Diagnosis and Treatment of a Disease Caused by Mixed lnfection of Escherichia coli and Arthrinium saccharicola in Bamboo Rats

Shimin LUO，Guangzhong HUANG，Wuzhen SU，Hui HU

Huaihua Vocational and Technical College，Huaihua 418000，China

Diagnosis and Treatment of a Disease Caused by Mixed lnfection of Escherichia coli and Arthrinium saccharicola in Bamboo Rats

Shimin LUO，Guangzhong HUANG，Wuzhen SU，Hui HU*

Huaihua Vocational and Technical College，Huaihua 418000，China

The feeding amount of bamboo rats in Southern China is increased year by year.Under condition of captive breeding，the occurrence of diseases has also become more and more frequent in bamboo rats.In this paper，the results of morphological and biochemical studies showed that the cultural and biochemical characteristics ofisolated strains are basically the same，and they allhave strong pathogenicities to bamboo rats.The disease was diagnosed to be caused by the mixed infection ofEscherichia coliandArthrinium saccharicola，and it was controlled by corresponding measures.

Bamboo rat；Mixed infection；Diagnosis；Prevention

Bamboo rats belong to Mammalia，Rodentia，Rhizomyidae and Rhizomys.Due to their liking eating bamboo，they are called as bamboo rats.The body length of bamboo rats is generally about 30-40 cm，and of some individual species can be up to 45 cm.Bamboo rats favor eating underground stems of bamboo，bamboo shoots and other plants.They have one baby each year.Bamboo rats have high-quality long and dense fur. Their meat is tender，and can be eaten.Their fat is called as bamboo rat oil，can be used for external application.

Currently，the breeding amount of bamboo rats is increased year by year，and the demand is also increased year by year.In Shenzhen，Zhuhai，Hong Kong，Guangzhou，Haikou，Shanghai and other coastal cities，the sales of bamboo rat products is always good，and the price always shows strong momentum.The roasted bamboo rats have higher profits.According to incomplete statistics，Sichuan，Yunnan，Guizhou，Hunan，Jiangxi，Guangxi，Guangdong，Hainan，Hong Kong，Fujian and Shanghai consume more than 100 000 bamboo rats.However，the current production capacity of bamboo rats cannot meet the market demand［1-4］.In recent two years，the breeding of bamboo rats has begun to heat up gradually，which requires a large number of young bamboo rats.However，due to the effects of climate，feed and other factors，the disease caused by mixed infection of Escherichia coli and Arthrinium saccharicola occurs frequently in bamboo rats.In particular，in some farms with relatively backward management and prevention technology，the incidence and mortality of the disease are higher，and the disease is even endemic.On February 29，2015，from total 700 diseased bamboo rats（dominanted by young and female），three bamboo rats infected with Escherichia coli and Arthrinium saccharicola were selected，and they were studied comprehensively from perspectives of morphology and microbiology.In addition，some effective prevention and control measures were carried out.This study will provide some reference for future studies on mixed infection of Escherichia coli and Arthrinium saccharicola in bamboo rats.

lncidence

Total 1 200 bamboo rats at different ages were bred in a farm in Huaihua City.They were fed with moldy sugarcane stumps in varying degrees. The moldy sugarcane stumps turned soft，and the color of their fleshes with mild moldy smell were darker than normal（light brown red）.The disease was expanded gradually among the bamboo ratssince February18，2015. Some diseased bamboo rats were depressed and stood transfixed with decreased feed intake and diarrhea.On day 5 since the first incidence，the clinical symptoms aggravated and some bamboo rats，especially female rats，even died.The number of dead rats was increased from 5 a day to 20 a day.The diseased bamboo rats were fed continuously with amoxicillin and enrofloxacin for seven days，but the control effect was not ideal.Total 260 bamboo rats died.

Clinical Symptoms and Autopsy Changes

The clinical observation found that the bamboo rats in the farm had uneven sizes，and the incidence rate was about 58%.The diseased rats stood transfixed and were depressed with difficulty breathing，decreased or even abandoned appetite and greatly increased water intake.The diseased rats all had a diarrhea，and their feces had a fishy smell.

Total three bamboo rats （one dead and two live）with uneven sizes were dissected.The dead rat was relatively thin，and its skin was tight and difficult to be peeled；the leg skin was dry；there was a small amount of feces around the anus；the liver was bleeding；two third of the intestine was obviously flatulent，and intussusception appeared in the remaining part；there was a small number of hemorrhages in the intestine；there was white stool in the rectum with obvious peritonitis；the spleen was swelling and bleeding with infarctions；the kidney，with white nodules，was 3-4 times larger than the normal，and its section was juicy；the bilateral lungs were pale purple and edematous，and in its section，there were rice grain-sized yellow-white nodules，which were speculated to be fungal colonies（Fig.1）.Therefore，after a comprehensive analysis on the dead case，the disease was speculated to be caused by the mixed infection of Escherichia coli and Arthrinium saccharicola.

