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Flashcards in Urinary Tract Infections Deck (40):
1

Urinary Tract Infections (General)

- very common bacterial infection
- more frequent in women due to anatomic difference
- can be single, recurrent, uncomplicated or complicated
- Urinary tract normally resistant to infection due to urine characteristics

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Upper UTI's

infection of renal parenchyma or ureters

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Lower UTI's

infection of bladder, urethra or prostate (males)

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Recurrent UTI's

- Relapse: re-infection with the same bacteria
- Reinfection: second UTI infection by different organism

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Uncomplicated UTI's

UTI's in sexually active women with normal GU tracts; no procedures

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Complicated UTI's

UTI's due to one or more structural or functional abnormalities

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Urine infection resistance

- extremely high osmolarity to inhibit growth of most organisms
- low pH
- dilute urine grows less
- prostatic fluid (men)
- flow has washing affect to inhibit adherence

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UTI Risk factors

- AGE (kids with long-term medical problems, adults with GU abnormalities, elderly because of catheterization, prostate problems, bladder prolapse)
- INSTITUTIONALIZE CARE (catheters, asymptomatic bacteruria)
- PREGNANCY (increased ASB)
- RENAL TRANSPLANT (leads to septicemia)
- BLADDER CATHETERIZATION

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Route of Infection

- Ascending route: most common route, migration from bladder, acquired UTI's
- Descending route: infection via blood, < 5% of UTI's

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UTI's (Clinical Signs/Symptoms)

- failure to thrive, vomiting, lethargy, fever in kids < 2 y/o
- dysuria, frequency and abdominal/flank pain in kids
- dysuria, frequency, urgency, suprapubic pain, hematuria in adults
- fever, costovertebral angle tenderness, flank pain, chills, vomiting in upper UTI's

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Infections in urine cultures that aren't UTI's

- Herpes simplex (HSV)
- Chlamydia trachomatis
- Neisseria gonorrhoeae

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UTI pathogenesis (women)

- infection via ascending route
- due to shorter ureter

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UTI pathogens

- Gram-positives (S. sapro, Enterococcus, S. epi) via ascending route
- Gram-negatives (E. coli, Pseudomonas, Proteus, Kleb, Acinetobacter, Enterobacter) via ascending route - from catheterization (except E. coli)
- GPR's (Bacillus, MAC, Listeria)
- Chlamydia, N. gonorrhoeae, Mycoplasma, Ureaplasma, Gardnerella, Adenovirus, HSV
- Bacteremias, endocarditis, , mycobacteria, Candida, fungal infections via hematogenous route

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UTI virulence factors

- adherence
- biofilms
- calculi formation

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- Gram positive cocci
- catalase positive, coagulase negative
- Bacitracin resistant, Novobiocin resistant

S. saprophyticus

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- Gram positive cocci
- catalse -
- Bile esculin +, growth in 6.5% NaCl, PYR +

Enterococcus

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- Gram positive cocci
- catalase +, coagulase -
- Bacitracin resistant, Novobiocin susceptible

S. epidermidis

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- GNR
- oxidase -, glucose fermenter, nitrate reducer, motile
- IMVC (++--)
- H2S -, citrate -, PAD -, A/A

E. coli

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- blue-green hue on MAC (pyoverdin and pyocyanin)
- beta hemolytic
- oxidase +, catalase +, ADH +, citrate +
- glucose oxidizer
- grows at 42C

P. aeruginosa

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- GNR
- H2S +, swarm, PAD +, urease +
- vulgaris (indole +, ODC -, A/A)
- mirabilis (indole -, ODC +, K/A)

Proteus

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- GNR
- citrate +, H2S -, PAD -, urease -, IMVC (--++)
- oxytoca (indole +)

Klebsiella

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- GNR
- oxidase -, glucose oxidizer
- NLF, but purple on MAC

Acinetobacter

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- GNR
- oxidase -, IMVC (--++), LDC + (except cloacae), ODC +
- citrate +, H2S -, PAD -, urease -

Enterobacter

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- Gram positive bacilli
- grows at 4C, catalase +
- umbrella motility at 25C, tumbling motility
- CAMP positive (block)

Listeria

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- Gram positive bacilli
- motile, beta hemolytic
- catalase positive

Bacillus (cereus)

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- inactive in most tests
- heat-stable catalase
- common Mycobacteria in US

M. avium complex (MAC)

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- intracellular parasites
- specimen on Dacron swab
- EB and RB stages of life cycle
- won't grow on a normal plate

Chlamydia trachomatis

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- Gram negative dipplococci
- oxidase -
- grows on MTM
- utilizes glucose

Neisseria gonorrhoeae

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Lab Diagnosis of UTI

- colony count: leukocyte count at least 10/mm^3 in more than 96% of patients with bacteruria
- Urine culture and other tests for diagnosis

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Types of urinary infections (women)

- Symptomatic pyuria without bacteruria
- Asymptomatic bacteruria (with or without pyuria)

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Specimen collection

- Voided midstream specimen collection (CCMS)
- Catheterized specimen collection (best for kids)
- Suprapubic aspiration (for anaerobes)
- 24hr old specimen is unacceptable
- first morning urine is best

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Specimen processing

- processed within 2 hours
- refrigerated if not processed immediately
- avoid contamination of specimen
- rapid nonculture screening or manual screening

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Microscopy

- pyuria: 5-10 leukocytes in urine
- detect fungi and mycobacteria (use acid fast stain)
- chemical tests

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Specimen rejection

Reject if inadequate collection/transportation

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Culturing urine specimens

- usually BAP and MAC
- incubate 24 hours
- plate to more plates for fastidious organisms

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Interpreting culture results

- colony count indicates level of pyuria
- presence of symptoms also indicative

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Culture with 3 or more uropathogens

probably contamination

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Culture with 2 significant uropathogens (>10^5)

identify and perform susceptibility

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Culture with 1 or 2 uropathogens (small numbers >10^2)

identify if clinical situation warrants

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Reportable results

- a pure culture of S. aureus is significant
- yeast in any culture is significant
- unusual organisms are reportable
- only report significant UTI antibiotics