Relevance of Citrobacter species in urinary tract infections: a 10 year surveillance study

Urinary tract infections are the third most common infections in human medicine worldwide. Citrobacter species present a challenge to both clinicians and clinical microbiologists, due to various intrinsic and acquired resistance mechanisms. This study includes microbiological and resistance data on urine samples positive for Citrobacter spp. between January 1, 2008 and December 31, 2017 at the Department of Clinical Microbiology, University of Szeged. Citrobacter species represented 0.7% (n=129) of outpatient samples and 0.6% (n=138) of inpatient samples. Their higher prevalence at advanced age (> 60 years) is consistent with that reported in the literature, whereas the clinical origin (inpatient/outpatient) of the urine specimens did not influence their isolation rates. Overall, the highest levels of resistance were observed with ceftriaxone (29.8% and 47.5%), whereas in case of gentamicin (8.3% and 25.4%) and fosfomycin (9.3 and 13.8%), the lowest level of resistance was detected, respectively. As these pathogens may cause nosocomial epidemics (usually in vulnerable patients groups), close and continuous monitoring is required at both institutional and national level.