Antimicrobial activity of new combined antibacterial drug based on florfenicol and doxycycline
Bacterial infections of noncontagious character is one of the most common diseases among livestock and poultry. Often an association of microorganisms is etiological factor for these diseases. In this case, actual is an introduction into clinical practice antibiotics with a broad spectrum of antimicrobial activity, which would cover the most microorganisms, causative agents of bacterial infections. One of appropriate and suitable methods that would increased the effectiveness of chemotherapy of bacterial infections is a rational use of a combination of antimicrobial agents. In the article the results of the study of antimicrobial activity of new combined antibacterial preparation, based on synthetic antibiotic florfenicol from the group amfenicols and doxycycline from the group of tetracyclines, are given. The level of bacteriostatic activity of the combination drug was compared with bacteriostatic activity of monopreparations, active ingredients in ones are separately florfenicol and doxycycline. Were determined the minimum inhibitory concentration (MIC) of the combined drug and monopreparations for gram-positive and gram-negative bacteria such as Staphylococcus aureus, Streptococcus suis, Bordetella bronchiseptica, Escherichia coli and Salmonella pullorum, isolated from biological material, took from pigs and broiler chickens with various bacterial diseases. The results showed that florfenicol and doxycycline in combined preparation act indifferently regarding isolates Staphylococcus aureus, Streptococcus suis and Escherichia coli, when every antibiotic in an combination demonstrates independent action on the organism, not different activity at their separate application. At the same time, the active ingredients of the combined drug showed a synergistic effect against the isolated strains Bordetella bronchiseptica and Salmonella pullorum, demonstrated by increasing the activity of the combination of antibacterial compounds compared to the sum of their independent effects by increasing the activity of one or both of active drug components.