Renal Ettinger Flashcards
What is Carbamylated Hemoglobin?
(dissociated BUN that reacts with Hb) concentrations higher in dogs w/ renal disease (vs control) and higher w/ CRF vs ARF
What is GFR directly related to?
Functional renal mass
How is BUN made?
synthesis in liver via Ornithine cycle from catabolism of ammonia (from catabolism of endogenous and exogenous proteins)
Name 3 things that affect BUN.
Passive reabsorbed in tubules (greater extent when slow tubular flow (like with dehydration)
GI bleeding (increase nitrogenous compounds)
Drugs (increased catabolism with steroids, azathioprine), (decreased protein synthesis with tetracyclines)
How is creatinine made?
nonenzymatic breakdown product of phosphocreatinine in muscle, daily amount based on muscle mass
Which breed has higher creatinine?
Greyhounds (more muscle)
Describe the relationship btwn changes in BUN and creat.
Relationship of BUN or Crea concentration to GFR is a rectangular hyperbola; large changes in the early courses of renal disease cause only small increase in BUN/Crea vs small changes in GFR in advanced renal disease result in large changes
What does it imply when BUN and creatinine are increased?
Incr BUN & Crea implies that at least 75% of the nephrons are not functioning
What is cystatin C?
(small polypeptide protease inhibitor, freely filtered by glomeruli)
○ Filtered cystatin C - almost completely reabsorbed by proximal tubular cells and catabolized to AA
○ Produced at a constant rate = May serve as a marker of GFR
What can affect cystatin C?
inflammation or neoplasia
When does urinary concentrating ability lost?
When 66% of nephrons are lost
When does azotemia occur?
When 75% of nephrons are lost
When is it best to use the creatinine clearance?
When the patient is PU/PD but their BUN and creatinine are normal
Name agents that can be administered for a single injection to estimate GFR?
inulin, iohexol or Creatinine
When is dynamic renal scintigraphic methods with radioisotopes helpful?
When individual renal function information is needed
What is microalbuminuria an indication of ?
§ Humans: Early indication of vascular endothelial damage
Dogs/cats: 15-20% normal animals have an increase, unknown if results in progressive renal dz in vet med
What is the Bladder Tumor Antigen Test and what are problems with it?
latex agglutination dipstick test that detects glycoprotein antigen complex associated with bladder tumors in people
alse + occur w/ marked proteinuria, glucosuria, pyuria, hematuria
§ Good to differentiate neoplasia from normal dogs, but not good in animals with other LUT dz
What is the role of the water deprivation test?
tubular function test, used to decipher between DI vs psychogenic PD
When is the maximal stimulation of ADH release?
With 5% loss of BW!
What is the benefit of the gradual water deprivation test?
use to eliminate diagnostic confusion created by medullary wash out
○ Dogs with pyschogenic PD: Endogenous release of ADH, increased permeability of inner meduallary collecting ducts to urea and restoration of normal gradient of medulalary hypertonicity
Which electrolyte is good for pre renal vs renal disease?
Fractional excretion of Na: Pre-renal animals should have avid Na conservation!
What is the renal threshold for glucose in dogs and cats?
Renal threshold glucose – Cat 300, Dog 180 mg/dL
What ketones are noted on the dipstick?
○ Nitroprusside reagent (dipsticks) - Acetone < acetoacetate (NOT with beta-hydroxy)
What is the renal worm?
Dioctophyma renale
Which breed can get renal telangectasia?
Welsh Corgi
What is a caudate cells?
transitional cells w/ tapered edges that originate from the renal pelvis
Which casts are normal in low number?
Occasional hyaline and granular casts
What is a hyaline cast?
pure proteins precipitates (Tamm-Horsfall mucoprotein and albumin), dissolve in dilute or alkaline urine; Small numbers can be seen with fever/exercise; seen in diseases assoc. with proteinuria
What is a coarsely or fine granular cast?
degeneration of cells in other casts or precipitation of filtered plasma proteins; * suggestive of ischemic or nephrotoxic renal tubular injury
What is a fatty cast?
