Bacterial UTI (Diebel) - W3 Flashcards
What are first line antibiotics for UTI for WOMEN
- nitrofurantoin and TMP-SMX
What are first line antibiotics for UTI in men?
- fluoroquinolone
- TMP-SMX
What is the “gold standard” for detecting bacteria in urine?
detection of bacteria in a urine culture
- may also see white cells and inflammatory cytokines
How much more common are UTIs in women than men in adults aged 20-50 years?
50x more common
What are the underlying factors that predispose an individual to an ascending bacterial infection?
- presence of urinary instrument (catheter)
- anatomic abnormalities
- obstruction of urine flow
- poor bladder emptying
- caliculi, tumors, pregnancy, neurogenic disorders, porstate enlargement, uterine prolapse, cystocele
What are risk factors for women in getting UTIs?
- sexual intercourse
- diaphragm use
- spermacide use
- antibiotic use
- hx of recurrent UTIs
What are risks for young men getting UTIs?
- unportected anal intercourse
- uncirmucised penis
- unportected intercourse w/woman whose vagina is colonized w/urinary pathogens
What are the common pathogens for uncomplicated UTIs?
- E. coli - 75%
- Staphylococcus saprophyticus - 5-15%
- Other enteric bacteria - 5-10%
- kelbsiella
- proteus
- enteroccus
- citrobacter
What are the common pathogens involved in complicated UTIs?
- E. coli - still most predominant
- other anaerobes, gram negative
- kelbseilla
- proteus
- citrobacter
- acinetobacter
- morganella
- pseudomonas
What are the factors of the ENVIRONMENT that lead to a UTI?
- colonization of vaginal introitus and periurethral area w/intestinal flora
- condition that allows for urinary stasis
- stones
- urinary catheters
HOST factors that lead to increaed risk for UTI
- increased ability of E coli to colonize through better attachment to epithelial cell surface or decreased immune response to colonization
What does E. coli contain that allow them to cause invasive symtpoms w/UTIs in otherwise normal hosts?
-
surface adhesions
- facilitate binding to epithelial cells to initiate colonization
-
P. fimbrae
- important for pyelonephritis and blood stream invasion
-
type 1 pilus (fimbria)
- key for bladder infection
What E. coli virulence factor faciliates blood stream invasition & pyelonephritis, and interacts w/specific receptor on renal epithelial cells
P. fimbriae
What are type I pili (fimbria)
faciliate what?
do all strains have?
what does it bind to?
- initiates E. coli bladder infection
- all possess genetically but not all express
- gene on chromosome but protein not always present
- mediate binding to uroplakins on luminal surface of bladder uroepithelial cells
What are the major defenses of the urinary system?
- Urine pH, lysozyme and lactoferrin
- Flow
- IgA - adaptive immune response that goes through epithelial lining
- changing surface proteins on epithelial cells
What are the major threats to the urinary system?
- micro-organisms of GI
- hematogenous spread from other areas
- blocked or decreased urine flow
For each of the following, say if they’re complicated or uncomplicated UTIs.
Parkinson’s disaease
Renal transplant
Infection in men
pregannt women
children
hospitalized patients
- ALL are complicated cases
- any neurologic disease could predispose to voiding issues
- obstruction, catheteres, immunosuppression could also be added.
- organisms are more likely to be resistant
- men - complicated since get infection of prostate w/the bladder
What is the overall UTI incidence in women and what is the reoccurence rate?
- .5-.7 episodes per year
- recur in 25-30%
Presents with high fever, flank pain, dysuria, nausea, and vomitting
Pyelonephritis
What is an infection due to acute complication of pyelonephritis
-
Papillary necrosis
- normally occurs w/ DM, UT obstruction, sickle cell disease or analgesic abuse
- necrotic renal papillae may slough and cause obstruction
- intrarenal abscess may result from bacteremia or be complication of severe pyeloneprhtitis
- perinephric abscesses occur when micro-organisms from renal parenchyma or blood are deposited in soft tissues surrounding kidneys
What are the signs of chronic pyelonephritis?
- one or both kidneys contain gross scars
- not equal damage
- uneven scarring
- parenchyma shows interstitial fibrosis w/inflammatory infiltrate of lymphocytes and neutrophils
- contracted or dilated tubules
- colloid casts in the tubules
- concentric fibrosis about parietal layer
What do you SEE in the kidney with papillary necrosis?
