Burkholderia cepacia: Introduction, Morphology, Pathogenicity, Lab Diagnosis, Treatment, Prevention, and Keynotes

Introduction

Burkholderia cepacia is a species of gram-negative bacteria within the Burkholderia genus. It is a versatile and opportunistic pathogen that can cause infections in both immunocompromised and healthy individuals. B. cepacia is a significant concern, particularly in individuals with cystic fibrosis (CF) and other chronic respiratory conditions.

Here are some key points about Burkholderia cepacia:

1. Taxonomy and classification: It was previously classified as part of the Pseudomonas genus but was later reclassified into the Burkholderia genus. It is a member of the B. cepacia complex (BCC), which includes several closely related species.
2. Opportunistic pathogen: B. cepacia is considered an opportunistic pathogen, meaning it typically causes infections in individuals with weakened immune systems or compromised lung function. It can cause a range of infections, including respiratory tract infections, bloodstream infections, urinary tract infections, and skin and soft tissue infections.
3. Infections in cystic fibrosis (CF): B. cepacia infections are of particular concern in individuals with CF. In CF patients, B. cepacia infections can lead to a condition called cepacia syndrome, characterized by a rapid decline in lung function and poor prognosis. B. cepacia is associated with increased morbidity and mortality in CF patients and is a significant challenge in managing CF care.
4. Antibiotic resistance: B. cepacia is known for its intrinsic and acquired resistance to various antibiotics, making treatment challenging. It has the ability to develop resistance mechanisms and can form biofilms, which contribute to its resilience and persistence.
5. Nosocomial infections: It is often associated with healthcare-associated infections, particularly in intensive care units and among patients with prolonged hospital stays. Strict infection control measures are necessary to prevent its spread in healthcare settings.
6. Transmissibility: It can be transmitted through person-to-person contact, contaminated medical equipment, or exposure to contaminated water sources or environmental reservoirs. Infection control practices, including proper disinfection and hygiene measures, are crucial to prevent transmission.
7. Laboratory diagnosis: Laboratory diagnosis of Burkholderia cepacia infections involves the isolation and identification of the bacteria from clinical specimens. This includes culture on selective media and subsequent identification using biochemical tests and molecular techniques.
8. Management and treatment: The treatment of theses infections is challenging due to its intrinsic resistance to many antibiotics. Individualized treatment regimens are developed based on antimicrobial susceptibility testing and the specific clinical situation. Combination antibiotic therapy may be required, and treatment is often prolonged.

It’s important to note that while B. cepacia can cause serious infections, not all strains or isolates are necessarily pathogenic. The virulence and clinical significance may vary among different strains within the species.

Morphology

The morphology of Burkholderia cepacia refers to the physical characteristics and appearance of the bacteria. Here are the typical morphological features of B. cepacia:

1. Shape: Burkholderia cepacia is a gram-negative bacterium, which means it has a thin peptidoglycan layer and an outer membrane. The shape of B. cepacia is generally described as rod-shaped or bacillus-shaped.
2. Size: The size of it can vary, but it is typically around 1-2 micrometers in width and 1-3 micrometers in length.
3. Arrangement: B. cepacia cells usually occur singly or in pairs, although they can also form short chains or clusters.
4. Motility: it is typically motile due to the presence of flagella. The flagella allow the bacteria to move in a characteristic swarming pattern on solid agar surfaces.
5. Capsule: Some strains of it may produce a polysaccharide capsule surrounding the cell, which can provide additional protection against the immune system and contribute to pathogenicity.
6. Pigmentation: B. cepacia colonies on agar media are often non-pigmented or exhibit various shades of white, cream, or gray. However, some strains may produce pigments, leading to the formation of colored colonies, such as yellow or brown.

It’s important to note that the morphological characteristics of B. cepacia can vary slightly depending on the growth conditions and specific strain or isolate being observed. To obtain a more accurate identification, additional tests and techniques, such as biochemical tests and molecular methods, are typically employed.

