Incidence of the Extra-intestinal Pathogenic <i>Escherichia coli</i> (ExPEC) Infections within University Hospital population

This study estimated the incidence of extraintestinal pathogenic Escherichia coli (E. coli; ExPEC) infections at Kyushu University Hospital from 2013-2018, analyzing 63,041 hospitalized and 178,690 outpatients aged ≥20 years. ExPEC infections were defined as E. coli detection in sterile specimens or urine specimens (≥103 CFU/mL) with increased SOFA scores or urological infection diagnosis codes. The incidence rate was substantially higher in hospitalized patients (1,209.3 per 100,000 person-years) compared to outpatients (94.5 per 100,000 person-years), with females showing slightly higher rates in both groups. Age was a significant risk factor, with incidence rates increasing markedly in patients ≥60 years (inpatients: 1,431.6; outpatients: 125.3 per 100,000 person-years). Importantly, the study revealed that relying solely on diagnostic names underestimated the true number of ExPEC infection cases. The precision rate, defined as the proportion of cases (n=61) with both E. coli isolated and clinically inflammatory symptoms who received an infectious disease diagnosis (n=46), was at most 75% in female outpatients. It is suggested that comprehensive microbiological data combined with clinical criteria provides more accurate surveillance. These findings establish baseline incidence rates for ExPEC infections in a Japanese hospital setting and highlight the clinical significance of these infections, particularly in elderly hospitalized patients.