Evaluation of Tetracycline and Doxycycline Activities Against some Enteric Bacteria

Abstract

This study was carried out to evaluate the activity of tetracycline and doxycycline against enteric bacteria. Five hundred and forty specimens were collected from patients suffering from different bacterial infections, 127 enteric bacteria were isolated by the used of different methods of isolation and identification, belonging to four different genera of enteric bacteria: 40 strains of E.coli, 19 strains of Klebsiella species, 37 strains of Proteus species (26 P.mirabilis, 11 P.vulgaris) and 31 strains of Salmonella species (17 S.typhi, 14 S.paratyphi). The clinical isolates were purified on selective media and identified by biochemical tests then subjected to Kirby-Bauer disc diffusion test. The result showed that 80% of E.coli were resistant , 5% were intermediate susceptibility and 15% were susceptible to tetracycline , while 82.5% of E.coli were resistant to doxycycline , 12.5% were intermediate susceptibility and 5% were susceptible, 94% of K.pneumoniae were resistant to tetracycline and 6% were intermediate susceptible, while 75% of K.pneumoniae were resistant to doxycycline, 6% were intermediate and 19% were susceptible, (100%) of K.rhinoscleromatis were resistant to tetracycline, 67% were resistant to doxycycline and 33% were susceptible . All Proteus species 100% were resistant to tetracycline and doxycycline. 82%of S.typhi were susceptible, 18% were intermediate susceptible to tetracycline and 88% of S.typhi were susceptible to doxycycline, 6% were intermediate and 6% were resistant, the result also showed that 79%of S.paratyphi were resistant, 14% were intermediate and 7% were susceptible to tetracycline, while 71.5% of S.paratyphi were resistant, 21.5%were intermediate susceptibility and 7% were susceptible to doxycycline.