Epidemiology ofBurkholderia cepaciacomplex colonisation in cystic fibrosis patients

In Belgian cystic fibrosis (CF) clinics, sputum samples are evaluated on selective MAST medium routinely every 3 months. In this study, in 1993 and 1999, isolates were further examined by recA restriction fragment length polymorphism analysis and pulsed-field gel electrophoresis of genomic DNA restricted with SpeI. In 1993, 12 patients were colonised with Burkholderia cepacia complex (Bcc): B. cenocepacia (n=6), B. multivorans (n=3), B. stabilis (n=3). Four patients were colonised with the same B. cenocepacia strain; two with the same B. stabilis strain. After 5 yrs, three B. cenocepacia- and one B. multivorans-colonised patients had died. In 1999, Bcc was isolated in 12 patients: B. multivorans (n=9), B. stabilis (n=1) and B. cenocepacia (n=2). Three patients were colonised by the same B. multivorans strain. Compared to matched controls, the 5 yr outcome was poor; four B. cepacia patients died and none of the control patients died. Lung-function evolution was poor. In conclusion, the rate of colonisation in Belgian cystic fibrosis patients is stable and low. Burkholderia cenocepacia was most prevalent in 1993; Burkholderia multivorans in 1999. The cross-infection rate is low. Three patients had transient colonisation. The impact of Burkholderia cepacia complex on morbidity in the Belgian cystic fibrosis population is high and not limited to Burkholderia cenocepacia.

Ralstonia taiwanensis sp. nov., isolated from root nodules of Mimosa species and sputum of a cystic fibrosis patient

A polyphasic taxonomic study, including 16S rDNA sequence analysis, DNA-DNA hybridizations, DNA base ratio determinations, amplified 165 rDNA restriction analysis, whole-cell protein analyses and extensive biochemical characterization, was conducted to clarify the relationships of eight isolates from root nodules of Mimosa species and one isolate from sputum of a cystic fibrosis patient. All nine isolates were classified as a novel Ralstonia species, for which the name Ralstonia taiwanensis sp. nov. is proposed. The type strain is LMG 19424T (= CCUG 44338T). R. taiwanensis effectively nodulated the Mimosa species and is the first beta-proteobacterium that is known to be capable of root nodule formation and nitrogen fixation.

Burkholderia ambifaria sp. nov., a novel member of the Burkholderia cepacia complex including biocontrol and cystic fibrosis-related isolates

A polyphasic taxonomic study, including amplified fragment length polymorphism (AFLP) fingerprinting, DNA-DNA hybridizations, DNA base-ratio determinations, phylogenetic analysis, whole-cell fatty acid analyses and an extensive biochemical characterization, was performed on 19 Burkholderia cepacia-like isolates from the environment and cystic fibrosis (CF) patients. Several of the environmental isolates have attracted considerable interest due to their biocontrol properties. The polyphasic taxonomic data showed that the strains represent a new member of the B. cepacia complex, for which the name Burkholderia ambifaria sp. nov. is proposed. The type strain is strain LMG 19182T. B. ambifaria can be differentiated from the other members of the B. cepacia complex by means of AFLP fingerprinting, whole-cell fatty acid analysis, biochemical tests (including ornithine and lysine decarboxylase activity, acidification of sucrose and beta-haemolysis) and a newly developed recA gene-based PCR assay. 16S rDNA-based RFLP analysis and PCR tests allowed differentiation of B. ambifaria from Burkholderia multivorans, Burkholderia vietnamiensis and B. cepacia genomovar VI, but not from B. cepacia genomovars I and III and Burkholderia stabilis. The finding that this new taxon includes both strains isolated from CF patients and potentially useful biocontrol strains supports the general consensus that the large-scale use of biocontrol strains belonging to the B. cepacia complex would be ill-advised until more is known about their potential pathogenic mechanisms.

