Burkholderia cepacia respiratory tract acquisition: epidemiology and molecular characterization of a large nosocomial outbreak

An outbreak of Burkholderia cepacia complex exit site infection among peritoneal dialysis patients caused by contaminated spray dressing

Background

Wound dressing is intended to provide a physical barrier from microorganisms. Spray dressing is convenient and can be applied to wounds of various contours. In July 2020, a cluster of four Burkholderia cepacia complex (BCC) exit site infections was identified among peritoneal dialysis patients in a regional hospital in Hong Kong. In response, our hospital infection control team conducted an epidemiologic investigation.

Methods

We conducted a retrospective cohort study of peritoneal dialysis patients with culture-confirmed BCC exit site infections from January 2011 to July 2020. Outbreak investigations, including case finding, molecular typing and post-outbreak surveillance, were performed.

Discussion

A substantial increase in BCC exit site infections has been observed since 2013, rising from 0.23 in 2012 to 1.09 episodes per 100 patient-year in 2015, with the number of cases in the first half of 2020 already surpassing the total from 2019. The potential source had been traced to a spray dressing introduced to exit site care in December 2012. Burkholderia cepacia complex was isolated from both the unopened and in-use sprays from the same lot. Multilocus sequence typing analysis confirmed their genetic relatedness. The spray dressing was subsequently removed from exit site care. Post-outbreak surveillance over two years showed a marked and sustained decrease in BCC exit site infection.

Conclusion

Water-based spray dressing can be a source of BCC causing wound infections. The use of contaminated spray dressing, especially in chronic wounds with proximity to indwelling catheters, may pose an inherent risk to patients.

Pathogenicity and virulence of Burkholderia pseudomallei

The soil saprophyte, Burkholderia pseudomallei, is the causative agent of melioidosis, a disease endemic in South East Asia and northern Australia. Exposure to B. pseudomallei by either inhalation or inoculation can lead to severe disease. B. pseudomallei rapidly shifts from an environmental organism to an aggressive intracellular pathogen capable of rapidly spreading around the body. The expression of multiple virulence factors at every stage of intracellular infection allows for rapid progression of infection. Following invasion or phagocytosis, B. pseudomallei resists host-cell killing mechanisms in the phagosome, followed by escape using the type III secretion system. Several secreted virulence factors manipulate the host cell, while bacterial cells undergo a shift in energy metabolism allowing for overwhelming intracellular replication. Polymerisation of host cell actin into “actin tails” propels B. pseudomallei to the membranes of host cells where the type VI secretion system fuses host cells into multinucleated giant cells (MNGCs) to facilitate cell-to-cell dissemination. This review describes the various mechanisms used by B. pseudomallei to survive within cells.

Nosocomial Pneumonia in the Mechanically Ventilated Patient

Ventilator-associated pneumonia (VAP) is a common complication occurring in critically ill patients who are mechanically ventilated and is the leading cause of nosocomial infection-related death. Etiologic agents for VAP widely differ based on the population of intensive care unit patients, duration of hospital stay, and prior antimicrobial therapy. VAP due to multidrug-resistant pathogens is associated with the highest morbidity and mortality, likely due to delays in appropriate antimicrobial treatment. International guidelines are currently available to guide diagnostic and therapeutic strategies. VAP can be prevented through various pharmacological and non-pharmacological interventions, which are more effective when grouped as bundles. When VAP is clinically suspected, diagnostic strategies should include early collection of respiratory samples to guide antimicrobial therapy. Empirical treatment should be based on the most likely etiologic microorganisms and antibiotics likely to be active against these microorganisms. Response to therapy should be reassessed after 3 to 5 days and antimicrobials adjusted or de-escalated to reduce the burden of the disease. Finally, considering that drug resistance is increasing worldwide, several novel antibiotics are being tested to efficiently treat VAP in the coming decades.

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.

Epidemiologic Investigation ofBurkholderia cepaciaAcquisition in Two Pediatric Intensive Care Units

Objectives:

To investigate and describe an outbreak ofBurkholderia cepaciain a neonatal intensive care unit (NICU) and a pediatric intensive care unit (PICU), and to report the interventions leading to the cessation of the outbreak.

