Neisseria

Last updated

Neisseria
Neisseria gonorrhoeae with pus cells.jpg
Neisseria gonorrhoeae by Gram-stain
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Bacteria
Phylum: Pseudomonadota
Class: Betaproteobacteria
Order: Neisseriales
Family: Neisseriaceae
Genus: Neisseria
Trevisan, 1885
Species

Neisseria is a large genus of bacteria that colonize the mucosal surfaces of many animals. Of the 11 species that colonize humans, only two are pathogens, N. meningitidis and N. gonorrhoeae .

Contents

Neisseria species are Gram-negative bacteria included among the Pseudomonadota, a large group of Gram-negative forms. Neisseria diplococci resemble coffee beans when viewed microscopically. [1]

Pathogenesis and classification

Pathogens

Species of this genus (family Neisseriaceae) of parasitic bacteria grow in pairs and occasionally fours, and thrive best at 98.6 °F (37 °C) in the animal body or serum media.

The genus includes:

The immune system's neutrophils are restricted in function due to the ability of Neisseria to evade opsonization by antibodies, and to replicate within neutrophils despite phagocytosis. Neisseria species are also able to alter their antigens to avoid being engulfed by a process called antigenic variation, which is observed primarily in surface-located molecules. The pathogenic species along with some commensal species, have type IV pili which serve multiple functions for this organism. Some functions of the type IV pili include: mediating attachment to various cells and tissues, twitching motility, natural competence, microcolony formation, extensive intrastrain phase, and antigenic variation.

Neisseria bacteria have also been shown to be an important factor in the early stages of canine plaque development. [2]

Phylogenetic tree of selected Neisseria species, based on concatenating the DNA sequences of all 896 core Neisseria genes, from Marri et al. 2010 Neisseria phylogenetic tree.png
Phylogenetic tree of selected Neisseria species, based on concatenating the DNA sequences of all 896 core Neisseria genes, from Marri et al. 2010

Nonpathogens

This genus also contains several, believed to be commensal, or nonpathogenic, species:

However, some of these can be associated with disease. [4] [5]

Biochemical identification

All the medically significant species of Neisseria are positive for both catalase and oxidase. Different Neisseria species can be identified by the sets of sugars from which they will produce acid. For example, N. gonorrhoeae makes acid from only glucose, but N. meningitidis produces acid from both glucose and maltose.

Polysaccharide capsule.N. meningitidis has a polysaccharide capsule that surrounds the outer membrane of the bacterium and protects against soluble immune effector mechanisms within the serum. It is considered to be an essential virulence factor for the bacteria. [6] N. gonorrhoeae possesses no such capsule.

Unlike most other Gram-negative bacteria, which possess lipopolysaccharide (LPS), both pathogenic and commensal species of Neisseria have a lipooligosaccharide (LOS) which consists of a core polysaccharide and lipid A. It functions as an endotoxin, protects against antimicrobial peptides, and adheres to the asialoglycoprotein receptor on urethral epithelium. LOS is highly stimulatory to the human immune system. LOS sialylation (by the enzyme Lst) prevents phagocytosis by neutrophils and complement deposition. LOS modification by phosphoethanolamine (by the enzyme LptA) provides resistance to antimicrobial peptides and complement. Strains of the same species have the ability to produce different LOS glycoforms. [7]

History

The genus Neisseria is named after the German bacteriologist Albert Neisser, who in 1879 discovered its first example, Neisseria gonorrhoeae, the pathogen which causes the human disease gonorrhea. Neisser also co-discovered the pathogen that causes leprosy, Mycobacterium leprae . These discoveries were made possible by the development of new staining techniques which he helped to develop.

