Etiopathology of cellulitis in broilers from Nagpur region of central India

Abstract

Avian cellulitis, bacterial disease of broilers caused by avian pathogenic Escherichia coli (APEC) contributes substantial economic losses to the broiler industry due to condemnations of carcass during post- mortem examination at slaughter house. The present study was conducted to study etiopathology of cellulitis cases and to characterize the E. coli isolates recovered from affected broilers across Nagpur region of central India. Total 9 broiler farms affected with cellulitis were screened and post-mortem examination was conducted on 28 broiler carcasses. The post mortem examination was carried at Department of Veterinary Pathology, Nagpur Veterinary College, Nagpur. Grossly the birds affected with cellulitis showed thickened and yellowish discoloured skin on inner aspect of thigh muscle, wings, breast, keel bone area, back and flank region. Fibrinopurulent exudate in subcutaneous tissue was observed. Microscopically, hyperkeratosis, thickened dermis, heavy infiltration of mononuclear cells and heterophils along with fibrinocaseous exudates and necrosis of the skin was observed. Samples from the affected portion of birds were cultured on Brain Heart Infusion (BHI) agar and Eosin Methylene Blue (EMB) agar media and overnight incubated at 37 °C. The result revealed that most of the samples showed growth of E.coli (93%), mixed with other bacterial isolates mainly Staphylococcus, Enterococcus and Proteus spp etc. Confirmation of the bacterial colonies was done by MALDI- TOF MS analysis. Antibiotic sensitivity test showed maximum sensitivity towards colistin sulphate. Later the virulence profiling of these E. coli isolates was done by PCR detection of cvi and tsh genes. Genotyping of the samples was done by ERIC-PCR; comparison of the cellulitis E.coli samples was done with the other non- cellulitis E. coli of poultry, dog, cow and buffalo. This study demonstrated the E. coli is major pathogen causing cellulitis in Nagpur region, the isolates are sensitive to colistin sulphate and these isolates are typed similar on ERIC PCR. Key words: Cellulitis, Escherichia coli, ERIC-PCR and MALDI-TOF MS analysis. Abbreviations: BHI= Brain Heart Infusion agar, EMB= Eosin Methylene Blue agar, MALDI-TOF MS= Matrix-Assisted Laser Desorption/Ionization-Time of Flight Mass Spectrometry, ERIC-PCR=Enterobacterial Repetitive Intergenic Consensus-Polymerase Chain Reaction, AST= Antibiotic Sensitivity Test, PCR= Polymerase Chain Reaction, cvi= colicin V immunity protein, tsh= temperature-sensitive hemagglutinin.