Serogropus of escherichia coli in symptomatic and asymptomatic urinary tract infections in Christchurch.

525 isolates of E. coli were obtained from the urine of patients during episodes of urinary tract infection (UTI). Of these, 250 cultures were from asymptomatic patients, detected during screening of adolescent or pregnant women. The remaining 275 cultures were from patients who attended general practitioners with symptoms of UTI. When isolates were typed using commercial urinary E. coli O antisera, 39.2% from asymptomatic UTI and 32.4% from symptomatic UTI were non-typable. There were 29.2% autoagglutinating isolates from asymptomatic and 14.5% from symptomatic UTI. The most frequently isolated O serogroups were O6, O75 and O18. Numbers of O6 and O75 were higher in symptomatic UTI than asymptomatic: 20% and 15.3% compared with 8.8% and 7.2%. Distribution of other serogroups was similar for both series. Therefore the most striking differences were the greater number of autoagglutinating organisms in asymptomatic UTI and of O6 and O75 serogroups in symptomatic UTI.