Pseudomonas cepacia in lung transplant recipients with cystic fibrosis

Post-transplant outcomes among cystic fibrosis patients undergoing lung transplantation colonized by Burkholderia: A single center cohort study

BACKGROUND

Prior infection with Burkholderia cepacia complex (BCC) has been associated with poorer outcomes after lung transplantation, posing an important dilemma for cystic fibrosis (CF). Although current guidelines consider BCC infection to be a relative contraindication, some centers continue to offer lung transplantation to BCC-infected CF patients.

METHODS

We conducted a retrospective cohort study which included all consecutive CF-LTR between 2000 and 2019 to compare the postoperative survival of BCC-infected CF lung transplant recipients (CF-LTR) to BCC-uninfected patients. We used a Kaplan-Meier analysis to compare survival of BCC-infected to BCC-uninfected CF-LTR and fitted a multivariable Cox model, adjusted for age, sex, BMI and year of transplantation as potential confounders. As an exploratory analysis, Kaplan-Meier curves were also stratified by the presence of BCC and urgency of transplantation.

RESULTS

A total of 205 patients were included with a mean age of 30.5 years. Seventeen patients (8%) were infected with BCC prior to LT. Patients were infected with the following species: B. multivorans5, B. vietnamiensis3, combined B. multivorans and B. vietnamiensis3 and others4. None of the patients were infected with B. cenocepacia. Three patients were infected with B. gladioli. One-year survival was 91.7% (188/205) for the entire cohort, 82.4% (14/17) among BCC-infected CF-LTR, and 92.5% (173/188) among BCC uninfected CF-LTR (crude HR = 2.19; 95%CI 0.99-4.85; p = 0.05). In the multivariable model, presence of BCC was not significantly associated with worse survival (adjusted HR 1.89; 95%CI 0.85-4.24; p = 0.12). In the stratified analysis for both presence of BCC and urgency of transplantation, urgency of transplantation among BCC-infected CF-LTR appeared to be associated with poorer outcome (p = 0.003 across the 4 subgroups).

CONCLUSION

Our results suggest that non-cenocepacia BCC-infected CF-LTR have comparable survival rate to BCC-uninfected CF-LTR.

Multiresistant organisms: bacteria and beyond

PURPOSE OF REVIEW

Infections with multiresistant organisms are an emerging problem, cause early mortality post lung transplantation and are sometimes associated with graft dysfunction. Frequently they raise questions about the selection of lung transplant candidates and therapeutic management post lung transplantation. There are no guidelines and management must be individualized. This review summarizes the available therapeutic options in cases of multidrug-resistant (MDR) organisms and outcomes after lung transplant.

RECENT FINDINGS

Improvements in diagnosis, new and more effective drugs and the experience gained in the management of these infections in lung transplantation, lead to a more optimistic horizon than that found a decade ago.

SUMMARY

Update on the management of Burkholderia cepacia complex, Mycobacterium abscessus complex, Aspergillus spp., Scedosporium spp. and Lomentospora prolificans infections. This review clarifies current posttransplant outcomes and adds a little hope in these scenarios.

Interactions Between Pathogenic Burkholderia and the Complement System: A Review of Potential Immune Evasion Mechanisms

The genus Burkholderia contains over 80 different Gram-negative species including both plant and human pathogens, the latter of which can be classified into one of two groups: the Burkholderia pseudomallei complex (Bpc) or the Burkholderia cepacia complex (Bcc). Bpc pathogens Burkholderia pseudomallei and Burkholderia mallei are highly virulent, and both have considerable potential for use as Tier 1 bioterrorism agents; thus there is great interest in the development of novel vaccines and therapeutics for the prevention and treatment of these infections. While Bcc pathogens Burkholderia cenocepacia, Burkholderia multivorans, and Burkholderia cepacia are not considered bioterror threats, the incredible impact these infections have on the cystic fibrosis community inspires a similar demand for vaccines and therapeutics for the prevention and treatment of these infections as well. Understanding how these pathogens interact with and evade the host immune system will help uncover novel therapeutic targets within these organisms. Given the important role of the complement system in the clearance of bacterial pathogens, this arm of the immune response must be efficiently evaded for successful infection to occur. In this review, we will introduce the Burkholderia species to be discussed, followed by a summary of the complement system and known mechanisms by which pathogens interact with this critical system to evade clearance within the host. We will conclude with a review of literature relating to the interactions between the herein discussed Burkholderia species and the host complement system, with the goal of highlighting areas in this field that warrant further investigation.

