Bacterial Etiology and Antimicrobial Resistance in Community-Acquired Pneumonia Among Adults in Kano State: A Prospective Study

Community-acquired pneumonia (CAP) is a leading cause of adult hospitalization and mortality in Nigeria, yet the bacteriological etiology and resistance landscape in the North West zone remain poorly characterized, limiting evidence-based empirical therapy guidelines. This prospective analytical study determined the bacterial etiology and antimicrobial resistance profiles of CAP in adult patients admitted to Aminu Kano Teaching Hospital, Kano State, in the North West geopolitical zone of Nigeria. A total of 180 adult patients with WHO-defined CAP were enrolled over 12 months. Sputum, blood cultures, and urinary antigen tests for Streptococcus pneumoniae and Legionella pneumophila were performed. Bacterial isolates were identified and subjected to antimicrobial susceptibility testing per CLSI 2023 guidelines. A microbiological etiology was established in 64.4 percent of cases. Streptococcus pneumoniae was the most frequently isolated pathogen at 28.4 percent, followed by Klebsiella pneumoniae at 22.6 percent and Staphylococcus aureus at 17.2 percent. Penicillin non-susceptibility was detected in 42 percent of pneumococcal isolates. MDR Klebsiella accounted for 58.3 percent of K. pneumoniae isolates. Mortality was highest in patients infected with MDR Klebsiella or MRSA. These findings provide the first comprehensive CAP etiology and resistance data from Kano State and support revision of empirical CAP treatment guidelines to include coverage for MDR Gram-negative organisms in hospitalized patients. Keywords: community-acquired pneumonia, Streptococcus pneumoniae, antibiotic resistance, Kano, bacterial etiology.