Urinary tract infection with Corynebacterium urealyticum in South Africa

Corynebacterium urealyticum has been well documented as a urinary pathogen in Europe. The purpose of this study was to investigate the incidence and clinical relevance of Corynebacterium urealyticum as a urinary pathogen in a predominantly Third World population (South Africa) and to attempt to increase the isolation rate by culturing urine specimens on a selective medium. Two methods were used to isolate Corynebacterium urealyticum from urine specimens. Blood agar plates from routine urine cultures of 7,912 urine specimens were incubated for 48 hours and 1,281 specimens were cultured on a selective medium as well as on routine media. The antimicrobial susceptibility of all isolates of Corynebacterium urealyticum was tested. The yield of Corynebacterium urealyticum on blood agar was three isolates in three patients (0.038% of 7,912), all of whom had pyuria, alkaline urine and risk factors for Corynebacterium urealyticum infection. Use of selective media increased the yield of Corynebacterium urealyticum to 15 of 1,281 specimens (1.17%), however 73% of these urine samples yielded other pathogens and none had an alkaline pH which could not be attributed to the presence of another urealytic pathogen. All isolates were susceptible to vancomycin and 92.6% susceptible to norfloxacin. The pathogenic potential of Corynebacterium urealyticum was confirmed in South African patients, but the incidence of infection was low. The use of a selective medium is therefore not cost-effective in all cases but could be used selectively on the basis of typical urine findings and patient criteria.