# A Retrospective Observational Study of the Microbial Etiology and Antimicrobial Susceptibility Patterns of Blood Cultures From ICU Patients at a Healthcare Facility in North India

## TL;DR

This study analyzed blood cultures from ICU patients in India to identify common microbes and their antibiotic resistance patterns.

## Contribution

It provides new data on microbial etiology and antimicrobial resistance in ICU patients in North India.

## Key findings

- Coagulase-negative Staphylococci were the most common isolate in blood cultures.
- Gram-negative bacteria showed high resistance to most drugs, while vancomycin and linezolid were effective against gram-positive bacteria.
- Blood cultures are essential for diagnosing septicemia and guiding appropriate antibiotic use.

## Abstract

Introduction

Bloodstream infections (BSI) are a leading source of fatalities and morbidity in hospitals. However, the clinical spectrum and antimicrobial resistance differ globally. Identifying the pathogenic spectrum and variations in antibiotic resistance is crucial for controlling BSI and preventing inappropriate antibiotic use.

Material and methods

This retrospective observational study was conducted at the Dr. Ram Manohar Lohia Institute of Medical Sciences, Lucknow, UP, India, for one year between June 2022 and June 2023. A total of 669 adult patients' blood cultures were obtained from ICUs. Blood culture was done using a BacT/Alert 3D (BioMérieux SA, Marcy-l'Étoile, France) automated system. Identification of the bacterial as well as fungal isolates was done using matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS), and the antimicrobial susceptibility profile was analyzed using the VITEK 2 Compact system (BioMérieux SA).

Results

Of the 669 blood culture samples, 213 (31.8%) showed bacterial or fungal growth. Of these 213 isolates, the most common isolate was coagulase-negative Staphylococci (21.6%), followed by Klebsiella pneumoniae (19.3%) and Acinetobacter spp. (17.8%). The majority of gram-negative bacteria were resistant to most drugs, and vancomycin and linezolid were both effective against the majority of gram-positive bacteria.

Conclusion

The current study found that septicemia was more frequently caused by gram-negative bacteria than by gram-positive bacteria. Blood cultures are always necessary in cases of suspected septicemia, and once the antimicrobial susceptibility profile of the pathogen causing septicemia has been determined, suitable antimicrobials should be prescribed and used to lower the antimicrobial resistance burden.