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Kidney Lect 15

Urinary Tract Infections

Second most common cause for prescription of antibiotics UTIs
Epidimiology of UTIs: gender, age Most infections are limited to the lower urinary tract (bladder only) and occur 30 times more often in young women than young men. However, the incidence in men rises dramatically after age 50
Pathogenesis of UTIs: what is the most common way that bacteria arrive at site of infection? 1) ascending route via urethra most common (95%); 2) hematogenous (blood-->kidney-->bladder) rare; associated with endocarditis (S. aureus, tuberculosis); 3) Direct connection or fistula between bowel and bladder (rare)
What are the most common agents associated with ascending infection via the urethra? E.coli, Proteus, enterobacter
Microbial factors promoting risk of UTI 1) colonization 2) Adherence factors of bacteria (E.coli adhere to urothelial cells, proteus and providencia adhere to lumen of catheter material) 3) Inoculum size 4) virulence of micro-organism
Why are UTIs more common in diabetes? High glucose concentration-->support growth of microorganisms
What mechanical factors can decrease risk of UTI? Dilution and flow of urine (static urine-->more growth); length of urethra (female tract shorter than male tract)
What interference factors can decrease risk of UTI? normal bacterial flora (meatus) prevents overgrowth of pathogenic flora
What chemical factors can decrease risk of UTI? 1) osmolality and pH of urine, 2) prostatic fluid
What immune mechanism can decrease risk of UTI? 1) anti-adherence mechanisms in the bladder 2) urinary immunoglobulins 3) mucosal antibacterial actvitiy
What clinical risk factors can result in development of an UTI? 1) alteration of colonizing bacteria 2) retrograde introduction of bacteria 3) urinary stasis 4) nutrients-diabetes mellitus 5) foreign materials
How can colonizing bacteria be altered, leading to UTI? 1) antibiotics / spermicides 2) vaginal atrophy (age)
What things can cause the retrograde introduction of bacteria, leading to an UTI? Sex, insertive rectal sex, inserting items in urethra, insertion of foley catheter, cytoscope
What things can cause urinary stasis, leading to an UTI? neurogenic bladder (MS, paraplegia), reflux into ureters (pregnancy), congenintal anatomical abnormalities, obstruction (prostate hypertrophy (age), stones, tumor)
What things can cause alterations in nutrients, leading to an UTI? diabetes mellitus-->glycosyuria (and neurogenic bladder)
What foreign materials can lead to an UTI? stones, stents, catheters
Asymptomatic bacteriuria: characteristics isolation of a specified quantitiative count of bacteria, an appropriately collected urine specimen, obtained from person without symptoms or signs referable to UTI
Dysuria discomfort when voiding, burning sensation
What can cause dysuria? atrophy of vaginal tissues (post menopausal), vaginitis (no pyuria), candida (overgrowth), trichomonas (STI), urethritis--pyuria <100 cfu/ml (chlamydia, neisseria, gonorrhoeae, HSV)
Cystitis symptomatic BLADDER infection; characterized by frequency, urgency, dysuria, or suprapubic pain; pyuria; bacterial presence >10^3-5 cfu/mL
Acute uncomplicated cystitis in a woman with normal genitourinary tract
Complicated cystitis Everything else (besides woman with normal genitourinary tract): recurrent cystitis, abnormalities in GU tract; in male, pregnant women, children
yelonephritis infection of kidney parenchyma characterized by CVA tenderness, fever (often), sometimes with secondary bacteraemia (urosepsis)
Complicated UTIs (cystitis or pyelonephritis) symptomatic urinary infection in individuals with functional or structural abnormalities of the urinary tract; UTIs in men, pregnant women, children; cystitis or pyelonephritis other than in healthy women; prostatitis
Leukocyte esterase rapid screening test for detecting pyuria (via dipstick)
Patients with symptoms and negative Leukocyte esterase should... have urine microscopic examination for pyuria
Urinary nitrate nitrite formed when bacteria reduce the nitrate that is normally found in the urine; false negatives common, but false positives are rare (high ppv?)