The Impact of Resistant Bacterial Pathogens including Pseudomonas aeruginosa and Burkholderia on Lung Transplant Outcomes

Pseudomonas and Burkholderia are gram-negative organisms that achieve colonization within the lungs of patients with cystic fibrosis, and are associated with accelerated pulmonary function decline. Multidrug resistance is a hallmark of these organisms, which makes eradication efforts difficult. Furthermore, the literature has outlined increased morbidity and mortality for lung transplant (LTx) recipients infected with these bacterial genera. Indeed, many treatment centers have considered Burkholderia cepacia infection an absolute contraindication to LTx. Ongoing research has delineated different species within the B. cepacia complex (BCC), with significantly varied morbidity and survival profiles. This review considers the current evidence for LTx outcomes between the different subspecies encompassed within these genera as well as prophylactic and management options. The availability of meta-genomic tools will make differentiation between species within these groups easier in the future, and will allow more evidence-based decisions to be made regarding suitability of candidates colonized with these resistant bacteria for LTx. This review suggests that based on the current evidence, not all species of BCC should be considered contraindications to LTx, going forward.

Interactions Between Pathogenic Burkholderia and the Complement System: A Review of Potential Immune Evasion Mechanisms

The genus Burkholderia contains over 80 different Gram-negative species including both plant and human pathogens, the latter of which can be classified into one of two groups: the Burkholderia pseudomallei complex (Bpc) or the Burkholderia cepacia complex (Bcc). Bpc pathogens Burkholderia pseudomallei and Burkholderia mallei are highly virulent, and both have considerable potential for use as Tier 1 bioterrorism agents; thus there is great interest in the development of novel vaccines and therapeutics for the prevention and treatment of these infections. While Bcc pathogens Burkholderia cenocepacia, Burkholderia multivorans, and Burkholderia cepacia are not considered bioterror threats, the incredible impact these infections have on the cystic fibrosis community inspires a similar demand for vaccines and therapeutics for the prevention and treatment of these infections as well. Understanding how these pathogens interact with and evade the host immune system will help uncover novel therapeutic targets within these organisms. Given the important role of the complement system in the clearance of bacterial pathogens, this arm of the immune response must be efficiently evaded for successful infection to occur. In this review, we will introduce the Burkholderia species to be discussed, followed by a summary of the complement system and known mechanisms by which pathogens interact with this critical system to evade clearance within the host. We will conclude with a review of literature relating to the interactions between the herein discussed Burkholderia species and the host complement system, with the goal of highlighting areas in this field that warrant further investigation.

Complete genome sequence of sequential Pandoraea apista isolates from the same cystic fibrosis patient supports a model of chronic colonization with in vivo strain evolution over time

Pandoraea apista in the family Burkholderiaceae is an emerging opportunistic pathogen in cystic fibrosis patients. Here, we describe a case from which 3 separate isolates of P. apista were recovered over a 1-year period. Using a combination of first-, second-, and third-generation sequencing technologies, we sequenced and de novo assembled the complete genomes of these 3 P. apista isolates. The genome of P. apista TF81F4 sequenced in this study was 5.58 Mb with a GC% of 62.3%, differed in sequence from other Pandoraea species by >20%, and included a number of previously undescribed loci. Three P. apista isolates cultured over a 12-month period were >99.999% identical by nucleotide, consistent with a model of chronic colonization by a single strain. Over time, the isolates accumulated point mutations, deletions, and insertions in a stepwise fashion, indicating in vivo strain evolution within the cystic fibrosis lung niche.

Lung transplantation for cystic fibrosis: results, indications, complications, and controversies

Survival in patients with cystic fibrosis (CF) has improved dramatically over the past 30 to 40 years, with mean survival now approximately 40 years. Nonetheless, progressive respiratory insufficiency remains the major cause of mortality in CF patients, and lung transplantation (LT) is eventually required. Timing of listing for LT is critical, because up to 25 to 41% of CF patients have died while awaiting LT. Globally, approximately 16.4% of lung transplants are performed in adults with CF. Survival rates for LT recipients with CF are superior to other indications, yet LT is associated with substantial morbidity and mortality (∼50% at 5-year survival rates). Myriad complications of LT include allograft failure (acute or chronic), opportunistic infections, and complications of chronic immunosuppressive medications (including malignancy). Determining which patients are candidates for LT is difficult, and survival benefit remains uncertain. In this review, we discuss when LT should be considered, criteria for identifying candidates, contraindications to LT, results post-LT, and specific complications that may be associated with LT. Infectious complications that may complicate CF (particularly Burkholderia cepacia spp., opportunistic fungi, and nontuberculous mycobacteria) are discussed.

Clinical and in vitro evidence for the antimicrobial therapy in Burkholderia cepacia complex infections

Treatment of infections caused by Burkholderia cepacia complex (Bcc) in cystic fibrosis (CF) patients poses a complex problem. Bcc is multidrug-resistant due to innate and acquired mechanisms of resistance. As CF patients receive multiple courses of antibiotics, susceptibility patterns of strains from CF patients may differ from those noted in strains from non-CF patients. Thus, there was a need for assessing in vitro and clinical data to guide antimicrobial therapy in these patients. A systematic search of literature, followed by extraction and analysis of available information from human and in vitro studies was done. The results of the analysis are used to address various aspects like use of antimicrobials for pulmonary and non-pulmonary infections, use of combination versus monotherapy, early eradication, duration of therapy, route of administration, management of biofilms, development of resistance during therapy, pharmacokinetics-pharmacodynamics correlations, therapy in post-transplant patients and newer drugs in Bcc-infected CF patients.

