Urinary tract infection

Resident Survival Guide

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Urinary Tract Infection Microchapters
Patient Information
Overview
Classification Pyelonephritis Cystitis Prostatitis Urethritis Asymptomatic bacteriuria
Causes
Differential Diagnosis
Treatment

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Usama Talib, BSc, MD [2]

Synonyms and keywords: UTI

Overview

A urinary tract infection is an infection that involves any part of the urinary tract. It can result due to the invasion by a bacteria, virus, fungus or any other pathogen. The most common cause of a urinary tract infection is a bacterial infection. Depending on the site of the infection a UTI can be classified as either upper or lower UTI. Lower UTI includes urethritis, prostatitis, asymptomatic bacteriuria and cystitis (bladder infection) where as Upper UTI may include Pyelonephritis (infection of the kidney) and rarely uretritis (infection of the ureters). Each subtype of urinary tract infection can also be sub classified on the basis of duration, etiology or therapeutic approach as acute, chronic or recurrent and as uncomplicated or complicated infections.

The urine is normally sterile, a urinary tract infection occurs when the normally sterile urinary tract is infected by bacteria, which leads to irritation and inflammation. Pyelonephritis and Cystitis result mostly from ascending infections from the urethra (Urethritis) but can also result from descending infections i.e hematogenous spread, or by the lymphatic system. The condition more often affects women, but can affect either gender and all age groups. The pathogenesis of a complicated UTI may include obstruction and stasis of urine flow. Various factors are associated with the risk of developing a urinary tract infection. A common cause of the urinary tract infection in hospital settings is the urinary catheter placement. Diabetes, Crohn's disease, iatrogenic causes, endometriosis, pelvic inflammatory disease, urinary obstruction, and bladder incontinence are some risk factors for acquiring a UTI. A thorough physical exam is very helpful in differentiating Upper from Lower UTI]s. Patients with an uncomplicated UTI are usually well-appearing. The symptoms may include abnormal urine color (cloudy), blood in the urine, frequent urination or urgent need to urinate, dysuria, pressure in the lower pelvis or back, suprapubic pain, flank pain, back pain, fever, nausea, vomiting, and chills. Urinalysis and urine culture are very helpful laboratory tests in diagnosing a urinary tract infection. Pyuria and either white blood cells (WBCs) or red blood cells (RBCs) may be seen on urinalysis. Escherichia coli ("E. coli"), a bacterium found in the lower gastrointestinal tract is one of the most common culprits. The individual infection must be differentiated from various causes of dysuria such as cystitis, acute pyelonephritis, urethritis, prostatitis, vulvovaginitis, urethral strictures or diverticula, benign prostatic hyperplasia and neoplasms such as renal cell carcinoma and cancers of the bladder, prostate, and penis. Antimicrobial therapy is indicated in case of a symptomatic UTI.A large proportion of patients with acute uncomplicated urinary infections will recover without treatment within a few days or weeks. If left untreated, some patients may progress to develop recurrent infection, involve and infect other parts of the urinary tract, hematuria, and rarely renal failure. Prognosis is generally good for lower UTIs. The treatment of a UTI depends on the type of the disease, the disease course (acute uncomplicated vs. complicated), history of the individual and the rates of resistance in the community. Preventative measures to avoid a UTI include abstinence from sexual activity, use of barrier contraception during sexual intercourse, urinating after intercourse, increasing fluid intake and frequency of urination, and use of estrogen (among post-menopausal women).

Classification

Urinary Tract Infections

Upper UTI

Lower UTI

Pyelonephritis

Cystitis

Prostatitis

Urethritis

Asymptomatic bacteriuria

❑Acute Uncomplicated ❑Acute Complicated ❑Chronic ❑ Emphysematous ❑ Xanthogranulomatous

❑ Acute Uncomplicated ❑ Complicated ❑ Recurrent/Chronic

❑ Acute Bacterial ❑ Chronic bacterial ❑ Chronic Inflammatory ❑ Chronic non-inflammatory ❑ Asymptomatic

