Development of a SimpleProbe real-Time PCR Assay for rapid detection and identification of the US novel urethrotropic clade of Neisseria meningitidis ST-11 (US_NmUC)

Sexual behavior shapes male genitourinary microbiome composition

The origin, composition, and significance of the distal male urethral microbiome are unclear, but vaginal microbiome dysbiosis is linked to new sex partners and several urogynecological syndromes. We characterized 110 urethral specimens from men without urethral symptoms, infections, or inflammation using shotgun metagenomics. Most urethral specimens contain characteristic lactic acid bacteria and Corynebacterium spp. In contrast, several bacteria associated with vaginal dysbiosis were present only in specimens from men who reported vaginal intercourse. Sexual behavior, but not other evaluated behavioral, demographic, or clinical variables, strongly associated with inter-specimen variance in urethral microbiome composition. Thus, the male urethra supports a simple core microbiome that is established independent of sexual exposures but can be re-shaped by vaginal sex. Overall, the results suggest that urogenital microbiology and sexual behavior are inexorably intertwined, and show that the male urethra harbors female urogenital pathobionts.

Meningococcal Urethritis: Old and New

Neisseria meningitidis is a common commensal bacterium found in the respiratory tract, but it can also cause severe, invasive disease. Vaccines have been employed which have been successful in helping to prevent invasive disease caused by encapsulated N. meningitidis from the A, C, W, Y, and B serogroups. Currently, nonencapsulated N. meningitidis groups are more common commensals in the population than in the prevaccine era. One emerging nonencapsulated group of bacteria is the U.S. N. meningitidis urethritis clade (US_NmUC), which can cause meningococcal urethritis in men. US_NmUC has unique genotypic and phenotypic features that may increase its fitness in the male urethra. It is diagnostically challenging to identify and distinguish meningococcal urethritis from Neisseria gonorrhoeae, as the clinical presentation and microbiological findings are overlapping. In this review, the history of meningococcal urethritis, emergence of US_NmUC, laboratory diagnosis, and clinical treatment are all explored.

Corynebacterium glucuronolyticum in men with and without urethritis syndrome: An underrecognized pathogen or a bona fide commensal?

BACKGROUND

By analysing the largest collection of Corynebacterium glucuronolyticum (C. glucuronolyticum) isolates from a single centre thus far, we aimed to appraise a potential causal link between an infrequently isolated species and the urethritis syndrome in men.

METHODS

A total of 1055 Caucasian male individuals with or without urethritis syndrome were included in this single-centre case-control study. Group-wise comparisons were pursued by analysing sociodemographic, behavioural and microbiological specificities between the two groups. C. glucuronolyticum isolates from urethral specimens were identified using the analytical profile index biotyping system (API Coryne) and additionally confirmed by MALDI-TOF mass-spectrometry, with subsequent determination of their antimicrobial sensitivity profiles. Statistical significance was set at p < 0.05 (two-tailed).

RESULTS

C. glucuronolyticum was isolated in 5.08% of study participants with urethritis syndrome and 3.60% of those without it (p = 0.303). In the urethritis group, the species was more frequently found as a sole isolate (p = 0.041) and after prior infection with Chlamydia trachomatis (p = 0.025). The most frequent presentation of urethritis included a clear discharge in small or moderate amounts, without any pathognomonic findings. The resistance rates were 62.22% for clindamycin, 42.22% for tetracycline and 26.67% for ciprofloxacin.

CONCLUSIONS

Our study provides major insights on the relevance of urethral C. glucuronolyticum in non-gonococcal urethritis, with significant implications for further aetiological research and management approaches.

Evaluation of Urethrotropic-Clade Meningococcal Infection by Urine Metagenomic Shotgun Sequencing

Urethral infections caused by an emerging nongroupable (NG) urethrotropic clade of Neisseria meningitidis were first reported in the United States in 2015 (the "U.S. NmNG urethritis clade"). Here, we evaluate for the presence of other urethral pathogens in men with U.S. NmNG urethritis clade infection. We evaluated 129 urine specimens collected from men at a sexual health clinic, including 33 from patients with culture-confirmed or suspected urethral N. meningitidis infection and 96 specimens in which nucleic acid amplification test detected Neisseria gonorrhoeae, Chlamydia trachomatis, both pathogens, or neither pathogen. N. meningitidis was detected first by real-time PCR, followed by metagenomic shotgun sequencing of 91 specimens to identify coinfections. N. meningitidis genomes were sequenced following selective whole-genome amplification when possible. Metagenomic sequencing detected N. meningitidis in 16 of 17 specimens from culture-confirmed N. meningitidis cases, with no coinfection by other conventional urethral pathogens. Metagenomic sequencing also detected N. meningitidis in three C. trachomatis-positive specimens, one specimen positive for both N. gonorrhoeae and C. trachomatis, and nine specimens with negative N. gonorrhoeae and C. trachomatis results, eight of which had suspected Neisseria infections. N. meningitidis from culture-confirmed N. meningitidis cases belonged to the U.S. NmNG urethritis clade, while N. meningitidis identified in other specimens belonged to multiple clonal complexes. Additional urethral pathogens were predominant in non-N. meningitidis specimens, including N. gonorrhoeae, C. trachomatis, Mycoplasma genitalium, Ureaplasma urealyticum, and herpes simplex virus 2. Coinfection with other conventional urethral pathogens is rare in men with culture-confirmed U.S. NmNG urethritis clade infection and points to the strong association of this clade with disease.

Ninhydrin as a novel DNA hybridization indicator applied to a highly reusable electrochemical genosensor for Candida auris

This work reports a simple strategy for Candida auris genomic DNA (gDNA) detection, a multi-resistant fungus associated with nosocomial outbreaks in healthcare settings, presenting high mortality and morbidity rates. The platform was developed using gold electrode sensitized with specific DNA capture probe and ninhydrin as a novel DNA hybridization indicator. The genosensor was able to detect C. auris in urine sample by differential pulse voltammetry and electrochemical impedance spectroscopy. The biosensor's analytical performance was evaluated by differential pulse voltammetry, detecting up to 4.5 pg μL^-1 of C. auris gDNA in urine (1:10, V/V). Moreover, the genosensor was reused eight times with no loss in the current signal response. The genosensor showed selectivity and stability, maintaining 100% of its response up to 80 days of storage. In order to analyze interactions of single and double-stranded DNA with ninhydrin, SEM, AFM and molecular dynamics studies followed by docking simulations were performed. Theoretical calculations showed ninhydrin interactions more favorably with dsDNA in an A-T rich binding pocket rather than with the ssDNA. Therefore, the proposed system is a promising electrochemical detection device towards a more accurate detection of C. auris gDNA in biological samples.

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.