Genomes

The genomes of at least 10 Neisseria species have been completely sequenced. [3] The best-studied species are N.meningitidis with more than 70 strains and N. gonorrhoeae with at least 10 strains completely sequenced. Other complete genomes are available for N. elongata, N. lactamica, [8] and N. weaveri. Whole genome shotgun sequences are available for hundreds of other species and strains. [9] N.meningitidis encodes 2,440 to 2,854 proteins while N. gonorrhoeae encodes from 2,603 to 2,871 proteins. N. weaveri (strain NCTC 13585) has the smallest known genome with only 2,060 encoded proteins [10] although N. meningitidis MC58 has been reported to have only 2049 genes. [3] The genomes are generally quite similar. For example, when the genome of N. gonorrhoeae (strain FA1090) is compared to that of N. meningitidis (strain H44/76) 68% of their genes are shared. [9]

Genome properties of Neisseria sp. [3]
speciesSize (bp)gene number
N. elongata2,260,1052589
N. sicca2,786,3092842
N. mucosa2,542,9522594
N. subflava2,288,2192303
N. flavescens2,199,4472240
N. cinerea1,876,3382050
N. polysaccharea2,043,5942268
N. lactamica 239702,148,2112359
N. gonorrhoeae FA10902,153,9222002
N. meningitidis MC582,184,4062049

Vaccine

Diseases caused by N. meningitidis and N. gonorrhoeae are significant health problems worldwide, the control of which is largely dependent on the availability and widespread use of comprehensive meningococcal vaccines. Development of neisserial vaccines has been challenging due to the nature of these organisms, in particular the heterogeneity, variability and/or poor immunogenicity of their outer surface components. As strictly human pathogens, they are highly adapted to the host environment, but have evolved several mechanisms to remain adaptable to changing microenvironments and avoid elimination by the host immune system. Currently, serogroup A, B, C, Y, and W-135 meningococcal infections can be prevented by vaccines. [11] However, the prospect of developing a gonococcal vaccine is remote. [12]

Antibiotic resistance

The acquisition of cephalosporin resistance in N. gonorrhoeae, particularly ceftriaxone resistance, has greatly complicated the treatment of gonorrhea, with the gonococcus now being classified as a "superbug". [13]

Genetic transformation

Genetic transformation is the process by which a recipient bacterial cell takes up DNA from a neighboring cell and integrates this DNA into the recipient’s genome by recombination. In N. meningitidis and N. gonorrhoeae, DNA transformation requires the presence of short DNA sequences (9-10 monomers residing in coding regions) of the donor DNA. These sequences are called DNA uptake sequences (DUSs). Specific recognition of DUSs is mediated by a type IV pilin. [14] Davidsen et al. [15] reported that in N. meningitidis and N. gonorrhoeae, DUSs occur at a significantly higher density in genes involved in DNA repair and recombination (as well as in restriction-modification and replication) than in other annotated gene groups. These authors proposed that the over-representation of DUS in DNA repair and recombination genes may reflect the benefit of maintaining the integrity of the DNA repair and recombination machinery by preferentially taking up genome maintenance genes that could replace their damaged counterparts in the recipient cell. Caugant and Maiden noted that the distribution of DUS is consistent with recombination being primarily a mechanism for genome repair that can occasionally result in generation of diversity, which even more occasionally, is adaptive. [16] It was also suggested by Michod et al. [17] that an important benefit of transformation in N. gonorrhoeae is recombinational repair of oxidative DNA damages caused by oxidative attack by the host’s phagocytic cells.

International Pathogenic Neisseria Conference

The International Pathogenic Neisseria Conference (IPNC), occurring every two years, is a forum for the presentation of cutting-edge research on all aspects of the genus Neisseria. This includes immunology, vaccinology, and physiology and metabolism of N. meningitidis, N. gonorrhoeae and the commensal species. The first IPNC took place in 1978, and the most recent one was in September 2016. Normally, the location of the conference switches between North America and Europe, but it took place in Australia for the first time in 2006, where the venue was located in Cairns. [18]

Related Research Articles

<span class="mw-page-title-main">Pilus</span> A proteinaceous hair-like appendage on the surface of bacteria

A pilus is a hair-like appendage found on the surface of many bacteria and archaea. The terms pilus and fimbria can be used interchangeably, although some researchers reserve the term pilus for the appendage required for bacterial conjugation. All conjugative pili are primarily composed of pilin – fibrous proteins, which are oligomeric.

<i>Neisseria gonorrhoeae</i> Species of bacterium

Neisseria gonorrhoeae, also known as gonococcus (singular) or gonococci (plural), is a species of Gram-negative diplococci bacteria isolated by Albert Neisser in 1879. It causes the sexually transmitted genitourinary infection gonorrhea as well as other forms of gonococcal disease including disseminated gonococcemia, septic arthritis, and gonococcal ophthalmia neonatorum.