Fatty cast – type of coarsely gran cast – contain lipid granules; seen with nephrotic syndrome or DM
What is a cellular cast?
Cellular cast – white cell (pyelonephritis ), red cell cast (rare, fragile), renal epithelial cell cast (acute tubular necrosis or pyelonephritis)
What is a waxy cast?
○ Waxy cast – represent the final degeneration of granular casts (stable), suggest intrarenal stasis; brittle casts & often have cracks or sharply broken ends
Which crystals are seen in acidic urine?
Uric acid, CaOxalate, Cystine
Which crystals are seen in alkaline urine?
Struvite, CaPhosphate, Ca Carbonate, amorphous phosphate & ammonium biurate
What is the renal length on rads?
Renal size – L2 ratio (on VD) is 2.5 to 3.5 in dogs & 2.4-3.0 Cats
What is the “halo” sign in ultrasound of the kidney?
○ Ethylene glycol toxicity – renal hyperechogenicity “halo” sign correlated w/ onset of anuria
What is the significance of the medullary rim sign?
○ Medullary rim sign(echogenic line in outer zone of medular and paralleling corticomedullary junction) – ethylene glycol toxicity, acute tub necrosis, hyperCa, FIP, chronic tubulointerstitial nephritis; seen in normal cats (mineralized tubular basement membrane)
What is important for the number of glomeruli in the renal bx samples?
96% of samples contained > 6 glomeruli
What is the main complication with renal bx?
Hemorrhage (Severe hemorrhage in 10% dogs and 17% cats)
Can also see linear infarcts, and hydronephrosis
What is the definition of AKI?
· AKI → > 0.3 mg/dl increase in creatinine or >25% increase from baseline creat
What does RIFLE stand for and how it is used?
RIFLE (Risk; Injury; Failure; Loss; End-stage Renal Disease) classification based on:
1. Changes in creatinine and GFR (take into account preexisting renal disease) 2. Changes in urine output
àNot evaluated in vet med due to unknown baseline creat or urine output
What are the sections that can be effected to cause renal AKI?
o **Can affect any section: Tubular, Glomerular, vascular, interstitium, vessels
Tubular most common: Toxic or ischemic
What is the breakdown of bacterial infections that results in pylonephritis?
□ 74% = Gram negative → E. coli (37-45% of all UTIs)
□ 25-30% = Gram positive
□ Predisposing factors – endocarditis, discospondilitis and pyometra
What is the host of Leptospira interrogans Canicola?
Dogs
What is the host of Leptospira interrogans Icterohaemorrhagiae?
rats
What is the host of Leptospira interrogans Grippotyphosa?
vole, raccoon, skunk, opossum
What is the host of Leptospira interrogans Pomona?
cow, pig, skunk, opossum
What is the host of Leptospira interrogans Hardjo?
Cow
What is the host of Leptospira interrogans Bratislava?
rat, pig, horse?
What is the most common cause of AKI?
toxins!! § Dog → Ethylene glycol, NSAID, cholecalciferol, aminoglycosides
§ Cat → Ethylene glycol, Cholecalciferol, Lillies
What accounts for 70-75% of AKI?
Pre-renal + renal causes
What are the phases of AKI?
- Clinically silent (initiation)
- Extension Phase
- Maintenance Phase
- Recovery Phase
What happens during Clinically silent (initiation) of AKI?
- Clinically silent (initiation): Ischemic or nephrotoxins = if ID problem here and intervene improved outcome
What happens during Extension Phase of AKI?
- Extension Phase: Continued hypoxia and inflammation propagates damage
o Cortical structures (proximal tubule, Loop of Henle) are predisposed to toxic/ischemic since they receive 90% of renal blood flow and are highly metabolic
§ Decreased ATP = Impairing Na-K pump → Cellular swelling and death
§ Loss of brush boarder of apical and basal cells = Likely related to increased cytosolic Ca
o Intervention MAY NOT be helpful here :(
What happens during Maintenance Phase AKI?