Risk Factors forBurkholderia cepaciaComplex Bacteremia Among Intensive Care Unit Patients Without Cystic Fibrosis: A Case-Control Study

Background.

TheBurkholderia cepaciacomplex is associated with colonization or disease in patients with cystic fibrosis (CF). For patients without CF, this complex is poorly understood apart from its presence in occasional point source outbreaks.

Objective.

To investigate risk factors forB. cepaciabacteremia in hospitalized, intensive care unit patients without CF.

Methods.

We identified patients with 1 or more blood cultures positive forB. cepaciabetween May 1, 1996, and March 31, 2002, excluding those with CF. Control patients were matched to case patients by ward, duration of hospitalization, and onset date of bacteremia. Matched analyses were used to identify risk factors forB. cepaciabacteremia.

Results.

We enrolled 40 patients withB. cepaciabacteremia into the study. No environmental or other point source forB. cepaciacomplex was identified, although horizontal spread was suspected. Implementation of contact precautions was effective in decreasing the incidence ofB. cepaciabacteremia. We selected 119 matched controls. Age, sex, and race were similar between cases and controls. In multivariable analysis, renal failure that required dialysis, recent abdominal surgery, 2 or more bronchoscopic procedures before detection ofB. cepaciabacteremia, tracheostomy, and presence of a central line before detection ofB. cepaciabacteremia were independently associated with development ofB. cepaciabacteremia, whereas presence of a percutaneous feeding tube was associated with a lower risk of disease.

Conclusions.

B. cepaciacomplex is an important emerging group of nosocomial pathogens in patients with and patients without CF. Nosocomial spread is likely facilitated by cross-transmission, frequent pulmonary procedures, and central venous access. Infection control measures appear useful for limiting the spread of virulent, transmissible clones ofB. cepaciacomplex.

Antimicrobial prophylaxis in solid-organ transplantation

Solid-organ transplantation has become a widely accepted treatment modality for end-stage diseases. With the advent of newer and more potent immunosuppressive regimens, graft survival has improved, but at the expense of an increased risk for the development of infections secondary to bacterial, fungal, viral and parasitic pathogens. Prevention of such infectious complications with effective, well-tolerated and cost-effective antimicrobials would be ideal to improve the outcome of transplant patients. Cytomegalovirus is the most common cause of viral infections. Herpes simplex virus, Varicella-zoster virus, Epstein-Barr virus and others are also significant pathogens. Fungal infections are associated with the highest mortality rates. This review summarizes the most relevant data pertaining to the current understanding of infection prevention for solid-organ transplant recipients.

Comparative metabolic systems analysis of pathogenic Burkholderia

Burkholderia cenocepacia and Burkholderia multivorans are opportunistic drug-resistant pathogens that account for the majority of Burkholderia cepacia complex infections in cystic fibrosis patients and also infect other immunocompromised individuals. While they share similar genetic compositions, B. cenocepacia and B. multivorans exhibit important differences in pathogenesis. We have developed reconciled genome-scale metabolic network reconstructions of B. cenocepacia J2315 and B. multivorans ATCC 17616 in parallel (designated iPY1537 and iJB1411, respectively) to compare metabolic abilities and contextualize genetic differences between species. The reconstructions capture the metabolic functions of the two species and give insight into similarities and differences in their virulence and growth capabilities. The two reconstructions have 1,437 reactions in common, and iPY1537 and iJB1411 have 67 and 36 metabolic reactions unique to each, respectively. After curating the extensive reservoir of metabolic genes in Burkholderia, we identified 6 genes essential to growth that are unique to iPY1513 and 13 genes uniquely essential to iJB1411. The reconstructions were refined and validated by comparing in silico growth predictions to in vitro growth capabilities of B. cenocepacia J2315, B. cenocepacia K56-2, and B. multivorans ATCC 17616 on 104 carbon sources. Overall, we identified functional pathways that indicate B. cenocepacia can produce a wider array of virulence factors compared to B. multivorans, which supports the clinical observation that B. cenocepacia is more virulent than B. multivorans. The reconciled reconstructions provide a framework for generating and testing hypotheses on the metabolic and virulence capabilities of these two related emerging pathogens.

Transmissibility and infection control implications of Burkholderia cepacia in cystic fibrosis

OBJECTIVE

To describe the microbiology and potential virulence factors of Burkholderia cepacia; to discuss the studies that have investigated its mode of transmission among cystic fibrosis patients; and to identify the major risk factors associated with acquisition of this pathogen inside and outside of the hospital environment.

DATA SOURCES

MEDLINE search of the literature published between 1986 and 1997 using the key words/subject words Pseudomonas cepacia, Burkholderia cepacia, cystic fibrosis, infection control and transmissibility, and the bibliography of selected papers.

