Prevalence of Bacterial Diseases of Commercial Poultry at Chittagong

Abstract

The aim of the present work was to determine the prevalence of bacterial diseases of commercial poultry in Chittagong region through a cross-sectional study. A ten months long study was conducted from August 2011 to May 2012. A questionnaire was used to record additional information, such as age and type of birds, litter type farm category, sex, pathological lesions present, sample collection site, etc. In total, 320 dead chickens were subjected to postmortem and organs (trachea, lungs, liver) along with swab (pus) samples were collected. First of all a tentative diagnosis was made on the basis of observation of clinical signs and postmortem lesions. Then all the postmortem samples were inoculated into nutrient broth followed by inoculation into specific media, such as EMB and mannitol salt agar to determine by their typical colony characterization as E. coli or staphylococcus. sp. respectively. They were further tested with Spot indole test and coagulase test for E.coli and Staphylococcus.sp respectively. Bacteriologically positive organisms were finally tested by PCR using previously published primer sets to detect a 16S rRNA gene specific for E.coli and 16S-23S rRNA-spacer gene for staphylococcus. sp. The bacterial agents isolated and identified from the samples were also investigated for their antibiotic resistance pattern. An attempt was also made to establish a relationship of this resistance pattern with other factors like season, production type and age. Out of the samples collected from 320 chickens 58% were found to be positive for bacterial growth. According to clinical signs and postmortem lesions 48.44% of the chickens were diagnosed tentatively as the case of Colibacillosis and 8% as the case of staphylococcosis. Using the method of confirmatory diagnosis (bacteriological culture and biochemical test) the rate of colibacillosis and staphylococcosis was found to be 48.44% and 8% respectively. The prevalence of E.coli in chickens was highest during autumn (74%) followed by winter (60%) and then summer (21%). Prevalence was higher in commercial broilers (55%) than in commercial layers (25%) and according to age group it was higher in ≤30 days age groups (56%) compared to adults (4%). Prevalence of colibacillosis was found highest (56%) in saw dust litter management system with the lowest (18%) being in rice husk management system. Staphylococcosis was found to occur in chickens at the rate of 22% during autumn and during winter the rate of occurrence of the disease was only 5%. In Culture sensitivity (CS) test the organisms under study were found 100% sensitive to cephradin (CH) and kanamycine (Kacin) but completely resistant to ampicillin, penicillin and ciprofloxacin. For E. coli cephalexin (86%) and doxycycline (69%) showed intermediate sensitivity but, amoxycilline and enrofloxacin showed 84.11% and 45.14% resistance respectively. For staphylococci cephalexin showed intermediate sensitivity (81%) but, doxycycline and amoxycillin showed 100% sensitivity. On the other hand colistin sulphate, enrofloxacin and neomycin showed 63%, 96.3% and 100 % resistance respectively. The extracted DNA was amplified by PCR using ECO-f and ECO-r primer targeting the E. coli 16S ribosomal RNA and a 585 bp amplicon was found after 1% agarose gel electrophoresis that confirmed the isolates to be E. coli.