Commensal Neisseria Research Articles

Outbreak or illusion: consequences of 'improved' diagnostics for gonorrhoea.

The sexual health service in Oxford introduced gonorrhoea nucleic amplification acid testing using the BD Viper XTR™ System. For practical reasons, a confirmatory nucleic amplification acid testing using a different platform was not used initially. Following the introduction of nucleic amplification acid testing, the rates of gonorrhoea increased threefold. Concerns were raised that this increase represented an outbreak. A retrospective review of cases over six months suggested that there may have been a number of false-positive results. A prospective study was then undertaken over six months, where all gonorrhoea positive samples were sent for confirmatory testing. This evaluation of all gonorrhoea cases in an English county found that the overall presumptive false-positive rates for gonorrhoea nucleic amplification acid testing using BD Viper XTR™ in our population are significant at 27% of female samples, 13.2% of heterosexual male samples, 3.5% of anogenital multiple site men who have sex with men samples and 62.8% of pharyngeal only men who have sex with men samples. The data demonstrate the need for confirmatory testing using a second nucleic acid target, as per BASHH/Public Health England guidelines, especially in low-prevalence settings and extragenital sites, due to cross-reactivity with commensal Neisseria species and low positive predictive values.

Multiplex Real-Time PCR Assay with High-Resolution Melting Analysis for Characterization of Antimicrobial Resistance in Neisseria gonorrhoeae.

Resistance to antibiotics used against Neisseria gonorrhoeae infections is a major public health concern. Antimicrobial resistance (AMR) testing relies on time-consuming culture-based methods. Development of rapid molecular tests for detection of AMR determinants could provide valuable tools for surveillance and epidemiological studies and for informing individual case management. We developed a fast (<1.5-h) SYBR green-based real-time PCR method with high-resolution melting (HRM) analysis. One triplex and three duplex reactions included two sequences for N. gonorrhoeae identification and seven determinants of resistance to extended-spectrum cephalosporins (ESCs), azithromycin, ciprofloxacin, and spectinomycin. The method was validated by testing 39 previously fully characterized N. gonorrhoeae strains, 19 commensal Neisseria species strains, and an additional panel of 193 gonococcal isolates. Results were compared with results of culture-based AMR determination. The assay correctly identified N. gonorrhoeae and the presence or absence of the seven AMR determinants. There was some cross-reactivity with nongonococcal Neisseria species, and the detection limit was 10(3) to 10(4) genomic DNA (gDNA) copies/reaction. Overall, the platform accurately detected resistance to ciprofloxacin (sensitivity and specificity, 100%), ceftriaxone (sensitivity, 100%; specificity, 90%), cefixime (sensitivity, 92%; specificity, 94%), azithromycin (sensitivity and specificity, 100%), and spectinomycin (sensitivity and specificity, 100%). In conclusion, our methodology accurately detects mutations that generate resistance to antibiotics used to treat gonorrhea. Low assay sensitivity prevents direct diagnostic testing of clinical specimens, but this method can be used to screen collections of gonococcal isolates for AMR more quickly than current culture-based AMR testing.

NeisseriaBase: a specialised Neisseria genomic resource and analysis platform.

