Microbiology for Health Science FHS 204: UTIs

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Questions and Answers

A urine sample containing a single species of Enterobacteriaceae at a count of 100 cfu/ml is considered a significant infection.

False (B)

Which of the following urine sample collection methods is considered controversial when evaluating for a urinary tract infection (UTI)?

  • Obtained by straight catheterization
  • Controversial (correct)
  • Surgery or bladder aspirate
  • Voided, clean-catch

A urine sample containing more than two species of potential pathogens is considered to have ______.

mixed flora

Which of the following is NOT a common causative agent of Urinary Tract Infections (UTIs)?

<p>Staphylococcus aureus (C)</p> Signup and view all the answers

What is the minimum number of colony-forming units (cfu) per milliliter of urine that is considered significant for a UTI?

<p>10 cfu/ml</p> Signup and view all the answers

The bladder and kidneys are normally sterile.

<p>True (A)</p> Signup and view all the answers

Match the following urine sample collection methods with their appropriate minimum count for potential pathogens:

<p>Voided, clean-catch for females = 100 cfu/ml Voided, clean-catch for males = 1,000 cfu/ml Obtained by straight catheterization = 100 cfu/ml Surgery or bladder aspirate = Any number of species of potential pathogens Controversial = Any isolates of yeast</p> Signup and view all the answers

What is the name of the condition where a UTI spreads to the bloodstream?

<p>Urosepsis</p> Signup and view all the answers

The most common causative agent of UTIs is ______.

<p>Escherichia coli</p> Signup and view all the answers

Which of the following is a host defense mechanism against UTIs?

<p>All of the above (D)</p> Signup and view all the answers

Match the following symptoms with the corresponding type of UTI:

<p>Dysuria = Lower UTI Flank pain = Upper UTI Fever and chills = Upper UTI Frequency of micturition = Lower UTI Nausea and vomiting = Upper UTI</p> Signup and view all the answers

A UTI is a sexually transmitted infection (STI).

<p>False (B)</p> Signup and view all the answers

What is the name of the barrier formed by the bladder mucin layer that helps prevent bacteria from adhering to the bladder mucosa?

<p>Mucin layer</p> Signup and view all the answers

Which of the following is NOT a contributing factor to urinary tract infections (UTIs)?

<p>Blood Type (B)</p> Signup and view all the answers

Urosepsis occurs when a localized urinary tract infection spreads to the bloodstream, causing a systemic infection.

<p>True (A)</p> Signup and view all the answers

What are two common primary pathogens associated with UTIs?

<p>E. coli and Proteus</p> Signup and view all the answers

The ______ of a urine sample is a critical factor in determining the presence of a UTI.

<p>culture</p> Signup and view all the answers

Match the following terms with their corresponding descriptions:

<p>Urosepsis = A systemic infection resulting from a urinary tract infection spreading to the bloodstream Vesico-ureteral reflex = Abnormal flow of urine from the bladder back up the ureters to the kidneys Catheterized urine = Urine collected using a sterile tube inserted into the bladder Indwelling catheter = A long-term tube inserted into the bladder for drainage Suprapubic aspiration = Urine collected by inserting a needle directly into the bladder through the abdominal wall</p> Signup and view all the answers

Which of the following is NOT a treatment option for urosepsis?

<p>Antiviral medications (D)</p> Signup and view all the answers

Females are more prone to UTIs than males due to their longer and narrower urethras.

<p>False (B)</p> Signup and view all the answers

Explain why older individuals are more susceptible to UTIs.

<p>Older adults are more vulnerable to UTIs due to factors like weakened immune systems, decreased bladder function, and increased risk of underlying health conditions.</p> Signup and view all the answers

A ______ is a tube placed in the bladder for long-term drainage.

<p>indwelling catheter</p> Signup and view all the answers

Which of the following urine samples is considered the most reliable for diagnosing a UTI?

<p>Suprapubic aspiration (C)</p> Signup and view all the answers

Flashcards

Urosepsis

A systemic infection from a urinary tract infection that enters the bloodstream.

Antibiotics for UTI

Medications used to treat urinary tract infections by killing or inhibiting bacteria.

Low BP management

Methods to treat low blood pressure in urosepsis, including IV fluids and vasopressors.

Clean catch urine

A method for collecting urine to reduce contamination for laboratory testing.

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Neurogenic bladder dysfunction

Bladder problems caused by nerve damage, increasing UTI risk.

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Vesico-ureteral reflex

Abnormal urine flow from the bladder back to the kidneys, causing infections.

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Primary pathogens in UTI

Common bacteria causing urinary tract infections, like E. coli and Staphylococcus saprophyticus.

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Urine culture incubation

A lab test to identify bacteria in urine by growing them in controlled conditions.

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Significant pathogen CFU/ml

A measure indicating bacterial presence in urine, determining infection significance.

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Criteria for evaluating urine cultures

Standards to determine if urine culture results indicate an infection based on pathogen quantity.

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Urinary Tract Infection (UTI)

Infection characterized by significant microorganisms in the urinary tract.

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Common UTI Pathogens

Gram-negative rods, primarily Enterobacteriaceae, causing UTIs.

