Use of Different Antibiotic Combinations against Fluoroquinolone-Resistant Salmonella enterica from Humans in Egypt

EMERGENCE of antibiotic resistance by pathogenic Salmonella spp. is a worldwide problem. Antibiotic combination was used as a clinical cure to solve the problem. Over one and a half years , one hundred gastroenteritis bacterial pathogens were collected from three Egyptian hospitals from fecal and blood sources. 58% Salmonella isolates were purified and identified using phenotyping and serotyping techniques. Out of the 58% Salmonella spp., 41.4% represented S. Typhimurium, 27.6% S. Enteritidis, 5.2% S. Typhi, 3.4 % S. ParatyphiA, 3.4 % S. Paratyphi B and 19.0% other Salmonella. A total of 36 (62%) out of 58 Salmonella spp. were fluroquinolone resistant by disk diffusion method. Resistance of five Salmonella strains to the fluroquinolone group was confirmed by MICs values. The level of these values was from 32 - >512 µg/ml, which is higher than those recommended by CLSI. Seventy-five combined microtitre checkerboards were performed on the five fluroquinolone multiresistant Salmonella strains to assess the potential for combination therapy. No antagonism was observed with any combination. Synergy and additivity were achieved with 41.4% and 58.6%, respectively. Time-kill synergy was more often seen at 24hr. There is 100%, 50% and 40% agreement between time-kill and checkerboard results for three Salmonella strains. Resistant Salmonella has increased in Egypt. Fluroquinolone combination with β-lactams (gentamycin, amikacin) and aminoglycosides (cefotaxime) were effective in the treatment of resistant Salmonella Typhimurium, Enteritidis and Typhi.