A cluster of culture positive gonococcal infections but with false negative cppB gene based PCR.

OBJECTIVES: To describe the prevalence and characteristics of isolates of Neisseria gonorrhoeae grown from urine samples that produced negative results with nucleic acid amplification assays (NAA) targeting the cppB gene. METHODS: An initial cluster of culture positive, but cppB gene based NAA negative, gonococcal infections was recognised. Urine samples and suspensions of gonococci isolated over 9 months in the Northern Territory of Australia were examined using cppB gene based and other non-cppB gene based NAA. The gonococcal isolates were phenotyped by determining the auxotype/serovar (A/S) class and genotyped by pulsed field gel electrophoresis (PFGE). RESULTS: 14 (9.8%) of 143 gonococci isolated were of A/S class Pro(-/)Brpyut, indistinguishable on PFGE and negative in cppB gene based, but not other, NAA. CONCLUSIONS: This cluster represents a temporal and geographic expansion of a gonococcal subtype lacking the cppB gene with consequent loss of sensitivity of NAA dependent on amplification of this target. Gonococci lacking the cppB gene have in the past been more commonly associated with the PAU-/PCU- auxotype, a gonococcal subtype hitherto infrequently encountered in Australia. NAA based on the cppB gene as a target may produce false positive as well as false negative NAA. This suggests that unless there is continuing comparison with culture to show their utility, cppB gene based NAA should be regarded as suboptimal for use either as a diagnostic or supplemental assay for diagnosis of gonorrhoea, and NAA with alternative amplification targets should be substituted.

An outbreak of a penicillin-sensitive strain of gonorrhoea in Sydney men.

OBJECTIVE: To describe an outbreak of gonorrhoea caused by penicillin sensitive Wild type 1B2-Wt/1B2(FS), in homosexual men in Sydney. DESIGN AND SETTING: The study sample comprised all gonococcal isolates referred to the Gonococcal Reference Laboratory (GRL), New South Wales, Australia between 1 January 1990 and 30 June 1992. Demographic data on Wt/1B2(FS) were sought by review of all request forms accompanying specimens to the GRL. Detailed review was undertaken of the clinical records of all men with gonorrhoea which had been differentiated by auxotype and serotype (A/S) from two large STD clinics in Sydney. MEASUREMENTS AND MAIN RESULTS: The first isolation of Wt/1B2(FS) was made in April 1990 and by the end of July 1992, 140 such isolates were identified in 131 patients. The male:female ratio was 130:1 suggesting male homosexual transmission, which was confirmed in 55 of 57 evaluable cases. There was a higher proportion of pharyngeal and anal infections among Wt/1B2(FS) isolates compared with all other male gonorrhoea. Demographic information showed that 60% of men with Wt/1B2(FS) were under the age of 30, and 80% lived in Central or Eastern Sydney. CONCLUSIONS: An outbreak of a penicillin sensitive strain of gonorrhoea has occurred in Sydney, primarily among gay men living in the inner city. The extent to which the outbreak represents an increase in the risk of HIV transmission is unclear.

Maltose-negative Neisseria meningitidis isolated from a case of male urethritis.

A maltose-negative strain of Neisseria meningitidis isolated from a male patient with urethritis was initially identified as a gonococcus on the basis of carbohydrate utilization tests. Additional investigations initiated because of atypical colony morphology and a negative superoxol reaction showed the isolate to be a meningococcus with defective maltose-phosphorylating capacity.