Why Test For Pseudomonas aeruginosa?

Pseudomonas spp. are a group of Gram-negative, rod-shaped, aerobic, non-spore-forming bacteria that are catalase and oxidase-positive. These bacteria are known for their resistance to penicillin and other beta-lactam antibiotics, and for their ability to produce enzymes that can affect the overall quality of food products.

Sources of Contamination:

Pseudomonas bacteria are commonly found in soil, water, and on plants.
They have a growth temperature range from 2 degrees Celsius to 35 degrees Celsius, and are psychotropic, which means they can grow at low temperatures ranging from 0 degrees Celsius to 7 degrees Celsius.
This makes the bacteria the dominant species on meat products stored aerobically.
Various foods harbor very diverse Pseudomonas spp., with some capable of secreting enzymes that can affect the overall quality of food products, including cold-stored foods like meat and foods prepared at room temperature.

Testing for Pseudomonas aeruginosa:

At FCS, Pseudomonas spp. is tested by preparing the sample and carrying out a dilution series.
The sample suspension is transferred and evenly spread onto two agar plates containing Cetrimide, Fucidin, and cephaloridine (CFC).
Once the sample has dried on the agar, it is incubated aerobically at ±25 degrees Celsius for ±44 hours.
Any growth present on the plates is taken as presumptive evidence of Pseudomonas spp. as CFC is a selective media for Pseudomonas spp.
These presumptive colonies are then streaked onto nutrient agar plates for confirmation and incubated again at ±25 degrees Celsius for 24 hours.
After the incubation, a well-isolated colony from each plate is selected and half of this colony is then added to an oxidase strip, while the other half of the colony is streaked onto a slant surface of a Kligler’s agar test tube.
If the Kligler agar test tube slant shows a red slant and butt, this confirms Pseudomonas spp.

Preventing Pseudomonas aeruginosa Food Poisoning:

Maintain the cold chain of foods to prevent the growth of bacteria on food products.
Control raw ingredients.
Practice proper personal hygiene.
Prevent cross-contamination.
Clean and disinfect equipment.
Following guidelines such as Good Manufacturing Practice (GMPs), Good Hygienic Practices (GHPs), and Hazard Analysis and Critical Control Points (HACCP) can also help prevent the spread of the bacteria.