Characterization of a new serotype g isolate of Aggregatibacter actinomycetemcomitans

Abstract

Aggregatibacter actinomycetemcomitans is usually isolated from the oral cavity where it is associated with active periodontitis. The species can be divided into six serotypes (a-f) according to their surface carbohydrate antigens. However, some clinical isolates cannot be grouped within these six serotypes. Gram-negative, facultative anaerobic, catalase-positive coccobacilli were isolated from a patient with periodontitis and identified by employing genetic, biochemical and serological analyses. Phenotypic data identified the isolate as A. actinomycetemcomitans. Serotype-specific polysaccharide antigen from the isolate was untypeable by immunodiffusion testing in comparison with reference A. actinomycetemcomitans serotype a to f strains. Biofilm formation by the isolate was strong but cytotoxic activity was low. Gas chromatography/mass spectroscopy analysis of partially methylated alditol acetates from surface polysaccharide showed the presence of 2,4-di-O-methyl-rhamnose and 2,3,6-tri-O-methyl-glucose, with a 1 : 1 m ratio. The (1)H- and (13)C-nuclear magnetic resonance spectra of the antigen showed that both constituent glycoses had alpha-anomeric configuration. It is proposed that the untyped strain is a new A. actinomycetemcomitans serotype, designated serotype g.

LL-37 Opsonizes and Inhibits Biofilm Formation of Aggregatibacter actinomycetemcomitans at Subbactericidal Concentrations

“…Some reported efficient phagocytosis and killing (37), while others found complement-mediated phagocytosis of A. actinomycetemcomitans to be generally inefficient and uptake of antibody-opsonized bacteria to result in the rapid cell death of neutrophils (38). Oral A. actinomycetemcomitans strains were divided into seven serotypes, a, b, c, d, e, f, and g (39,40). Increased resistance to phagocytic killing has been shown for serotype b strains.…”

Aggregatibacter actinomycetemcomitans: Patógeno importante en la periodontitis

“…23,25 Las pruebas serológicas se realizan para identificar los 7 serotipos (A -G). 26,28 Pruebas moleculares como PCR convencional y en tiempo real, son usados por ser muy sensibles y específicos para el diagnóstico de microorganismos. 29,30 A. actinomycetemcomitans y su relación con la PAL A. actinomycetemcomitans está presente en aproximadamente 95 % de las lesiones periodontales en pacientes con PAL, 8 aunque hay estudios que muestran porcentajes menores.…”

Virulence Mechanisms of Leukotoxin from Aggregatibacter actinomycetemcomitans

“…Molecular genetics has demonstrated a degree of biodiversity in the oral microflora and A. actinomycetemcomitans is genetically heterogeneous and comprises distinct clonal lineages that may have different virulence potentials (Kittichotirat et al, 2011). Seven serotypes have been identified among A. actinomycetemcomitans isolates; each serotype represents a distinct clonal lineage (Kaplan et al, 2002;Kilian et al, 2006;Takada et. al., 2010).…”