TDK conference 2016

Actinobacillus pleuropneumoniae is known over the world as the etiologic agent of porcine pleuropneumonia. This bacterial pathogen affects only swine and induces acute hemorrhagic-necrotic pneumonia and fibrinous pleuritis with consecutive death, particularly in the terminal phase of fattening. The chronic or subclinical appearance of the disease is also responsible for significant economic losses. In its subclinical presence the A. pleuropneumoniae colonizes the pharyngeal tonsils of carrier individuals without any clinical signs of infection and may be unnoticed.

The ApxIV toxin out of the four different toxins produced by the A. pleuropneumoniae is specific, therefore the apxIV toxin gene is present only in this bacterium. The polymerase chain reaction (PCR) molecular biological method based on the detection of apxIV toxin gene is a reliable indicator of herd infection with this pathogen. Isolation on selective media is also a valuable diagnostic technique then evaluation of the biochemical features, antibiotic resistance and serotyping the strains is possible.

The Actinobacillus pleuropneumoniae has no human health risks, it infects only swine. The wild boar (Sus scrofa) is also susceptive to the disease and occurs as its potential reservoir, though no clinical signs of A. pleuropneumoniae infection in this species have been reported yet. In our study out of the 68 tonsils from feral swine tested with PCR for the presence of A. pleuropneumoniae, 10 samples appeared to be positive. This result shows that the native feral swine population in Hungary is infected with Actinobacillus pleuropneumoniae, as previously has been already reported in Germany, Slovenia, Greece and Canada.

During our research we focused on the development of a new, practicable selective medium and used an other selective medium which was described earlier. Furthermore, we managed to grow and isolate a NAD-dependent A. pleuropneumoniae strain originating from feral swine on a selective medium described in a study and identified it as serotype 12 using indirect hemagglutination test. We determined the minimum inhibitory concentrations of 15 antibiotics in case of this individual strain. It proved to be susceptible to ampicillin, amoxicillin/clavulanate, amoxicillin, enrofloxacin, tiamulin, doxycycline, chloramphenicol and florphenicol. The isolate shows intermediate resistance to oxytetracycline, resistance to penicillin, gentamicin, spectinomycin, cefoperazone, tulathromycin and tilmicosin.