Use of random amplified polymorphic DNA PCR to examine epidemiology of Stenotrophomonas maltophilia and Achromobacter (Alcaligenes) xylosoxidans from patients with cystic fibrosis

Association between Stenotrophomonas maltophilia and lung function in cystic fibrosis

BACKGROUND

Stenotrophomonas maltophilia (SM) is a Gram-negative non-fermenting bacteria cultured from the sputum of patients with cystic fibrosis (CF). To date, no information is available regarding the effect of this organism on lung function in CF.

METHODS

A cohort study was conducted to assess the effect of SM on lung function among CF patients aged > or =6 years in the CF Foundation National Patient Registry from 1994 to 1999. Repeated measures regression was used to assess the association between SM and lung function.

RESULTS

The cohort consisted of 20 755 patients with median age at entry of 13.8 years and median follow up time of 3.8 years; 2739 patients (13%) were positive at least once for SM and 18 016 (87%) were never positive. After adjusting for sex, height and age, patients with SM had a mean forced expiratory volume in 1 second which was 0.09 l less (95% CI 0.05 to 0.14) than those without SM. The mean rate of decline associated with SM positivity was 0.025 l/year (95% CI 0.012 to 0.037) but, after adjusting for confounders (sex, height, weight, intravenous antibiotic courses, hospital admissions, pancreatic insufficiency, and Pseudomonas aeruginosa and Burkholderia cepacia status), the mean rate of decline decreased to 0.008 l/year (-0.008, 95% CI -0.019 to 0.003).

CONCLUSIONS

Although CF patients with SM have worse lung function at the time of positivity, no association was found between SM and increased rate of decline after controlling for confounders.

Early intervention and prevention of lung disease in cystic fibrosis: a European consensus

In patients with cystic fibrosis (CF), early intervention and prevention of lung disease is of paramount importance. Principles to achieve this aim include early diagnosis of CF, regular monitoring of the clinical status, various hygienic measures to prevent infection and cross-infection, early use of antibiotic courses in patients with recurrent or continuous bacterial colonisation and appropriate use of chest physiotherapy.

Identification of genomic groups in the genusStenotrophomonasusinggyrBRFLP analysis

Stenotrophomonas maltophilia isolates have been recovered from various clinical samples, including the respiratory tract of cystic fibrosis (CF) patients, but this organism is also widespread in nature. Previously it has been shown that there is a considerable genomic diversity within S. maltophilia. The aims of our study were to determine the taxonomic resolution of restriction fragment length polymorphism (RFLP) analysis of the polymerase chain reaction-amplified gyrB gene for the genus Stenotrophomonas. Subsequently, we wanted to use this technique to screen a set of S. maltophilia isolates (with emphasis on a specific subset, isolates recovered from CF patients), to assess the genomic diversity within this group. In this study we investigated 191 Stenotrophomonas sp. isolates (including 40 isolates recovered from CF patients) by means of gyrB RFLP. The taxonomic resolution of gyrB RFLP, and hence its potential as an identification tool, was confirmed by comparison with results from published and novel DNA-DNA hybridisation experiments. Our data also indicate that the majority of CF isolates grouped in two clusters. This may indicate that isolates from specific genomic groups have an increased potential for colonisation of the respiratory tract of CF patients.

Infection control in cystic fibrosis

Over the past 20 years there has been a greater interest in infection control in cystic fibrosis (CF) as patient-to-patient transmission of pathogens has been increasingly demonstrated in this unique patient population. The CF Foundation sponsored a consensus conference to craft recommendations for infection control practices for CF care providers. This review provides a summary of the literature addressing infection control in CF. Burkholderia cepacia complex, Pseudomonas aeruginosa, and Staphylococcus aureus have all been shown to spread between patients with CF. Standard precautions, transmission-based precautions including contact and droplet precautions, appropriate hand hygiene for health care workers, patients, and their families, and care of respiratory tract equipment to prevent the transmission of infectious agents serve as the foundations of infection control and prevent the acquisition of potential pathogens by patients with CF. The respiratory secretions of all CF patients potentially harbor clinically and epidemiologically important microorganisms, even if they have not yet been detected in cultures from the respiratory tract. CF patients should be educated to contain their secretions and maintain a distance of >3 ft from other CF patients to avoid the transmission of potential pathogens, even if culture results are unavailable or negative. To prevent the acquisition of pathogens from respiratory therapy equipment used in health care settings as well as in the home, such equipment should be cleaned and disinfected. It will be critical to measure the dissemination, implementation, and potential impact of these guidelines to monitor changes in practice and reduction in infections.

