Urinary Tract Infections Quiz

Urinary Tract Infections (UTIs)

• UTIs are a common bacterial infection affecting the urinary tract, divided into upper and lower UTIs.
• Lower UTIs affect the bladder, urethra, and prostate, while upper UTIs affect the kidneys and pelvis.
• 40-50% of hospital-acquired infections and 10-20% of community-acquired infections are UTIs.
• UTIs are more common in newborns (boys), middle-aged women (10x more than men), and those older than 60 (men).

UTI Defense Mechanisms

• Urine flushing washes bacteria from epithelial surfaces.
• Normal flora bacteria provide protection.
• Mucus epithelium provides protection.
• Tamm-Horsfall protein helps prevent infection.

UTI Predisposing Factors (Upper)

• Structural abnormalities in the urinary tract.
• Urinary reflux (urine flowing back into the kidneys).
• Presence of kidney stones (renal calculi).

UTI Predisposing Factors (Lower)

• Bladder obstruction or tumor.
• Pregnancy.
• Catheterization.
• Autoinfection.
• Anatomical abnormalities.
• Neurological defects.
• Sexual activity.
• Age.

UTI Routes of Infection

• Ascending infection (most common): bacteria enter the urethra and ascend to the bladder and kidneys.
• Hematogenous spread: bacteria enter the bloodstream and travel to the urinary tract. (e.g., Staphylococcus aureus)
• Lymphatic spread: bacteria travel through lymph vessels to the urinary tract.
• Tissue contiguous: infection spreads from adjacent tissues.
• Fistula: abnormal connection between the urinary tract and another organ (e.g., intestine, vagina).

UTI Symptoms (Newborns)

• Non-specific symptoms: fever, vomiting, failure to thrive.

UTI Symptoms (Children > 1 year old and adults, Lower UTI)

• Painful urination (dysuria).
• Frequent urination (frequency).
• Blood in the urine (hematuria).
• Fever is usually absent (but it may be present in catheterized patients).

UTI Symptoms (Children > 1 year old and adults, Upper UTI)

• Fever (>38.5°C).
• Chills.
• Pain in the kidney area.
• Severe cases: vomiting, diarrhea, tachycardia.

UTI Consequences

• Uro (sepsis): UTI can lead to sepsis and in newborns, 20-30% result in sepsis.
• Renal failure.
• Hypertension.
• Pregnancy and childbirth complications.

UTI Principal Pathogens (Community-acquired)

• E. coli (mostly).
• Staphylococcus saprophyticus.
• Proteus spp.
• Klebsiella spp.
• Staphylococcus spp.
• Enterococcus spp.
• Streptococcus spp.
• Viruses, fungi, and parasites.

UTI Principal Pathogens (Hospital-acquired)

• E. coli.
• Enterobacter spp.
• Proteus spp.
• Serratia marcescens.
• Acinetobacter spp.
• Pseudomonas spp.
• Stenotrophomonas maltophilia.
• Providencia stuartii.
• Staphylococcus spp.
• Enterococcus spp.
• Corynebacterium urealyticum.
• Certain fungi (e.g., Candida spp.).

UTI Diagnosis

• Symptoms.
• Urinalysis (urine strip tests, microscopic observation, flow cytometry).
• Urine sample culture.
• Imaging methods (e.g., ultrasound).
• Blood cultures (in cases of pyelonephritis).

UTI - Urine Examinations

• Microscopy: check for pyuria (white blood cells), hematuria (red blood cells), and proteins.
• Urine strips: detect leukocyte esterase (bacteria), nitrates (bacteria), and pH (identify certain bacteria).
• Culture: determines presence and type of bacterial infection.

UTI - Urine Culture (Diagnosis)

• Recognition of UTI in community-acquired patients: based on symptoms.
• Strip tests/microscopy/flow cytometry of urine sediment: evaluate presence of infection.
• Culture of positive samples: assesses the species of infection.

UTI - Urine Culture (Specimen Collection)

• Midstream urine, clean catch urine.
• Catheter urine samples.
• Bag urines (not recommended for children).
• Suprapubic aspiration (SPA).

UTI - Urine Culture (Storage/Transport)

• Transport to lab within 30 minutes or less.
• Storage (if necessary):
  • Sterile container to 24 hours, 4°C; or to 48 hours, 4°C + boric acid
  • Uromedium (transport-growth medium) at 37°C or room temperature.

UTI - Urine Culture (Microscopic Observation)

• On physician request.
• Presence of > 10⁵ CFU/ml in a urine sample indicates the presence of infection.
• Helpful to determine the cause of sterile pyuria.
• Prepared with unconserved/uncentralized urine sample.

Sterile Pyuria Definition

• Presence of 10 or more white blood cells per microliter of urine in absence of bacteria, diagnosed by aerobic lab techniques.

