Distribution of serotype-specific genotypes of aggregatibacter actinomycetemcomitans in Brazilian patients with down syndrome with different periodontal conditions / Distribución de los serotipos genotipos específicos de aggregatibacter actinomycetemcomitans en los pacientes brasileños con síndrome de down con diferentes condiciones periodontales

This study evaluated the occurrence of highly or minimally leukotoxic strains of Aggregatibacter actinomycetemcomitans (Aa) from patients with Down syndrome and the distribution of the different serotype-specific genotypes of this microorganism. Sixty-seven patients with Down syndrome were subjected to dental, periodontal and radiographic evaluations. Samples of subgingival biofilm were collected and plated onto TSBV agar and characteristic colonies of A. actinomycetemcomitans were identified by biochemical methods. The occurrence of this bacterium was also evaluated directly in the clinical specimens by PCR. The presence of 530 bp deletion in the promoter region was also determined by PCR in order to evaluate distribution of highly or minimally leukotoxic strains. A. actinomycetemcomitans was detected in 11.1 percent by culture and 22.2 percent by PCR from periodontally healthy subjects, 100 percent of the patients with Down syndrome with aggressive periodontitis, 50 percent and 75 percent of patients with chronic periodontitis by culture and PCR respectively. Only two patients with aggressive periodontitis were colonized by highly leukotoxic Aa. Serotype-specific genotypes a and c were the most prevalent. The results suggest the role of peculiar characteristics of Aa and patients with Down syndrome in the development of periodontitis and the influence of peculiar characteristics of the population in this process.

Este estudio evaluó la presencia de cepas altamente o mínimamente toxicas de Aggregatibacter actinomycetemcomitans (Aa) de los pacientes con síndrome de Down y la distribución de los serotipos genotipos específicos de este microrganismo por cultivo y PCR. Sesenta y siete pacientes con síndrome de Down fueron sometidos a un tratamiento dental y evaluaciones clínicas. Las muestras de biofilme subgingival fueron recogidas y cultivadas en agar TSBV y colonias características de Aa fueran identificadas mediante métodos bioquímicos. La presencia de esta bacteria se evaluó también directamente en las muestras clínicas por PCR. Los aislados y las muestras clínicas también se probaron con el fin de evaluar la distribución de serotipos de genotipos específicos por PCR, mientras que la presencia de delección de 530 bp en la región promotora del gen ltxC también fue determinado por PCR con el fin de evaluar de distribución de las cepas altamente o mínimamente toxicas. Aa fue aislado en 11,1 por ciento y 22,2 por ciento por PCR de pacientes periodontalmente sanos; en todos los pacientes con síndrome de Down con periodontitis agresiva, y en 50 por ciento y 75 por ciento de los pacientes con periodontitis crónica por cultivo y PCR, respectivamente. Sólo dos pacientes con periodontitis agresiva fueron colonizados por cepas altamente tóxicas. Los serotipos y genotipos específicos a y c fueron los más frecuentes. Los resultados sugieren una asociación de las peculiares características de Aa con las características de los pacientes con síndrome de Down en el desarrollo de la periodontitis.

Virulencia y variabilidad de Porphyromonas gingivalis y Aggregatibacter actinomycetemcomitans y su asociación a la periodontitis / Virulence and variability on Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans and their association to periodontitis

Las periodontitis son un conjunto de patologías de naturaleza inflamatoria y etiología infecciosa producidas por el biofilm patogénico subgingival. Porphyromonas gingivalis y Aggregatibacter actinomycetemcomitans son bacterias periodonto-patógenas que pueden causar daño directo a las estructuras periodontales a través de los diversos factores de virulencia que expresan. Sobre la base de estos factores de virulencia, distintos genotipos y serotipos bacterianos se han descrito, cada uno de ellos con una potencial variable patogenicidad. En esta revisión bibliográfica se describen diferentes factores de virulencia de P. gingivalis y A. actinomycetemcomitans y se discute la variable inmunogenicidad y patogenicidad de los distintos genotipos y serotipos descritos para ellos. Tanto P. gingivalis como A. actinomycetemcomitans poseen diversos factores de virulencia asociados al inicio, progresión y severidad de las periodontitis. En P. gingivalis, los factores de virulencia para los cuales se describen distintos genotipos y/o serotipos son fimbria, LPS y cápsula bacteriana, y en A. actinomycetemcomitans son leucotoxina A, Cdt y LPS. Cada uno de estos distintos genotipos y serotipos induce una respuesta inmuno-inflamatoria diferente en el hospedero y, por lo tanto, se podrían asociar a una variable patogenicidad y podrían determinar las características clínicas de la enfermedad.

