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MedEd + PathSoc + Laz's Qs + Romesh Path > Microbio 6: UTI > Flashcards

Microbio 6: UTI Flashcards

1
Q

UTI definitions?

A

WCC in urine >10^5 - 1 predominant organism in mixed growth

WCC in urine >10^4 - if just 1 organism (no mixed growth)

WCC in urine >10^3 - if E.coli or Staph. Saprophyticus

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2
Q

What is a Lower UTI?

A

Infection of the bladder (aka cystitis) usually caused by bacteria from the GIT

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3
Q

What is a Upper UTI? AKA?

A

Infection of the upper part of the urinary tract —the ureters and kidneys (pyelonephritis)

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4
Q

What is a recurrent UTI?

A

Usually defined as two or more episodes of UTI in six months

OR three or more episodes in one year.

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5
Q

What is a catheter assocaited UTI?

A

Symptomatic infection of the bladder or kidneys in a person who is catheterised or who has had a urinary catheter in place within the previous 48 hours

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6
Q

What is bacteriuria?

A

The presence of bacteria in the urine — may be asymptomatic (only significant / requires mx if pregnant)

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7
Q

How can lower UTIs be categorised?

A

Uncomplicated UTI— Infection in a structurally and neurologically normal urinary tract + nopredisposing co-morbidities.

Complicated UTI—Infection in a urinary tract with functional or structural abnormalities (includes indwelling catheters and calculi)
RFs: structural or neurological abnormalities of the urinary tract, catheters, virulent/ atypical infecting organisms, poorly controlled diabetes mellitus or immunosuppression.

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8
Q

How can obstruction cause UTIs?

A

Inhibits urine flow → stasis → infection

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9
Q

How can obstructions that cause UTIs be categorised?

A

Extrarenal

Intrarenal

Neurogenic malfunction

Vesicoureteral reflux - Residual pool of urine in bladder → ureters → renal scarring in children

Haematogenous spread - S. Aureus bacteraemia / endocarditis → renal abscess

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10
Q

What are some examples of extrarenal obstructions that can lead to UTIs?

A

Valves, stenosis or bands

Calculi

BPH - tumour compression

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11
Q

What are some examples of intrarenal obstructions that can lead to UTIs?

A

Nephrocalcinosis

Nephropathy (uric acid, analgesic, hypokalaemic)

Polycystic kidney disease

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12
Q

What are some examples of neurogenic malfunction caused obstructions that can lead to UTIs?

A

Poliomyelitis

Tabes dorsalis (demyelinating condition caused by advanced syphilis)

Diabetic neuropathy

Spinal cord injuries

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13
Q

What organisms commonly cause UTI in children w/ vesicoureteric reflux?

A

E. coli and S. saprophyticus

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14
Q

What organisms cause UTIs?

A

E. coli - MOST COMMON
S. Saprophytics - 2nd MOST COMMON (esp young women)

Proteus mirabilis
Pseudomonas
Candida
Klebsiella aerogenes
Enterococcus faecalis
Staph epidermis
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15
Q

What organism is likely to cause UTIs in individuals w/ kidney stones (particularly struvite / staghorn calculi)?

A

Proteus Mirabilis

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16
Q

What organisms are likely to cause UTIs in individuals w/ catheters?

A

Pseudomonas and Candida
+
Staphylococcus epidermis - coagulase -ve

17
Q

What organisms are likely to cause UTIs in people with abnormal tracts? what is its virulence factor?

A

Klebsiella aerogenes - K-antigen

18
Q

What is the virulence factor of the 2 most common causes of UTIs?

A

E. Coli - P-fimbrae

S. Saprophyticus - P-fimbrae, this bacteria is coagulase -ve

19
Q

What are the causes of sterile pyuria (white cells in urine)?

A

Abx treatment (most common)

Calculi

Catheter

Tumour

TB

STD

20
Q

Who is more likely to get UTIs and why?

A

Women are more prone to UTIs than men because they have shorter urethras and so contamination from the rectum is easier to ascend

21
Q

What would you depending on the different results of urine dipsticks?

A

Leuc +ve, nit +ve = UTI, start abx

Leuc -ve, nit +ve = Start Abx, further mx guided by MC&S

Leuc +ve, nit -ve = Only start Abx if clinical evidence of UTI

Leuc -ve, nit -ve = UTI unlikley - consider other dx

22
Q

What are some different results that you can get in MC&S that shows contamination of sample?

A

Squamous epithelial cells - unable to culture organism due to contaminated smaple
+ mixed growth = contamination of sample

23
Q

Tests for UTIs

A

Urine dip + MC&S
Bloods - FBC, U+E, CRP and WCC
Further = Renal USS, IV urography (in complicated UTIs)

24
Q

List some patient groups in whom culture and sensitivities should be performed?

A

pregnant, child, pyelonephritis, men, catheter, failed Abx, abnormal tract, renal impairment

Sensitivities: disc diffusion, zones of inhibition

25
Q

What is mx of UTIs?

A

3 typical symptoms and no vaginal discharge = empirical treatment 3 days
- If recurrent/ atypical (Abx-resistant)/ > 7 days symptoms/ male = 7-day Abx course

≤ 2 symptoms → urine sample + dipstick

1st Line = Nitrofurantoin or Trimethoprem due to low risk of resistance

26
Q

Which UTI drugs should be avoided during pregnancy and why?

A

Trimethoprim contraindication in 1st trimester → folate antagonist

Nitrofurantoin should be avoided in 3rd trimester → neonatal haemolysis

27
Q

UTI mx if EBSL producing organism?

A

Outpatient parenteral antimicrobial therapy

28
Q

Mx of UTI in a person w/ a catheter?

A

Gentamicin/ Amikacin 140mg), remove catheter (biofilm)

29
Q

Mx of Pyelonephritis?

A

Broad spec IV Abx eg: Co-amoxiclav/ Cefuroxime ± Gentamicin

30
Q

Who is at greater risk of candida infection? mx of this?

A

Patients with indwelling catheters

Only treat if renal transplant/ urinary tract surgery

Remove catheter (MOST IMPORTANT)
1st line - PO fluconazole,
2nd line - non-liposomal amphotericin B

31
Q

What is vesicoureteric reflux?

A

A condition in which urine can reflux into the ureters

It results in a residual pool of infected urine in the bladder after voiding
It can result in scarring of the kidneys

32
Q

What type of agar is used for urine culture? What do the colours suggest?

A

Chromogenic agar:
Pink = E. coli
Blue = other coliforms
Light blue = Gram-positives

33
Q

In which groups of patients is a short course of antibiotics not appropriate?

A

Women with a history of UTI caused by antibiotic resistant organisms

More than 7 days of symptoms

Men

34
Q

List some complications of pyelonephritis

A

Perinephric abscess

Chronic pyelonephritis (scarring, renal impairment)

Septic shock

Acute papillary necrosis

35
Q

Which part of the kidney is more susceptible to infection?

A

Renal medulla

36
Q

Most common cause of UTI in young women?

A

E. Coli

then comes Staph saprophytics

37
Q

Why should nitrofurantoin be avoided in late pregnancy?

A

Neonatal haemolysis

MedEd + PathSoc + Laz's Qs + Romesh Path (99 decks)

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