Abstract
<title>Abstract</title> <p> VAP is a common health-related illness among critically ill individuals receiving extended ventilation in intensive care units (ICUs). The rise of multidrug-resistant (MDR) Gram-negative bacilli (GNB) has created a substantial problem in the treatment and management of VAP. The current study focused on the prevalence, biochemical characteristics, antibiotic susceptibility testing (AST) patterns, and epidemiological distribution of MDR-GNB associated with VAP in ventilated ICU patients. MALDI-TOF MS study showed the presence of 99.9% of <italic>E.coli</italic> , <italic>A. baumanii</italic> and <italic>P. aeroginosa</italic> and this result also substantiate for choosing VAP associated pathogen to further analysis of biochemical characterization and AST profiling. A total of 120 patients samples were examined using standard microbiological techniques, biochemical characterization, AST and 16S rRNA sequencing. Gram staining revealed GNB, which were then separated into lactose-fermenting (LF) and non-lactose-fermenting (NLF) isolates using standard biochemical methods. The most common LF isolates were <italic>E. coli</italic> and <italic>K. pneumoniae</italic> , while <italic>A. baumannii</italic> and <italic>P. aeruginosa</italic> were the most common NLF pathogens found. The AST and VITEK results demonstrated increased resistance to Ceftriaxone (CTR), Cotrimoxazole (COT), and Gentamicin (GEN), whereas Imipenem (IPM) and Meropenem (MEM) remained relatively effective against multiple isolates. <italic>A. baumannii</italic> exhibited the highest level of multidrug resistance of any organism, but <italic>P. aeruginosa</italic> showed varying susceptibility patterns. Prolonged ICU stays, prior antibiotic exposure, and extended ventilator use were found to be key risk indicators for MDR infections in an epidemiological study. The study underlines the increased burden of MDR Gram-negative organisms in VAP and the necessity of continuous surveillance, rapid molecular diagnosis, infection management techniques and antibiotic stewardship programs in ICUs. </p>