# Epidemiological Study of Lactose- and Non-lactose-Fermenting Gram-Negative Bacterial Isolates From Clinical Specimens in the Middle Al-Furat Region of Iraq

## TL;DR

This study analyzed 682 clinical samples from Iraq's Middle Euphrates region to identify Gram-negative bacteria and assess their antibiotic resistance.

## Contribution

The study provides new insights into the prevalence and antibiotic resistance patterns of lactose- and non-lactose-fermenting Gram-negative bacteria in a specific Iraqi region.

## Key findings

- E. coli was the most common lactose-fermenting isolate (47.7%), followed by Klebsiella pneumoniae and Enterobacter cloacae.
- Pseudomonas aeruginosa and Acinetobacter baumannii were the most common non-lactose-fermenters.
- Ampicillin and amoxicillin/clavulanic acid showed the highest efficacy against the isolates.

## Abstract

Background: The study included a collection of 682 clinical samples from the hospital laboratories all over Iraq's Middle Euphrates region, which encompasses the governorates of Najaf, Karbala, Babylon, and Diwaniyah. The study lasted for seven months, from April 2022 to the end of October 2022, and aimed to isolate and diagnose Gram-negative lactose-fermentative bacterial species while determining the extent of multidrug resistance (MDR) of the isolated bacteria to antibiotics.

Method: Swabs were quickly taken to the lab in a special solution and placed on different types of growth media, like blood agar, nutrition agar, and MacConkey agar, and then the Vitek Compact 2 system was also used to confirm the identification of the bacteria. Susceptibility to antimicrobials was assessed according to the CLSI guideline.

Results: Six hundred and eighty-two Gram-negative bacterial isolates revealed that 468 (68.6%) were lactose-fermenting species, including E. coli (47.7%, 325/682), Klebsiella pneumoniae (13.9%, 95/682), and Enterobacter cloacae (7.0%, 48/682), while 214 (31.4%) were non-lactose-fermenters, predominantly Pseudomonas aeruginosa (10.6%, 72/682), Acinetobacter baumannii (8.5%, 58/682), Salmonella typhi (8.9%, 61/682), and Proteus mirabilis (3.4%, 23/682). Antibiotic susceptibility testing showed the highest efficacy for ampicillin (84.2%) and amoxicillin/clavulanic acid (75.5%), followed by cefotaxime (75.5%), ceftazidime (71%), imipenem (58.4%), and meropenem (63.8%), with all isolates exhibiting significant resistance (p < 0.0001)

Conclusion: This work emphasizes the place of the Gram-negative bacteria as nosocomial and community-acquired pathogens. The rates of resistance are in accordance with a public health problem in the Middle Euphrates region.