Renal - UTI Flashcards
Define upper and lower UTI by anatomical structures
o Upper UTI: Kidney to ureter at vesicoureteric junction
o Lower UTI: Urinary bladder/ Prostate/ Urethra
Define complicated vs uncomplicated UTI
Uncomplicated:
Patient without structural and functional abnormality or underlying condition
No risk of failing standard therapy
Complicated:
Patient with structural and functional abnormality or an underlying condition that increases the risk of infection or failing therapy
Pathogens that typically cause community-acquired UTI
Facultative aerobes from intestinal tract
85% E.coli
Others:
- Proteus
- Klebsiella spp
- Entercoccus
- Staphylococcus saprophyticus
Pathogens that cause nosocomial UTI
50% by E.coli
Others:
- Pseudomonas
- Providencia
- Citrobacter
- Coagulase-negative staphylococcus
- Serratia
- Enterobacter spp.
(in the hospital, a CCP PEES and gets infected)
Risk factors for complicated UTI
All causes of neurogenic bladder, mechanical bladder outlet obstruction (e.g. strictures, stones, clots…etc), vesicoureteral reflux
Altered immunity: DM, immunocompromised or pregnancy, sepsis…etc
Recent hospitalization (nosocomial infections) or presence of indwelling catheter/ iatrogenic damage to urinary tract
(Males are less prone to UTI and thus it is usually considered complicated when present)
Define recurrent UTI
≥ 2 infections in 6 months or ≥ 3 infections in 12 months due to reinfection or relapse from a persistent focus
Difference between reinfection and relapse in recurrent UTI
Reinfection: infecting strain is different from original and the recurrence occurs > 2 weeks of the completion of treatment for original infection
Relapse: infecting strain is the same from original and the recurrence occurs ≤ 2 weeks of the completion of treatment for original infection
Sources of bacterial persistence in recurrent UTI/ correctable bacterial persistence causing UTI
Infections:
- Struvite stones/ mixed kidney stones,
- infected atrophic kidneys/ renal abscesses
Anatomical/ developmental defects:
- ureteral stump after nephrectomy,
- medullary sponge kidney/ Cacchi-Ricci disease (birth defect in renal tubules)
- papillary necrosis (uncontrolled DM, Analgesics abuse)
- Urachus adnormalities (duct between bladder and umblilcus): urachal cyst, urachal diverticulum
- Urinary fistulas e.g. vesicovaginal/ vesicocolic fistulas from Bladder CA
Presence of bacteria and WBC in urine must equate to UTI. True or False. Why
False
Bacteriuria and pyuria does not mean UTI
Bacteriuria: UTI or colonization or contamination of sample
Pyuria: inflammatory process in urinary tract
DDx of pyuria
Inflammatory condition in urothelium:
UTI, Urolithiasis, Malignancy, Tuberculous infection
Classical triad of symptoms in acute pyelonephritis
(i) Fever ≥ 38.0oC
(ii) Chills
(ii) Loin pain or tenderness
Risk factors of UTI
Female sex - Shorter urethral length
Lack of circumcision - foreskin bind to uropathogens, partial obstruction
Vesicoureteral reflux (VUR) (most common in children UTI due to incompetence of UV Valve)
Urinary obstruction - urine stasis
Bladder and bowel dysfunction - incontinence, abnormal voiding
Urinary instrumentation - Bladder catheterization
Sexual activity
Causes of urinary obstruction
- Anatomical: Posterior urethral valves/ Ureteropelvic junction obstruction
- Neurological: Myelomeningocele, neurogenic bladder
- Functional: Bladder and bowel dysfunction
read full flashcards at urinary obstruction WCS
Risk factors for recurrent UTI in pre-menopausal women
- Genetics - Increased susceptibility to vaginal colonization with uropathogens and bacterial adherence
- Pelvic anatomy - Urethra-to-anus distance
- Sexual activity - Frequent sexual intercourse, New sexual partners, Diaphragm or spermicide use
- Drug - Recurrent antimicrobial use (alteration of vaginal flora)
Risk factors for recurrent UTI in post-menopausal women
- Estrogen deficiency - atrophic vaginitis
- Pelvic organ prolapse/ cystocele - Urinary incontinence
- Indiscriminant use of antimicrobials
