Kill rate of mastitis pathogens by a combination of cefalexin and kanamycin

• Published in: Journal of applied microbiology 2011, Vol.110 (1), p.184-190
• Main Authors: Maneke, E, Pridmore, A, Goby, L, Lang, I
• Format: Article
• Language: English
• Subjects: Animals; Anti-Bacterial Agents - therapeutic use; Anti-Bacterial Agents - toxicity; antibiotic treatment; Bacterial Infections - drug therapy; Biological and medical sciences; Cattle; Cephalexin - therapeutic use; Cephalexin - toxicity; cow; Drug Therapy, Combination; drugs; Escherichia coli; Escherichia coli - drug effects; Female; Fundamental and applied biological sciences. Psychology; kanamycin; Kanamycin - therapeutic use; Kanamycin - toxicity; kill kinetics; Kinetics; mastitis; Mastitis, Bovine - drug therapy; Mastitis, Bovine - microbiology; Microbiology; pathogens; Staphylococcus aureus; Staphylococcus aureus - drug effects; Streptococcus - drug effects; Streptococcus agalactiae; Streptococcus agalactiae - drug effects; Streptococcus dysgalactiae; Streptococcus uberis
• ISSN: 1364-5072; 1365-2672
• DOI: 10.1111/j.1365-2672.2010.04876.x

Aim: To assess the bacterial killing rate produced by a combination of cefalexin and kanamycin at two different concentration ratios. Methods and Results: Time-kill kinetics of cefalexin and kanamycin, individually and in combination, were determined against one strain each of Escherichia coli, Staphylococcus aureus, Streptococcus agalactiae, Streptococcus dysgalactiae and Streptococcus uberis. The combination was tested using two fixed ratios (cefalexin : kanamycin ratios of 1·25 : 1 and 1 : 2·3) and two concentrations of each ratio. Time-kill curves produced with either ratio were quite similar. Against most bacterial species, higher concentrations produced faster kill. In all cases, the combination of cefalexin and kanamycin showed faster and greater kill at lower antibiotic concentrations than those observed with either drug alone. Conclusions: The combination of cefalexin and kanamycin results in a fast initial killing of major mastitis pathogens at both concentration ratios. Significance and Impact of the Study: The combination of cefalexin and kanamycin achieved rapid bacterial kill at concentrations and ratios that can be achieved in vivo following intramammary infusion of a mastitis treatment.