Week 4 - A(1) - Microbiology of Urinary tract infections

Question 1

Name the two gram negative cocci Which organism most commonly causes epididymitis?

Answer 1

Neisseria gohnorrhea and meningitidis Chlaymdia trochomatis is the most common cause of epididymitis

Question 2

What part of the urinary tract is normally colonised with bacteria?

Answer 2

The lower end of the urethra is normally colonised with bacteria

Question 3

The presence of mirco-organsims in the urinary tract causing clinical infection What is this?

Answer 3

A urinary tract infection

Question 4

What is the difference in structures affect by upper vs lower urinary tract infection?

Answer 4

Lower UTI denotes symptoms confined to the bladder and down (cystitis) Upper UTI denotes symptoms affecting the ureter +/- pyelonephritis

Question 5

What are some of the causes of a complicated UTI?

Answer 5

Sepsis or urinary tract abnormalities or stones

Question 6

What is cystitis?

Answer 6

It is the inflammation of the bladder - not always due to infection

Question 7

Bacteriuria = the presence of bacteria in the urine however does not always mean infection What two sets of patients is this most important in?

Answer 7

Does not always mean infection especially in catheterised patients or patients or elderly patients

Question 8

Urinary tract infection (UTI) is common Why is it more common in women rather than men?

Answer 8

Woman have a shorter urethra than men and a closer proximity of the urethral opening to anus

Question 9

What are two types of abnormalities of the urinary tract that can increase the chance of UTI? Also catheterised patients are more at risk

Answer 9

Patient with a horseshoe kidney or posterior urethral valves

Question 10

What is the commonest route of urinary tract infection? Starts of with the bacteria from the bowel and can potentially end up reaching the kidney

Answer 10

This is ascending infection Bacteria from the bowel - perineal skin - urethra - bladder - ureter - kidneys

Question 11

If there is bacteria in the bloodstream, this can be filtered into the kdineys causing infection What is the classical thing described in bacterial bloodstream infection?

Answer 11

Can cause multiple small abscesses

Question 12

What are the most common types of organism causing UTI? What is the most common organism?

Answer 12

Gram negative bacilli - coliforms are the most common type Escherichia coli is the most comon UTI causing organism (accounts for 70% of cases)

Question 13

Apart from E.coli, name 4 other UTI causes and name which is not a coliform?

Answer 13

Can have klebsiella, enterobacter, proteus, enterococcus Also can have pseudomonas aerguinosa causing an infection and this is not a coliform

Question 14

Name a UTI causing organism that is non-lactose fermenting with a positive oxidase test Is this organism a coliform?

Answer 14

Pseudomonas aerguinsa This organism is not a coliform

Question 15

What is the proteus organism associated with the formation of?

Answer 15

Associated with the formation of stones - struvite stones

Question 16

What is the characteristic smell of proteus organisms?

Answer 16

has a foul smelling burnt chocolate odour

Question 17

Proteus has a characteristic swarming culture – multiple concentric ring What can this cause the blockage of?

Answer 17

It can cause the blockage of catheters

Question 18

Describe the features of proteus organism eg * what it causes to form, * what it smells like, * what it looks like on agar plate * and how does it increase urinary pH therefore increasing preciptation of salts?

Answer 18

Causes the formation of struvite (triple phosphate) stones Has a foul burnt chocolate smell has a characterisitc swarming culture Protease produces the enzyme urease which breaks down urea into ammonia increasing urine pH and increasing precipitation of salts

Question 19

Gram negative bacillus but not a coliform Associated with catheters and UT instrumentation What is this?

Answer 19

This is pseudomonas aerguinosa - non lactose fermenter with a +ve oxidative test

Question 20

Pseudomonas is resistant to most oral antibiotics except what?

Answer 20

resistant to most oral antibiotics except ciprofloxacin 4C antibiotics are ciprofloxacin, clindamycin, co-amoxiclav, and cephalosproins (ceftriaxone)

Question 21

What type of organism is enterococcus?

