Estimation of the sensitivity of four sampling methods for detection in live pigs using a Bayesian approach

Christelle Fablet (1) , Corinne Marois (1) , Marylène Kobisch (1) , François Madec (1) , N. Rose (1)

1 Laboratoire de Ploufragan - Plouzané

Four sampling techniques for detection, namely nasal swabbing, oral-pharyngeal brushing, tracheo-bronchial swabbing and tracheo-bronchial washing, were compared in naturally infected live pigs. In addition, a quantitative real-time PCR assay for quantification was validated with the same samples. 60 finishing pigs were randomly selected from a batch of contemporary pigs on a farm chronically affected by respiratory disorders. Each pig was submitted to nasal swabbing, oral-pharyngeal brushing, tracheo-bronchial swabbing and tracheo-bronchial washing. Nested-PCR and Real-Time PCR assays were performed on all samples. A Bayesian approach was used to analyze the nested-PCR results of the four sampling methods (. positive or negative) to estimate the sensitivity and specificity of each method. was detected by nested-PCR in at least one sample from 70% of the pigs. The most sensitive sampling methods for detecting in live naturally-infected pigs were tracheo-bronchial swabbing and tracheo-bronchial washing, as compared to oral-pharyngeal brushing and nasal swabbing. Swabbing the nasal cavities appeared to be the least sensitive method. Significantly higher amounts of DNA were found at the sites of tracheo-bronchial sampling than in the nasal cavities or at the oral-pharyngeal site (p<0.001). There was no difference between the tracheo-bronchial washing and the tracheo-bronchial swabbing results (p>0.05). Our study indicated that tracheo-bronchial swabbing associated with Real-Time PCR could be an accurate diagnostic tool for assessing infection dynamics in pig herds.

Mots clés: sampling methods; real time PCR; bayesian analysis

Domaines: Sciences du Vivant [q-bio]

Christelle Fablet, Corinne Marois, Marylène Kobisch, François Madec, N. Rose. Estimation of the sensitivity of four sampling methods for detection in live pigs using a Bayesian approach. Veterinary Microbiology, 2009, 143 (2-4), pp.238. ⟨10.1016/j.vetmic.2009.12.001⟩. ⟨hal-00514961⟩