Pathogenicity

B. cepacia is known to be an opportunistic pathogen that can cause a range of infections in susceptible individuals. While it can be a harmless environmental bacterium, certain strains of Burkholderia cepacia have the potential to cause infections, especially in individuals with compromised immune systems or underlying respiratory conditions such as cystic fibrosis (CF). Here are key points regarding the pathogenicity of B. cepacia:

1. Cystic Fibrosis (CF): Burkholderia cepacia infections pose a significant threat to individuals with CF. In these patients, B. cepacia can colonize the respiratory tract, leading to chronic lung infections. The bacteria have a remarkable ability to persist and survive in the respiratory environment of CF patients, causing inflammation, lung damage, and a decline in lung function.
2. Opportunistic infections: It is also associated with opportunistic infections in individuals with weakened immune systems or underlying conditions, such as chronic lung disease, cancer, or those receiving immunosuppressive therapies. It can cause bloodstream infections, urinary tract infections, skin and soft tissue infections, and infections at other sites.
3. Virulence factors: It possesses various virulence factors that contribute to its pathogenicity. These factors include adhesion molecules that help the bacteria attach to host cells and colonize the respiratory tract, secretion systems for delivering toxins and effector molecules, and enzymes that facilitate tissue damage and immune evasion.
4. Biofilm formation: It has the ability to form biofilms, which are complex communities of bacteria enclosed in a self-produced matrix. Biofilms contribute to the bacteria’s ability to persist in the respiratory tract and other sites, making them more resistant to antibiotics and host immune responses.
5. Antibiotic resistance: It is known for its intrinsic and acquired resistance to multiple antibiotics. This resistance can make the treatment of infections challenging and limit the available therapeutic options.
6. Epidemics and outbreaks: In certain settings, such as healthcare facilities or among vulnerable populations, B. cepacia infections have been associated with epidemics or outbreaks. Strict infection control measures are crucial to prevent the spread of the bacteria in such situations.
7. Host susceptibility: The severity of theses infections can vary among individuals, depending on their underlying health status, immune function, and genetic factors. Some strains of the bacteria may be more virulent than others, leading to variations in disease presentation and outcomes.

It’s important to note that not all strains of B. cepacia exhibit the same level of pathogenicity, and the clinical significance of an isolate may vary. Prompt identification, monitoring, and appropriate treatment are essential in managing Burkholderia cepacia infections, particularly in high-risk populations.

Lab Diagnosis

The laboratory diagnosis of Burkholderia cepacia infections involves several steps to identify and confirm the presence of the bacteria. Here is an overview of the laboratory diagnostic methods commonly used for B. cepacia:

1. Sample collection: The appropriate clinical specimens, depending on the suspected site of infection, are collected. These may include respiratory samples (sputum, bronchoalveolar lavage), blood, urine, wound swabs, or other relevant samples.
2. Culture: The collected samples are inoculated onto appropriate culture media. Selective media such as Burkholderia cepacia selective agar (BCSA) or Burkholderia cepacia selective enrichment broth (BCSEB) can be used to promote the growth of B. cepacia while inhibiting the growth of other bacteria.
3. Identification: Identification of this bacterium involves a combination of phenotypic and genotypic methods:
   • Phenotypic identification: Initial identification of the isolate can be done using various biochemical tests, including oxidase test, catalase test, and carbohydrate fermentation tests. It typically produces oxidase and catalase, and it does not ferment lactose or sucrose.
   • Molecular identification: Molecular techniques such as polymerase chain reaction (PCR) can be employed to detect specific genes or DNA sequences that are unique to B. cepacia. PCR assays targeting genes like recA or the 16S rRNA gene can be used for species-specific identification.
4. Antimicrobial susceptibility testing: Antimicrobial susceptibility testing should be performed on B. cepacia isolates to determine the appropriate treatment options. This helps identify the susceptibility or resistance of the bacteria to various antibiotics. Testing methods, such as the disk diffusion method or broth microdilution, are commonly used.

It is important to note that the laboratory diagnosis of Burkholderia cepacia infections requires specialized techniques and expertise. Therefore, it is recommended to consult with clinical microbiology laboratories or infectious disease specialists for guidance on appropriate sample collection, culture conditions, and identification methods specific to Burkholderia cepacia.

Additionally, the interpretation of laboratory results should be done in conjunction with the patient’s clinical presentation and other relevant factors to make an accurate diagnosis and guide appropriate treatment.