Pathogen ldentification

The heart blood，pericardial fluid and tissue fluids of liver and kidney of the selected rats were inoculated in media and incubated.On conventional agar slant，the bacterial colonies，with diameter of 1-2 mm，were round，swell， smooth， moist， pale and translucent.On MacConkey agar plate，the bacterial colonies were red，and their size was the same with that of colonies in conventional agar.The colonies were then smeared，stained and observed.Under a microscope，gram-negative short bacilli with rounded ends were shown［5］，and they were not identified as Salmonella.

The used sugarcane was examined under a microscope.A large number of fungal hyphae were found in cane cells.After the incubation by potato culture medium，Arthrinium saccharicola strains were isolated［2］.

The isolated Arthrinium saccharicola strains can ferment glucose，maltose，lactose and sucrose，and they produce acids and gases.In the M.R. test and p-dimethyl aminobenzaldehyde test，the results were positive，while in the VP test and citrate utilization test，the results were negative［3］.

The isolated strains are highly sensitive to florfenicol，doxycycline and cefradine，and are moderately sensitive to compound ciprofloxacin，but they are insensitive to other drugs.

Control Measures

The farming house and stools were sprayed with Xiaoduwei for disinfection.The diseased bamboo rats were injected with cefradine according to conventional amount for three consecutive days.At the same time，florfenicol powder was added to feed and fed to lactating female rats.After 3-4 d of treatment，the diseased rats returned to normal.

The high-efficiency Tuomeijing was mixed with the feed （1:1 000），and fed to the bamboo rats for five consecutive days.

Along with the treatment by drugs above，cod liver oil and electrolytic vitamins were dissolved in water and fed to bamboo rats for five consecutive days.

The mortality of bamboo rats began to be reduced on day 4 since the application of drugs；on day 7，the number of dead rats was reduced to two，and the appetite of bamboo rats was recovered.So，probiotics，such as Yiyangjia，were recommended to be added in feed to regulate the intestinal flora，increase beneficialbacteria colonies and improve the intestinal environment.The probiotics were fed to bamboo rats for seven consecutive days.

Conclusions

The disease in bamboo rats is caused by the mixed infection of Escherichia coli and Arthrinium saccharicola.During the treatment，the source of infection must be removed. Therefore，the high-quality fresh feed，instead of moldy feed，should be feed to bamboo rats.The high-efficiency Tuomeijing can be added to feed during the storage.Since immature sugarcane is easy to mildew，sugarcane should be better harvested after the maturity.To prevent mildew，sugarcane cannot be stored for too long time.Moreover，during the storage，the sugarcane should be inspected regularly.

The mycotoxins in bamboo rats can be cleared by physical adsorption，chemical detoxification and biodegradation［6-10］.Colibacillosis is a common disease in farms，and its occurrence is closely related to environment，temperature，feed，water and other factors. Forthe treatmentofcolibacillosis，sensitive drugs should be adopted，but drug abuse must be avoided.Moreover，the dosage of drug against colibacillosis must be sufficient，because inadequate dosage has no satisfactory curative effect［6-8］.In addition，to prevent and control this disease，disinfection should be enhanced，farming conditions should be improved，and antibiotic therapy and immunization can be combined.During the treatment of colibacillosis，high-dosage electrolytic vi-tamins should be better feed to bamboo rats to facilitate the clearance of colitoxin and to improve body’s immunity.The cod liver oil can promote the recovery of damaged intestinal epithelial cells.Probiotics has a very considerable effect in treatment of colibacillosis，especially when they are added to the feed in the recovery process.They play an important role in reconditioning intestinal flora［9-10］.

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Responsible editor：Tingting XU

Responsible proofreader：Xiaoyan WU

竹鼠大肠杆菌病与霉菌病混感的诊治

罗世民，黄光中，苏五珍，胡辉*（怀化职业技术学院，湖南怀化418000）

南方竹鼠饲养量在逐年增多，竹鼠在圈养状态下疾病日趋增多。该文通过形态观察、生化试验，表明分离菌其培养特性与生化特性基本一致，对竹鼠具有很强致病力。诊断为大肠杆菌病与霉菌病混感并采取相应的防治措施。

竹鼠；大肠杆菌病与霉菌病混感；诊断；防治

罗世民（1980-），男，湖南新化人，讲师，硕士，主要从事动物医学教学及技术服务，E-mail：124328975@qq.com。*通讯作者。

2015-05-28

*Corresponding author.E-mail:huhui5909@126.com

Received:May 28，2015 Accepted:December 17，2015

修回日期 2015-12-17