John R. W. Govan

Evidence for transmission of Pseudomonas cepacia by social contact in cystic fibrosis

Pulmonary colonisation with Pseudomonas cepacia in patients with cystic fibrosis can be associated with increased morbidity and mortality. The modes of transmission of P cepacia are, however, unclear. We used selective media and phenotypic and genomic typing systems to investigate the acquisition of P cepacia by adults with cystic fibrosis. An analysis of isolates from 210 patients attending regional clinics in Edinburgh and Manchester between 1986 and 1992 showed that the main cause of increased isolations of P cepacia from 1989 was the emergence of an epidemic strain that had spread between patients in both clinics. Epidemiological evidence indicated that social contact was important in spread of the epidemic strain within and between clinics. We suggest that guidelines to limit the acquisition of P cepacia should not be restricted to patients in hospital, and that intimate or frequent social contact is associated with a high risk of cross-infection.

Classification of Alcaligenes faecalis-like isolates from the environment and human clinical samples as Ralstonia gilardii sp. nov.

A polyphasic taxonomic study that included DNA-DNA hybridizations, DNA base ratio determinations, 16S rDNA sequence analysis, whole-cell protein and fatty acid analyses, AFLP (amplified fragment length polymorphism) fingerprinting and an extensive biochemical characterization was performed on 10 strains provisionally identified as Alcaligenes faecalis-like bacteria. The six environmental and four human isolates belonged to the genus Ralstonia and were assigned to a new species for which the name Ralstonia gilardii sp. nov. is proposed. The type strain is LMG 5886T.

The Genome of Burkholderia cenocepacia J2315, an Epidemic Pathogen of Cystic Fibrosis Patients

Bacterial infections of the lungs of cystic fibrosis (CF) patients cause major complications in the treatment of this common genetic disease. Burkholderia cenocepacia infection is particularly problematic since this organism has high levels of antibiotic resistance, making it difficult to eradicate; the resulting chronic infections are associated with severe declines in lung function and increased mortality rates. B. cenocepacia strain J2315 was isolated from a CF patient and is a member of the epidemic ET12 lineage that originated in Canada or the United Kingdom and spread to Europe. The 8.06-Mb genome of this highly transmissible pathogen comprises three circular chromosomes and a plasmid and encodes a broad array of functions typical of this metabolically versatile genus, as well as numerous virulence and drug resistance functions. Although B. cenocepacia strains can be isolated from soil and can be pathogenic to both plants and man, J2315 is representative of a lineage of B. cenocepacia rarely isolated from the environment and which spreads between CF patients. Comparative analysis revealed that ca. 21% of the genome is unique in comparison to other strains of B. cenocepacia, highlighting the genomic plasticity of this species. Pseudogenes in virulence determinants suggest that the pathogenic response of J2315 may have been recently selected to promote persistence in the CF lung. The J2315 genome contains evidence that its unique and highly adapted genetic content has played a significant role in its success as an epidemic CF pathogen.

Spread of a multiresistant strain of Pseudomonas aeruginosa in an adult cystic fibrosis clinic

We initiated a prospective surveillance study to investigate possible Pseudomonas aeruginosa cross-infection in our cystic fibrosis centre. We characterised isolates by pyocin typing and pulsed-field gel electrophoresis. 22 (14%) of 154 patients with chronic P aeruginosa had isolates with similar and new pyocin and pulsed-field gel electrophoresis types. The shared isolates showed unusual phenotypic features: they were non-pigmented, non-motile, and resistant to a number of antipseudomonal antibiotics. Cross-infection by a multiresistant P aeruginosa strain has therefore occurred in patients attending our cystic fibrosis centre. We recommend microbiological surveillance in other cystic fibrosis centres.

Burkholderia cenocepacia sp. nov.--a new twist to an old story.

DNA-DNA hybridisation experiments between isolates representing Burkholderia cepacia genomovar III recA lineages IIIA and IIIB reinforced the classification of both phylogenetic subgroups as a single genospecies, distinct from B. cepacia (genomovar I). A formal classification of B. cepacia genomovar III encompassing the recA lineages IIIA and IIIB, and the new recA lineages IIIC and IIID, as B. cenocepacia sp. nov., with LMG 16656 as the type strain, is proposed.

Short- and Long-Term Antibiotic Treatment Reduces Airway and Systemic Inflammation in Non–Cystic Fibrosis Bronchiectasis

RATIONALE The vicious cycle hypothesis of bronchiectasis argues that bacterial colonization leads to airway inflammation and progressive lung damage. The logical extension of this hypothesis is that acute or chronic antibiotic therapy should improve airway inflammation and clinical outcome. There are little data to support this hypothesis in patients with non-cystic fibrosis (CF) bronchiectasis. OBJECTIVES To determine whether acute or chronic antibiotic therapy improves airway inflammation and clinical outcome in non-CF bronchiectasis. METHODS The relationship between bacterial load and airway and systemic inflammation was investigated in 385 stable patients, 15 stable patients treated with intravenous antibiotics, and 34 patients with an exacerbation of bronchiectasis treated with intravenous antibiotics. Long-term antibiotic therapy was investigated using samples from a 12-month controlled trial of nebulized gentamicin. MEASUREMENTS AND MAIN RESULTS In stable patients, there was a direct relationship between airway bacterial load and markers of airway inflammation (P < 0.0001 for all analyses). High bacterial loads were associated with higher serum intercellular adhesion molecule-1, E-selectin, and vascular cell adhesion molecule-1 (P < 0.05 above bacterial load ≥1 × 10(7) cfu/ml). In stable patients, there was a direct relationship between bacterial load and the risk of subsequent exacerbations (odds ratio, 1.20; 95% confidence interval, 1.11-1.29; P < 0.0001) and severe exacerbations (odds ratio, 1.11; 95% confidence interval, 1.01-1.21; P = 0.02). Short- and long-term antibiotic treatments were associated with reductions in bacterial load, airways, and systemic inflammation. CONCLUSIONS High airway bacterial loads in non-CF bronchiectasis are associated with airway and systemic inflammation and a greater risk of exacerbations. Short- and long-term antibiotic therapy reduce markers of airways and systemic inflammation.

