Updated: 11/4/2019

Urinary Tract Infection

Topic
Review Topic
0
0
Questions
9
0
0
Evidence
7
0
0
https://upload.medbullets.com/topic/115070/images/08072017vldstep1renalurinarytractinfection.jpg
https://upload.medbullets.com/topic/115070/images/08032017vldstep1urinarytractinfectionpathogenesis-moisesedits.jpg
Snapshot
  • A 23-year-old woman presents to her primary care physician due to pain with urination and increased urinary frequency. She reports that her symptoms began approximately 3 days ago and has not noticed any abnormal smell, vaginal discomfort, or vaginal discharge. The patient is otherwise healthy and states that she has been having sexual intercourse more frequently with her partner. She infrequently uses condoms and is on oral contraception. Her vital signs and physical examination is unremarkable. She is started on oral nitrofurantoin for 5 days. (Acute uncomplicated cystitis)
Introduction
  • Clinical definitionurinary tract infections (UTI) can either be asymptomatic or symptomatic and encompasses
      • asymptomatic bacturia (ASB)
        • there is bacteria in the urinary tract; however, the patient has no symptoms
        • typically patients do not require treatment
          • pregnant women require screening and treatment
            • this is because ASB in pregnancy is associated with
              • pre-term birth
              • perinatal death
              • pyelonephritis in the mother
      • cystitis
      • prostatitis
      • pyelonephritis
        • neutrophillic infiltration of the interstitium and tubular lumen on histology
    • it is important to distinguish between uncomplicated versus complicated UTI
      • uncomplicated UTI
        • this describes acute cystitis or pyelonephritis in outpatient women who are not pregnant and do not have anatomic abnormalities or instrumentation within the urinary tract
      • complicated UTI
        • this describes UTI that is not uncomplicated
  • Epidemiology
    • incidence
      • 50-80% of women acquire at least 1 UTI
      • 20-30% of women with 1 UTI have recurrent infections
    • demographics
      • more common in women, elderly, and infants
    • location
      • bladder
      • prostate
      • kidneys
    • risk factors
      • female
      • benign prostatic hyperplasia
      • frequent sexual intercourse
      • history of UTI
      • incontinence
      • diabetes mellitus
      • vasicoureteral reflux
      • spermicide use
  • Pathogenesis
    • in most cases bacteria ascends from the urethra to the bladder (cystitis)
      • bacterial organisms can further ascend through the ureter and infect the kidney causing a renal parenchymal infection (pyelonephritis)
      • note that infection and symptom development depends on the
        • host
          • e.g., genetic background, behavioral factors, and underlying disease
        • pathogen
        • environmental factors
          • e.g., vaginal microflora, medical devices (e.g., indwelling catheters), and urinary retention
        • for example, voiding and the host's innate immune response eliminates bacterial colonization in the bladder after sexual intercourse
          • however, an indwelling catheter, stone, or any other foreign body provides a surface where bacteria can colonize
      • hematogenous spread to the urinary tract can also result in a UTI; however, this is rare
        • e.g., Salmonella, S. aureus, and Candida
  • Prognosis
    • ASB in elderly or catheterized patients does not increase the risk of death
    • recurrent UTI in children and adults does not result in chronic pyelonephritis or renal failure
      • this is true when there are not anatomic abnormalities
 
Microbiology of Urinary Tract Infections
Microbe
Findings
Comments
E. coli 
  • Green metallic sheen on EMB agar
  • Most common cause of UTI 
S. saprophyticus
-
  • Second most common cause in sexually active women
K. pneumoniae
  • Large mucoid capsule and viscous colonies
  • Third most common cause
S. marcescens
  • Red pigment production by select strains
-
Enterococcus -
  • Typically a nosocomial infection that is drug-resistant
P. mirabilis
  • "Swarming" appearance on agar
  • Urease positive
  • Can result in struvite stone formation 
-
P. aeruginosa
  • Blue-green pigment
  • Typically a nosocomial infection that is drug-resistant
 
