| Staphylococus(Staphylococus)is a kind of gram-positive bacteria,most of which are spherical or oval in shape,with a diameter of about 0.5um ~ 1.5um.It does not require high nutritional environment,and belongs to facultative anaerobe.As a result,they tend to proliferate in the body,causing damage to the organism.Staphylococcus chromogenus belongs to coagulase negative staphylococcus.It has no flagella,and most strains do not have buds or capsules.It is an opportunistic pathogen.In addition to causing symptoms such as septicemia in pigs,avian arthritis and mastitis in dairy cows,Staphylococcus chromogenes can also cause diseases such as human mastitis and septicemia.Therefore,Staphylococcus chromogenic has an important public health status.Because of its toxin production and the increasing reports of animal isolates,it has become an important pathogen of clinical infection.In order to investigate the infection of Staphylococcus chromogenes in Aksu area,420 chicken tissue samples were collected from Aksu City,Kuqa City,Baicheng County and Xinhe County for bacteria isolation and culture.By observing the morphological and biochemical characteristics of the isolated bacteria,it was preliminarily identified as Staphylococcus chromogenes.78 strains of Staphylococcus chromogenes were identified by PCR.The separation rates of Aksu City,Kuqa City,Xinhe County and Baicheng County were 17.31 %,5.65 %,12.20 % and 33.33 %,respectively.Ten kinds of virulence genes were detected in 78 strains of Staphylococcus chromogenes.The results showed that four kinds of virulence genes were detected,namely sec,seg,ica D and Alt,with the detection rate of 21.79 %~35.90 %.The highest virulence gene was sec(35.90%).The lowest virulence gene was Alt(21.79 %).The detection rates of ica D gene and seg gene were32.05 % and 29.49 %,respectively.These results indicated that Staphylococcus chromogenes mainly carried sec and tsst-1 virulence genes in Aksu area.The results showed that the bacteria had certain pathogenicity to the chicks and could cause the death of the chicks after 24 h inoculation.Necropsy of the dead chicks showed liver enlargement,congestion and grayish white necrotic spots on the surface.The upper end of the right lung became fleshy,and the upper end of the left lung was covered by inflammatory secretions;No significant lesions were found elsewhere.The bacteria isolated from liver and other parts were identified by PCR as Staphylococcus chromogenes.78 strains of Staphylococcus chromogenes were detected,and the results showed that bla TEM,TEM,sul2,aac(6’)-Ib,aph(3’)-1a,Ant(6)-I,aac(6’)/aph(2 "),tet(A),tet M,erm B were detected.The detection rates were 44.87 %、43.59 %、61.54 %、20.51 %、34.62 %、10.26 %、26.92 %、37.18 %、15.38 %、16.67 %.The results of drug sensitivity test showed that 78 strains of Staphylococcus chromogenes had different degrees of resistance to 16 kinds of antibiotics,and the resistance rate was 5.13%-85.90%.The resistance rate to neomycin was the highest(85.90%).The drug resistance rate to penicillin,cotrimoxazole,doxycycline,neomycin,streptomycin and polymycin B was relatively high,ranging from 50 % to 80 %.The rate of resistance to the remaining 9 drugs was lower than 30 %.In conclusion,the infection rate of Staphylococcus chromogenes in chickens in Aksu area of Xinjiang is relatively low,ranging from 5.65%-33.33%.The isolates had drug resistance and pathogenicity.The results enriched the understanding of Staphylococcus chromogenes from chicken and provided reference for the treatment and prevention of infection caused by this bacterium in chicken farms. |
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