# Isolation and identification of Pseudoxanthomonas winnipegensis from blood culture by MALDI-MS

## TL;DR

This paper describes the first isolation of Pseudoxanthomonas winnipegensis from human blood in Japan and shows how MALDI-MS can help identify these rare bacteria quickly.

## Contribution

The study introduces MALDI-MS marker peaks for rapid identification of Pseudoxanthomonas species in clinical settings.

## Key findings

- P. winnipegensis was first isolated from a human blood sample in Japan in 2022.
- MALDI-MS using ribosomal proteins L29, L33, and CspA can reliably identify Pseudoxanthomonas species.
- Routine microbiological tests struggle to accurately identify Pseudoxanthomonas species.

## Abstract

Pseudoxanthomonas is a genus primarily isolated from environmental samples and causes opportunistic infections. In this study, we conducted a detailed investigation of P. winnipegensis, which was isolated for the first time from a blood sample in Japan in 2022, and evaluated five Pseudoxanthomonas species, including P. kaohsiungensis, P. japonensis, P. mexicana, P. spadix and P. winnipegensis, that cause human infections. However, it is difficult to identify accurately by routine microbiological testing. Our analysis revealed that matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) classification is feasible when using the mass peaks corresponding to ribosomal proteins L29 and L33, as well as the cold-shock protein CspA, as marker peaks. These findings indicate the potential of MALDI-MS for the rapid and reliable detection of Pseudoxanthomonas species in routine microbiological diagnostics.