DATA EXTRACTION

Selected studies examining epidemiology, microbiology, virulence factors and mode of transmission of B cepacia in cystic fibrosis.

DATA SYNTHESIS AND CONCLUSIONS

B cepacia is a multidrug-resistant Gram-negative bacillus that has recently been recognized as a major respiratory pathogen in patients with cystic fibrosis. Colonization by this organism can lead to rapid pulmonary deterioration and premature death. Recent studies based on genomic subtyping techniques have suggested that it can be transmitted from person to person. Close social contact and hospitalization have been identified as risk factors for cross-infection. With the implementation of strict infection control policies such as segregation according to colonization status, the rate of new colonization has substantially decreased in most cystic fibrosis treatment centres.

Successful cessation of transmitting healthcare -- associated infections due to Burkholderia cepacia complex in a neonatal intensive care unit in a Japanese children's hospital

Background

Burkholderia cepacia strains have been known to possess the capability to cause serious infections especially in neonatal intensive care units (NICUs), and their multi-drug resistances become a severe threat in hospital settings. The aim of this investigation was to evaluate the B. cepacia complex infections in the NICU in Nagano Children's Hospital, Azumino 399-8288, Japan, and to report the intervention leading to the successful cessation of the outbreak.

Methodology

The incidence of isolation and antimicrobial susceptibilities of nosocomial Burkholderia cepacia complex strains during a four-year period were retrospectively examined by clinical microbiological records, and by pulsed-field gel electrophoresis analyses along with the bacteriological verification of disinfectant device itself and procedures for its maintenance routinely used in the NICU.

Results

During the period surveyed between 2007 and 2009, only an isolate per respective year of B. cepacia complex was recovered from each neonate in the NICU. However, in 2010, the successive 6 B. cepacia complex isolates were recovered from different hospitalized neonates. Among them, an isolate was originated from peripheral blood of a neonate, apparently giving rise to systemic infection. In addition, the hospitalized neonate with bacteremia due to B. cepacia complex also exhibited positive cultures from repeated catheterized urine samples together with tracheal aspirate secretions. However other 5 isolates were considered as the transients or contaminants having little to do with infections. Moreover, the 5 isolates between July and October in 2010 revealed completely the same electrophoresis patterns by means of pulsed-field gel electrophoresis analyses, strongly indicating that they were infected through the same medical practices, or by transmission of the same contaminant.

Conclusions

A small outbreak due to B. cepacia complex was brought about in the NICU in 2010, which appeared to be associated with the same genomovar of B. cepacia complex. The source or the rout of infection was unknown in spite of the repeated epidemiological investigation. It is noteworthy that no outbreak due to B. cepacia complex was noted in the NICU after extensive surveillance intervention.

Burkholderia cenocepacia phenotypic clonal variation during a 3.5-year colonization in the lungs of a cystic fibrosis patient

Chronic lung infection is the major cause of morbidity and premature mortality in cystic fibrosis (CF) patients. Bacteria of the Burkholderia cepacia complex are the most threatening pathogens in CF, and a better understanding of how these bacteria adapt to the CF airway environment and resist the host defense mechanisms and therapeutically administered antibiotics is crucial. To provide clues to the adaptive strategies adopted by Burkholderia cenocepacia during long-term colonization, we carried out a phenotypic assessment of 11 clonal variants obtained at the major Portuguese CF Center in Lisbon from sputa of the same CF patient during 3.5 years of colonization of the lungs, until the patient's death with cepacia syndrome. Phenotypic characterization included susceptibility assays against different classes of antimicrobials and characterization of cell motility, cell hydrophobicity and zeta potential, colony and cell morphology, fatty acid composition, growth under iron limitation/load conditions, exopolysaccharide production, and size of the biofilms formed. The results suggest the occurrence of clonal expansion during long-term colonization. For a number of the characteristics tested, no isolation time-dependent consistent alteration pattern could be identified. However, the values for antimicrobial susceptibility and swarming motility for the first B. cenocepacia isolate, thought to have initiated the infection, were consistently above those for the clonal variants obtained during the course of infection, and the opposite was found for the zeta potential. The adaptive strategy for long-term colonization, described here for the first time, involved the alteration of membrane fatty acid composition, in particular a reduction of the degree of fatty acid saturation, in the B. cenocepacia variants retrieved, along with the deterioration of pulmonary function and severe oxygen limitation.

Clinical significance of microbial infection and adaptation in cystic fibrosis

A select group of microorganisms inhabit the airways of individuals with cystic fibrosis. Once established within the pulmonary environment in these patients, many of these microbes adapt by altering aspects of their structure and physiology. Some of these microbes and adaptations are associated with more rapid deterioration in lung function and overall clinical status, whereas others appear to have little effect. Here we review current evidence supporting or refuting a role for the different microbes and their adaptations in contributing to poor clinical outcomes in cystic fibrosis.

