PHENOTYPIC AND GENOTYPIC CHARACTERISTICS OF BACTERIAL ISOLATES FROM SPUTUM AND THEIR SUSCEPTIBILITY PATTERNS TO SOME SELECTED ANTIBIOTICS

ABSTRACT Lower respiratory tract infections (LRTIs) remain a leading cause of morbidity and mortality worldwide, particularly in developing regions. Sputum cultures are pivotal in identifying bacterial pathogens responsible for these infections. The aim of the study is to investigate the phenotypic and genotypic characteristics of bacteria isolated from sputum samples and evaluate their susceptibility to selected antibiotics. A total of 50 sputum samples were collected, of which 40 samples yielded bacterial growth, which is 80% of the total samples. The samples were cultured on blood agar and nutrient agar, and isolates were identified based on morphological characteristics and biochemical tests. Gram-negative bacteria were about 55% that is Klebsiella pneumoniae is 50% and Pseudomonas aeruginosa is 5% while Gram-positive bacteria, Staphylococcus aureus was 45%. Antibiotic sensitivity testing (AST) was done using the modified Kirby-Bauer disc diffusion method on Muller-Hinton Agar. The most effective antibiotics are gentamicin which is an aminoglycoside and levofloxacin which is a fluoroquinolone antibiotic while the less effective antibiotics are ampicillin and Augmentin. Polymerase Chain Reaction (PCR) which is a molecular technique was used in identifying the genomic sequence (16s rRNA gene) of the most dominant isolate, and the particular strain (S. aureus strain CFSAN082783) was identified. The study demonstrated the phenotypic and genotypic characteristics of isolated bacteria, and highlighted prevalent and predominant nature of K. pneumoniae followed by S. aureus.