RESUMO
AIM: To determine the presence of Prevotella species, the cfxA/cfxA2, blaZ and blaTEM genes associated with resistance to lactamic agents in different oral niches of children with pulp necrosis. METHODOLOGY: Children with pulp necrosis in primary teeth had samples of saliva, supragingival, pulp chamber and root canal biofilms collected and tested for Prevotella species (P. intermedia, P. nigrescens, P. tannerae) and for beta-lactam resistance genes (cfxA/cfxA2, blaZ and blaTEM). The presence of bacterial DNA was examined through PCR, with a specific primer directed to the 16S rRNA gene. Specific primers were used to detect the Prevotella species and beta-lactam resistance genes. The chi-square test was used to analyse associations between the presence of bacteria and clinical variables. The Cochran's Q test was used to assess whether the proportion of gene detection is the same between different sites. RESULTS: Thirty-two teeth were sampled from 27 patients with a mean age of 5.5 years (±1.76). The total detection rate of Prevotella strains was 29.1%, 25%, 21.8% and 32.29% in saliva, supragingival, pulp chamber and root canal samples, respectively. P. nigrescens was the most commonly detected species in all oral niches. The previous use of antibiotics was associated with detection of P. nigrescens in saliva (P = 0.03). Pain was associated with the presence of P. nigrescens (P = 0.04) and P. tannerae (P = 0.01) in pulp chamber biofilm. blaTEM was detected in the four oral niches, being more frequent (23.8%) in supragingival biofilm (Cochran's Q test, P = 0.04). The presence of P. intermedia in SB and PC was associated with the detection of blaTEM in saliva (P = 0.04). The cfxA/cfxA2 and blaZ genes were not detected in any of the four oral niches. CONCLUSIONS: The oral cavity of children with pulp necrosis had a variable distribution of Prevotella strains in different niches. Saliva, supragingival biofilm, pulp chamber and root canals of primary teeth with necrotic pulps can harbour resistance genes to beta-lactams agents.