- one or more pyramids, frequently both infected
- yellow necrotic tissue replaces pyramids
- portion of papilla can break off - produces recognizable calyceal deformity
- collecting tubules filled w/bacteria and polymorphonuclear leukcotyes
What is the typical pathogen if the UTI occurs via hematogenous spread?
-
Staph aureus
- frequently form abscesses
What are the common serogroups found in E.coli that cause UTIs?
- O1
- O2
- O4
- O6
- O7
- O8
- O75
- O150
- O18ab
When serotyping bacteria, what does the O mean
polysacchardie sugars in the outer membrane - part of LPS in outer membrane
What does the K encode when serotyping bacteria?
capusle antigen - can secrete capsule
encodes sticky glycoprotein
What does the H serotype mean
flagellar antigen - protein repeats put together
4 key virulence factors E. coli have:
- genes associated with adherence
- genes associated to resistance of serum bactericidal activity
- increased K antigen production (K1, K5, K12)
- with more capsule they have a bigger shell
- siderophore receptor (iroN)
What do P. fimbriae bind to?
- epithelial cell receptors containing globoseries glycosphingolipid
- P in fimbriae attach to the receptors
- the receptors make up the P blood group antigen complex on RBC and uroepithelial cells
What is special about E. coli with P. fimbriae
- resistant to neutrophil destruction
- induced increased signaling from TLR4
What do Type I fimbriae bind to? What inhibits their binding?
- mannose containing host epithelial receptors (uroplakin I and II)
- inhibited in the presence of free mannose
Prevention strategies for UTIs:
- vaccines in clinical trial
- regular urination
- good hygiene
- drink cranberry juice
What is the last line drug used for CRE - carbapenem resistant Enterobacteriacease
polymyxin B
What is the last line drug for VRE - vancomycin resistant enterococci
linezolid
What defines pyuria? Bacteriuria?
- pyuria = 10 more neutrophils
- bacteriuria = 10 to the 5th colony forming units
colony counts are much lower with complicated UTIs.
What is the most important first step in diagnosis of infectious disease?
accurate clinical history and physical exam
What does catalase differentiate between?
- Staph vs. Strep
-
staph is catalase +
- has enzyme capable of converting hydrogen peroxide to water & oxygen
What is the coagulase test used to differentiate between?
- Staph aureus vs. coag neg Staph
- staph aureus is ONLY coagulase +
- allows staph to breakdown collagen
- fibrogen clumps on staphylococcal cell
How do you distinguish between staph epidermidis and staph saprophyticus?
- use novobiocin sensitivity test
- S. saprophyticus is RESISTANT to novobiocin
- novobiocin inhibits DNA gyrase
What are the hemolytic properties of staph aureus?
of Staph saprophyticus?
- Staph aureus = beta hemolytic
- Staph saprophyticus = gamma hemolytic
Indole test
What does it look for?
What organisms are positive?
- looks at tryptophan
- E. coli is positive
- citrobacter is variable
Methyl Red
Looks at?
Which organisms are positive?
- glucose fermentation w/pH
- E. coli
- Citrobacter
- Proteus Mirabilis
- Klebsiella is variable
Voges test
looks at?
positive?
- looks at glucose fermentation w/neutral pH
- Klebsiella
- Proteus is variable
Citrate test
Used for?
positive organisms?
- determining which organisms use citrate for growth
- Klebsiella
- Proteus Mirabilis
What organism is indole positive and citrate negative?
E. coli
When do you use TMP-SMX?
When local prevalence is less than or equal to 20%
If not used in the last 3 months for UTI.
What is the first line treatment for S. saprophyticus?
- Amoxicillin/Clavulanate
When do you use fluoroquinolones for UTI?
- severe allergy to first line
- TMP-SMX used in last 3 months
- infection in area w/greater than 20% resistance to TMP-SMX
Nitrofurantoin
MOA
Activation
Contraindications?
- inhibits bacterial acetyl-coenzyme A
- activation dependent on urine acidity
- contra
- prengancy last 4 weeks
- impaired renal function
- men - doesn’t treat prostate
TMP-SMX
MOA?
Side effects
- sequential blockage of tetrahydrofolic acid pathway
- interacts w/warfarin through CYP450 and CYP2C9 system
Quinolone
MOA
Most active against?
Can’t be taken with?
- inhibits DNA gyrase and topoisomerase IV
- most active against aerobic gram negative bacilli
- can’t be taken with ANTACIDS
Describe the macConkey agar?
- Selective - only grows gram negative
- Differential
- lactose fermetation
What does P. Fimbriae allow for (related to cytokines?
Allows LPS to engage TLR4 more intensely. Increases downstream effects of IL-1 and TNF.
