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The surprising secret of the Bakerella complex: Why is it so difficult to eradicate?
The Burkholderia cepacia complex (BCC) is a group of Gram-negative bacteria that includes B. cepacia and at least twenty different biochemically similar species. These bacteria are known for their ability to produce catalytic enzymes and not ferment lactose. Members of BCC may contribute to the development of pneumonia in individuals with suppressed immune systems, particularly those with underlying lung disease such as cystic fibrosis or chronic granular disease. Even young patients with thalassemia are at risk of infection.
These bacteria not only pose a threat to humans, but can also attack young onion and tobacco plants and have an amazing ability to break down oils.
Classification and distribution
The Bakerella complex includes B. cepacia, B. multivorans, B. cenocepacia, B. vietnamiensis, B. stabilis, B. ambifaria, B. dolosa, B. anthina, B. pyrrocinia and B. ubonensis, etc. species. These bacteria are commonly found in water and soil and can survive in moist environments for extended periods of time, which is one of the reasons they are difficult to eradicate.
It is worth noting that BCC is resistant to common disinfectants such as povidone-iodine, trifluorofluoride, chlorhexidine and quaternary ammonium salts.
Human infection and pathogenesis
Causative factors in BCC include attachment to plastic surfaces and the ability to secrete several enzymes such as elastase and gelatinase. These bacteria are resistant to attack by white blood cells, making them more transmissible in healthcare settings. Because human-to-human transmission has been confirmed, many hospitals and clinics have implemented strict isolation measures for patients infected with BCC to prevent rapid deterioration of the disease.
After infection, patients are often treated in an area isolated from uninfected patients to reduce the risk of spreading the infection, as BCC infection can lead to rapid decline in lung function and even death.
Diagnosing BCC usually requires culturing bacteria from clinical specimens, most commonly using Baker's agar (BC agar), which inhibits the growth of gram-positive cocci and other gram-negative bacteria.
Treatment methods
Treatment for BCC usually includes a variety of antibiotics, possibly including ceftazidime, minocycline, piracillin, meropenem, chloramphenicol, and diphenylprazole/sulfamethoxazole (combination therapy) . Although diphenylprazole is widely considered the drug of choice for B. cepacia infections, other alternatives may be considered in certain circumstances.
It is important to note that BCC is inherently resistant to many common antibiotics, such as aminoglycosides and polymyxin B, which can make treatment more difficult.
Historical background
Burkholderia was first discovered by Walter Burkholder in 1949 as the cause of onion rot, and was first described as a human pathogen in the 1950s. The bacterium was first isolated from cystic fibrosis patients in 1977 and was known as Pseudomonas cepacia. By the 1980s, outbreaks of Baker's disease among cystic fibrosis patients, with a 35% mortality rate, aroused widespread concern in the medical community.
The genome of Bakerella is very large, containing twice as much genetic material as E. coli, making it more adaptable and survivable. The concentrations used as preservatives in aqueous pharmaceutical products are often insufficient to kill or even inhibit BCC proliferation.
Confronted with this persistent pathogen, many experts are beginning to reflect on how we can more effectively manage and treat these infections. In the future, can we find a more effective way to combat this stubborn pathogen and protect the health of wider society?
