EVALUATION OF A PCR FOR DETECTION OF ACTINOBACILLUS-PLEUROPNEUMONIAE IN MIXED BACTERIAL CULTURES FROM TONSILS

A PCR for the detection of Actinobacillus pleuropneumoniae was evaluat ed. All of 102 field isolates of A. pleuropneumoniae reacted in the PC R by amplification of a 985 bp product. No PCR amplification product w as observed when examining strains of A. ureae, A. capsulatus, A. homi nis, A. equuli, A. rossii, A. suis, Escherichia coli, Bordetella bronc hiseptica, Streptococcus suis, Pasteurella haemolytica, Pasteurella mu ltocida, Haemophilus parasuis, Haemophilus taxon Minor group, Haemophi lus taxon D/E and Haemophilus taxon F. Amplification of a 985 bp produ ct was, however, observed when testing strains of A. lignieresii. The lower detection limit of the PCR test was 10(3) A. pleuropneumoniae CF U/PCR test tube and was not affected by addition of 10(6) E. coli CFU/ PCR test tube. Mixed bacterial cultures from tonsils of 101 pigs from 9 different herds were tested by culture and by PCR using four differe nt bacteriological media. While 65% reacted positive; in the PCR only 23% were positive by culture, thereby suggesting a superior sensitivit y of the PCR test to that of culture. The use of selective media, larg e inoculum and incubation for 48 h gave the highest number of positive PCR reactions from mixed bacterial cultures. Tonsil cultures from 50 pigs from an A. pleuropneumoniae-negative herd did not react in the PC R. The results show that PCR on mixed bacterial cultures from tonsils may be a highly sensitive method for the detection of A. pleuropneumon iae in pig herds.