Individual Cystic Fibrosis Patients Research Articles

Clinically undetected polyclonal heteroresistance among Pseudomonas aeruginosa isolated from cystic fibrosis respiratory specimens.

Pseudomonas aeruginosa infection is the leading cause of death among patients with cystic fibrosis (CF) and a common cause of difficult-to-treat hospital-acquired infections. P. aeruginosa uses several mechanisms to resist different antibiotic classes and an individual CF patient can harbour multiple resistance phenotypes. To determine the rates and distribution of polyclonal heteroresistance (PHR) in P. aeruginosa by random, prospective evaluation of respiratory cultures from CF patients at a large referral centre over a 1 year period. We obtained 28 unique sputum samples from 19 CF patients and took multiple isolates from each, even when morphologically similar, yielding 280 unique isolates. We performed antimicrobial susceptibility testing (AST) on all isolates and calculated PHR on the basis of variability in AST in a given sample. We then performed whole-genome sequencing on 134 isolates and used a machine-learning association model to interrogate phenotypic PHR from genomic data. PHR was identified in most sampled patients (n = 15/19; 79%). Importantly, resistant phenotypes were not detected by routine AST in 26% of patients (n = 5/19). The machine-learning model, using the extended sampling, identified at least one genetic variant associated with phenotypic resistance in 94.3% of isolates (n = 1392/1476). PHR is common among P. aeruginosa in the CF lung. While traditional microbiological methods often fail to detect resistant subpopulations, extended sampling of isolates and conventional AST identified PHR in most patients. A machine-learning tool successfully identified at least one resistance variant in almost all resistant isolates by leveraging this extended sampling and conventional AST.

Oral Care Recommendation for Cystic Fibrosis Patients-Recommendation for Dentists.

Cystic fibrosis (CF) is a genetic disease that is caused by a defect in the gene coding for the transmembrane cystic fibrosis transmembrane conductance regulator (CFTR). Research papers published so far point out that despite the numerous dental treatment needs of CF patients, there are no oral care guidelines for this group of patients. The aim of the article is to propose standards of dental prophylactic and therapeutic procedures for CF patients in different age groups. Regardless of the CF patient’s age, dental check-ups should be scheduled at least every 6 months. However, taking into account the actual condition of the individual CF patients, therapeutic visits may be scheduled for earlier dates, to provide well-fitting treatment, considering the level of risk of oral diseases. The described management standards may be helpful and may improve the quality of dental care provided to CF patients.

High Nuclease Activity of Long Persisting Staphylococcus aureus Isolates Within the Airways of Cystic Fibrosis Patients Protects Against NET-Mediated Killing.

Staphylococcus aureus is one of the first and most prevalent pathogens cultured from the airways of cystic fibrosis (CF) patients, which can persist there for extended periods. Airway infections in CF patients are characterized by a strong inflammatory response of highly recruited neutrophils. One killing mechanism of neutrophils is the formation of neutrophil extracellular traps (NETs), which capture and eradicate bacteria by extracellular fibers of neutrophil chromatin decorated with antimicrobial granule proteins. S. aureus secretes nuclease, which can degrade NETs. We hypothesized, that S. aureus adapts to the airways of CF patients during persistent infection by escaping from NET-mediated killing via an increase of nuclease activity. Sputum samples of CF patients with chronic S. aureus infection were visualized by confocal microscopy after immuno-fluorescence staining for NET-specific markers, S. aureus bacteria and overall DNA structures. Nuclease activity was analyzed in sequential isogenic long persisting S. aureus isolates, as confirmed by whole genome sequencing, from an individual CF patient using a FRET-based nuclease activity assay. Additionally, some of these isolates were selected and analyzed by qRT-PCR to determine the expression of nuc1 and regulators of interest. NET-killing assays were performed with clinical S. aureus isolates to evaluate killing and bacterial survival depending on nuclease activity. To confirm the role of nuclease during NET-mediated killing, a clinical isolate with low nuclease activity was transformed with a nuclease expression vector (pCM28nuc). Furthermore, two sputa from an individual CF patient were subjected to RNA-sequence analysis to evaluate the activity of nuclease in vivo. In sputa, S. aureus was associated to extracellular DNA structures. Nuclease activity in clinical S. aureus isolates increased in a time-and phenotype-dependent manner. In the clinical isolates, the expression of nuc1 was inversely correlated to the activity of agr and was independent of saeS. NET-mediated killing was significantly higher in S. aureus isolates with low compared to isolates with high nuclease activity. Importantly, transformation of the clinical isolate with low nuclease activity with pCM28nuc conferred protection against NET-mediated killing confirming the beneficial role of nuclease for protection against NETs. Also, nuclease expression in in vivo sputa was high, which underlines the important role of nuclease within the highly inflamed CF airways. In conclusion, our data show that S. aureus adapts to the neutrophil-rich environment of CF airways with increasing nuclease expression most likely to avoid NET-killing during long-term persistence.

