There are many gram negative rods that can cause urinary tract infections.
Preliminary ID's are based on lactose reaction. Lactose positives are treated
one way and Lactose negatives are treated another. All Lactose negatives with
the exception of swarming Proteus species MUST have oxidase testing performed -
oxidase positives get set up for ID differently than oxidase negatives, if
you're using conventional media. If using automated systems, e.g. Vitek, cards
must be marked with the oxidase reaction if positive. Common isolates from
UTI's other than E. coli include Klebsiella pneumoniae/oxytoca, Enterobacter
cloacae/aerogenes, Citrobacter freundii/amalonaticus, Serratia marcescens,
Proteus mirabilis/vulgaris, Morganella morganii, Providentia species,
Pseudomonas aeruginosa, and sometimes other bugs not commonly found. Your
charts should show you the differences in reactions amongst these.
All clinical labs have different protocols and ID systems for identifying the
above organisms, which make up the bulk of the gram negative rods encountered in
the clinical laboratory. I learned with conventional tube media, which I still
can visualize in my head whenever I picture an identification. It's a great way
to learn your ID's. Over the years I've used Enterotube, API, and for the last
12 years at least, Vitek. Vitek is great and I really like it. However, the
automated systems don't help one learn their reactions.
The first lab I started at back in 1974, as I said, used conventional media.
The lactose positive organisms were ID'd by SIM, citrate, lysine, ornithine,
control, and VP broth. The lactose negatives/oxidase negatives used the
previous media plus (if I can remember) urea, PAD, raffinose, arginine, DNA
plate, and OF glucose (I think). Suspicious colonies on stool cultures were
screened with SIM, urea, TSI and LIA. Suspicious reactions on these media
required full identification, sensitivity, and serogrouping. I suspect that
would change nowadays, as E. coli 0157:H7 wasn't suspected as being a pathogen
way back then. Ah, the good ol' days.
Have fun Len.
Judy Dilworth, M.T. (ASCP)
Microbiology almost 26 years
> ..........but what other bugs could be suspected of UT infections such as the
> above mentioned?