Compliance of clinical microbiology laboratories in the United States with current recommendations for processing respiratory tract specimens from patients with cystic fibrosis

Is prolonged incubation required for optimal recovery of Burkholderia cepacia complex in sputum from cystic fibrosis patients? Data versus dogma

Cystic fibrosis (CF) expert groups globally recommend using selective medium for isolation of Burkholderia cepacia complex (BCC) from respiratory specimens of CF patients. However, there is no consensus available for optimal duration of incubation and recommendations are variable. The purpose of our study was to compare the difference in recovery of BCC in CF samples at 48 hours versus 7 days when inoculated on Burkholderia cepacia selective agar. A total of 307 consecutive clinical respiratory specimens from our local CF unit were studied prospectively (August 2017 to December 2017). All specimens were inoculated on Burkholderia cepacia medium, containing polymyxin B, gentamicin and ticarcillin. In our laboratory, these plates are routinely incubated for 48 hours as per the manufacturer's recommendation. However, for this study all plates with no growth at 48 hours were further incubated for total of 7 days at 35°C in O₂. Plates were read daily to look for any growth. Microbial identification was performed using MALDI-TOF Vitek MS (database V3.0). Of the 307 CF respiratory specimens cultured, 177 (58%) were from paediatric and 130 (42%) were from adult patients; 155 (50%) specimens were sputum, 148 (48%) were cough swabs and four (1%) were bronchoalveolar lavage (BAL). All specimens from adults were sputum except one BAL. Thirteen (4%) cultures from eight adult and five paediatric specimens grew BCC. The majority (294, 96%) of specimens had no growth when incubated for 7 days. All 13 positive isolates recovered within 48 hours and there were no additional positive isolates found beyond 48 hours of incubation. We conclude from our analysis that prolonged incubation is not warranted for recovery of BCC in CF specimens if selective medium containing gentamicin and polymyxin is used. By adopting this approach of non-extended incubation, the burden of work on laboratory personnel can be significantly reduced and much faster turnaround time for CF cultures achieved. Our study confirms the results of recently published data on this point and challenges the prevailing dogma of utility of extended incubation for BCC isolation. For devising consensus statements for microbiology laboratories on this issue, CF societies and expert groups should consider reviewing data from the recent studies.

Organization of Patient Management and Fungal Epidemiology in Cystic Fibrosis

The achievement of a better life for cystic fibrosis (CF) patients is mainly caused by a better management and infection control over the last three decades. Herein, we want to summarize the cornerstones for an effective management of CF patients and to give an overview of the knowledge about the fungal epidemiology in this clinical context in Europe. Data from a retrospective analysis encompassing 66,616 samples from 3235 CF patients followed-up in 9 CF centers from different European countries are shown.

Sputum DNA sequencing in cystic fibrosis: non-invasive access to the lung microbiome and to pathogen details

BACKGROUND

Cystic fibrosis (CF) is a life-threatening genetic disorder, characterized by chronic microbial lung infections due to abnormally viscous mucus secretions within airways. The clinical management of CF typically involves regular respiratory-tract cultures in order to identify pathogens and to guide treatment. However, culture-based methods can miss atypical or slow-growing microbes. Furthermore, the isolated microbes are often not classified at the strain level due to limited taxonomic resolution.

RESULTS

Here, we show that untargeted metagenomic sequencing of sputum DNA can provide valuable information beyond the possibilities of culture-based diagnosis. We sequenced the sputum of six CF patients and eleven control samples (including healthy subjects and chronic obstructive pulmonary disease patients) without prior depletion of human DNA or cell size selection, thus obtaining the most unbiased and comprehensive characterization of CF respiratory tract microbes to date. We present detailed descriptions of the CF and healthy lung microbiome, reconstruct near complete pathogen genomes, and confirm that the CF lungs consistently exhibit reduced microbial diversity. Crucially, the obtained genomic sequences enabled a detailed identification of the exact pathogen strain types, when analyzed in conjunction with existing multi-locus sequence typing databases. We also detected putative pathogenicity islands and indicators of antibiotic resistance, in good agreement with independent clinical tests.