Design:

We conducted an epidemiologic investigation of an outbreak ofB. cepaciacolonization or infection in two clinical wards during a 35-month period (December 1998 to October 2001).

Setting:

A 500-bed, university hospital-affiliated, tertiary-care pediatric institution in Paris, France, with a 22-bed PICU and 31-bed NICU.

Methods:

Ribotyping was used to determine the genotypes ofB. cepaciaisolates. Procedures for the maintenance and disinfection of respiratory therapy devices were reviewed.

Results:

Thirty-two children were colonized (n = 14) or infected (n = 18) byB. cepaciain 2 wards (28 in the PICU and 4 in the NICU). In the PICU, a single ribotype was found among the isolates obtained from all of the patients except 1, and from the 6 isolates obtained from respiratory therapy devices (ie, heated humidifier water). In the NICU, the isolates obtained from the patients harbored a single ribotype unrelated to that of the epidemic strain isolated in the PICU; no environmental source of infection was found.

Conclusion:

Two different outbreaks appeared to be associated with 2 ribotypes, 1 of which was linked to patient-to-patient transmission via respiratory therapy devices. Complete elimination of the outbreak was achieved only when disposable, sterilizable, or easy-to-disinfect materials were used in the PICU. The source of infection in the NICU was not found.

Outbreak of Burkholderia cepacia in the Adult Intensive Care Unit Traced to Contaminated Indigo-Carmine Dye

We report an unusual cluster of Burkholderia cepacia in patients. Environmental cultures identified indigo-carmine dye used in enteral feeding as the reservoir. Compared with the controls, the cases were significantly more likely to have received tube feedings tinted with this dye. This outbreak was terminated with the removal of the dye from hospital inventory.

Burkholderia cenocepacia bacteremia without respiratory colonization in an adult intensive care unit: epidemiological and molecular investigation of an outbreak

BACKGROUND

To investigate an outbreak of Burkholderia cenocepacia bacteremia. Observational study and chart review in a multidisciplinary adult Intensive Care Unit (ICU) at a tertiary care hospital.

METHODS

Patients' demographic variables, comorbid conditions, ICU admission diagnosis, disease severity and outcome were analyzed. In case-patients, time and possible sources of bacteremia, molecular assays, antimicrobial susceptibility and response to therapy were also recorded.

RESULTS

During a 9-month period, 30 episodes of B. cenocepacia bacteremia were diagnosed in 21 patients. Median time for a positive blood culture was 9 days after admission. None of the case-patients had respiratory colonization prior to onset of bacteremia. Pathogen was susceptible to meropenem, piperacillin/tazobactam, ciprofloxacin and trimethoprim /sulphamethoxazole. Surveillance involved environmental and patient/personnel cultures. All samples were negative for B. cenocepacia. However, extensive assessment revealed lapses in infection control procedures. PFGE molecular typing showed that all isolates were indistinguishable. Prior surgery and septic shock on ICU admission were significantly more frequent among case-patients. These patients needed significantly prolonged mechanical ventilation, central venous catheterization and ICU hospitalization. All patients responded to antimicrobial therapy and the attributed mortality was zero. Complete elimination of the outbreak was achieved only after strict enforcement of infection control policies and ICU disinfection.

CONCLUSION

The outbreak influenced ICU morbidity but it did not affect mortality. Although extensive environmental investigations failed to identify the source of infection, B.cenocepacia disappeared after implementation of control measures. Effective outbreak elimination cannot be limited to offending reservoir removal but needs to extend to efficient infection control practices.

Isolation of Burkholderia cenocepacia J 2315 from non-cystic fibrosis pediatric patients in India

We report for the first time 2 cases of multidrug-resistant Burkholderia cenocepacia J2315 isolated from blood samples of patients without cystic fibrosis from a pediatric unit in a hospital in India. The first patient presented with community-acquired bacteremia, and the second patient was immunocompromised and developed hospital-acquired infection approximately 17 days after admission. The isolates from both patients were multidrug-resistant and strong biofilm producers. Surveillance cultures identified the secondary sources of the infections, but not the primary sources.