Burkholderia fungorum sp. nov. and Burkholderia caledonica sp. nov., two new species isolated from the environment, animals and human clinical samples

A polyphasic taxonomic study that included DNA-DNA hybridizations, DNA base ratio determinations, 16S rDNA sequence analyses, whole-cell protein and fatty acid analyses and an extensive biochemical characterization was performed on 16 strains isolated from the environment, animals and human clinical samples. The isolates belonged to the genus Burkholderia, were phylogenetically closely related to Burkholderia graminis, Burkholderia caribensis and Burkholderia phenazinium and had G+C contents between 61.9 and 62.2 mol%. Seven strains isolated from the rhizosphere were assigned to Burkholderia caledonica sp. nov. [type strain LMG 19076T (= CCUG 42236T)]. Nine strains isolated from the environment, animals and human clinical samples were assigned to Burkholderia fungorum sp. nov. [type strain LMG 16225T (= CCUG 31961T)]. Differential tests for B. graminis, B. caribensis, B. phenazinium, B. caledonica and B. fungorum include the following: assimilation of trehalose, citrate, DL-norleucine, adipate and sucrose; nitrate reduction; growth in the presence of 0.5% NaCl; and beta-galactosidase activity.

Outbreak of subclinical mastitis in a flock of dairy sheep associated with Burkholderia cepacia complex infection

An outbreak of subclinical mastitis in a flock of 620 milking sheep was investigated. Microbiological and epidemiological analyses identified the causative agent as belonging to the Burkholderia cepacia complex (formerly Pseudomonas cepacia). Every ewe in the milking flock was individually tested for subclinical mastitis on two separate occasions, 6 weeks apart, by the California (rapid) mastitis test (CMT). The proportion of CMT-positive ewes was 69 of 393 (17.6%) on the first sampling and 27 of 490 (5.5%) on the second sampling. Pure B. cepacia cultures identified with the API 20 NE system were grown from 64 of 96 (66.7%) CMT-positive ewes and from 1 of 33 (3.0%) CMT-negative ewes. Statistical analysis confirmed the significant association between a positive CMT result and a positive culture result for B. cepacia complex. Additional polyphasic taxonomic analyses of eight isolates showed that seven belonged to B. cepacia genomovar III; the remaining isolate was identified as Burkholderia vietnamiensis (formerly B. cepacia genomovar V). Bacteriological investigation of samples from milking equipment and other environmental sites failed to identify "B. cepacia" in any of the samples taken. To our knowledge, this is the first report of an outbreak of natural infection in animals caused by B. cepacia complex and the first description of B. cepacia complex infection in sheep.

Burkholderia cepacia genomovar III Is a common plant-associated bacterium

A polyphasic taxonomic study involving DNA-DNA hybridization, whole-cell protein electrophoresis, and 16S ribosomal DNA sequence analysis revealed that a group of Burkholderia cepacia-like organisms isolated from the rhizosphere or tissues of maize, wheat, and lupine belong to B. cepacia genomovar III, a genomic species associated with "cepacia syndrome" in cystic fibrosis patients. The present study also revealed considerable protein electrophoretic heterogeneity within this species and demonstrated that the B. cepacia complex consists of two independent phylogenetic lineages.

Burkholderia cepacia complex: distribution of genomovars among isolates from the maize rhizosphere in Italy