Development and external validation of 1-and 2-year mortality prediction models in cystic fibrosis.

We aimed to develop a clinical tool for predicting 1- and 2-year risk of death for patients with cystic fibrosis (CF). The model considers patients' overall health status as well as risk of intermittent shock events in calculating the risk of death. Canadian CF Registry data from 1982 to 2015 were used to develop a predictive risk model using threshold regression. A 2-year risk of death estimated conditional probability of surviving the second year given survival for the first year. UK CF Registry data from 2007 to 2013 were used to externally validate the model. The combined effect of CF chronic health status and CF intermittent shock risk provided a simple clinical scoring tool for assessing 1-year and 2-year risk of death for an individual CF patient. At a threshold risk of death of ≥20%, the 1-year model had a sensitivity of 74% and specificity of 96%. The area under the receiver operating curve (AUC) for the 2-year mortality model was significantly greater than the AUC for a model that predicted survival based on forced expiratory volume in 1 s <30% predicted (AUC 0.95 versus 0.68 respectively, p<0.001). The Canadian-derived model validated well with the UK data and correctly identified 79% of deaths and 95% of survivors in a single year in the UK. The prediction models provide an accurate risk of death over a 1- and 2-year time horizon. The models performed equally well when validated in an independent UK CF population.

Higher Interleukin-7 serum concentrations in patients with cystic fibrosis correlate with impaired lung function

BackgroundPatients with cystic fibrosis (CF) are highly susceptible to infection and colonization of pulmonary epithelia. Repeated and chronic infections may affect disease course and efficacy of host immune protection. Higher Interleukin (IL)-7 serum levels, indicating impaired T-cell response to IL-7, have been described for chronic viral and mycobacterial infections. MethodsTime course measures of IL-7 serum concentrations in patients with CF (n = 164; n = 78 for the second time point) and healthy controls (n = 60) were done. CF patients were characterized for disease severity parameters as well as infection status and association with IL-7 serum levels was determined. ResultsCF patients had significantly higher IL-7 serum concentrations as compared to healthy controls (9.79 pg/ml, IQR 6.76–13.6 versus 4.55 pg/ml, IQR 2.76–9.51, p < .001). IL-7 serum levels were negatively correlated with individual CF patient's BMI (r = −0.19, p = .021) and a tendency of increased IL-7 levels in Staphylococcus aureus infected CF patients was found. Linear regression of multiple parameters revealed significant negative correlation of FEV1%pred with IL-7 serum concentrations in patients with CF (ß-coefficient: −0.04, 95% confidence interval [−0.08; −0.003], p = .034). Time course analyses after 1 year +/− 6 months showed increased IL-7 serum levels (time point 1:9.26 pg/ml, IQR 6.94–13.12 time point 2:10.86 pg/ml, IQR 9.14–14.76, p = .016) that correlated negatively with decreased FEV1%pred during CF disease course. ConclusionsHigh IL-7 serum levels were found in CF patients and correlated with impaired lung function during CF disease course. As a candidate biomarker of T-cell dysfunction, higher IL-7 serum level may also indicate worsened immune competence of patients with CF.

Nasospheroids permit measurements of CFTR-dependent fluid transport.

Expansion of novel therapeutics to all patients with cystic fibrosis (CF) requires personalized CFTR modulator therapy. We have developed nasospheroids, a primary cell culture-based model derived from individual CF patients and healthy subjects by a minimally invasive nasal biopsy. Confocal microscopy was utilized to measure CFTR activity by analyzing changes in cross-sectional area over time that resulted from CFTR-mediated ion and fluid movement. Both the rate of change over time and AUC were calculated. Non-CF nasospheroids with active CFTR-mediated ion and fluid movement showed a reduction in cross-sectional area, whereas no changes were observed in CF spheroids. Non-CF spheroids treated with CFTR inhibitor lost responsiveness for CFTR activation. However, nasospheroids from F508del CF homozygotes that were treated with lumacaftor and ivacaftor showed a significant reduction in cross-sectional area, indicating pharmacologic rescue of CFTR function. This model employs a simple measurement of size corresponding to changes in CFTR activity and is applicable for detection of small changes in CFTR activity from individual patients in vitro. Advancements of this technique will provide a robust model for individualized prediction of CFTR modulator efficacy.

