Gram negative organisms in community acquired respiratory tract infections

Abstract

Objective: Respiratory tract infections (RTIs) are amongst the most common conditions encountered in our hospitals. The objectives of the study were to determine the frequency and antibiotic susceptibility pattern of various Gram negative bacteria (GNB) isolated from sputum samples of patients with RTIs. Methods: A descriptive, cross sectional study was carried out at the department of Microbiology, Army Medical College. Patients were diagnosed as suffering from RTIs on the basis of clinical features, radiological and laboratory findings. Sputum samples from all admitted and outdoor patients that presented to the hospital with RTIs were collected using sterile plastic containers. Those that satisfied the criteria for inclusion were accepted and processed according to routine microbiological procedures. The cultures were identified and susceptibility patterns of the organisms noted. Results: Fifteen hundred and ninety six sputum samples were processed of which 549 (34.4%) yielded a positive pathogenic organism on culture with 327 (59.6%) yielding GNB. Of these Pseudomonas aeruginosa 105 (32.1%) was the most frequently isolated organism followed by Heamophilus influenzae 62 (19.0%), Klebsiella pneumoniae 54 (16.5%), Acinetobacter 46 (14.1%) and E. coli 41 (12.5%). Piperacillin/tazobactam, meropenem and imipenem were among the most effective antibiotics. Conclusion: Gram negative bacteria are becoming an increasing cause of RTIs and hence demand an increased prudence and clinical insight in the treating clinician to keep on a lookout for these organisms as the causative agent of RTIs.