Clonal outbreak of Myroides odoratimimus in ICU patients: A descriptive analysis of pan-drug resistance and associated mortality

Myroides odoratimimus, a non-fermentative Gram-negative bacillus, has increasingly been recognized as a cause of opportunistic healthcare-associated infections, particularly in intensive care units (ICUs). Its intrinsic resistance to multiple antibiotic classes, including carbapenems, aminoglycosides, and polymyxins, presents serious therapeutic challenges. Here, we report a clonal outbreak of urinary M. odoratimimus involving 27 patients over a 7-month period in a tertiary care hospital in Turkey. All patients were hospitalized in ICUs and had indwelling urinary catheters. The isolates were identified using automated systems and confirmed through 16S rRNA gene sequencing. Clonal relatedness was determined by (GTG)₅-PCR, demonstrating genetic identity among all isolates despite their detection in different ICU wards. All strains exhibited a pan-drug-resistant phenotype, showing resistance to every tested antimicrobial, including colistin. The mean duration of hospital stay was 61 days, and the mortality rate was 70.3 %, notably exceeding predicted mortality based on APACHE II scores and the background ICU mortality rate. Environmental cultures were all negative, possibly due to delayed sampling or limitations of conventional detection techniques. This study highlights the ability of M. odoratimimus to cause persistent clonal outbreaks in critical care settings, underscores its clinical significance as a multidrug-resistant pathogen, and emphasizes the need for early microbiological identification, molecular surveillance, and robust infection control strategies.