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

Meningococcal disease and sexual transmission: urogenital and anorectal infections and invasive disease due to Neisseria meningitidis

Neisseria meningitidis is an obligate human commensal bacterium that frequently colonises the upper respiratory tract. Person-to-person transmission occurs via direct contact or through dispersion of respiratory droplets from a carrier of the bacteria, and can lead to invasive meningococcal disease. Rare sporadic cases of meningococcal urogenital and anorectal infections, including urethritis, proctitis, and cervicitis, have been reported, typically following orogenital contact with an oropharyngeal meningococcal carrier. The resulting infections were clinically indistinguishable from infections caused by Neisseria gonorrhoeae. Over the past two decades, there have also been multiple outbreaks across North America and Europe of invasive meningococcal disease among men who have sex with men (MSM). The responsible meningococci belong to a highly virulent and predominantly serogroup C lineage, including strains that are able to express nitrite reductase and grow in anaerobic environments, such as the urogenital and anorectal tracts. More recently, a distinct clade within this lineage has expanded to cause urethritis predominantly among men who have sex with women. Evolutionary events giving rise to this clade included the loss of the ability to express a capsule, and acquisition of several gonococcal alleles, including one allele encoding a highly efficient gonococcal nitrite reductase. Members of the clade continue to acquire gonococcal alleles, including one allele associated with decreased antibiotic susceptibility. This evolution has implications for the clinical and public health management of those who are infected and their close contacts, in terms of both antibiotic treatment, and prevention through vaccination.

Molecular tests can allow confirmation of invasive meningococcal disease when isolates yield atypical maltose, glucose or gamma-glutamyl peptidase test results

Analysis of atypical meningococci from invasive disease that either (i) did not produce acid from maltose and glucose or (ii) were gamma-glutamyl peptidase test negative for porA and porB DNA variable region (VR) type, multilocus sequence type, and for presence of capsule transport gene ctrA, conclusively demonstrated that these are Neisseria meningitidis.

Anogenital non-gonococcal neisseriae: prevalence and clinical significance

Over a 13-year period non-gonococcal neisseriae (NGN) were isolated from 114 of 88,670 patients (0.13%) screened for anogenital gonorrhoea at a Genitourinary Medicine Unit. During the same period there were approximately 9000 anogenital gonococcal infections (10%). The prevalence of NGN was 0.09% (27/31,500) in women, 0.04% (20/52,800) in heterosexual men and 1.5% (67/4370) in homosexual men: the differences in prevalence between women and heterosexual men (P < 0.01) and between heterosexual patients and homosexual men (P < 0.001) are highly significant. Neisseria meningitidis was isolated most frequently and accounted for 85% (99/114) of the NGN. Whenever possible, N. meningitidis was serogrouped and its occurrence correlated with patient symptoms. Eleven of 18 heterosexual men who had meningococci isolated from their urethras had urethritis but co-existing chlamydial infection was excluded in only 5. None of 9 women with cervical colonization had clinical evidence of pelvic inflammation. Only one of 49 men with rectal colonization had proctitis. The management of anogenital NGN infection is discussed in relation to our findings and those of previously published studies. Within each patient group the prevalence and incidence of anogenital NGN were similar at the beginning and end of the study period indicating that levels have not been influenced by the advent of AIDS.

Urethritis due to Neisseria meningitidis in a London genitourinary medicine clinic population

A retrospective study was performed in a department of genitourinary medicine to determine the prevalence and clinical features of urethral and cervical infection with Neisseria meningitidis among patients being screened for sexually transmitted diseases. During the 28 month period of the study 11 isolates (from 10 patients) of N. meningitidis were identified from 5571 urethral cultures from homosexual men (0.2%). This compares with an isolation rate of 4.7% for N. gonorrhoeae; 1.2% samples screened for chlamydial antigen were positive. There were no isolates from 8992 urethral cultures from heterosexual men or 15,976 cervical cultures. Eight of the cases identified had features of urethritis at diagnosis; 6 were diagnosed initially as non-specific urethritis (NSU) and 2 as gonorrhoea on the basis of microscopy of a urethral smear. Eight of the 10 patients were treated with amoxycillin and/or a tetracycline, and all but one had a clinical and microbiological cure. In the study population the prevalence of N. meningitidis infection was low and restricted to homosexual men; however, it may be associated with symptoms.