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.

Lack of MyD88 protects the immunodeficient host against fatal lung inflammation triggered by the opportunistic bacteria Burkholderia cenocepacia

Burkholderia cenocepacia is an opportunistic pathogen of major concern for cystic fibrosis patients as well as immunocompromised cancer patients and transplant recipients. The mechanisms by which B. cenocepacia triggers a rapid health deterioration of the susceptible host have yet to be characterized. TLR and their key signaling intermediate MyD88 play a central role in the detection of microbial molecular patterns and in the initiation of an effective immune response. We performed a study to better understand the role of TLR-MyD88 signaling in B. cenocepacia-induced pathogenesis in the immunocompromised host, using an experimental murine model. The time-course of several dynamic parameters, including animal survival, bacterial load, and secretion of critical inflammatory mediators, was compared in infected and immunosuppressed wild-type and MyD88(-/-) mice. Notably, when compared with wild-type mice, infected MyD88(-/-) animals displayed significantly reduced levels of inflammatory mediators (including KC, TNF-alpha, IL-6, MIP-2, and G-CSF) in blood and lung airspaces. Moreover, despite a higher transient bacterial load in the lungs, immunosuppressed mice deficient in MyD88 had an unexpected survival advantage. Finally, we showed that this B. cenocepacia-induced life-threatening infection of wild-type mice involved the proinflammatory cytokine TNF-alpha and could be prevented by corticosteroids. Altogether, our findings demonstrate that a MyD88-dependent pathway can critically contribute to a detrimental host inflammatory response that leads to fatal pneumonia.

Therapeutic options for Burkholderia cepacia infections beyond co-trimoxazole: a systematic review of the clinical evidence

Burkholderia cepacia complex (BCC) is an important group of pathogens affecting patients with cystic fibrosis and chronic granulomatous disease as well as immunocompromised and hospitalised patients. Therapeutic options are limited owing to high levels of resistance of the organism, either intrinsic or acquired, to many antimicrobial agents. Co-trimoxazole (trimethoprim/sulfamethoxazole) has been a drug of choice. However, in some cases it cannot be administered because of allergic or hypersensitivity reactions, intolerance or resistance. We systematically searched for relevant publications including clinical data in PubMed and Scopus. The search identified 48 relevant case reports (57 cases) and 8 cohort studies or trials. Nineteen (33.3%) of 57 patients included in the case reports received ceftazidime-based regimens, 14 (73.7%) of whom were cured. Meropenem was administered in seven patients (12.3%), one (14.3%) of whom improved and five (71.4%) were cured. Seven (12.3%) of 57 cases were treated with penicillins, four of which were piperacillin (all had a favourable outcome). Based on the data reported in the eight relevant cohort studies or trials identified, favourable outcomes were observed in 68.4% (26/38) to 100% (16/16) of cases treated with ceftazidime and 66.7% (6/9) of cases treated with meropenem. Also, 9/12 (75%) of patients receiving penicillins improved. Thus, Ceftazidime, meropenem and penicillins, mainly piperacillin, either alone or in combination with other antimicrobial agents, may be considered as alternative options for BCC infections, according to the in vitro antimicrobial susceptibility patterns and clinical results. However, the available clinical data are not sufficient and further clinical experience is required to clarify the appropriateness of these antibiotics for BCC infections.

Moisturizing body milk as a reservoir of Burkholderia cepacia: outbreak of nosocomial infection in a multidisciplinary intensive care unit

Background

An outbreak of severe nosocomial Burkholderia cepacia infections in patients admitted to intensive care unit (ICU), including investigation of the reservoir, is described.

Methods

Over a period of 18 days, isolates of Burkholderia cepacia were recovered from different biological samples from five patients who were admitted to a multidisciplinary 18-bed intensive care unit. Isolation of B. cepacia was associated with bacteraemia in three cases, lower respiratory tract infection in one and urinary tract infection in one. Contact isolation measures were instituted; new samples from the index patients and adjacent patients were collected; and samples of antiseptics, eau de Cologne and moisturizing body milk available in treatment carts at that time were collected and cultured.

