Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MICRO ADYA > Microbiology 10 - Urinary Tract Infections > Flashcards

Microbiology 10 - Urinary Tract Infections Flashcards

1
Q

Which organism is the most common cause of UTI in structurally normal people

What increases the virulence of E. Coli?

A

E coli O serotype-

Virulence factors e.g. P-fimbriae - allows them to attach to the epithelium and ascend to the bladder or the kidneys

NB: most UTIs are caused by a single bacterium (if you get mixed, tends to be in structurally abnormal urinary tract)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the empirical antibiotic treatment for pyelonephritis?

A

Co-amoxiclav +/- gentamycin

Amikacin is also recommended as most ESBLs are sensitive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

When is it iimportant to treat bacteruria and why?

A

Usually it is not a cause for concern, but in pregnant women it can lead to complications- hence must treat.

complications- LBW, prematurity, pre-eclampsia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is a complicated UTI?

A

infection in a urinary tract with functional or structural ABNORMALITIES

iatrogenic- indwelling catheters, stents

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

WHat is the second most common cause of UTIs in women?

A

Staphlococcus saprophyticus

It has virulence Pfimbriae- allows it to ascend

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Which organism tends to affect structurally abnormal kidney tracts and is associated with kidney stones?

A

Proteus Mirabilis

*also Klebsiella

PK

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Which organism causes UTIs in the presence of prosthetic material eg longterm indwelling catheter?

A

Staph epidermidis - usually a common skin commensal

**another coagulase negative staph (like saprophyticus)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Which organisms are implicated in recurrent UTIs? What properties do they share?

A

These organisms can adhere to prosthetic material like indwelling catheters eg pseudomonas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What makes ascending infection likely?

A
  • structural abnormlaities eg VUR- allows urine to reflux into ureters and possibly kidneys
  • bacterial factors - E Coli and S. Saprophyticus have virulence factors –> adherence to epithelium enables ascent
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

In females where do bacteria tend to colonise before they cause UTIs?

A
  • vaginal introitus
  • periurethral area
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What can cause staph aureus to be present in urine? Thus what must you do if you find staph aureus in urine?

A

a) poorly taken sample - contaminant in perineal/ groin area: REPEAT SAMPLE
b) endocarditis / bacteraemiea/emboli –> spread of staph aureus to the kidneys–>bladder–> urine
* SIGN OF STAPH AUREUS ABSCESS IN THE KIDNEY: TAKE BLOOD CULTURES

NB: staph aureus does NOT ASCEND the urinary epithelium as it doesn’t have virulence factors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How does the route of spread of gram positive and gram negative organisms differ?

A

Gram negatives- ascend the urinary epithelium (eg E Coli )

Gram positives - spread haematogenously (eg staph auerus)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the two main renal tract abnormalities that can cause UTIs?

A
  1. obstruction - can be extrarenal or renal:
    * Obstruction INHIBITS the normal flow of urine >>> stasis** >>> **increasing susceptibility to infection
  2. reflux - VUR in children: maintaining a residual pool of infected urine in the bladder after voiding >>> cause scarring of kidneys
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Symptoms of UTIs in <2yo?

A

Failure to thrive

Vomiting

Fever

**basc very non-specific

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Symptoms of lower UTI?

A
  • frequency
  • dysuria
  • small amounts of turbid urine
  • suprapubic heaviness OR pain
  • Sometimes haematuria
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What does presence of fever in UTI indicate?

A

Only get fever in UPPER UTI

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Symptoms of an upper UTI

A
  • Fever (sometimes with rigors)
  • Flank pain
  • lower tract symptoms (e.g. frequency, urgency and dysuria)
    • lower UTI may precede upper UTI by 1-2 days as the infection ascends
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

SYmptoms of UTI in older patients

A

mainly ASYMPTOMATIC

Symptoms of upper tract infection are often atypical

e.g. vague abdominal pain, change in mental status

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

IVX for UTIs

What else do you need to do for complicated UTIs?