How can you distinguish between bladder bacteria (pathogens) from urethral bacterial (contaminants) Bladder urine is sterile while distal urethra is not sterile
A true UTI is accompanied by what findings (microscopic)? Microscopy: pyuria (>10 leukocytes/mm3 of uncentrifugated urine) unless catheter in place (threshold higher) + lack of epithelial cells (indicates contamination
A true UTI is accompanied by what findings (microbiological)? Positive culture is: 1) only one bacterial species 2) classic is >10,000 cfu/mL 3) with symptoms, threshold (90% chance of infction) is >1,000 cfu/mL
Do NOT culture urine unless ... indicated AND abnormal UA
Asymptomatic bacteriuria in healthy premonopausal women: Bacteriuria increases risk for ____ but is not associated with ____; treatment ____ frequency of symptomatic infection; screening + treatment ...? symptomatic UTI; adverse outcomes; neither decreases frequency of symptomatic infection nor prevents further episodes of asymptomatic bacteriuria; screening + treatment in absence of symptoms NOT indicated
Asymptomatic bacteriuria in pregnant women inceases the risk of... 1) pyelonephritis during pregnancy (20-30x) 2) premature delivery 3) low birthweight infant 3) group B strep puts newborns at risk for meningitis
Asymptomatic bacteriuria in pregnant women: should it be screened + treated? Treatment decreases risk of complications, so screening for bacteriuria by urine culture is indicated at least once in early pregnancy
Asymptomatic bacteriuria in elderly institutionalized subjects: treatment? Screening? Not recommended since treatment does not decrease rate of symptomatic infections, improve survival, or decrease chronic GU symptoms
Asymptomatic bacteriuria in patients with indwelling catheters: screening? Treatment? antimicrobial therapy NOT associated with decreased rate of symptomatic infections but IS associated with recurrence with more resistant organisms-->no screening or treatment
Screening of asymptomatic people for bacteriuria is only appropriate to prevent adverse events in... 1) pregnancy (gp B streptococcus) and 2) prior to urologic surgery-manipulation that can facilitate retrograde introduction
Acute uncomplicated UTI (cystitis): symptoms 1) dysuria, frequency, urgency 2) initial and terminal hematuria 3) suprapubic discomfort 4) low-grade fever may occur
Acute uncomplicated UTI (cystitis): exclude what other causes? STIs and vaginitis
Acute uncomplicated UTI (cystitis): diagnosis dipstick or microscopy (nitrite positive + positive LE/WBC); culture (not usually necessary; carefully obtained clean catch; 10000-100,000 cfu/mL, monoculture)
Acute uncomplicated UTI (cystitis): common bacterial causes E.coli (80-90%), Staph. saprophyticus (5-15%), proteus, and klebsiella species
Therapy for acute uncomplicated UTI in non-pregnant adult female without anatomic/functional/immunological abnormalities Recommended course: TMP-SMX (bactrim) first choice (3 days); fluoroquinolones as second choice (3 days); nitrofurantoin (7 days): NOT FOR PYELONEPHRITIS since it DOES NOT PENETRATE KIDNEY
What are the resistances of E. Coli to the most common antimicrobials? Resistance to E. Coli varies (amoxicillin 30%, 1-20% nitrofurantoin, 5-15% to TMP-SMX (bactrim), 5-15% ciprofloxacin)
Therapy for recurrent uncomplicated cystitis 1) obtain UA and culture
Therapy for recurrent uncomplicated cystitis in the case of relapse (<2 weeks between episodes) Non-compliance-urge patient to take Abx, think of cheaper alternative; Abx resistance, use sensitivities to prescribe alternative antibiotic; Uneradicated focus (stone), consider urologic evaluation
Therapy for recurrent uncomplicated cystitis in the case of reinfection (may be same or different organism in an interval >2 weeks) 1) hygiene/wiping instructions 2) post coital, consider prophylactic antibiotic 3) vaginal atrophy: application of topical estrogen 4) post void residual: prostetic devices, reconstructive surgery)