CONCLUSIONS

Unbiased sputum metagenomics provides an in-depth profile of the lung pathogen microbiome, which is complementary to and more detailed than standard culture-based reporting. Furthermore, functional and taxonomic features of the dominant pathogens, including antibiotics resistances, can be deduced-supporting accurate and non-invasive clinical diagnosis.

Infection Prevention and Control Guideline for Cystic Fibrosis: 2013 Update

The 2013 Infection Prevention and Control (IP&C) Guideline for Cystic Fibrosis (CF) was commissioned by the CF Foundation as an update of the 2003 Infection Control Guideline for CF. During the past decade, new knowledge and new challenges provided the following rationale to develop updated IP&C strategies for this unique population:

1.The need to integrate relevant recommendations from evidence-based guidelines published since 2003 into IP&C practices for CF. These included guidelines from the Centers for Disease Control and Prevention (CDC)/Healthcare Infection Control Practices Advisory Committee (HICPAC), the World Health Organization (WHO), and key professional societies, including the Infectious Diseases Society of America (IDSA) and the Society for Healthcare Epidemiology of America (SHEA). During the past decade, new evidence has led to a renewed emphasis on source containment of potential pathogens and the role played by the contaminated healthcare environment in the transmission of infectious agents. Furthermore, an increased understanding of the importance of the application of implementation science, monitoring adherence, and feedback principles has been shown to increase the effectiveness of IP&C guideline recommendations.

2.Experience with emerging pathogens in the non-CF population has expanded our understanding of droplet transmission of respiratory pathogens and can inform IP&C strategies for CF. These pathogens include severe acute respiratory syndrome coronavirus and the 2009 influenza A H1N1. Lessons learned about preventing transmission of methicillin-resistantStaphylococcus aureus(MRSA) and multidrug-resistant gram-negative pathogens in non-CF patient populations also can inform IP&C strategies for CF.

The Impact on Genetic Testing of Mutational Patterns of CFTR Gene in Different Clinical Macrocategories of Cystic Fibrosis

More than 2000 sequence variations of the cystic fibrosis transmembrane conductance regulator gene are known. The marked genetic heterogeneity, poor functional characterization of the vast majority of sequence variations, and an uncertain genotype-phenotype relationship complicate the definition of mutational search strategies. We studied the effect of the marked genetic heterogeneity detected in a case series comprising 610 patients of cystic fibrosis (CF), grouped in different clinical macrocategories, on the operative characteristics of the genetic test designed to fully characterize CF patients. The detection rate in each clinical macrocategory and at each mutational step was found to be influenced by genetic heterogeneity. The definition of a single mutational panel that is suitable for all clinical macrocategories proved impossible. Only for classic CF with pancreas insufficiency did a reduced number of mutations yield a detection rate of diagnostic value. All other clinical macrocategories required an extensive genetic search. The search for specific mutational classes appears to be useful only in specific CF clinical forms. A flowchart defining a mutational search that may be adopted for different CF clinical forms, optimized in respect to those already available, is proposed. The findings also have consequences for carrier screening strategies.

[Cystic Fibrosis Cloud database: An information system for storage and management of clinical and microbiological data of cystic fibrosis patients]

The epidemiological and clinical management of cystic fibrosis (CF) patients suffering from acute pulmonary exacerbations or chronic lung infections demands continuous updating of medical and microbiological processes associated with the constant evolution of pathogens during host colonization. In order to monitor the dynamics of these processes, it is essential to have expert systems capable of storing and subsequently extracting the information generated from different studies of the patients and microorganisms isolated from them. In this work we have designed and developed an on-line database based on an information system that allows to store, manage and visualize data from clinical studies and microbiological analysis of bacteria obtained from the respiratory tract of patients suffering from cystic fibrosis. The information system, named Cystic Fibrosis Cloud database is available on the http://servoy.infocomsa.com/cfc_database site and is composed of a main database and a web-based interface, which uses Servoy's product architecture based on Java technology. Although the CFC database system can be implemented as a local program for private use in CF centers, it can also be used, updated and shared by different users who can access the stored information in a systematic, practical and safe manner. The implementation of the CFC database could have a significant impact on the monitoring of respiratory infections, the prevention of exacerbations, the detection of emerging organisms, and the adequacy of control strategies for lung infections in CF patients.

