Bacterial Causes of UTIs and Cases Flashcards Preview

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Flashcards in Bacterial Causes of UTIs and Cases Deck (39)

Are UTIs a predominant infection of women?



What is often the pathogenesis of UTIs?

- colonization of introitus by uropathogens from the fecal (gut) flora establish infection by ascending from the urethra into the bladder.


How does seeding of the kidneys occur?

- from bacteremia or bacteria in the lymphatics.


What factors influence the pathogenesis of a UTI?

- organism, host, and environmental factors


What are the sources of catheter-associated UTIs?

- patient's bowel (periurethral), hands of personnel, solutions, and instruments (interluminal).
*formation of a BIOFILM on catheter affects treatment and prevention strategies.


** What are the most common bacterial causes of UNCOMPLICATED acute cystitis and pyelonephritis?

- E. coli (up to 95%)
- Staph saprophyticus (5-15%)= "honeymoon cystitis"
- Klebsiella, Proteus, Enterococci
*have PILI that allow these organisms to bind.


Are most pathogens associated with UTIs gram negative facultative anerobes?

YES, bc these are the main bacteria of the gut.


** What are the most common opportunistic bacterial causes of COMPLICATED/CATHETERIZED acute cystitis and pyelonephritis?

- E. coli (up to 50%)
- Proteus mirabilis
- Klebsiella pneumoniae
- Pseudomonas aeruginosa
- Enterococci
- Serratia
- Enterobacter
- Staph aureus
- Staph epidermidis


** What are some unusual pathogens associated with cystitis?

- Adenovirus
- Ureaplasma and Mycoplasma
- Candida albicans
- M. tuberculosis


**** What is the most common agent of all UTIs? (SKETCHY)

E. coli:
- gram negative bacillus
- virulence of uropathogenic strains (UPEC)
- type 1 fimbriae
- antibiotic resistance is rising
- urine dipstick POSITIVE for NITRITES (true for most gram negatives)
- lactose +


**** What is important to know about Staph saprophyticus? (SKETCHY)

- gram +
- causes 5-15% of community acquired UTIs in newly sexually active women ("honeymoon cystitis")
- urine dipstick NEGATIVE for nitrites.
- novobiocin-RESISTANT


**** What is important to know about Klebsiella? (SKETCHY)

- GI tract of humans
- gram -
- antibiotic resistance due to carbapenemases.
- urine dipstick POSITIVE for nitrites
- lactose +


**** What is important to know about Proteus? (SKETCHY)

- gram - (Enterobacteriaceae)
- swarming MOTILITY
- produces a LOT of UREASE= breaks up urea to ammonia (increasing pH) leading to bacterial growth and STAGHORN struvite STONES.
- usually long term catheterization.


What is important to know about Providencia and Morganella?

- they only cause infection in immunocompromised and pts with chronic indwelling catheters.
- antibiotic resistance is a big problem.
- gram - and urease positive (similar to Proteus).


**** What is important to know about Pseudomonas aeruginosa? (SKETCHY)

- gram -
- ubiquitous in health-care environment
- associated with foregin body in urinary tract.
- antibiotic resistance is a major problem.


*** What is important to know about Serratia? (SKETCHY)

- gram -
- causes mostly hospital associated infections
- moist environments
- produces RED PIGMENT
- MOTILE and antibiotic resistance.
*redness around toilet.


**** What is important to know about Enterococcus? (SKETCHY)

- gram +
- normal flora of GI tract
- occurs following treatment with broad spectrum antibiotics.
- can grow at 45 C and in 6.5% NaCl (KNOW THIS)
- Vancomycin resistance (VRE)


**** What is important to know about Staph epidermidis?

- MOST ABUNDANT species on the SKIN.
- hospital acquired
- forms BIOFILMS on plastic devices.
- catheter-associated UTIs
- gram +
- novobiocin-SENSITIVE


What is important to know about Enterobacter? (SKETCHY) Not on this test

- nosocomial pathogen (hospital acquired)


What are some other bacteria that cause resistant hospital acquired UTIs?

