MICROBIOLOGICAL PROFILE AND ANTIBIOTIC RESISTANCE PATTERN OF RESPIRATORY PATHOGENS ISOLATED FROM SPUTUM SAMPLES: A PROSPECTIVE OBSERVATIONAL STUDY

Abstract

Introduction: Respiratory tract infections are common reasons for sputum culture and empirical antibiotic therapy. Increasing antimicrobial resistance among Gram-negative respiratory isolates has reduced the dependability of routinely used beta-lactam antibiotics. Local antibiogram data are therefore necessary for rational treatment selection and antimicrobial stewardship.

Aim: To determine the microbiological profile of organisms isolated from sputum samples and to assess the antibiotic resistance pattern of major bacterial respiratory pathogens.

Materials and Methods: This prospective observational study included 1500 non-duplicate sputum samples collected from clinically suspected respiratory tract infection cases. Among the study samples, 600 (40.0%) were from males and 900 (60.0%) were from females. Adults aged 18-64 years constituted the largest group 910 (60.7%), followed by elderly patients aged ≥65 years 510 (34.0%), adolescents aged 13-17 years 50 (3.3%) and children aged 1-12 years 30 (2.0%). All samples were cultured on Blood agar and MacConkey agar and incubated aerobically at 37°C for 18-24 hours. Isolates were identified using colony characteristics, Gram staining, standard biochemical reactions and VITEK-2 when required. Antibiotic susceptibility testing was performed by Kirby-Bauer disc diffusion method and interpreted according to Clinical and Laboratory Standards Institute recommendations. Data were analysed using descriptive statistics, and frequencies and percentages were calculated for culture outcome, demographic distribution, isolate profile and antibiotic resistance pattern.

Results: Pathogenic growth was obtained in 660 of 1500 samples (44.0%). Females contributed 900 samples (60.0%) and adults aged 18-64 years formed the largest group (910, 60.7%). Among pathogenic isolates, Klebsiella pneumoniae was most frequent (290, 43.9%), followed by Pseudomonas aeruginosa (130, 19.7%), Candida albicans (110, 16.7%) and Escherichia coli (90, 13.6%). Resistance was high to ceftriaxone, cefuroxime and amoxiclav, while comparatively lower resistance was observed with imipenem and meropenem.

Conclusions: Gram-negative bacteria predominated among sputum isolates, with substantial resistance to commonly used antibiotics. Routine culture, periodic antibiogram review and culture-guided de-escalation are important for effective respiratory infection management.