# Case Report: From lung to peritoneum: genomic and immunologic insights into a rare dual-site Corynebacterium striatum infection

## TL;DR

A rare case of multi-site Corynebacterium striatum infection in an immunocompromised patient is analyzed using genomic and immunologic methods.

## Contribution

The case provides genomic evidence of clonal spread of C. striatum across multiple sites in a postoperative immunocompromised patient.

## Key findings

- Highly homologous C. striatum strains were isolated from lung and peritoneum with only 54 SNPs difference.
- ermX-mediated resistance and susceptibility to vancomycin and linezolid were identified via whole-genome sequencing.
- Targeted therapy and drainage led to full recovery, emphasizing the need for early molecular typing and tailored treatment.

## Abstract

Corynebacterium striatum is an emerging multidrug-resistant pathogen in immunocompromised patients. We report a 75-year-old male with paranoid schizophrenia on long-term clozapine who developed sepsis after gastric perforation repair. Within two days, genetically highly homologous Corynebacterium striatum strains were isolated from bronchoalveolar lavage fluid and ascitic fluid. Whole-genome sequencing revealed only 54 Single Nucleotide Polymorphisms (SNPs) differences, identical ermX-mediated resistance, and susceptibility to vancomycin and linezolid. Targeted therapy combined with drainage led to full recovery. This case highlights the potential for multi-site clonal infection via ICU environmental spread or endogenous translocation in the setting of postoperative immune suppression and invasive devices. Early multi-site sampling, molecular typing, and tailored antimicrobial therapy are essential, particularly in psychiatric patients requiring coordinated infection and psychiatric care.