UTI Micro Flashcards
What are the major defenses of the Urinary tract?
- Chemistry
- Flow
- IgA (adaptive immune)
- Different surface proteins of epithelial than GI tract
What are the chemistry defenses of the urinary tract?
- pH
- Lysozyme- breaks down peptidoglycan
- Lactoferrin– sequesters iron from bacteria
What are the major threats to the urinary system?
- Microorganisms
- Blocked/decreased flow
- Hematoganous threat from another anatomical location
What is the cause of cloudy urine in a UTI?
WBC’s
Bacteria
What are the Sings and sx’s of cystitis?
Sudden onset pain Dysuria Frequency/urgency Cloudy urine Orange or red urine Fever/n Back pain
What is an uncomplicated UTI?
Structurally or Neurological normal urinary tract
What are some examples of complicated UTI?
- Persistent infections
- Foreign bodies like calculi and catheters
- Obstruction
- Immunosuppression
- Renal failure
- Renal transplant
- Urinary retention from neuro dz
What are the bacterial causes of UTI’s?
- E. Coli 80%
- Staph saprophyticus 10%
- The rest are 10%:
3a. Enterococcus spp
3b. Klebsiella
3c. Citrobacter spp
3d. Proteus mirabilis
Is the E. Coli that causes Bloody diarrhea and watery diarrhea cause UTI’s?
no
- Those are EHEC and ETEC
- UPEC is what causes UTI’s
What does UPEC stand for?
Uropathogenic E. Coli
What percent of women who get UTI’s have them reoccur?
25-30%
What is the most common nosocomial infection?
Catheter related UTI’s
accounts for 40%
Who is at less risk for UTI?
Children and men
Why would a child get a UTI?
Sexual assault
Atomic or functional abnormalities
Why would a man get a UTI?
Usually UT abnormality
Obstruction
Enlarged prostate
Can lead to prostitis or epidydimitis
What the sx’s of pyelonephritis?
Flank pain Fever Nausea Dysuria Vomiting Malaise
1/4 mil cases/year
Which patients have risk factors for papillary necrosis (complication of pyelonephritis)?
in DM pts
Obstruction
Sickle cell
Analgesic abuse (can happen without infection)
Necrotic tissue can slough off and block downstream
What are some gross anomalies with pyelonephritis?
- Enlarged
- Discrete yellowish raised abscesses
- Histo- Suppurative necrosis
How does one diff between chronic glomerulonephritis and chronic pyelonephritis?
In Chronic pyelonephritis the kidneys are not scared evenly bilaterally.
What is periglomerular fibrosis?
Concentric fibrosis about the parietal layer of the Bowman’s capsule
What are some characteristics of pyelonephritis?
- Colloid casts
- Periglomerular fibrosis
- Dilated tubules
- Atrophy of endothelial lining
- Parenchymal with interstitial fibrosis and inflammatory infiltrates
Can one see necrotic papilla on a plain film?
Yes
Radiopague
What is common sight of abscesses for pts with Staph Aureus endocarditis?
Kidneys
Via Hematogenous spread
Gram - rarely spreads this way
What do O K and H stand for in serotyping of bacteria?
O- Polysaccharide sugars
K- Capsule ag
H- Flagellar ag
Are the serotypes of E Coli that cause cystitis vs pyelonephritis the same?
Nope
Genetically distinct
What are some virulence factors for E coli?
Adherence Resistance K ag Siderophore receptor Toxins and factors
What is main virulence factor for E coli?
P Fimbriae
- Binds to globoseries glycophingolipid found on uroepithelial cells
- Resists neutrophil destruction
What does Type 1 fimbriae bind to?
mannose containing host epithelial receptors
- Uroplankin 1 and 2
- however mannose sensitive because they bind so strongly to mannose that bacteria doesn’t infect us with excess mannose in urine
What is needed in order for E coli to cause cystitis?
Type 1 Fimbriae
What is the MOA of Linezolid?
Binds to 23S subunit of the 50S subunit and inhibits protein synthesis
What are the 50S inhibitors?
CCEL= Sell C= Chloramphenicol and clindamycin E= Erythromycin (macrolides) L= Linezolid
All static but linezolid can be cidal
What are the 30 S inhibitors ?
AT
A=Aminoglycosides (cidal)
T= Tetracyclines (static)
What is the mnemonic for 30s and 50s inhibitors?
buy AT 30, CCEL (sell) at 50
What are the common nosocomial infections pathogens? Treatment?
- E. Coli
- K. pneumoniaie (Carbapenum resistant enterobacteriaceae (CRE)
- VRE- vancomucin resistent enterococci
Linezolid
What is needed for bacteriuria?
> 10^5 colony forming units per ml
What is pyruia?
10 or more neutrophils per high power field of unspun, voided midstream urine
How does one diff between staph and enterococcus?
Catalase test
Staph is positive
How does one diff between staph a and staph saprophyticus?
Coagulase test
SS is negative
What is a positive catalase test?
Oxygen bubble production
- Some bacteria protein H202 and O2- and thus need enzymes to break this down and protect themselves.
- Catalase converts these reactive species to H20 and O2.
What is coagulase?
Free and bound
- causes bacteria to clump together with fibrinogen which results in a precipitation
How does one diff between staph epi and staph saprophyticus?
Novobiocin test
Epi is sensitive
Sapro is resistant
What does novobiocin do?
Inhibits bacterial DNA gyrase in susceptible organisms
What is unique about E coli in terms of Indole, citrate, MR and VP tests?
only enteric organisms that is both always Positive for indole and negative for citrate
What are the first line treatments for UTIs? Contraindicated?
- Nitrofurantoin–> with suspected pyelonephritis as it has poor affect there
- TMP-SMX–> >20% local resistance and used in last 3 months
What are the alternative treatments for UTIs?
- Fluoroquinolones
2. Amoxicillin/clavulanate (augmentin)
What is first line treatment for staph saprophyticus?
Augmentin
What is the MOA of Nitrofurantoin?
Inhibits bacterial acetyle-coenzyme A
- interferes with organisms carb metabolism
- disrupt cell wall formation too
How does nitrofurantoin get activated?
By bacteria flavoprotein
Thus its a prodrug
30-40% excreted in urine unchanged
Can pregnant people take nitrofurantoin? Renal pts?
no
- it crosses the placenta and distributed through breast milk
- accumulates and can be toxic in renal pts
What do sulfonamides inhibit?
pteridine synthetase
- Inhibits Pteridine + PABA from forming into dihydropteroic acid
What does trimethoprim inhibit?
Dihydrofolate reductase
- inhibits production of tetrahydrofolic acid from dihydrofolic acid
What else can Bactrim be used for?
- Acute bronchitis
- Otitis media
- Pneumocystis jirovecii pneumonia
- Traveler’s diarrhea
- Shigellosis
- UTI
What does Bactrim interact with that could be fatally bad?
CYP450 and CYP2C9
What is the MOA of Quinolones?
Inhibits DNA gyranse and topo IV
- contraindicated while using antiacids
- contraindicated in people taking iron supplements
What is potent enough quinolone to fight again P aeruginosa?
Levofloxacin
What are the current uses of quinolones?
most active against aerobic gram-negative bacilli, particularly members of the family Enterobacteriaceae and Haemophilus spp., and against gram-negative cocci, such as Neisseria spp. and Moraxella (Branhamella) catarrhalis. Relative to nalidixic acid, the fluoroquinolones also have additional activity against gram-negative bacilli, such as P. aeruginosa and against staphylococci.