The restriction modification system is found in bacteria and other prokaryotic organisms, and provides a defense against foreign DNA, such as that borne by bacteriophages.

<span class="mw-page-title-main">Lipopolysaccharide</span> Class of molecules found in the outer membrane of Gram-negative bacteria

Lipopolysaccharides (LPS) are large molecules consisting of a lipid and a polysaccharide that are bacterial toxins. They are composed of an O-antigen, an outer core, and an inner core all joined by covalent bonds, and are found in the bacterial capsule, the outermost membrane of cell envelope of Gram-negative bacteria, such as E. coli and Salmonella. Today, the term endotoxin is often used synonymously with LPS, although there are a few endotoxins that are not related to LPS, such as the so-called delta endotoxin proteins produced by Bacillus thuringiensis.

MeNZB was a vaccine against a specific strain of group B meningococcus, used to control an epidemic of meningococcal disease in New Zealand. Most people are able to carry the meningococcus bacteria safely with no ill effects. However, meningococcal disease can cause meningitis and sepsis, resulting in brain damage, failure of various organs, severe skin and soft-tissue damage, and death.

<span class="mw-page-title-main">Bacterial capsule</span> Polysaccharide layer that lies outside the cell envelope in many bacteria

The bacterial capsule is a large structure common to many bacteria. It is a polysaccharide layer that lies outside the cell envelope, and is thus deemed part of the outer envelope of a bacterial cell. It is a well-organized layer, not easily washed off, and it can be the cause of various diseases.

<span class="mw-page-title-main">Neisseriaceae</span> Family of bacteria

The Neisseriaceae are a family of Pseudomonadota, within the Neisseriales order of Betaproteobacteria. While many organisms in the family are mammalian commensals or part of the normal flora, the genus Neisseria includes two important human pathogens, specifically those responsible for gonorrhea and many cases of meningitis. As a group, the Neisseriaceae are strictly aerobic and Gram-negative, occur mainly in pairs (diplococci), and typically do not have flagella.

Multilocus sequence typing (MLST) is a technique in molecular biology for the typing of multiple loci, using DNA sequences of internal fragments of multiple housekeeping genes to characterize isolates of microbial species.

<i>Neisseria meningitidis</i> Species of bacterium that can cause meningitis

Neisseria meningitidis, often referred to as the meningococcus, is a Gram-negative bacterium that can cause meningitis and other forms of meningococcal disease such as meningococcemia, a life-threatening sepsis. The bacterium is referred to as a coccus because it is round, and more specifically a diplococcus because of its tendency to form pairs.

<span class="mw-page-title-main">Meningococcal disease</span> Often life-threatening bacterial infection

Meningococcal disease describes infections caused by the bacterium Neisseria meningitidis. It has a high mortality rate if untreated but is vaccine-preventable. While best known as a cause of meningitis, it can also result in sepsis, which is an even more damaging and dangerous condition. Meningitis and meningococcemia are major causes of illness, death, and disability in both developed and under-developed countries.

Pilin refers to a class of fibrous proteins that are found in pilus structures in bacteria. These structures can be used for the exchange of genetic material, or as a cell adhesion mechanism. Although not all bacteria have pili or fimbriae, bacterial pathogens often use their fimbriae to attach to host cells. In Gram-negative bacteria, where pili are more common, individual pilin molecules are linked by noncovalent protein-protein interactions, while Gram-positive bacteria often have polymerized LPXTG pilin.

Uptake signal sequences (USS) are short DNA sequences preferentially taken up by competent bacteria of the family Pasteurellaceae. Similar sequences, called DNA uptake sequences (DUS), are found in species of the family Neisseriaceae.

Neisseria lactamica is a gram-negative diplococcus bacterium. It is strictly a commensal species of the nasopharynx. Uniquely among the Neisseria they are able to produce β-D-galactosidase and ferment lactose.

