Abstract
Background
Lower respiratory tract infections are among the major causes of morbidity and mortality in the world. This study aims to analyze the bacteriological profile of lower respiratory tract infections in the patients visiting Shukraraj Tropical and Infectious Disease Hospital in Kathmandu during three-month period from April to June 2023 and the antibiotic susceptibility pattern of the isolated pathogens.
Method
312 sputum samples were examined through Gram staining, microscopy, culture and various biochemical tests and significant bacterial isolates were identified. Antibiotic susceptibility testing was done by modified Kirby-Bauer disc diffusion method using different sets of antibiotics for different bacteria and Multi-drug Resistant (MDR) isolates were identified. The Methicillin Resistant S. aureus (MRSA) isolates were determined via antibiotic susceptibility testing against 30µg-Cefoxitin disc in Mueller Hinton Agar.
Results
34 out of the total 312 sputum samples examined showed significant growth. Gram-negative bacilli (85.29%) had a significant proportion compared to Gram-positive (14.71%). The most prevalent bacteria causing LRTI was found to be Klebsiella pneumoniae (32.35%) followed by Pseudomonas aeruginosa(29.41%), Acinetobacter spp.(17.65%), Staphylococcus aureus(14.71%), Enterobacter spp.(2.94%), and Citrobacter spp.(2.94%). Gentamicin exhibited the highest sensitivity rate of 75.86% in case of Gram-negative isolates and it showed highest resistance to Amoxicillin (86.21%). For Staphylococcus aureus, Linezolid, Vancomycin and Teicoplanin showed highest susceptibility rate of 100% followed by Gentamicin (60%). 20.70% of Gram-negative isolates were Multi-drug Resistant among which the predominant one was found to be Acinetobacter spp. (83.33%) followed by Klebsiella pneumoniae(16.67%). For S. aureus, all the isolates (100%) were found to be multi-drug resistant. 80% of S. aureus isolates were found to be Methicillin Resistant Staphylococcus aureus.
Conclusion
Gram-negative bacteria were found to be leading causative agents (85.29%) of lower respiratory tract infections. Antibiotics like Ciprofloxacin and Gentamicin were found to be effective against majority of Gram-negative bacteria. Similarly, Linezolid, Vancomycin and Teicoplanin were useful against Methicillin resistant S. aureus. The study recommends a periodic analysis on bacteriological agents of such infections and their antibiotic susceptibility pattern in order to assess the increasing anti-microbial resistance in pathogens and adjust the empirical therapy accordingly.