Presentation
  • Symptoms/physical exam/findings
    • ASB
      • asymptomatic patient with an incidental finding of bacteruria on urine culture
    • cystitis
      • dysuria
      • urinary frequency
      • urgency
      • nocturia
      • suprapubic discomfort
      • gross hematuria
    • prostatitis
      • dysuria
      • frequency
      • pain in the prostatic pelvic or perineal area
      • bladder outlet obstruction
      • fever and chills
    • pyelonephritis
      • fever
        • this is the main feature that distinguishes pyelonephritis from cystitis
      • costovertebral angle pain
        • may be absent in mild pyelonephritis
      • obstructive uropathy in patients with diabetes
        • this is secondary to acute papillary necrosis that results in the papillae to slough and subsequently obstruct the ureter
      • emphysematous pyelonephritis in patients with diabetes
        • gas is produced in the renal and perinephric areas
Studies
  • Labs
    • urine dipstick
      • nitrite positivity suggests an E. coli infection or other infection of the Enterobacteriaceae family
      • leukocyte esterase positive
      • urease positivity suggests an S. saprophyticus, Proteus, or Klebsiella infection
    • urinalysis
      • > 10 white blood cells (WBCs)/mL
      • > 1000 CFU/mL
      • white blood cell casts
        • a diagnostic finding of an upper urinary tract infection (e.g., pyelonephritis)
    • urine culture
      • gold standard for diagnosing UTI
      • may appear sterile if caused by chlamydia 
        • most common cause of sterile pyuria in sexually active males age 20-30
  • Histology
    • chronic pyelonephritis
      • "thyroidization" of tubules due to eosinophilic casts contained in the tubules
Differential
  • Acute hemorrhagic cystitis
    • can be caused by adenovirus
  • Urethritis
  • Nephrolithiasis
  • Genitourinary malignancy
Treatment
  • Medical
    • TMP-SMX or nitrofurantoin
      • indications
        • first-line for uncomplicated UTI
          • second-line agents include a fluoroquinolone or β-lactam
        • nitrofurantoin, ampicillin, and cephalosporins can be used in the treatment of UTI in pregnant women
          • sulfonamides should not be used due to its possible teratogenic effects (in first trimester) and kernicterus development (near term)
          • fluoroquinolones should also be avoided in pregnancy due to its negative effect on the development of fetal cartilage
        • TMP-SMX or a fluoroquinolone is used in the treatment of prostatitis
    • fluoroquinolones (e.g., ciprofloxacin)
      • indication
        • first-line for acute uncomplicated pyelonephritis
    • fluconazole
      • indication
        • first-line treatment for Candida-related UTI
  • Operative
    • nephrectomy
      • indications
        • treatment for xanthogranulomatous pyelonephritis
    • percutaneous drainage
      • indications
        • treatment for emphysematous pyelonephritis and it may be followed by elective nephrectomy
Complications
  • Uncomplicated UTI
    • complications are uncommon
  • Complicated UTI
    • bacteremia
    • urosepsis
    • systemic inflammatory response syndrome (SIRS)
    • renal and perinephric abscess
    • emphysematous pyelonephritis
    • xanthogranulomatous pyelonephritis
      • associated with long-term urinary tract obstruction and infection
        • this results in chronic destruction of the renal parenchyma via a granulomatous process
    • malakoplakia
    • renal papillary necrosis
  • UTI in pregnancy
    • pyelonephritis
    • sepsis
    • chorioamnionitis
    • preterm labor
    • low birth weight
    • hypertension and pre-eclampsia
  • UTI in men
    • acute or chronic prostatitis
    • urethritis
    • acute epididymitis
    • orchitis
 

 

Please rate topic.

Average 4.1 of 7 Ratings

Thank you for rating! Please vote below and help us build the most advanced adaptive learning platform in medicine