Results

B. cepacia was isolated from three samples of the moisturizing body milk that had been applied to the patients. Three new hermetically closed units, from three different batches, were sent for culture; two of these were positive as well. All strains recovered from environmental and biological samples were identified as belonging to the same clone by pulsed-field gel electrophoresis. The cream was withdrawn from all hospitalization units and no new cases of B. cepacia infection developed.

Conclusion

Moisturizing body milk is a potential source of infection. In severely ill patients, the presence of bacteria in cosmetic products, even within accepted limits, may lead to severe life-threatening infections.

An Outbreak of Burkholderia cepacia Associated With Contamination of Albuterol and Nasal Spray

BACKGROUND

Species within the Burkholderia cepacia complex (Bcc) can contaminate medications and disinfectants and cause severe pneumonia in critically ill patients or persons with cystic fibrosis. In March 2004, we investigated a hospital outbreak of Bcc possibly associated with a contaminated nasal spray.

METHODS

We conducted a matched case-control study, environmental sampling, and observations of infection control practices. Case patients had infection or colonization with Bcc, and control patients had sputum culture not yielding Bcc. Isolates from patients and environmental samples were compared by pulsed-field gel electrophoresis (PFGE).

RESULTS

Bcc was recovered from sputum in 18 patients. Compared with matched control patients (n = 18), case patients were more likely to be receiving mechanical ventilation (p = 0.01), to have been hospitalized > 6 days (p = 0.01), and to have received antimicrobial treatment within 7 days before sputum collection (p = 0.03). Bcc was cultured from opened, but not unopened, multidose albuterol bottles, a nebulizer attached to a ventilator, and opened and unopened nasal spray bottles from contaminated lots. PFGE showed that isolates from albuterol samples and from patients were indistinguishable but unrelated to the nasal spray strain. Observations revealed improper aseptic techniques during respiratory therapy procedures and inadequate nebulizer cleaning.

CONCLUSIONS

Despite a temporal association with use of a contaminated nasal spray, this outbreak was caused by extrinsic contamination of multidose albuterol used for nebulization treatments and lack of adherence to infection control precautions. Implementation and re-enforcement of infection control measures successfully terminated the outbreak.

Sustained endemicity of Burkholderia cepacia complex in a pediatric institution, associated with contaminated ultrasound gel

OBJECTIVE

To determine whether contaminated ultrasound gel is the source of intermittent outbreaks of nosocomial infection due to Burkholderia cepacia complex in patients without cystic fibrosis since 1992.

DESIGN

A prospective clinical and in vitro study of all in-use bottles of ultrasound gel, as well as a retrospective analysis of archived bacterial strains, were performed. Handling of gel for clinical purposes throughout the hospital was evaluated. Gel and archived clinical isolates of B. cepacia complex were speciated to genomovar level and characterized by pulsed-field gel electrophoresis, and the pulsed-field gel electrophoresis patterns were compared.

SETTING

The Hospital for Sick Children, a 300-bed, tertiary care, pediatric academic health sciences center in Toronto, Canada.

PATIENTS

All patients without cystic fibrosis from whom B. cepacia complex was recovered at the Hospital for Sick Children since 1992.

RESULTS

No standardized protocol for storage or handling of ultrasound gel was found. Gel from 39% of bottles grew either B. cepacia (genomovar I) or Burkholderia stabilis (genomovar IV). These isolates had pulsed-field gel electrophoresis patterns identical to 2 of the 7 clinical pulsed-field gel electrophoresis types that are responsible for 88% of clinical isolates.

CONCLUSIONS

Contaminated ultrasound gel contributed to nosocomial infection due to B. cepacia complex in this institution over the course of 10 years. Suggested guidelines for the handling of ultrasound gel are provided.

Two novel clinical presentations of Burkholderia cepacia infection

We report two cases of multidrug-resistant Burkholderia cepacia (B. cepacia genomovar I) and Burkholderia multivorans causing multiple liver abscesses in a patient with bronchial asthma (case 1) and peritonitis in a patient with cirrhosis and hepatitis C virus disease (case 2), respectively. Both patients were treated successfully.