A Genotypic-Oriented View of CFTR Genetics Highlights Specific Mutational Patterns Underlying Clinical Macrocategories of Cystic Fibrosis

Cystic fibrosis (CF) is a monogenic disease caused by mutations of the cystic fibrosis transmembrane conductance regulator (CFTR) gene. The genotype-phenotype relationship in this disease is still unclear, and diagnostic, prognostic and therapeutic challenges persist. We enrolled 610 patients with different forms of CF and studied them from a clinical, biochemical, microbiological and genetic point of view. Overall, there were 125 different mutated alleles (11 with novel mutations and 10 with complex mutations) and 225 genotypes. A strong correlation between mutational patterns at the genotypic level and phenotypic macrocategories emerged. This specificity appears to largely depend on rare and individual mutations, as well as on the varying prevalence of common alleles in different clinical macrocategories. However, 19 genotypes appeared to underlie different clinical forms of the disease. The dissection of the pathway from the CFTR mutated genotype to the clinical phenotype allowed to identify at least two components of the variability usually found in the genotype-phenotype relationship. One component seems to depend on the genetic variation of CFTR, the other component on the cumulative effect of variations in other genes and cellular pathways independent from CFTR. The experimental dissection of the overall biological CFTR pathway appears to be a powerful approach for a better comprehension of the genotype-phenotype relationship. However, a change from an allele-oriented to a genotypic-oriented view of CFTR genetics is mandatory, as well as a better assessment of sources of variability within the CFTR pathway.

European Cystic Fibrosis Society Standards of Care: Framework for the Cystic Fibrosis Centre

A significant increase in life expectancy in successive birth cohorts of people with cystic fibrosis (CF) is a result of more effective treatment for the disease. It is also now widely recognized that outcomes for patients cared for in specialist CF Centres are better than for those who are not. Key to the effectiveness of the specialist CF Centre is the multidisciplinary team (MDT), which should include consultants, clinical nurse specialist, microbiologist, physiotherapist, dietitian, pharmacist, clinical psychologist, social worker, clinical geneticist and allied healthcare professionals, all of whom should be experienced in CF care. Members of the MDT are also expected to keep up to date with developments in CF through continued professional development, attendance at conferences, auditing and involvement in research. Specialists CF Centres should also network with other Centres both nationally and internationally, and feed Centre data to registries in order to further the understanding of the disease. This paper provides a framework for the specialist CF Centre, including the organisation of the Centre and the individual roles of MDT members, as well as highlighting the value of CF organisations and disease registries.

Microbiological diagnostic procedures for respiratory cystic fibrosis samples in Spain: towards standard of care practices

BACKGROUND

The microbiological procedures for cystic fibrosis (CF) samples of 17 participating Spanish centers were examined to verify their compliance with current international and national guidelines and to implement the best standards of care for microbiology practices. A 47-item questionnaire covering different CF microbiology aspects was sent to participant laboratories. Telephone interviews were performed when necessary. Data about samples processing for bacteria, mycobacteria and fungi were collected.

RESULTS

Gene sequencing (71%), MALDI-TOF (59%) or both (94%) were available for most laboratories. Susceptibility testing was performed by automated microdilution systems (94%) and manual diffusion methods (59%). However, a low use of selective media for Staphylococcus aureus (59%) and Burkholderia cepacia complex (71%), and of epidemiological typing methods (41%) was reported.

CONCLUSIONS

Most Spanish laboratories are in agreement with consensus guidelines for the processing of CF respiratory samples, but need to improve in the use of specific selective media and typing methods for epidemiologic studies.

Use of the Cystic Fibrosis Foundation's extensive sputum-culturing protocol for patients without cystic fibrosis: implications for infection control and antimicrobial resistance

The US Cystic Fibrosis Foundation has guidelines for culturing respiratory tract specimens from patients with cystic fibrosis. Pulmonary physicians were surveyed regarding their use of these extensive cystic fibrosis culture protocols for patients without cystic fibrosis. The survey results and a discussion of the implications of these practices are reported.

Assessment of microbiological diagnostic procedures for respiratory specimens from cystic fibrosis patients in German laboratories by use of a questionnaire

Respiratory specimens from cystic fibrosis (CF) patients challenge microbiological laboratories with their complexity of pathogens and atypical variants. We evaluated the diagnostic procedures in German laboratories by use of a questionnaire. Although most laboratories followed guidelines, some of them served only a small number of patients, while others did not use the recommended selective agars to culture the particular CF-relevant species.

