Anogenital non-gonococcal neisseriae: prevalence and clinical significance

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.

Orogenital Transmission of Neisseria meningitidis Causing Acute Urethritis in Men Who Have Sex with Men

Neisseria meningitidis sequence type 11 is an emerging cause of urethritis. We demonstrate by using whole-genome sequencing orogenital transmission of a N. meningitidis sequence type 11 isolate causing urethritis in a monogamous couple of men who have sex with men. These results suggest dissemination of this clonal complex among low-risk patients.

Large Cluster of Neisseria meningitidis Urethritis in Columbus, Ohio, 2015

Background

Neisseria meningitidis (Nm) is a Gram-negative diplococcus that normally colonizes the nasopharynx and rarely infects the urogenital tract. On Gram stain of urethral exudates, Nm can be misidentified as the more common sexually transmitted pathogen Neisseria gonorrhoeae.

Methods

In response to a large increase in cases of Nm urethritis identified among men presenting for screening at a sexually transmitted disease clinic in Columbus, Ohio, we investigated the epidemiologic characteristics of men with Nm urethritis and the molecular and phylogenetic characteristics of their Nm isolates. The study was conducted between 1 January and 18 November 2015.

Results

Seventy-five Nm urethritis cases were confirmed by biochemical and polymerase chain reaction testing. Men with Nm urethritis were a median age of 31 years (interquartile range [IQR] = 24-38) and had a median of 2 sex partners in the last 3 months (IQR = 1-3). Nm cases were predominantly black (81%) and heterosexual (99%). Most had urethral discharge (91%), reported oral sex with a female in the last 12 months (96%), and were treated with a ceftriaxone-based regimen (95%). A minority (15%) also had urethral chlamydia coinfection. All urethral Nm isolates were nongroupable, ST-11 clonal complex (cc11), ET-15, and clustered together phylogenetically. Urethral Nm isolates were similar by fine typing (PorA P1.5-1,10-8, PorB 2-2, FetA F3-6), except 2, which had different PorB types (2-78 and 2-52).

Conclusions

Between January and November 2015, 75 urethritis cases due to a distinct Nm clade occurred among primarily black, heterosexual men in Columbus, Ohio. Future urogenital Nm infection studies should focus on pathogenesis and modes of sexual transmission.

Notes from the Field: Increase in Neisseria meningitidis-Associated Urethritis Among Men at Two Sentinel Clinics - Columbus, Ohio, and Oakland County, Michigan, 2015

Neisseria meningitidis (Nm) urogenital infections, although less common than infections caused by Neisseria gonorrhoeae (Ng), have been associated with urethritis, cervicitis, proctitis, and pelvic inflammatory disease. Nm can appear similar to Ng on Gram stain analysis (gram-negative intracellular diplococci) (1-5). Because Nm colonizes the nasopharynx, men who receive oral sex (fellatio) can acquire urethral Nm infections (1,3,5). This report describes an increase in Nm-associated urethritis in men attending sexual health clinics in Columbus, Ohio, and Oakland County, Michigan.

Fournier's Gangrene in a Heterosexual Man: A Complication of Neisseria meningitidis Urethritis

A 55-year-old heterosexual male presented to the emergency department with a symptomatology consistent with urethritis and Fournier's gangrene. Urethral swab and operative tissue cultures were positive for coagulase-negative Staphylococcus and an intracellular Gram-negative diplococcus. The latter was initially thought to be Neisseria gonorrhea; however, DNA sequencing technique confirmed it to be Neisseria meningitidis. The patient required three separate surgical debridements to control widespread necrotizing infection. Following documentation of sterile wound healing with appropriate antibiotics, four reconstructive surgeries were necessary to manage the resultant wound defects. To our knowledge, Neisseria meningitidis as a causative organism in Fournier's gangrene has not been reported in the literature.

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.

Vulvite à méningocoque chez une fillette impubère

Neisseria meningitidis is an uncommon cause of vulvovaginitis in the prepubertal girl. The microorganism must not be mistaken for Neisseria gonorrhoeae, as the consequences of such an error may be serious. Colonization or infection by Neisseria meningitis is not uncommon in adolescents and adults. Vulvitis, even when it is recurrent, is not per se a good indicator of sexual abuse, but some microorganisms found by vaginal swab can make it possible, likely or certain. Sexual transmission of N. meningitidis has not been described in the prepubertal child.

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.

[Up to date in sexually transmitted infections: epidemiology, diagnostic approaches and treatments]

In the last years, there have been important advances in sexually transmitted infections such as genome sequencing of Treponema pallidum, Chlamydia trachomatis or Mycoplasma genitalium; the new taxonomic position of Calymmatobacterium granulomatis; commercial diagnostic systems based on nucleic acid amplification; the emergence of quinolone resistance in Neisseria gonorrhoeae; new therapeutic approaches in vulvovaginal candidiasis that include boric acid; the demonstration that valacyclovir reduces the risk of transmission of genital herpes or the availability of immune-response modifier in the treatment of genital warts, and that are questions in the goal of this review. Viral hepatitis and HIV were no reviewed by space reasons.