Treatment

The treatment of Burkholderia cepacia infections can be challenging due to the inherent resistance of the bacteria to multiple antibiotics and its ability to form biofilms. The approach to treatment may vary depending on the site of infection, the severity of the infection, and the antimicrobial susceptibility profile of the specific strain of B. cepacia. Here are some key points regarding the treatment of Burkholderia cepacia infections:

1. Antimicrobial susceptibility testing: It is essential to perform antimicrobial susceptibility testing on the isolated strain of Burkholderia cepacia. This helps determine the susceptibility or resistance of the bacteria to various antibiotics and guides the selection of appropriate antimicrobial agents.
2. Combination therapy: Combination antibiotic therapy is often recommended for the treatment of Burkholderia cepacia infections. The rationale behind combination therapy is to target multiple pathways and enhance the effectiveness of treatment. Combinations of antibiotics from different classes, such as beta-lactams, fluoroquinolones, and trimethoprim-sulfamethoxazole, may be used.
3. Intravenous and/or inhaled antibiotics: In severe cases of theses infections, intravenous antibiotics are typically administered to achieve adequate systemic drug levels. Additionally, inhaled antibiotics can be used to directly target the respiratory tract in patients with respiratory infections.
4. Duration of treatment: The duration of treatment for Burkholderia cepacia infections is typically prolonged, often lasting weeks to months. The duration depends on the site and severity of the infection, the response to treatment, and the individual patient’s clinical condition.
5. Multidisciplinary approach: The management of Burkholderia cepacia infections often involves a multidisciplinary team, including infectious disease specialists, pulmonologists, and other healthcare professionals. Close monitoring, regular follow-up, and adjustment of treatment based on clinical and microbiological responses are crucial.
6. Infection control measures: Strict infection control measures should be implemented to prevent the spread of Burkholderia cepacia infections, especially in healthcare settings. This includes adherence to hand hygiene, proper disinfection practices, and appropriate isolation precautions.
7. Individualized approach: The treatment approach for Burkholderia cepacia infections should be individualized, taking into account factors such as the patient’s overall health, immune status, underlying conditions, and potential drug interactions.

It is important to consult with infectious disease specialists and healthcare professionals experienced in managing Burkholderia cepacia infections for specific treatment recommendations and to ensure the most appropriate approach for each individual case.

Prevention

Preventing the spread of Burkholderia cepacia infections is crucial, especially in healthcare settings and among vulnerable populations such as individuals with cystic fibrosis (CF). Here are some key measures for the prevention of B. cepacia:

1. Infection control practices: Implement and adhere to rigorous infection control practices in healthcare facilities. This includes proper hand hygiene (handwashing or hand sanitization), using appropriate personal protective equipment (gloves, gowns, masks), and following standard precautions for patient care.
2. Environmental cleaning: Maintain a clean and hygienic environment in healthcare facilities, including regular cleaning and disinfection of patient care areas, equipment, and surfaces. Use appropriate disinfectants effective against B. cepacia.
3. Water management: Ensure proper water management and maintenance systems in healthcare facilities to prevent waterborne transmission of Burkholderia cepacia. Regular monitoring and testing of water sources, particularly in areas where vulnerable individuals are present, is important.
4. Patient segregation: In healthcare settings, segregate patients colonized or infected with Burkholderia cepacia from other patients, especially those at high risk, such as individuals with CF. Implement appropriate isolation precautions to minimize the risk of transmission.
5. Screening and surveillance: Consider regular screening and surveillance of high-risk individuals, such as CF patients, to identify Burkholderia cepacia colonization or infection. This can help in early detection and timely implementation of infection control measures.
6. Education and awareness: Provide education and training to healthcare personnel, patients, and their families regarding Burkholderia cepacia, its transmission, and prevention measures. This includes promoting good respiratory hygiene, adherence to infection control practices, and understanding the importance of proper hand hygiene.
7. Patient and family education: Educate patients and their families about the importance of hygiene practices, such as regular handwashing, proper cleaning of medical equipment, and adherence to prescribed infection control measures.
8. Antibiotic stewardship: Promote appropriate and judicious use of antibiotics to minimize the development and spread of antibiotic-resistant strains of B. cepacia.
9. Communication and collaboration: Foster communication and collaboration among healthcare providers, infection control teams, and laboratory personnel to ensure prompt identification, reporting, and appropriate management of Burkholderia cepacia infections.

