Urogenital infection due to meningococcus in men and women

Emergence of a novel urogenital-tropic Neisseria meningitidis

PURPOSE OF REVIEW

Neisseria meningitidis (Nm) is primarily associated with asymptomatic nasopharyngeal carriage and invasive meningococcal disease (sepsis and meningitis), but like N. gonorrhoea (Ng), Nm can colonize urogenital and rectal mucosal surfaces and cause disease. First noted in 2015, but with origins in 2011, male urethritis clusters caused by a novel Nm clade were reported in the USA (the US_NmUC). This review describes research developments that characterize this urogenital-tropic Nm.

RECENT FINDINGS

The US_NmUC evolved from encapsulated Nm serogroup C strains. Loss of capsule expression, lipooligosaccharide (LOS) sialylation, genetic acquisition of gonococcal alleles (including the gonococcal anaerobic growth aniA/norB cassette), antimicrobial peptide heteroresistance and high surface expression of a unique factor-H-binding protein, can contribute to the urethra-tropic phenotype. Loss-of-function mutations in mtrC are overrepresented in clade isolates. Similar to Ng, repeat US_NmUC urethritis episodes can occur. The US_NmUC is now circulating in the UK and Southeast Asia. Genomic sequencing has defined the clade and rapid diagnostic tests are being developed for surveillance.

SUMMARY

The US_NmUC emerged as a cause of urethritis due to acquisition of gonococcal genetic determinants and phenotypic traits that facilitate urogenital tract infection. The epidemiology and pathogenesis of this urogenital-tropic pathogen continues to be defined.

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.

Heteroresistance to the model antimicrobial peptide polymyxin B in the emerging Neisseria meningitidis lineage 11.2 urethritis clade: mutations in the pilMNOPQ operon

Clusters of Neisseria meningitidis (Nm) urethritis among primarily heterosexual males in multiple US cities have been attributed to a unique non-encapsulated meningococcal clade (the US Nm urethritis clade, US_NmUC) within the hypervirulent clonal complex 11. Resistance to antimicrobial peptides (AMPs) is a key feature of urogenital pathogenesis of the closely related species, Neisseria gonorrhoeae. The US_NmUC isolates were found to be highly resistant to the model AMP, polymyxin B (PmB, MICs 64-256 µg ml^-1 ). The isolates also demonstrated stable subpopulations of heteroresistant colonies that showed near total resistant to PmB (MICs 384-1024 µg ml^-1 ) and colistin (MIC 256 µg ml^-1 ) as well as enhanced LL-37 resistance. This is the first observation of heteroresistance in N. meningitidis. Consistent with previous findings, overall PmB resistance in US_NmUC isolates was due to active Mtr efflux and LptA-mediated lipid A modification. However, whole genome sequencing, variant analyses and directed mutagenesis revealed that the heteroresistance phenotypes and very high-level AMP resistance were the result of point mutations and IS1655 element movement in the pilMNOPQ operon, encoding the type IV pilin biogenesis apparatus. Cross-resistance to other classes of antibiotics was also observed in the heteroresistant colonies. High-level resistance to AMPs may contribute to the pathogenesis of US_NmUC.

Emergence of a new Neisseria meningitidis clonal complex 11 lineage 11.2 clade as an effective urogenital pathogen

Neisseria meningitidis (Nm) clonal complex 11 (cc11) lineage is a hypervirulent pathogen responsible for outbreaks of invasive meningococcal disease, including among men who have sex with men, and is increasingly associated with urogenital infections. Recently, clusters of Nm urethritis have emerged primarily among heterosexual males in the United States. We determined that nonencapsulated meningococcal isolates from an ongoing Nm urethritis outbreak among epidemiologically unrelated men in Columbus, Ohio, are linked to increased Nm urethritis cases in multiple US cities, including Atlanta and Indianapolis, and that they form a unique clade (the US Nm urethritis clade, US_NmUC). The isolates belonged to the cc11 lineage 11.2/ET-15 with fine type of PorA P1.5-1, 10-8; FetA F3-6; PorB 2-2 and express a unique FHbp allele. A common molecular fingerprint of US_NmUC isolates was an IS1301 element in the intergenic region separating the capsule ctr-css operons and adjacent deletion of cssA/B/C and a part of csc, encoding the serogroup C capsule polymerase. This resulted in the loss of encapsulation and intrinsic lipooligosaccharide sialylation that may promote adherence to mucosal surfaces. Furthermore, we detected an IS1301-mediated inversion of an ∼20-kb sequence near the cps locus. Surprisingly, these isolates had acquired by gene conversion the complete gonococcal denitrification norB-aniA gene cassette, and strains grow well anaerobically. The cc11 US_NmUC isolates causing urethritis clusters in the United States may have adapted to a urogenital environment by loss of capsule and gene conversion of the Neisseria gonorrheae norB-aniA cassette promoting anaerobic growth.

Corynebacterium propinquum associated with acute, nongonococcal urethritis

Corynebacterium propinquum is usually considered part of the normal human oropharyngeal flora and is rarely responsible for clinical infection. We report here what seems to be the first case of acute purulent urethral discharge in a young Iranian man with urethritis acquired after orogenital contact. Attention should be devoted to less common nondiphtheriae Corynebacterium species for differential diagnosis.