Molecular epidemiology in the public health and hospital environments

The increasing speed and ease of genomic sequencing coupled with available funding to sequence multiple, unrelated strains of the same species will lead inevitably to the identification of candidate genes that can be used as molecular typing tools (MLST, SLST, microarray approach). However, it is important to note that even the most sophisticated typing tool should never replace a full epidemiologic investigation in which all available information is taken into account. Nevertheless, the typing methods discussed in this article and those yet to be developed have significantly improved the quality of health care worldwide.

Pathophysiology and management of pulmonary infections in cystic fibrosis

This comprehensive State of the Art review summarizes the current published knowledge base regarding the pathophysiology and microbiology of pulmonary disease in cystic fibrosis (CF). The molecular basis of CF lung disease including the impact of defective cystic fibrosis transmembrane regulator (CFTR) protein function on airway physiology, mucociliary clearance, and establishment of Pseudomonas aeruginosa infection is described. An extensive review of the microbiology of CF lung disease with particular reference to infection with P. aeruginosa is provided. Other pathogens commonly associated with CF lung disease including Staphylococcal aureus, Burkholderia cepacia, Stenotrophomonas maltophilia, Achromobacter xylosoxidans and atypical mycobacteria are also described. Clinical presentation and assessment of CF lung disease including diagnostic microbiology and other measures of pulmonary health are reviewed. Current recommendations for management of CF lung disease are provided. An extensive review of antipseudomonal therapies in the settings of treatment for early P. aeruginosa infection, maintenance for patients with chronic P. aeruginosa infection, and treatment of exacerbation in pulmonary symptoms, as well as antibiotic therapies for other CF respiratory pathogens, are included. In addition, the article discusses infection control policies, therapies to optimize airway clearance and reduce inflammation, and potential future therapies.

Traitement anti-infectieux vis-a-vis du Pseudomonas aeruginosa et autres bacilles a gram negatif dans la mucoviscidose

In cystic fibrosis patients, bronchial infection with Pseudomonas aeruginosa (PA) is frequent, occurring often early in life. It becomes chronic because of a particular relationship between bacteria and host. Intensive antibiotic treatment often permits a transient eradication. When infection becomes chronic, antibiotics must be prescribed in a way to afford resistance. Efficacy of nebulized antibiotics is now recognized. Problems persist. Because of the difficulty to eradicate PA, new strategies may consist in diminishing the pathogenicity of PA, by inhibiting adhesion and virulence factors' production.

Fimbriae and adherence of Stenotrophomonas maltophilia to epithelial cells and to abiotic surfaces

Stenotrophomonas maltophilia is an emerging nosocomial bacterial pathogen associated with several infectious diseases and opportunistic infections, especially in immunocompromised patients. These bacteria adhere avidly to medical implants and catheters forming a biofilm that confers natural protection against host immune defences and different antimicrobial agents. The nature of the bacterial surface factors involved in biofilm formation on inert surfaces and in adherence of S. maltophilia to epithelial cells is largely unknown. In this study, we identified and characterized fimbrial structures produced by S. maltophilia grown at 37 degrees C. The S. maltophilia fimbriae 1 (SMF-1) are composed of a 17 kDa fimbrin subunit which shares significant similarities with the N-terminal amino acid sequences of several fimbrial adhesins (G, F17, K99 and 20K) found in Escherichia coli pathogenic strains and the CupA fimbriae of Pseudomonas aeruginosa. All of the clinical S. maltophilia isolates tested produced the 17 kDa fimbrin. Antibodies raised against SMF-1 fimbriae inhibited the agglutination of animal erythrocytes, adherence to HEp-2 cells and biofilm formation by S. maltophilia. High resolution electron microscopy provided evidence of the presence of fimbriae acting as bridges between bacteria adhering to inert surfaces or to cultured epithelial cells. This is the first characterization of fimbriae in this genus. We provide compelling data suggesting that the SMF-1 fimbriae are involved in haemagglutination, biofilm formation and adherence to cultured mammalian cells.

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.

Significant microbiological effect of inhaled tobramycin in young children with cystic fibrosis

We conducted a double-blind, placebo-controlled, multicenter, randomized trial to test the hypothesis that 300 mg of tobramycin solution for inhalation administered twice daily for 28 days would be safe and result in a profound decrease in Pseudomonas aeruginosa (Pa) density from the lower airway of young children with cystic fibrosis. Ninety-eight subjects were to be randomized; however, the trial was stopped early because of evidence of a significant microbiological treatment effect. Twenty-one children under age 6 years were randomized (8 active; 13 placebo) and underwent bronchoalveolar lavage at baseline and on Day 28. There was a significant difference between treatment groups in the reduction in Pa density; no Pa was detected on Day 28 in 8 of 8 active group patients compared with 1 of 13 placebo group patients. We observed no differences between treatment groups for clinical indices, markers of inflammation, or incidence of adverse events. No abnormalities in serum creatinine or audiometry and no episodes of significant bronchospasm were observed in association with active treatment. We conclude that 28 days of tobramycin solution for inhalation of 300 mg twice daily is safe and effective for significant reduction of lower airway Pa density in young children with cystic fibrosis.