- Maintenance Phase: 1-3 weeks, urine output may be affected
o Irreversible damage has occurred
o Urine resembles ultrafiltrate
o Increased/decreased urine output
What happens during recovery phase of AKI
- Recovery Phase: Increased urine output, +/- decreased urine sodium = May take weeks to months
o Extreme Na losses = Volume depletion (delay or stop renal recovery) = Need to replace Na and water
§ Na Loss →Decreased proximal and ascending loop henle sodium/potassium pump function due to reduced # of Na transporters and aquaporin-2 proteins
What are the 2 main mechanisms of decreased GFR in AKI?
• Main 2 mechanisms of decreased GFR → Hypoxia (intrarenal vasoconstriction) and tubular dysfunction
• Hypoxia: Poor medullar blood flow most to cortex, Intrarenal vasoconstriction (may be caused by altered endothelin/ decreased NO production - due to sublethal epithelial injury)
• Tubular Dysfunction:
o Obstruction by cellular debris (detached epithelial cells)
o Back-leakage of the tubules
Name other factors that leads to AKI.
ATP delpetion Increased intracellular Ca Reperfusion injury Oxidant injury Intracellular acidosis Phospholipase activation Protease activation Actin Cytoskeleton injury from energy depletion Disruption of cell-substrate attachment
When does mannitol help in AKI?
• ATP depletion (more AMP = energy deficit) causing Na/ K ATPase pump to stop functioning
o Causes Na/K concentration gradient imbalance
o Cell swelling à tubule obstruction, vascular congestion
§ Mannitol helps here (hemodynamic alterations, osmotic diuresis, scavenging hydrozyl ions)
What is the rationale behind using Ca channel blockers in AKI?
• Increased intracellular [Ca] causes mitochondrial swelling, uncoupling of oxidative phosphorlaylation and cell death
o Rational behind use of Ca channel blockers (diltiazem/verapamil) in ARF = Improve renal hemodynamics and stabilize cell membranes
What is essential for renal recovery?
Dependent upon sub-epithelial basement membrane, recovery of sublethally injured cells with recovery of realign (of polarity), migrate and regeneration (of renal cells), removal of necrotic cells/casts.
When there is renal damage what happens with fractional excretion of Na?
Renal damage = Na fractional excretion higher
Why are there false negative ethylene glycol test kits (esp in cats)?
Esp cats dt lower limit of detection of kit (50 mg/dl)
What infectious dz should be considered for AKI?
Lepto, Lyme, RMSF (oliguria RF, vasculitis, polyarthritis, meningitis, mild thrombocytopenia), Ehrlichia canis (glomerular damage)
In s study of dogs with with Hospital-acquire Acute Renal Failure (HARF), what are the most common causes?
□ Nephrotoxicant exposure 72% □ >7yrs old 69% □ chronic heart disease 41% □ preexisting renal disease 35% □ Neoplasia 31% □ Fever 28%
Anesthesia 14%
Volume depletion is VERY important
How are aminoglycosides nephrotoxins?
not metabolized, low molecular weight, water soluble–> urine excretions
□ Ionize and bind anionic sites on proximal tubule–> pinocytosis–> high intracellular concentration (10 X HIGHER)–> tubular epithelial cell damage
□ Increase risk of ARF with aminoglycosides: prolonged use >5days; elevated trough levels, preexisting renal dz, dehydration, hypo-kalemic, calcemia, magnesemia, acidosis
□ Reduce toxicity with less frequent dosing, toxicity more closely associated with [trough]
□ Monitor for proteinuria, casts daily (alert you prior to onset of azotemia)
What are occur if expired tetercyclines are given?
AKI
fanconi-like syndrome–> metabolites in mitochondria in proximal tubules
What happens in AKI from NSAIDs?
o NSAID: COX inhibition leading to Afferent arteriole constriction (reduced prostaglandins), healthy euvolemic minimal risk
§ Higher risk when trying to maintain renal blood flow and counteracting the effects of systemic vasoconstriction
§ COX 1 vs 2; both can be constitutive in kidney so no difference in risk of non-selective COX and COX-2 specific
□ Prognosis favorable if recognized early
What is a CVP?