Background. The gram-negative Neisseria is associated with two of the most potent human epidemic diseases: meningococcal meningitis and gonorrhoea. In both cases, disease is caused by bacteria colonizing human mucosal membrane surfaces. Overall, the genus shows great diversity and genetic variation mainly due to its ability to acquire and incorporate genetic material from a diverse range of sources through horizontal gene transfer. Although a number of databases exist for the Neisseria genomes, they are mostly focused on the pathogenic species. In this present study we present the freely available NeisseriaBase, a database dedicated to the genus Neisseria encompassing the complete and draft genomes of 15 pathogenic and commensal Neisseria species.Methods. The genomic data were retrieved from National Center for Biotechnology Information (NCBI) and annotated using the RAST server which were then stored into the MySQL database. The protein-coding genes were further analyzed to obtain information such as calculation of GC content (%), predicted hydrophobicity and molecular weight (Da) using in-house Perl scripts. The web application was developed following the secure four-tier web application architecture: (1) client workstation, (2) web server, (3) application server, and (4) database server. The web interface was constructed using PHP, JavaScript, jQuery, AJAX and CSS, utilizing the model-view-controller (MVC) framework. The in-house developed bioinformatics tools implemented in NeisseraBase were developed using Python, Perl, BioPerl and R languages.Results. Currently, NeisseriaBase houses 603,500 Coding Sequences (CDSs), 16,071 RNAs and 13,119 tRNA genes from 227 Neisseria genomes. The database is equipped with interactive web interfaces. Incorporation of the JBrowse genome browser in the database enables fast and smooth browsing of Neisseria genomes. NeisseriaBase includes the standard BLAST program to facilitate homology searching, and for Virulence Factor Database (VFDB) specific homology searches, the VFDB BLAST is also incorporated into the database. In addition, NeisseriaBase is equipped with in-house designed tools such as the Pairwise Genome Comparison tool (PGC) for comparative genomic analysis and the Pathogenomics Profiling Tool (PathoProT) for the comparative pathogenomics analysis of Neisseria strains.Discussion. This user-friendly database not only provides access to a host of genomic resources on Neisseria but also enables high-quality comparative genome analysis, which is crucial for the expanding scientific community interested in Neisseria research. This database is freely available at http://neisseria.um.edu.my.

Fructose-1,6-bisphosphate aldolase of Neisseria meningitidis binds human plasminogen via its C-terminal lysine residue.

Neisseria meningitidis is a leading cause of fatal sepsis and meningitis worldwide. As for commensal species of human neisseriae, N. meningitidis inhabits the human nasopharynx and asymptomatic colonization is ubiquitous. Only rarely does the organism invade and survive in the bloodstream leading to disease. Moonlighting proteins perform two or more autonomous, often dissimilar, functions using a single polypeptide chain. They have been increasingly reported on the surface of both prokaryotic and eukaryotic organisms and shown to interact with a variety of host ligands. In some organisms moonlighting proteins perform virulence‐related functions, and they may play a role in the pathogenesis of N. meningitidis. Fructose‐1,6‐bisphosphate aldolase (FBA) was previously shown to be surface‐exposed in meningococci and involved in adhesion to host cells. In this study, FBA was shown to be present on the surface of both pathogenic and commensal neisseriae, and surface localization and anchoring was demonstrated to be independent of aldolase activity. Importantly, meningococcal FBA was found to bind to human glu‐plasminogen in a dose‐dependent manner. Site‐directed mutagenesis demonstrated that the C‐terminal lysine residue of FBA was required for this interaction, whereas subterminal lysine residues were not involved.

Molecular tests for the detection of antimicrobial resistant Neisseria gonorrhoeae: when, where, and how to use?

Molecular methods for the diagnosis of Neisseria gonorrhoeae are replacing bacterial culture in many settings. This review focuses on recent progress in the development of molecular tests to detect resistant N. gonorrhoeae both to enhance surveillance and to guide decisions about individual patient management. Assays to enhance surveillance have been developed to detect determinants of resistance for all antibiotics used as first-line gonorrhoea treatment, or to detect specific 'superbug' strains, but few have been applied in clinical practice. The most advanced strategy relevant to individual case management is to identify ciprofloxacin-sensitive strains so that unnecessary use of ceftriaxone can be avoided. Cross-reactivity with pharyngeal commensal Neisseria species reduces specificity and is a challenge for many assays. Progress with laboratory-based molecular tests to detect gonococcal resistance is being made but substantial challenges remain. No laboratory-based assay has been subjected to a field evaluation and no assay so far can be used as a point-of-care test. Given the threat of antimicrobial resistance, now is the time to exploit the molecular technologies used for diagnosis and to invest in the development of molecular gonococcal resistance tests that can be implemented for public health good.