Burkholderia anthina sp. nov. and Burkholderia pyrrocinia, two additional Burkholderia cepacia complex bacteria, may confound results of new molecular diagnostic tools

Nineteen Burkholderia cepacia-like isolates of human and environmental origin could not be assigned to one of the seven currently established genomovars using recently developed molecular diagnostic tools for B. cepacia complex bacteria. Various genotypic and phenotypic characteristics were examined. The results of this polyphasic study allowed classification of the 19 isolates as an eighth B. cepacia complex genomovar (Burkholderia anthina sp. nov.) and to design tools for its identification in the diagnostic laboratory. In addition, new and published data for Burkholderia pyrrocinia indicated that this soil bacterium is also a member of the B. cepacia complex. This highlights another potential source for diagnostic problems with B. cepacia-like bacteria.

Elafin (elastase-specific inhibitor) has anti-microbial activity against gram-positive and gram-negative respiratory pathogens.

Elafin (elastase‐specific inhibitor) is a low molecular weight inhibitor of neutrophil elastase which is secreted in the lung. Using synthetic peptides corresponding to full‐length elafin (H2N‐1AVT.....95Q‐OH), the NH2‐terminal domain (H2N‐1AVT.....50K‐OH) and the COOH‐terminal domain (H2N‐51PGS.....95Q‐OH), we demonstrate that elafins anti‐elastase activity resides exclusively in the COOH‐terminus. Several characteristics of elafin suggest potential anti‐microbial activity. The anti‐microbial activity of elafin, and of its two structural domains, was tested against the respiratory pathogensPseudomonas aeruginosa and Staphylococcus aureus. Elafin killed both bacteria efficiently, with 93% killing of P. aeruginosa by 2.5 μM elafin and 48% killing of S. aureus by 25 μM elafin. For both organisms, full‐length elafin was required to optimise bacterial killing. These findings represent the first demonstration of co‐existent anti‐proteolytic and anti‐microbial functions for elafin.

Burkholderia cenocepacia and Burkholderia multivorans: influence on survival in cystic fibrosis

Introduction:Burkholderia cepacia infection has been associated with a poor prognosis for patients with cystic fibrosis (CF). It is now recognised that organisms classified as B cepacia comprise a number of distinct genomic species each known as a genomovar of the B cepacia complex (BCC). The outcome of infection for CF patients with individual genomovars is unknown. The clinical outcome of infection with the two most commonly isolated genomovars (B cenocepacia and B multivorans) was studied at a specialist CF centre between 1982 and 2003. Methods: The numbers of patients who progressed from initial to chronic infection were assessed. Control groups were created by matching patients with chronic BCC infection by percentage forced expiratory volume in 1 second with patients with Pseudomonas aeruginosa infection. Outcome measures were survival time, deaths from “cepacia syndrome”, rate of decline in spirometry and body mass index (BMI), and treatment requirements. Results: Forty nine patients had an initial infection with either B multivorans (n = 16) or B cenocepacia (n = 33); 8/16 and 31/33, respectively, developed chronic infection (p<0.001). Deaths from “cepacia syndrome” occurred in both BCC groups. Patients with B cenocepacia infection had a shorter survival than patients with P aeruginosa infection (p = 0.01). There was no difference in survival between CF patients infected with B multivorans and P aeruginosa. There were no observed differences in changes in spirometry and BMI or treatment requirements between the BCC groups and respective controls. Conclusion: In CF, the genomovar status of BCC may influence both the likelihood of progression from initial to chronic infection and the overall survival of the patients.

Multilocus Sequence Typing Scheme That Provides Both Species and Strain Differentiation for the Burkholderia cepacia Complex

ABSTRACT A single multilocus sequence typing (MLST) scheme was developed for precise characterization of the opportunistic pathogens of Burkholderia cepacia complex (BCC), a group composed of at least nine closely related species. Seven conserved housekeeping genes were selected after a comparison of five Burkholderia species, and a collection of strains was subjected to nucleotide sequence analysis using a nested PCR amplification approach for each gene. MLST differentiated all nine current BCC species and identified 114 sequence types within a collection of 119 strains. No differentiation was found between strains recovered from environmental or clinical sources. The improved resolution in strain identification offered by MLST was able to identify previously characterized epidemic strain lineages and also demonstrated the presence of four novel potential species groups within the complex. There was also evidence for recombination having an important role in the recent evolution of individual BCC species. This highly transferable, validated, MLST scheme provides a new means to assist in species identification as well as unambiguous strain discrimination of the BCC by a single approach. It is also the first MLST scheme designed at the outset to incorporate multiple species and should facilitate global epidemiological investigations of the BCC.