Aggregatibacter actinomycetemcomitans

Recent studies have shown a phylogenetic similarity of A. actinomycetemcomitans and Haemophilus aphrophilus, H. paraphrophilus, and H. segnis, suggesting the new genus Aggregatibacter for them.

It is one of the bacteria that might be implicated in destructive periodontal disease. Although it has been found more frequently in localized aggressive periodontitis,{{cite journal | vauthors = Slots J | title = The predominant cultivable organisms in juvenile periodontitis | journal = Scandinavian Journal of Dental Research | volume = 84 | issue = 1 | pages = 1–10 | date = January 1976 | pmid = 1061986 | doi = 10.1111/j.1600-0722.1976.tb00454.x }} prevalence in any population is rather high. It has also been isolated from actinomycotic lesions (mixed infection with certain Actinomyces species, in particular A. israelii). It possesses certain virulence factors that enable it to invade tissues, such as the pore-forming toxin leukotoxin A. It has also been isolated from women with bacterial vaginosis and as an etiologic agent in endocarditis.{{cite journal | vauthors = Africa CW, Nel J, Stemmet M | title = Anaerobes and bacterial vaginosis in pregnancy: virulence factors contributing to vaginal colonisation | journal = International Journal of Environmental Research and Public Health | volume = 11 | issue = 7 | pages = 6979–7000 | date = July 2014 | pmid = 25014248 | pmc = 4113856 | doi = 10.3390/ijerph110706979 | doi-access = free }} The pore-forming toxin LtxA of A. actinomycetemcomitans may be a trigger of the autoimmune disease rheumatoid arthritis due to its ability to stimulate protein citrullination, a post-translational protein modification targeted by autoantibodies in this disease.{{cite journal | vauthors = Konig MF, Abusleme L, Reinholdt J, Palmer RJ, Teles RP, Sampson K, Rosen A, Nigrovic PA, Sokolove J, Giles JT, Moutsopoulos NM, Andrade F | title = Aggregatibacter actinomycetemcomitans-induced hypercitrullination links periodontal infection to autoimmunity in rheumatoid arthritis | journal = Science Translational Medicine | volume = 8 | issue = 369 | pages = 369ra176 | date = December 2016 | pmid = 27974664 | pmc = 5384717 | doi = 10.1126/scitranslmed.aaj1921 }}{{cite journal | vauthors = Abbasi J | title = To Prevent Rheumatoid Arthritis, Look Past the Joints to the Gums | journal = JAMA | volume = 317 | issue = 12 | pages = 1201–1202 | date = March 2017 | pmid = 28273301 | doi = 10.1001/jama.2017.0764 }}

• Leukotoxin A: kills granulocytes, monocytes, and other white blood cells expressing integrin beta-2 (CD18)
• Cytolethal distending toxin
• Immunosuppression factors that inhibit blastogenesis, antibody production, and activate T-suppressor cells
• Inhibition of granulocyte functions
• Resistant to complement-mediated killing
• Lipopolysaccharides
• Surface antigens
• Heat shock proteins
• Antimicrobial resistance

• a strain, for example ATCC 29523, frequently in oral cavity, variable leukotoxin expression
• b strain Y4, most frequently in localized aggressive periodontitis, high leukotoxin expression; of the b subset, clone Jp2 is particularly leukotoxic{{cite journal | vauthors = Haubek D | title = The highly leukotoxic JP2 clone of Aggregatibacter actinomycetemcomitans: evolutionary aspects, epidemiology and etiological role in aggressive periodontitis | journal = APMIS. Supplementum | volume = 118 | issue = 130 | pages = 1–53 | date = September 2010 | pmid = 21214629 | doi = 10.1111/j.1600-0463.2010.02665.x | s2cid = 20882401 }}
• c strain ATCC 33384, low leukotoxin expression
• serotypes d, e, f, g
• within each serotype, leukotoxin expression can be highly variable between strains

In bacteria, small RNAs are involved in gene regulation. Jorth et al. identified 9 sRNA by Northern blotting from computer-predicted candidates in strain VT1169 and 202 sRNA by RNA seq in strain 624.{{cite journal | vauthors = Jorth P, Whiteley M | title = Characterization of a novel riboswitch-regulated lysine transporter in Aggregatibacter actinomycetemcomitans | journal = Journal of Bacteriology | volume = 192 | issue = 23 | pages = 6240–50 | date = December 2010 | pmid = 20889741 | pmc = 2981213 | doi = 10.1128/JB.00935-10 }}{{cite journal | vauthors = Jorth P, Trivedi U, Rumbaugh K, Whiteley M | title = Probing bacterial metabolism during infection using high-resolution transcriptomics | journal = Journal of Bacteriology | volume = 195 | issue = 22 | pages = 4991–8 | date = November 2013 | pmid = 23974023 | pmc = 3811578 | doi = 10.1128/JB.00875-13 }} A systematic screen by RNA-seq and RT-PCR in HK1651 strain (a clinical isolate from an aggressive periodontitis patient), quantified 70 sRNAs and further identified 17 differentially expressed sRNAs during growth phases.{{cite journal | vauthors = Oogai Y, Gotoh Y, Ogura Y, Kawada-Matsuo M, Hayashi T, Komatsuzawa H | title = Small RNA repertoires and their intraspecies variation in Aggregatibacter actinomycetemcomitans | journal = DNA Research | volume = 25 | issue = 2 | pages = 207–215 | date = December 2017 | pmid = 29211829 | pmc = 5909427 | doi = 10.1093/dnares/dsx050 }} Target prediction indicated possibility of sRNA interaction with several virulence genes. This study confirmed the presence of one of previously identified Fur regulated sRNAs JA04 identified in strain HK1651.{{citation needed|date=September 2020}}

• List of bacterial vaginosis microbiota
• Oral microbiology

{{Reflist|30em}}

• [http://bacdive.dsmz.de/index.php?search=11752&submit=Search Type strain of Aggregatibacter actinomycetemcomitans at BacDive – the Bacterial Diversity Metadatabase]

{{Periodontology}}

{{Gram-negative proteobacterial bacterial diseases}}

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Category:Pasteurellales

Category:Dentistry

Category:Capnophiles

Category:Bacterial vaginosis

Category:Bacteria described in 1912