Investigation of Clostridium perfringens in small-scale commercial broiler flocks in Mymensingh district of Bangladesh

Antimicrobial susceptibility and multilocus sequence typing of Clostridium perfringens isolated from yaks in Qinghai-Tibet plateau, China

Clostridium perfringens (C. perfringens) is an opportunistic pathogen that cause necrotic enteritis, food poisoning and even death in animals. In this study, we explored the prevalence, antibiotic resistance and genetic diversity of Clostridium perfringens isolated from yak in the Qinghai-Tibet plateau, China. A total of 744 yak fecal samples were collected and assessed for toxin genes, antimicrobial susceptibility and multilocus sequence typing (MLST). Results indicated that 144 out of 744 (19.35%) yak fecal samples were tested to be positive for C. perfringens, 75% (n = 108, 108/144) were C. perfringens type A, 17.36% (n = 25, 25/144) were C. perfringens type C, 2.78% (n = 4, 4/144) were C. perfringens type D, and 4.86% (n = 7, 7/144) were C. perfringens type F. In addition, 2.78% (n = 4, 4/144) of the isolates were positive for cpb2 toxin gene. Antimicrobial susceptibility testing revealed that 98.61% (142/144) of the isolates showed multiple-antibiotic resistance. According to MLST and phylogenetic tree, 144 yak-derived C. perfringens isolates had an average of 12.95 alleles and could be divided into 89 sequence types (STs) and clustered in 11 clonal complexes (CCs). The most of isolates belong to type A with a considerable genetic diversity, having Simpson index up to 0.9754. MLST and phylogenetic analysis showed that the isolates under the same clade came from multiple regions. Cross-transmission among isolates and interconnectedness were observed in the genetic evolution. According to the study, the most of the isolates exhibited broad-spectrum antibacterial resistance, diverse alleles, and multiple lethal toxin genes of C. perfringens.

Immunogenicity of a newly developed vaccine against Clostridium perfringens alpha-toxin in rabbits and cattle

Background and Aim: Clostridium perfringens type A is an anaerobic bacterium that produces four major toxins (alpha, beta, epsilon, and iota) that cause various diseases. Most of the important C. perfringens-associated diseases of farm animals are caused by alpha-toxin. This study aimed to produce a vaccine against alpha-toxin using C. perfringens type A (ATCC 13124) and investigate its potency, stability, and safety. Materials and Methods: The vaccine was formulated of its constituents for 1 h. Each milliliter of the final vaccine product contained alpha toxoid 15 lecithovitellinase activity (Lv) by adding (0.375 mL containing 40 Lv) and approximately 0.2 mL from 3% concentrated aluminum hydroxide gel, <0.001% W/V thiomersal, <0.05% W/V formaldehyde, and nearly 0.425 mL phosphate-buffered saline (pH 7.2). The vaccine efficacy was evaluated in rabbits and cattle by performing potency, stability, and safety tests. Results: The vaccine produced approximately 8.8 and 4.9 IU/mL neutralizing antibodies in rabbits and cattle, respectively. These concentrations were higher than the lowest concentration recommended by various international protocols and the United States Department of Agriculture by 2.20-fold in rabbits and 1.23-fold in cattle. Interestingly, the formulated vaccine enhanced immune responses by 1.80-fold in rabbits compared with that in cattle; the difference was statistically significant (p < 0.0001). The vaccine was stable for 30 months. In vaccinated rabbits, the body temperature slightly increased temporarily during the first 10 h of vaccination; however, the temperature difference was not statistically significant (p > 0.05). Conclusion: This study describes a manufacturing process to obtain sufficient amounts of a vaccine against C. perfringens alpha-toxin. The formulated vaccine effectively elicited a higher level of neutralizing antibody response than the international standards. Furthermore, the vaccine was found to be stable, safe, and effective in preventing C. perfringens-related diseases in rabbits and cattle. Further studies are necessary to evaluate the efficacy of this vaccine in other farm animals.