Infection control in cystic fibrosis: barriers to implementation and ideas for improvement

PURPOSE OF REVIEW

This review will focus on recent research documenting baseline adherence to infection control recommendations and barriers to their implementation as experienced by multidisciplinary cystic fibrosis (CF) care providers. In addition, controversies regarding optimal infection control will be discussed. Finally, suggestions to improve infection control in CF will be proposed.

RECENT FINDINGS

Compliance with recent guidelines was assessed for clinical microbiology laboratories and for infection control policies at CF care centers in the United States. Unlike earlier reports, the vast majority of laboratories used selective media for Burkholderia cepacia complex and identified all species of nonlactose fermenting Gram-negative bacilli. Fewer used selective media for Staphylococcus aureus or used agar-based susceptibility testing assays for Pseudomonas aeruginosa. Only 103 (65%) of 158 CF care centers provided written infection control policies for review and these were more likely to address inpatient than outpatient settings. Surveys of healthcare professionals showed that access to a copy of the CF infection control guidelines reduced barriers to adherence to selected infection control practices.

SUMMARY

These data suggest that access to national infection control guidelines and written local policies are critically important to improving infection control for CF.

Cystic fibrosis: what to expect now in the early adult years

As a testimony to advances in patient care, more individuals with cystic fibrosis are surviving into their adult years than ever before. The clinical epidemiology of this complex multi-organ disease is evolving and has changed dramatically over the past two to three decades. This article discusses the emergence of chronic disease-related co-morbidities such as CF-related diabetes, chronic kidney disease, bone disease, arthropathy, and depression. It also provides an overview of the many challenges confronted by adult CF care providers.

Genetic diversity of Burkholderia contaminans isolates from cystic fibrosis patients in Argentina

A total of 120 Burkholderia cepacia complex isolates collected during 2004-2010 from 66 patients in two cystic fibrosis reference centers in Argentina were analyzed. Burkholderia contaminans was the species most frequently recovered (57.6%), followed by Burkholderia cenocepacia (15%), a species distribution not reported so far. The recA-PCR-based techniques applied to the B. contaminans isolates revealed that 85% of the population carried the recA-ST-71 allele. Our results showed the utility of BOX-PCR genotyping in analyzing B. contaminans diversity. This approach allowed us to address clonal transmission during an outbreak and the genetic changes occurring in infecting bacteria over the course of chronic infection.

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.

The changing microbial epidemiology in cystic fibrosis

Infection of the airways remains the primary cause of morbidity and mortality in persons with cystic fibrosis (CF). This review describes salient features of the epidemiologies of microbial species that are involved in respiratory tract infection in CF. The apparently expanding spectrum of species causing infection in CF and recent changes in the incidences and prevalences of infection due to specific bacterial, fungal, and viral species are described. The challenges inherent in tracking and interpreting rates of infection in this patient population are discussed.

Pulmonary exacerbations in cystic fibrosis with negative bacterial cultures

BACKGROUND

Pulmonary exacerbations are a major cause of morbidity in cystic fibrosis (CF) and likely contribute to lung function decline. Exacerbations are often associated with characteristic airway bacteria [CF related bacteria (CFRB)]. However, some patients do not have CFRB detected by culture during exacerbations.

OBJECTIVES

We sought to determine the proportion of airway cultures negative for CFRB during pulmonary exacerbations, and to characterize patients who were CFRB-negative versus CFRB-positive.

METHODS

We performed a retrospective study of patients with CF admitted for a pulmonary exacerbation. Patients were classified as CFRB-positive or CFRB-negative based on admission airway cultures. Demographics, clinical presentation, lung function, history of chronic Pseudomonas aeruginosa infection and improvement in lung function with treatment were compared between groups.

MAIN RESULTS

There were 672 admissions for exacerbation involving 211 patients over 5 years. Seventeen percent were classified as CFRB-negative. Forty-one percent of bronchoalveolar lavage (BAL), 32% of throat and 10% of sputum samples were CFRB-negative. Among patients capable of expectorating sputum, the CFRB-negative group was younger, less likely to have chronic P. aeruginosa, had higher lung function and body mass index (BMI), and had a lower systemic inflammatory response on admission compared to those with CFRB-positive cultures. The two groups had similar numbers of patients with three or more signs and symptoms of a pulmonary exacerbation (88% vs. 92%). Both groups returned to baseline lung function following treatment.

