Comparison of PCR and Conventional Cultural Method for Detection of Salmonella from Poultry Blood and Faeces

摘要

The aim of the study was to compare Polymerase Chain Reaction (PGR) and conventional method for detection of Salmonella from field poultry samples (n = 510, poultry blood and faeces 255 each). The prevalence rate of Salmonella in chicken was found tobe 5.09% using conventional method and 5.88% by PCR assay. Serotyping of 26 Salmonella isolates revealed 57.69% Salmonella Typhimurium, 19.23% rough type, 15.38% Salmonella Enteritidis and 7.69% untypable. Among Salmonella Typhimurium isolates, 73.33% were from poultry blood and 26.66% from faeces samples. All isolates belonging to Typhimurium and Enteritidis serotypes were confirmed by PCR targeting of Salmonella Typhimurium (typfi) and Salmonella Enteritidis (enl) specific genes. However, 4 isolates found to be rough type also turned out to be positive for ent gene. The PCR employed for detection of Salmonella was found 100% sensitive for poultry blood but its sensitivity was very less (77.77%) for faeces samples as compared with culture method. However, PCR was 100% specific with regard to faeces samples. The specificity from blood samples was 97.89% by PCR. The positive predictive values of PCR from blood and faecal samples were 77.27 and 100% with a concordance of 98.03 and 99.21%, respectively.The negative predictive values from blood and faecal samples were 100 and 99.19%. The study demonstrated usefulness of genus specific PCR for detection of Salmonella in poultry clinical samples. Owing to its robustness and rapidity it can be used for wide epidemiological studies. Serotype specific PCR detection of Typhimurium and Enteritidis serotypes has added advantage in identifying them even where there is loss of O antigen.