Emerging Extended-Spectrum Cephalosporin Resistance in Neisseria gonorrhoeae

Over the last several decades, Neisseria gonorrhoeae has sequentially developed resistance to the agents recommended by the CDC and the Public Health Service for the treatment of gonorrhea. During the 1970s and through the 1990s, penicillin, tetracyclines, and the fluoroquinolones were recommended and subsequently removed as the therapy of choice for gonorrhea, leaving intramuscular ceftriaxone and the oral cephalosporin cefixime as the sole agents recommended for treatment of gonorrhea in 2010. In the late 1990s, treatment failures following oral cefixime therapy were recognized in Japan and the Far East, and subsequently, cefixime treatment failures were reported from the United Kingdom, Europe, and the United States. Gonococcal isolates from these cases showed diminished susceptibility to both cefixime and ceftriaxone, and molecular studies have shown that N. gonorrhoeae isolates with elevated cephalosporin MICs have genetic alterations primarily in the chromosomal penA gene, which encodes penicillin-binding protein 2. The altered proteins bind cephalosporins less efficiently, and isolates phenotypically demonstrate diminished cephalosporin susceptibility and elevated cefixime and ceftriaxone MICs. The penA alleles in these strains have a “mosaic” composition, as they contain nucleic acid sequences that were acquired from commensal Neisseria species. The strains also have genetic alterations in several other chromosomal loci that contribute to incremental cephalosporin resistance. With the utility of extended-spectrum cephalosporins for gonorrhea treatment being threatened, older agents (e.g., gentamicin and ertapenem) and newly developed antimicrobials (e.g., solithromycin) are now being evaluated as possible treatment options. The CDC has issued guidelines for the public health response to the emergence of cephalosporin-resistant N. gonorrhoeae. This plan includes improvements in gonococcal surveillance, identification by clinicians of “probable” and “suspected” treatment failures, the re-establishment of culture-based testing, and the timely performance of antimicrobial susceptibility testing on isolates obtained from treatment failures. Potential problems central to implementation of the response plan are also addressed.

A real-time PCR assay for direct characterization of the Neisseria gonorrhoeae GyrA 91 locus associated with ciprofloxacin susceptibility.

The objective of this study was to develop a real-time PCR method for specific detection of the gonococcal GyrA amino acid 91 locus directly in clinical samples so as to predict Neisseria gonorrhoeae ciprofloxacin susceptibility. The real-time PCR assay, GyrA91-PCR, was designed using two probes, one for detection of the WT S91 sequence and the other for detection of the S91F alteration. The performance of the assay was initially assessed using characterized N. gonorrhoeae isolates (n = 70), a panel of commensal Neisseria and Moraxella species (n = 55 isolates) and clinical samples providing negative results by a commercial N. gonorrhoeae nucleic acid amplification test (NAAT) method (n = 171). The GyrA91-PCR was then applied directly to N. gonorrhoeae NAAT-positive clinical samples (n = 210) from the year 2014 for which corresponding N. gonorrhoeae isolates with susceptibility results were also available. The GyrA91-PCR accurately characterized the GyrA 91 locus of all 70 N. gonorrhoeae isolates (sensitivity = 100%, 95% CI = 94.9%-100%), whereas all non-gonococcal isolates and N. gonorrhoeae NAAT-negative clinical samples gave negative results by the GyrA91-PCR (specificity = 100%, 95% CI = 98.4%-100%). When applied to the 210 N. gonorrhoeae NAAT-positive clinical samples, the GyrA91-PCR successfully characterized 195 samples (92.9%, 95% CI = 88.5%-95.9%). When compared with the corresponding bacterial culture results, positivity by the GyrA91-PCR WT probe correctly predicted N. gonorrhoeae susceptibility to ciprofloxacin in 161 of 162 (99.4%, 95% CI = 96.6%-99.9%) samples. The use of a PCR assay for detection of mutation in gyrA applied directly to clinical samples can predict ciprofloxacin susceptibility in N. gonorrhoeae.

