Elucidating Global Epidemiology of Burkholderia multivorans in Cases of Cystic Fibrosis by Multilocus Sequence Typing

Abstract

Burkholderia multivorans is a prominent B. cepacia complex (BCC) species causing infection in people with cystic fibrosis. Despite infection control measures being introduced to reduce the spread of BCC there is a continued emergence of infections by B. multivorans. Our objective was to analyze a global collection of B. multivorans isolates, comparing those from environmental and clinical sources with those from reported outbreaks. Multilocus sequence typing (MLST) was performed on 107 B. multivorans isolates to provide a detailed analysis of the global population biology of this species. MLST resolved 64 B. multivorans sequence types. Twelve of these were globally distributed and associated with human infection; two of these (ST-21 and ST-375) were also composed of environmental isolates. These global lineages included strains previously linked to large outbreaks (e.g., French epidemic clone ST-16). Though few environmental isolates of B. multivorans were available for analysis, of six strains identified, three were identical to strains recovered from cystic fibrosis (CF) infection. Although the ability of B. multivorans to cause CF outbreaks is known, our report here concerning the existence of globally distributed B. multivorans CF strains is a new observation for this emerging B. cepacia complex pathogen and suggests that certain strain types may be better adapted to human infection than others. Common transmission-associated risk factors were not obviously linked to the globally distributed strains; however, the overlap in strains recovered from water environments, industrial products, and human infection suggests that environmental sources may be an important reservoir for infection with B. multivorans.Burkholderia multivorans is one of at least nine closely related gram-negative species that comprise the B. cepacia complex (BCC) (35). Originally these species were considered to be onion pathogens and were subsequently found to possess many beneficial properties for agricultural use (25). However, after more than two decades they have come to be widely known to cause problematic pulmonary infections in vulnerable individuals, particularly in people with cystic fibrosis (CF) (9).B. multivorans and Burkholderia cenocepacia are the two predominant BCC species causing human infections, though bacteria from all currently defined BCC species have been cultured from CF sputum (19,26,28). However, most research has concentrated on B. cenocepacia, which is widely considered to be the most virulent BCC species, with much less information available on B. multivorans. Comparison of recent epidemiological surveys (4, 12, 28) with older studies (19,26,32) suggests that the proportion of BCC-infected CF patients infected with B. multivorans is rising relative to the proportions of infection with B. cenocepacia and the remaining BCC species, with prevalence in the United States ranging from 38% (28) to 51% (4) of BCC infections. This proportional rise is due to a decline in the total incidence of B. cenocepacia while B. m...

Pseudomonas aeruginosa transmission is infrequent in New Zealand cystic fibrosis clinics

“…Current infection control measures thus appear to protect patients from transmission in New Zealand clinics, except for the cohort presently attending Greenlane where a recent report also suggested cross-infection by Burkholderia multivorans may have taken place [29]. When interpreting these data, the small size of New Zealand CF clinics must be considered.…”

Development of a Multiple-Locus Variable-Number Tandem-Repeat Typing Scheme for Genetic Fingerprinting of Burkholderia cenocepacia and Application to Nationwide Epidemiological Analysis

“…While PCR-based methods and PFGE have successfully been applied to local epidemiology, large-scale analyses require more portable methods, such as MLST or MLVA. An MLST scheme based on seven housekeeping genes has been developed and applied to global epidemiological analyses (22,25). Also, the recA gene included in the MLST scheme allows the discrimination of species within the BCC.…”

Expanded Multilocus Sequence Typing for Burkholderia Species

“…The multilocus sequence typing (MLST) scheme for the Burkholderia cepacia complex has provided important insights into the population dynamics, diversity, and recombination events in this group of opportunistic pathogens (1)(2)(3)7). It has also been effective in identifying previously misclassified strains and has proved useful in the recent identification of seven novel species in the B. cepacia complex (9,10).…”