Pseudomonas aeruginosa

Pseudomonas aeruginosa is a gram-negative, rod-shaped bacterium that has been identified in humans and plants. P. aeruginosa is commonly found in moist locations, such as soil and water, which happen to be the two most common growth media for cannabis. It’s no surprise then, that P. aeruginosa has been identified on cannabis samples.

Why is Pseudomonas aeruginosa dangerous to cannabis users?

P. aeruginosa it is an opportunistic pathogen that can infect the respiratory system of patients with weakened immune defenses. The bacterium has a tendency to persist in bronchiectatic airways, due to its ability to produce virulence factors and modulate immune defenses by quorum signaling and biofilm production.

P. aeruginosa is one of the most common bacterial pathogens found in patients with bronchiectasis, a respiratory condition that causes damage to the bronchi and bronchioles and leaves patients susceptible to bacteria infections.

P. aeruginosa is also a frequent cause of ventilator-associated pneumonia. Pseudomonas bronchitis is common late in the course of cystic fibrosis. Isolates from patients with cystic fibrosis have a characteristic mucoid colonial morphology and result in a worse prognosis than nonmucoid Pseudomonas.

A study published in 2017 describes a case where a patient developed a “cataclysmic pulmonary infection” from smoking cannabis with a bong contaminated with P. aeruginosa. It’s unclear whether the cannabis contaminated the device, but the case still shows cannabis users can acquire a life-threatening P. aeruginosa infection from cannabis use.

Who requires Pseudomonas aeruginosa testing on cannabis?

• Berkeley, CA
• Colorado*
• Connecticut
• Delaware
• New York*

*Only required for select matrices, view our Cannabis Microbial Testing Regulations by State page for more information

Test for Pseudomonas aeruginosa with PathoSEEK

Labs can use our PathoSEEK^® Microbial Safety Testing Platform to test for P. aeruginosa in a variety of cannabis matrices. The PathoSEEK Platform is the only method designed for and validated on cannabis flower, extracts, and a variety of infused products.

Important note: The P. aeruginosa assay has been shown (via Sanger sequencing of the amplicons) to amplify Pseudomonas rhizosphaerae, an off-target species. P. rhizosphaerae has been found on some hemp plants in Canada. We have designed our Pseudomonas assay to target closely-related P. aeruginosa strains that are pathogenic to humans and listed in the Cystic Fibrosis literature. The exclusion criteria for these primers did not include microbes that are not available in tissue banks, such as P. rhizosphaerae. The health risks of beneficial microbes still need to be scrutinized for agricultural products that are inhaled. To date, we are not aware of any clinical reports of harm from P. rhizosphaerae.

P. rhizosphaerae  is not commercially available from ATCC (American Type Culture Collection) for purchase and identification, thus it is difficult to ascertain if it forms colonies and to what extent this species is inflating the CFU/g estimates from the P. aeruginosa assay. We are actively investigating primers that exclude this beneficial microbe and are open to collaboration with laboratories that have specific experience culturing and quantifying this microbe.

Available Pseudomonas aeruginosa Products