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Bacterial respiratory diseases are responsible for considerable mortality, morbidity and economic losses in the swine industry. Actinobacillus pleuropneumoniae, the causative agent of porcine pleuropneumonia, is one of the most important disease agents, but its identification and surveillance can be impaired by the existence of many other related bacteria in normal swine microbiota. In this work, we have evaluated a BOX-A1R-based repetitive extragenic palindromic- PCR ( BOX- PCR) sequence characterised amplified region ( SCAR) marker for the specific identification of A. pleuropneumoniae and its use in a multiplex PCR to detect additionally Haemophilus parasuis and Pasteurella multocida, two other major respiratory pathogens of pigs that are members of the family Pasteurellaceae. PCRs based on the BOX- SCAR fragment developed were rapid, sensitive and differentiated A. pleuropneumoniae from all swine-related members of the Pasteurellaceae family tested. Single and multiplex BOX- SCAR fragment-based PCRs can be used to identify A. pleuropneumoniae from other bacterial swine pathogens and will be useful in surveillance and epidemiological studies. [ABSTRACT FROM AUTHOR]

We have identified a highly transformable strain of Actinobacillus pleuropneumoniae whose competence is regulated by the competence-activator Sxy as in other Pasteurellaceae. Other strains were poorly transformable or nontransformable. The genomes of two poorly transformable strains contain intact sets of competence genes. Moreover, we show that the low competence of one of these strains is not due to an inability to induce sxy expression or to a defect in Sxy function, suggesting that some other component of the competence system is defective. Although the A. pleuropneumoniae sxy gene has only 24% identity to its Haemophilus influenzae homologue, both genes fully complemented an H. influenzae sxy knockout, demonstrating that Sxy function is conserved throughout the Pasteurellaceae. [ABSTRACT FROM AUTHOR]

Abstract: We report the identification and nucleotide sequence analysis of a cryptic plasmid pMIDG2830 from the Gram-negative bacterium Neisseria flavescens. The largest open reading frame encodes a protein similar to the replication protein, RepA, found in pAB49 from Acinetobacter baumannii and pNI10 from Pseudomonas. Modified by the incorporation of a kanamycin resistance cassette, the plasmid can be stably maintained in Escherichia coli and Neisseria meningitidis, and can be used as a shuttle plasmid in meningococcal research. [Copyright &y& Elsevier]

We have investigated the use of a natural transformation protocol to introduce mutations into Actinobacillus pleuropneumoniae serotypes 1 and 5b. For both strains tested, we recovered 1 in 108 transformants during culture in rich medium, a result that was independent of the growth phase. This low frequency of transformation of A. pleuropneumoniae did not increase when bacteria were grown under conditions known to be optimal for induction of competence in Haemophilus influenzae. Using linearised plasmid DNA containing a kanamycin cassette inserted into the sodC gene of A. pleuropneumoniae serotype 1, we showed that natural transformation can be used as a simple method for introducing allele replacements into this bacterium, and can be used to transfer mutations from one serotype to another. [Copyright &y& Elsevier]