D. Honeybourne

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.

Environmental Burkholderia cepacia complex isolates in human infections

Members of the Burkholderia cepacia complex (Bcc), found in many environments, are associated with clinical infections. Examining diverse species and strains from different environments with multilocus sequence typing, we identified >20% of 381 clinical isolates as indistinguishable from those in the environment. This finding links the natural environment with the emergence of many Bcc infections.

Association between Hypermutator Phenotype, Clinical Variables, Mucoid Phenotype, and Antimicrobial Resistance in Pseudomonas aeruginosa

ABSTRACT The presence of hypermutator Pseudomonas aeruginosa was associated with poorer lung function in patients at the Adult West Midlands CF Unit. Mucoid isolates were more likely to be hypermutators. The presence of resistant mutant subpopulations was associated with hypermutator phenotype but was not good enough to be used as a test for this phenotype.

Pseudomonas aeruginosa quorum sensing molecules correlate with clinical status in cystic fibrosis

Pseudomonas aeruginosa produces quorum sensing signal molecules that are potential biomarkers for infection. A prospective study of 60 cystic fibrosis patients with chronic P. aeruginosa, who required intravenous antibiotics for pulmonary exacerbations, was undertaken. Clinical measurements and biological samples were obtained at the start and end of the treatment period. Additional data were available for 29 of these patients when they were clinically stable. Cross-sectionally, quorum sensing signal molecules were detectable in the sputum, plasma and urine of 86%, 75% and 83% patients, respectively. They were positively correlated between the three biofluids. Positive correlations were observed for most quorum sensing signal molecules in sputum, plasma and urine, with quantitative measures of pulmonary P. aeruginosa load at the start of a pulmonary exacerbation. Plasma concentrations of 2-nonyl-4-hydroxy-quinoline (NHQ) were significantly higher at the start of a pulmonary exacerbation compared to clinical stability (p<0.01). Following the administration of systemic antibiotics, plasma 2-heptyl-4-hydroxyquinoline (p=0.02) and NHQ concentrations (p<0.01) decreased significantly. In conclusion, quorum sensing signal molecules are detectable in cystic fibrosis patients with pulmonary P. aeruginosa infection and are positively correlated with quantitative measures of P. aeruginosa. NHQ correlates with clinical status and has potential as a novel biomarker for P. aeruginosa infection. P. aeruginosa QS molecules correlate with clinical status in cystic fibrosis and are biomarkers for infection http://ow.ly/MhzZp

Quality of life and healthcare utilisation in cystic fibrosis: a multicentre study

The aim of our study was to discover the health status and healthcare utilisation associated with pulmonary exacerbations in cystic fibrosis (CF) and chronic Pseudomonas aeruginosa infection. Patients with CF from five UK CF centres attended two visits, 8–12 weeks apart. They were classified at visit 1 as being in one of the three health states: no current pulmonary exacerbation; “mild” (no hospitalisation) pulmonary exacerbation; and “severe” (hospitalisation) pulmonary exacerbation. All patients completed the Cystic Fibrosis Questionnaire-Revised (CFQ-R) and EuroQol (EQ-5D) and a clinical form, and forced expiratory volume in 1 s (FEV1) was measured at visits 1 and 2. Annual healthcare utilisation data were collected. 94 patients of mean±sd age 28.5±8.2 yrs and FEV1 58.7±26.8% were recruited. 60 patients had no pulmonary exacerbation, 15 had a mild and 19 had a severe pulmonary exacerbation at visit 1. EQ-5D and CFQ-R data showed that the worse the exacerbation, the poorer the health-related quality of life (HRQoL). There were strong relationships between the CFQ-R and EQ-5D domain scores. The mean rate of pulmonary exacerbations per patient per year was 3.6 (1.5 in hospital and 2.2 at home). The mean length of stay per hospital pulmonary exacerbation was 9 days. As exacerbation status worsens, patients experience worse HRQoL. There is a significant healthcare burden associated with treatment of pulmonary exacerbation and long-term prophylaxis.

Cross-Sectional and Longitudinal Multilocus Sequence Typing of Pseudomonas aeruginosa in Cystic Fibrosis Sputum Samples

ABSTRACT Multilocus sequence typing (MLST) is a genetic typing tool designed to provide information about the relatedness of isolates at the core genome level. The utility of MLST in regard to cystic fibrosis (CF)-related infection with Pseudomonas aeruginosa is unknown. The molecular clock speed of the MLST genes was studied using 219 colonies isolated longitudinally from 49 patients with CF. A cross-sectional study examining 27 to 46 colonies per sputum sample for samples from 16 patients was also undertaken. The molecular clock speed was estimated to be 2.05 × 10−5 (upper 95% confidence limit) or 4.75 × 10−6 (50% confidence limit) point mutations per nucleotide per year. In the cross-sectional study, 50% of patients were infected with more than one sequence type. There was evidence of point mutations, recombination events, and coinfection with epidemic and unique strains. A clonal complex that was highly genetically distinct from the rest of the P. aeruginosa population was identified. The MLST scheme uses genes with an appropriate clock speed and provides useful information about the genetic variation of P. aeruginosa within and between patients with CF.

