Isolation And Identification Of A Strain Of Neisseria Macacae Derived From Saimiri Sciureus And Its Biological Characteristics

On August 20,2017,the death of a squirrel monkey died in a zoo in Anhui province.The clinical symptoms were mainly due to loss of appetite and depression,and died within a short period of time.The necropsy showed spotting bleeding on the surface of the liver and hyperplasia of the surrounding tissue.Widened interstitial lung with diffuse bleeding.There is a lot of white foam in the mouth,nose and trachea.In order to diagnose the cause of the disease,the pathogens were isolated and identified by methods such as isolation and culture,morphological observation,growth characteristics,and molecular biological detection.A gram-negative cocci was isolated from the liver of dead squirrel monkeys and grew well on medium containing serum,showing yellow,dry,harder colonies.The size of the bacteria is between0.5?m and 0.6?m,which is an irregular spherical shape with protrusions on the surface.Maltose,fructose,sucrose,lactose and glucose fermentation were positive,oxidase test was positive and nitrate reduction was negative.Based on the 16S rRNA sequence alignment,the isolate was initially identified as a strain of Neisseria,with a homology of 99%and the highest affinity with Neisseria macacae 6250,designated as NS-9 strain.To understand the biological characteristics of the isolates,the culture characteristics and drug susceptibility were studied.The logarithmic phase of the isolate is between 6 and 12 h.Comparison of acidic conditions with basic conditions found that the survival rate is higher under acidic conditions.It is sensitive to aminoglycosides,quinolones,and?-lactams and is resistant to enrofloxacin,cotrimoxazole,lincomycin,and penicillin.In order to explore the pathogenicity of the isolates,two virulence genes related to the iron-supply system were detected in the isolates,the TonB siderophore-dependent receptor and the ferric iron uptake/transport regulator.The number of challenged mice in the abdominal cavity of the animal test was 1.04×10¹⁴CFU/body,followed by clinical manifestations of loss of appetite and depression,but not death.Pathological observations revealed bleeding and congestion in the heart,liver,lungs,spleen,and kidneys.Some necrosis and proliferation of liver cells,alveolar collapse,local necrosis of alveolar epithelial cells,necrosis of renal tubular epithelial cells,accumulation of a large number of multinucleated giant cells in the spleen.In summary,this study isolated a strain of Neisseria rhynchophylla from the liver of a squirrel monkey and was suspected to be a pathogen.The virulence of mice is weak.