| Objective:Salmonella infection and drug resistance has become a global concern of public health,and the Salmonella strains were increasingly detected in diarrhea patients,poultry and meat.Now,Salmonella strains were also detected in the feces of healthy practitioners who are monitored by the state.The prevalence of Salmonella among health practitioners is of epidemiological significance.However,there are few studies on Salmonella strains carried by health practitioners,and the related drug resistance and drug resistance gene information is less.In this study,we aimed to reveal the epidemiological characteristics and drug resistance of Salmonella strains carried by health practitioners in Yulin,and to put forward suggestions for the prevention and control of Salmonella infection.Methods:The fecal samples of health practitioners in Yulin were selected for the serology analysis and drug resistance study of 3993 Salmonella strains separated from 2013 to2019.First,serology experiment was carried out to determine the serotype,and then drug resistance experiment of 29 antimicrobial agents was carried out to clarify the drug resistance of Salmonella.What’s more,nucleic acid extraction experiment was carried out on the multi-drug resistant Salmonella strains,and the whole genome sequencing was conducted to analyze the carrying status of quinolone,ESBL and mcr genes.Result:（1）Characteristics of Salmonella carried by health practitioner in YulinA total of 3,993 strains of Salmonella were carried by health practitioner in Yulin from 2013 to 2019.Among them,the positive rate of Salmonella in 2013 was 1.38%（275/19959）,2.13%（444/20845）in 2014,2.32%（536/23103）in 2015,1.93%（443/22937）in 2016,2.15%（697/32482）in 2017,1.59%（649/40941）in 2018,1.90%（949/50010）in 2019.The mean detection rate was 1.90%（3993/210277）.There was no statistic difference in Salmonella detection rate among different genders（P>0.05）.The detection rate of Salmonella in different age groups was different（P<0.05）.There was no statistic difference in the detection rate of Salmonella among 30～,40～and 50～69 groups.Compared with the 18～group,the Salmonella detection rate in the40～group was higher,and there was a statistic difference（P<0.05）.The Salmonella detection rate in the 50～69 age group was higher,and there was a statistic difference（P<0.05）.By comparing the detection rate of Salmonella in the two types of occupations,the detection rate of food practitioners was 2.02%（3471/171990）,and that of public practitioners was 1.36%（522/38287）.There was a statistic difference in the detection rate of Salmonella between the two types of occupations（P<0.05）.Salmonella detection rate of food practitioners is higher than that of public practitioners.Using logistic regression model to analyze the influencing factors of Salmonella detection rate,the dependent variable whether for Salmonella detection in gender,age,occupation type as the independent variable is analyzed,the results showed that in different gender and age of Salmonella detection rate there is no statistical significance.Salmonella detection rate differences between two types of occupations（P<0.05）,and the risk of carrying Salmonella are 1.492 times than public employees.（2）Serotypes of Salmonella carried by health practitioners in YulinThe category of Salmonella serotypes carried by health practitioners in Yulin were complex and diverse.From 2013 to 2019,106 serotypes of Salmonella were isolated from food practitioners,51 serotypes of Salmonella were isolated from public practitioners,and 47 serotypes of Salmonella were isolated from both food and public practitioners.There are 57 serotypes only appearing in the food practitioners,of which more than 5 strains include 14 strains of S.Sao Paulo,9 strains of S.Barrely,9 strains of S.Wandsworth,6 strains of S.Liverpool,6 strains of S.Havana,5 strains of S.cremieus,the others are below 5 strains.The top of 20 serotypes that accounted for more than 10%of the total from 2013 to 2019 are S.Rissen,S.Typhimurium,S.Agona,S.Derby,S.Corvallis,S.Harar,S.Senftenberg,S.Kottbus,S.Albany,S.Stanley,S.Kentucky,S.Turkey,S.Weltevreden,S.London,S.Potsdam,S.Anatum,S.Enteritis,S.Mbandaka,S.Thompson and S.Cerro.The proportion of dominant serotypes in food practitioners was large,and fluctuation of serotypes greatly among different years,the proportion of serotypes in public practitioners was homogeneous distribution.Comparison results of the positive rate of the top 20 serotypes showed that the positive rate of S.Typhimurium,S.Agona,S.Derby,S.Rissen,S.Kentucky,S.London,S.Weltevreden,S.Senftenberg were different among food practitioners and public practitioners（P<0.05）,and the positive rate of Salmonella among food practitioners was higher than that of public practitioners.