# Microbial Diversity and Infection Burden in Central Nervous System (CNS) Shunt and Drain Devices: A Prospective Observational Study

## TL;DR

This study examines infections linked to CNS shunt and drain devices, finding that Klebsiella pneumoniae is the most common cause, with higher infection rates during hot and humid months.

## Contribution

The study provides new insights into microbial diversity and infection patterns in CNS devices using MALDI-TOF identification and highlights seasonal trends.

## Key findings

- Klebsiella pneumoniae was the most frequently isolated organism from CNS devices.
- Device-associated infections were more common during hot and humid months, with a peak in September.
- Gram-negative organisms were predominantly responsible for these infections.

## Abstract

Introduction: Device-associated central nervous system infections are a subgroup of healthcare-associated infections that occur when either a temporary or permanent surgically implanted device becomes a source of infection. These devices are used to treat raised intracranial pressure due to hydrocephalus. These surgically implanted devices may become a source of infection due to colonization of microbes or contamination from the hospital environment. To determine the diversity of organisms involved in infection using MALDI-TOF-based identification, to assess the antimicrobial profiles of isolated organisms, and to calculate the rate of infection of these devices in our institution, we conducted this study.

Methods: This prospective observational study was conducted over one year at the Departments of Microbiology and Neurosurgery in a tertiary care teaching institute in North India. All patients with cerebrospinal fluid (CSF) drainage devices, such as external ventricular drains (EVDs), ventriculoperitoneal shunts (VPS), Ommaya reservoirs, and lumbar drains, with clinical suspicion of infection in the form of meningitis, meningoencephalitis, or ventriculitis, were included.

CSF samples were cultured on 5% sheep blood agar, chocolate agar, and MacConkey agar. Organisms from positive cultures were identified using matrix-assisted laser desorption/ionization time of flight (MALDI-TOF). Antimicrobial susceptibility was determined by the Kirby-Bauer disk diffusion method on Mueller-Hinton agar plates after preparing a 0.5 McFarland inoculum. The results were interpreted as per the Clinical and Laboratory Standards Institute guidelines, M100. Device-associated infection (DAI) rates were calculated monthly.

Results: A total of 107 patients were included. The majority of enrolled patients were men (male-to-female ratio: 1.97:1). Adults comprised 64.5% followed by infants (22.43%) and children (13.08%).

Most patients presented with vomiting (41.12%), headache (40.19%), and altered sensorium. VPS was the most commonly used device (65.4%), followed by EVD (30.14%). Among the 231 CSF samples received, 31 from 17 patients showed microbial growth. Klebsiella pneumoniae was the most frequently isolated organism (51.6%), followed by Pseudomonas aeruginosa (19.35%) and Acinetobacter baumannii (9.68%). Device-wise distribution showed that K. pneumoniae was the predominant organism isolated from EVD (42.8%), VPS (55.55%), and Ommaya reservoirs (83.33%). Infections were more common during hot and humid months, with the highest DAI rate in September (14.28%). Of the 107 patients, 83 were discharged, 15 died, and nine were lost to follow-up. Among the 17 patients, whose CSF cultures had shown growth of micro-organisms, 14 were discharged, two died, and one left against medical advice.

Conclusion: Our study highlights that DAIs are more prevalent with EVDs and are predominantly caused by Gram-negative organisms, with K. pneumoniae being the most frequently isolated. The susceptibility patterns underscore the need for regular antimicrobial surveillance and judicious antibiotic use to prevent the development of drug resistance. The seasonal variation in infection rates highlights the importance of stricter infection control measures during the high-risk months in hot and humid environments. Thus, early diagnosis, rational antibiotic use, and stringent infection control practices are essential for improving patient outcomes in neurosurgical settings.