UTIs Flashcards by Nora Elena Sondresen Kvam

What is the classical presentation of UTI?

Lower abdominal pain

Frequent and urgent need to urinate

Little urine

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What is another name for UTI?

Acute cystitis

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What is a UTI?

Bacterial infection of the bladder

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What is a rare complication of a UTI?

Can ascend to the kidneys causing pyelonephritis

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What are diagnostic methods of UTIs?

Dipsticks

Examining urine characteristics

Microscopy

Culture

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Why are antibiotic sensitivity tests important when treating UTIs?

Many uropathogens are resistant to common antibiotics

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UTI is one of the most common infectious diseases in the world

TRUE or FALSE

TRUE

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Why are UTIs more common in women than men?

Outside environment is closer to the female anatomy

Urethra is much shorter in women than men

Easier for pathogens to reach the bladder in females

Bacteria present in faeces or skin of the perineum of the anus may find their way to the distal urethra

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What proportion of females in the UK will develop a UTI at some point in their life?

Up to half of all women in the UK

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What proportion of men develop a UTI in the UK yearly?

1 in 2000 healthy men

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What is the length of the urethra in women?

4-5 cm

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What is the length of the urethra in men?

20-25 cm

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What are common causes and risk factors of UTIs in males?

Enlarged prostate

Kidney stones

Catherisation

Weakened immune system

Diabetes

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How does an enlarged prostate increase the risk of developing UTIs in males?

Prevents the bladder from fully emptying

Causes urine to stagnate

Allows bacteria to multiply

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How does diabetes increase the risk of developing UTIs in males?

Glucose which may be present in the urine supports the growth of bacteria

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What are common causes and risk factors of UTIs in females?

Factors which prevent full emptying of the bladder

Catherisation

Weakened immune system

Diabetes

Being sexually active

Spermicide

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What are factors that prevent full emptying of the bladder in females?

Kidney stones

Using contraceptive diaphragm

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Are UTIs sexually transmitted diseases?

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How does being sexually active increase chances of developing UTIs?

Sex can irritate the urethra

Allows bacteria to enter more easily

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How does spermicide increase the chances of developing UTIs?

Can irritate the vagina and reduce its immune defences

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Is voided urine sterile?

Yes

Sterile or have low levels of bacteria

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How does the vagina prevent bacterial contamination of the urethra?

Immune defences

Flushing with urine - bladder is constantly washed out and emptied

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What has recent evidence showed about the environment of the bladder?

Originally thought there was no bacteria in the bladder

Recent work shows bladder may normally harbour some bacteria

Can now see them due to molecular techniques like sequencing and PCR

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What is cystitis?

Infection and inflammation of the bladder

Causes the discomfort and pain associated with UTIs

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What is pyelonephritis?

Infection can spread from the bladder via the ureters to infect the kidneys Happens in minority of patients

What is the main symptom of pyelonephritis?

Pain in the lower back

What are possible complications of pyelonephritis?

Renal failure Septimcaemia

What percentage of all nonconsomial infections are UTIs?

40%

Which population is particularly at risk of developing UTIs?

Catherised Undergo cystoscopy

What is the sample taken to test for UTIs?

Midstream specimen of urine First 20 ml of urine should be passed into the toilet and a sample should be collected midstream into a sterile container

Why should a midstream specimen of urine be collected for UTI testing?

Prevent the initial urine from picking up bacteria from the skin

What volume of urine is required for UTI testing?

5-10 ml of urine

How should the patient prepare before taking urine sample?

Patient should wash around their genital area first with soap and water

When is lab testing of urine not necessary?

If patient is in pain/ cloudy urine

What does a dispstick urinalysis indicate?

Presence of several markers of urinary tract

What are the key features of UTI that show up on dispstick urine test?

Leukocytes Nitrites Blood Glucose Urobilinogen

Why is a nitrite dipstick urine test inaccurate?

Not all bacteria produce nitrites Only gram negative Break down urine to form nitrite

What is pyuria?

