RESUMEN
Sensitivity of microflora to tetracycline, oxytetracycline, chlortetracycline and doxycicline was studied. A total of 237 pure cultures of Strep. viridans (54), beta-hemolytic streptococci (27), pathogenic staphylococci (52), non-pathogenic staphylococci (53) and Coli bacteria (51) were tested with the agar-diffusion method using standard discs. Doxycicline was most active and chortetracycline was least active. The maximum sensitivity to doxycicline was found in beta-hemolytic streptococci (85.4%) and the minimum sensitivity to that antibiotic was found in Coli bacteria (39.2%) and Strep. viridans (35.6%), which was superior to that with respect to the other tetracyclines. Coincidence of the clinical effect with the microflora sensitivity and high percentage of sensitivity to doxycicline among Staph. aureus, which is important in treatment of severe infections caused by the organism were observed.