Our aim was to determine the number of chlamydial infections detected by Cobas Amplicor CT/NG multiplex polymerase chain reaction (PCR) testing of genital and first-voided urine (FVU) specimens compared with routine culture. Two hundred and eighty-six female and 276 male patients attending the Genito-Urinary Medicine (GUM) Unit at Edinburgh Royal Infirmary were included in the study. Case notes were analysed retrospectively to determine how many infected patients would not have been treated had diagnosis relied on routine culture.
Polymerase chain reaction on FVU from women had a sensitivity, specificity, positive and negative predictive value of 91%, 100%, 100% and 99.1%: corresponding values for genital PCR and culture were 96%, 100%, 100%, 99.6% and 65%, 100%, 100%, 96.7% respectively. PCR on FVU from men had a sensitivity, specificity, positive and negative predictive value of 96%, 99.1%, 92.6% and 99.5%: corresponding values for genital PCR and culture were 89%, 99.5%, 95.8%, 98.6% and 48%, 100%, 100%, 94.3% respectively.
In both men and women genital PCR and urine PCR were significantly more sensitive than culture. PCR almost doubled the number of patients detected by culture (49 vs 27). Of the 22 cases detected only by PCR 8 would not have received treatment on the basis of clinic treatment policy.