Last month I asked for suggestions from all about possible candidates for our next microbe of the month. I received many excellent ideas and these will be addressed in coming editions. However, this month the winner is Citrobacter!
It turns out that our fearless leader [redacted] has a special place in [redacted] heart for this particular microorganism. Not only does this confirm that [redacted] is as big a nerd as the rest of us it also proves [redacted] has a very refined taste in microbes. Lol!
Does anyone know the etymology of the word Citrobacter? Hint, it has nothing to do with oranges. That said I have always thought Citrobacter could be a great name for a line of citrus themed air fresheners. Turns out the actual origin is fairly boring. Essentially it means citrate utilizing rod, yawn.
The genus Citrobacter is especially relevant for food microbiologists because they share many very similar genetic, phenotypic, and biochemical traits with Salmonella. PCR, antibody, and biochemical based tests for Salmonella can sometimes be “fooled” into thinking Citrobacter is Salmonella resulting in false positives. Unlike Salmonella it is an opportunistic pathogen. While they can cause wound infections and rarely infections of the eye they are not typically considered foodborne pathogens. That said it is estimated that they are responsible for 3–6% of hospital acquired infections with Enterobacteriaceae.
Much like Listeria the taxonomic classification of Citrobacter is somewhat controversial at the moment. In general it is recognized that there are at least twelve species of Citrobacter. If you put ten taxonomists in a room together and asked them to agree on ten things they would give you one hundred different answers. Hah!
The trivia question this month should be an easy one:
Citrobacter freundii is one of the more common species of Citrobacter isolated from foods and the environment. What is the etymology of the name and for what is the bacteriologist who first described this microbe most famous?
As always you have until the end of the month to answer. The first, most accurate, and most comprehensive answer will be the winner.
Daniel DeMarco, Ph.D.