005.3 Multiplex real-time pcr with high resolution melting analysis for detecting resistance mechanisms inneisseria gonorrhoeae

Background Molecular tests to detect antimicrobial resistance in Neisseria gonorrhoeae (NG) are urgently needed. Genetic methods are the mainstay of NG detection in many settings, but resistance testing still requires conventional phenotypic tests. The objective of this study was to develop an assay to detect the most clinically important genetic markers conferring resistance to antibiotics used for the treatment of gonorrhoea. Methods We designed a fluorescent dye real-time PCR assay combined with high resolution melting (HRM) analysis. Several triplex and duplex reactions included target sequences for: two NG-specific genes ( porA and opa ); targets specific for the penA mosaic XXXIV (A501, G545S), associated with reduced cephalosporin susceptibility; single nucleotide polymorphisms conferring resistance to ciprofloxacin (GyrA S91F), azithromycin (23S rRNA A2059G and C2611T) and spectinomycin (16S rRNA C1192T and 5S rRNA T24P). We tested >50 characterised NG isolates, including: clinical isolates resistant to ciprofloxacin, azithromycin, spectinomycin, ceftriaxone (strain F89), strains with reduced cephalosporin susceptibility, the wild-type reference strain ATCC49226, and commensal Neisseria spp. Results HRM analysis correctly identified: all NG strains and all mutations, except for the A501P mutation in strain F89. However, cross-reactions with commensal Neisseria spp. occurred for: penA mosaic XXXIV (n = 3 species) and 23S rRNA (n = 3 species). Conclusion Our multiplex PCR assay accurately identified NG and detected the most frequent mutations associated with antimicrobial resistance in cultured isolates. The assay provides results significantly quicker than current culture-based methods. The analytical sensitivity and specificity of the assay for use with urethral, rectal, pharyngeal and vaginal specimens should be evaluated in the near future.

001.4 Recent rise in reduced susceptibility to ceftriaxone inneisseria gonorrhoeaeis not caused by strains with apenamosaic gene

Background Resistance of Neisseria gonorrhoeae against third generation cephalosporins is a threat to public health. A known determinant is the presence of a mosaic penA gene in N.gonorrhoeae , partially derived from commensal Neisseria spp. We report resistance figures of N.gonorrhoeae against ceftriaxone from 2010 to 2013 and looked at penA characteristics of specific strains. Methods MICs for ceftriaxone were assesed from 2010–13 (4191 strains). A specific PCR identifying strains with a mosaic penA gene and partial sequence analysis (aa 180 – 550) of the penA gene were used for further characterisation of specific strains. Results Strains resistant to ceftriaxone were not found during the study period. The frequency of strains with an increased MIC (>0.032) to ceftriaxone was 5.2% in 2010, this rate dropped to 2.0 and 3.1% in 2011 and 2012 respectively, but increased to 7.8% in 2013. In 2010, 46/48 (96%) strains with an increased MIC against ceftriaxone contained a mosaic penA gene; in 2013, only 15/68 (22%) of such strains contained this gene. Sequence analysis of 16 of the strains isolated in 2013 with reduced susceptibility to ceftriaxone and lacking a mosaic penA gene showed that they all had an identical penA gene which was similar to type XVIII, including a 502 A-T mutation, but lacking the 543 G-S mutation. 1 Conclusion The recent increase of the frequency of strains with reduced susceptibility to ceftriaxone in 2013 is due to strains with a penA sequence not yet found in the Netherlands in 2010 among strains with reduced susceptibility to ceftriaxone. Disclosure of interest statement Nothing to declare Reference Whiley DM, Limnios EA, Ray S, et al . Diversity of penA alterations and subtypes in Neisseria gonorrhoeae strains from Sydney, Austrlia, that are less susceptible to ceftriaxone. Antimicrob Agents Chemother . 2007; 51 :3111–6