The complexity of this topic is appropriate for?
How important is this topic for board examinations?
How important is this topic for clinical practice?
Questions (9)
Lab Values
Blood, Plasma, Serum Reference Range
ALT 8-20 U/L
Amylase, serum 25-125 U/L
AST 8-20 U/L
Bilirubin, serum (adult) Total // Direct 0.1-1.0 mg/dL // 0.0-0.3 mg/dL
Calcium, serum (Ca2+) 8.4-10.2 mg/dL
Cholesterol, serum Rec: < 200 mg/dL
Cortisol, serum 0800 h: 5-23 μg/dL //1600 h:
3-15 μg/dL
2000 h: ≤ 50% of 0800 h
Creatine kinase, serum Male: 25-90 U/L
Female: 10-70 U/L
Creatinine, serum 0.6-1.2 mg/dL
Electrolytes, serum  
Sodium (Na+) 136-145 mEq/L
Chloride (Cl-) 95-105 mEq/L
Potassium (K+) 3.5-5.0 mEq/L
Bicarbonate (HCO3-) 22-28 mEq/L
Magnesium (Mg2+) 1.5-2.0 mEq/L
Estriol, total, serum (in pregnancy)  
24-28 wks // 32-36 wks 30-170 ng/mL // 60-280 ng/mL
28-32 wk // 36-40 wks 40-220 ng/mL // 80-350 ng/mL
Ferritin, serum Male: 15-200 ng/mL
Female: 12-150 ng/mL
Follicle-stimulating hormone, serum/plasma Male: 4-25 mIU/mL
Female: premenopause: 4-30 mIU/mL
midcycle peak: 10-90 mIU/mL
postmenopause: 40-250
pH 7.35-7.45
PCO2 33-45 mmHg
PO2 75-105 mmHg
Glucose, serum Fasting: 70-110 mg/dL
2-h postprandial:<120 mg/dL
Growth hormone - arginine stimulation Fasting: <5 ng/mL
Provocative stimuli: > 7ng/mL
Immunoglobulins, serum  
IgA 76-390 mg/dL
IgE 0-380 IU/mL
IgG 650-1500 mg/dL
IgM 40-345 mg/dL
Iron 50-170 μg/dL
Lactate dehydrogenase, serum 45-90 U/L
Luteinizing hormone, serum/plasma Male: 6-23 mIU/mL
Female: follicular phase: 5-30 mIU/mL
midcycle: 75-150 mIU/mL
postmenopause 30-200 mIU/mL
Osmolality, serum 275-295 mOsmol/kd H2O
Parathyroid hormone, serume, N-terminal 230-630 pg/mL
Phosphatase (alkaline), serum (p-NPP at 30° C) 20-70 U/L
Phosphorus (inorganic), serum 3.0-4.5 mg/dL
Prolactin, serum (hPRL) < 20 ng/mL
Proteins, serum  
Total (recumbent) 6.0-7.8 g/dL
Albumin 3.5-5.5 g/dL
Globulin 2.3-3.5 g/dL
Thyroid-stimulating hormone, serum or plasma .5-5.0 μU/mL
Thyroidal iodine (123I) uptake 8%-30% of administered dose/24h
Thyroxine (T4), serum 5-12 μg/dL
Triglycerides, serum 35-160 mg/dL
Triiodothyronine (T3), serum (RIA) 115-190 ng/dL
Triiodothyronine (T3) resin uptake 25%-35%
Urea nitrogen, serum 7-18 mg/dL
Uric acid, serum 3.0-8.2 mg/dL
Hematologic Reference Range
Bleeding time 2-7 minutes
Erythrocyte count Male: 4.3-5.9 million/mm3
Female: 3.5-5.5 million mm3
Erythrocyte sedimentation rate (Westergren) Male: 0-15 mm/h
Female: 0-20 mm/h
Hematocrit Male: 41%-53%
Female: 36%-46%
Hemoglobin A1c ≤ 6 %
Hemoglobin, blood Male: 13.5-17.5 g/dL
Female: 12.0-16.0 g/dL
Hemoglobin, plasma 1-4 mg/dL
Leukocyte count and differential  
Leukocyte count 4,500-11,000/mm3
Segmented neutrophils 54%-62%
Bands 3%-5%
Eosinophils 1%-3%
Basophils 0%-0.75%
Lymphocytes 25%-33%
Monocytes 3%-7%
Mean corpuscular hemoglobin 25.4-34.6 pg/cell
Mean corpuscular hemoglobin concentration 31%-36% Hb/cell
Mean corpuscular volume 80-100 μm3
Partial thromboplastin time (activated) 25-40 seconds
Platelet count 150,000-400,000/mm3
Prothrombin time 11-15 seconds
Reticulocyte count 0.5%-1.5% of red cells
Thrombin time < 2 seconds deviation from control
Volume  
Plasma Male: 25-43 mL/kg
Female: 28-45 mL/kg
Red cell Male: 20-36 mL/kg
Female: 19-31 mL/kg
Cerebrospinal Fluid Reference Range
Cell count 0-5/mm3
Chloride 118-132 mEq/L
Gamma globulin 3%-12% total proteins
Glucose 40-70 mg/dL
Pressure 70-180 mm H2O
Proteins, total < 40 mg/dL
Sweat Reference Range
Chloride 0-35 mmol/L
Urine  
Calcium 100-300 mg/24 h
Chloride Varies with intake
Creatinine clearance Male: 97-137 mL/min
Female: 88-128 mL/min
Estriol, total (in pregnancy)  
30 wks 6-18 mg/24 h
35 wks 9-28 mg/24 h
40 wks 13-42 mg/24 h
17-Hydroxycorticosteroids Male: 3.0-10.0 mg/24 h
Female: 2.0-8.0 mg/24 h
17-Ketosteroids, total Male: 8-20 mg/24 h
Female: 6-15 mg/24 h
Osmolality 50-1400 mOsmol/kg H2O
Oxalate 8-40 μg/mL
Potassium Varies with diet
Proteins, total < 150 mg/24 h
Sodium Varies with diet
Uric acid Varies with diet
Body Mass Index (BMI) Adult: 19-25 kg/m2
Calculator

Question locked
Sorry, this question is for
PEAK Premium Subscribers only
Upgrade to PEAK
Question locked
Sorry, this question is for
PEAK Premium Subscribers only
Upgrade to PEAK
Question locked
Sorry, this question is for
PEAK Premium Subscribers only
Upgrade to PEAK

You have 100% on this question.
Just skip this one for now.

