Gonorrhoea culture is required to monitor antibiotic resistance and is recommended for all patients known or suspected to be infected. In July 2016 a retrospective comparison of near-patient direct plating and transported charcoal swabs found that the culture positive rate was 24% lower for charcoal swabs. Since this audit, the laboratory service implemented an urgent transport system for charcoal swabs, in order to improve the reliability of this method.Methods
Between July 2016 and January 2017 all patients who had a positive GC NAAT or were otherwise at high risk had two culture swab specimens taken from the infected site (cervical, male urethra, rectum, pharynx): 1. a charcoal swab sent to the laboratory for plating within two hours and 2. specimen directly plated onto VCAT GC selective agar.Results
Of 139 positive NAATs across all sites, 47 were followed by both direct plating and charcoal swab. Of these 47 pairs of cultures, there were only 2 discrepancies between culture types (one with direct plating positive, charcoal negative, the other vice-versa).Discussion
With the implementation of the new urgent transport system, there is no difference in the culture positive rates of direct plating versus charcoal swabs for GC culture. Provided the same high standards of transport are maintained, a change in practice, moving to charcoal swabs transported to the lab for GC culture and stopping direct plating, is recommended.