Abstract
Background: Combinations of antibiotics are used to increase the therapeutic options via the simultaneous activities of two compounds. The goals of combination therapy are to resolve the bacterial infection while reducing the treatment cost. The use of kitasamycin is used frequently and in addition to other antibiotics, the desired combinations were not found. Methods: Fields strains: we use serotypes 1, 3, 5 y 7. Microbial culturing: The serotypes 1, 3, 5 y 7 was identified. Antibiotics and Reagents: The antibiotics used were kitasamycin; enrofloxacin and oxolinic acid. The following combinations were tested: a) kitasamycin with enrofloxacin; b) kitasamycin with norfloxacin; and c) kitasamycin with oxolinic acid. Preparation of bacterial suspensions: The cultures were adjusted to a concentration of 5 colony-forming units per ml (CFU/ml) using the same sterile culture medium as the diluent. Determination of the fractional inhibitory concentrations (FICs): To test each combination and their interactions and to calculate the fractional inhibitory concentration (FIC) of each antibiotic. Calculation of the index of the fractional minimum inhibitory concentration (FMIC): The FMIC index was calculated by applying the following formula: FIC index = FIC of antibiotic A/FIC of antibiotic B. Results: What was found showed that: A combination of kitasamycin and norfloxacin has been shown to have an indifferent effect. A combination of kitasamycin and enrofloxacin had antagonistic effects against all of the Actinobacillus pleuropneumoniae serotypes studied. Finally, a combination of kitasamycin and oxolinic acid had antagonist effects against serotypes 1, 3 and 5 and a synergistic effect against serotype 7. Conclusion: The “in vitro” combination Kitasamycin-Norfloxacin showed an indifferent effect, and combination Kitasamycin and Enrofloxacin demonstrated an antagonistic interaction between these two antibiotics. A combination of Kitasamycin and Oxolinic Acid had synergistic effect against serotype 7.
Highlights
Actinobacillus pleuropneumoniae is the causative agent of porcine pleuropneumonia (PP), a severe and frequently fatal disease that affects pigs of any age [1]
The addition of antibiotics to food is of little value during a pleuropneumonia outbreak, as the animals become anorexic, making it difficult for them to consume a therapeutic dose that delivers the minimum inhibitory concentration (MIC) required to eliminate the microorganism; treatment by this route does not prevent infection, and it can only reduce the severity of the clinical disease [6]
The results demonstrated an antagonistic interaction between these two antibiotics when in combination
Summary
Actinobacillus pleuropneumoniae is the causative agent of porcine pleuropneumonia (PP), a severe and frequently fatal disease that affects pigs of any age [1]. The addition of antibiotics to food is of little value during a pleuropneumonia outbreak, as the animals become anorexic, making it difficult for them to consume a therapeutic dose that delivers the minimum inhibitory concentration (MIC) required to eliminate the microorganism; treatment by this route does not prevent infection, and it can only reduce the severity of the clinical disease [6]. Combinations of antibiotics can be used to increase therapeutic options, and a common goal is to identify formulas that can resolve bacterial infections while reducing treatment costs [1] [9]. Antibiotics and Reagents: The antibiotics used were kitasamycin; enrofloxacin and oxolinic acid. A combination of kitasamycin and enrofloxacin had antagonistic effects against all of the Actinobacillus pleuropneumoniae serotypes studied.
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