A Scary Microbial Complex is on the Move
A group of organisms known collectively as BCC has prompted product recalls and warnings. Here are four things you need to know about the microbial complex
There is nothing scarier for product developers than the word recall. Companies have become really adept, with the help of partner laboratories, at detecting and identifying microbes lurking in their facilities. However, there are always going to be new microbes that challenge companies. The latest challenge comes from the Burkholderia cepacia complex (BCC), a group of organisms that have led to recalls and warnings of personal care products and pharmaceuticals.
Sunhee Hong, PhD, a respected phylogeneticist at Charles River, brings us up to date on what microbial QC laboratories can do to address this public health concern, including which tools are the best ones for species-level identification. If you would like to learn more about BCC, check out this webinar where you can learn the best way to track these bugs.
Q: What is the B. cepacia complex and why is understanding it critical for patient and consumer safety?
Burkholderia cepacia complex, or BCC, is a group of very closely related catalase-producing, lactose non-fermenting, Gram-negative bacteria that most often causes pneumonia in immunocompromised individuals. BCC organisms are typically found in water and soil, and can survive for prolonged periods in moist environments. Though BCC is certainly of great concern for those who are immunocompromised or living with cystic fibrosis, there are occasional cases in which a species in the BCC has caused serious illness in non-immunocompromised, previously healthy patients. Certain members of the BCC are highly contagious and especially virulent. With this risk to patients in mind, in recent years regulatory bodies like the FDA have taken a close look at products that contain BCC, issuing recall after recall and even an advisory statement to drug manufacturers in May of 2017, warning of the particular risk posed by BCC in non-sterile water-based products. Some examples include sanitizers, oral pharmaceuticals, eyewashes, nasal sprays, mouthwashes, skin creams, and baby and adult washcloths – the list goes on.
Q: Why is BCC such a challenge to product manufacturers?
BCC is especially troublesome because of its ability to resist preservatives and antimicrobial agents, growing even in unfavorable environments. For instance, B. multivorans, has been noted to grow well in low-nutrient environments such as distilled water, and is a good biofilm former. A recent case study shared by the FDA examined a situation in which B. multivorans was detected in a product (albeit prior to release of the product by the manufacturer). As it happened, two batches of a nasal spray containing an antimicrobial preservative were discovered during microbial testing to contain a member of the BCC.
Q: Can we stop at detection or is there a need to identify to the species level?
Aside from the need to detect the presence of B. cepacia complex species in tested samples, another important tool in the repertoire of microbiological controls is the ability to accurately identify microorganisms to the species level. B. cepacia species have proven problematic in this regard, challenging traditional methods and necessitating advances in microbial identification strategies. Many available microbial identification methods yield incorrect results or are incapable of distinguishing one species from another within the complex altogether. It is important to know which particular species is implicated in a contamination event. It is not enough to assume that any one measure (e.g., CAPA) is sufficient to eradicate all the different species, as they have distinct characteristics and may respond differently to attempts to decontaminate.
Q: What methods are suitable for BCC species-level identification?
Even 16S rRNA gene sequence analysis has limitations with differentiating some groups of closely related organisms that share a high percentage of 16S rRNA gene sequence similarity, B. cepacia complex included. Additional resolution is needed for confident speciation – such as targeting of alternate regions of the genome. Recognizing the advantages presented by the recA gene sequencing approach when attempting to speciate members of the B. cepacia complex, Charles River has developed the capability of distinguishing the BCC species from one another. Because of the novel and complex approach in targeting recA, it is imperative that microbial ID service providers use high quality sequence data, curated reference databases, and updated bacterial nomenclature and taxonomy for phylogenetic analyses in order for an identification to be accurate and reliable.