Prevention of Burkholderia cepacia infections requires a comprehensive and multi-faceted approach involving infection control measures, environmental management, patient education, and collaboration among healthcare professionals. Adhering to these preventive measures can help reduce the risk of transmission and protect vulnerable individuals from infection.

Keynotes

Here are some keynotes on Burkholderia cepacia:

1. It is a gram-negative bacterium belonging to the Burkholderia cepacia complex (BCC). It is an opportunistic pathogen that can cause infections in susceptible individuals, particularly those with compromised immune systems or underlying respiratory conditions like cystic fibrosis (CF).
2. In individuals with CF, Burkholderia cepacia infections can lead to chronic lung infections and a decline in lung function. Cepacia syndrome, characterized by a rapid deterioration in respiratory health, is associated with certain strains of B. cepacia in CF patients.
3. It is known for its intrinsic and acquired resistance to multiple antibiotics, making treatment challenging. Combination antibiotic therapy and individualized treatment regimens are often necessary. Prolonged treatment durations may be required.
4. The bacteria have the ability to form biofilms, which contribute to their persistence, antibiotic resistance, and ability to evade the immune system. Biofilm formation is a key factor in the pathogenesis of Burkholderia cepacia infections.
5. Burkholderia cepacia infections can be transmitted through person-to-person contact, contaminated medical equipment, or exposure to contaminated water sources. Strict infection control measures are crucial in healthcare settings to prevent the spread of infections.
6. Laboratory diagnosis of Burkholderia cepacia infections involves culture on selective media, biochemical tests, and molecular techniques for identification. Antimicrobial susceptibility testing should be performed to guide appropriate treatment.
7. Prevention of Burkholderia cepacia infections involves implementing rigorous infection control practices, maintaining a clean environment, proper water management, patient segregation, screening and surveillance, education, and collaboration among healthcare providers.
8. It has a broad host range and can infect not only humans but also animals, plants, and the environment. Some strains of Burkholderia cepacia are used in biotechnological applications, such as bioremediation and production of enzymes.

It is important to note that Burkholderia cepacia can have different strains and variations in pathogenicity, and specific clinical situations may require individualized approaches to diagnosis, treatment, and prevention. Consulting with healthcare professionals and infectious disease experts is crucial for accurate management of Burkholderia cepacia infections.

Further Readings

1. LiPuma, J.J. (2005). Burkholderia and emerging pathogens in cystic fibrosis. Seminars in Respiratory and Critical Care Medicine, 26(6), 643-654.
2. Vandamme, P., Dawyndt, P., & Coenye, T. (2005). Taxonomy and identification of the Burkholderia cepacia complex. Journal of Clinical Microbiology, 43(7), 3461-3464.
3. Mahenthiralingam, E., Urban, T.A., & Goldberg, J.B. (2005). The multifarious, multireplicon Burkholderia cepacia complex. Nature Reviews Microbiology, 3(2), 144-156.
4. Chiarini, L., Bevivino, A., Dalmastri, C., & Tabacchioni, S. (2006). Infection of Burkholderia cepacia complex in cystic fibrosis patients: virulent species and high frequency of unusual genomovars. Journal of Medical Microbiology, 55(2), 127-134.
5. Cystic Fibrosis Foundation. (2019). Burkholderia cepacia complex infection in people with cystic fibrosis. Retrieved from https://www.cff.org/What-is-CF/Testing/Infection-Prevention-and-Control/Infection-Prevention-and-Control-FAQs/Burkholderia-cepacia-complex-Infection-in-People-With-CF/
6. Drevinek, P., & Mahenthiralingam, E. (2010). Burkholderia cenocepacia in cystic fibrosis: epidemiology and molecular mechanisms of virulence. Clinical Microbiology and Infection, 16(7), 821-830.
7. Lipuma, J.J. (2010). The changing microbial epidemiology in cystic fibrosis. Clinical Microbiology Reviews, 23(2), 299-323.
8. Loutet, S.A., & Valvano, M.A. (2010). A decade of Burkholderia cenocepacia virulence determinant research. Infection and Immunity, 78(9), 4088-4100.
9. Parke, J.L., & Gurian-Sherman, D. (2001). Diversity of the Burkholderia cepacia complex and implications for risk assessment of biological control strains. Annual Review of Phytopathology, 39(1), 225-258.