Presence of pus in the urine

Why are urobilinogen levels elevated in YTI?

Due to haemolytic processes

How does the presence of blood show up in a urine dipstick test?

Haemoglobin released from haemolysed RBC causes a colour change from yellow to green Intact red cells cause intense green speckles

What are the advantages of urine dipstick analysis?

Quick Cheap

What are the disadvantages of urine dipstick tests?

Leukocyte esterase misses some geniune infections - Especially if they are subacute - Not very specific Nitrite test is only applicable to bacterial species that reduce nitrate - E. coli

What is an example of uropathogen that does not reduce nitrates?

Enterococcus

What happens if urine dipstick test shows up negative with the presence of UTI symptoms?

Further tests are warranted

What are macroscopic inspections we can do of urine?

Turbidity - indicates pyuria Haematuria Foul smell

What causes the turbidity of the urine?

Neutrophils Recruited to the site of infection in the bladder

What is observed during microscopic inspection of urine?

Light microscope Inspected for presence of white and red blood cells Normally present in very low numbers When high = strongly indicative of UTI

What is the third lab test we can do on urine to identify UTI?

Culture

How is culture used to diagnose UTI?

Confirmates and identifies bacterial infection By culturing the urine on an agar plate

How is a culture carried out

A volume of 1-10μl of urine is spread on agar plate Placed in an aerobic incubator at 37 degrees for 24 hours Viable bacteria present will grow into colonies

How is culture used to diagnose UTI?

Count the bacterial colonies

What is an example of a modification of culture used in labs to identify bacterial species in urine?

Chromogenic agar Imparts different colony colours to different uropathogens Useful to distinguish what type of bacteria you have

Where are sources of bacteria in urine?

From the skin may be introduced during the urine sample collection Distal urethra Bladders

Does presence of bacteria in urine immediately indicative of UTI?

No Small numbers of bacteria in urine is normal

What is the threshold for significant bacteriuria in many european countries?

10^5 bacteria/ ml urine

Why do some countries have lower thresholds for significant bacteriuria?

Recognise that an arbitrary cutoff of 10^5 may not make sense for all patients Arbitrary threshold would exclude a proportion of the population with the disease

What are non-acute symptoms indicative of low-count UTI?

Frequency Urgency Incontinence

What percentage of acute UTIs is E.coli responsible for?

E. coli

What are most acute UTIs characterised by?

Caused by a single type of bacteria

What may mixed bacterial growth be indicative of?

Contamination during sample collection

UTIs cannot be caused by mixed bacterial growths TRUE or FALSE

FALSE Mixed growths can be significant Especially in chronic or subacute UTI

What is the disk diffusion method?

Test to see if the pathogen being treated is sensitive to abtibiotics

When are disk diffusions carried out?

When urine culture finds a significant bacteriuria

Why are disk diffusion methods carried out?

To determine the specificity or resistance of the strain to a range of antibiotics

How do you carry out a disk diffusion method?

Colonies are picked from the first culture plates They are re-inoculated onto a new agar plate Antibiotics impregnated in paper discs are placed on the agar plate

How long are disk diffusion agar plates incubated?

48 hours

How do we use the results of the disk diffusion method to conclude sensitivity of the bacteria to antibiotics?

Look at zone of inhibition If the disk is secreting antibiotic that forms a zone of inhibition = bacteria is sensitive to it

What is a disadvantage of bacterial culturing?

Takes time Delay diagnosis and treatment Can take up to 2 days When a UTI is strongly inspected following microscopy, the initial culture step can be missed out Move straight on to antibiotic sensitivity testing

What are examples of automated microbial identification and antimicrobial susceptibility testing systems (AST) being used?

Biotyper BD Phoenix

What is a biotyper?

Microbial identification system based on protein signatures Matrix-assisted laser desorption ionization Time of flight mass spectrometry

What is a form of treatment of UTIs?

Empirical use of antibiotics Take any broad-range antibiotic and hope it works