Necrotic enteritis caused by Clostridium perfringens leads to serious economical losses to the poultry industry. There is a growing need to find effective, nontoxic, antibiotic alternatives to prevent and cure the disease. In our study, the efficacy of protected sodium butyrate at 1.5 g/kg (BP70), a Bacillus amyloliquefaciens spore suspension with 10(9) cfu/g (BAL; Ecobiol), a protected blend of essential oils (1%) at 1.5 g/kg (EO), and a combination of sodium butyrate with essential oils (1%) protected with vegetable fat at 1.5 g/kg (BP70+EO; Natesse) was investigated in an artifical C. perfringens-infection model. Body weight gain, gross pathological and histopathological lesion scores, villus lengths, and villus length:crypt depth ratio was determined and compared with the control group. Broilers infected with C. perfringens and treated with essential oils or the combination of sodium butyrate and essential oils showed significantly better BW gain (P < 0.05), increased villus length and villus length:crypt depth ratio (P < 0.001), and decreased gross pathological and histopathological lesion scores (P < 0.05) compared with the control. Sodium butyrate alone and B. amyloliquefaciens spore suspension had no beneficial effects on the course of the disease in this study. According to our results, the protected combination of sodium butyrate and essential oils, as well as the protected essential oils, can be potential candidates for the prevention and treatment of necrotic enteritis in broiler chickens.

The molecular mechanisms of resistance to fluoroquinolones, tetracyclines, an aminocyclitol, macrolides, a lincosamide, a phenicol, and pleuromutilins were investigated in Mycoplasma bovis . For the identification of mutations responsible for the high MICs of certain antibiotics, whole-genome sequencing of 35 M. bovis field isolates and 36 laboratory-derived antibiotic-resistant mutants was performed. In vitro resistant mutants were selected by serial passages of M. bovis in broth medium containing subinhibitory concentrations of the antibiotics. Mutations associated with high fluoroquinolones MICs were found at positions 244 to 260 and at positions 232 to 250 (according to Escherichia coli numbering) of the quinolone resistance-determining regions of the gyrA and parC genes, respectively. Alterations related to elevated tetracycline MICs were described at positions 962 to 967, 1058, 1195, 1196, and 1199 of genes encoding the 16S rRNA and forming the primary tetracycline binding site. Single transversion at position 1192 of the rrs1 gene resulted in a spectinomycin MIC of 256 μg/ml. Mutations responsible for high macrolide, lincomycin, florfenicol, and pleuromutilin antibiotic MICs were identified in genes encoding 23S rRNA. Understanding antibiotic resistance mechanisms is an important tool for future developments of genetic-based diagnostic assays for the rapid detection of resistant M. bovis strains.

The effect of various environmental factors on the stability of aqueous solutions of amoxicillin-clavulanic acid combination in a veterinary water-soluble powder product was investigated. In the swine industry, the combination is administered via the drinking water, where both substances are quickly decomposed depending on several environmental factors. The degradation rate of the substances was determined in solutions of different water hardness levels (German hardness of 2, 6 and 10) and pH values (3.0, 7.0 and 10.0), and in troughs made of different materials (metal or plastic). Increasing the water hardness decreased the stability of both substances, amoxicillin being more stable at each hardness value than clavulanate. Amoxicillin trihydrate proved to be most stable at an acidic pH, while increasing the pH decreased its stability (P < 0.05). Maximum stability of potassium clavulanate was experienced at neutral pH, while its decomposition rate was significantly higher at acidic and alkaline pH values (P < 0.01). The stability of the amoxicillin-clavulanic acid combination depends mainly on the less stable clavulanate, although the effect of metallic ions significantly increased the decomposition rate of amoxicillin, rendering it less stable in metal troughs than clavulanate (P < 0.05). Therefore, the amoxicillin-clavulanic acid combination should be administered to the animals in soft water, at neutral pH and in plastic troughs.

Mycotoxin contamination in feedstuffs is a worldwide problem that causes serious health issues both in humans and animals, and it contributes to serious economic losses. Deoxynivalenol (DON) and T-2 toxin (T-2) are major trichothecene mycotoxins and are known to challenge mainly intestinal barrier functions. Polyphenolic rosmarinic acid (RA) appeared to have antioxidant and anti-inflammatory properties in vitro. The aim of this study was to investigate protective effects of RA against DON and T-2 or combined mycotoxin-induced intestinal damage in nontumorigenic porcine cell line, IPEC-J2. It was ascertained that simultaneous treatment of DON and T-2 (DT2: ) for 48 h and 72 h reduced transepithelial electrical resistance of cell monolayer, which was restored by 50 μmol/L RA application. It was also found that DT2 for 48 h and 72 h could induce oxidative stress and elevate interleukin-6 (IL-6) and interleukin-8 (IL-8) levels significantly, which were alleviated by the administration of RA. DT2 administration contributed to the redistribution of claudin-1; however, occludin membranous localization was not altered by combined mycotoxin treatment. In conclusion, beneficial effect of RA was exerted on DT2-deteriorated cell monolayer integrity and on the perturbated redox status of IPEC-J2 cells.

Mycoplasma hyopneumoniae infections are responsible for significant economic losses in the swine industry. Commercially available vaccines are not able to inhibit the colonisation of the respiratory tract by M. hyopneumoniae absolutely, therefore vaccination can be completed with antibiotic treatment to moderate clinical signs and improve performances of the animals. Antibiotic susceptibility testing of M. hyopneumoniae is time-consuming and complicated; therefore, it is not accomplished routinely. The aim of this study was to determine the in vitro susceptibility to 15 different antibiotics of M. hyopneumoniae isolates originating from Hungarian slaughterhouses and to examine single-nucleotide polymorphisms (SNPs) in genes affecting susceptibility to antimicrobials. Minimum inhibitory concentration (MIC) values of the examined antibiotics against 44 M. hyopneumoniae strains were determined by microbroth dilution method. While all of the tested antibiotics were effective against the majority of the studied strains, high MIC values of fluoroquinolones (enrofloxacin 2.5 μg/ml; marbofloxacin 5 μg/ml) were observed against one strain (MycSu17) and extremely high MIC values of macrolides and lincomycin (tilmicosin, tulathromycin and lincomycin >64 μg/ml; gamithromycin 64 μg/ml; tylosin 32 μg/ml and tylvalosin 2 μg/ml) were determined against another, outlier strain (MycSu18). Amino acid changes in the genes gyrA (Gly81Ala; Ala83Val; Glu87Gly, according to Escherichia coli numbering) and parC (Ser80Phe/Tyr; Asp84Asn) correlated with decreased antibiotic susceptibility to fluoroquinolones and a SNP in the nucleotide sequence of the 23S rRNA (A2059G) was found to be associated with increased MIC values of macrolides. The correlation was more remarkable when final MIC values were evaluated. This study presented the antibiotic susceptibility profiles of M. hyopneumoniae strains circulating in the Central European region, demonstrating the high in vitro efficacy of the tested agents. The observed high MIC values correlated with the SNPs in the examined regions and support the relevance of susceptibility testing and directed antibiotic therapy.