UTI Flashcards
Urine
Made by the kidneys by filtering wastes and extra water from the blood
1-2 L of urine is produced daily
Polyuria: excessive urine output; > 2L/day
Oliguria: output of < 500 mL/day
Anuria: output of < 100 mL/day
Bodily fluid used for medical evaluation
Appearance
Yellow color due to urochrome, a pigment from the breakdown of hemoglobin
Variation of color due disease states, hydration status, foods eaten, and medications
Pyuria: pus in the urine; cloudy due to infection
Hematuria: blood in the urine; can be gross or microscopic
Urine
Odor, composition, pH, specific gravity
Odor
Affected by the foods we eat
“fruity” odor: acetone in diabetic patients
“foul/strong” odor: may indicate acute UTI
Chemical composition
95% water and 5% solutes (urea, sodium, potassium, chloride)
Glucose, free hemoglobin, albumin, ketones, and bile pigments in urine are indicators of disease
pH
Ranges from 4.5-8.2, but is normally mildly acidic at 6.0
Specific gravity
Ratio of the density of a substance to the density of distilled water
Range from 1.001 (dilute) to 1.035 (concentrated)
UTI
general
Pathogenic process that develops when a microorganism (usually bacteria) enters the body through the urethra
Infections of the lower urinary tract:
Urethritis
Prostatitis
Cystitis (infection of the bladder)
Infections of the upper urinary tract:
Pyelonephritis (infection of the kidney)
Differentiating between the sites of infection can be difficult
Infection can and often spreads from one site to another
UTI
Factors/Mechanism to Maintain Sterility
Host defense mechanisms exist to maintain sterility and prevent infection
Urine acidity
High urea concentration
Emptying of the bladder (micturition)
Ureterovesical and urethral sphincters
Mucous secretions
Urethra in ♀
Prostate in ♂
Protective uroepithelial immune response
Secretion of uromodulin from the kidneys
UTI
RF
Women > men
Shorturethra predisposes all women
Less distance forbacteria to ascend to thebladder
Less time for micturition to wash away ascendingbacteriain theurethra
Comorbidities
Immunocompromised state
Diabetes (glucosuriaprovides a food source forbacteria)
History of UTIs
Behavioral
Poor hygiene andfecal incontinence(↑ genital and periurethralcolonization)
Sexual intercourse:
Facilitates bacterialinfections in women
Anal-insertive intercourse may result in bacterial infections in men
Use of spermicides:
Alterations of the vaginal flora to allow overgrowth of bacteria (E. coli)
Anatomical (causes of urinary stasis/obstruction):
Posterior urethral valves → ureteral reflux →pyelonephritis
Benign prostatichyperplasia(BPH)
Urethral stricture
Cystocele
Neurogenic bladder
Nephrolithiasis
Foreign body (nidus for infection and/or allows entry into body):
Foley catheter
Suprapubic catheter
Ureteral stent
Urologic instrumentation (cystoscopy)
Medications:
Anticholinergics (diphenhydramine):
Can cause incomplete emptying of thebladder
Elderly primarily affected
Antibiotics (frequent use = ↑resistance)
UTI
Patho
Initial invasion of the urethra
Contamination of the periurethral area → colonizationof theurethra (urethritis)+ migration to the bladder
Once in thebladder
Colonization→ invasion +inflammationof the bladder(cystitis)
As the results of inflammation there is an accumulation offibrinogen
Neutrophil infiltration and immune response
Bacteria start multiplying →neutrophilsinfiltrate theurinary bladder→ systemic immune reaction
Leukocytosisand systemic symptoms and signs of infection
Abiofilmis formed and the uroepithelial surface of theureters is extensively damaged by bacterial toxins andproteases
Bacterial organisms ascend to thekidneys→pyelonephritis
UTI
Bacterial pathogen
Acute or chronic infection
Acute: single pathogen
Chronic: two or more pathogens
Enteric bacteria
Gram-negative
Escherichia coli (75-95%), Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa
Gram-positive
Staphylococcus saprophyticus, Enterococcus faecalis, and group B streptococcus
Uncomplicated UTI
Occurs without underlying abnormality or impairment of urine flow
Infection is contained to the lower urinary tract (cystitis)
Painful urination (dysuria)
Sensation of needing to urinate immediately (urgency)
Increased frequency of urination (frequency)
Suprapubicabdominal pain or pelvic pain
No associated systemic symptoms
No suspicious symptoms of:
Pyelonephritis (flankpain, costovertebral angle tenderness)