CONCLUSIONS

A significant number of patients with CF and pulmonary exacerbation did not have typical CFRB detected by culture. Patients without CFRB still had characteristic signs and symptoms of pulmonary exacerbation and responded to treatment. Understanding the causes of illness in these patients may improve the diagnosis and treatment of pulmonary exacerbations in CF.

Staphylococcus aureus nasal colonization among pediatric cystic fibrosis patients and their household contacts

BACKGROUND

Little is known about the prevalence of Staphylococcus aureus nasal colonization and the epidemiology of methicillin-susceptible and methicillin-resistant S. aureus (MRSA) among cystic fibrosis (CF) patients and their household members.

OBJECTIVES

We sought to determine the epidemiology of S. aureus among children and adolescents with CF and their household members.

METHODS

Three CF centers enrolled case subjects with at least 1 MRSA-positive respiratory tract culture from 2001 to 2006 and control subjects with MRSA-negative cultures. S. aureus isolates from the anterior nares of CF subjects and their household members were assessed for staphylococcal chromosomal cassette (SCC) mec type. Strain similarity was determined by pulsed-field gel electrophoresis.

RESULTS

S. aureus nasal colonization occurred in 52.4% (22/42), 27.0% (17/63), and 25.0% (72/288) of case, control, and household participants, respectively. Case subjects and their contacts were more likely to harbor MRSA in their nares and be from a multipatient CF family. Of 31 MRSA strains, 10 (32.3%) were SCCmec type IVa, associated with community-acquisition. Overall, 27.6% of 98 households had > or =2 members colonized with closely related isolates. Household members were equally likely to be colonized with closely related strains of MRSA (20/31, 65%) versus MSSA (38/80, 48%).

CONCLUSIONS

This study demonstrated that household members of CF children harbor both MSSA and MRSA, including CA-MRSA, and that S. aureus is transmitted within CF households. Carriage of S. aureus by household members of CF children may have implications for infection control and treatment strategies. Future studies should monitor the distribution and virulence of SCCmecA types in patients with CF.

Rapid identification of Burkholderia cepacia complex species including strains of the novel Taxon K, recovered from cystic fibrosis patients by intact cell MALDI-ToF mass spectrometry

Two approaches based on intact cell matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (IC-MALDI-ToF MS) have been evaluated in order to discriminate and identify nine former Burkholderia cepacia complex (Bcc) species, Burkholderia contaminans belonging to the novel Taxon K, Burkholderia gladioli, and the most relevant non-fermentative (NF) Gram-negative rods recovered from cystic fibrosis (CF) sputum cultures. In total, 146 clinical isolates and 26 reference strains were analysed. IC mass spectra were obtained with high reproducibility applying a recently developed inactivation protocol which is based on the extraction of microbial proteins by trifluoroacetic acid (TFA). In a first approach, spectral analysis was carried out by means of a gel-view representation of mass spectra, which turned out to be useful to recognize specific identifying biomarker proteins (SIBPs). A series of prominent mass peaks, mainly assigned to constitutively expressed proteins, were selected as SIBPs for identifications at the genus and species level. Two distinctive mass peaks present in B. contaminans spectra (7501 and 7900 Da) were proposed as SIBPs for the identification of this novel species. A second approach of spectral analysis based on data reduction, feature selection and subsequent hierarchical cluster analysis was used to obtain an objective discrimination of all species analysed. Both complementary modalities of analyzing complex IC-MALDI-ToF MS data open the path towards a rapid, accurate and objective means of routine clinical microbiology diagnosis of pathogens from sputum samples of CF patients.

Barriers to adherence to cystic fibrosis infection control guidelines

BACKGROUND

In 2003, the American Cystic Fibrosis (CF) Foundation published revised, evidence-based guidelines for infection control. We sought to assess potential barriers to adherence to these guidelines experienced by health care professionals (HCPs) caring for CF patients.