<span class="mw-page-title-main">Gonorrhea</span> Sexually transmitted infection

Gonorrhoea or gonorrhea, colloquially known as the clap, is a sexually transmitted infection (STI) caused by the bacterium Neisseria gonorrhoeae. Infection may involve the genitals, mouth, or rectum. Infected men may experience pain or burning with urination, discharge from the penis, or testicular pain. Infected women may experience burning with urination, vaginal discharge, vaginal bleeding between periods, or pelvic pain. Complications in women include pelvic inflammatory disease and in men include inflammation of the epididymis. Many of those infected, however, have no symptoms. If untreated, gonorrhea can spread to joints or heart valves.

NmVac4-A/C/Y/W-135 is the commercial name of the polysaccharide vaccine against the bacterium that causes meningococcal meningitis. The product, by JN-International Medical Corporation, is designed and formulated to be used in developing countries for protecting populations during meningitis disease epidemics.

<span class="mw-page-title-main">Antibiotic resistance in gonorrhea</span>

Neisseria gonorrhoeae, the bacterium that causes the sexually transmitted infection gonorrhea, has developed antibiotic resistance to many antibiotics. The bacteria was first identified in 1879.

Neisseria bacilliformis is a bacterium commonly found living as a commensal in the mucous membranes of mammals. However, depending on host immunocompetence, there have been documented cases of N. bacilliformis infections of the respiratory tract and oral cavity thus making it an opportunistic pathogen. It was originally isolated from patients being treated in a cancer center. Rarely, a more serious infection such as endocarditis can occur often as a result of a predisposing condition.

<i>Neisseria flavescens</i> Species of bacterium

Neisseria flavescens was first isolated from cerebrospinal fluid in the midst of an epidemic meningitis outbreak in Chicago. These gram-negative, aerobic bacteria reside in the mucosal membranes of the upper respiratory tract, functioning as commensals. However, this species can also play a pathogenic role in immunocompromised and diabetic individuals. In rare cases, it has been linked to meningitis, pneumonia, empyema, endocarditis, and sepsis.

<span class="mw-page-title-main">Phasevarion</span>

In bacteria, phasevarions mediate a coordinated change in the expression of multiple genes or proteins. This occurs via phase variation of a single DNA methyltransferase. Phase variation of methyltransferase expression results in differential methylation throughout the bacterial genome, leading to variable expression of multiple genes through epigenetic mechanisms.

<span class="mw-page-title-main">Neisseria RNA thermometer</span>

RNA thermometers (RNATs) regulate gene expression in response to temperature, allowing pathogens such as Neisseria meningitidis to switch on silent genes after entering the host organism. However the temperature for expression of Neisseria virulence-associated traits is 42 °C while other bacterial pathogen RNATs require 37 °C. This is probably because N. meningitidis is an obligate commensal of the human nasopharynx and becomes pathogenic during inflammation due to viral infection. Three independent RNA thermosensors were identified in the 5′UTRs of genes needed for: capsule biosynthesis (cssA), the expression of factor H binding protein (fHbp) and sialylation of lipopolysaccharide, which is essential for bacterial resistance against immune killing (lst). The very different nucleotide sequence and predicted inhibitory structures of the three RNATs indicate that they have evolved independently.

