Beta-lactamase production in Prevotella intermedia, Prevotella nigrescens, and Prevotella pallens genotypes and in vitro susceptibilities to selected antimicrobial agents

The present study investigated the beta-lactamase production of 73 Prevotella intermedia, 84 Prevotella nigrescens, and 14 Prevotella pallens isolates and their in vitro susceptibilities to six antimicrobial agents. The P. intermedia and P. nigrescens isolates were recovered from oral and extraoral samples obtained from subjects in two geographic locations from 1985 to 1995. The clonality of the beta-lactamase-positive and beta-lactamase-negative isolates and the clustering of the genotypes were studied by arbitrarily primed-PCR fingerprinting. beta-Lactamase production was detected in 29% of P. intermedia isolates, 29% of P. nigrescens isolates, and 57% of P. pallens isolates. No difference in the frequencies of beta-lactamase production by P. intermedia and P. nigrescens between isolates from oral and extraoral sites, between isolates obtained at different time periods, or between P. intermedia isolates from different geographic locations was observed. However, the P. nigrescens isolates from the United States were significantly more frequently (P = 0.015) beta-lactamase positive than those from Finland. No association between the genotypes and beta-lactamase production or between the genotypes and the sources of the isolates was found. The penicillin G MICs at which 90% of the isolates were inhibited were 8 microg/ml for P. intermedia, 8 microg/ml for P. nigrescens, and 16 microg/ml for P. pallens. For the beta-lactamase-negative isolates, the corresponding values were 0.031, 0.031, and 0.125 microg/ml, and for the beta-lactamase-positive isolates, the corresponding values were 16, 8, and 32 microg/ml. All isolates were susceptible to amoxicillin-clavulanate, cefoxitin, metronidazole, azithromycin, and trovafloxacin. The MICs of amoxicillin-clavulanate and cefoxitin were relatively higher for the beta-lactamase-positive population than for the beta-lactamase-negative population.

Periodontal findings in spouses. A clinical, radiographic and microbiological study

Clinical, radiographic and microbiological examination of periodontal conditions was carried out in 2 groups of married couples to assess similarities between husband and wife. The diseased probands (n = 10) exhibited advanced periodontitis and the healthy ones (n = 10) were periodontally normal. The clinical examination comprised the assessment of plaque, probing pocket depths, gingival bleeding on probing, suppuration, supragingival and subgingival calculus. The extent and type of alveolar bone loss was determined from panoramic radiographs. Bacterial samples were taken from the 6 deepest and most inflamed periodontal pockets and from stimulated saliva. The samples were cultured for Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Campylobacter rectus and Peptostreptococcus micros. The mean detection frequency of moderately deep pockets (4-5 mm) and deep pockets (> or = 6 mm) was significantly higher in the diseased probands than in their spouses. The mean detection frequency of moderately deep pockets was significantly higher in the spouses of the diseased probands than in the spouses of the healthy ones. Deep pockets were found in 6 spouses of the diseased probands, whereas only in 2 spouses of the healthy ones. Both diseased proband and his/her spouse harbored A. actinomycetemcomitans, P. gingivalis, P. intermedia, C. rectus and P. micros in 4, 6, 9, 9 and 4 couples, respectively. Both healthy proband and his/her spouse harbored the pathogens in 0, 1, 9, 5 and 3 couples, respectively. P. gingivalis was found in 7 spouses of the diseased probands, but only in 2 spouses of the healthy ones.(ABSTRACT TRUNCATED AT 250 WORDS)