You have isolated an organi sm from the urine of Patient X, a 24 year old female

Question

You have isolated an organi sm from the urine of Patient X, a 24 year old female. It is showing amma hemolysis on blood agar and the col onies are large with an entire margin and are white in color. You perform a gram stain with the results pictured below. You perform a catalase test and it produces bubbles. You next perform an oxidase test and it is oxidase negative. 1. What is the next step to take in identifying the organi sm'? 2. If your test is positive, what is the genus and species of the organism? If the test is negative, what further test needs to be done to further confirm the negative result? 3. If the result is truly negative, what further testing needs to be run on this particular specimen? In other words, what organism of this type can cause urinary tract infections in sexually active females and how is it tested? (You will need to do some research to find out these results.) 4.

Explanation / Answer

1. Coagulase test and novobiocin disc test can be done. If the coagulase is negative and the organism is resistant to Noviobiocin, then the organism can be easily identified.

2. The genus is Staphylococcus and the species is saprophyticus.Staphylococcus saprophyticus is uniquely associated with uncomplicated urinary tract infection (UTI) in humans.

3. If the test is negative then further biochemical test and antibiotic susceptibilty test need to be done as it is very noted that the organism is Gram positive cocci and will belong to staphylococcus family as the result shows that it is catalase positive and oxidase negative.

4. Less common gram-positive bacterial isolates like Enterococcus faecalis (group D streptococci) and Streptococcus agalactiae (group B streptococci) which may be contaminants seen in the urine sample.

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