Lab 2 Urinary Tract Infections Flashcards
What are the common causative agents for an UTI?
Most common causative bacteria for UTI (pathogens):
- Enterobacterales
(E. coli, Klebsiella, Proteus, others),
-other GNB (Pseudomonas),
- Enterococcus, Staphylococcus (saprophyticus in community acquired, others in nosocomial), - yeast in inpatients.
What two clinical factors (general) are important in establishing presence of a UTI?
Pyuria along with bacteriuria is also an important factor in establishing the presence of a urinary tract infection.
What are common contaminants in urinary samples?
Resident Microbiota of the urethra and skin (possible contaminants):
- Coag neg Staph,
- Viridans Strep,
- Lactobacillus,
- Corynebacterium,
- non pathogenic Neisseria spp.
Is urine considered a sterile specimen?
Urine is normally a sterile body fluid, however if the proper collection instructions are not given by the microbiologist and followed by the patient or collectors, then it can be contaminated with the patient’s flora from the perineum, prostate, urethra or vagina.
How many factors are considered and reviewed at the time of receipt of specimen in the lab? How many can you list?
- Time of collection
- Receipt time in the laboratory
- Integrity of the specimen (sterile container, not leaking or frozen, etc.)
- Examine the requisition for any missing information or inaccuracies.
- Last and full name
- Accession number
- Date of birth
- Sex
- Date and time of collection
- Test request
- Source (body site)
- If there is any clinical information, transfer it to the LIS.
What type of agar has replaced BA and MAC in current labs?
Chromogenic agar
What do you do if you see 3 or more types of bacteria in the media?
Most UTI’s are monobacterial, eventually two types can cause an infection but the presence of 3 types or more is an indication of probable contamination and a new urine specimen should be requested without working up these organisms fully.
When is a preliminary report issued to the doctor?
Preliminary Report: Once the level of workup has been determined, tests for ID are performed as soon as possible in order to be able to produce a preliminary report at 24 hours. This is usually a Gram stain to start, and then all possible spot tests, like catalase, coagulase, oxidase, indole, PYR, etc.
What subsequent tests are done if the suspected pathogen is G+C?
Gram-positive cocci: Use same tests, methods and algorithms used in Microbiology 1: cat, coag, Novobiocin, PYR, Lancefield, B.E., salt tolerance, etc.
What subsequent tests are done if the suspected pathogen is G-b?
Gram-negative bacilli: Most UTI pathogens are non-fastidious, either Enterobacterales (majority) or non-fermenters. Oxidase could be used as a helpful first test. Instead of using individual test tubes, a test system called API will be performed during this course, followed by a check plate. API 20E will be more appropriate for Enterobacterales (but some non-fermenters might be identified) and API NE could be used for non-Enterobacterales.
Is susceptibility testing typically be performed on UTI pathogens?
Yes, Kirby Bauer Method should be followed to test/report susceptibility on your unknown organism.
Remember that QC should be performed weekly for antimicrobial discs. Each bench should have their own set of QC. Please communicate with your bench members to coordinate this task.
QC results should be documented in AST QC binder.
What is the benefit of using chromogenic agar in the lab for UTI’s?
Chromogenic agar can be used to decrease the turn-around time in the identification of pathogens from clinical specimens.
There are a variety of chromagars available. Some are designed to identify resistant organisms (MRSA-VRE), yeasts and enteric pathogens.
What is the benefit of using chromogenic agar to identify UTI specimens?
E. coli and Enterococcus (which make a large percentage of UTI’s causative agents) can be identified directly from morphology, without performing other tests. Other organisms will need either minimal testing or a full ID after. For example: a PMP-looking colony with a negative indole can be called Proteus mirabilis. KES organisms might need a full ID.
