Correct, my understanding is that the process is often a long complicated process to first culture and then identify bacteria (or fungal) contaminants. Not as easy as doing a 2 min. test. Sure there are some specific tests out there that doctors use such as the “rapid strep test”, but i think since even normal healthy humans carry some amount of strep and staph on their bodies and in their mouths i am not sure how definitive or specific those tests are. Plus most microorganisms don’t have such easy rapid tests and if they do they are probably often expensive and not optimized for automation or computer testing. In the case of the “rapid strep test” it looks kinda like a pregnancy test or in the lab it sorta looks like one of those blood typing clumping tests.
Perhaps some of these tests and reagents could be optimized for periodic automation testing and using a programmed camera to look for positive results. Might be interesting. Though it should be noted that there can be false negative and false positive test results. Also possible contamination from outside sources that can taint such tests.
PCR is becoming more useful for identifying bacteria, but it can not really be automated and requires some knowledge and equipment. Still such equipment is becoming cheaper thanks to cheaper technologies and the #DIYBIO community. See the OpenPCR and miniPCR projects if you are interested. The upside to PCR (in combination with gel electrophoresis or genotyping services) is that you can identify bacteria that is difficult or currently impossible to culture on artificial media.
from my limited knowledge for gram positive bacteria the catalase test is a quick and easy test to narrow down results (basically a reation with H2O2). This could potentially be automated with a reservoir and a programmed camera. Though on it’s own data from this and many of these tests is mostly useless without further tests. The coagulase test and agglutination tests are also quick and easy.
for gram negative bacteria the oxidase test is quick and easy. As is the Methyl-Red test.
all other tests to my knowledge need various and sometimes expensive Agar and require incubation.
Still, continuing on with your question…
Generally accepted traits for Salmonella and E. coli are as follows:
Bacillus shape, Gram Negative, Oxidase negative, Methyl-Red positive, Lactose Fermentation negative, Glucose Fermentation positive (with or without gas production), Citrate positive, H2S positive, Ntrate Reduction positive, Indole negative, Urea negative, Motility positive (able to move).
Bacillus shape, Gram Negative, Oxidase negative, Methyl-Red positive, Lactose Fermentation positive, Glucose Fermentation positive (+gas), Citrate negative, H2S negative, Ntrate Reduction positive, Indole positive, Urea negative, Motility positive (able to move).
It should be noted that this “standard” identification comes from good sources such as Bergey’s manual of determinative bacteriology 9th edition. But even though this book is basically the bible of microbiology and is pretty good, this information is from 1994! Things can change and mutate quickly, especially bacteria in hospital or agriculture environments, and forms of Salmonella typhimurium or E. coli that do not match these exact traits probably exist.