Detecting Stenotrophomonas maltophilia does not reduce survival of patients with cystic fibrosis

Stenotrophomonas maltophilia is a gram-negative bacterium that has been cultured with increasing prevalence from the sputum of patients with cystic fibrosis (CF). We conducted a cohort study, using the Cystic Fibrosis Foundation Registry, to assess the effect of S. maltophilia on survival. We studied all patients in this registry from 1991 to 1997 who were older than 6 years of age, were S. maltophilia negative in the first year of enrollment, and had their CF diagnosed before the age of 45 years (n = 19,255 in the study). We compared patients who acquired S. maltophilia with those who did not, using survival analysis. A total of 1,673 (8.7%) had at least one sputum sample positive for S. maltophilia. Compared with patients without S. maltophilia, those patients positive for S. maltophilia had the following baseline characteristics before detection: lower FEV(1) % pred (p < 0.001); older (p = 0.001); more likely to be female (p = 0.003); and more pulmonary exacerbations (p < 0.001), outpatient visits (p < 0.002), and total hospitalizations (p < 0.001). After controlling for differences in severity of disease and coinfection with Pseudomonas aeruginosa, the hazard ratio associated with S. maltophilia detection was 0.89 (95% confidence interval, 0.75-1.05). Although patients with CF who acquire S. maltophilia have more advanced disease than those who do not acquire this organism, detection does not independently affect short-term survival (3 years).

Factors affecting the incidence of Stenotrophomonas maltophilia isolation in cystic fibrosis

STUDY OBJECTIVES

To identify factors predisposing cystic fibrosis (CF) patients to Stenotrophomonas maltophilia infection and to determine whether coinfection with S maltophilia affects the clinical response to therapy with tobramycin solution for inhalation (TSI), 300 mg bid.

DESIGN

Retrospective review of data collected from two identical, 6-month, randomized, placebo-controlled trials.

SETTING

Sixty-nine CF centers in the United States.

INTERVENTIONS

Active drug administration of 300 mg TSI.

PATIENTS

Five hundred twenty CF patients with chronic Pseudomonas aeruginosa endobronchial infections.

MEASUREMENTS AND RESULTS

A logistic regression analysis identified factors contributing to increased S maltophilia isolation frequency. In this multivariate analysis, the only significant predictors of S maltophilia isolation during the last month of the trial were the concomitant use of oral quinolones (primarily ciprofloxacin; p = 0.0015) and S maltophilia isolation prior to treatment (p < 0.0001). Treatment group, gender, age, use of systemic or inhaled steroids, use of oral sulfonamide, IV cephalosporins, or penicillin antibiotics, baseline FEV(1) percent predicted, and pretreatment Aspergillus isolation were not significant predictors of subsequent S maltophilia infection. In addition, S maltophilia-positive culture frequency was compared to the change in pulmonary function. Patients who either never had culture results positive for S maltophilia or who were positive at <25% of observations had greater clinical response to TSI at the final study visit compared to patients who were positive at > or = 25% of observations.

CONCLUSIONS

TSI therapy did not result in a greater risk for isolation of S maltophilia than standard care alone. In contrast, oral quinolone antibiotic use during the trial was associated with a 2.7-fold increased risk of having a culture positive for S maltophilia (p = 0.0015). The use of TSI to suppress P aeruginosa resulted in improved lung function, regardless of S maltophilia culture frequency. However, improvement was not as great among patients who were persistently coinfected with S maltophilia.

Ribosomal DNA-directed PCR for identification of Achromobacter (Alcaligenes) xylosoxidans recovered from sputum samples from cystic fibrosis patients

The opportunistic human pathogen Achromobacter (Alcaligenes) xylosoxidans has been recovered with increasing frequency from respiratory tract culture of persons with cystic fibrosis (CF). However, confusion of this species with other closely related respiratory pathogens has limited studies to better elucidate its epidemiology, natural history, and pathogenic role in CF. Misidentification of A. xylosoxidans as Burkholderia cepacia complex is especially problematic and presents a challenge to effective infection control in CF. To address the problem of accurate identification of A. xylosoxidans, we developed a PCR assay based on a 16S ribosomal DNA sequence. In an analysis of 149 isolates that included 47 A. xylosoxidans and several related glucose-nonfermenting species recovered from CF sputum, the sensitivity and specificity of this PCR assay were determined to be 100 and 97%, respectively. The availability of this assay will enhance identification of A. xylosoxidans, thereby facilitating study of the pathogenic role of this species and improving infection control efforts in CF.