Outbreak of Burkholderia cepacia bacteremia in a pediatric hospital due to contamination of lipid emulsion stoppers

We describe a 7-month outbreak of nosocomial Burkholderia cepacia bacteremia involving eight children in a pediatric hospital and the results of epidemiological investigations. A B. cepacia strain genotypically identical to the blood isolates was recovered from the upper surface of capped rubber stoppers of bottles of a commercial lipid emulsion used for parenteral nutrition.

Identification of Burkholderia cenocepacia genes required for bacterial survival in vivo

Burkholderia cenocepacia (formerly Burkholderia cepacia complex genomovar III) causes chronic lung infections in patients with cystic fibrosis. In this work, we used a modified signature-tagged mutagenesis (STM) strategy for the isolation of B. cenocepacia mutants that cannot survive in vivo. Thirty-seven specialized plasposons, each carrying a unique oligonucleotide tag signature, were constructed and used to examine the survival of 2,627 B. cenocepacia transposon mutants, arranged in pools of 37 unique mutants, after a 10-day lung infection in rats by using the agar bead model. The recovered mutants were screened by real-time PCR, resulting in the identification of 260 mutants which presumably did not survive within the lungs. These mutants were repooled into smaller pools, and the infections were repeated. After a second screen, we isolated 102 mutants unable to survive in the rat model. The location of the transposon in each of these mutants was mapped within the B. cenocepacia chromosomes. We identified mutations in genes involved in cellular metabolism, global regulation, DNA replication and repair, and those encoding bacterial surface structures, including transmembrane proteins and cell surface polysaccharides. Also, we found 18 genes of unknown function, which are conserved in other bacteria. A subset of 12 representative mutants that were individually examined using the rat model in competition with the wild-type strain displayed reduced survival, confirming the predictive value of our STM screen. This study provides a blueprint to investigate at the molecular level the basis for survival and persistence of B. cenocepacia within the airways.

Épidémie nosocomiale à Burkholderia cepacia dans une unité de réanimation infantile

BACKGROUND

We report an outbreak of Burkholderia cepacia respiratory tract infection and colonization in an intensive pediatric care unit.P PATIENTS AND METHODS: Between February and December 1999, B. cepacia was isolated from five children hospitalized in this unit. We reviewed the charts of the patients, evaluated the antiseptics use and the disinfection practices for reusable patient care equipment. An environmental study was conducted and comparison of B. cepacia was performed with genotypic method (RAPD).

RESULTS

All patients were mechanically ventilated and had received large spectrum antibiotics. The disinfection procedure for reusable equipment was not respected and some single-dose of antiseptics solutions were used for several patients. B. cepacia was not found in 34 environmental samples. The RAPD assay revealed that all five isolates had identical DNA profiles.

CONCLUSION

Despite the investigation the source of the B. cepacia clone in this nosocomial outbreak remained unknown, but antiseptics use and disinfection practices were revised. No new B. cepacia infections were identified after control measures were implemented.

Burkholderia cepacia complex in cystic fibrosis and non-cystic fibrosis patients: identification of a cluster of epidemic lineages

This study was performed in order to compare Burkholderia cepacia complex strains from cystic fibrosis (CF) and non-CF patients at the genomovar, genetic and epidemiological levels. A total of 92 B. cepacia respiratory tract isolates were obtained from patients attending the following CF centres: Catania and Palermo, Sicily; Gualdo Tadino, Central Italy, and Milan, Northern Italy. A total of 23 B. cepacia isolates were obtained from blood, surgical wound, and intravenous catheter sources of patients without CF, hospitalized in Catania and Varese, Northern Italy. Genomovar status identification, clonality and genetic relatedness determination, antibiotic susceptibility pattern determination and electron microscopy were performed. Transmission of infection was shown in both CF and non-CF patients by identifying clonality of responsible strains. In total 13 clones were involved in cross-transmission episodes. No outbreak was described involving both CF and non-CF patients. The present study indicates the existence of a distinct cluster of strains responsible for epidemics in CF and non-CF patients, based on their genetic relatedness, distinct from strains associated with no or negligible transmissibility. This result suggests that transmissibility is not only associated with a specific genomovar in CF patients, but also with a group of genetically related lineages in CF and non-CF patients. A key role is shown for both segregation measures and careful surveillance of infection, based on selective culture, molecular identification and epidemiological characterization of individual isolates.