- Large residual volume post-void (decreased sensitivity to bladder volume due to aging)
- History of recurrent UTI
Viruses that cause UTI
- Adenovirus
- Enterovirus
- Echovirus
- Coxsackievirus
Fungi and parasites that cause UTI
Fungi:
* Candida
* Aspergillus
* Cryptococcus neoformans
Parasites:
- filariasis,
- trichomoniasis,
- leishmaniasis,
- malaria
- schistosomiasis
Normal defense mechanisms against UTI
- Normal flora: lactobacilli in introitus, vagina and periurethral area produces low pH
- Host immunity: cervical secretory IgA
- Urine: anterograde flow, pH and Tamm-Horsfall protein to prevent bacteria adherence
- Bladder: normal emptying, exfoliation of urothelial cells, immune receptors on superficial urothelial cells to recognize LPS and activate local inflammation
Factors that can alter normal defense mechanisms against UTI
Normal flora: Altered by antimicrobial
Urine: Altered by urinary tract obstruction
Bladder: Altered by urinary tract obstruction, neurogenic bladder, indwelling catheter, vesicoureteral reflux and bladder diverticulum
Genetic factors that increase risk of UTI
- Genetically determined vaginal cell susceptibility to bacterial adherence
- Lewis blood group: affects cellular fucosylation and bacterial adherence
Lewis blood groups asso. with increase risk of UTI (not important)
Le a-b- and Le a+b- = recurrent UTI
Le b- = premenopausal acute pyelonephritis
4 virulence factors in uropathogens
- Bacterial adhesins (fimbrial not afimbrial)
a) Fimbrial adhesins (pili)
- Type 1 (mannose-sensitive) pili for E. coli, acute cystits
- Type P (mannose-resistant) pili, acute pyelonephritis
- Type S pili, cystitis and nephritis
b) Afimbiral adhesins - Toxins: hemolysin HlyA
- Urease: urea to ammonia increase pH
- IgA inactivating protein
Routes of UTI spread (3)
- Ascending spread (most common)
- Hematogenous spread
• Secondary infection from extrarenal source of bacteremia e.g. Renal abscess from septic emboli, Genitourinary tuberculosis (TB)…etc - Direct inoculation from neighboring suppurative infections
List 7 Lower urinary tract symptoms (LUTS) (Mnemonics: FUN DISH) **
Storage: Frequency, dysuria Urgency Nocturia Urinary incontinence
Voiding: Post-micturition symptoms: Dribbling, retention Intermittent and weak stream Straining to void Hesitance
Outline assessments for diagnosis of UTI
Clinical: symptoms and signs
Urinalysis (visual + chemical + microscopic)
Microbiological: Urine culture
Methods of urine collection and indications
Bag urine - urinalysis only
Mid-stream urine (most common) - urinalysis and culture with sensitivity testing
Clean-catch urine - urinalysis and culture with sensitivity testing
Urethral catherization - unable to void, urinalysis and culture with sensitivity testing
Suprapubic aspiration (SPT) - pediatric/ patients with spinal cord injury and paraplegia, urinalysis and culture with sensitivity testing
Relative risks/ drawbacks of different methods of urine collection
Bag urine - contamination by perineal flora
Mid-stream urine - prone to contamination, not applicable in children
urethral catherization - risk of iatrogenic UTI
Suprapubic aspiration - risk of bowel perforation, bowel injury
Outline spectrum of tests in urinalysis
Chemical: pH, osmality, specific gravity …etc
Microscopic: Erythrocytes, Leukocytes, Bacteria, Epithelial cells (contamination marker)
Adjunctive: Leukocyte Esterase, Nitrites
Indications for radiological evaluation for UTI
Persistent infection
* Persistent clinical symptoms after 48 – 72 hours of antibiotic therapy
* Repeated pyelonephritis
* Urosepsis
Altered anatomy
* Renal stones/ mechanical obstructions
* History of urological surgery/ anatomical abnormalities
Weak immune system
* Diabetes mellitus
* Immunosuppression
Cause of abnormally alkaline urine pH in UTI
Normal urine pH = 5.5 - 6.5
pH >7.5 indicate urease-producing bacterial esp. in presence of stones
e.g. Proteus, Klebsiella, Pseudomonas
Bacteria observed in direct microscopy of urine equate UTI. True or False?