Pediatric lung transplantation

Lung transplantation is an accepted therapy for selected pediatric patients with severe end-stage vascular or parenchymal lung disease. Collaboration between the patients' primary care physicians, the lung transplant team, patients, and patients' families is essential. The challenges of this treatment include the limited availability of suitable donor organs, the toxicity of immunosuppressive medications needed to prevent rejection, the prevention and treatment of obliterative bronchiolitis, and maximizing growth, development, and quality of life of the recipients. This article describes the current status of pediatric lung transplantation, indications for listing, evaluation of recipient and donor, updates on the operative procedure,graft dysfunction, and the risk factors, outcomes, and future directions.

Lung transplantation for cystic fibrosis

Lung transplantation is a complex, high-risk, potentially life-saving therapy for the end-stage lung disease of cystic fibrosis (CF). The decision to pursue transplantation involves comparing the likelihood of survival with and without transplantation as well as assessing the effect of wait-listing and transplantation on the patient's quality of life. Although recent population-based analyses of the US lung allocation system for the CF population have raised controversies about the survival benefits of transplantation, studies from the United Kingdom and Canada have suggested a definite survival advantage for those receiving transplants. In response to these and other controversies, leaders in transplantation and CF met together in Lansdowne, Virginia, to consider the state of the art in lung transplantation for CF in an international context, focusing on advances in surgical technique, measurement of outcomes, use of prognostic criteria, variations in local control over listing, and prioritization among the United States, Canada, the United Kingdom, and The Netherlands, patient adherence before and after transplantation and other issues in the broader context of lung transplantation. Finally, the conference members carefully considered how efforts to improve outcomes for lung transplantation for CF lung disease might best be studied. This Roundtable seeks to communicate the substance of our discussions.

Survival after lung transplantation of cystic fibrosis patients infected with Burkholderia cepacia complex

Within the Burkholderia cepacia complex (Bcc), B. cenocepacia portends increased mortality compared with other species. We investigated the impact of Bcc infection on mortality and re-infection following lung transplant (LT). Species designation for isolates from Bcc-infected patients was determined using 16S rDNA and recA gene analyses. Of 75 cystic fibrosis patients undergoing LT from September 1992 to August 2002, 59 had no Bcc and 16 had Bcc (including 7 B. cenocepacia) isolated in the year before LT. Of the latter, 87.5% had Bcc recovered after transplantation, and all retained their pretransplant strains. Survival was 97%, 92%, 76% and 63% for noninfected patients; 89%, 89%, 67% and 56% for patients infected with Bcc species other than B. cenocepacia; and 71%, 29%, 29% and 29% for patients with B. cenocepacia (p = 0.014) at 1 month, 1 year, 3 years and 5 years, respectively. Patients infected with B. cenocepacia before transplant were six times more likely to die within 1 year of transplant than those infected with other Bcc species (p = 0.04) and eight times than noninfected patients (p < 0.00005). Following LT, infection with Bcc species other than B. cenocepacia does not significantly impact 5-year survival whereas infection with B. cenocepacia pretransplant is associated with decreased survival.

Advances in Lung Transplantation for Patients Who Have Cystic Fibrosis

Transplantation in patients who have cystic fibrosis (CF) presents important challenges regarding candidate selection and preoperative management, technical obstacles in the perioperative period, the postoperative management of medical comorbidities related to CF, and the psychosocial impact of transplantation. This article outlines some of these challenges and describes recent advances in approaching this endeavor in patients who have CF.

Suppurative mediastinitis secondary to Burkholderia cepacia in a patient with cystic fibrosis

Burkholderia cepacia is an important opportunistic pathogen among patients with cystic fibrosis (CF); it is associated with deterioration of lung function, poor outcome following lung transplantation and increased mortality. Fever, an elevated white blood cell count, weight loss and an often fatal deterioration in pulmonary function characterize a particular clinical course, termed "Cepacia syndrome". The present case report describes a 40-year-old man with CF who developed Cepacia syndrome complicated by suppurative mediastinitis, from which B cepacia was isolated. Despite optimal medical and surgical therapy, this patient succumbed to his illness. Those caring for patients with CF should be aware of this potentially catastrophic complication of B cepacia infection, especially in the setting of Cepacia syndrome.

Identification of Burkholderia cepacia complex pathogens by rapid-cycle PCR with fluorescent hybridization probes

Members of the Burkholderia cepacia complex are important bacterial pathogens in cystic fibrosis (CF) patients. The B. cepacia complex currently consists of nine genetic subgroups (genomovars) of different epidemiological relevance and possibly of different pathogenic potential in humans. In this study, a new approach was developed for the rapid identification of B. cepacia genomovar I, Burkholderia multivorans (genomovar II), Burkholderia cenocepacia (lineage III-A and III-B), Burkholderia stabilis (genomovar IV) and Burkholderia vietnamiensis (genomovar V), which cause the large majority of infections in CF patients. The method was based on the detection of differences in the recA gene sequence by using rapid-cycle PCR and genomovar-specific fluorescence resonance energy transfer (FRET) probes. The genomovar status of all 39 B. cepacia complex strains tested (genomovars I–V) was identified by melting-curve analysis. Each FRET probe produced a specific fluorescence signal only with the respective genomovar, and not with other B. cepacia complex strains and Burkholderia spp. The identification system was easy to handle and revealed B. cepacia complex genomovar I–V status from culture isolates within about 1 h.

