Background This service is located in a large district general hospital bordering a large UK city. It was noticed over a short period that there were several discrepant results returned for detection of Neisseria gonorrhoeae (GC) using PCR technologies and traditional culture.
Aim We performed a 3-month look back at all samples sent for GC detection, in order to define local incidence of GC and discrepant results.
Methods All samples sent over the preceding 3 months from this service, either as local testing or as part of the national programme, were identified using computer records and then recorded into an excel spreadsheet for comparisons (see abstract P42 table 1).
Results 1245 cases were identified during the 3-month period. The total number of cases with at least one positive GC result from culture and PCR was 41 (3.29% of tested). 902 patients (72.5% of those tested) had samples sent for culture. Culture was on vancomycin-colistin-nystatin-trimethoprim enriched agar. 24 (2.7%) were reported positive for GC. There was a total of 1225 PCR based tests collected between the local and national programmes (98.4% of all cases). Abstract P42 Table 1 shows the specific methods of these two programmes. Of the 1225, 39 tests were positive (3%). All cases with a positive result were then further analysed. 27 had concordant results, that is, either the culture and PCR matched, or only one of the two tests was performed. This gave 14 patients with discordant results (1.1% of all tested, 34% of all positive results). 13 cases had a positive PCR but negative culture (93%), and one patient had a positive culture but negative PCR.
Discussion The overall numbers are too low for accurate statistical analysis, but our incidence of GC is around 3%. PCR detected many more cases than culture would alone, although there was a single case of culture positive and PCR negative. We plan to perform a 1-year analysis to obtain sufficient cases for statistical analysis.