Therapy for complicated UTI (everyone/thing else): what etiologies should you consider? Kidney involvement with 2nd bacteraemia in a child, male, pregnant female; abnormality in anatomy, function, immunology; urologic procedure; catherization; unusual or resistant organisms; hematogenous route
Acute pyelonephritis: what is the most common cause? How should you approach treatment? mostly an ascending infection usually caused by E. Coli; HOWEVER, do obtain urine culture and if hospitalized obtain blood cultures
Acute pyelonephritis in mild to moderately ill patients: treatment? TMP-SMX (bactrim), cefuroxime or fluoroquinolone; patients usually improve in 48-72 hours; treat for 1-2 weeks
Acute pyelonephritis in severely ill patients and life-threatening urosepsis: treatment? Ampicillin + aminoglycoside; IV therapy until patient afebrile for 48-72 hours; treat for 2 weeks
In the case of acute pyelonephritis, what should you do if fever persists and in ALL CHILDREN AND MEN? Renal US, CT scan or MRI +/- IV pyelogram (IVP): look for perinephric absecess + exclude urinary obstruction
Therapy for cystitis in males: what etiologies should you consider? young men (rare in men under 50): anatomic abnormalities, anal insertive sex, toys. Older men: calculi, enlarged prostate/obstruction, chronic prostatitis
Most common cuase of relapsing UTI in males is... chronic bacterial prostatitis
What are the most common causes of UTIs in men (other than cystitis and pyelonephritis)? Urethritis (gonorrhea, chlamydia, ureoplasma), prostatits (gram negative rods, enterococci, staph. aureus)
How do you diagnose acute prostatitis? fever, chills, dysuria, pain, marked local tenderness upon palpation of prostate
How do you treat acute prostatitis? excellent penetration by most antibiotic classes--easily cured
What are the complications of acute prostatits? prostatic abscess and chronic prostatitis
Chronic prostatits: diagnosis chronic pain, dysuria, recurrent UTIs (same organism)
Chronic prostatits: therapy poor antibiotic penetration (difficult to treat) due to biofilm/calculi; prefered agents are fluoroquinolones and TMP-SMX
What (3) factors make catheters increase the risk of UTI? conduit (both in external and internal surfaces), foreign body facilitating biofilm formation, incomplete emptying of bladder (static urine)
What are the most common agents involved in catherized patients? Providencia stuartii, proteus, E. coli, pseudomonas
What are the complications associated with catheteried patients? bacteriuria universal, pyuria common from bladder irritation, cannot diagnose UTI unless: fever (cured often with cath change alone)+ pyelonephritis
How do you prevent catheter-related UTIs? avoid catheterization (early removal, replace catheter frequently, intermittent cath far superior); avoid extrinsic contamination of system (closed catheter drainage)
Almost all candiduria occurs in ... patients with indwelling catheters
Candida in the urine: risk factor? treatment? Risk factor is PRIOR antibiotics; removal of catheter-->clearance of most candiduria; oral fluconazole or amphotericin B bladder irrigation eliminate candiduria short term (no more effective than no therapy)
What are the only indications for treatment of asymptomatic candiduria? 1) urinary tract obstruction (fungus ball), 2) neutropenia 3) renal transplant recipient 4) urologic procedure in enxt 48-72 hours
Sterile pyuria: treatment Antibiotic pre-treatment kills bacteria (culture negative); non-infectious cause (interstitial nephritis or cystitis); organisms that don't grow on commonly used culture media
Genitourinary tuberculosis: tissues affected; pathophysiology Hematogenous seeding can occur in cortex and medulla; granulomas-->caseation-->erosion into collecting system-->further spread into ureter, bladder, prostate
Genitourinary tuberculosis: diagnosis high index of suspicion: clinical disease mostly insidious with dysuria, renal functional defects. 1) PPD skin testing/interferon release assay 2) imaging 3) culture M. tuberculosis from urine, early AM sample (concentrated urine), multiple urine samples)
Created by: karkis77



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