Characterization of Genotypes and Drug Resistances on Staphylococcus aureus from Chicken during Processing

In order to explore the enterotoxin gene distribution, molecular typing and drug resistance of Staphylococcus aureus during the processing of chicken products, samples were taken from the production and processing process of a chicken products processing factory. The Staphylococcus aureus was isolated and identified by DNA extraction and PCR amplification of nuc gene, and then the distribution of enterotoxin gene was analyzed to obtain the bacteria with toxin gene multi locus sequence typing (MLST) and drug resistance were studied. Results showed that, 38 strains of Staphylococcus aureus were isolated from 260 samples (including 24 strains carrying enterotoxin gene), and the detection rate was 63.16%. A total of 7 enterotoxin genotypes were detected, with the highest sed carrying rate 60.53%, followed by seg (26.32%), see (21.05%), sei (18.42%), sec (10.53%), sea (7.89%), and seh (5.26%). Among these 24 strains carrying the enterotoxin gene, there was 14 strains (36.84%) carrying two or more enterotoxin genes. And these 24 strains were divided into 3 ST genotypes of the MLST, including ST7 (66.67%), ST5 (20.83%) and ST464 (12.5%). The resistance against antibiotics of the 38 isolates showed that the strains were sensitive to vancomycin (100%), and more than half of the strains were resistant to other antibiotics, such as penicillin G (86.84%), ciprofloxacin (60.53%), clindamycin (55.26%), and tetracycline (52.63%). The multi-drug resistance rate of the strain reached 65.78%, among which Staphylococcus aureus strains resistant to 3 antibiotics accounted for 18.42%, resistant to 4 antibiotics accounted for 15.79%, resistant to 5 antibiotics accounted for 23.68%, and resistant to 6 antibiotics accounted for 7.89%. These results indicated that there were contamination of Staphylococcus aureus in chicken processing, and the strains carried multiple types of enterotoxin genes, as well as multiple drug resistance.