Advances in Imaging Cystic Fibrosis Lung Disease.

Cystic fibrosis (CF) is a life shortening, multiorgan disease, in which morbidity and mortality are dominated by pulmonary pathologies, including mucous obstruction, chronic lung infections, progressive bronchiectasis, and declining lung function. Promising new therapies, including those that target the cystic fibrosis transmembrane conductance regulator (CFTR) protein, have shown impressive efficacy in treating CF patients with specific genotypes. While spirometry is the clinical gold standard for evaluating CF lung disease, it has known insensitivities to mild lung disease and statistical weaknesses in small cohorts. Imaging has begun to play an important role in evaluating the structural abnormalities associated with CF lung disease progression. X-ray computed tomography (CT) has been established as a modality with validated metrics to evaluate disease severity, even in young patients with mild disease. Magnetic resonance imaging (MRI), as a nonionizing alternative, has very strong potential for similar metrics and longitudinal use through the lifespan. In this brief review, recent advancements in imaging CF lung disease in pediatrics are discussed, specifically in the contexts of X-ray CT, ultra-short echo time MRI, and hyperpolarized-gas MRI, with an emphasis on how emerging techniques will likely impact the management of CF lung disease in the era of CFTR-modulator therapies, targeted at smaller subpopulations of CF with specific genotypes. In the future, techniques that provide sensitive, quantitative measurements of regional lung structure and function longitudinally will become increasingly important as outcome measures for clinical trials and for monitoring individual CF patients.

Understanding Pulmonary Cystic Fibrosis

The genetic basis for cystic fibrosis is well-characterized, severe monogenic recessive disorder, that arises from mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene.There are several molecules that interact with CFTR gene, such as ORCC, ENaC, ROMK2, Aquaporin 3 (AQP3), NKCC1, NBC-1, Syntaxin 1A, and NHERF/EBP50. The ORCC molecule outwardly rectifies the chloride channel. Since 1989, more than 1,500 specific gene mutations and DNA sequence variations have been identified in CFTR gene. The Delta F508 mutation is the most common and is identified in almost all racial and ethnic groups ( approximately 70% of all cystic fibrosis genes). The sweat ducts of the patients are impermeable to the chloride ions, thus, the sodium chloride remains in the secretions contributing the salty sweat.Typical symptoms includes salty-tasting skin, wheezing or shortness of breath, frequent lung and par nasal sinus infections, nasal polyps, poor growth and poor weight gain, swollen belly accompanied by abdominal gas and discomfort, and broadening of the fingertips and toes. A sweat chloride concentration of more than 60 mmol/liter determined on two or more occasions by quantitative pilocarpineionophoresis remains the “gold standard” for diagnosis, but false-negative sweat tests can also be a consequence of the particular combination of CFTR mutations carried by an individual cystic fibrosis patient. The genetic testing is available, but is not commonly used because it cannot detect all gene mutations ( approximately 70-75% of the detection rate).

A statistical model to predict one-year risk of death in patients with cystic fibrosis

ObjectivesWe constructed a statistical model to assess the risk of death for cystic fibrosis (CF) patients between scheduled annual clinical visits. Our model includes a CF health index that shows the influence of risk factors on CF chronic health and on the severity and frequency of CF exacerbations. Study Design and SettingOur study used Canadian CF registry data for 3,794 CF patients born after 1970. Data up to 2010 were analyzed, yielding 44,390 annual visit records. Our stochastic process model postulates that CF health between annual clinical visits is a superposition of chronic disease progression and an exacerbation shock stream. Death occurs when an exacerbation carries CF health across a critical threshold. The data constitute censored survival data, and hence, threshold regression was used to connect CF death to study covariates. Maximum likelihood estimates were used to determine which clinical covariates were included within the regression functions for both CF chronic health and CF exacerbations. ResultsLung function, Pseudomonas aeruginosa infection, CF-related diabetes, weight deficiency, pancreatic insufficiency, and the deltaF508 homozygous mutation were significantly associated with CF chronic health status. Lung function, age, gender, age at CF diagnosis, P aeruginosa infection, body mass index <18.5, number of previous hospitalizations for CF exacerbations in the preceding year, and decline in forced expiratory volume in 1 second in the preceding year were significantly associated with CF exacerbations. When combined in one summative model, the regression functions for CF chronic health and CF exacerbation risk provided a simple clinical scoring tool for assessing 1-year risk of death for an individual CF patient. Goodness-of-fit tests of the model showed very encouraging results. We confirmed predictive validity of the model by comparing actual and estimated deaths in repeated hold-out samples from the data set and showed excellent agreement between estimated and actual mortality. ConclusionOur threshold regression model incorporates a composite CF chronic health status index and an exacerbation risk index to produce an accurate clinical scoring tool for prediction of 1-year survival of CF patients. Our tool can be used by clinicians to decide on optimal timing for lung transplant referral.