Outbreak of burkholderia cepacia in the adult intensive care unit traced to contaminated indigo-carmine dye

We report an unusual cluster of Burkholderia cepacia in patients. Environmental cultures identified indigo-carmine dye used in enteral feeding as the reservoir. Compared with the controls, the cases were significantly more likely to have received tube feedings tinted with this dye. This outbreak was terminated with the removal of the dye from hospital inventory.

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.

Burkholderia cepacia complex: a contraindication to lung transplantation in cystic fibrosis?

Previous studies have indicated that pulmonary infection with Burkholderia cepacia is associated with poor clinical outcome after lung transplantation in cystic fibrosis (CF). Many treatment centers consider B. cepacia infection an absolute contraindication to lung transplantation. However, the B. cepacia complex actually consists of several closely related bacterial species. Although each of these has been isolated from CF sputum culture, certain species are much more frequently recovered than others, and it is not yet clear whether all species have the same potential for virulence in CF. Additional study is needed to better define the relative risks associated with each species of the B. cepacia complex.

Burkholderia cepacia lower respiratory tract infection associated with exposure to a respiratory therapist

OBJECTIVE

To investigate and control a nosocomial outbreak of Burkholderia cepacia lower respiratory tract infection.

DESIGN

Outbreak investigation and case-control study.

SETTING

A 260-bed community hospital.

PATIENTS

Participants were mechanically ventilated intensive care patients without cystic fibrosis. A case was defined as a hospitalized patient with a sputum culture positive for B. cepacia between January 1 and November 6, 1998.

METHODS

Respiratory therapy infection control policies and practices were reviewed; laboratory and environmental studies and a retrospective case-control study were conducted. Case-patients were matched with control-patients on age, gender, diagnosis, and type of intensive care unit.

RESULTS

Nine case-patients were identified; B. cepacia likely caused pneumonia in seven and colonization in two. Two respiratory therapy practices probably contributed to the transmission of B. cepacia: multidose albuterol vials were used among several patients, and nebulizer assemblies often were not dried between uses. B. cepacia was grown from cultures of three previously opened multidose vials; pulsed-field gel electrophoresis patterns of B. cepacia from seven case-patients and two multidose vials were indistinguishable. Case-patients had longer durations of heated humidified mechanical ventilation (mean, 9.8 days vs 4.4 days; P=.03) and were more likely to have exposure to one particular respiratory therapist than controls (odds ratio, undefined; 95% confidence interval, 4.7-infinity; P=.001). The association with the respiratory therapist, a temporary employee, persisted after controlling for duration of heated humidified ventilation. No new B. cepacia infections were identified after control measures were implemented.

CONCLUSIONS

B. cepacia probably was transmitted among patients through use of extrinsically contaminated multidose albuterol vials. Respiratory therapy departments must pay close attention to infection control practices, particularly among new or temporary staff.

Susceptibility of multiresistant strains of Burkholderia cepacia to honey

Twenty strains of Burkholderia cepacia, isolated principally from the sputum of cystic fibrosis patients, were tested for their susceptibility to eight antibiotics with a modified Kirby-Bauer Disc diffusion technique. All strains exhibited multiple but not identical patterns of antibiotic resistance. The sensitivity of all strains to honey was assessed with an agar dilution method. All strains exhibited susceptibility to concentrations of honey below 6% (v/v). This suggests that honey may have a potential role in the clinical management of B. cepacia infections.

