Meningococcal colonisation misdiagnosed as gonococcal pharyngeal infection.

Abstract

SUMMARY Three cases of pharyngeal gonorrhoea were misdiagnosed in patients harbouring meningococci which failed to utilise maltose in CTA medium. The microbiological identity of the isolates was established by other means. Although meningococci giving atypical reactions to carbohydrate utilisation tests occur only rarely, the possibility of a misdiagnosis of gonorrhoea, and its social and legal repercussions, should be considered.

Superoxol and amylase inhibition tests for distinguishing gonococcal and nongonococcal cultures growing on selective media

“…negative by carbohydrate utilization tests (7) and were part of a group of N. gonorrhoeae cultures provided to the Centers for Disease Control by state health laboratories as "problem" cultures (1). Ten N. gonorrhoeae strains were vancomycin sensitive and grew poorly on selective modified Thayer-Martin medium (MTM) (13).…”

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

“…Strains of meningococci are infrequently isolated from the genital tract. Maltose-negative meningococci, too, are occasionally reported from various clinical sites (5,10,11). Our strain caused initial confusion because of its site of isolation and its inability to utilize maltose.…”

Identification of problem Neisseria gonorrhoeae cultures by standard and experimental tests

“…New rapid tests for confirming and identifying Neisseria isolates as to species are now available and have the potential for improving the proficiency of clinical laboratories. However, false positivity in the Phadebact co-agglutination test (5) with some Neisseria lactamica strains (1) and cross-reactivity in the experimental rough-lipopolysaccharide (R-LPS) and wheat germ agglutination tests (12,16) with some N. meningitidis strains (8) require caution in interpreting results, especially when testing pharyngeal isolates (10).…”