Duck, duck, goose – diagnosis of avian botulism redefined

This article was provided by Microbiology International, Don Whitley Scientific’s US distributor of Anaerobic Workstations.

Large outbreaks of avian botulism with losses of over 50,000 wild birds occur regularly in Canada and the United States, and poultry farms worldwide also experience serious losses due to botulism neurotoxins. Clostridium botulinum is an obligate anaerobe that produces spores that persist for many years, and the botulinum toxin is one of the most potent toxins known to man.

Workstation users Le Marechal et al. at ANSES in France have previously developed a reliable, rapid and less expensive alternative to the mouse bioassay for confirmation of botulism, using liver from birds exhibiting symptoms as matrices for real-time PCR.  In their new paper “Development and Validation of a New Reliable Method for the Diagnosis of Avian Botulism”, Le Marechal et al. describe their investigation into optimised consensus conditions for the detection of type III avian botulism strains in liver.

The group at ANSES examined a number of parameters in developing their assay, including the options for pooling samples at different time points; times and temperatures of storage; homogenisation methods; and methods for producing anaerobic culture conditions. Both naturally contaminated and spiked liver samples were incubated in anaerobic jars, using either Gas-Paks or an anaerobic gas mix (10% CO₂, 10% H₂ and 80% N₂), or in the Don Whitley Scientific A35 anaerobic workstation. Results were unambiguous: detection of low levels of some spores in anaerobic jars was only ~30% (gas mix) and ~65% (Gas-Pak) of the detection achieved in the A35 anaerobic chamber. The authors conclude that “Anaerobic chambers should therefore be preferred to detect low levels of type C spores.”

The A35, distributed in the US by Microbiology International, achieves reliably anaerobic culture conditions throughout the full internal volume of the chamber; the optional “anaerobic conditions monitoring system” senses and displays real-time oxygen levels for added security. Features such as automated humidity control, glove-less access ports, airlock and single-plate entry into the chamber, password protected user interaction and a removable front make the A35 the most user-friendly and reliable anaerobic workstation available to microbiology labs.

It’s no wonder Le Marechal et al. conclude, “The use of an anaerobic chamber was also better than the use of an anaerobic container, regardless of the anaerobic atmosphere. Therefore, insofar as possible, the use of an anaerobic chamber for the detection of C. botulinum group III is recommended, especially for the detection of a low level of spores”.