| Although the scale of intensive farming of dairy cows in Shandong continues to increase,some farms suffer from poor sanitation.It not only promotes the growth of environmental microorganisms,but also endangers the health of dairy cows,reduces production performance,and damages the welfare of dairy cows.In order to prevent bacterial diseases of dairy cows in the farm,the farmers will use antibiotics for a long time during the breeding process.This may lead to the continuous accumulation and evolution of antibiotic resistance and resistance genes in bacteria from the environment,and threatening the dairy industry and milk safety.However,there have been few reports so far on the investigation of bacterial resistance to antibiotics and resistance genes in dairy farm environments in Shandong Province.In this study,in order to understand the distribution and antibiotic resistance of bacteria in the intensive dairy framing environment,the bacteria isolated from the dairy farm environment were identified by MALDITOF MS,and the antibiotic resistance were detected by the dilution broth method,and use the PCR to detect the antibiotic resistance genes of the isolates.In this study,150 environmental samples were collected from 5 intensive dairy farms in Taian,Dongying and Qingdao,and 228 bacterial strains were isolated from it.39 strains were isolated from Tai’an,61 strains were isolated from Dongying,and 128 strains were isolated from Qingdao,and the bacterial species were determined by MALDI-TOF MS.The results showed that the types and distribution of bacteria varied greatly,and the number of bacterial isolates in the milking parlor was far less than that in the bed and sports field except in Tai’an.Psychrobacter sp,Glutamicibacter arilaitensis and Glutamicibacter mysorens were detected in the three regions.Among them,Glutamicibacter arilaitensis is widely present in every dairy farm.Among the 228 isolated strains,there were 66 strains of pathogenic bacteria recorded in literature,accounting for 28.95% of the total.According to the broth microdilution method recommended by the US CLSI2020 antimicrobial susceptibility test standard,10 kinds of 7types of antibiotic susceptibility tests were carried out on the isolates,which contains β-lactams,tetracyclines,aminoglycosides,sulfonamides,polypeptides,quinolones and lincosamides.The results show that the resistance to lincomycin and sulfadiazine is as high as 91% and 88%,and only 4 antibiotics are less than 30%.Among them,levofloxacin and doxycycline resistance are the lowest at 4% and 9%.Antibiotic susceptibility results showed that 78 strains of bacteria are resistant to more than 2 types of antibiotics,including 48 strains of multidrug-resistant bacteria;a total of 69 isolates are insensitive to more than 3 types of antibiotics,and 18 strains are resistance to more than 5 types of antibiotics.Through PCR method,we detected the resistance genes of 66 strains of pathogenic bacteria,including carbapenems(bla NDM-1,blakpc),lincosamines(lnu B),tetracyclines(tet M),aminoglycosides(ant(4′′)la,aph(2′)-Ic),sulfonamides(sul1),quinolones(qnr S),polymyxins(mcr-1).The results shows that the detection rate of 3 ARGs is higher than 30%,among which sul1 is the highest at 67%,and 3ARGs are not detected.In summary,this study determines the species and distribution of bacteria from partial areas and partial dairy farm environments,then the sensitivity of bacteria to antibiotics and the carrying of ARGs are detected.We find that a large number of bacterium have a tendency to develop and spread multi-drug resistance.This study not only provides clinical data for safeguarding cow health and cow welfare,but also provides data reference for the promotion of intensive farming of dairy cows,which could prevents the dairy cow diseases and controls the antibiotic-resistant pathogens at a low level.It is recommended that farmers should monitor the evolution and spread of bacterial strain resistance during the daily intensive breeding,and strengthen the daily cleaning of the cowshed. |
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