Extensive cultivation of soil and water samples yields various pathogens in patients with cystic fibrosis but not Burkholderia multivorans.

BACKGROUND: While the epidemiology of Burkholderia cepacia complex (Bcc) bacteria in cystic fibrosis (CF) patients suggests that Burkholderia multivorans is acquired from environmental sources, this species has rarely been isolated from soil and water samples. METHODS: Multiple isolation strategies were applied to water and soil samples that were previously shown to be B. multivorans PCR positive. These included direct plating and liquid enrichment procedures and the use of selective media, acclimatizing recovery and co-cultivation with CF sputum. MALDI-TOF mass spectrometry and sequence analysis of 16S rRNA and housekeeping genes were used to identify all isolates. RESULTS: None of the approaches yielded B. multivorans isolates. Other Burkholderia species, several Gram-negative non-fermenting bacteria (including Cupriavidus, Inquilinus, Pandoraea, Pseudomonas and Stenotrophomonas) and rapidly growing mycobacteria (including Mycobacterium chelonae) were all isolated from water and soil samples. CONCLUSIONS: The use of Bcc isolation media yielded a surprisingly wide array of rare but often clinically relevant CF pathogens, confirming that soil and water are reservoirs of these infectious agents.