Amoxicillin would still be advocated therefore as being a suitable first-line agent, while reduced susceptibility of Prevotella strains remains a matter of concern with penicillins. Amoxicillin/clavulanate, clindamycin, and metronidazole are useful alternatives in combating the anaerobic bacteria involved in dentoalveolar infection.

Objective. The aim of this study was to determine the incidence and bacteriology of bacteremia associated with various oral and maxillofacial surgical procedures. Methods.A total of 237 patients who underwent oral and maxillofacial surgery were included in this study. Blood samples were obtained for bacteriological examination immediately after the essential steps of the surgical procedure had been performed.Results. Bacteremia was detected in patients who underwent surgery for tumor, infection and trauma, and surgical reconstruction of jaw. In particular, decortication for osteomyelitis and tooth extraction resulted in a higher incidence of bacteremia compared with other surgical procedures. The incidence of bacteremia was not affected by oral hygiene, gingival inflammation, blood loss and duration of surgery. Furthermore, concerning tooth extraction, there was no statistical difference in the incidence of bacteremia with respect to the number of teeth extracted and the method of extraction.Extraction of teeth with odontogenic infection (periodontitis, periapical infection and pericoronitis) did however produce a significantly increased incidence of bacteremia compared with infection-free teeth (P<0.01).Viridans streptococci were the predominant group of bacteria isolated from the bacteremias. Conclusion.Oral and maxillofacial surgery involving trans-oral incision produces bacteremia, regardless of the extent and degree of surgical invasion. In particular, surgical procedure at infected sites is more likely to result in bacteremia compared with infection-free sites.

While most bacteria involved in dentoalveolar infection are highly susceptible to penicillin, some Prevotella strains exhibit resistance to this agent through the production of ␤-lactamase. The production of ␤-lactamase by Prevotella spp. is in turn associated with the expression of the genes cfxA and cfxA2. The aim of the present study was to determine the prevalence of cfxA and cfxA2 in Prevotella strains by use of real-time PCR and to assess the performance of this molecular method for the direct detection of the genes in 87 clinical samples (pus and root canal exudates) from dentoalveolar infection. Production of ␤-lactamase by each isolate was determined using a nitrocefin disk. ␤-Lactamase production was seen in 31% of Prevotella isolates, while all isolates of other species were ␤-lactamase negative. The penicillin resistance of isolates strongly correlated with the production of ␤-lactamase. Real-time PCR was found to detect the cfxA and cfxA2 genes from at least five cells per reaction mixture (5 ؋ 10 3 CFU/ml of pus). Using real-time PCR, the presence of cfxA and cfxA2 was evident for all 48 ␤-lactamase-positive Prevotella strains. In contrast, neither ␤-lactamase-negative Prevotella (n ‫؍‬ 91) or non-Prevotella (n ‫؍‬ 31) strains were positive for the genes. In this study, 31 of the 87 samples yielded ␤-lactamase-positive Prevotella results, and cfxA and cfxA2 were detected in all 31 samples. Of the 56 culture-negative samples, 8 (14%) were positive for cfxA and cfxA2 by the real-time PCR. This sensitive and specific molecular method offers a rapid clinical test for aiding in the selection of an appropriate antibiotic for treatment of dentoalveolar infection. Although penicillin remains largely effective in the treatment of dentoalveolar infection, ␤-lactamase-stable antibiotics should be considered in cases in which ␤-lactamase-positive Prevotella strains are involved.

Prevotella intermedia and Prevotella nigrescens are often regarded as principal causes of acute dentoalveolar infection; however, other species within the genus are also known to be associated with such infection. The aim of this study was to determine the in vitro proteolytic activity of these different Prevotella species that have been implicated with dentoalveolar infection. A total of 234 strains were obtained from pus specimens from dentoalveolar infection and from the plaque of healthy volunteers. Prevotella loescheii, Prevotella oralis, Prevotella melaninogenica, Prevotella buccae, and Prevotella denticola were all shown to have a proteolytic activity (8.5-10.5 x 10(-8) A-units) lower than that of P. intermedia and P. nigrescens (21.1-23.5 x 10(-8) A-units). In the case of P. loescheii, P. melaninogenica, and P. intermedia, the level of proteolytic activity for clinical strains was significantly (P < 0.05) higher than that recorded for commensal strains. Proteolytic activity for all species of Prevotella examined was inhibited by N-ethylmaleimide and phenymethylsulfonyl fluoride. This study suggests that Prevotella species associated with oral purulent infection produce cysteine and serine proteinases and that in certain species of Prevotella, the strains involved in infection exhibit higher proteolytic activity when compared with strains from healthy sites.

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