Answer 21

It is a gram positive non-haemolytic streptococci

Question 22

enterocococcus are types of commensals living in the GI tract There is Enterococcus faecalis and Entercoccus faecium Which is not sensitive to antibiotics?

Answer 22

Eenterococcus faecialis is sensitive to antibiotics Enterococuus faecium is not sensitive and therefore harder to treat if a UTI

Question 23

a type of coagulase negative staph usually affects women of child bearing age ? What colour a coagulase negative staph on agar?

Answer 23

This is staph saphrophyticus Coagulase negative staph usually appear white on agar

Question 24

Name the two negative staphlococcal coagulase negative and how do you differentiate beween the two?

Answer 24

Staph epidermis, staph saphrophyticus Novobiocin test Staph saphrophyticus is novobiocin resistant

Question 25

What are symptoms / signs of a urinary tract infection?

Answer 25

Pain on urination Increased frequency of urination Urgency Haematuria

Question 26

female sex, history of UTI, diabetes also and obesity Frequency and urgent urination with suprapubic pain Is this cystitis or pyelonephritis?

Answer 26

This is cystitis, suprapubic pain

Question 27

What are three signs that suggest kidney involvement?

Answer 27

Fever loin pain, rigors

Question 28

What bacteria is the most common cause of UTI? Which is present where there are catheteries and urinary tract abnormalites? Why has a swariming appearance on blood agar? Which infections woman of child bearing age?

Answer 28

E.coli is the most common cause of UTI Pseudomonas aerguinosa is present where there are catheteries and urinary tract abnormalites Proteus has a swariming appearance on blood agar? Staph saphrophyticus infects woman of child bearing age

Question 29

Remember: bladder urine is normally sterile, but urine passed via the urethra will be contaminated with bacteria from the perineum or lower urethra Why is it important when taking a urine sample not to take the first urine passed?

Answer 29

It is the most likely to be contaminated

Question 30

At what stage of urination should the urine sample be taken then?

Answer 30

Take a mid-stream specimen of urine (MSSU)

Question 31

Ideally when taking a mid stream specimen of urine out, the perineum and urethral meatus are washed with?

Answer 31

Washed with saline and not an antiseptic as this can contaminate Give patient a sterile foil bowl First urine passed into toilet Next part collected in foil bowl Last urine passed in toilet

Question 32

When is the only time first void urine is useful?

Answer 32

It is useful when looking for STDs as the cause of the infection

Question 33

What are the two different specimen containers and how long do they last?

Answer 33

Boricon container (red cap) - lasts 24 hours Sterile universal container (white cap) - lasts 2 hours

Question 34

What does the boricon container contain to stop the bacteria multiplying and therefore preserves for 24 hours?

Answer 34

Contain boric acid which is a preservative to prevent multiplication of the bacteria

Question 35

If a patient doesnt have any sympotms of a UTI, should you dipstick test? When should you not dipstick test?

Answer 35

Do not dipstick test unless the patient has symptoms of a UTI Do not dipstick test if the patient has a catheter or is elderly

Question 36

What other things are found in urinalysis in a UTI?

Answer 36

Would find blood, protein and nitrites probably

Question 37

Why would there be nitirites in a UTI? Which bacteria will not cause nitrite in the urine?

Answer 37

Nitirites - due to bacteria breaking down nitrates to nitrites Enterococcus would not indicate the presence of nitrites in the urine

Question 38

In catheter and the elderly, if there is symptoms of a UTI, urinalysis is not carried out Instead what is carried out?

Answer 38

Carry on straight to sending a laboratory sample of urine

Question 39

What is the cornerstone of diagnosis in a urinary tract infection?

Answer 39

Culture of the urine - usually tends to only be one organism causing the UTI

Question 40

As all urine will contain bacteria , it is the concept of “significant bacteriuria”(bacteria in urine) when looking at culture that will indicate a urinary tract infection What is done in urgent cases? (ie a renal transplant patinet)

Answer 40

Microscopy of the urine looking for polymorphs (pus cells), bacteria +/- RBCs