UTIs-Definition

Infectious diseases of the urinary tract: cystitis (bladder) pyelonephritis (kidney) prostatitis (prostate)

Etiology Usually Acute Majority due to a single pathogen Usually an Enterobacteriaceae

90% of all UTI gram negative bacilli common intestinal flora

Escherichia coli most commonly isolated pathogen ~80% of all UTI

Gram staining

Gram –ve E. coli Gram +ve S. aureus

Organisms: Gram -ve

Cause 90-95% of UTI’s most often, E. coli. Others include:

• Proteus mirabilis and Klebsiella.

Gram +ve pathogens include:

• Staph saprophyticus, • Staph aureus, • group A beta hemolytic streptococci and

enterococci.

Features of UTI

Common affliction to seek medical attention.

Infancy to old age Bacturia:

bacteria in urine• does not necessarily

imply infection

Features of UTI Pyuria

Presence of WBCs in urine Evidence of inflammatory response to

infection.

Epidemiology

Populations with increased incidences: School age girls Young women>men

• >50% have a UTI during their lifetime• >10% per year have a UTI • Pregnant women

Elderly of both sexes Diabetes Abnormal urine flow

Who to screen for UTI? Children with recurrent infection Monitoring antibiotic therapy High risk individual

How do we screen for UTIs?

Collect midstream urine use fresh or refrigerate.

Pour about 10 ml in tube and dipstick.

Microscopy Culture

Chemical Analysis Dip-stick testing

Quick Efficient Inexpensive Large number of substances

Chemical Analysis

Chemical Analysis

Chemical Analysis

Urinalysis Dipstick findings:

leukocyte esterase + with pyuria nitrite + with Enterobacteriaceae alkaline pH with urea splitting

bacteria, e.g., Proteus mirabilis high specific gravity if patient is

volume depleted protein often + blood may be +

What are the most useful test? Leukocyte Esterase

Enzyme found WBCs More reliable than microscopic analysis for

WBCs Positive results indicate inflammation in the

path taken by urine.• Includes urethra, prostate, cervix and vagina• Occur in 90 to 95% of symptomatic UTI• Less sensitive asymptomatic UTI in elderly and

pregnancy Significant result: positive

What are the most useful test? Nitrite

Some bacteria will convert Nitrate to Nitrite Good indicator of contact of urine with

bacteria Detects 2/3 to ¾ of all UTIs But…

• Gram +ve bacteria do not cause a positive result• Negative results do not rule out infection

Significant Result: Positive

Microscopic Urinalysis

Urinalysis

Centrifuge for 5 min at 2000 rpm, pour off supernatant; examine sediment with microscope using high power objective.

Microscopic findings: <5 leukocytes per high power field (hpf)

• more = pyuria 1 bacterium per hpf correlates with >100,000

per ml; • 1 bacterium = 1 colony forming unit (cfu)

hematuria

Urine Culture

Quantitative: uncentrifuged urine inoculated on an agar plate to do a colony count.

Appropriate agars: 5% sheep blood and eosin-methylene blue or MacConkey.

Incubate: at 35-37o C for 24 hours.

E. Coli in Urine Culture

Urine Culture Significant bacteriuria:

by 24 hour colony count cystitis: >100 cfu per ml pyelonephritis: >100,000 cfu/ml

Species identification. Susceptibility testing

urine for C&S.

A secure diagnosis of UTI requires a urine culture

How the test is done

Urinary Bacteria Detection Kits Two Uses

Patients susceptible to UTI Monitor effectiveness of Treatment

Detect urinary nitrites associated with gram-negative bacterial infections.

How the Test Works: Nitrites

Gram -ve Pathogen

Nitrite

Diazonium CompoundPink ColorPink Color

N-(1-naphthyl)-ethylenediamine

P-Arsanilic AcidMeat, Fish & Eggs

Nitrate in Acidic Urine

How the Test Works: Leukocytes

Pyrrole Ester Compound

Diazo ReagentColorColor

Leukocyte esterase

INFECTION/INFLAMMATORYRESPONSE

White Blood Cells in Urinary Tract White Blood Cells in Urine

Pyrrole

Sampling precautions Clean Dry Container First Morning Urine or in Bladder >4

hrs Fresh sample Follow-up: Regardless of result. Test Sensitivity

90% - 3 consecutive mornings 10% - False negative rate

Factors Affecting Test Concentration of Gram -ve Bacteria

> 100,000/mL of urine Time in the Bladder Contamination Blood Adequate Dietary Nitrates

Most people Consume sufficient Quantities Drug interference

Alkaline Urine Ascorbic Acid (Vitamin C)>250 mg Antibiotics and Drugs that turn urine red

Home Cholesterol Tests

Two Uses Monitor progress on Lipid lowering drugs and diet Save Time and Costs of Physician Visits

Err on the side of false positives Multiple measurements should be

evaluated Measurement errors and day to day

biological and behavioral changes contribute to variations in cholesterol levels

How the Test Works

Filter

Few Drops of Blood

Plasma (Cholesterol & Cholesterol esters)

Cholest-4-ene-3-one H2O2 Colored Dye

Step 1

Step 2a1. Wick Flow of Plasma2. Cholesterol Oxidase/Esterase

Step 2b

Peroxidase

10

3.2

Factors Affecting TestFactors Affecting Test

Finger Pricking Technique Hanging Drops Squeezing and Milking

Time to Collect Low results if > 5 min.

Blood Volume

?Usefulness Test only measures Total Cholesterol Laboratories measure LDL, HDL,

triglyceride, and cholesterol. All are required. You cannot make a judgement on

cardiovascular risk on Cholesterol alone. If values >5.2 : Discuss with physician If values<5.2: Check Cholesterol again at next

visit with a physician

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complications

This new product measures cholesterol plus other things using a test strip

Predict in as greatest detail you can how it might works…

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