Effects of doxycycline, metronidazole and their combination on Candida species colonization of the human oropharynx, intestinal lumen and vagina.
Maraki S1, Margioris AN, Orfanoudaki E, Tselentis Y, Koumantakis E, Kontoyiannis DP, Rovithi M, Samonis G.
The present study reports about the effect of doxycycline and/or metronidazole on colonization by Candida organisms of the human gastrointestinal (GI), oropharyngeal tract and vagina. Treatment with doxycycline or metronidazole for 10 days increased, but not significantly, the GI, oropharyngeal or vaginal colonization by Candida species. The combination of doxycycline and metronidazole, used for the same period, caused a significant increase of 2.5 log10 CFU/g of stools (mean) colonization by Candida. Likewise, 2 out of 9 patients treated with the combination had substantially increased colonization of their vagina by Candida species. This effect, however, could not be expressed statistically due to the semiquantitative nature of the vaginal cultures. In contrast, the combination did not increase oropharyngeal colonization. In conclusion, doxycycline and metronidazole as monotherapies, did not increase significantly Candida colonization in the cavities examined. The combination of doxycycline and metronidazole had a substantial effect, increasing the GI and vaginal colonization by Candida organisms.
The aim of this study was to study the effects of metronidazole on the establishment of oral candidosis and Candida albicans colonization in the oral cavity of rats. Forty-eight male rats, negative for yeasts in the oral cavity, were used in the study. The rats were inoculated with a suspension of Candida albicans and treated with metronidazole or plain water (control group). The rats of the candidosis experimental group were sacrificed 7, 15, or 30 days after inoculation and their tongues were analyzed by light microscopy. Colonization by Candida albicans was evaluated 1, 2, 5 and 7 days after inoculation and progressively at 15-day intervals, with a total of 18 collections. The results demonstrated the development of candidosis on the tongue dorsum was similar between the Control and Metronidazole groups for each sacrifice period. However, the colonization results showed that yeasts were recovered in the Metronidazole group in greater numbers than in the Control group after the 37th day of the experiment (6th collection). According this, the long term metronidazole therapy favored the colonization of C. albicans in the oral cavity of rats.
Metronidazole is very active against the anaerobic flora that is considered the protective bacterial flora.