Antimicrobial resistance pattern of anaerobic bacteria causing lower respiratory tract infections.

Abstract

Abstract Background Anaerobes are indigenous flora of the human body but have the potential to cause serious diseases. Anaerobic bacteria are involved in all morbid conditions of respiratory infections, and the frequencies of isolation are high in pneumonia and at the time of acute exacerbation of chronic lower airway infection. These are often missed due to the complexity of their isolation and identification. Hence, this study aimed to study anaerobes causing respiratory tract infections and determine their antibiotic susceptibility. Materials & Methods Clinical specimens such as bronchial aspirates and pleural aspirates collected from patients with respiratory diseases attending Vallabhbhai Patel Chest Institute were processed, the anaerobes isolated were identified, and their susceptibilities to various groups of antimicrobials were studied using standard microbiological methods. Results Three hundred forty-four patients were included in the study, 124 males and 147 females. Of these 344 patients, 165 yielded anaerobes in their clinical samples. Ninety patients had more than one type of anaerobic organism. Hence, a total of 271 isolates were recovered belonging to as many as 16 genera. The MIC of seven antibiotics on 154 isolates was tested. The isolates belonged to the genera Bacteroides, Prevotella, Veillonella, and Actinomyces, among others. Variable resistance was observed to most classes of antibiotics by many genera. Conclusions Metronidazole is commonly used against anaerobes, but the study showed that the isolates were 20–30% resistant to the antibiotic. Starting this as an empirical therapy might lead to treatment failure.