Causes

Common Pathogens	Pyelonephritis	Cystitis	Urethritis	Prostatitis	Asymptomatic Bacteriuria
Ecoli*	✔(70%)	✔(78.6%)	-	✔(58%)	✔(80%)
Klebsiella	✔	✔(4.3%)	-	✔	✔
Proteus	✔	✔(3.7%)	-	✔	✔
Neisseria gonorrhoeae	-	-	✔(21.6%)	✔	-
Pseudomonas	✔	✔	-	✔	✔
Staphylococcus	✔	✔	-	✔	✔
Chlamydia trachomatis	✔	✔	✔(20-30%)	✔	-
Mycoplasma	✔	-	✔	-	-
Trichomonas	✔	✔	✔	✔	-

*Ecoli is the most common cause of all urinary tract infections

• For more causes of Pyelonephritis click here.
• For more causes of Cystitis click here.
• For more causes of Urethritis click here.
• For more causes of Prostatitis click here.
• For more causes of Asymptomatic bacteriuria click here.

Differential Diagnosis

Diseases	Diagnostic tests			Physical Examination				Symptoms					Past medical history	Other Findings
	Urinalysis	Urine Culture	Gold Standard	Fever	Tenderness	Discharge	Inguinal Lymphadenopathy	Hematuria	Pyuria	Frequency	Urgency	Dysuria
Differentiating amongst different types of Urinary Tract Infections:
Pyelonephritis	Leukocytes Nitrite +ve	Identifies causative bacteria	Imaging and culture	✔	Flank or costovertebral angle	✔	✔	✔	✔	-	-	✔	History of Pyelonephritis Recent history of Hospitalisation Nephrolithiasis Immunosupression	Costovertebral angle tenderness Patient is in acute distress Look for obstructive causes
Cystitis	Nitrite +ve Leukocyte estrase+ve WBCs RBCs	>100,000CFU/mL	Urinary culture	✔	Suprapubic	-	✔	✔	✔	✔	✔	✔	Recent catheterisation Pregnancy recent intercourse Diabetes Personal or Family History of UTI Known abnormality of the urinary tract BPH or HIV	Imaging studies help differentiate the type May company back pain, nausea, vomiting and chills
Urethritis	Positive leukocyte esterase test or >10 WBCs Mucous threads in the morning urine	-	Gram stain & Mucoid or purulent discharge	✔	-	Urethral discharge	✔	-	✔	-	-	✔	Prior STDs Urinary tract infections New sexual partner Recent intercourse Recent catheterisation	Purulent discharge may suggest gonorrhoea Exclusive dysuria suggest Chlamydia Painful genital ulcers with dysuria suggest HSV
Prostatitis	10-20 leukocytes for acute and chronic bacterial subtypes	Identifies causative bacteria (in bacterial subtypes)	Urine Culture	✔	-	-	-	-	✔	✔	✔	✔	Urogenital disorders Recent catheterization or other genitourinary instrumentation History of UTIs	In acute prostatitis, palpation reveals a tender and enlarged prostate[1][3] In chronic prostatitis, palpation reveals a tender and soft (boggy) prostate[1] A prostate massage should never be done in a patient with suspected acute prostatitis, since it may induce sepsis
Bacterial Vulvovagintis	-	-	Gram Stain & Culture of discharge	✔	-	Vaginal discharge	✔	-	-	-	-	✔	Number and type of sexual partners (new, casual, or regular) Prior STDs Previous history of symptomatic BV in female partner (in homosexual women)	Fishy odor from the vagina (Whiff test) Thin, white/gray homogeneous vaginal discharge Microscopy (wet prep) and vaginal pH  Clue cells
Cervicitis	-	-	culture for gonococcal cervicitis	✔	Cervical	endocervical exudate	-	-	✔	-	-	✔	Abnormal vaginal bleeding after intercourse or after menopause Abnormal vaginal discharge Painful sexual intercourse Pressure or heaviness in the pelvis	Purulent or mucopurulent endocervical exudate Sustained endocervical bleeding easily induced by a cotton swab >10 WBC in vaginal fluid, in the absence of trichomoniasis, may indicate endocervical inflammation caused specifically by C. trachomatis or N. gonorrhea
Epididymitis	Hematuria may be seen	✔	Culture	✔	Testicular & Suprapubic	+/- urethral discharge	✔	✔	-	✔	✔	✔	Scrotal pain: starts gradually, is usually unilateral and localized posterior to the testis Scrotal swelling Scrotal wall erythema Constitutional symptoms: feeling of hotness, chills, nausea and vomiting	Ultrasound in patients with acute testicular pain to assess for testicular torsion If equivocal do surgical exploration
Syphilis (STD)	-	-	Darkfield Microscopy	+/-	-	-	✔	-	-	-	-	-	History of STD HIV Immunosupression Previous history of chancre	May be asymptomatic Painless chancre in primary syphilis Secondary syphilis may have generalised features and condylomata late Tertiary syphilis can have neurosyphilis, cardiovascular syphilis and gummas
BPH	Hematuria may be seen	-	DRE & Serum PSA	-	-	-	-	✔	-	✔	✔	✔	Sudden inability to urinate Urinary tract infections Urinary stones Damage to the kidneys Blood in the urine	Involves mainly central or transitional zone Hyperplasia rather than hypertrophy Obstruction of the urethra Nocturia
Neoplasms	Hematuria may be seen	-	Imaging and biopsy	+-	-	-	✔	✔	-	✔	✔	-	Sudden inability to urinate Recurrent urinary tract infections Weight loss and other constitutional symptoms	Cachexia Gradual progression