References

  1. Ryan KJ; Ray CG, eds. (2004). Sherris Medical Microbiology (4th ed.). McGraw Hill. ISBN   978-0-8385-8529-0.
  2. Early Canine Plaque Biofilms: Characterization of Key Bacterial Interactions Involved in Initial Colonization of Enamel. Lucy J. Holcombe, Niran Patel, Alison Colyer, Oliver Deusch, Ciaran O’Flynn, Stephen Harris. PLOS One, 2014.
  3. 1 2 3 4 Marri, Pradeep Reddy; Paniscus, Mary; Weyand, Nathan J.; Rendón, María A.; Calton, Christine M.; Hernández, Diana R.; Higashi, Dustin L.; Sodergren, Erica; Weinstock, George M. (2010-07-28). "Genome Sequencing Reveals Widespread Virulence Gene Exchange among Human Neisseria Species". PLOS ONE. 5 (7): e11835. Bibcode:2010PLoSO...511835M. doi: 10.1371/journal.pone.0011835 . ISSN   1932-6203. PMC   2911385 . PMID   20676376.
  4. Tronel H, Chaudemanche H, Pechier N, Doutrelant L, Hoen B (May 2001). "Endocarditis due to Neisseria mucosa after tongue piercing". Clin. Microbiol. Infect. 7 (5): 275–6. doi: 10.1046/j.1469-0691.2001.00241.x . PMID   11422256.
  5. Wolfgang, WJ; Passaretti, TV; Jose, R; Cole, J; Coorevits, A; Carpenter, AN; Jose, S; Van Landschoot, A; Izard, J; Kohlerschmidt, DJ; Vandamme, P; Dewhirst, FE; Fisher, MA; Musser, KA (April 2013). "Neisseria oralis sp. nov., isolated from healthy gingival plaque and clinical samples". International Journal of Systematic and Evolutionary Microbiology. 63 (Pt 4): 1323–8. doi:10.1099/ijs.0.041731-0. PMC   3709538 . PMID   22798652.
  6. Ullrich, M, ed. (2009). Bacterial Polysaccharides: Current Innovations and Future Trends. Caister Academic Press. ISBN   978-1-904455-45-5.
  7. Wilson, Brenda A.; Winkler, Malcolm E.; Ho, Brian Thomas (2019). Bacterial pathogenesis: a molecular approach (4th ed.). Washington, DC: ASM Press. p. 161. ISBN   978-1-55581-940-8.
  8. Minogue, T. D.; Daligault, H. A.; Davenport, K. W.; Bishop-Lilly, K. A.; Bruce, D. C.; Chain, P. S.; Chertkov, O.; Coyne, S. R.; Freitas, T. (2014-09-25). "Draft Genome Assembly of Neisseria lactamica Type Strain A7515". Genome Announcements. 2 (5): e00951–14. doi:10.1128/genomeA.00951-14. PMC   4175205 . PMID   25291770.
  9. 1 2 "Neisseria in the PATRIC database". PATRIC. 2017-02-26. Retrieved 2017-02-26.
  10. Alexander, Sarah; Fazal, Mohammed-Abbas; Burnett, Edward; Deheer-Graham, Ana; Oliver, Karen; Holroyd, Nancy; Parkhill, Julian; Russell, Julie E. (2016-08-25). "Complete Genome Sequence of Neisseria weaveri Strain NCTC13585". Genome Announcements. 4 (4): e00815–16. doi:10.1128/genomeA.00815-16. PMC   5000823 . PMID   27563039.
  11. "meningococcal group B vaccine". Medscape. WebMD. Retrieved December 16, 2015.
  12. Seib KL, Rappuoli R (2010). "Difficulty in Developing a Neisserial Vaccine". Neisseria: Molecular Mechanisms of Pathogenesis. Caister Academic Press. ISBN   978-1-904455-51-6.
  13. Unemo M, Nicholas RA (December 2012). "Emergence of multidrug-resistant, extensively drug-resistant and untreatable gonorrhea". Future Microbiol. 7 (12): 1401–1422. doi:10.2217/fmb.12.117. PMC   3629839 . PMID   23231489.
  14. Cehovin A, Simpson PJ, McDowell MA, Brown DR, Noschese R, Pallett M, Brady J, Baldwin GS, Lea SM, Matthews SJ, Pelicic V (2013). "Specific DNA recognition mediated by a type IV pilin". Proc. Natl. Acad. Sci. U.S.A. 110 (8): 3065–70. Bibcode:2013PNAS..110.3065C. doi: 10.1073/pnas.1218832110 . PMC   3581936 . PMID   23386723.
  15. Davidsen T, Rødland EA, Lagesen K, Seeberg E, Rognes T, Tønjum T (2004). "Biased distribution of DNA uptake sequences towards genome maintenance genes". Nucleic Acids Res. 32 (3): 1050–8. doi:10.1093/nar/gkh255. PMC   373393 . PMID   14960717.
  16. Caugant DA, Maiden MC (2009). "Meningococcal carriage and disease--population biology and evolution". Vaccine. 27 (Suppl 2): B64–70. doi:10.1016/j.vaccine.2009.04.061. PMC   2719693 . PMID   19464092.
  17. Michod RE, Bernstein H, Nedelcu AM (2008). "Adaptive value of sex in microbial pathogens". Infect. Genet. Evol. 8 (3): 267–85. doi:10.1016/j.meegid.2008.01.002. PMID   18295550.
  18. "IPNC - Neisseria.org". neisseria.org. Retrieved 2021-01-02.