Central venous Pressure
o CVP: 10 overhydrated
□ Challenge: 2-4 cm H20 rise euvolemic, >4 overhydrated, no change hypovolemic
What is normal urine output?
normal 1-2 ml/kg/hr
What is consider polyruia, oliguria, and anuria?
o Polyuria >2 ml/kg/hr
o Oliguria <1.0 ml/kg/hr
o Anuria-virtually no urine production
What medications can be used if concern about urine output?
Mannitol Furosemide Dopamine Fenoldopam (selective dopaminergic 1 agonist, renal artery dilation, inhibits N/K ATPase, angiotensin II, and ADH, dogs to have renoprotective effects in acute ischemic injury) Diltiazem
What are the average insensible losses per day?
Insensible: average 22 ml/kg/day, ie panting
What is the treatment for ethylene glycol?
4 methylpyrazole or ethanol
What are the typical ECG changes with hyperkalemia?
Bradycardia, tall tented T-waves, prolonged QRS, wide/absent P waves
What electrolyte abnormality is worse with ethylene glycol?
Hypocalcemia
What are the main uremic complications?
Hyperkalemia Metabolic Acidosis Calcium/ Mg Phosphorus Hypertension Hematological changes (anemia and thrombocytopathy) GI disorders Nutritional support Infections
In cats with AKI what did each increase unit of potassium show?
each unit increase in serum potassium, in mEq/L, there was a 57% decrease in chance of survival
What is associated with a negative prognosis in AKI?
Decreased urine output
NOT severity of azotemia
Is everity of azotemia associated with outcome in AKI?
NO!! Only Decreased urine output
What is the overall survival with infectious causes of AKI?
58-100%
What is the overall survival with toxic causes of AKI?
20-40%
Name several dz in which renal transplant is NOT recommended?
-Amyloidosis
-Pyelonephritis
+-Calcium oxalate obstructive disease
+- IBD (variable absorption of Cyclosporin)
-FeLV/ FIV+
-Cardiac disease
-HyperT4
-DM
-Neoplasia
What are the mainstays in immunosupresisve therapy in cats undergoing renal transplant?
Cyclosporine
Prednisolone
What are several long term complications of renal transplant in cats?
Rejection (acute and chronic)
Ureteral Obstruction (stricture)
Neuro signs (dialysis disequilibrium syndrome - Dt rapid osmotic shifts, hypertension?)
Hypertension (unknown reason, vasactive products in kidney?)
Infection (about 25%, bacterial , viral, fungal, protozoal)
Diabetes mellitus
Neoplasia
How long does a transplanted kidney work?
About 3 years in cats
What is the most common neoplasia that feline renal transplant cats get?
LSA
Neoplasia seen in about 10% cats
What syndrome has been reported in cats undergoing renal transplant and in kids?
• Hemolytic uremic like syndrome (3 cats: hemolysis, thrombocytopenia, thrombotic microangiopathy)
○ In kids this is caused by E. coli O157: H7 endotoxin
What is overall outcome of feline renal transplant?
Periop 25% mortality
Survival to discharge: 6 month survival 60-70% (time of highest mortality), 3 year survival-40-50%
What are the problems in canine renal transplant?
combination of immunosuppressive regimens
THROMBOEMBOLIC DZ!!!
What is CKD?
permanent reduction in # functioning nephrons
1. Kidney damage that has existed for at least 3 months (with or without ¯ GFR) 2. ¯ GFR by more than 50% of normal persisting for at least 3 months o Since renal compensatory hypertrophy and improvement in renal function may continue for up to 3 months following acute loss of nephrons
What is acute vs chronic kidney disease?
· “Acute” = potentially reversible (by resolution, adaptive compensatory enhancements, or combo)
· “Chronic” = irreversible and usually progressive loss of kidney function and/or structure, compensatory enhancements have already reached a nadir (about 3 months or longer)
o Clinical Signs: weight loss, polyuria, polydipsia, ¯ appetite, ¯ BCS, ¯ hair quality (3 months or longer)
o Documentation of kidney function (over 3 months): Progressive ↑ Creatinine
o Persistent proteinuria (> 3 months)
o Anemia is characteristic but NOT diagnostic
o Small kidneys (US): Loss of nephrons → replacement with fibrosis tissue
o Rare: Skeletal changes with renal osteodystrophy (esp within jaw)
Why i staging CKD important?