P07.10 Evaluation of the new bd max gc real time pcr assay, analytically and as a supplementary test to the bd probetec gc qx amplified dna assay, for molecular detection ofneisseria gonorrhoeae

Introduction The BD ProbeTec GC Qx Amplified DNA assay (Becton, Dickinson and Company) is used on the BD Viper System to detect Neisseria gonorrhoeae . However, suboptimal specificity and cross-reaction with commensal Neisseria species have been described. Recently, the BD Max GC real time (rt) PCR assay was developed for the BD Max System (BD) as a supplementary test. Methods We evaluated the performance of the new BD Max GC rt PCR assay by examining clinical specimens positive in the BD ProbeTec GC Qx Amplified DNA assay during July–October 2014 among 23815 screening or clinical patients (14846 females and 8969 males) as well as samples spiked with isolates of gonococci (n = 189), non-gonococcal Neisseria species (n = 261) and other closely related bacteria (n = 10). Results Of 23815 patients tested with the BD ProbeTec GC Qx Amplified DNA assay, 85 (0.6%) females and 259 (2.9%) males were positive. Of these 344 positive specimens, 322 were tested with BD Max GC rt PCR assay. Sixty-nine (21%) of these samples were negative in BD Max GC rt PCR assay, a gonococcal dual target PCR and in the APTIMA Combo 2 (Hologic). These 69 specimens were obtained from pharynx (50% of all screening positive pharyngeal specimens), urine (33%), vagina (11.4%), rectum (4.3%), and cervix (1.4%). In the analytical evaluation of the BD Max GC rt PCR assay, all gonococcal isolates were positive and all but one ( N. cinerea ) of the non-gonococcal isolates (99.4%) were negative. The N. cinerea isolate also cross-reacted in the BD ProbeTec GC Qx Amplified DNA assay. Conclusion The BD ProbeTec GC Qx Amplified DNA assay had a suboptimal specificity for both urogenital and extragenital clinical specimens. The new BD Max GC rt PCR assay showed a high clinical and analytical sensitivity and specificity, and might also be used for initial detection of N. gonorrhoeae . Disclosure of interest statement We are grateful to BD Diagnostics for providing the BD Max GC real time PCR tests. The present work was funded by grants from the Orebro County Council Research Committee and the Foundation for Medical Research at Orebro University Hospital, Sweden.

The Long and Winding Road (Apologies to the Beatles).

The Long and Winding Road (Apologies to the Beatles).

Non-pathogenic Neisseria: members of an abundant, multi-habitat, diverse genus

The genus Neisseria contains the important pathogens Neisseria meningitidis and Neisseria gonorrhoeae. These Gram-negative coccoid bacteria are generally thought to be restricted to humans and inhabit mucosal surfaces in the upper respiratory and genito-urinary tracts. While the meningococcus and gonococcus have been widely studied, far less attention has been paid to other Neisseria species. Here we review current knowledge of the distribution of commensal Neisseria in humans and other hosts. Analysis of the microbiome has revealed that Neisseria is an abundant member of the oropharyngeal flora, and we review its potential impact on health and disease. Neisseria also exhibit remarkable diversity, exhibiting both coccoid and rod-shaped morphologies, as well as environmental strains which are capable of degrading complex organic molecules.