NF-kappaB and AP-1 are turned on.
Good test, besides gram stain, to tell between Saphrophytics and enterococcus.
Catalase test - staphrophyticus is catalase positive.
Why cant you use nitro in the last 4 weeks of pregnancy?
Could end up w/hemolytic anemia if individual has G6P deficiency.
Use 3rd gen cephalosporin.
Or beta lactam.
What are things that can make a UTI complicated?
- urinary catheters
- anatomical anomalies
- obstruction of urine flow
- poor bladder emptying
What are reasons for poor bladder emptying, that could cause complicated UTI
- caliculi
- tumors neurogenic disorders
- pregnancy
- prostatic enlargement
- uterine prolapse
- cystocele
Women with recurrent UTIs are more likely to have…
- maternal history of UTI
- first UTI before age 15
What does novobiocin do?
inhibits bacterial DNA gyrase in susceptible organisms.
Staph saprophyticus is resisant.
Citrobacter
gram + or - & shape
+ tests
Lactose fermenation?
- gram negative ROD
- for methyl red. Variable for indole.
- Yes - Slow lactose fermenter.
- Other
- use malonate.
- found in soil, water
- can accumulate uranium
Klebsiella
gram + or - & shape
+ tests
Lactose fermenation?
Urease?
Other?
- gram negative ROD
- voges and citrate. variable methyl red.
- yes - PINK ON MACCONKEY.
- Urease +
- immotile
- normal part of intestinal flora.
- 3rd leading cause of UTI
Proteus mirabilis
gram + or - & shape
+ tests
Lactose fermenation?
Urease?
Catalase?
Odor?
Other?
- gram NEGATIVE – ROD
-
methyl red & citrate
- variable voges.
-
methyl red & citrate
- NO LACTOSE fermentation.
- Urease +
- FISHY ODOR
- catalase +
- MOTILE - shows swarming on agars.
Staph saprophyticus
gram + or - & shape
+ tests
Lactose fermenation?
Urease?
Catalase?
Odor?
Other?
- gram positive
- Resistant to novobiocin.
- Urease +
- Catalase + (coagulase negative)
- 2nd leading cause of UTI
- gamma hemolysis
E. coli
gram + or - & shape
+ tests
Lactose fermenation?
Urease?
Catalase?
Odor?
Other?
- gram negative – ROD - encapsulated
- Indole and methyl red + (citrate negative)
- Catalase +
- Nitrite +
- EMB agar - green metallic - fast lactose fermenter.
- also on MacConkey
Pseudomonas aeruginosa
gram + or - & shape
+ tests
Lactose fermenation?
Urease?
Catalase?
Odor?
Other?
- gram NEGATIVE - rod
- AEROBIC
- NO LACTOSE
- catalase +
- MOTILE
- fruity odor
- blue-green pigment
Acinetobacter
gram + or - & shape
+ tests
Lactose fermenation?
Urease?
Catalase?
Odor?
Other?
- gram negative - occur in pairs
- oxidase negative
- non-motile
- may grow on MacConkey
- nitrate negative
- found in soil
Morganella
gram + or - & shape
+ tests
Lactose fermenation?
Urease?
Catalase?
Odor?
Other?
- gram negative
- Catalase +
- oxidase negative
- faculative anaerobe
- methyl red positive
How can you differentiate between staph saprophyticus and enterococcus, since both are gram positive?
- catalase test
- staph is catalase +
- enterococcus is catalase negative
What antibiotics do you use for UTI w/pregnancy?
- Nitrofurantoin up to last 4 weeks
- 3rd gen cephalosporin - ceftriaxone
- beta lactam
What is the most common type of nosocomial infection?
catheter related UTIs
What is an acute complication of pyelonephritis and when does it commonly occur?
- papillary necrosis
- occurs with:
- diabetes mellitus
- UT obstruction
- sickle cell disease
- analgesic abuse
What are some issues with papillary necrosis?
- sloughing - could lead to uretral obstruction
- intrarenal abscess
- perinephric absess - deposited into soft tissues surrounding kidneys
What is the pathognomonic feature of acute pyelonephritis?
- suppurative necrosis or abscess formation within the renal substance
What is seen with chronic pyelonephritis?
- one or both kidneys w/gross scars
- uneven scarring
- parenchyma has interstitial fibrosis with inflammatory infitrate of lymphocytes and neutrophils
- atrophy of tubular lining
- colloid casts
- periglomerular fibrosis
What quinolone is used against P. aeruginosa?
levofloxacin