Neisseria meningitidis urethritis: a case report highlighting clinical similarities to and epidemiological differences from gonococcal urethritis

An adult male presented to the Hawaii Health Department with a purulent urethral discharge. Urethral Gram stain examination led to a presumptive gonorrhea diagnosis even though his sexual history was nonsupportive. Culture results identified Neisseria meningitidis. This case report highlights the clinical similarities and differing epidemiology of these Neisseria urethritides.

An unusual cause of pelvic inflammatory disease due to Neisseria meningitidis

A case of pelvic inflammatory disease due to Neisseria meningitidis is described. The importance of the definitive diagnosis of Neisseria to a species level is underscored for public health issues, appropriate contact tracing, as well as potential psychosocial implications. A review of the literature of genitally related N. meningitidis cases is made.

Orogenital transmission of Neisseria meningitidis serogroup C confirmed by genotyping techniques

Urethritis caused by Neisseria meningitidis in heterosexual patients is presumed to occur via orogenital contact, but confirmation has not been possible in most cases. Presented here is a case of urethritis caused by N. meningitidis, serogroup C, and the isolation of the same microorganism from the nasopharynx and endocervix of the patient's sexual partner. The similarity of the urethral and nasopharyngeal isolates' electrophoretic patterns, obtained using pulsed-field gel electrophoresis, proves the infection was transmitted via orogenital contact.

An unusual transmission of Neisseria meningitidis: neonatal conjunctivitis acquired at delivery from the mother's endocervical infection

BACKGROUND

Primary meningococcal conjunctivitis is assumed to be due to the direct inoculation of Neisseria meningitidis into the conjunctival sac from an exogenous source. According to a literature review, no case of neonatal conjunctivitis infection acquired at delivery from maternal endocervicitis has been published.

GOAL

To report a case of meningococcal neonatal conjunctivitis acquired at delivery because of the mother's endocervical infection and cross-transmission of the strain with her partner.

STUDY DESIGN

Strains were characterized by bacteriologic and serologic methods including grouping (agglutination), typing, and subtyping (enzyme-linked immunoabsorbent assay). Molecular analysis was done by pulsed-field gel electrophoresis.

RESULTS

The three strains (newborn infant, mother, partner) were of the same antigenic formula (C:NT:P1.NT) and exhibited similar NheI and SpeI pulsed-field gel electrophoresis patterns.

CONCLUSION

The identical phenotypic and genomic analysis of strains is the evidence for N meningitidis transmission at delivery from a maternal endocervical infection to the newborn infant and cross transmission between sexual partners.

Etiology of nongonococcal nonchlamydial urethritis

The majority of cases of acute nongonococcal urethritis (NGU) are due to causes other than infection with Chlamydia trachomatis. Pathogens implicated as causes of nonchlamydial nongonococcal urethritis (NCNGU) include Mycoplasma genitalium, Ureaplasma urealyticum, Trichomonas vaginalis, and primary infection with herpes simplex virus. In a majority of cases of acute NCNGU, no pathogen can be isolated. The etiology of chronic NCNGU is unknown.

Oral sex and transmission of non-viral STIs

OBJECTIVES

To review the literature on the role of oral sex in the transmission of non-viral sexually transmitted infections (STIs).

METHOD

A Medline search was performed using the keywords oro-genital sex, and those specific to each infection. Further references were then taken from each article read.

CONCLUSIONS

Oral sex is a common sexual practice between both heterosexual and homosexual couples. Oro-genital sex is implicated as a route of transmission for gonorrhoea, syphilis, Chlamydia trachomatis, chancroid, and Neisseria meningitidis. Other respiratory organisms such as streptococci, Haemophilus influenzae, and Mycoplasma pneumoniae could also be transmitted by this route. Fellatio confers risk for acquisition of infection by the oral partner. Cunnilingus appears to predispose to recurrent vaginal candidiasis although the mechanism for this is unclear, while a link between oro-genital sex and bacterial vaginosis is currently being studied. Oro-anal sex is implicated in the transmission of various enteric infections. In view of the increased practice of oral sex this has become a more important potential route of transmission for oral, respiratory, and genital pathogens.

Nasopharyngeal flora in HIV seropositive men who have sex with men

OBJECTIVES

To assess, in men who were infected with the human immunodeficiency virus (HIV) and who identified themselves as having had sex with men; the nasopharyngeal prevalence of Neisseria gonorrhoeae, N meningitidis, Corynebacterium diphtheriae, and candida species; oral sexual behaviour; the relation between oral flora and oral sexual behavior.

METHOD

Nasopharyngeal swabs were taken from HIV seropositive men for culture. The men were also asked to complete a self administered questionnaire.

