Bacteriology of dentoalveolar abscesses in patients who have received empirical antibiotic therapy

We investigated aspirates of pus from dentoalveolar abscesses in 13 patients who had received empirical antibiotic therapy within 1 month before presentation at our facility. The antibiotics administered were lincomycin, amoxicillin, ampicillin, or a cephalosporin. Information on antibiotic therapy was obtained from the patients' medical histories. Cultures of all dentoalveolar abscesses yielded organisms. A total of 70 isolates (42 anaerobes and 28 facultative organisms) were recovered, representing 5.3 isolates (3.2 anaerobes and 2.1 facultative organisms) per specimen. The counts of bacteria ranged from 5 X 10(7) cfu/mL to 8 X 10(11) cfu/mL (mean count, 1.4 X 10(11) cfu/mL; median count, 2.3 X 10(10) cfu/mL). The predominant isolates were Prevotella species (25.7% of isolates), Peptostreptococcus species (17.1%), and Streptococcus species (14.2%). This study illustrates the polymicrobial nature of dentoalveolar abscesses as well as the predominant role played by anaerobic bacteria.