Synergistic antibacterial effects of β-Chloro-L-alanine and phosphomycin on urinary tract isolates of E. coli

Introduction: The aim of this study was the evaluation of the synergistic effect of sub-MIC doses of Phosphomycin with β-Chloro-L-alanine against urinary tract isolates of E. coli. Materials and methods: A total of 40 isolates were collected from urine specimens submitted to the clinical diagnostic Laboratories in Urmia, Iran. The amounts of MIC and MBC for Phosphomycin, β-Chloro-L-alanine or a mixture of 0.5 mM β-Chloro-L-alanine with sub-MIC doses of Phosphomycin were determined and three groups were compared. Results: Of 40 E. coli isolates, 12. 5% were susceptible to all investigated concentrations of phosphomycin and 2. 5% were resistant. The mean MIC value for phosphomycin in the other E. coli isolates was determined as 25. 7± 35. 5 µg/ mL. All of the bacterial isolates were resistant to all investigated concentrations of β-Chloro-L-alanine. Application of β-Chloro-L-alanine and phosphomycin combination decreased the MIC and MBC values in 22. 5% of the isolates. Discussion and conclusion: This study suggests that β-Chloro-L-alanine and phosphomycin combination have in vitro synergistic effect on some isolates of urinary tract E. coli.