STIs (urethritis,pelvic inflammatory disease (PID), urethral/vaginal discharge,dyspareunia)
Prostatitis (perinealpain, prostaticpain, urethral discharge)
Symptoms may be more vague in the elderly
Complicated UTI
Underlying factors that predispose to ascending bacterial infections
Urinary instrumentation: catheterization, cystoscopy
Anatomic abnormalities: short intravesical ureter (VUR)
Obstruction of urine flow: renal calculi, tumors, prostatic enlargement
Poor bladder emptying: neurogenic dysfunction, uterine prolapse, pregnancy
Infection that has extended beyond the bladder (pyelonephritis) or involves the bladder and is associated with fever
Acute pyelonephritis
General and Sx
Bacterial infection of the kidney parenchyma
♀>♂
Common in young girls and pregnant women after instrumentation or catheterization
~20% of acquired bacteremia cases in ♀ are from pyelonephritis
Clinical presentation
Fever and/or chills
Flank pain
Nausea and/or vomiting
Costovertebral angle (CVA) tenderness with percussion
Symptoms of cystitis may also be presents
Acute pyelonephritis
PE
In all patients assess for:
Abdominal/Suprapubic tenderness
CVA tenderness
Test is performed by using one’s fist to lightly percuss on the patient’s back (over the area where the kidneys reside)
Presence of CVA tenderness can be suggestive of an issue with the kidney (pyelonephritis)
Pelvic examination
Sexually active young women
Digital rectal examination
Men with symptoms of pelvic or perineal pain
Urethritis
General and clin man
Infection of the urethra with bacteria (or with protozoa, viruses, or fungi)
Causes
Enteric bacteria (Escherichia coli)
Sexually transmitted pathogens are common causes in ♂ and ♀
Chlamydia trachomatis
Neisseria gonorrhoeae
Trichomonas vaginalis
Injury due to instrumentation
Exposure to irritating chemical (spermicide, contraceptive jellies)
Clinical presentation:
Dysuria
Urethral discharge (male)
Urinary frequency and/or urgency
Inguinal lymphadenopathy
Prostatitis
general and clin man
Bacterial or nonbacterial swelling and inflammation of the prostate gland
Acute bacterial prostatitis
Considered a subtype of UTI
Caused by typical urinary pathogens
Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Enterococcus faecalis
Likely route of infection is ascent up the urethra and reflux of infected urine into the prostatic ducts
Clinical presentation:
Urinary frequency and/or urgency
Sensation of incomplete bladder emptying
Nocturia
Perineal or suprapubic pain
Fever
Painful ejaculation
Acute infection can progress to prostatic abscess
Prostatitis
labs and imaging
Urinalysis
Do not express prostate secretions → spread of infection (septicemia)
Pelvic CT scan or transrectal ultrasound to evaluate for abscess formation
Prostatitis
Tx
IV or oral antibiotics depending on severity
Ampicillin plus gentamicin (until afebrile)
Trimethoprim-sulfamethoxazole (Bactrim) one double-strength (160 mg/800 mg) tablet PO twice daily for 4-6 weeks
Ciprofloxacin 250-500 mg one tablet PO twice daily x 4-6 weeks
Asymptomatic Bacteriuria
Diagnosis of UTI
Requires demonstration by culture of bacteriuria
Urinalysis (UA) with reflex to urine microscopic and culture
Collection
Clean catch midstream specimen
Cleansing of genitals andurethra prior to collection
Midstreamurinecollection (discard initial volume ofurine)
Option in infants and toddlers in diapers: straight catheterization of theurethra; U-bag is often used
Catheterization: preferred in older ♀ or women with vaginal bleeding or discharge
Specimens from indwelling catheters are unreliable and should not be used for Dx of UTIs
UTI
Pyuria, Leukocyte Esterase, Nitrite
Pyuria is a marker forbacteriuria
Microscopy: ≥ 10leukocytes/µL → clinically significant pyuria
Detectable before results ofGram stain and culture:
Very sensitive for UTIs
Consider alternative diagnoses if pyuria is absent
Pyuria + characteristic symptoms of UTI → may proceed with empiric treatment
Leukocyte esterase
Enzyme released from WBCs
Nitrite
Reflects the presence ofEnterobacteriaceae (Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis) which have the bacterial enzyme that converts dietarynitratesto nitrites
Microscopic hematuria in ~50% of patients due to local tissueinflammation
UTI
Urine culture, gram stain
Indications
Urine culture
Quantitative bacterial count: ≥ 100,000colony forming units (CFUs)/mL reflectbladder bacteriuria
Multiple organisms growing simultaneously is suggestive of contamination
When to obtain?