RESULTS

390 men were recruited; 286 (73.3%) provided nasopharyngeal samples and questionnaires; 41 (10.5%) provided nasopharyngeal samples only; 63 (16.2%) provided questionnaires only. From the 327 nasopharyngeal samples N meningitidis was cultured in 49 (15%) and candida species in 165 (50.5%). Cultures for N gonorrhoeae and C diphtheriae were all negative. Data from the 349 completed questionnaires indicated that 285 men were practising oro-penile sex, over 90% did not consistently use condoms; 150 men were practising oro-anal sex, one used dental dams. In those providing both nasopharyngeal samples and sexual behaviour data meningococcal carriage was identified in 40 (17.5%) of the 228 men practising receptive oro-penile sex, compared with one (2.3%) of the 43 non-practisers (p < 0.025); in 21 (20%) of the 105 men practising insertive oro-anal sex, compared with 17 (12.5%) of the 136 non-practisers (p = 0.12). No correlation was identified between yeast carriage and oro-genital sex.

CONCLUSION

Oro-genital sex, usually without barrier protection, is common among HIV infected men who have sex with men. It appears to be associated with increased meningococcal carriage but is autonomous to candida species isolation. Routine screening for nasopharyngeal N gonorrhoeae is not deemed necessary.

Pharyngeal flora in a sexually active population

During a 7-week period 1141 patients attending the Genitourinary Clinic at Charing Cross Hospital completed a brief questionnaire and had pharyngeal swabs cultured for Neisseria spp, beta-haemolytic streptococci, corynebacterium and yeasts. The study included 397 heterosexual men, 492 heterosexual women, 189 homosexuals, 41 lesbians and 22 bisexual men and women. Four hundred and sixty patients (40%) admitted oro-genital contact in the preceding 2 weeks. The meningococcal carriage rate was 11.6%. Homosexuals had the highest carriage 23.8% and heterosexual females the lowest 5.9%. Significant differences in carriage rates were found between homosexual and heterosexual men (P < 0.0001), heterosexual men and women (P < 0.005) and between lesbian and heterosexual women (P < 0.025). Recent oro-anal contact significantly increased meningococcal isolation (P < 0.001). A significant association between beta-haemolytic streptococci and concomitant meningococcal carriage was also found (P < 0.01). Sexual orientation and oro-genital contact influences both meningococcal and pharyngeal yeast isolation and should be considered when interpreting pharyngeal culture results.

Microevolution within a clonal population of pathogenic bacteria: recombination, gene duplication and horizontal genetic exchange in the opa gene family of Neisseria meningitidis

Opacity (Opa) proteins are a family of antigenically variable outer-membrane proteins of Neisseria meningitidis. Even among clonally related epidemic meningococcal isolates, there is greater variation of Opa protein expression than can be accounted for by the opa gene repertoire of any individual strain. We characterized the opa genes of eight closely related isolates of serogroup A N. meningitidis (subgroup IV-1) from a recent meningitis epidemic in West Africa. DNA sequence analysis and Southern blot experiments indicated that changes occurred in the opa genes of these bacteria as they spread through the human population, over a relatively short period of time. Such changes in one or a few loci within a clonal population are referred to as microevolution. The distribution of sequences present in hypervariable (HV) regions of the opa genes suggests that duplication of all or part of opa genes into other opa loci changed the repertoire of Opa proteins that could be expressed. Additional variability in this gene family appears to have been introduced by horizontal exchange of opa sequences from other meningococcal strains and from Neisseria gonorrhoeae. These results indicate that processes of recombination and genetic exchange contributed to variability in major surface antigens of this clonal population of pathogenic bacteria.

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.

Preliminary evaluation of the ligase chain reaction for specific detection of Neisseria gonorrhoeae

Rapid identification of Neisseria gonorrhoeae in clinical specimens is essential for effective control. Traditional culture requires a minimum of 24 h, and for some specimens harboring gonococci, the gonococci fail to grow or are misidentified. The recently described ligase chain reaction (LCR) is a highly specific and sensitive DNA amplification technique which was evaluated as an alternative to routine culture. Three LCR probe sets were used. Two of the probe sets were directed against the multi-copy Opa genes (Omp-II), while the third set was targeted against the multicopy Pilin genes. Each LCR probe set was evaluated with 260 microorganisms including 136 global isolates of N. gonorrhoeae, 41 isolates of N. meningitidis, and 10 isolates of N. lactamica; 26 nonpathogenic Neisseria strains; and 47 isolates of non-Neisseria species that may reside in clinical specimens. Amplification products were detected by using the IMx LCR format (Abbott Laboratories, Abbott Park, Ill.). Strains of N. gonorrhoeae were assayed at 270 cells per LCR (approximately 6.7 x 10(4) CFU/ml) with the Opa and Pilin probes, producing signals at least 21 and 15 times above background, respectively. In contrast, only background values were observed when testing the probe sets with 124 nongonococcal strains at 1.3 x 10(6) cells per LCR (approximately 3.2 x 10(8) CFU/ml). One hundred urogenital specimens were assayed by LCR, and compared with culture, the three probes were 100% sensitive (8 of 8) and 97.8% specific (90 of 92), resulting in an agreement of 98% (98 of 100). On the basis of the results of these preliminary studies, LCR has the potential to be an accurate and rapid DNA probe assay for the detection of N. gonorrhoeae in clinical specimens.

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.