Burkholderia cepacia is associated with pulmonary hypertension and increased mortality among cystic fibrosis patients

The aim of the study was to evaluate the impact of Burkholderia cepacia on cardiovascular status and mortality in cystic fibrosis. Seven patients infected with B. cepacia were matched with 31 patients not infected with this organism for gender, age, height, weight, genotype, and percent predicted forced expiratory volume in one second, partial arterial oxygen pressure, and pancreatic sufficiency status. The pulmonary artery systolic pressure, as assessed by transthoracic echocardiography, was significantly higher in patients infected with B. cepacia (61.3 +/- 17.2 mm Hg) than in controls (37.3 +/- 13.9 mm Hg; P = 0.02), and the mean acceleration time was significantly lower (77 +/- 33 ms versus 108 +/- 25 ms; P = 0.02). The 6-month mortality was significantly higher in patients infected with B. cepacia (57% versus 16%; P = 0.02). Six of the seven patients infected with B. cepacia harbored the same ribotype (genomovar II, B. multivorans). Pulmonary hypertension was significantly more frequent in patients infected by B. cepacia and could contribute to the increased mortality rate.

Mortality after pediatric lung transplantation: autopsies vs. clinical impression

Appreciable mortality accompanies pediatric lung and heart-lung transplantation. The objective of this investigation was to compare the clinical impression of causes of death with autopsy findings in all pediatric lung or heart lung transplant recipients who had an autopsy performed between 1985-2002 at the Children's Hospital of Pittsburgh. Medical records and autopsy findings were reviewed. Thirty recipients with autopsies had 33 transplant procedures: heart-lung (16), double lung (14), repeat lung (2), and repeat heart-lung (1). Perioperative deaths occurred in 8 children, most often precipitated by graft dysfunction. Early deaths (2 weeks-1 year) occurred in 12 children resulting from infection. Late deaths (greater than 1 year) occurred in 10 children. Bronchiolitis obliterans complicated by infection was the major cause of death in these recipients. An autopsy confirmed the clinical impression of cause of death in 29/30 and added significant supplemental information in 16 cases. Unsuspected factors contributing to death included donor lung abnormalities, concurrent infection, and cardiovascular disease. Postmortem examination remains a critical component to augment the understanding of causes of death following pediatric thoracic transplantation.

The impact of pan-resistant bacterial pathogens on survival after lung transplantation in cystic fibrosis: results from a single large referral centre

Reported actuarial one-year survival for patients with cystic fibrosis (CF) after lung transplant is 55-91%. Infection is the most common cause of early death. Colonization with Burkholderia cepacia complex is associated with reduced survival and international lung transplant referral guidelines support individual unit assessment policies for patients colonized with other pan-resistant bacteria. We examined local data on survival after transplant for CF to determine the impact of colonization with pan-resistant bacteria. A retrospective review of all CF patients from Royal Prince Alfred Hospital (RPAH), Sydney, who underwent lung transplantation at St Vincent's Hospital, Sydney, 1989-2002, was performed. Sixty-five patients were listed for lung transplantation with 54 (male: female=29:25) receiving transplants. Of the 11 patients (17%) who died on the waiting list, six were colonized with pan-resistant Pseudomonas aeruginosa. Thirty of the 54 transplanted patients had at least one pan-resistant organism before transplant. In 28 this included P. aeruginosa. Overall one-year survival was 92% with a median survival of 67 months. Overall survival for the pan-resistant group (N = 30) was not significantly different to survival in those with sensitive organisms (N = 24) (Logrank chi square = 1.6, P = 0.2). Three patients colonized with B. cepacia complex pre-transplant survive at 11, 40 and 60 months post-transplant. Infection contributed to 11 of the 18 post-transplant deaths, with pre-transplant-acquired bacterial pathogens responsible in two cases. Patients continued to acquire multiresistant bacteria post-transplantation. Lung transplant survival at St Vincent's Hospital for CF adults from RPAH compares favourably with international benchmarks. Importantly, colonization with pan-resistant bacteria pre-transplant did not appear to adversely affect survival post-transplant.

Use of pulsed-field gel electrophoresis in infection control issues concerning Burkholderia cepacia

There was concern that nosocomial person-to-person transmission of Burkholderia cepacia had occurred when two patients with cystic fibrosis shared a bathroom. Pulsed-field gel electrophoresis demonstrated that the two isolates were unrelated. Subsequent testing of 34 stored isolates of B. cepacia demonstrated that no particular clone predominated in our hospital.