Helpful for establishing a prognosis and managing the patient
During what stage is PU/PD seen in CKD?
Stage 2-4
During what stage is proteinuria seen in CKD?
Stage 1-4
During what stage is UTIs seen in CKD?
Stages 1-4
During what stage is neproliths, ureteroliths seen in CKD?
Stages 1-4
What CS are seen in Stage 3-4 CKD?
Decreased appetite Dehydration Constipation Hyperphosphatemia Metabolic Acidosis Hypokalemia Anemia
During what stage is uremia seen in CKD?
Stage 4
What do you need to stage a dog/cat with CKD?
Need to obtain 2 or more serum creatinine readings when pet is FASTED and well hydrated over several weeks in order to use this staging
What is the threshold for Stage 2 CKD?
hreshold of stage 2 CKD → 1.4 mg/dL (dogs); 1.6 mg/dL (cats)
o Values btwn 1.4 mg/dL and upper RR should be able to concentrate their urine (1.030 (dog) and 1.035 (cat)) if normal kidney function
What are the substaging of IRIS CKD?
Magnitude of proteinuria and systemic blood pressure
When are animals considered to be proteinuric with CKD?
§ Proteinuric (P) when UPC > 0.5 (dogs) and 0.4 (cats)
When are animals considered to be nonproteinuric with CKD?
What are the stages of hypertension in CKD staging?
Stage 0
What is the prevalence of CKD?
1-3% cats and 0.5-1.5% dogs
What breeds of cats get CKD?
Maine Coon, Abyssinian, Siamese, Russian Blue, and Burmese cats
What happens with the incidence of CKD in dogs?
It increases with increasing age
Name two causes of CKD in cats that are related to virsuses?
FIV
SQ feline herpesvirus 1, calicivirus, and panleukopenia virus vaccines in culture have induced antifeline renal tissue antibodies → Could repeated vaccination play a role
What does renal bx reveal in dogs with CKD?
§ Biopsy Study (37 dogs)
o 58%: Chronic tubulointerstitial nephritis
o 28%: Glomerulonephropathy
o 6%: Amyloidosis
What does renal bx reveal in cats with CKD?
§ Biopsy Study (cats) o 70%: Tubulointerstitial nephritis o 15%: Glomerulonephropathy o 11%: Lymphoma o 2%: Amyloidosis
Name 3 dog breeds that get familial amyloidosis.
Shar-Pei, English Foxhound, Beagle
Name 5 breeds that get familial renal dysplasia.
Shih Tzu, Lhasa Apso, Golden Retriever, Norwegian Elkhound, Chow Chow, Standard Poodle, Soft Coated Wheaten Terrier, Alaskan Malamute, Miniature Schnauzer, Dutch Kooiker
Name a breed that gets familial fanconi syndrome.
Basenjis
Name 5 breeds that get familial glomerulopathy.
English Cocker Spaniel, Doberman Pinscher, Bull Terrier, Soft Coated Wheaten Terrier, Samoyed, Dalmatian, Bullmastiff, Newfoundland, Rottweiler, Pembroke Welsh Corgi, Beagle, Bernese Mountain Dog, Brittany Spaniel
Which breed gets Hereditary multifocal renal cystadenocarcinoma?
GSD
Name 3 breeds that get Polycystic kidney disease
Cairn Terrier, Bull Terrier, West Highland White Terrier
Which breed gets Reflux nephropathy with segmental hypoplasia?
Boxer
Which breed get renal Telangiectasia?
Pembroke Welsh Corgi
What cats get amyloidosis?
Abbysinian, Siamese, and Oriental Shorthair
Which cats get polycystic renal disease?
Persian and Himalayans
What are the prognostic factors for CKD in cats?
- Phosphorus and IRIS stage
- Magnitude of proteinuria
NOT hypertension in cats
What are the prognostic factors for CKD in dogs?