- Citrobacter
- Acinetobacter baumannii
- Candida albicans


What does contamination mean?

- organisms are introduced during collection or processing of urine. No health care concerns.


What does colonization mean?

- organisms are present in the urine, but are causing no illness or symptoms (asymptomatic bacteriuria). Depending on the circumstances, the patient may not need treatment.


What does infection (UTI) mean?

- the combination of a pathogen(s) within the urinary system and human host symptoms and/or inflammatory response to the pathogen(s). Treatment and management needed.


*** What does uncomplicated UTI mean?

- infection in a healthy patient with normal GU tract.


*** Is a UTI in a male always complicated?



*** What is a complicated UTI?

- infection associated with factors that increase chance of acquiring bacteria and decrease efficacy of therapy. Also requires one or all of the following:
- abnormal GU tract (BPH, stone, bladder, diverticulum, neurogenic bladder).
- immunocompromised
- multi-drug resistant bacteria


What is a recurrent UTI?

- occurs after documented infection that had resolved


What is reinfection UTI?

- a new event with reintroduction of different bacteria into GU tract


What is persistent UTI?

- recurrent UTI caused by same bacteria


*** A 47 y/o male has UTI symptoms. His urinalysis is positive for WBCs, RBCs, nitrite, and leukocyte esterase. Which pathogen is most likely implicated?
A. Staph aureus
B. Staph saprophyticus
C. Klebsiella
D. Coagulase negative Strep
E. Clostridium difficile

C. Klebsiella (bc nitrite positive is for gram - bacteria).


**** How do we treat uncomplicated UTI (cystitits, some pyelonephritis)? (TEST QUESTION)

- 3 day course of oral TMP/SMX (Bactrim)
- use fluroquinolones if resistant.


How do we treat complicated UTI (acute febrile pyelonephritis)?

- empiric parenteral treatment after culture. Start with cephalosporins, aminoglycosides, ampicillin, or vancomycin).
- switch from IV to oral after 48 hours if doing well.
- treat for 14 days.


How do we treat epididymitis?

- TMP/SMX or fluoroquinolones for at least 3 weeks to obtain adequate tissue levels.


How do we treat acute and chronic bacterial prostatitis?

- TMP/SMX or fluoroquinolones for 4 weeks (acute) or 6-12 weeks (chronic).


For what does asymptomatic bacteruria increase a pregnant woman's risk, and what antibiotics are safe in pregnancy?

- premature delivery
- low birth weight
- pyelonephritis
*amoxicillin, ampicillin, clindamycin, erythromycin, penicillin, and nitrofurantoin are all SAFE in PREGNANCY.


**** A pregnant woman has asymptomatic bacteruria. Which of the following antibiotics is an appropriate treatment?
A. Nitrofurantoin
B. Tetracycline
D. Ciprofloxacin
E. Metronidazole

- A. Nitrofurantoin


**** An 84 y/o male is hospitalized in the ICU after a bowel perforation. He is on broad spectrum antibiotics. He is persistently febrile. He has a foley catheter in place. His UA is remarkable for WBCs TNTC and blood. No bacteria is seen. A urine culture obtained is positive for candida albicans. With 10x microscopy, you would see:
A. unicellular budding yeast
B. gram negative intracellular organisms
C. hyphae
D. pseudohyphae
E. intracellular spores



What is the basic principle of infection or obstruction?

- prompt drainage of urinary tract


**** A 60 y/o female from a nursing home is hospitalized for febrile UTI. A KUB obtained shows a full staghorn calculus of the left collecting system. The mechanism by which the bacteria that are likely infecting the stone raise urine pH is?
A. Conversion of nitrate to nitrite
B. blocking the transport of branch chain amino acids
C. the hydrolysis of urea to ammonium and CO2
D. the hydrolysis of ammonium to urea
E. Intracellular sequestration of H+

- C. the hydrolysis of urea to ammonium and CO2 (this is the action of Proteus).