ABSTRACT
Staphylococci is an opportunistic bacterial population that is permanent in the normal flora of milk and poses a serious threat to animal and human health with some virulence factors and antibiotic-resistance genes. This study was aimed at identifying staphylococcal species isolated from raw milk and to determine hemolysis, biofilm, coagulase activities, and beta-lactam resistance. The raw milk samples were collected from the Düzce (Türkiye) region, and the study data represent a first for this region. The characterization of the bacteria was performed with MALDI-TOF MS and 16S rRNA sequence analysis. The presence of coa, icaB, blaZ, and mecA was investigated with PCR. A nitrocefin chromogenic assay was used for beta-lactamase screening. In this context, 84 staphylococci were isolated from 10 different species, and the dominant species was determined as S. aureus (32.14%). Although 32.14% of all staphylococci were positive for beta hemolysis, the icaB gene was found in 57.14%, coa in 46.42%, mecA in 15.47%, and blaZ in 8.33%. As a result, Staphylococcus spp. strains that were isolated from raw milk in this study contained some virulence factors at a high level, but also contained a relatively low level of beta-lactam resistance genes. However, considering the animal-environment-human interaction, it is considered that the current situation must be monitored constantly in terms of resistance concerns. It must not be forgotten that the development of resistance is in constant change among bacteria.
ABSTRACT
There is an endless demand for livestock-originated food, so it is necessary to elucidate the hazard points for livestock breeding. Pathogens are one of the hazard points that threaten the biosecurity of farm-animal breeding and public health. As a potential foodborne pathogen, Aliarcobacter is a member of the intestinal microbiota of farm animals with and without diarrhea. Aliarcobacter spp. are capable of colonizing livestock intestines and are transmitted through the feces. Hence, they endanger slaughterhouses and milk products with fecal contamination. They also have other, rarer, vertical and horizontal transmission routes, including the offspring that abort in farm animals. Gastrointestinal symptoms and abort cases demonstrate potential financial losses to the industry. Viewed from this perspective, the global circulation of farm-animal products is a significant route for zoonotic agents, including Aliarcobacter. In the last decade, worldwide prevalence of Aliarcobacter in fecal samples has ranged from 0.8% in Italy to 100% in Turkey. Furthermore, antibiotic resistance is recognized as a new type of environmental pollutant and has become a hot topic in animal breeding and the food industry. Increasing antibiotic resistance has become a significant problem impacting productivity. The increase in antimicrobial resistance rates in Aliarcobacter is caused by the misuse of antimicrobial drugs in livestock animals, leading to the acquiring of resistance genes from other bacteria, as well as mutations in current resistance genes. The most resistant strains are A. butzleri, A. cryaerophilus, and A. skirrowii. This review analyzes recent findings from the past decade on the prevalence of Aliarcobacter in the intestinal microbiota and the current effective antibiotics against Aliarcobacter. The paper also highlights that A. cryaerophilus and A. skirrowii are found frequently in diarrheal feces, indicating that Aliarcobacter should be studied further in livestock diarrheal diseases. Moreover, Aliarcobacter-infected farm animals can be treated with only a limited number of antibiotics, such as enrofloxacin, doxycycline, oxytetracycline, and gentamicin.
