Bacterial Causes of UTIs and Cases Flashcards
Are UTIs a predominant infection of women?
YES
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.
- COPIOIUS CAPSULE
- 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 -
- OXIDASE +
- ubiquitous in health-care environment
- associated with foregin body in urinary tract.
- antibiotic resistance is a major problem.