Catheter associated urinary tract infections due to Trichosporon asahii

Abstract

Urinary tract infections (UTIs) caused by fungi, frequently associated with medical devices, have increased and caused great morbidity and mortality among hospitalized patients. Difficulties on different species identification as well as the lack of standardized sensitivity tests in vitro, contribute to the limited information available on epidemiology, diagnosis, and therapeutics of Trichosporon infections. There are only sporadic reports of UTI caused by Trichosporon asahii reported from India. We report six cases of UTI caused by T. asahii in severely ill patients in a tertiary care setup. Among six positive T. asahii UTI, four were found in female patients with a mean age of 60 years. We observed that all patients were on indwelling urinary catheter, broad-spectrum antibiotics, and with other comorbid conditions. With regard to the antifungal susceptibility testing, all the isolates were resistant to amphotericin B and sensitive to voriconazole. Majority of them were sensitive to Itraconazole, half of them were sensitive to fluconazole. The ubiquity and biofilm formation poses difficulty in establishing pathogenicity and delineating environmental or nosocomial infections. Risk factors such as use of antibiotics, indwelling catheter, and comorbidities such as hypertension, diabetes, anemia, and chronic kidney disease predispose for the development of UTI by T. asahii. Isolation of the same yeast in three consecutive urine samples with significant counts, along with significant number of pus cells establishes T. asahii as an etiological agent of UTI. Furthermore, the clearance of the fungus from the urinary tract with the recovery of the patient following catheter removal and antifungal therapy further confirms T. asahii as the cause of UTI.

Keywords: Nosocomial urinary tract infections; Trichosporon asahii; UTI's.

Figure 1

Tiny white, dry colonies on blood agar

Figure 2

Blue, dry wrinkled, colonies on urichrom agar with a colony count of >10⁵ CFU/ml after 24 h incubation at 37°C

Figure 3

Grams stain of the colony showing hyphal forms with arthrospores and few budding yeast cells

Figure 4

Corn meal agar showing pseudohyphae with blastoconidia of varying sizes and rectangular arthroconidia

Figure 5

Sabourauds dextrose broth showing pellicle formation and urease test positive

Figure 6

Sugar assimilation test showing assimilation of dextrose, maltose, sucrose, galactose, and lactose sugars

Figure 7

Antibiotic susceptibility testing on Mueller-Hinton Agar with 2% glucose and methylene blue showing semiconfluent growth of the test isolate

Figure 8

Wet mount of urine showing budding yeast cells, pseudohyphae and true hyphal forms