(M1.RL.4756) A 4-year-old male is accompanied by his mother to the pediatrician. His mother reports that over the past two weeks, the child has had intermittent low grade fevers and has been more lethargic than usual. The child’s past medical history is notable for myelomeningocele complicated by lower extremity weakness as well as bowel and bladder dysfunction. He has been hospitalized multiple times at an outside facility for recurrent urinary tract infections. The child is in the 15th percentile for both height and weight. His temperature is 100.7°F (38.2°C), blood pressure is 115/70 mmHg, pulse is 115/min, and respirations are 20/min. Physical examination is notable for costovertebral angle tenderness that is worse on the right. Which of the following would most likely be found on biopsy of this patient’s kidney? Review Topic

QID: 108920
1

Mononuclear and eosinophilic infiltrate

18%

(41/233)

2

Replacement of renal parenchyma with foamy histiocytes

18%

(42/233)

3

Destruction of the proximal tubule and medullary thick ascending limb

15%

(34/233)

4

Diffusely necrotic papillae with dystrophic calcification

17%

(40/233)

5

Tubular colloid casts with diffuse lymphoplasmacytic infiltrate

27%

(62/233)

M1

Select Answer to see Preferred Response

SUBMIT RESPONSE 5
Question locked
Sorry, this question is for
PEAK Premium Subscribers only
Upgrade to PEAK

You have 100% on this question.
Just skip this one for now.

(M1.RL.4671) A 22-year-old sexually active, otherwise healthy female presents to her primary care physician complaining of several days of dysuria, frequency, urgency, and suprapubic pain. She denies fever, flank pain, vaginal itching, or vaginal bleeding/discharge. Which organism is most likely responsible for this patient's symptoms? Review Topic

QID: 107151
1

Staphylococcus saprophyticus

37%

(14/38)

2

Chlamydia trachomatis

5%

(2/38)

3

Proteus mirabilis

0%

(0/38)

4

Klebsiella pneumoniae

0%

(0/38)

5

Escherichia coli

58%

(22/38)

M1

Select Answer to see Preferred Response

SUBMIT RESPONSE 5
Question locked
Sorry, this question is for
PEAK Premium Subscribers only
Upgrade to PEAK

You have 100% on this question.
Just skip this one for now.

(M1.RL.4671) A 34-year-old female presents to her primary care physician with complaints of fevers, nausea/vomiting, and severe left flank pain that has developed over the past several hours. She denies any prior episodes similar to her current presentation. Physical examination is significant for a body temperature of 39.1 C and costovertebral angle tenderness. A urinalysis and urine microscopy are ordered. Which of the following findings on kidney histology would be expected in this patient? Review Topic

QID: 107161
1

Interstitial fibrosis and lymphocytic infiltrate

13%

(14/111)

2

Neutrophils filling the lumens of the renal tubules

68%

(76/111)

3

Thickening of the capillaries and glomerular basement membrane

5%

(5/111)

4

Scarring of the glomeruli

5%

(6/111)

5

Enlarged, hypercellular glomeruli with 'wire-looping' of capillaries

5%

(6/111)

M1

Select Answer to see Preferred Response

SUBMIT RESPONSE 2

You have 100% on this question.
Just skip this one for now.

(M1.RL.49) A 33-year-old female presents with recent onset of painful urination, fever, and right flank pain. Urinary sediment analysis is positive for the presence of white blood cell casts and Gram-negative bacteria. She has not recently started any new medications. What is the most likely diagnosis in this patient? Review Topic

QID: 101267
1

Pelvic Inflammatory Disease

3%

(1/30)

2

Acute Interstitial Nephritis

3%

(1/30)

3

Pyelonephritis

90%

(27/30)

4

Cystitis

3%

(1/30)

5

Appendicitis

0%

(0/30)

M1

Select Answer to see Preferred Response

SUBMIT RESPONSE 3
ARTICLES (7)
Topic COMMENTS (11)
Private Note