Analysis Of Bacterial Factors Affecting Hatching Rate Of Healthy Broilers Insouthern Hebei Province

During the embryo and the fresh shelling chickens have weak resistance and are susceptible to attack of pathogenic microorganisms,leading to embryonic disease or death,decreased hatchability,and increased weak chick rate,which have an impact on the economic benefits of hatcheries or farms.Therefore,it is important to investigate and analyze the main pathogens of the fresh-shelling chicks and to screen effective therapeutic drugs,which is of great significance for the improvement of the rate of health and the prevention and control of embryonic diseases in chicks.In order to investigate the main pathogens in diseased or weak broiler chicks,118fresh-shelling diseased and weak parental broiler chicks were collected for pathological observation and bacterial isolation from their livers.These isolated bacteria were identified by the colonial morphology observation and 16S rDNA sequencing.The results showed that the diseased and weak broiler chicks had some unnormal symptoms such as larger abdominal circumference,malabsorptive yolk,and khaki liver full of cavitation under the microscope.58 isolates belonging to 11 species were isolated and identified and the isolation rate was 49.15%（58/118）.Among them,the isolation rate of the E.coli was 19.49%（23/118）,the Enterococcus faecalis was 16.10%（19/118）,the Shigella was 2.54%（3/118）,the Enterobacter cloacae was 2.54%（3/118）,the Klebsiella pneumoniae was 2.54%（3/118）,the Proteus mirabilis was 1.69%（2/118）,the Pseudomonas was 0.85%（1/118）,the Acinetobacter was 0.85%（1/118）,the Kocuria was0.85%（1/118）,the Salmonella enterica was 0.85%（1/118）,and the Naxibacter was0.85%（1/118）.These results suggest that fresh-shelling diseased and weak broiler chicks carried many kinds of bacteria among which Escherichia coli and Enterococcus faecalis were more dominant.Drug resistance of 19 isolated Enterococcus faecalis was analyzed.The results of KB paper susceptibility test showed that the resistance rate of the isolates to lincomycin（LIN）,ampicillin（AM）,cefotaxime（CTX）and polymyxin（CL）was 100%,the resistance rate to mycin（S）and tetracycline（TE）was 94.74%,the resistance rate to doxycycline（DO）was 84.21%,the resistance rate to spectinomycin（SPT）and azithromycin（AZM）was 73.68%,the resistance rate to gentamicin（CN）,neomycin（N）and erythromycin（E）was 68.42%,the resistance rate to kanamycin（K）was 63.16%,the resistance rate to ofloxacin（OFX）was 52.63%,the resistance rate to enrofloxacin（ENR）was 47.37%,the resistance rate to levofloxacin（LEV）was 42.11%,the resistance rate to penicillin（P）was 36.84%,and the resistance rate to vancomycin（VA）was 5.26%.The minimum inhibitory concentration（MIC）of the isolates was further determined.The results showed that the MIC₅₀0 of tetracycline was greater than 256μg/mL,the MIC₉₀0 was greater than 256μg/mL,and the drug resistance rate was 94.74%.The MIC₅₀0 of streptomycin was greater than 2048μg/mL,and the MIC₉₀0 was greater than 2048μg/mL,and the drug resistance rate was 84.21%.The MIC₅₀0 of erythromycin was greater than 256μg/mL,the MIC₉₀0 was greater than 256μg/mL,and the drug resistance rate was 84.21%.The MIC₅₀0 of ofloxacin was 64μg/mL,the MIC₉₀0 was greater than 128μg/mL,and the rate was 52.36%.The MIC₅₀0 of vancomycin was 2μg/mL,the MIC₉₀0 was 4μg/mL,and the drug resistance rate was 0%.The results indicated that the isolated Enterococcus faecalis has multiple drug resistance and multi-drug resistance,suggesting that sensitive drugs should be selected to treat Enterococcus faecalis infection.The drug resistance genes were detected in 19 isolated Enterococcus faecalis.The results showed that the gene AAC（6ˊ）-APH（2"）was detected in 11 isolates,the detection rate was 57.89%,and the coincidence rate with the drug resistant phenotype was 84.62%.The gene APH（3ˊ）-III was detected in 11 isolates,the detection rate was57.89%,and the coincidence rate with drug-resistant phenotype was 91.67%.The gene ANT（6ˊ）-I was detected in 10 isolates,the detection rate was 52.63%,and the coincidence rate with the drug resistance phenotype was 55.56%.The gene ermB was detected in 13 isolates,the detection rate was 68.42%,and the rate of resistance to the drug-resistant phenotype was 100%.The gene tetM was detected in 8 isolates,the detection rate was 94.74%,and the coincidence rate with the resistant phenotype was100%.Gene TEM,mefA,vanA,vanB were not detected.The results showed that the drug resistance gene of Enterococcus faecalis was basically consistent with its drug resistance,and drug resistance is related to carrying drug resistance genes.