Advanced Insights Into Intravascular Bloodstream Infections: A Cross-Sectional Study of the Molecular Characterization of World Health Organization Priority Pathogens and Antimicrobial Resistance Patterns at a Tertiary Care Hospital

Introduction Bloodstream infections (BSIs), particularly intravascular types such as catheter-related bloodstream infections (CRBSIs) and infective endocarditis (IE), represent a significant public health challenge due to their high morbidity and potential to rapidly progress to sepsis. The emergence of multidrug-resistant (MDR) pathogens necessitates molecular surveillance to inform effective antimicrobial strategies, especially in regions like India, where resistance data is limited. Methods A cross-sectional study was conducted over seven months, enrolling 101 patients from cardiology, nephrology, and ICUs at a tertiary care hospital in Chennai. Patients with confirmed intravascular BSIs were identified using clinical criteria and modified Duke's definitions. Blood cultures and catheter tip analyses were performed using standard microbiological techniques. Phenotypic resistance mechanisms were assessed via extended-spectrum beta-lactamase (ESBL), methicillin resistance, and CARBA NP testing. Molecular characterization included polymerase chain reaction (PCR) detection of resistance genes (blaKPC, blaNDM, blaCTX-M, blaTEM, OXA-23, OXA-48, mecA). Data were analyzed using IBM SPSS Statistics Version 31.0 (IBM Corp., Armonk, NY). Means and proportions were reported with 95% confidence intervals (CIs). Results The cohort included patients aged 13-68 years, with a male predominance (70 patients, 70%). CRBSIs accounted for 86 cases (85%). All patients underwent internal jugular vein (IJV) catheterization, primarily for hemodialysis in chronic kidney disease (CKD) (68 patients, 68%). Blood culture positivity was observed in 49 patients (48.5%), with Klebsiella pneumoniae (14 patients, 13.9%), Pseudomonas spp. (10 patients, 9.9%), and Staphylococcus aureus (8 patients, 7.9%) as dominant isolates. ESBL production was highest in Escherichia coli (four out of five isolates, 80%) and Klebsiella (10 out of 14 isolates, 71.4%). Carbapenemase genes blaNDM and blaKPC were detected in five out of 14 Klebsiella isolates (35.7%), while OXA-23 was found in five out of six Acinetobacter isolates (83.3%). A significant correlation was found between catheter duration and culture positivity using a scatter plot demonstration. Targeted antimicrobial therapy was successful in 71 patients (70%), although complications such as persistent bacteremia and septic shock were noted. Conclusions This study underscores the high prevalence of CRBSIs and the concerning presence of molecular resistance markers in key pathogens. The predominance of carbapenemase genes such as blaNDM, blaKPC, and OXA variants highlights the urgent need for molecular diagnostics and robust antibiotic stewardship in India. Continued surveillance of intravascular BSIs and resistance profiles is essential to improve clinical outcomes and combat antimicrobial resistance.