Burkholderia cepacia complex
|Burkholderia cepacia complex|
|Species:||B. cepacia complex|
|Burkholderia cepacia complex
(Palleroni and Holmes 1981)
Yabuuchi et al. 1993
CCUG 12691 and 13226
Pseudomonas cepacia Burkholder 1950
Burkholderia cepacia complex (BCC), or simply Burkholderia cepacia is a group of catalase-producing, lactose-nonfermenting, Gram-negative bacteria composed of at least 18 different species, including B. cepacia, B. multivorans, B. cenocepacia, B. vietnamiensis, B. stabilis, B. ambifaria, B. dolosa, B. anthina, B. pyrrocinia and B. ubonensis. B. cepacia is an important human pathogen which most often causes pneumonia in immunocompromised individuals with underlying lung disease (such as cystic fibrosis or chronic granulomatous disease). Patients with sickle-cell haemoglobinopathies are also at risk. It also attacks young onion and tobacco plants, as well as displaying a remarkable ability to digest oil.
BCC organisms are typically found in water and soil and can survive for prolonged periods in moist environments. They show a relatively poor virulence, that is capacity to cause disease. Virulence factors include adherence to plastic surfaces (including those of medical devices) and production of several enzymes such as elastase and gelatinase. Also relevant might be the ability to survive to non-oxidative killing by neutrophils. Person-to-person spread has been documented; as a result, many hospitals, clinics, and camps have enacted strict isolation precautions for those infected with BCC. Infected individuals are often treated in a separate area from uninfected patients to limit spread, since BCC infection can lead to a rapid decline in lung function and result in death.
Diagnosis of BCC involves culturing the bacteria from clinical specimens, such as sputum or blood. BCC organisms are naturally resistant to many common antibiotics, including aminoglycosides and polymyxin B. and this fact is exploited in the identification of the organism. The organism is usually cultured in Burkholderia cepacia agar (BC agar) which contains crystal violet and bile salts to inhibit the growth of gram positive cocci and Ticarcillin and Polymyxin B to inhibit the growth of other gram negative bacilli. It also contains Phenol Red pH indicator which turns pink when it reacts with alkaline byproducts generated by the bacteria when it grows.
Alternatively, Oxidation-fermentation polymyxin-bacitracin-lactose (OFPBL) agar can be used. OFPBL contains polymyxin (which kills most Gram-negative bacteria, including Pseudomonas aeruginosa) and bacitracin (which kills most Gram-positive bacteria and Neisseria species). It also contains lactose, and organisms such as BCC that do not ferment lactose turn the pH indicator yellow, which helps to distinguish it from other organisms that may grow on OFPBL agar, such as Candida species, Pseudomonas fluorescens, Stenotrophomonas species, and Proteus species.
The bacterium is so hardy, it has been found to persist in betadine (a common topical antiseptic). Recently, a 0.2% chlorhexidine mouthwash was also recalled, after it was found to be contaminated with B. cepacia. On 1-August-2012, the US FDA announced a recall of selected lots of benzalkonium chloride swabs and antiseptic wipes manufactured for Dukal by Jianerkang Medical Dressing Co. Matrixx Initiatives Issues Nationwide Voluntary Recall of One Lot of Zicam® Extreme Congestion Relief Due to Contamination With Burkholderia Cepacia 
Treatment typically includes multiple antibiotics and may include ceftazidime, doxycycline, piperacillin, meropenem, chloramphenicol and trimethoprim/sulfamethoxazole(co-trimoxazole). Although co-trimoxazole has been generally considered the drug of choice for B. cepacia infections, ceftazidime, doxycycline, piperacillin and meropenem are considered to be viable alternative options in cases where co-trimoxazole cannot be administered because of hypersensitivity reactions, intolerance or resistance. In April 2007, researchers from the University of Western Ontario School of Medicine, working with a group from Edinburgh, announced that they had discovered a potential method to kill the organism, involving disruption in the biosynthesis of an essential cell membrane sugar.
B.cepacia was discovered by Walter Burkholder in 1949 as the cause of onion skin rot, and first described as a human pathogen in the 1950s. In the 1980s, it was first recognized in individuals with cystic fibrosis, and outbreaks were associated with a 35% death rate. B. cepacia has a large genome, containing twice the amount of genetic material as E. coli.
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