1 UTIs Flashcards
Urinary tract infections refer to infections residing in the…
Kidneys, ureters, bladder, or urethra
Examples:
Pyelonephritis (kidneys and ureters)
Urethritis (urethra)
Cystitis (bladder)
UTIs are usually initiated as the infecting bacteria contaminates…
The opening of the urethra and moves UPWARD into the urinary tract
UTIs are more common in…
Adults vs children
Female vs men
Risk factors for UTIs
Obstructions (stones) Conditions —> incomplete bladder voiding Immunosuppression Sexual activity Use of diaphragms as BC Enlarged prostate Catheterization Pregnancy
Risk factors for UTI specific to children
Poor hygiene
Partial blockage
Typical SSx of a Lower UTI
Bladder inflammation Dysuria Frequent urination Urinary urgency Cloudy, malodorous or bloody urine Lower abdominal pain or pressure MILD FEVER**** Burning with urination (urethritis)
Do you get a fever with a lower UTI?
You can but it would be mild
Usually due to inflammation rather than the bacteria themselves
SSx of an upper UTI (Pyelonephritis)
HIGH FEVER (>101˚F) Shaking Chills Nausea Vomiting Flank pain
SSx of UTIs in newborns
Fever or hypothermia
Poor feeding
Jaundice
SSx of UTIs in infants
Vomiting
Diarrhea
Poor feeding
(Mimics GI infection)
SSx of UTIs in Children
Irritability Eating poorly UNEXPLAINED FEVER Loss of bowel control (loose stools) Change in urination patterns
What is the URI-cult CLED/EMB?
Paddles used to make a presumptive ID of pathogen and CFU/ml in UTIs
ID and NUMBER***
What is the EMB side of the CLED/EMB selective for?
Gram negative bacteria
Contains BILE salts, which kill off G(+) organisms
(emB = BILE)
What does the CLED side of the CLED/EMB select for?
Growth of G+ and G- organisms
Determines ability to ferment LACTOSE
(cLed = LACTOSE)
Why is it important that the CLED/EMB paddles provide a somewhat quantitative measure of the number of organisms?
B/c a lot of these pathogens are also a part of our normal flora, so you need at least a certain amount for it to be considered an active infection
How should your urine specimen be collected in order to diagnose a UTI?
Midstream clean catch
Catch or aspiration in infants and young children
What U/A microscopy findings indicate an active infection requiring treatment?
2-5 or more WBCs or 15 bacteria per high powered microscopic field in a centrifuged urine sample
What additional diagnostic testing should be done in men presenting with UTI symptoms?
Prostate exam
Assume that there is an anatomical abnormality present that is causing it
What populations should have an U/S or CT done when diagnosing a UTI?
Children - 50% of infants with UTI have an anatomical abnormality
Adults with recurrent infections
Blood in urine
Most common bacteria causing UTI
E.coli (75-90% of all UTIs)
Specifically, Uropathogenic E.coli (UPEC)
Other less common bacterial causes of UTIs
Klebsiella spp Proteus spp Enterococcus spp Staphylococcus saprophyticus Streptococcus Group B Pseudomonas aeruginosa
Super rare:
Candida
Adenovirus
Klebsiella UTIs are rare but more common in …
Immunocompromised patients
Bacteria to be suspected in sexually active females
Staphylococcus saprophyticus
Bacteria to be suspected in neonatal UTIs
Group B Strep
Candida UTIs are super rare but when they occur, they are often the result of…
Catheterization
Super rare cause of UTI that can cause hemorrhagic cystitis
Adenovirus
Flagellated, gram-negative enteric bacillus
E.coli
What strains of E.coli are associated with meningitis?
Encapsulated (K1) strains
Meningitis infections are rare in adults but can follow neurosurgical trauma
Virulence factors for UPEC E.coli
P fimbriae (Pili)
Dr adhesins
Alpha and beta hemolysins
K (capsular) antigen
What do P fimbriae and Dr adhesins do to help UPEC E.coli infect the urinary tract?
Bind to the uroepithelial cells and erythrocytes
Dr adhesins lead to the formation of complex structures surrounding the bound bacterial cells
The alpha and beta hemolysins in UPEC E.coli result in…
Lysis of both uroepithelial cells and erythrocytes
Blood in urine? Think E.coli
When would you see K (capsular antigens)?
In upper UTI and chronic UTI due to increased formation of biofilms
Gram negative bacilli possessing fimbriae that target organism to the tissue of the UT
Proteus
What are the two Proteus spp that can cause UTI?
P. mirabilis - community acquired
P. vulgaris - predominantly infects immunocompromised
Which proteus species is community acquired?
P. mirabilis
Which proteus species predominantly infects immunocompromised?
P. vulgaris
“Swarming” on culture agar
Proteus
On what medium does proteus NOT swarm?
CLED
Where is proteus most commonly found?
Long-term care facilities and hospitals
Can be isolated from oral cavity and nasopharynx of hospital staff
Proteus virulence factors
Fimbriae (pili) promote attachment to uroepithelial cells
—> inflammation —> apoptosis of host cells —> sepsis
Produces UREASE —> hydrolyzes urea to ammonia —> alkaline urine
Struvite stones are very indicative of infection by what organism?
Proteus
Increased pH (due to UREASE) leads to formation of stones (magnesium ammonium phosphate)
Gram positive, coagulase negative staph tha tis the second leading cause of UTIs
S. saprophyticus
More prominent in females ages 17-27, incidence increased in sexually active females (organism displaced from normal flora to the urethra)
“Honeymoon cystitis”
S. saprophyticus
Most cases occur 24 hours after having sex - may manifest with razor sharp pains during intercourse
Test that will tell staph aureus apart from staph saprophyticus
Coagulase reaction
Staph aureus is the ONLY coagulase positive staph
How do you differentiate S. saprophyticus from other coagulase negative staph?
Novobiocin resistance - other coagulase negative staph are sensitive to novobiocin
Novobiocin is an abx not used clinically but diagnostic tool
Is S. saprophyticus very virulent?
No
Possesses adhesives but not a lot of destructive ability
No exotoxins
Usually low bacterial numbers (makes it harder to diagnose)
Gray-white colonies with a narrow zone of ß-hemolysis
S. agalactiae
S. agalactiae is also known as…
Group B Strep
S. agalactiae infections in adults are strongly linked with …
Underlying immunodeficiencies
S. agalactiae virulence factors
Capsular polysaccharide
Hyaluronidase
Collagenase
Hemolysin
Diagnosis of S. agalactiae includes detection of …
CAMP factor (Christie, Atkins, Munch-Peterson)
Accentuation of hemolysis due to interaction w/ staph ß-lysin
Other presumptive tests: ID of group CHO is insensitive and DNA probe
Why does S. agalactiae require a definitive diagnosis?
Because it’s an unusual cause of UTI
Requires isolation from urine, blood, CSF
Treatment of a lower UTI is much more difficult if…
Prostate is infected - put to 1 month of abx may be required
An uncomplicated UTI typically requires ______ day course of abx
1-7 day (depending on organism)
How do you treat an upper UTI?
IV fluids and abx (10-14 days) if uncomplicated
Complicated cases may require treatment courses lasting many weeks
If a patient is diagnosed with pyelonephritis AND has one of the following, they should be admitted…
Pregnant
Have not improved with outpatient abx treatment
Underlying immunocompromised status or on immunosuppressive
Unable to keep anything in stomach due to N/V
Previous kidney disease within the last 30 days
Kidney stones
Catheterized
