| In recent years,with the continuous development of China’s economy and the change of people’s diet structure,the number of modern livestock and poultry farms is also increasing.The main mode of these farms is intensive and factory farming.The frequency and total amount of antibiotics used in the breeding process also increase rapidly,and the induced antibiotic-resistant bacteria pose a great threat to the ecological environment and human health.In this study,staphylococcus aureus,a typical antibiotic resistant bacteria,was studied.The subjects collected nasal cavity samples of farm workers in Beijing,hebei and heilongjiang,nasal cavity samples of community workers and faeces samples of farm animals.The antibiotic resistance test of 17 kinds of isolated staphylococcus aureus was conducted by k-b drug-sensitive slip method,and the genetic typing of staphylococcus aureus was studied by staphylococcus aureus gene polymorphism typing(Spa typing)and multi-site sequence analysis(MLST typing).The main conclusions are as follows:(1)After systematic screening and identification,a total of 48 strains of staphylococcus aureus were selected from nasal cavity samples of farm workers,faeces of farm animals,and nasal cavity samples of community workers.33 strains were isolated from the nasal samples of farm workers,including 19 strains in the nasal cavity of chicken farm workers,10 strains in the nasal cavity of pig farm workers and 4 strains in the nasal cavity of pigeon farm workers.Four strains were isolated from the feces samples,including two strains of cow feces and two strains of chicken feces.11 strains were isolated from nasal samples taken from the community.A total of 28 strains of MRSA were screened from nasal cavity samples of farm workers,farm animal feces and nasal cavity samples of community workers.24 strains were isolated from the nasal samples of farm workers,including 18 strains in the nasal cavity of chicken farm workers,4 strains in the nasal cavity of pig farm workers and 2 strains in the nasal cavity of pigeon farm workers.4 strains were isolated from the feces samples,including two strains of cow manure and two strains of chicken manure.(2)Both staphylococcus aureus and MRSA isolated in this study were completely resistant to ampicillin.All of them were highly resistant to penicillin,streptomycin,erythromycin,ciprofloxacin,norfloxacin,tetracycline and clindamycin,and the drug resistance rate was above 90%.Both had relatively high drug resistance to doxycycline and the drug resistance rate was above 40%.The drug resistance rate of cefoperazone and gentamicin was below 25%.All were highly sensitive to sulfamethoxazole and chloramphenicol,and completely sensitive to amikacin,vancomycin and rifampicin.Both staphylococcus aureus and MRSA showed high resistance to-lactam,macrolides,quinolones,tetracycline and lincomycin antibiotics.All of them were highly sensitive to aminoglycosides,sulfa and chloramphenicol antibiotics.Both were completely sensitive to peptides and rifamycin antibiotics.Overall,MRSA was more resistant to different types of antibiotics than staphylococcus aureus.(3)Three Spa types were detected,including t034,t899 and t011.The spa type of staphylococcus aureus and MRSA isolated from the nasal cavity of chicken farm workers,the nasal cavity of community workers,cow manure and chicken manure was t034.The proportion of staphylococcus aureus t899,t034 were 90.91%,9.09% respectively and MRSA were t899,in the nnasal cavity of pig farm workers.The spa type of staphylococcus aureus and MRSA isolated from the nasal cavity of the pigeon farm workers were both t011.Spa types of isolated staphylococcus aureus and MRSA have a certain correlation with their resistance to 17 kinds of antibiotics.A total of 5 ST types were detected by MLST typing,including ST398,ST5,ST59,ST10 and ST9.The proportion of ST398,ST5,ST59 and ST10 in the nasal cavity of chicken farm workers staphylococcus aureus was 52.63%,15.79%,10.53%,21.05%,and MRSA was 50%,16.67%,11.11% and 22.22%.Staphylococcus aureus and MRSA isolated from the nasal cavity of pig farm workers were both ST9.Staphylococcus aureus and MRSA isolated from the nasal cavity of the workers were ST398.ST398 and ST59 were 81.82% and 18.18% respectively in the nasal cavity samples of community workers.Staphylococcus aureus and MRSA isolated from cow and chicken feces were ST398.The ST type of isolated staphylococcus aureus and MRSA has a certain correlation with their resistance to 17 kinds of antibiotics.The results of this study can provide a practical basis for the assessment of the harm of staphylococcus aureus to the surrounding human beings and the environment and the formulation of corresponding control measures. |
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