Molecular epidemiological investigation using a randomly amplified polymorphic DNA assay of Burkholderia cepacia isolates from nosocomial outbreaks

We experienced two Burkholderia cepacia outbreaks over a 1-year period. During this period, 28 B. cepacia isolates were obtained from clinical specimens, and 2 were obtained from environmental specimens (i.e., from a nebulizer solution and a nebulizer tube). These 30 isolates were subjected to the PCR-based randomly amplified polymorphic DNA (RAPD) assay as well as to pulsed-field gel electrophoresis (PFGE). In the first outbreak, in which eight patients hospitalized in the Trauma and Critical Care Center were involved, the RAPD assay revealed that all 20 isolates obtained from clinical specimens and the 2 isolates from environmental specimens had identical DNA profiles. These RAPD data enabled us to pinpoint a possible source and to take countermeasures to prevent further spread of the epidemic-causing strain. In the second outbreak, two consecutive B. cepacia infection/colonization cases were seen in the surgery ward. The RAPD profiles of four isolates obtained were again identical, but they were distinct from those seen in the first outbreak, clearly indicating that the second outbreak was not related to the first. Thus, our experience demonstrated that the RAPD assay is a useful and reliable tool for epidemiological studies of B. cepacia isolates from nosocomial outbreaks. Since the RAPD assay could provide discriminatory potential and reproducibility comparable to those of the widely used PFGE assay with less complexity and in a shorter time, the introduction of the RAPD assay into hospital microbiology laboratories as a routine technique may help prevent nosocomial outbreaks.

Genotypic and phenotypic relationships in Burkholderia cepacia isolated from cystic fibrosis patients and the environment

Twenty-one strains of Burkholderia cepacia isolated from the environment, and 21 clinical strains isolated principally from sputum of cystic fibrosis (CF) patients, were characterized genotypically by macrorestriction analysis (genome fingerprinting) and PCR ribotyping, and phenotypically by susceptibility to antibiotics and the ability to macerate onion tissue. The plasmid content of the strains was also investigated. Environmental isolates showed a high degree of genetic variability, all strains differing from both one another and the CF isolates. The CF isolates were less variable, with common strains found in patients attending three geographically distinct CF centres. Phenotypic variation was found both within and between CF and environmental strains. Generally, CF isolates displayed higher levels of antibiotic resistance, while the ability to macerate onion tissue was more prevalent amongst environmental isolates. Plasmids were more frequently found in CF isolates, but were of similar size in both groups of strains. Such variability is not surprising in view of the existence of multiple genomovars within the B. cepacia complex.

Burkholderia cepacia. Management issues and new insights

Although Burkholderia cepacia colonizes a relatively small proportion of individuals with cystic fibrosis (CF), it is associated with significant morbidity and mortality, and has had a profound impact on infection control practices. This article reviews the current understanding of the epidemiology of B. cepacia infection, describes important recent developments in the microbiology and taxonomy of this species, and presents issues that remain obstacles to defining the optimal management of B. cepacia infection in CF.

Comparison of culture and PCR for detection of Burkholderia cepacia in sputum samples of patients with cystic fibrosis

We investigated the utility of PCR to detect Burkholderia cepacia directly in sputum samples at two cystic fibrosis (CF) centers serving children and adults. Following liquefaction of the sputa by using N-acetyl-L-cysteine, DNA was isolated and analyzed by PCRs with three different primer pairs directed toward bacterial rRNA loci. Two primer pairs were putatively specific for B. cepacia. The other pair, which universally amplifies a band from all bacteria, served as a control. Sputum samples were obtained from 219 patients and analyzed independently by culture and by PCR to detect B. cepacia. The analyses were performed blinded with respect to each other. The results of the PCR with sputa demonstrated that the primers directed to the 16S loci demonstrated approximately 95% concordance with culture results and were more specific than those amplifying the 16S to 23S spacer region. In addition, the 16S primer pair putatively identified B. cepacia in seven patients whose sputa were culture negative at this time. Of these culture-negative patients, five had sputum samples that were culture positive for B. cepacia either prior or subsequent to this study. The results of this study indicate the utility of PCR as a diagnostic method for the rapid identification of B. cepacia in sputum samples of CF patients. We anticipate that improvements in our taxonomic understanding may allow the design of more specific primers for detection of each species of the B. cepacia complex in sputum samples.