# First case report of Shewanella indica isolated from a hospitalized patient in Serbia

## TL;DR

This paper reports the first case of Shewanella indica in a critically ill patient in Serbia, highlighting the challenges in diagnosing rare bacterial infections.

## Contribution

The first documented case of S. indica in Serbia and the use of WGS to confirm its identity and resistance profile.

## Key findings

- S. indica was isolated from a critically ill patient with multiple comorbidities in Serbia.
- Whole-genome sequencing confirmed the isolate as S. indica and revealed multidrug resistance and virulence genes.
- Diagnostic tools like VITEK 2 and MALDI-TOF MS failed to accurately identify the species.

## Abstract

Over the past decade, Shewanella spp. have been increasingly recognized as opportunistic pathogens, particularly in patients with malignancies, neutropenia, severe heart failure, renal insufficiency, and hepatobiliary diseases. Shewanella indica is a rarely reported species within the Shewanella genus, and its role in human infection remains poorly documented. In this study, we report the first case of S. indica isolated from the stool of a critically ill 72-year-old man in Serbia with multiple pre-existing comorbidities and co-infections. Initial identification using the VITEK 2 system misclassified the strain as Shewanella algae, while species-level identification by the matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS) was inconclusive. However, whole-genome sequencing (WGS) definitively identified the isolate as S. indica and revealed a multidrug-resistant profile together with numerous virulence-associated genes. Minimum inhibitory concentrations (MICs) were determined for 32 antibiotics, although interpretation was constrained by the lack of species-specific breakpoints. This case highlights the diagnostic challenges in differentiating Shewanella indica, discusses its possible clinical roles, and underscores the value of genomic tools for accurate identification. It also reinforces the importance of recognizing rare pathogens in complex clinical scenarios.