METHODS

From April 2004 to December 2005, a knowledge, attitude, and practice survey was administered to HCPs at randomly selected CF centers in the United States to explore potential barriers to adherence to selected guidelines: (1) obtaining quarterly cultures from CF patients, (2) discouraging socialization among CF patients during hospitalization, (3) educating patients and families about hand hygiene, (4) educating patients and families to clean and disinfect home nebulizers, and (5) cleaning the clinic exam rooms between CF patients.

RESULTS

The survey was completed by 528 HCPs from 25 sites (5-50 respondents per site). Only 60% of respondents were aware of the guidelines, but despite awareness, 31-47% were unfamiliar with the specific guidelines. Self-reported adherence was low; only 23-63% of respondents reported practicing the selected guidelines >75% of the time/opportunities. Lack of self-efficacy, that is, confidence in adequately performing the guidelines, was commonly experienced by respondents. Access to a copy of the guidelines was associated with increased agreement with the recommendations and increased self-efficacy.

CONCLUSIONS

Strategies to reduce barriers to adherence to CF infection control guidelines are needed. Strategies could include quality improvement initiatives with enhanced education and skills workshops, sharing successful interventions among CF centers, and linking adherence to improved patient outcomes.

Fourier transform infrared spectroscopy for rapid identification of nonfermenting gram-negative bacteria isolated from sputum samples from cystic fibrosis patients

The accurate and rapid identification of bacteria isolated from the respiratory tract of patients with cystic fibrosis (CF) is critical in epidemiological studies, during intrahospital outbreaks, for patient treatment, and for determination of therapeutic options. While the most common organisms isolated from sputum samples are Pseudomonas aeruginosa, Staphylococcus aureus, and Haemophilus influenzae, in recent decades an increasing fraction of CF patients has been colonized by other nonfermenting (NF) gram-negative rods, such as Burkholderia cepacia complex (BCC) bacteria, Stenotrophomonas maltophilia, Ralstonia pickettii, Acinetobacter spp., and Achromobacter spp. In the present study, we developed a novel strategy for the rapid identification of NF rods based on Fourier transform infrared spectroscopy (FTIR) in combination with artificial neural networks (ANNs). A total of 15 reference strains and 169 clinical isolates of NF gram-negative bacteria recovered from sputum samples from 150 CF patients were used in this study. The clinical isolates were identified according to the guidelines for clinical microbiology practices for respiratory tract specimens from CF patients; and particularly, BCC bacteria were further identified by recA-based PCR followed by restriction fragment length polymorphism analysis with HaeIII, and their identities were confirmed by recA species-specific PCR. In addition, some strains belonging to genera different from BCC were identified by 16S rRNA gene sequencing. A standardized experimental protocol was established, and an FTIR spectral database containing more than 2,000 infrared spectra was created. The ANN identification system consisted of two hierarchical levels. The top-level network allowed the identification of P. aeruginosa, S. maltophilia, Achromobacter xylosoxidans, Acinetobacter spp., R. pickettii, and BCC bacteria with an identification success rate of 98.1%. The second-level network was developed to differentiate the four most clinically relevant species of BCC, B. cepacia, B. multivorans, B. cenocepacia, and B. stabilis (genomovars I to IV, respectively), with a correct identification rate of 93.8%. Our results demonstrate the high degree of reliability and strong potential of ANN-based FTIR spectrum analysis for the rapid identification of NF rods suitable for use in routine clinical microbiology laboratories.

A German external quality survey of diagnostic microbiology of respiratory tract infections in patients with cystic fibrosis

BACKGROUND

The goal of this pilot study was to design an external quality assessment (EQA) scheme for German cystic fibrosis (CF) clinical microbiology laboratories. Therefore, a multicentre study of 18 German CF laboratories was performed to evaluate their proficiency in analyzing CF respiratory secretions.

METHODS

Simulated clinical specimens containing a set of four frequent CF pathogens, namely two Pseudomonas aeruginosa strains differing in morphotype (mucoid versus non-mucoid) and resistotype, one Staphylococcus aureus strain and one Burkholderia multivorans strain, were distributed to each laboratory. Isolation, identification and antimicrobial susceptibility testing (AST) of any bacterial pathogen present and completion of a questionnaire about applied microbiological protocols were requested.

