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Opsonization of Actinobacillus actinomycetemcomitans by LPS-Directed IgG Antibodies in Sera of Juvenile Periodontitis Patients
Published in Helmut Brade, Steven M. Opal, Stefanie N. Vogel, David C. Morrison, Endotoxin in Health and Disease, 2020
Microbiological studies of LJP patients have revealed that the subgingival microflora of these patients differ from that of periodontally healthy individuals and patients with adult periodontitis. Actinobacillus actinomycetemcomitans, a capnophilic gram-negative coccobacillus that is closely related to the oral haemophili (6–8), has been identified as a prominent member of the subgingival microflora of these patients. A. actinomycetemcomitans is present, albeit in relatively low numbers, in the subgingival microflora of approximately 20% of periodontally healthy juveniles and adults and a similar percentage of patients with adult periodontitis (7). In contrast, more than 95% of LJP subjects examined harbor this organism in high numbers. Further evidence for an association between A. actinomycetemcomitans and LJP derives from studies showing that elimination of this organism from subgingival plaque following antibiotic therapy correlates with resolution of periodontal lesions in these patients (9). Moreover, recurrence of disease activity is accompanied by the reappearance of A. actinomycetem-comitans in periodontal lesions of LJP patients. Several studies have provided evidence that A. actinomycetem-comitans may be transmitted among members of families with LJP (10,11).
Factors Controlling the Microflora of the Healthy Mouth
Published in Michael J. Hill, Philip D. Marsh, Human Microbial Ecology, 2020
Numerous examples are known of symbiosis through food chains where a metabolic product excreted by one oral species is utilized as nutrient or growth factor by another.9,159 Carlsson161 has summarized some of these interactions (Figure 27), and suggested that food webs is a more accurate term than food chains, as there are often several species producing a compound and several others consuming it. Thus, carbon dioxide is produced by Fusobacterium, Eubacterium, Bacteroides, and Peptostreptococcus species and is utilized by capnophilic (CO2-loving) organisms such as Capnocytophaga spp, E. corrodens, A. actinomycetemcomitans, and S. mutans. Campylobacter and Wolinella species require formate and hydrogen, which are produced by several species, among them also B. gingivalis and B. melaninogenicus. The latter two species require hemin, which can be supplied by W. recta,162 and menadione (vitamin K) provided by Veillonella species and others. Veillonella species do not ferment carbohydrates but degrade lactate produced by Streptococcus and Actinomyces species to acetate and hydrogen, which can then be used by other organisms.
Overwhelming Post-Splenectomy Infections in the Critical Care Unit
Published in Cheston B. Cunha, Burke A. Cunha, Infectious Diseases and Antimicrobial Stewardship in Critical Care Medicine, 2020
These two organisms, formerly classified as the Centers for Disease Control and Prevention (CDC) group dysgonic fermentor (DF)-2 and DF-2-like, are slender, capnophilic gram-negative bacilli. They are found in the oral cavities of dogs and cats. Classically, the infection is transmitted to man as a zoonosis from a dog bite, and in immunocompetent individuals, the infection tends to be mild. Severe infection rapidly progressing to shock and death can occur in the immunocompromised host, especially the asplenic host [24]. Classically, the illness in asplenics occurs 1–7 days after the bite with gram-negative bacilli, which can be seen on a peripheral blood smear or in a smear of the blood buffy coat in a patient with an eschar at the bite site [25]. Beta-lactamase activity can be found in about 30% of these strains, but sensitivity has been generally demonstrated by ampicillin/sulbactam and the third-generation cephalosporins such as ceftriaxone [26].
Site-specialization of human oral Gemella species
Published in Journal of Oral Microbiology, 2023
Julian Torres-Morales, Jessica L. Mark Welch, Floyd E. Dewhirst, Gary G. Borisy
Members of the genus Gemella are core species of the human oral microbiome [1] found in healthy subjects and are therefore regarded as commensals, although they are known to cause opportunistic infections. Compared to other members of the human microbiota, the genus has not attracted much attention: a search in PubMed for ‘Gemella’ yielded 634 publications (as of March 24, 2023), mostly about its presence in or isolation from clinical samples of patients with endocarditis, oral diseases, wound infections, vaginosis, or other conditions. The basic microbiology literature indicates that members of this genus are non-motile cocci, facultatively anaerobic, capnophilic, of low G+C content, catalase-negative, oxidase-negative, with a tendency to grow in pairs, tetrads, or short chains [2–4]. Gemella species are capable of fermenting glucose into lactate and acetate as major metabolic end products [5]. However, the roles that species of Gemella play in the human microbiome as a whole remain to be established.