Unique microbial communities persist in individual cystic fibrosis patients throughout a clinical exacerbation

BackgroundCystic fibrosis (CF) is caused by inherited mutations in the cystic fibrosis transmembrane conductance regulator gene and results in a lung environment that is highly conducive to polymicrobial infection. Over a lifetime, decreasing bacterial diversity and the presence of Pseudomonas aeruginosa in the lung are correlated with worsening lung disease. However, to date, no change in community diversity, overall microbial load or individual microbes has been shown to correlate with the onset of an acute exacerbation in CF patients. We followed 17 adult CF patients throughout the course of clinical exacerbation, treatment and recovery, using deep sequencing and quantitative PCR to characterize spontaneously expectorated sputum samplesResultsWe identified approximately 170 bacterial genera, 12 of which accounted for over 90% of the total bacterial load across all patient samples. Genera abundant in any single patient sample tended to be detectable in most samples. We found that clinical stages could not be distinguished by absolute Pseudomonas aeruginosa load, absolute total bacterial load or the relative abundance of any individual genus detected, or community diversity. Instead, we found that the microbial structure of each patient’s sputum microbiome was distinct and resilient to exacerbation and antibiotic treatment.ConclusionConsistent with previously reported sputum microbiome studies we found that total and relative abundance of genera at the population level were remarkably stable for individual patients regardless of clinical status. Patient-by-patient analysis of diversity and relative abundance of each individual genus revealed a complex microbial landscape and highlighted the difficulty of identifying a universal microbial signature of exacerbation. Overall, at the genus level, we find no evidence of a microbial signature of clinical stage.

Pseudomonas aeruginosa Syntrophy in Chronically Colonized Airways of Cystic Fibrosis Patients

Pseudomonas aeruginosa isolates from cystic fibrosis (CF) patients undergo remarkable phenotypic divergence over time, including loss of pigmentation, hemolysis, motility, and quorum sensing and emergence of antibiotic hypersusceptibility and/or auxotrophism. With prolonged antibiotic treatment and steady decline in lung function in chronically infected patients, the divergent characteristics associated with CF isolates have traditionally been regarded as "adapted/unusual virulence," despite the degenerative nature of these adaptations. We examined the phenotypic and genotypic diversity in clonally related isogenic strains of P. aeruginosa from individual CF patients. Our observations support a novel model of intra-airway pseudomonal syntrophy and accompanying loss of virulence. A 2007 calendar year collection of CF P. aeruginosa isolates (n = 525) from 103 CF patients yielded in vitro MICs of sulfamethoxazole-trimethoprim (SMX-TMP, which typically has no activity against P. aeruginosa) ranging from 0.02 to >32 μg/ml (median, 1.5). Coisolation of clonally related SMX-TMP-susceptible and -resistant P. aeruginosa strains from the same host was common (57%), as were isogenic coisolates with mutations in efflux gene determinants (mexR, mexAB-oprM, and mexZ) and genes governing DNA mismatch repair (mutL and mutS). In this cohort, complete in vitro growth complementation between auxotrophic and prototrophic P. aeruginosa isogenic strains was evident and concurrent with the coding sequence mosaicism in resistance determinants. These observations suggest that syntrophic clonal strains evolve in situ in an organized colonial structure. We propose that P. aeruginosa adopts a multicellular lifestyle in CF patients due to host selection of an energetically favorable, less-virulent microbe restricted within and symbiotic with the airway over the host's lifetime.