（3）Drug resistant phenotype of Salmonella carried by health practitioners in YulinThe results of Salmonella drug resistance experiments carried by health practitioners in Yulin showed that the drug resistance rate of aminoglycosides,penicillins,carbapenems,quinolones and third-generation cephalosporins was less than30%.Amikacin was sensitive before 2018,and resistance appeared in 2019.Drug resistance rate of moxifloxacin increased gradually with the year,and ceftriaxone was close to 30%in 2016.The drug resistance rate of tetracycline,cefoxitin and cefuroxime were serious,and the drug resistance rate of chloramphenicol is also increasing year by year,so they should be used cautiously in the clinical.The drug resistance spectrum of health practitioners in Yulin is complex,with the number of antibiotic resistances generally concentrated in 3-7 kinds.With the increase of years,more complex drug resistance spectrum began to appear,and even one strain resistant to 20 antibiotics.The drug resistance of aminoglycoside,tetracycline,penicillin,carbapenem,quinolones between food and public practitioners is no statistical difference,but the cefoxitin,cefazolin and ceftriaxone are different（P<0.05）.The drug resistance of cefazolin and cefoxitin in food practitioners higher than public practitioners.Other antibiotics,for example,Aztreonam,Chloramphenicol and Fosfomycin,the drug resistance of them has differences（P<0.05）,and food practitioners is higher than public practitioners.The multiple-drug resistance rate of health practitioners in Yulin from 2013 to 2019 was statistically analyzed,and the total multiple-drug resistance rate fluctuated between 37.3%to 56.8%,indicating that the multiple-drug resistance was serious.The multiple drug resistance rate of food practitioners was 46.24%（1605/3471）,and the multiple drug resistance rate of public practitioners was 41.57%（217/522）.Different serotypes have different multi-drug resistance.Among the top 20serotypes,13 Salmonella serotypes,including S.Typhimurium,S.Delby,S.Argon and so on have a multi-drug resistance rate of more than 30%,and the average multi-drug resistance of seven species,including S.Stanley S.Weitai Freden does not exceed 30%.There was a statistic different in the multiple-drug resistance rate between the two occupations（P<0.05）.There were 652 drug resistance spectrum combinations of Yulin health practitioners,and 20 kinds of multiple-drug resistance spectrum with the number of strains greater than 10 strains.The highest frequency was Chloramphenicol,Tetracycline,Trimethoprim and Sulfamethoxazole resistance.There were 610 kinds of drug resistance spectrum combinations among food practitioners,and 19 kinds of dominant multiple-drug resistance spectrum with the number of strains greater than 10strains.The highest combination frequency was Chloramphenicol,Tetracycline,Trimethoprim and Sulfamethoxazole resistance.There were 121 kinds of drug resistance spectrum of public practitioners,and there were three dominant multiple-drug resistance spectrum with the number of strains greater than 10 strains.The highest combination frequency was Chloramphenicol,Tetracycline and Trimethoprim-Sulfamethoxazole resistance.Fifty-nine serotypes showed a multi-drug resistance spectrum,among which S.Typhimurium,S.Derby,S.Rissen,S.Agona,S.Corvallis,S.London,S.Kentucky,S.Albany,S.Turkey,S.Thompson and S.Gold Coast,etc.Different serotypes showed different drug resistance rates to the same antimicrobials.S.Derby had the highest resistance rate to Ciprofloxacin,up to 66.7%.The resistance trend of S.Typhimurium to Ciprofloxacin was consistent with that of S.Derby.The other three serotypes had low resistance rates to Ciprofloxacin.The drug resistance rate of the five serotypes to Norfloxacin was still at a low level.Compared with the other four Salmonella serotypes,S.Typhimurium showed higher drug resistance rates and more severe drug resistance to Cefoperazone-Sulbactam,Ceftazidime and Ceftriaxone.（4）Genotypes of Salmonella carried by health practitioners in YulinWhole-genome sequencing results show that from 2013 to 2019,multi-drug-resistant Salmonella were carried by health service practitioners in Yulin contained 17quinolone-resistant genes.aac（6’）-Ib-cr,qnr S1,oqx A,oqx B,qnr B6 and qnr S2 genes appear every year.qep A,qnr B60,qnr B19,qnr S10 and qnr S3 genes are not common and have a relatively low proportion.There was no statistic difference in the carrying rate of quinolone gene between the two practitioners（P>0.05）.The multi-drug resistant Salmonella carried by Yulin health service workers contains ESBL and mcr genes.A total of 51 ESBL genes were detected,of which bla TEM-1B,bla OXA-1,bla TEM-1A,and bla CARB-2 appeared for 7 years,and other genotypes accounted for a relatively low proportion.Among them,the bla TEM-1A gene detection rate is different between the two occupations（P<0.05）,and the detection rate of employees in public places is higher than that of food employees.The overall carrier rate of the multi-drug resistant Salmonella mcr-like gene carried by Yulin health service employees is less than 5%,and it has shown a downward trend from 2017 to 2019.The genotypes are mcr-1.1,mcr-1.6 and mcr-9,which mainly carry mcr-1.1 gene.There was no statistic difference in the detection rate of the three mcr genes between the two occupations（P>0.05）.The 13 Salmonella strains also have quinolone,ESBL and mcr genes,mainly the coexistence of bla OXA-1,mcr-1.1,oqx A and oqx B genes,all of which were from food practitioners.Conclusion:After 7 years of monitoring of Salmonella carried by health practitioners in Yulin,Salmonella was detected seriously among health practitioners in Yulin.Compared with public practitioners,the Salmonella serotypes carried by food practitioners was more complex and more resistant to drugs.The colistin ban has a good effect on the colistin resistance of Salmonella.Therefore,the monitoring of Salmonella in health practitioners,especially in food practitioners,should be strengthened. |
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