Evaluation of survival of Actinobacillus pleuropneumoniae and Haemophilus parasuis in four liquid media and two swab specimen transport systems.
OBJECTIVE
To determine duration and rates of recovery of Actinobacillus pleuropneumoniae and Haemophilus parasuis from 4 liquid media and 2 swab specimen transport systems and compare findings with those of Escherichia coli.


METHODS
One strain each of A pleuropneumoniae (biovar 1, serotype 1), H parasuis (serovar 5), and E coli (serotype O149:K91:H19).


METHODS
Strains were incubated in brain heart infusion broth supplemented with horse serum and other nutrients or in horse serum alone, with and without nicotinamide-adenine dinucleotide in both instances, for 150 days at 4 degrees C or room temperature (21 degrees C). Similarly, strains were tested in Stuart and Amies transport systems after storage at room temperature for 8 days.


RESULTS
Colony counts greater than those of the initial inoculum were observed after incubation in horse serum for A pleuropneumoniae but not for H parasuis. Overall, incubation at 4 degrees C in the 4 liquid media resulted in longer recovery duration and higher rates than at room temperature. Culture of H parasuis resulted in lower recovery rates and shorter durations of recovery than culture of A pleuropneumoniae, except for culture in horse serum. Haemophilus parasuis survived longer than A pleuropneumoniae in the transport systems, and all organisms survived longer in the Amies system.


CONCLUSIONS
Survival of A pleuropneumoniae and H parasuis indicated that horse serum prolongs survivability, which may result in exposure of more animals during a prolonged period. The Amies system might be a good choice for collection of clinical samples from animals, especially for recovery of H parasuis.
D016977:Actinobacillus pleuropneumoniae / Q000254:growth & development* / Q000302:isolation & purification; D000818:Animals; D015169:Colony Count, Microbial / Q000662:veterinary; D003470:Culture Media; D004926:Escherichia coli / Q000254:growth & development; D006190:Haemophilus / Q000254:growth & development* / Q000302:isolation & purification; D006736:Horses; D013048:Specimen Handling / Q000379:methods
D003470:Culture Media