Symptoms are suggestive, but UA is nondiagnostic
Patient that is diabetic, immunosuppressed, had recent hospitalization, urethral instrumentation, pregnant
Patients > 65 years
Symptoms of pyelonephritis
Recurrent UTI
Gram staining
Available prior to culture results and can guide therapy
Helps to narrow down the list of potential causative agents and guide empiric antibiotic selection
UTI
Testing for Additional Concerns
Concern for pregnancy
Urine or serum pregnancy testing
Concern for STD
Nucleic acid amplification testing (NAAT)
Concern for sepsis
Urinalysis
Urine culture
CBC with differential
BMP
Blood cultures x 2
Abdominal pain/tenderness: imaging (Renal US or CT scan of the abdomen and pelvis)
Complications of UTI
More likely in
Perinephric abscess, corticomedullary abscess, bacteremia, shock acute renal failure, and/or multiple organ system dysfunction
More likely in patients with:
Urinary tract obstruction
Recent urinary tract instrumentation
Urinary tract abnormalities
Elderly patients
Patients with diabetes mellitus
UTI
Outpatient VS inpatient
Increasing rates of resistance in uropathogens has been reported
Fluoroquinolones and trimethoprim-sulfamethoxazole (Bactrim)
Resistance in a treatment region reaches > 20% → antibiotic should no longer be recommended
All UTIs receive antibiotics
Outpatient management
Acute uncomplicated UTI
Acute mild complicated UTI
Inpatient management
Severely ill
Moderate to severe complicated UTI
Urinary tract obstruction is present
Patients that are unable to hydrate orally
Concern for patient adherence
UTI
Empiric Antibiotic Therapy
Considerations
Selection depends on the severity of illness, risk factors for resistant pathogens, and specific host factors (allergy/tolerability)
Urine C&S
Follow to ensure the chosen antibiotic is appropriate
Transition to an oral antibiotic with a narrow spectrum of activity to complete the antibiotic course
Severe illness or presence of urinary tract obstruction (complicated infection)
Broad-spectrum antibiotics
Consider coverage for:
Pseudomonas aeruginosa – imipenem or meropenem
methicillin-resistant Staphylococcus aureus (MRSA) – vancomycin, daptomycin, linezolid
UTI- Empiric Antibiotic Therapy
Hospitalized patient with no risk for infection with a multidrug-resistant organism
Narrow-spectrum antibiotics
Ceftriaxone (Rocephin)
Piperacillin-tazobactam (Zosyn)
Empiric Antibiotic Therapy
Outpatient
Uncomplicated UTI / Mild complicated UTI
Oral antibiotics
Uncomplicated UTI
Trimethoprim-sulfamethoxazole (Bactrim) one double-strength (160 mg/800 mg) tablet PO twice daily for 3-7 days
Nitrofurantoin (Macrobid) 100 mg PO twice daily x 5-7 days
Cephalexin (Keflex) 250-500 mg PO every 6 hours x 5-7 days
Fosfomycin (Monurol) 3 g PO once
Mild complicated UTI
Fluoroquinolones
Broad spectrum coverage against most uropathogens, including P. aeruginosa
Ciprofloxacin 500 mg PO twice daily x 7 days
Levofloxacin 750 mg PO daily x 5-7 days
Adverse effects: C. difficile infection, tendon rupture
UTI
Newest Option for Empiric Tx
Pivmecillinam
Beta-lactam antibiotic
Group of bactericidal drugs that stop bacterial cell walls from forming by binding to penicillin-binding proteins (PBPs)
Approved on April 24, 2024 by the US Food and Drug Administration (FDA) as a new treatment to treat women aged 18 years or older for uncomplicatedurinary tract infections(UTIs)
Intended to treat UTIs caused by susceptible isolates ofEscherichia coli, Proteus mirabilis,andStaphylococcus saprophyticus
Dosing: 185 mg PO 3 times daily for 3-7 days
UTI
Follow up
Symptoms should improve within 24 hours if antimicrobial therapy is effective
Repeat evaluation (face-to-face or by telephone) within 48-72 hours for acute complicated infections
Additional evaluation to include abdominal/pelvic imaging and repeat urine C&S
Worsening symptoms following the initiation of antibiotics
Persistent symptoms after 48-72 hours
Recurrent symptoms within a few weeks of treatment
Ifhematuria(nonspecific for UTIs) was found on initialurinalysis
Repeaturinalysis after completion of treatment
Do not miss a coincidental occultbladder cancer