Acute urethritis caused by Neisseria meningitidis

A 48-year-old heterosexual Japanese man visited the outpatient clinic of Nagoya Urology Hospital, complaining of burning pain at voiding and pus discharge from the urethral orifice. These symptoms appeared the day following oral-genital contact (fellatio) with a commercial sex worker. On the basis of the presumptive clinical diagnosis of gonorrhea because of the microscopic detection of diplococci in the urethral discharge, he was treated with levofloxacin (300 mg per day) for 7 days. His symptoms responded quickly and urinalysis taken 7 days later was normal. Microbiological examinations isolated Neisseria meningitidis in the urethral discharge by culture with the use of enzymatic profiles. Further prevalence of sexually transmitted diseases (STD) through oral-genital contact would lead to an increase in meningococcal urethritis.

A gonococcal porA pseudogene: implications for understanding the evolution and pathogenicity of Neisseria gonorrhoeae

Members of the genus Neisseria, including the human pathogens Neisseria meningitidis and Neisseria gonorrhoeae, express at least one member of a family of related porins. N. meningitidis is the only species known to express a second porin, the meningococcal serosubtyping antigen PorA, the most divergent member of this family. Unexpectedly, a porA gene was identified in the gonococcal genome. Both the gonococcal and meningococcal porA loci were adjacent to a homologue of the Escherichia coli greA gene, although the IS1106 element downstream of porA in some meningococci was absent in the gonococcus. Almost identical porA loci were present in four unrelated gonococcal isolates and clinical specimens from patients with gonorrhoea. Lack of PorA expression in the gonococcus resulted from mutations in the promoter region, which prevented transcription, and frameshift mutations in the coding region of the porA gene. Hybridization and amplification experiments, showing the absence of a porA gene in seven other Neisseria species, suggested that porA was acquired by a common ancestor of the gonococcus and meningococcus but inactivated in the gonococcus on speciation. This implies that, while advantageous during colonization of the upper respiratory tract, this protein has no function in, or hinders, colonization of the urogenital tract.

Neisseria meningitidis serogroup B peritonitis associated with continuous ambulatory peritoneal dialysis

A case of Neisseria meningitidis peritonitis in a 41-year-old female undergoing continuous ambulatory peritoneal dialysis for end-stage renal failure due to insulin-dependent diabetes mellitus is reported. The bacterial strain was serosubtyped as 4:P1.15, a rarely encountered type. Surprisingly, the minimal inhibitory concentration of vancomycin for the isolate was low (16 mg/l). This may have contributed to the complete recovery of the patient.

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.

Non-cultural detection of rectal and pharyngeal gonorrhoea by the Gen-Probe PACE 2 assay

OBJECTIVE

To assess the sensitivity and specificity of the Gen-Probe PACE 2 assay, which uses a chemiluminescent labelled single-stranded DNA probe to detect gonococcal ribosomal RNA (rRNA), for the non-cultural detection of rectal and pharyngeal gonorrhoea in homosexual men.

SUBJECTS

161 homosexual men attending the Department of Genitourinary Medicine, Edinburgh Royal Infirmary during the latter half of 1995 and the first quarter of 1996.

METHODS

Duplicate rectal and pharyngeal swabs were collected for culture on modified New York City (MNYC) medium and detection of gonococcal nucleic acid by the Gen-Probe assay. Repeatedly reactive Gen-Probe specimens from culture negative patients were also tested by the Gen-Probe competition assay (PCA).

RESULTS

Of the 161 patients, 23 (14.3%) gave a positive culture at one or both sites (rectum 10, throat 8, rectum and throat 5) compared with 28 (16.7%) who gave a positive Gen-Probe result at one or both sites (rectum 9, throat 11, rectum and throat 8). After resolution of discrepant results by PCA the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of Gen-Probe was 94.1%, 100%, 100% and 99.3% for rectal specimens while the corresponding values for pharyngeal specimens were 86.4%, 100%, 100%, and 97.9%. The sensitivity and NPV of rectal culture were 88.2% and 98.6% while the corresponding values for pharyngeal culture were 59% and 93.9%. Gen-Probe was significantly more sensitive than throat culture (p < 0.05) but not rectal culture (p > 0.2). The average Relative Light Units (RLU) value for the cut-off was 386 (range 351-450) while the average for a positive result was 20306 (range 403-110104): this was, however, significantly higher (p = 0.019) in rectal specimens 31325 (range 1705-110104) than in throat specimens 10447 (range 403-15633).

CONCLUSIONS

Gen-Probe PACE 2 assay is a sensitive and specific method for the detection of rectal and pharyngeal gonorrhoea. As the Gen-Probe assay may detect nucleic acid from non viable gonococci the clinical significance of a probe positive culture negative specimen from a patient without culture evidence of gonorrhoea at another site is uncertain and requires further consideration. Nevertheless a positive result does indicate exposure to infection and could be important in ensuring appropriate partner notification action. If non-cultural methods are used to screen for gonococcal infection cultures should be obtained from patients with positive results in order that the antibiotic susceptibility and molecular epidemiology of the gonococcal population can be monitored.