- Cats live longer with CKD than dogs
- Proteinuria: Risk of death associated with CKD increased by 60% for each unit of UPC above 1
- Baseline systolic BP
- BCS (fatter did better, similar to humans)
What are the 3 mechanisms of uremia?
These affect every organ system
- Disturbed excretion of electrolytes and water (more load on remaining nephrons)
- Decrease excretion of organic solutes (uremic toxins)
- Impaired renal hormone synthesis (*calcitriol, *EPO, prostaglandins, kinins, renin)
Are urea and creatinine considered uremic toxins?
No! But act as surrogate for systemic concentration other uremic toxins
What is known about calcitriol in dogs and humans with CKD?
calcitriol in dogs and humans with CKD may slow progression of kidney disease and prolong survival
What are several factors that can lead to impaired urine concentrationsin CKD?
increased solute load per surviving nephron (solute dieresis), disruption of the renal medullary architecture & countercurrent multiplier system, impaired response to ADH
What is the MOA of anemia in CKD?
short RBC life, nutritional abnormalities, EPO inhibitors in uremic plasma, blood loss, myelofibrosis, EPO synthesis (renal peritubular capillary endothelial cells and interstitial fibroblasts likely sources) (a relative vs absolute deficiency in EPO levels)
What is the MOA of thrombocytopathic in CKD?
abnormal PLT function (diminished PLT thromboxane A2 production, abnormal iCa mobilization, increased intracell cAMP) biochem changes in blood itself
What was found in a • Prospective longitudinal study
○ Determine if cats in nonazotemic stage of CKD have increased PTH (as a compensatory mechanism to maintain phosphorus in RR)?
- Plasma PTH was significantly increased in cats that developed azotemia compared to cats that remained nonazotemic
- PTH increased prior to changes in plasma Ca or Phos
- Moderate positive association btwn plasma calcitriol and PTH was noted
- Plasma PTH was associated with: age, urea, creat, total Ca
- Suggests that renal secondary hyperPTH can develop prior to azotemia in cats (even in the absence of hyperP or hypoCa)
What electrolyte is directly linked to increased mortality in humans, cats and dogs with CKD
phosphorus
What is the self perpetuating cycle with potassium in CKD?
excessive urinary K loss and whole body K depletion that is likely to further decrease renal function
Marked hypoK – PU bc decreased renal responsiveness to ADH
What is the MOA of proteinuria resulting in progressive CKD?
mesangial toxicity, tubular overload & hyperplasia, toxicity from specific proteins, MCP-1 (proinflammatory molecules, monocyte chemoattractant protein-1); overload of lysosomal degradative mechanisms
What are risk factors for ACUTE decline in renal function?
Volume depletion urinary obstruction Nephrotoxic drugs ABX NSAIDs ACEi and Angiotensin II receptor blockers IV contrast
What are risk factors for LONG TERM decline in renal function?
Active renal dz Hypertension Inappropriate diet/nutrition Neprholithiasis/ureterolithasis Proteinuria UTI
What is the link with CKD and FIV?
cats with CKD were significantly more likely to have positive test results for serum antibodies against FIV gp40 than cats without CKD
What is recommended for phos in CKD diets?
Phos restriction for Dogs & Cats w/ stage 2,3,4 of CKD
What is true about dogs that were fed a renal diet?
risk of developing a uremic crisis was reduced by 75% in dogs fed renal diet vs adult maintenance diet
What are the current recommendations for feeding renal diets to cats/dogs?
§ Cats – CKD stages 2-4; Dogs 3-4; **Stage 2 CKD in dogs not evaluated critically
§ Any Stage II patient with P exceeding 4.5 mg/dL may benefit from dietary therapy
What is a potential side effect with AlOH on RBCs?
Microcytosis
What is the number one SE of hormone replacement for anemia in CKD?
1 Neutralizing anti-EPO Ab hypertension, seizures reported
What is a potential complication with using lanthanum based phos binders (sevelamer)?
§ Can have effects on clotting dt vit K def
What treatment has been shown to have an equivocal benefit in cats but great benefit in cats?