Molecular Fingerprinting of Mycobacterium abscessus Strains in a Cohort of Pediatric Cystic Fibrosis Patients

Forty-one Mycobacterium abscessus complex isolates from 17 pediatric cystic fibrosis (CF) patients were typed using a novel variable-number tandem repeat (VNTR) scheme and an automated repetitive-PCR (rep-PCR) system. Both VNTR and rep-PCR typing methods differentiate between members of the M. abscessus complex. The isolates from individual patients are indistinguishable, and the data strongly suggest that individual CF patients are persistently infected with one strain and also suggests that different CF patients can harbor the same strain.

Evolutionary dynamics of bacteria in a human host environment

Laboratory evolution experiments have led to important findings relating organism adaptation and genomic evolution. However, continuous monitoring of long-term evolution has been lacking for natural systems, limiting our understanding of these processes in situ. Here we characterize the evolutionary dynamics of a lineage of a clinically important opportunistic bacterial pathogen, Pseudomonas aeruginosa, as it adapts to the airways of several individual cystic fibrosis patients over 200,000 bacterial generations, and provide estimates of mutation rates of bacteria in a natural environment. In contrast to predictions based on in vitro evolution experiments, we document limited diversification of the evolving lineage despite a highly structured and complex host environment. Notably, the lineage went through an initial period of rapid adaptation caused by a small number of mutations with pleiotropic effects, followed by a period of genetic drift with limited phenotypic change and a genomic signature of negative selection, suggesting that the evolving lineage has reached a major adaptive peak in the fitness landscape. This contrasts with previous findings of continued positive selection from long-term in vitro evolution experiments. The evolved phenotype of the infecting bacteria further suggests that the opportunistic pathogen has transitioned to become a primary pathogen for cystic fibrosis patients.

Pseudomonas aeruginosa Cystic Fibrosis Isolates from Individual Patients Demonstrate a Range of Levels of Lethality in Two Drosophila melanogaster Infection Models

Recently, two Drosophila melanogaster models of infection, fly feeding and fly nicking, have been developed that allow a determination of pathogenic potential of Pseudomonas aeruginosa isolates. In this study, control strains, isolates from burn wounds, and isolates from the sputa of cystic fibrosis (CF) patients were used to compare the two infection models to determine whether any of the isolates might be better adapted to either of the models. In addition, our goal was to determine the variability of isolates from individual CF patients. Three of four control strains (PAO1, PAK, and PA14) caused significant mortality in the flies in both models of infection. The remaining control strain, PA103, was lethal to flies in the nicking model but lacked significant lethality in the feeding model. The burn wound isolates had a high level of lethality in both models. Interestingly, the CF isolates had the largest diversity of lethality in both models of infection. The range of pathogenic potentials of the CF isolates occurred across a cohort of patients, both at the patient level and down to the level of individual sputum samples. The majority of all isolates had similar levels of lethality in both fly infection models. However, two CF isolates were significantly more lethal in the nicking model, and three CF isolates were significantly more lethal in the feeding model. In conclusion, the two Drosophila infection models were useful for the analysis of the diversity of pathogenic potentials of P. aeruginosa isolates.

Genome mosaicism is conserved but not unique in Pseudomonas aeruginosa isolates from the airways of young children with cystic fibrosis.

Pseudomonas aeruginosa strains from the chronic lung infections of cystic fibrosis (CF) patients are phenotypically and genotypically diverse. Using strain PAO1 whole genome DNA microarrays, we assessed the genomic variation in P. aeruginosa strains isolated from young children with CF (6 months to 8 years of age) as well as from the environment. Eighty-nine to 97% of the PAO1 open reading frames were detected in 20 strains by microarray analysis, while subsets of 38 gene islands were absent or divergent. No specific pattern of genome mosaicism defined strains associated with CF. Many mosaic regions were distinguished by their low G + C content; their inclusion of phage related or pyocin genes; or by their linkage to a vgr gene or a tRNA gene. Microarray and phenotypic analysis of sequential isolates from individual patients revealed two deletions of greater than 100 kbp formed during evolution in the lung. The gene loss in these sequential isolates raises the possibility that acquisition of pyomelanin production and loss of pyoverdin uptake each may be of adaptive significance. Further characterization of P. aeruginosa diversity within the airways of individual CF patients may reveal common adaptations, perhaps mediated by gene loss, that suggest new opportunities for therapy.

Simple and inexpensive but highly discriminating method for computer-assisted DNA fingerprinting of Pseudomonas aeruginosa.