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Lower UTI Symptoms

Frequency of urination, pain during urination, blood-stained urine.

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Upper UTI Symptoms

Includes lower UTI symptoms plus flank pain, fever, and chills.

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Cystitis

Bladder infection causing dysuria and urinary urgency.

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Pyelonephritis

Kidney infection that can cause lasting damage and scarring.

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Common UTI Antibiotics

Trimethoprim, Fosfomycin, Nitrofurantoin, among others.

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Contaminated Urine

Urine is considered contaminated if it has >2 species present.

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Voided Clean-Catch

A method for urine collection minimizing contamination by external flora.

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Significant UTI Indicator

≥10 cfu/ml of urine is a significant indicator of a UTI.

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Mixed Flora

Presence of >2 pathogens leads to classification as mixed flora.

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Pathogen Reporting

If more than 2 pathogens are present, they should be reported.

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Study Notes

Microbiology for Health Science FHS 204

  • Systemic infections are covered, including bacteriology
  • Microbes interact with various body systems
  • Urinary Tract Infections (UTIs)
    • Microorganisms are present in abundance in the urinary tract
    • Kidneys and bladder are normally sterile
    • Host defense mechanisms include: urination, bladder mucin layer to prevent bacteria adherence, and secretory IgA

UTI: Aetiology

  • Common causative agents of UTIs are gram-negative rods, mostly enterobacteriaceae
    • Enterobacteriaceae are a large, diverse group of gram-negative rods
    • Common pathogens include Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Proteus species.
    • Other important causative agents are Enterococci and Staphylococcus saprophyticus (a common pathogen in sexually active young women)

Clinical Features

  • Lower urinary tract infection (LUTI) involves urethra and bladder, characterized by frequent urination, pain during urination, blood-tinged or cloudy urine, suprapubic tenderness, malaise,and foul-smelling urine. Often no fever
  • Upper urinary tract infection (UTI) involves kidney parenchyma. Symptoms include those of LUTI plus flank pain, fever, chills, nausea, vomiting, and flank tenderness

Infections of the Urogenital Tract: Urinary Tract Infections

  • Urethritis: Infection of the urethra and causes dysuria (painful urination)
  • Cystitis: Infection of the bladder and causes dysuria
  • Pyelonephritis: Infection of the kidney and causes scarring and kidney damage

Antibiotics commonly used for simple UTIs

  • Trimethoprim and sulfamethoxazole (Bactrim, Bactrim DS)

  • Fosfomycin (Monurol)

  • Nitrofurantoin (Macrodantin, Macrobid, Furadantin)

  • Cephalexin

  • Ceftriaxone

  • UTIs are not sexually transmitted infections (STIs)

Urosepsis

  • A complication of UTI.
  • When the infection spreads to the bloodstream, causing a systemic infection, urosepsis results
  • Treatment involves antibiotics and management of hypotension, if present through intravenous fluids, and vasopressin (Pitressin) and corticosteroids.

UTI Laboratory Diagnosis

  • Specimen types include: clean-caught midstream urine, catheterized urine, and suprapubic aspiration

Instructions for Giving Urine Specimen

  • Proper handwashing is crucial
  • Clean the genital area
  • Collect urine in a sterile container (avoid contamination)

Contributing factors for Urinary Tract Infection

  • Age (very young and very old individuals are at higher risk)
  • Gender (UTIs are more common in females)
  • Urinary catheterization or cystoscopy procedures
  • Neurogenic bladder dysfunction(e.g., diabetes mellitus, spinal injury)
  • Obstruction (e.g., congenital anomalies, prostatic adenoma)
  • Underlying diseases (e.g. diabetes mellitus, sickle cell disease)

Urine Culture

  • Collect midstream urine
  • Plate onto appropriate agar (BAP and MacConkey) for Gram positive and Gram negative rods
  • Incubate for 24 hours to detect various pathogens
  • Identification of pathogens according to their colony characteristics (colour and appearance on the plate)

Interpretation of culture results

  • 102 or more colony forming units/ml of urine indicates UTI.
  • <103 colony forming units/ml of urine may indicate contamination of the specimen.
  • 103-105 colony forming units/ml of urine is inconclusive and requires further consideration and clinical input

Diagnosis of Urinary Tract Infections: Interpretation

  • Calculation of CFUs/ml depend on the volume of urine plated (using sterile calibrated loops) and number of colonies observed on the plate
  • CFUs/ml = number of colonies/volume plated

Chemistry (Urine)

  • Assessment of urine using dipstick tests (pH, Nitrite, Leucocytes,Specific gravity, Ketones, Glucose, Bilirubin, Urobilinogen, Proteins)
  • Key aspects to interpret dipstick results (abnormal values and correlation to infection).

Reject Urine Samples If

  • Urine is older than two hours, without refrigeration.
  • From a catheterized patient.
  • Improperly labeled.
  • From a leaky container, from a homemade container.
  • Contaminated with hair/feces/menstrual blood.
  • Collected when on antimicrobial therapy
  • During menstruation
  • Collected from a bed pan or urinal
  • Frozen sample
  • 24-hour urine collections.

Case Study

  • Scenario: a 24 year old woman with painful urination for 24 hours, a fever of 39°C, and persistent urge to urinate

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