Clinical outcomes of pandemic (H1N1) 2009 influenza (swine flu) in adults with cystic fibrosis.

Patients with cystic fibrosis (CF) suffer recurrent bacterial pulmonary infections, but viral infections can also cause acute clinical deterioration.1 Certain patient groups suffer increased morbidity following pandemic (H1N1) 2009 influenza (swine flu),2 but there are few previous reports of outcomes in individuals with CF.3 4 The West Midlands, along with Greater London, has had the highest incidence of H1N1 influenza in the UK.5 We therefore examined the outcomes of patients diagnosed with H1N1 influenza at the West Midlands Adult CF Centre. From June 2009 to April 2010 all adults with CF at our regional centre with potential H1N1 influenza had nasopharyngeal swabs tested …

Intussusception in Adults with Cystic Fibrosis: A Case Series with Review of the Literature

Intussusception occurs when a proximal segment of bowel (intussusceptum) telescopes into the lumen of the adjacent distal segment (intussuscepiens). It is a relatively common cause of an acute abdomen in the first two years of life, but is uncommon in older children [1]. The diagnosis is rare in adult life, with presentations in adulthood comprising 5% of all intussusceptions and 1% of bowel obstructions [2]. In children it is most commonly idiopathic, in contrast with adults, for most of whom an underlying etiology is found. Cystic fibrosis (CF) is the most common fatal inherited condition in Caucasians [3]. It is caused by abnormal function of the cystic fibrosis transmembrane conductance regulator (CFTR), an epithelial chloride channel. This primary defect causes epithelial secretions to be abnormally dehydrated and viscous, affecting several organs including the lungs, pancreas, intestines, and liver. CF is a well-recognized risk factor for childhood intussusception, with an incidence of 1% reported in the largest case series [4]. The peak age of presentation in this case series was between 9 and 12 years of age, much older than in the nonCF population. Although the clinical presentation and management of intussusception in children with CF is well described, that of adults is less well characterized. We therefore present a case series of CF adults diagnosed with symptomatic intussusception at our centers and perform a systematic review of the literature in order to identify previously described cases. Our aim is to examine the clinical and imaging findings of intussusception in CF adults in order to identify features of the presentation that should suggest this diagnosis.

Commercial Mushrooms and Bean Sprouts Are a Source of Pseudomonas aeruginosa

Although Pseudomonas aeruginosa is widely reported to be ubiquitous in the environment, attempts to reliably isolate this opportunistic pathogen from environmental sources have often had limited success. In many cases, if present, P. aeruginosa is not detectable in quantifiable amounts and requires

Diagnostic and prognostic significance of systemic alkyl quinolones for P. aeruginosa in cystic fibrosis: a longitudinal study

Background Pulmonary P. aeruginosa infection is associated with poor outcomes in cystic fibrosis (CF) and early diagnosis is challenging, particularly in those who are unable to expectorate sputum. Specific P. aeruginosa 2-alkyl-4-quinolones are detectable in the sputum, plasma and urine of adults with CF, suggesting that they have potential as biomarkers for P. aeruginosa infection. Aim To investigate systemic 2-alkyl-4-quinolones as potential biomarkers for pulmonary P. aeruginosa infection. Methods A multicentre observational study of 176 adults and 68 children with CF. Cross-sectionally, comparisons were made between current P. aeruginosa infection using six 2-alkyl-4-quinolones detected in sputum, plasma and urine against hospital microbiological culture results. All participants without P. aeruginosa infection at baseline were followed up for one year to determine if 2-alkyl-4-quinolones were early biomarkers of pulmonary P. aeruginosa infection. Results Cross-sectional analysis: the most promising biomarker with the greatest diagnostic accuracy was 2-heptyl-4-hydroxyquinoline (HHQ). In adults, areas under the ROC curves (95% confidence intervals) for HHQ analyses were 0.82 (0.75–0.89) in sputum, 0.76 (0.69–0.82) in plasma and 0.82 (0.77–0.88) in urine. In children, the corresponding values for HHQ analyses were 0.88 (0.77–0.99) in plasma and 0.83 (0.68–0.97) in urine. Longitudinal analysis: Ten adults and six children had a new positive respiratory culture for P. aeruginosa in follow-up. A positive plasma HHQ test at baseline was significantly associated with a new positive culture for P. aeruginosa in both adults and children in follow-up (odds ratio (OR) = 6.67;-95% CI:-1.48–30.1;-p = 0.01 and OR = 70; 95% CI: 5–956;-p < 0.001 respectively). Conclusions AQs measured in sputum, plasma and urine may be used to diagnose current infection with P. aeruginosa in adults and children with CF. These preliminary data show that plasma HHQ may have potential as an early biomarker of pulmonary P. aeruginosa. Further studies are necessary to evaluate if HHQ could be used in clinical practice to aid early diagnosis of P. aeruginosa infection in the future.