Recipient selection

Since international recommendations for lung transplant recipients were made in 1998, newer tools for predicting mortality in patients who have end-stage lung disease have been investigated. This article reviews studies for predicting mortality in obstructive, restrictive, pulmonary vascular, and suppurative/bronchiectatic lung disease. Newer considerations for alternative treatments, postoperative risks, and contraindications are also examined. The article aims to provide more accurate data for selecting patients who will benefit from lung transplantation.

Infection control recommendations for patients with cystic fibrosis: microbiology, important pathogens, and infection control practices to prevent patient-to-patient transmission

Infection Control Recommendations for Patients With Cystic Fibrosis: Microbiology, Important Pathogens, and Infection Control Practices to Prevent Patient-to-Patient Transmissionupdates, expands, and replaces the consensus statement,Microbiology and Infectious Disease in Cystic Fibrosispublished in 1994. This consensus document presents background data and evidence-based recommendations for practices that are intended to decrease the risk of transmission of respiratory pathogens among CF patients from contaminated respiratory therapy equipment or the contaminated environment and thereby reduce the burden of respiratory illness. Included are recommendations applicable in the acute care hospital, ambulatory, home care, and selected non-healthcare settings. The target audience includes all healthcare workers who provide care to CF patients. Antimicrobial management is beyond the scope of this document.

Selection of patients with cystic fibrosis for lung transplantation

Lung transplantation is the most aggressive therapy available for end-stage lung disease from cystic fibrosis (CF). A new predictive survival model of CF uses demographic, FEV1, nutritional, microbiologic, and acute exacerbation data to produce precise estimates of 5-year survival. The model improves the ability to select patients most likely to have survival benefit from transplantation. We discuss potential application of the survival model to four distinct groups of patients with CF: (1) candidates for cadaveric transplantation, (2) potential living donor recipients, (3) patients infected with multiply-resistant organisms such as Burkholderia cepacia, and (4) patients critically ill and dependent on mechanical ventilation. Measuring the impact of transplantation on quality of life remains a difficult task, and further studies are needed to determine whether lung-transplantation-derived survival benefit implies quality-of-life benefit. However, judicious use of the survival model to select patients for transplantation is likely to improve survival outcomes.

Effect of Burkholderia cepacia infection in the clinical course of patients with cystic fibrosis: a pilot study in a Sydney clinic

BACKGROUND

Colonisation with Burkholderia cepacia complex in patients with cystic fibrosis (CF) has been associated with adverse outcomes. The aim of the present study was to determine the actuarial survival of CF patients colonized with B. cepacia and to evaluate the efficacy of the Royal Prince Alfred Hospital segregation policy. A secondary aim was to characterize the specific genomovars and strains of B. cepacia isolated in an Australian clinic.

METHODS

Retrospective review of spirometric and microbiological data on all patients colonized with B. cepacia. Each B. cepacia-colonized subject was matched with three case-control subjects. Phenotype and genomovar typing, random amplified polymorphic DNA strain type and B. cepacia epidemic strain marker analyses were performed. The effect of B. cepacia colonization on transplant-free survival was estimated by Cox's proportional hazards regression using the entire clinic population.

RESULTS

Fifteen patients were colonized with B. cepacia, of whom six (40%) had died from CF-related disease by August 1998, compared with 30 of 173 (17.3%) of the entire clinic population. Cepacia status had a significant adverse effect on survival, with a hazard ratio of 2.16 (95% confidence interval 1.0-4.69; P = 0.05). The outcome was variable in subgroups of B. cepacia.

DISCUSSION

Colonization with B. cepacia had a significant adverse effect on survival within the study population. Genomovar and strain typing contributed usefully in accessing the effectiveness of the hospital's segregation policy in preventing cross-colonization.

Advances in Burkholderia cepacia complex

Burkholderia cepacia is an important opportunistic pathogen in certain compromised hosts, particularly those with either cystic fibrosis (CF) or chronic granulomatous disease. The "family" of bacteria known as B. cepacia is highly heterogeneous and is composed of at least nine discrete species or genomovars, constituting the B. cepacia complex. Bacteria from the B. cepacia complex are particularly virulent in susceptible hosts, often causing necrotising invasive infection and death. Whereas the microbial determinants of virulence in B. cepacia complex are currently not defined, the bacteria appear to have features facilitating survival within host cells. Burkholderia cepacia is highly resistant to antibiotics and to neutrophil-mediated non-oxidative killing; infection should be treated with combination antimicrobial therapy. Burkholderia cepacia can spread from one CF patient to another. Transmission appears to be facilitated by close personal contact and by certain bacterial factors.

