ISSN:
1600-051X
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Medicine
Notes:
Aim: The purpose of the present investigation was to determine the percentage and identity of antibiotic-resistant species in subgingival plaque and saliva samples from chronic periodontitis patients treated by scaling and root planing followed by orally administered amoxicillin or metronidazole.Method: In all, 20 chronic periodontitis patients were selected for study. After clinical and microbiological monitoring, subjects were randomly assigned to receive either orally administered amoxicillin at the dosage of 500 mg, 3 times daily for 14 days or orally administered metronidazole at the dosage of 250 mg, 3 times daily for 14 days. For the antibiotic resistance determinations, subgingival plaque samples were taken from six posterior teeth at baseline, and 90 days; and from two randomly selected teeth at 3, 7 and 14 days during and after antibiotic administration. Samples were plated on enriched blood agar plates with or without either 2 µg/mL metronidazole or 2 µg/mL amoxicillin. Colonies were counted at 7 days. Significant differences in percentage of resistant organisms over time were determined by the Quade test. Microbial growth was washed from antibiotic-containing media and the identity of species determined using checkerboard DNA–DNA hybridization. Data were compared with those obtained in a previous study from subjects receiving SRP only or SRP followed by 14 days of orally administered doxycycline. The level of doxycycline used to determine antibiotic resistance in that study was 4 µg/mL.Results: The mean percentage of resistant isolates increased during antibiotic administration and returned to baseline levels by 90 days post therapy. The mean percentages (± SEM) of isolates resistant to 2 µg/mL metronidazole were 53 ± 9, 65 ± 9, 79 ± 4 and 69 ± 7 at baseline, 3, 7 and 14 days during antibiotic administration, and 57 ± 4, 64 ± 5, 62 ± 7 and 47 ± 6 at 3, 7, 14 and 90 days after antibiotic administration. At the same time points, the percentage of resistant isolates to amoxicillin was 0.5 ± 0.2, 22 ± 12, 14 ± 5 and 37 ± 11 during, and 31 ± 11, 8 ± 3, 3 ± 2 and 3 ± 0.6 after, administration. Antibiotic-resistant isolates of resistant species detected during or after therapy were also detected prior to therapy. The most prevalent resistant species in the metronidazole-treated group were: A. naeslundii 1, S. constellatus, A. naeslundii 2, S. mitis, S. oralis, A. odontolyticus, S. sanguis, and in the amoxicillin-treated group: S. constellatus, P. nigrescens, E. saburreum, A. naeslundii 1, S. oralis, P. melaninogenica and P. intermedia. Conclusions: Systemic antibiotic administration transiently increased the percentage of resistant subgingival species, but a major component of subgingival plaque remained sensitive to the agents during their administration. Antibiotic-resistant isolates of resistant species could be detected in samples both prior to and after therapy. However, % antibiotic-resistant isolates returned to baseline levels 90 days after antibiotic administration.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1034/j.1600-051X.2002.290809.x
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