False
Bacteria only seen in 10^5 CFE/ mL
May be normal flora or contamination
Can be sterile bacteriuria
Urinalysis adjunctive tests
Mechanism of action
Pyuria: Leukocyte esterase
o Leukocyte esterase is released by lysed neutrophils and macrophages and is a marker for the presence of WBC
Bactiuria: Nitrite test
o Enterobacteriaceae express nitrate reductase which converts urinary nitrate into nitrite
o FN results in Gram +ve or Pseudomonas UTI
Define cut-off values for pyuria and bacteriuria
Pyuria = > 2 WBC/ high power field (OR) > 10 WBC/mL
Bacteriuria:
≥ 10^3 cfu per ml for female uncomplicated cystitis
> 10^4 cfu/ml in female uncomplicated pyelonephritis
> 10^5 cfu/ml in female or 10^4 cfu/ml in male complicated UTI
Suprapubic aspiration: any bacteria growth is +ve
Ddx for sterile pyuria
pyuria without bacteriuria
TB partially treated UTI urinary tract stones bladder cancer inflammatory conditions such as interstitial cystitis and ketamine cystitis
Causes of false negative in leukocyte esterase test in urinalysis
Causes of false negative in nitrite test
Leukocyte esterase false negative High specific gravity/ dehydration Glycosuria Urobilinogen High Vit C low WBC: WBC lysis and Neutropenia
Nitrite:
Pseudomonas/ gram-positive UTI
low specific gravity urine
Define asymptomatic bacteriuria
≥ 10^5 cfu/ml and ≥ 10^3 cfu/ml in women and men urine
without symptoms and signs
Recommended screening and treatment of asymptomatic bacteriuria is indicated which patients
Pregnant pt: UTI asso with premature birth, LBW
Planned invasive genitourinary surgery with risk of mucosal bleeding
not clinically indicated for DM patients
7 loci of UTI
Cystitis Pyelonephritis Pyonephorsis/ Renal abscess Prostatitis Epididymo-orchitis Urethritis
Acute Cystitis:
Classical presentation
Ddx
Treatment
Dysuria, frequency, urgency
Haematuria
Foul-smelling urine
No vaginal discharge or systemic upset
Ddx:
Other non-infective cystitis
Vaginosis
Herpes
Tx:
- amoxicillin-clavulanate (Augmentin)* or Fluoroquinolone (3 days)
- Nitrofurantoin (7 days)
Acute Pyelonephritis:
Classical presentation
Treatment
Fever, chills Vomiting Loin pain Sepsis Haematuria
Treatment:
USG imaging for underlying obstructions, Contrast CT for renal abscess or obstruction after 72h without improvement
14 days Fluoroquinolone or 3rd gen. cephalosporins
Aminoglycosides/ carbapenems for FQ-resistant
Indications to investigate male UTI
Empirical treatment for male UTI
Febrile UTI Pyelonephritis Recurrent UTI (prostatitis?) AROU/ history of voiding problems Persistent microscopic haematuria
7 days augmentin/ fluoroquinolone for male cystitis
2-6 weeks quinolones for prostatitis
Risk factors for elderly UTI
- Prostate enlargement **
- Urinary obstruction e.g. Fecal impaction, Pelvic organ prolapse/ Cystocele
- Poor perineal hygiene (fecal)
- Neurologic impairment- Neurogenic bladder, large post void residual volume, drug induced
- Post-menopausal changes: atrophic vaginitis
Prevention measures for UTI
Lifestyle modification
• Liberal fluid intake to increase micturition
• Avoid use of spermicide-containing products
• Post-coital voiding
Antibiotic prophylaxis with co-trimoxazole or nitrofurantoin
• Continuous, post-coital, intermittent
Manifestation of genitourinary TB
Kidneys:
- Abscess, fibrosis
- Calcified, non-functional kidney
Ureter strictures
Bladder: cystitis, contracted “thimble” bladder, Golf-hole ureteral orifice
Epididymis, Vas Deferens: abscess, sinus, infertility, discharge
Prostate: Nodules
S/S for genitourinary TB
Chronic and non-specific:
Frequency, dysuria, loin pain, haematuria, suprapubic pain, fever
Genital:
Scrotal sinus with discharge, epididymal/ prostatic nodules/ vas deferens beading
Investigations for genitourinary TB
Treatment
AFB smear
Culture: lowenstein-jensen medium
PCR
HREZ therapy