Management

UTI confirmed with urine culture (≥ 105 CFU/mL) + Pyuria

Is there suprapubic pain?

Yes

No

Consider Cystitis

Is there flank or back pain?

Acute uncomplicated cystitis Preferred regimen TMP-SMX 160/800mg bid x 3 days OR Nitrofurantoin monohydrate/macrocrystals 100mg bid x 5-7 days OR Fosfomycin trometamol 3g once (single dose) OR Pivmecillinam 400mg bid x 5 days Alternative regimen: Template:See main

Complicated/Catheter-Associated Cystitis Preferred regimen For those who can tolerate ORALLY Ciprofloxacin 500mg PO bid x 5-14 days OR Ciprofloxacin Extended Release 1000mg daily x 5-14 days OR PARENTERALLY IV Levofloxacin 500mg OR IV Ceftriaxone 1g OR IV Ertapenem 1g Catheter-Associated UTI Remove catheter or intermittent catheterization Use same antibiotic therapy as above for CA-Cystitis Alternative regimen: Template:See main

Acute Cystitis in Pregnancy Preferred regimen Nitrofurantoin 100mg PO q12h x 5 days OR Amoxicillin-clavulanate 500mg PO q12h 3-7 days OR Fosfomycin 3g PO single dose Alternative regimen: TMP-SMX DS PO bid x 3 days only in 2nd trimester Template:See main

Yes

No

Consider pyelonephritis

Consider alternative diagnosis such as; Prostatitis Urethritis Renal abscess

Acute uncomplicated pyelonephritis (Outpatient) Preferred regimen Ciprofloxacin (immediate release) 500mg bid x 7 days Ciprofloxacin (extended release) 1000mg once daily x 7 days OR Levofloxacin 750mg once daily x 5 days OR TMP-SMX 160/800mg bid x 14 days Alternative regimen: Template:See main

Complicated pyelonephritis (Inpatient) Preferred regimen IV Ceftriaxone 1g q24h OR IV Ciprofloxacin 400mg q12h OR IV Levofloxacin 750mg q24h OR IV Cefepime q12h Alternative regimen: Template:See main

Acute pyelonephritis in Pregnancy Preferred regimen IV Ceftriaxone 1g q24h OR IV Ampicillin 1-2g q6h OR IV Cefepime 1g q12h Alternative regimen: Template:See main

Is there urethral discharge?

Yes

No

Consider Urethritis For treatment of urethritis: Template:See main

Weak urine stream or hesitancy?

Yes

No

Consider Prostatitis

Renal USS to rule out renal abscess (drainage + antibiotics for renal abscess) Other investigations (Abdominal CT, VSUG, for anatomic abnormality or obstructions