| ObjectivesTo identify the main epidemic species of Enterobacteriaceae and Enterococcus bacteria in the feces of migratory birds in Guangzhou,and explore the resistance of bacteria to common antibiotics,and analyze the main resistance genes carried by migratory birds,provide scientific basis for evaluating the capability of migratory birds in preserve,carrying and spreading antibiotic resistant bacteria and antibiotic resistant genes.Methods393 samples of bird feces were collected from Nansha Wetland Park in Guangzhou,in 2019.Bacteria were cultured,separated and identified in the Laboratory of the Microbiology Laboratory of Guangzhou Center for Disease Control and Prevention,and the strains of the isolates were clarified.Drug susceptibility test board was used to detect the common antibiotic resistance of Enterobacteriaceae and Enterococcus bacteria.Polymerase Chain Reaction（PCR）was used to amplify ESBLs-related resistance genes in Enterobacteriaceae,and van and tet resistance genes in Enterococcus bacteria,and pulse field gel electrophoresis was performed.The target band are sequenced,which are compared with BLAST.Result（1）From January to December 2019,this study went to Guangzhou Nansha Wetland Park to collect migratory bird feces every month.A total of 393 samples were collected.59 strains of Enterobacteriaceae were obtained with a detection rate of15.01%（59/393）.There are 12 types of bacteria,including 36 strains of Pantoea agglomerans（61.02%）,4 strains of Escherichia coli（6.78%）,and 3 strains of Klebsiella pneumoniae（5.08%）.7 strains of Carbapenem-resistant Enterobacteriaceae（CRE）were detected,including one strain of Carbapenem-resistant Klebsiella pneumoniae（Carbapenem-resistant Klebsiella pneumoniae,CRKP）.（2）79 strains of Enterococcus bacteria were obtained,with a detection rate of20.10%（79/393）,and a total of 8 types.Among them,29 strains（7.12%）of Enterococcus faecalis,28 strains（7.38%）of Enterococcus faecium,and 10 strains（2.54%）of Enterococcus pluvialis.4 strains of Vancomycin-resistant Enterococcus（Vancomycin-Resistant Enterococcus,VRE）were detected.（3）Among 59 strains of Enterobacteriaceae,53 strains of resistant bacteria were detected,with a detection rate of 89.83%.The three antibiotics with the highest resistance rate among Enterobacteriaceae were cefazolin（48 strains,81.36%）;sulfisoxazole（31 strains,52.54%）;and ampicillin（26 strains,44.07%）.Among the drug-resistant enterobacteriaceae,the three most common drug resistance spectrums are G（β-lactams）（15 strains,25.42%）,G-S-Q（β-lactams-sulfonamides-quinolones）（13 Strains,22.03%）,G-S（β-lactams-sulfa）（8 strains,13.56%）.（4）Among 79 strains of Enterococcus bacteria,55 strains of resistant bacteria were detected,with a detection rate of 69.62%.The three antibiotics with the highest resistance rate among Enterococcus bacteria are tetracycline（43 strains,54.43%）,erythromycin（38 strains,48.10%）,and streptomycin（high concentration）（14 strains,17.72%）.Among the resistant Enterococcus bacteria,the three most common resistance spectrums are T（tetracycline）（10 strains,12.66%）,E-T（7 strains,8.86%）,E-T-S（H）and E-T-C（5 strains each,6.33%）.（5）23 strains containing bla TEM-1 resistance gene were detected,the detection rate was 5.85%（23/393）,accounting for 38.98%of 59 strains of Enterobacteriaceae.No bla CTX-M,bla SHVwere detected.Among the 23 Enterobacteriaceae bacteria carrying bla TEMresistance genes,11 strains of Pantoea agglomerans（47.82%）,2 strains of Escherichia coli（8.69%）,and 1 strains of Klebsiella pneumoniae（4.34%）were detected.The resistance rate to ampicillin-sulbactam,tetracycline,cefoxitin and imipenem（allβ-lactam antibiotics）of Enterobacteriaceae bacteria which carry bla TEMresistance gene is higher than that of non-carrying bla TEM.（6）29 strains containing tet M gene were detected with the detection rate of 7.38%（29/393）,accounting for 36.71%of 79 strains of Enterococcus bacteria,and 67.44%of 43 strains of tetracycline-resistant strains.No van A,van B,tet K,tet A resistance genes was detected.Among 29 strains of Enterococcus bacteria which carry the tet M resistance gene,12 strains（41.38%）of Enterococcus faecium,9 strains（31.03%）of Enterococcus faecalis,and 4 strains（13.79%）of Enterococcus enterococcus were detected.The resistance rate to erythromycin,norfloxacin,ciprofloxacin,tetracycline,and streptomycin（high concentration）of Enterococcus bacteria which carry the tet M resistance gene is higher than that of the strains not carrying the tet M resistance gene.Conclusion（1）In 2019,the detection rate of Enterobacteriaceae bacteria from the feces of migratory birds in Nansha Wetland Park,Guangzhou City was low.A total of 12species of Enterobacteriaceae bacteria were detected,and the main dominant bacteria was Pantoea agglomerans.Only 3 to 4 strains of Escherichia coli and Klebsiella pneumoniae were detected.（2）The main dominant bacteria of Enterococcus faecalis from the feces of migratory birds are Enterococcus faecium and Enterococcus faecalis,and other enterococci such as Enterococcus lead flavus,Enterococcus enterococcus,Enterococcus gallinarum,and Enterococcus longis have been detected,suggesting the fecal bacteria of migratory birds in Guangzhou The types are complex and diverse.（3）Enterobacteriaceae bacteria from the feces of migratory birds in Guangzhou are mainly resistant to cefazolin,sulfisoxazole and ampicillin.The main resistance spectrum is G,G-S-Q,G-S,suggesting that Enterobacteriaceae bacteria are mainly resistant toβ-lactamase inhibitor antibiotics.（4）This article studied the detection of ESBLs resistance genes in Enterobacteriaceae bacteria from the feces of migratory birds in Guangzhou,and found that only bla TEM-1resistance genes were detected,suggesting that the main ESBLs resistance genes carried by migratory birds in Guangzhou are bla TEM-1.（5）Enterococcus bacteria from the feces of migratory birds in Guangzhou are mainly resistant to tetracycline and erythromycin.The main resistance spectrum is T,E-T,E-T-S（H）and E-T-C.In this study,only tet M was detected for Enterococcus bacteria in migratory birds,and no other common tetracycline resistance genes were detected,suggesting that the tetracycline-resistant Enterococcus bacteria in migratory birds mainly carry tet M.（6）7 strains of CRE were detected,of which 1 strain was CRKP.The detection rate of VRE was high,but van A and van B resistance genes were not found,indicating the existence of other vancomycin resistance-determining genes.It is suggested that migratory birds in Guangzhou are at risk of spreading CRE and VRE,and may play an important role in storing and spreading CRE and VRE. |
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