Unusual case of Myroides odoratimimus infection in a cancer patient: addressing its antimicrobial resistance mechanisms and review of the literature

Front Cell Infect Microbiol. 2026 Apr 30:16:1647777. doi: 10.3389/fcimb.2026.1647777. eCollection 2026.

Abstract

Introduction: Myroides odoratimimus is a Gram-negative opportunistic pathogen primarily affecting immunocompromised individuals. However, its resistance characteristics and therapeutic response in cancer patients remain poorly defined. This study investigated the antimicrobial resistance profile of a urinary M. odoratimimus isolate from a gastric cancer patient and evaluated the influence of environmental pH on antibiotic efficacy.

Methods: The isolate was identified using the VITEK 2-Compact system, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), and 16S ribosomal ribonucleic acid (16S rRNA) sequencing. Antimicrobial susceptibility testing against 24 antibiotics was performed using the VITEK 2 system according to Clinical and Laboratory Standards Institute (CLSI) M100 (Ed33) guidelines. Resistance genes were detected by polymerase chain reaction (PCR) and sequencing. The impact of pH (5.5-8.5) on antibiotic activity was assessed using disk diffusion. In vivo efficacy of minocycline was evaluated in a murine urinary tract infection model with controlled urine pH modulation.

Results: The isolate showed 100% sequence identity with M. odoratimimus PR63069 and exhibited multidrug resistance, remaining susceptible only to minocycline. Molecular analysis confirmed the presence of the β-lactamase gene (blaMUS-1). Tigecycline and minocycline demonstrated optimal activity under neutral conditions (pH 7.3), whereas piperacillin-tazobactam showed relatively improved activity at alkaline pH. In vivo, urinary alkalization (pH 8.5) significantly enhanced the antibacterial efficacy of minocycline.

Conclusion: M. odoratimimus isolated from a gastric cancer patient demonstrated multidrug resistance mediated by blaMUS-1. Antibiotic activity varied with pH, and urine alkalinization improved minocycline efficacy, suggesting potential strategies for clinical management of Myroides infections.

Keywords: Myroides odoratimimus; antibiotic resistance gene; antibiotic susceptibility testing; multidrug resistance; pH value; urinary tract infection.

Publication types

  • Review
  • Case Reports

MeSH terms

  • Animals
  • Anti-Bacterial Agents* / pharmacology
  • Anti-Bacterial Agents* / therapeutic use
  • DNA, Bacterial / chemistry
  • DNA, Bacterial / genetics
  • DNA, Ribosomal / chemistry
  • DNA, Ribosomal / genetics
  • Disease Models, Animal
  • Drug Resistance, Bacterial*
  • Flavobacteriaceae Infections* / diagnosis
  • Flavobacteriaceae Infections* / drug therapy
  • Flavobacteriaceae Infections* / microbiology
  • Flavobacteriaceae* / drug effects
  • Flavobacteriaceae* / genetics
  • Flavobacteriaceae* / isolation & purification
  • Humans
  • Hydrogen-Ion Concentration
  • Male
  • Mice
  • Microbial Sensitivity Tests
  • Minocycline / pharmacology
  • Minocycline / therapeutic use
  • RNA, Ribosomal, 16S / genetics
  • Sequence Analysis, DNA
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
  • Stomach Neoplasms* / complications
  • Urinary Tract Infections / drug therapy
  • Urinary Tract Infections / microbiology

Substances

  • Anti-Bacterial Agents
  • RNA, Ribosomal, 16S
  • Minocycline
  • DNA, Ribosomal
  • DNA, Bacterial