Periodontitis represents a heterogenic group of periodontal infections elicited by bacteria residing at the subgingival biofilm. Although this biofilm is constituted by a broad variety of bacterial species, only a limited number has been associated with the periodontitis aetiology, among them Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans. Both P. gingivalis and A. actinomycetemcomitans express a number of virulence factors that contribute to direct tissue damage and, based on them, distinct genotypes and serotypes have been described, each one with a potential variable pathogenicity. This review aimed to analyze the different virulence factors described for P. gingivalis and A. actinomycetemcomitans and to discuss the variable immunogenicity and pathogenicity of their serotypes and genotypes. P. gingivalis and A. actinomycetemcomitans express different virulence factors and they determine the initiation, progression, and severity of periodontitis. In P. gingivalis, distinct serotypes and/or genotypes are described based on fimbriae, LPS, and capsule. Additionally, in A. actinomycetemcomitans distinct serotypes and/or genotypes are described based on leucotoxin A, Cdt, and LPS. These distinct serotypes and genotypes induce a differential immunoinflammatory response and, thus, could be associated with variations in pathogenicity and reflected in clinic characteristics of the disease.

Occurrence of Aggregatibacter actinomycetemcomitans in Brazilian indians from Umutina Reservation, Mato Grosso, Brazil

Aggregatibacter actinomycetemcomitans is associated with periodontal disease, especially localized aggressive periodontitis, produces a potent leukotoxin and its distribution is influenced by ethnic characteristics of the population. Objective: Using culture and polymerase chain reaction (PCR) techniques, this study evaluated the occurrence of this microorganism and the distribution of leukotoxic strains isolated from Indians belonging to the Umutima Reservation, Mato Grosso, Brazil. MATERIAL AND METHODS: Forty-eight native Brazilians with gingivitis and 38 with chronic periodontitis, belonging to Umutina, Paresi, Bororo, Bakairi, Kayabi, Irantxe, Nambikwara and Terena ethnicities, were studied. Subgingival, supragingival and saliva samples of each patient were collected and transferred to VMGA III medium and to ultra pure Milli Q water. Bacteria were grown on TSBV agar and incubated in anaerobiosis (90 percent N2 + 10 percent CO2) at 37ºC for 72 h. The presence of the ltx promoter was determined by PCR, and a 530 bp deletion in the promoter was evaluated by using specific primers. RESULTS: A. actinomycetemcomitans was isolated from 8.33 percent of saliva, supragingival and subgingival samples from patients with gingivitis and from 18.42 percent of saliva and supragingival biofilm, and 26.32 percent subgingival biofilm from patients with chronic periodontitis. By PCR, the bacterial DNA was detected in 8.33 percent of saliva, supragingival and subgingival biofilms from patients with gingivitis and from 23.68 percent of saliva, 28.95 percent supragingival biofilm and 34.21 percent subgingival biofilm from patients with periodontitis. All strains were grouped as non-JP2 clones based on the absence of deletion in the leukotoxin promoter. Differences among the microbial and clinical parameters in patients were analyzed by using the Mann-Whitney, Chi-square or Fisher's exact tests. CONCLUSIONS: The present results suggest that A. actinomycetemcomitans ...

Nucleic acid probes in periodontal diagnosis.

Periodontal Disease is considered as an infection caused by a variety of microorganisms. Considering the vast range of microbial species involved in the causation of periodontal diseases, a specific diagnostic procedure, to identify the various organisms involved is a major necessity. A number of diagnostic procedures, including microbiological and immunological have been utilized in the diagnosis of periodontal disease. The DNA probe technology provides both a sensitive and specific assay and also alleviates concern for transport of the fastidious microorganisms in clinical samples, fulfills the need for a specific and rapid test, that does not require the preservation of viable microorganisms. DNA probes are now being used to identify the various putative pathogen's including; A. actinomycetemcomitans, P. gingivalis, P. intermedia, B. forsythus, etc. Besides DNA probes have also been proven an advantage over the various other available procedures in periodontal diagnosis.