Antimicrobial susceptibility of bacterial isolates from 233 horses with musculoskeletal infection during 1979-1989.

This research investigates the antimicrobial susceptibility of bacterial infections in horses, specifically musculoskeletal infections resulting from fracture repair. The study found that Amikacin was the most effective antibiotic against the wide range of bacteria isolated.

Study Purpose and Methodology

• The researchers analyzed bacterial culture and susceptibility results obtained from 233 horses that had developed septic arthritis/tenosynovitis or osteomyelitis following fracture repair.
• The effectiveness of antibiotics was assessed based on their ability to render a certain percentage of the bacterial isolates susceptible — antibiotics were deemed ‘highly effective’ if they could make 85% or more of the isolates susceptible, ‘effective’ if they could affect 70-84.9% of isolates, and ‘ineffective’ if they worked on less than 70% of the isolates.

Findings of the Study

• The study documented the occurrence of 424 types of bacterial isolates. The majority of these were aerobic or facultative bacteria, while a small percentage was anaerobic bacteria.
• Enterobacteriaceae were the most common type of bacteria identified, constituting 28.8% of the isolates. Other types of bacteria isolated included non-beta-haemolytic streptococci, coagulase-positive staphylococci, beta-haemolytic streptococci, and coagulase-negative staphylococci.
• The study found that penicillin and ampicillin were highly effective against beta-haemolytic streptococci, but not against other types of bacteria, while ampicillin was proven to be no more effective than penicillin against most bacteria.
• Overall, Amikacin emerged as the most effective antibiotic against the wide range of bacteria isolated in this study. It was highly effective against coagulase-positive staphylococci, Enterobacteriaceae, and Pseudomonas and also showed effectiveness against coagulase-negative staphylococci and Actinobacillus.
• Other antibiotics, such as gentamycin and kanamycin, had more limited effectiveness, and kanamycin was found to be ineffective against all bacteria with the exception of Actinobacillus.

Implications of the research

• The results suggest that Amikacin could be a highly effective antibiotic for treating a wide range of post-operative musculoskeletal bacterial infections in horses. Other antibiotics like penicillin, ampicillin, and cephalothin also showed some effectiveness against certain types of bacteria.
• The findings of this research could serve as a guide for veterinarians and animal health professionals in choosing the most effective antimicrobials for treating such infections in horses.