RESULTS

Three of four strains were isolated and identified correctly by almost all laboratories. B. multivorans was once misidentified as Burkholderia cenocepacia. Fourteen laboratories failed to detect the second multidrug resistant P. aeruginosa isolate. AST errors occurred most often for P. aeruginosa 2 followed by B. multivorans, P. aeruginosa 1 and S. aureus. Evaluation of the questionnaires revealed major differences in cultivation and identification techniques applied by the participating laboratories.

CONCLUSIONS

A periodical EQA programme for German CF laboratories and standardized microbiological procedures seem to be necessary to advance diagnostic microbiology employed on CF respiratory tract specimens and may help to improve anti-infective treatment and infection control practices for CF patients.

Update on the epidemiology and management of Staphylococcus aureus, including methicillin-resistant Staphylococcus aureus, in patients with cystic fibrosis

PURPOSE OF REVIEW

Staphylococcus aureus is one of the first and most common pathogens to be isolated from the respiratory tract of patients with cystic fibrosis. The prevalence of respiratory tract colonization/infection with both methicillin-susceptible and methicillin-resistant S. aureus has increased over the past decade. The clinical significance of colonization/infection with these pathogens is variable, leading to numerous therapeutic strategies: primary prophylaxis, eradication, treatment of cystic fiboris pulmonary exacerbations, and treatment of methicillin-resistant S. aureus.

RECENT FINDINGS

Studies have demonstrated increased prevalence of S. aureus in clinical laboratories that use selective media. Additionally, small colony variant S. aureus has been associated with persistent infection, co-infection with Pseudomonas aeruginosa, and frequent courses of antibiotics, but this phenotype may be difficult to identify in clinical laboratories. Increased prevalence of methicillin-resistant S. aureus has led to use of oral and inhaled antibiotics in attempts to eradicate this pathogen; these studies have yielded variable results.

SUMMARY

The epidemiology of S. aureus in cystic fibrosis has changed. Studies are needed to assess the clinical significance of the increased prevalence of both methicillin-susceptible and methicillin-resistant S. aureus, and whether primary prophylaxis or new treatment/eradication protocols are effective.

Infection Control Practice in Cystic Fibrosis Centers

In this article, the authors outline some of the major historical events that signaled the need to better understand mechanisms of infection in cystic fibrosis (CF). The authors discuss general principles of infection control, focusing on issues of particular importance to patients who have CF. The authors also describe the major pathogens associated with the CF airway, provide a review of findings from inpatient and outpatient studies of infection control, and provide an outline of future directions for investigation.

National survey of molecular epidemiology of Staphylococcus aureus colonization in Belgian cystic fibrosis patients

OBJECTIVES

Epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) is poorly defined in cystic fibrosis (CF) patients, and S. aureus detection may be hampered by the presence of small colony variants (SCVs). We conducted a multicentre survey to determine the prevalence of S. aureus and MRSA colonization in Belgian CF patients and characterize the phenotype and clonal distribution of their staphylococcal strains.

METHODS

S. aureus isolated from CF patients attending nine CF centres were collected. Oxacillin resistance was detected by oxacillin agar screen and mecA PCR. Antibiotic susceptibility was tested by microdilution. MRSA strains were genotyped by PFGE and SCCmec typing and compared with hospital-associated MRSA strains.

RESULTS

Laboratories used a diversity of sputum culture procedures, many of which appeared substandard. S. aureus was isolated from 275/627 (44%) CF patients (20% to 72% by centre). The prevalence of SCV colonization was 4%, but SCVs were almost exclusively recovered from patients in two centres performing an SCV search. Phenotypically, 14% of S. aureus isolates were oxacillin-resistant: 79% carried mecA and 19% were SCVs lacking mecA. The mean prevalence of 'true' MRSA colonization was 5% (0% to 17% by centre). By PFGE typing, 67% of CF-associated MRSA were related to five epidemic clones widespread in Belgian hospitals.

CONCLUSIONS

This first survey of S. aureus colonization in the Belgian CF population indicated a diversity in local prevalence rates and in proportion of oxacillin-resistant and SCV phenotypes, probably related to variation in bacteriological methods. These findings underscore the need for standard S. aureus detection methods and MRSA control policies in Belgian CF centres.