Burkholderia, Stenotrophomonas, Ralstonia, Cupriavidus, Pandoraea, Brevundimonas, Comamonas, Delftia, and Acidovorax

Species in the genera Burkholderia, Stenotrophomonas, Ralstonia, Cupriavidus, Pandoraea, Brevundimonas, Comamonas, Delftia, and Acidovorax are unusual human pathogens that are infrequently encountered in the clinical microbiology laboratory. However, the incidence of human infection due to some of these species has increased in recent years. Further, the taxonomy of these genera has been expanded, with several new species being described. Burkholderia gladioli and members of the Burkholderia cepacia complex are important opportunistic pathogens in persons with cystic fibrosis and chronic granulomatous disease, while Burkholderia pseudomallei causes significant human infection in Southeast Asia and northern Australia. Stenotrophomonas maltophilia is an important nosocomial pathogen and, together with certain Ralstonia, Cupriavidus, and Pandoraea species, is also encountered in respiratory specimens from persons with cystic fibrosis. Historically, commercial phenotypic identification systems have performed rather poorly in identifying many of these species. Genetic-based identification methods have provided alternatives to traditional phenotypic analyses. More recently, matrix-assisted laser desorption ionization–time-of-flight mass spectrometry has shown excellent potential for reliable identification, which should continue to improve as libraries of reference spectra expand. A variety of genotyping systems provide for reliable strain typing of most of these species and have enabled a greater appreciation of the epidemiology and natural history of human infection. This group of species is also characterized by limited susceptibility to many currently available antimicrobials. Treatment of human infection is often empiric and relies on combined antimicrobial therapy.