Evaluation of species-specific recA-based PCR tests for genomovar level identification within the Burkholderia cepacia complex

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Abstract
The Burkholderia cepacia complex presently comprises nine genomovars: B. cepacia (genomovar I), B. multivorans (genomovar II), B. cepacia genomovar III, B. stabilis (genomovar IV), B. vietnamiensis (genomovar V), B. cepacia genomovar VI, B. ambifaria (genomovar VII), B. anthina (genomovar VIII) and B. pyrrocinia (genomovar IX). Strains of each genomovar can colonise the respiratory tract of cystic fibrosis (CF) patients. However, the majority of infections in CF patients are caused by B. multivorans and B. cepacia genomovar III isolates. Accurate genomovar-level identification is best achieved through a polyphasic approach combining phenotypic and genotypic analyses. In the present study, the sensitivity and specificity of recA-based genomovar specific primer pairs were evaluated with a collection of 508 B. cepacia complex isolates representing all nine genomovars. The assays for the identification of B. multivorans (sensitivity and specificity, 100%), B. cepacia genomovar III (sensitivity, 92%; specificity, 100%), and B. ambifaria (sensitivity and specificity, 100%) were the most efficient. However, the B. cepacia genomovar I assay lacked sensitivity (72%) and cross-reacted with all B. pyrrocinia isolates examined. Several new recA RFLP types were also revealed within the B. cepacia complex. One of these profiles was shared by a clinical and an environmental B. cepacia-like isolate and by the B. ubonensis type strain. The latter organism is a recently described soil bacterium. Its relationship to the various B. cepacia complex genomovars needs further study.