O24 Confirming gc naat results: is it always necessary?: Abstract O24 Table 1

<h3>Introduction</h3> Current guidance recommends that all specimens testing positive using a <i>N. gonorrhoeae</i> Nucleic Acid Amplification Test (GC NAAT) be confirmed using a second test with an alternative target, in order to achieve a positive predictive value above 90%. <h3>Aim</h3> To determine rates of GC NAAT confirmations by primary screening test and specimen site. <h3>Methods</h3> 994 specimens which were GC NAAT positive at local laboratories were sent for confirmation using an in-house multiplex PCR with <i>Por</i>A and <i>opa </i>gene targets. A correlation between the confirmatory real-time PCR results, specimen site and GC screening NAAT was undertaken. For the purposes of this analysis equivocal results were regarded as positive and inhibited results were excluded. <h3>Results</h3> Overall, 57% of specimens examined could be confirmed as GC positive using the in-house real-time PCR test (Table 1). <h3>Discussion</h3> High rates of confirmation can be achieved when examining genital, rectal and urine specimens irrespective of the GC screening NAAT. However &gt;90% confirmatory rates were only achieved when examining male urine specimens which had been screened using the Probetec and Cobas Amplicor tests, although caution should be applied if extrapolating this data to low prevalence settings. Poor confirmation rates from throat specimens is probably due to cross-reactivity with commensal Neisseria, and highlights confirmation is essential when testing these samples.

Oral colonization with Neisseria highlights differences in wild derived mouse immune responses (MPF6P.650)

Abstract Neisseria species have the ability to colonize the host as either a commensal or pathogen depending on the strain and anatomical location. Human Neisseria species carriage estimates can reach as high as 50% of the population. Investigations of the immunological changes induced by Neisseria carriage, to date, have been inhibited by the lack of a small animal model. Here we set out to develop a mouse model of commensal Neisseria colonization. Three wild derived inbred mouse strains (PWK, WSB and CAST) along with C57BL/6 were tested. These mice were inoculated orally with a Neisseria strain isolated from wild caught mice in Tucson, Arizona. Mice were then sampled by oral swab weekly to determine Neisseria burdens in the oral cavity. Only the CAST/EiJ mice were completely susceptible to colonization (6/6) while C57BL/6 mice were weakly colonized (2/7). PWK and WSB mice were completely resistant to colonization. To determine if the immune response was responsible for the resistance of C57BL/6 mice both RAG-1-/- and MyD88-/- were inoculated. Interestingly, MyD88-/- mice were completely susceptible to colonization (5/5) while the RAG-1-/- mice were completely resistant (0/8), indicating the innate response in C57BL/6 mice was responsible for the resistance to colonization. Current work is aimed at dissecting the innate immune responses to different stimuli between C57BL/6 and CAST mice.

Nasal Inoculation of the Commensal Neisseria lactamica Inhibits Carriage of Neisseria meningitidis by Young Adults: A Controlled Human Infection Study.

Herd protection by meningococcal vaccines is conferred by population-level reduction of meningococcal nasopharyngeal colonization. Given the inverse epidemiological association between colonization by commensal Neisseria lactamica and meningococcal disease, we investigated whether controlled infection of human volunteers with N. lactamica prevents colonization by Neisseria meningitidis. In a block-randomized human challenge study, 310 university students were inoculated with 10(4) colony-forming units of N. lactamica or were sham-inoculated, and carriage was monitored for 26 weeks, after which all participants were reinoculated with N. lactamica and resampled 2 weeks later. At baseline, natural N. meningitidis carriage in the control group was 22.4% (36/161), which increased to 33.6% (48/143) by week 26. Two weeks after inoculation of N. lactamica, 33.6% (48/143) of the challenge group became colonized with N. lactamica. In this group, meningococcal carriage reduced from 24.2% (36/149) at inoculation to 14.7% (21/143) 2 weeks after inoculation (-9.5%; P = .006). The inhibition of meningococcal carriage was only observed in carriers of N. lactamica, was due both to displacement of existing meningococci and to inhibition of new acquisition, and persisted over at least 16 weeks. Crossover inoculation of controls with N. lactamica replicated the result. Genome sequencing showed that inhibition affected multiple meningococcal sequence types. The inhibition of meningococcal carriage by N. lactamica is even more potent than after glycoconjugate meningococcal vaccination. Neisseria lactamica or its components could be a novel bacterial medicine to suppress meningococcal outbreaks. This observation explains the epidemiological observation of natural immunity conferred by carriage of N. lactamica. NCT02249598.