Perioperative care of the lung transplant patient

Improvements in the perioperative management of lung transplant recipients have produced a 90% survival in the first 30 days following surgery. Detailed attention to donor organ procurement and preservation of the allograft are important in ensuring an early successful outcome. Early antibacterial administration based on donor or pretransplant cultures and antiviral therapy in CMV-negative recipients assist in avoiding early infectious complications. Development of hypoxemia or hemodynamic instability in the perioperative period requires a rapid, systematic evaluation with attention to mechanical, immunologic, or infectious causes. Nonpulmonary complications are not infrequent in lung transplant recipients.

Psychiatric issues in pulmonary disease

This article has attempted to provide an overview of the clinical literature regarding the psychological issues facing patients with pulmonary disease, depending on when the illness begins in the life span, because different developmental tasks are disrupted. Patients must contend with side effects of medication that may mimic or exacerbate psychiatric disorders. The main drug interactions for psychiatrists to be aware of in this patient population occur between rifampin, or theophylline and psychotropic medications. In lung transplant recipients on cyclosporine therapy, the antidepressant drug nefazadone may cause increased cyclosporine levels. Psychiatrists must be aware of the risks, benefits, and survival statistics; educate patients; and ascertain whether the patient is competent to make medical decisions regarding treatment procedures.

Epidemiology of Burkholderia cepacia complex in patients with cystic fibrosis, Canada

The Burkholderia cepacia complex is an important group of pathogens in patients with cystic fibrosis (CF). Although evidence for patient-to-patient spread is clear, microbial factors facilitating transmission are poorly understood. To identify microbial clones with enhanced transmissibility, we evaluated B. cepacia complex isolates from patients with CF from throughout Canada. A total of 905 isolates from the B. cepacia complex were recovered from 447 patients in 8 of the 10 provinces; 369 (83%) of these patients had genomovar III and 43 (9.6%) had B. multivorans (genomovar II). Infection prevalence differed substantially by region (22% of patients in Ontario vs. 5% in Quebec). Results of typing by random amplified polymorphic DNA analysis or pulsed-field gel electrophoresis indicated that strains of B. cepacia complex from genomovar III are the most potentially transmissible and that the B. cepacia epidemic strain marker is a robust marker for transmissibility.

Lung transplantation for cystic fibrosis patients with Burkholderia cepacia complex. Survival linked to genomovar type

The number of cystic fibrosis (CF) patients undergoing lung transplant has risen over the past decade, because of a clear-cut survival benefit. However, patients with Burkholderia cepacia complex are often excluded from transplantation because of increased mortality. To determine the influence of B. cepacia complex genomovar type on transplant outcome, we undertook a retrospective study in 121 CF patients transplanted at UNC. Twenty-one and three patients, respectively, were infected pre- or postoperatively with B. cepacia complex. All posttransplant acquisitions were successfully treated. However, excess mortality occurred over the first 6 postoperative months in those infected preoperatively with B. cepacia complex compared with those not infected (33% versus 12%, p = 0.01). The 1-, 3-, and 5-yr survival were significantly lower in the B. cepacia complex cohort. Of the patients infected preoperatively, genomovar III patients were at the highest risk of B. cepacia complex-related mortality (5 of 12 versus 0 of 8, one isolate not typed; p = 0.035). Each of the B. cepacia complex-related deaths was caused by a unique genotype as determined by pulsed-field gel electrophoresis. All isolates were negative for the cable pilin gene. These results warrant a multicenter analysis of B. cepacia complex-infected patients with genomovar-typing to confirm that genomovar III patients are at highest risk for post-transplant complications.

Adherence of Burkholderia cepacia to respiratory tract epithelial cells and inhibition with dextrans

Adherence of Burkholderia cepacia to cells of the respiratory tract of patients with cystic fibrosis (CF) appears to be a necessary precondition for colonization and infection. To date, no effective anti-adhesive strategy has been devised for preventing B. cepacia infection in CF patients. It was found in this study that B. cepacia adhered to respiratory epithelial cells both in vitro and in vivo. However, strains with cable-like pili (Cbl) exhibited the typical clump formation on pneumocytes, whereas non-cable piliated strains predominantly showed single-cell adherence. Dextrans (nominally 4000-10000 Da) significantly inhibited adhesion of B. cepacia to A549 pneumocytes. When compared on an equal weight basis, the nominally 10000 Da dextran was most inhibitory. A dose-dependent inhibitory effect (up to 80 mg ml(-1)) was observed for most strains. Dextran exerted less of an anti-adhesive effect on the two Cbl+ strains than on the others which were Cbl-. Dextrans appeared to block the adherence in a non-specific fashion, as shown by the observations that the inhibitory effect was readily reversible and oligosaccharides composed of 2-4 glucose units with the same alpha-1,6 linkage were not inhibitory. The mean molecular masses of dextrans used in this study, as determined by gel filtration and MS, were approximately 10-fold lower than those indicated by the manufacturers. Our data suggest that dextran of nominal molecular mass 4000 Da at a concentration of 40 mg ml(-1) (10 mM according to manufacturer's quoted molecular mass) or more may be useful in patients with CF to prevent colonization and infection with B. cepacia.