Microbiological Spectrum, Susceptibility, Testing, and Antibiotic Resistance Mechanism with Special Reference to ESBL, MBL and MRSA in Clinical Isolates from Patients with Lower Respiratory Tract Infection (LRTI) at a Tertiary Care Centre

Introduction: Lower respiratory tract infections (LRTIs), like as community-acquired pneumonia (CAP), hospital-acquired pneumonia (HAP), and ventilator-associated pneumonia (VAP), are the fourth leading cause of death and the most frequent cause of illness worldwide, contributing to substantial morbidity and mortality. This study aimed to identify the potential etiological agent with LRTIs in OPD and IPD patients, their resistance pattern and mechanism associated with it. Methodology: Specimens collected from both OPD and IPD patients including ICU from RUHS Hospital of Medical Sciences, Jaipur and State Cancer Institute, Pratap Nagar, Jaipur, were included in the study. Specimens were sent to the Microbiology department, for processing by Gram staining, bacteriological culture, culture sensitivity and detection of antibiotic resistance mechanism as per standard protocol In Gram egative acteria (GNB) Antibiotic Resistance, Klebsiella pneumoniae, Pseudomonas aeruginosa, Mixed Infection. Results: A total of 1094 samples were obtained from the OPD, IPD and ICU. Culture positivity was 36.29% (397/1094) for either single pathogen or mixed infection, out of which 71% were male and 29% were female. Klebsiella pneumoniae 21.41% (85/397), and in Gram positive cocci (GPC) Enterococcus spp. 7.53% (28/397) was the most prevalent pathogen isolated. Coagulase negative Staphylococci (CONS) showed 50% methicillin resistance as compared to 47% in COPS. Extended spectrum beta-lactomase (ESBL) production was found in Escherichia coli which showed prevalence of 73% as compared to the GNB. Acinetobacter spp. was the most resistant organism show-ing ESBL production in 100%, and metallo-beta lactamase (MBL) production in 70% of isolates. Conclusion: LRTIs are common among community due to irrational use of antibiotics results in therapeutic failure.