Will targeting oropharyngeal gonorrhoea delay the further emergence of drug-resistant Neisseria gonorrhoeae strains?

Gonorrhoea is an important sexually transmitted infection associated with serious complications and enhanced HIV transmission. Oropharyngeal infections are often asymptomatic and will only be detected by screening. Gonococcal culture has low sensitivity (<50%) for detecting oropharyngeal gonorrhoea, and, although not yet approved commercially, nucleic acid amplification tests (NAAT) are the assay of choice. Screening for oropharyngeal gonorrhoea should be performed in high-risk populations, such as men-who-have-sex-with-men(MSM). NAATs have a poor positive predictive value when used in low-prevalence populations. Gonococci have repeatedly thwarted gonorrhoea control efforts since the first antimicrobial agents were introduced. The oropharyngeal niche provides an enabling environment for horizontal transfer of genetic material from commensal Neisseria and other bacterial species to Neisseria gonorrhoeae. This has been the mechanism responsible for the generation of mosaic penA genes, which are responsible for most of the observed cases of resistance to extended-spectrum cephalosporins (ESC). As antimicrobial-resistant gonorrhoea is now an urgent public health threat, requiring improved antibiotic stewardship, laboratory-guided recycling of older antibiotics may help reduce ESC use. Future trials of antimicrobial agents for gonorrhoea should be powered to test their efficacy at the oropharynx as this is the anatomical site where treatment failure is most likely to occur. It remains to be determined whether a combination of frequent screening of high-risk individuals and/or laboratory-directed fluoroquinolone therapy of oropharyngeal gonorrhoea will delay the further emergence of drug-resistant N. gonorrhoeae strains.

Principles and applications of typing methods for commensal Neisseria

This review describes the design as well as advantages and disadvantages for current phenotypic (antibiogram and serotyping) and molecular techniques (plasmid analysis, arbitrarily primed PCR, 16S rRNA, pulse-field gel electrophoresis and multilocus sequence typing) for typing of commensal Neisseria spp. compared with pathogenic Neisseria species. Identical methods for typing Neisseria species should not be used in all situations, that is, for microepidemiological, macroepidemiological or evolutionary questions.

Prevalence and Genotyping of Commensal Neisseria with Reduced Susceptibility to Penicillin

We analyzed 85 Neisseria spp. strains collected by swabbing from neutropenic patients to determine the prevalence of reduced susceptibility to penicillin and to ascertain the clonal relationship between these strains. High genetic diversity and an elevated level of penicillin resistance were found among commensal Neisseria clinical isolates.

Cytochrome c-based domain modularity governs genus-level diversification of electron transfer to dissimilatory nitrite reduction.

The genus Neisseria contains two pathogenic species (N. meningitidis and N. gonorrhoeae) in addition to a number of commensal species that primarily colonize mucosal surfaces in man. Within the genus, there is considerable diversity and apparent redundancy in the components involved in respiration. Here, we identify a unique c-type cytochrome (cN ) that is broadly distributed among commensal Neisseria, but absent in the pathogenic species. Specifically, cN supports nitrite reduction in N. gonorrhoeae strains lacking the cytochromes c5 and CcoP established to be critical to NirK nitrite reductase activity. The c-type cytochrome domain of cN shares high sequence identity with those localized c-terminally in c5 and CcoP and all three domains were shown to donate electrons directly to NirK. Thus, we identify three distinct but paralogous proteins that donate electrons to NirK. We also demonstrate functionality for a N. weaverii NirK variant with a C-terminal c-type heme extension. Taken together, modular domain distribution and gene rearrangement events related to these respiratory electron carriers within Neisseria are concordant with major transitions in the macroevolutionary history of the genus. This work emphasizes the importance of denitrification as a selectable trait that may influence speciation and adaptive diversification within this largely host-restricted bacterial genus.

Antibiotic resistance among commensal Neisseria species

Antibiotic resistance among commensal Neisseria species