M. Feres et al., Systemic doxycycline administration in the treatment of periodontal infections - (I) - Effect on the subgingival microbiota, J CLIN PER, 26(12), 1999, pp. 775-783
Systemic doxycycline is one of the more common antimicrobial agents used in
the treatment of periodontal infections and yet little is known of its eff
ect on subgingival plaque composition during and after its administration.
The purpose of the present investigation was to evaluate changes in subging
ival plaque composition during and after 14 days of doxycycline administrat
ion. 20 subjects with adult periodontitis were randomly assigned to test (n
=10) and control (n=10) groups. The subjects received full mouth clinical a
ssessment of pocket depth, attachment level, BOP, gingival redness, suppura
tion and plaque accumulation at baseline and 90 days. All subjects received
full mouth SRP at baseline and, additionally, the test group received 100
mg doxycycline daily for 14 days. Subgingival plaque samples were taken fro
m the mesial surface of up to 28 teeth in each subject at baseline and 90 d
ays. In addition, plaque samples were taken from 2 randomly selected teeth
at 3, 7 and 14 days during and after antibiotic administration. Control sub
jects were sampled at the same time points. Counts of 40 subgingival specie
s were determined using checkerboard DNA-DNA hybridization and fluorescent
detection. Significance of differences between test and control groups was
determined at each time point using the Mann Whitney test. Significance of
changes over time within test and control groups was determined using the Q
uade test. A modest but significant reduction in mean pocket depth from bas
eline to 90 days occurred in both test and control groups. A significant de
crease in the % of sites with gingival redness occurred in the test group.
There were no significant differences in proportions between test and contr
ol groups for 33 of the test species at any time point. Test subjects exhib
ited lower proportions of 4 Actinomyces species and an increase in 3 Strept
ococcus species during antibiotic administration. After cessation of doxycy
cline, Actinomyces sp. increased while Streptococcus sp. returned to baseli
ne proportions. The relationship between these 2 genera appeared to be reci
procal; an increase in one was accompanied by a decrease in the other. Peri
odontal pathogens including B. forsythus, P. gingivalis, T. denticola and A
. actinomycetemcomitans were not significantly altered by oral administrati
on of doxycycline using conventional therapeutic dosage.