Histopathological Observation of Colibacillosis in Laying Hens

[Objective] This study aimed to investigate the histopathological changes of hens with colibacillosis.[Method] Epidemiological investigation,clinical symptoms observation,pathological autopsy,laboratory diagnosis and paraffin-embedded tissue section were performed to diagnose the laying hens from a farm in Changli County,affected by a disease similar to pericarditis and perihepatitis in clinical symptoms.[Result] The pathogen isolated from those hens was E.coli.The histopathological changes of the diseased hens included myocardial cell degeneration and inflammatory cell infiltration in heart,fibrotic perihepatitis,necrotic hepatitis in liver,decreased lymphoid cells and inflammatory cell infiltration in spleen,lung congestion,lung room full of erythrocytes,hyaline degeneration in glomerular capillary and small intestinal epithelial cell shedding.[Conclusion] This study will provide scientific basis for the diagnosis and control of colibacillosis in poultry.

Diagnosis of Colibacillosis in Foxes

An epidemic occurred in a fox farm of Changli County in April, 2015. The clinical symptoms in ill foxes included depression, poor appetite or appetite loss,rough, disorder and dull hair, standing inability, trembling, sunken eyes, decreased skin elasticity, dehydration and loose stools around the anus. When the abdomens of ill foxes were pressed, white or yellow manure flew out from the anuses, and some of the manures contained mucus or blood. The pathological changes included liver enlargement with necrotic lesions, spleen enlargement, lung hemorrhage, kidney enlargement with bleeding spots, thymus hemorrhage and intestinal catarrhal inflammation. The epidemic was finally identified as colibacillosis through clinical symptoms observation, pathological anatomy, biochemical tests and 16 SrRNA amplification.

Antimicrobial Drug Resistance Pattern of <i>Escherichia coli</i>Isolated from Chickens Farms with Colibacillosis Infection

Colibacillosis refers to any localized or systemic infection caused entirely or partly by avian pathogenic Escherichia coli (APEC). Colibacillosis in mammals is most often a primary enteric or urinary tract disease, whereas colibacillosis in poultry is typically a localized or systemic disease occurring secondarily when host defenses have been impaired or overwhelmed by virulent E. coli strains. The purpose of this study was to investigate the antimicrobial drug resistance pattern of Escherichia coli isolated from broiler chickens farms with colibacillosis infection. Dead birds from commercial broiler chicken farms showing signs of colibacillosis were necropsied and swab samples were collected from internal organs and blood aseptically for the isolation of Escherichia coli. Pure colonies of the bacteria were isolated on solid media and the isolates were identified as E. coli based on morphological and biochemical characteristics. For determination of susceptibility to antibacterial agents, the disc diffusion method on Muller-Hinton agar was used. The following antimicrobial agents were tested: gentamycin, oxytetracyline, colistin, ciprofloxacin, doxycycline, nalidixic acid, co-trimoxazole (trimethoprim-sulfamethoxazole), norefloxacin, lincospectin and cefuroxime. The drug resistance patterns of the organisms were determined as a percentage and reported at three levels: susceptible, intermediate and resistant. All the isolates of Escherichia coli showed resistance to several antibiotics and a pattern of multiple drug resistance was observed. The highest rate of resistance was observed against nalidixic acid (100%) and the least rate of resistance was observed against gentamycin (17%). According to the results of this research care must be taken to avoid secondary infection (colibacillosis) in chicken farms and also avoid in careless antimicrobial consumption in food animals including chickens.

Diagnosis and Prevention of Colibacillosis in Chickens

The characteristics of chicken colibacillosis are introduced from the aspects of pathogen,epidemiology,clinical symptoms and necropsy,and clinical comprehensive diagnosis and laboratory diagnosis methods are given.The disease is distinguished from diseases with similar symptoms such as chicken chlamydia,chicken streptococcus,chicken necrotic enteritis,broiler ascites syndrome and chicken paratyphoid infections.Eventually,the preventive and therapeutic measures against the disease are put forward.

Screening and Efficacy Observation of Traditional Chinese Medicine Against Chicken Pathogenic Escherichia coli

[ Objective] The aim of this study was to lay a foundation for obtaining effective traditional Chinese medicine preparations controlling chicken colibacillosis. [ Method] With the western medicine Lomeflbxacin Hydrochloride and Sodium Chloride Injection as the control, drug sensitivity tests of 15 single traditional Chinese herbs and seven self-made Chinese herbal compounds were conducted. Subsequently, the single traditional Chinese herbs presenting good in vitro antibacterial effects against Escherichia coli and all the seven compounds were given to the chicks artificially infected with E. coil to observe their efficacies. [ Result] The results of drug sensitivity tests showed that all the 15 traditional Chinese herbs had certain antibacterial effect against E. coli, among which aloe, pomegranate rind and radix sanguisorbae were the best. Compound 1, 2 and 5 had good antibacterial effects in vitro. By in vivo test, traditional Chinese medicines showed superior efficacies on infected chicks than western medicine, and compound 1 and 2 performed well. [ConclusiOn] Traditional Chinese medicine preparations are good at controlling Chicken colibacillosis, but their bacteriostasis mechanism in vivo was different with that in vitro.

Drug Sensitivity Test and Regression Verification of Escherichia coli from Rex Rabbit

[ Objectives] The paper aimed to select drugs reasonably for treatment of rex rabbit colibacillosis, and to isolate the pathogenicity of Escherichia coll. [ Methods ] Pathogen isolation, drug sensitivity test and pathogen regression test were performed with rex rabbits killed by E. coli in clinic. [ Results] The isolate was E. coli 0-23, susceptible to amikacin and cefotaxime sodium; when the challenge dose was 1.0 mL/rabbit （about one billion E. coli）, the test animal would discharge mucous feces. [ Conclusions] The results provided model support for clinical medicine selection against rex rabbit colibacillosis.