We describe here a method for computer-assisted fingerprinting of Pseudomonas aeruginosa. In this method, DNA is digested with SalI, and bands with molecular sizes of >/=9.7 kb are visually scored after electrophoresis on agarose gels. Pattern scores are entered into a Microsoft Excel database. In scoring, the number of bands within each of a set of molecular size ranges is scored, rather than the absolute molecular size of each band, substantially enhancing the speed and reproducibility of the method, while eliminating the need for using expensive gel scanning equipment and software. Pattern scores are used to generate matrices of genetic distance values, which can be visualized in neighbor-joining trees. The method reliably distinguishes two epidemiologically unrelated isolates in 99.3% of all comparisons. The genetic relationships between isolates observed with the method were consistent with those obtained by analysis of two P. aeruginosa genes, indicating that it provides valid estimates of genetic divergence between isolates. Using the method, respiratory tract isolates from cystic fibrosis patients in Green Lane Hospital in Auckland, New Zealand, were shown to be genetically less diverse than epidemiologically unrelated isolates from other patients. This finding was not due to the existence of clusters of related strains specialized toward colonization of the respiratory tract and thus was indicative of transmission between patients. Analysis of multiple isolates from individual cystic fibrosis patients suggested that up to five separate clusters of genetically related strains may simultaneously be present in a patient. The method described should significantly enhance our ability to investigate the epidemiology of P. aeruginosa.

An easy microtiter assay for quantitation of cytokine induction by lipopolysaccharide (LPS) and activity of LPS-binding serum components.

Lipopolysaccharide (LPS, endotoxin) is a major inducer of cytokines, such as interleukin 1 (IL1), IL6, IL8 and tumor necrosis factor (TNF). A convenient microtiter assay was developed to measure such activity. LPS coated onto a plastic surface was used to stimulate purified human mononuclear cells (MNC) in microtiter plates. Following stimulation the supernatants were assayed for presence of TNF by ELISA. Purified rough and smooth LPS from Pseudomonas aeruginosa gave a dose-dependent TNF release over a range of 0.1-1.0 microgram LPS/well. The assay was subsequently used to investigate the biological activity of anti-LPS antibodies and other LPS-specific serum components in sera from patients with cystic fibrosis (CF). As a group, sera from 10 CF patients chronically infected with P. aeruginosa did not affect the LPS-induced TNF release, while sera from normal controls inhibited this biological activity. When individual CF patients with or without chronic lung infection are considered, the antibodies appear to either enhance or inhibit the LPS-stimulated TNF release (range: 73-120%), while all antibodies from healthy controls inhibit the activity of LPS (range: 76-97%). Only a weak correlation (rho = 0.491, p = 0.037, n = 19) was found between the antibody titer in ELISA and the biological activity of sera. This new assay is suggested for convenient measurement of interference with cytokine induction from human MNC by patient or therapeutic anti-LPS antibodies and other LPS-specific serum components.

Cystic fibrosis and physical activity: an introduction.

Cystic fibrosis (CF) is the most common autosomal-recessive disease in the white population. Its main symptoms are: recurrent respiratory infections secondary to an abnormally thick bronchial mucous secretion, malnutrition caused by pancreatic insufficiency, and elevated sweat electrolytes. Progressive deterioration of lung functions is the most severe problem, and a premature death is usually due to respiratory failure. A comprehensive, very demanding, time-consuming, and expensive regimen directed to all manifestations of the disease has considerably ameliorated the outcome for these patients. Lately, several reports give evidence that physical activity is an essential part of the CF regimen. The observations reported in this supplement further support this concept. The implications for the individual CF patient and for the CF group are discussed.

Development and use of a serotyping scheme for Pseudomonas cepacia

A method is described for the serological typing of Pseudomonas cepacia. Mice were immunized with each of 39 P. cepacia isolates by intraperitoneal injection of whole cells. Based upon agglutination reactions with homologous and heterologous anti-sera, the P. cepacia isolates were separated into five serotypes, A-E. Large volumes of antisera were obtained by immunization of rabbits with whole cells of each of the five type strains. These antisera were used to type 137 P. cepacia isolates from five geographic locations including consecutive isolates from individual cystic fibrosis patients. Results from these studies indicate that strains related by geographic isolation site demonstrate a tendency toward serological relatedness, and that cystic fibrosis patients tend to be infected by one P. cepacia serotype and remain infected with that same serotype over time.