# Frequency and antimicrobial resistance pattern of non lactose fermenting gram negative rods in neurosurgical patients outlining aminoglycoside resistance genes

## TL;DR

This study examines antibiotic resistance in non-lactose fermenting gram-negative rods causing hospital infections in neurosurgical patients, focusing on resistance to aminoglycosides.

## Contribution

The study identifies the prevalence and resistance patterns of NFGNRs in neurosurgical patients, with a focus on aminoglycoside resistance genes.

## Key findings

- Pseudomonas aeruginosa and Acinetobacter baumannii were the most common NFGNRs causing HAIs.
- 63.5% of NFGNRs were resistant to aminoglycosides, with armA being the most detected resistance gene.
- High resistance rates to gentamicin, amikacin, and meropenem were observed in both P. aeruginosa and A. baumannii.

## Abstract

Non-Fermenting Gram-Negative Rods (NFGNRs) are one of the major causes of hospital-acquired infections (HAIs) with high levels of antibiotic resistance. The patients following neurosurgery are continuously at risk of HAIs due to the severity of the brain insult. We aimed to assess the frequency and the characterization of antimicrobial resistance patterns among NFGNR-causing HAIs isolated from neurosurgical patients with special reference to the aminoglycoside resistance.

A cross-sectional study was conducted on the hospitalized neurosurgical patients at Fayoum University Surgical Hospital, Egypt. The demographic characteristics and clinical data of patients were reported. The HAI definition was used by the Centers for Disease Control and Prevention (CDC). From 120 patients, one hundred and thirty-one samples were obtained and cultured on an appropriate media. NLFGNRs were identified using standard microbiological methods and VITEK2. Antimicrobial susceptibility testing was evaluated using the disc diffusion method. PCR was used to detect the aminoglycosides-resistant genes. Simple descriptive statistical analysis for results was done using statistical software, SPSS version 24. The chi-square and Fisher’s exact test for the bivariate relationship were performed.

One hundred and forty-six strains were isolated. NFGNRs represented [63/146 (43.1%)]. The most frequent NFGNRs were Pseudomonas aeruginosa
(P. aeruginosa) (66.7%) and Acinetobacter baumannii (A. baumannii) (33.3%). 63.5% of NFGNR were resistant to aminoglycosides. P. aeruginosa exhibited a higher rate of resistance to gentamicin (62%), amikacin (59.5%), and meropenem (57.1%). In addition, A. baumannii was resistant to gentamicin (76.1%), amikacin (62%), and meropenem, ceftazidime (57.1%) for both. armA gene was the most detected aminoglycoside resistance gene (97.7%), followed by aac(3ʹ)-IIa (59.1%).

We reported a high prevalence of NFGNRs (43.1%) causing HAIs among neurosurgical patients with increased antibiotic resistance for gentamicin. This makes a significant challenge for continued surveillance of antibiotic resistance and the improvement of the antimicrobial stewardship program to lower the frequency of NFGNR infections among neurosurgical patients.