Characterization and Antimicrobial Susceptibility Pattern of Non-fermenting Gram-negative Bacilli and Molecular Analysis of Pseudomonas Species from Respiratory Samples of Intensive Care Unit Patients in A Tertiary Care Hospital

Abstract

Among patients admitted to the intensive care unit (ICU) the most common cause of infection is lower respiratory tract infections, which account for 4.4% of hospital admissions. Among the non-fermenters, Pseudomonas aeruginosa and Acinetobacter calcoaceticus-baumannii complex, cause many types of nosocomial infections. Ventilator-associated pneumonia is the most common emerging infection among them. The goal of this study was to isolate and speciate non-fermenting Gram-negative organisms from respiratory samples of ICU patients and to detect antimicrobial susceptibility patterns of the isolated non-fermenters. This cross-sectional study was conducted at the Institute of Microbiology in collaboration with Medical Intensive Care units in Rajiv Gandhi Government General Hospital. A total of 200 patients who satisfied the inclusion criteria were included in the study conducted between March 2019 and March 2020. Culture, sensitivity, and anti-microbial susceptibility tests were performed for the respiratory samples collected as per standard protocols. Pseudomonas aeruginosa (49%) was the most commonly isolated non-fermenter followed by Acinetobacter baumannii (24.3%). Among Pseudomonas aeruginosa isolates, the highest percentage were ESBL producers (44.4%). Carbapenem resistance among Pseudomonas isolates was 33%. The study showed increased isolation of MDR non-fermenters from the ICU causing Ventilator-associated pneumonia (VAP). To prevent VAP caused by these MDR pathogens, clinicians should follow strict infection control practices, use invasive devices on a short-term basis, and use antibiotics judiciously.