Calcitriol therapy
When is calcitriol therapy required in dogs? Why is it important?
confirmed the value of calcitriol in reducing mortality in dogs with CKD stages 3 & 4
§ Improvement in appetite, more BAR, more active, longer lifespans
Name factors that result in normal micturition in urinary tract that defend against microbes..
Adequate urine volume
Frequent voiding
Complete voiding
Urinary continence
Name factors that result in anatomic structures in urinary tract that defend against microbes.
Urethral high pressure zones Surface characteristics or urothelium Ureteral peristalis Prostatic sections (antibacterial fraction and Ig) Length of urethra Ureterovesical flap valves Ureteral peristalsis Glomerular mesangial cells: Possible phagocytic and antigen presenting functions Extensive renal blood supply and flow
Name factors that result in antimicrobial properties of urine in urinary tract that defend against microbes.
Extreme high and low pH Hyperosmolality High urea concentration Organic Acids Low MW carbohydrates Tamm-Horsfall mucoproteins Host Defense peptides (defensins)
Name factors that result in systemic immunocompetence factors in urinary tract that defend against microbes.
Cell mediate immunity
Humor-mediated immunity
Name factors that result in mucosal defense barriers in urinary tract that defend against microbes.
Antibody production
Surface layer of glycoaminoglycans
Intrinsic mucosal antimicrobial properties
Exfoliation of urothelial cells
Bacterial interference by commensal microbes of distal urogential tract
Mucosal innate immunity: Toll-like receptors
What are microbial factors to enhance virulence in E. coli?
§ O-antigen (outer polysaccharide, marker of virulence in humans)
§ K-antigen (capsule, may inhibit phagocytosis and complete mediated bactericidal activity; increase resistance to inflammation favors persistence of bacteria in tissue)
§ Adhesive Fimbriae (pili; proteinaceous filamtous organelles that protrubed form bacterim; may enhance capacity to adhere to urothelium (p-fimbriae)
§ Hemolysin (Increases amount of free iron available to bacteria; tissue damage)
§ Aerobactin (iron binding protein)
§ R-plasmids (promote antibacterial resistance)
§ Resisatnce to bactericidal activity
§ Short generation time in urine
Which bacteria make urease and what is the role?
Proteus/ Staph/ Klebsiella (some)
Hydrolosis of urea to ammonia (causing epithelial damage)
Promote Struvite (magnesium ammonia phosphatase) formation
What are the most common micrboes isolated from UTIs?
○ 33-50% E. coli
○ 25-33%: G+ cocci: Staph/ Strep/ Enterococcus
□ Cats: Staph felis unique pathogen
○ Others: Proteus, klebsiella, Pasteurella, Pseudomonas, Corynebacterium
What uropathogen is unique to cats?
Staph felis
What is the breakdown of isolates in urine cultures (numbers)?
Single pathogen 75%, 2 pathogens 20%, 3+ 5%
What cultures are used for urine?
Blood agar-support growth
MacConkey-colony morphology
What is the biggest risk factor for UTI when a U cath is in place?
The duration that the u cath is in place
What antibiotics should be used as “first-line” in UTIs?
Amoxi, cephalexin, TMS (consensus says TMS and Amoxi only)
What is defines as a complicated UTI?
intact dogs, most cats, animals with identified predisposing factor (DM, Cushing’s dz, hypert4, CKD), upper urinary infection
What is a relapse in a UTI and what are potential causes?
Recurrence of UTI with SAME bacteria
◊ use of an inappropriate antimicrobial agent
◊ administration of an appropriate antimicrobial agent at an inappropriate dosage, frequency, or duration
complicating factors such as a permanent breach in urinary tract defenses, particularly those that allow a nidus of infection to form and prevent complete penetration of drugs
What is a reinfection of a UTI?
Recurrence of UTI with DIFFERENT bacteria within 6 months of prior UTI
What is defined as recurrent UTI?
3 or more UTIs in 12 months
What is a superinfection?
Infection with new bacteria while on ABX for previous UTI
What is a refractory UTI?
Persistence of + UC result during treatment