Sterile Pyuria Reasons

• Antimicrobials.
• Sexually transmitted diseases (STDs) e.g., Gardnerella vaginalis, Mobiluncus spp., Trichomonas vaginalis, Neisseria gonorrhoeae, Chlamydia trachomatis, Ureaplasma urealyticum.
• Tuberculosis.
• Urinary tract injuries.
• Systemic diseases e.g., tumor/cancer, sarcoidosis, hypertension.

Urine Culture Quantitative Examination

• Transport-growth medium (CLED/MCA): used for transport and growth of bacteria, aids in quantifying microbial growth .
• Dilution method: quantifies amount of bacteria in sample (colony forming units per milliliter).
• Hoeprich method: also used for quantitative analysis of bacteria in a urine specimen.
• Colony counts determined.

Contamination of Urine Sample

• Non-invasive specimen collection: less than 10³ CFU/ml.
• Invasive specimen collection: less than 10² CFU/ml.

Significant Bacteriuria (Urine Culture) – Adults

• Midstream urine: >10⁵ CFU/ml (complicated UTIs, recurrent in women, upper UTIs without complications) or > 10³ CFU/ml (lower UTIs).
• Catheter-collected urine: > 10³ CFU/ml (symptoms), >10⁵ CFU/ml (without symptoms).

Significant Bacteriuria (Urine Culture) – Children

• Catheter or suprapubic bladder puncture: ≥5 * 10⁴ CFU/ml (with or without pyuria),.
• Midstream sample with symptoms: ≥10⁵ CFU/ml.

Asymptomatic Bacteriuria (Urine Culture)

• Women: 2 consecutive midstream urine cultures (within 24 hours) with ≥10⁵ CFU/ml in same bacterial species.
• Men: Only one culture with ≥10⁵ CFU/ml of the same species.
• Catheterized patients (men or women): ≥10² CFU/ml.
• Without pyuria.
• Without clinical symptoms.

Asymptomatic Bacteriuria Treatment

• Pregnant women
• Patients before planned surgery in the urinary tract
• Catheterized patients, if bacteriuria persists for 48 hours after catheter removal.

UTI Definitions

• Recurrent UTI: Same bacterial species within 10-14 days after completing treatment or 3 or more uncomplicated UTIs within 12 months..
• Reinfection: Another bacterial species or the same bacterial species within 2-3 weeks after completing treatment.

Prophylactic Measures Against Recurrent Uncomplicated UTI

• Conservative measures (limiting spermicide use, postcoital voiding): not proven effective, but unlikely to harm.
• Cranberry products: Conflicting evidence on effectiveness.
• Continuous antibiotic prophylaxis effectively prevents UTIs.
• Postcoital antibiotic prophylaxis (within 2 hours of intercourse): Effective in preventing UTIs.
• Self-start antibiotic therapy: Safe option for uncomplicated recurrent UTIs; 3-day regimen.
• Vaginal estrogen creams/rings: May reduce UTI risk in postmenopausal women.

UTI Treatment – Lower UTI (First and Second Line Drugs)

• First line: Co-trimoxazole, fluoroquinolones (norfloxacin), nitrofurantoin, furagin.
• Second line: Cephalosporins I (cephalexin, cefadroxil), II generation (cefaclor), fluoroquinolones.

UTI Treatment – Upper UTI (First and Second Line Drugs)

• First line: Co-trimoxazole, fluoroquinolones.
• Second line: Penicillins with beta-lactamases inhibitors, cephalosporins II & III generations

UTI Treatment – Complicated Lower UTI (per os and intravenous)

• First line: Co-trimoxazole, Penicillins with beta-lactamases inhibitors, ciprofloxacin.
• Second line: Penicillins with beta-lactamases inhibitors + aminoglycosides, ampicillin + aminoglycosides, II generation cephalosporins + aminoglycosides.

UTI Treatment – Specific Bacteria (Pseudomonas spp., Gram-positive cocci, Methicillin-resistant Staphylococcus, Enterococcus, and Candida spp.)

• Pseudomonas spp.: Ceftazidime + aminoglycosides, piperacillin/carbenicillin + aminoglycosides, carbapenem + aminoglycosides.
• Gram-positive cocci: Cephalosporins I or II generation + aminoglycosides, penicillins + beta-lactamase inhibitors + aminoglycosides.
• Methicillin-resistant Staphylococcus (MRSA): Glycopeptides.
• Enterococcus spp.: Aminoglycosides + glycopeptides, aminoglycosides + ampicillin.
• Candida spp.: Fluconazole + flucytosine, amphotericin B + flucytosine.

Test your knowledge about urinary tract infections (UTIs), including their causes, defense mechanisms, and predisposing factors. This quiz covers the differences between upper and lower UTIs and highlights critical information relevant to understanding this common condition.