Burkholderia cepacia is a 'complex' in which seven genomic species or genomovars have so far been identified. It appears that all seven B. cepacia genomovars are capable of causing infections in vulnerable persons; in particular, the importance of Burkholderia multivorans (genomovar II) and B. cepacia genomovar III among cystic fibrosis isolates, especially epidemic ones, has been emphasized. In order to acquire a better comprehension of the genomovar composition of environmental populations of B. cepacia, 120 strains were isolated from the rhizosphere of maize plants cultivated in fields located in northern, central and southern Italy. The identification of the different genomovars was accomplished by a combination of molecular polymerase chain reaction (PCR)-based techniques, such as restriction fragment length polymorphism (RFLP) analysis of 16S rDNA (ARDRA), genomovar-specific PCR tests and RFLP analyses based on polymorphisms in the recA gene whole-cell protein electrophoresis. ARDRA analysis allowed us to distinguish between all B. cepacia genomovars except B. cepacia genomovar I, B. cepacia genomovar III and Burkholderia ambifaria (genomovar VII). The latter genomovars were differentiated by means of recA PCR tests and RFLP analyses. Among the rhizospheric isolates of B. cepacia, we found only B. cepacia genomovar I, B. cepacia genomovar III, Burkholderia vietnamiensis (genomovar V) and B. ambifaria. B. cepacia genomovars I and III and B. ambifaria were recovered from all three fields, whereas B. vietnamiensis was detected only in the population isolated from the field located in central Italy. Among strains isolated from northern and southern Italy, the most abundant genomovars were B. ambifaria and B. cepacia genomovar III respectively; in contrast, the population isolated in central Italy showed an even distribution of strains among genomovars. These results indicate that it is not possible to differentiate clinical and environmental strains, or pathogenic and non-pathogenic strains, of the B. cepacia complex simply on the basis of genomovar status, and that the environment may serve as a reservoir for B. cepacia genomovar III infections in vulnerable humans.

Genotypic and chemotaxonomic evidence for the reclassification of Pseudomonas woodsii (Smith 1911) Stevens 1925 as Burkholderia andropogonis (Smith 1911) Gillis et al. 1995

It was reported before that [Pseudomonas] woodsii and Burkholderia andropogonis are phenotypically indistinguishable and probably represent the same taxon, for which the name B. andropogonis has been proposed. In the present study, it was found that [P.] woodsii and B. andropogonis strains were indistinguishable by whole-cell protein electrophoresis and have a highly similar cellular fatty acid composition. A high DNA-DNA binding value of 95% was found between the type strains of both species. In addition, the 16S rDNA sequence of [P.] woodsii strain LMG 2362T was very similar to that of B. andropogonis LMG 2129T (99.0%). The chemotaxonomic and genotypic data confirm that [P.] woodsii and B. andropogonis represent the same species, for which it is proposed to retain the name B. andropogonis.

Distinguishing species of the Burkholderia cepacia complex and Burkholderia gladioli by automated ribotyping

Several species belonging to the genus Burkholderia are clinically relevant, opportunistic pathogens that inhabit major environmental reservoirs. Consequently, the availability of means for adequate identification and epidemiological characterization of individual environmental or clinical isolates is mandatory. In the present communication we describe the use of the Riboprinter microbial characterization system (Qualicon, Warwick, United Kingdom) for automated ribotyping of 104 strains of Burkholderia species from diverse sources, including several publicly accessible collections. The main outcome of this analysis was that all strains were typeable and that strains of Burkholderia gladioli and of each species of the B. cepacia complex, including B. multivorans, B. stabilis, and B. vietnamiensis, were effectively discriminated. Furthermore, different ribotypes were discerned within each species. Ribotyping results were in general agreement with strain classification based on restriction fragment analysis of 16S ribosomal amplicons, but the resolution of ribotyping was much higher. This enabled automated molecular typing below the species level. Cluster analysis of the patterns obtained by ribotyping (riboprints) showed that within B. gladioli, B. multivorans, and B. cepacia genomovar VI, the different riboprints identified always clustered together. Riboprints of B. cepacia genomovars I and III, B. stabilis, and B. vietnamiensis did not show distinct clustering but rather exhibited the formation of loose assemblages within which several smaller, genomovar-specific clusters were delineated. Therefore, ribotyping proved useful for genomovar identification. Analysis of serial isolates from individual patients demonstrated that infection with a single ribotype had occurred, despite minor genetic differences that were detected by pulsed-field gel electrophoresis of DNA macrorestriction fragments. The automated approach allows very rapid and reliable identification and epidemiological characterization of strains and generates an easily manageable database suited for expansion with information on additional bacterial isolates.