# Gram-Negative Bacterial Infections in Cardiac Implantable Electronic Devices: Insights from a Retrospective Analysis of Multidrug-Resistant and Non-Multidrug-Resistant Isolates

## TL;DR

This study examines cardiac device infections caused by Gram-negative bacteria, comparing outcomes between multidrug-resistant and non-resistant cases.

## Contribution

The study provides clinical insights into the differences between multidrug-resistant and non-resistant Gram-negative CIED infections.

## Key findings

- Pseudomonas aeruginosa was the most common isolated species in CIED infections.
- MDR infections showed trends toward higher disease severity and delayed device extraction.
- Blood culture positivity was higher in MDR cases compared to non-MDR cases.

## Abstract

Cardiac implantable electronic device (CIED) infections caused by Gram-negative bacteria are uncommon but potentially life-threatening. This study examined patients with Gram-negative CIED infections, investigating the clinical characteristics of patients harboring multidrug-resistant (MDR), versus non-MDR, isolates. A retrospective observational analysis was conducted at two tertiary Greek University Hospitals from 2015 to 2020. Patients were identified through microbiological cultures from device-related sites (pocket, lead, generator), with infections classified as MDR or non-MDR based on antimicrobial susceptibility profiles. Comprehensive data were collected, including demographic characteristics, clinical parameters, procedural details—on both the last device procedure and subsequent extraction procedure—infection-related findings, and microbiological profiles. In total, 18 patients were identified, with an equal distribution of 9 MDR and 9 non-MDR cases. The study population had a median age of 78 years, with 33.3% female patients, and a median Charlson Comorbidity Index of four. Pseudomonas aeruginosa was the most prevalent isolated species. Comparative analysis revealed that MDR patients had higher median SOFA (Sequential Organ Failure Assessment) scores (2 vs. 0, p = 0.07), longer time to device extraction (50% vs. 88.9% extracted within one month, p = 0.079), and higher blood culture positivity (80% vs. 37.5%, p = 0.135). Despite similar demographic characteristics, MDR infections demonstrated more complex clinical profiles, with a trend towards increased disease severity.