzania

Background Lower respiratory tract infections (LTRIs) represent a significant global health burden. The clinical presentation of pulmonary tuberculosis (PTB) and other LRTIs often overlap, making it difficult to differentiate based on clinical features only. This study aims to investigate the role of other bacteria pathogens in LRTIs among presumptive TB patients and antibiotic susceptibility patterns for appropriate patient management. Materials and methods We conducted a cross-sectional study among patients with symptoms and signs suggestive of PTB at Muhimbili National Hospital and Infectious Diseases Centre in Dar es Salaam, Tanzania. Sputum samples collected for TB diagnosis using the original GeneXpert system were investigated for other causes of LRTIs. The sputum samples were assessed for quality based on the Bartlett criteria before culture. We performed descriptive statistics to summarize the data. Results We assessed 470 sputum samples, of which 317(67.4%) were of good quality. Of 317 samples, 21(6.6%) were Mycobacterium tuberculosis (MTB) positive by GeneXpert, while 126(39.7%) had 138 significant bacterial isolates other than MTB. Pseudomonas aeruginosa 44/99(44.4%) was the prominent Gram-negative bacteria isolated, followed by Klebsiella pneumoniae 22/99(22.2%). High rates of resistance was detected towards ampicillin (98%), penicillin (92%), and amoxicillin-clavulanic acid (65%). A high proportion of isolates, 71/138(51.4%) were multidrug resistant (MDR). Conclusion This study revealed a high prevalence of LRTIs caused by non-TB pathogens, particularly MDR strains in presumptive TB. MTB was detected only in high‑quality sputum samples. The high resistance rate to commonly prescribed antibiotics for LRTIs called for further large-scale studies to guide and/or refine treatment guidelines and optimize patient care.