A
  • Bloods
    • FBC- WCC
    • CRP
    • U&Es
  • MSU for MC&S
    • Microscopy: look for RBC and WBC
    • Culture
    • Sensitivities- disc diffusion \

Complicated UTIs:

  • renal ultrasound
  • IV urography
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

how do you make sure there’s no contamination of MSU sample?

A

midstream urine sample

Look for presence of squamous epithelial cells (from the urethra) - these look like FRIED EGG CELLS under microscope

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What does the presence of fried egg cells on microscopy suggest?

A

Contamination with squamous epithelial cells from the urethra

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

When do you ask elderly/frail people to do a urine sample

A

ONly if they are symompatic and are able to collect a urine sample

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are the indications to send a urine sample for culture?

A
  • over 65 if symptomatic and antibiotic given
  • pregnancy
  • suspected pyelonephritis or sepsis
  • suspected UTI in men
  • failed Abx Tx or persistent sx
  • recurrent UTI
  • prescribing Abx in someone with a urinary catheter
  • abnormalities of genitourinary tract
  • renal impairment
  • care home resident
  • hospitalisation for >7 days in last 6m
  • recent travel to a country with increased resistance
  • previous UTI resistant
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

How do you define recurrent UTI?

A

2 episodes in 6 months

or 3 episodes in 12 months

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

How quickly must you culture urine and why?

A

Within 4 hours as it then increases the chance of false positives.

26
Q

WHat is added to a urine sample before sending for culture, to preserve the sample?

A

Boric acid- must fill to the correct line: stabilise the bacteria and so avoids overgrowth, preserves cells and prevents false positives

*can also refrigerate the sample

27
Q

What would you do if you found asymptomatic bacteruria after culture?

A

only treat if pregnant

28
Q

What is the CFU cut off for UTI? (general)

A

Path guide: culture of >10^4 colony forming units / ml is diagnostic (10^3 for E. coli / S. saprophyticus

Lecture (see picture)

29
Q

What is the CFU cut off for UTI in strongly symptomatic women?

A

10^5 CFU/L

30
Q

What do you do if you find mixed growth on culture?

A

Repeat!

As it could be a contaminant or a genuine mixed infection

31
Q

What does RBC found on microscopy mean? and what type of UTI is it seen in more

A

Can happen in lower or upper UTIs (though it’s more common in upper UTIs)

*if you get recurrent haematuria post-infection, refer to urology

32
Q

What is sterile pyuria and what can this indicate (4) ?

A

When you find WBC but no bacteria on culture

Think of:

  • TB
  • chlamydia: inflammation of urethra + other STIs
  • renal pathology:
  • calculi- can cause inflammation
  • Bladder neoplasm / Catheterisation
  • The MOST COMMON CAUSE of sterile pyuria is due to prior antibiotic use
33
Q

Specific diagnostic points for men

A
  • have lower threshold for concern
  • consider prostatitis and STIs
  • always send MSU for culture BEFORE antiobiotics
  • NB: dipsticks are not accurate at picking up infection
  • Recurrent UTIs - refer to urology
  • men <65 years, if suspected UTI offer mediate treatment and tailor antibiotic based on culture results
34
Q

How does prostatitis present?

A

Fever

Back pain

Rectal pain

Lower UTI symptoms

Prostate tenderness on DRE

35
Q

Diagnostic protocol for UTI in women <65

A
36
Q

Do you do a dipstick in >65 yo?

A

No- becomes less accurate with age

37
Q

Diagnostic protocol for UTIs in >65s

A

*basc consider other causes before jumping straight to UTI

38
Q

Mnemonic for causes of delirium

A

PINCH ME

Pain

Infection

Nutrition

Constipation

Hydration

Medication

Environment

39
Q

Empirical treatment for UTIs in community and duration

A

Nitrofurantoin is first line for uncomplicated UTI

*Not trimethorpim because of increasing resistance (a lot of e coli is now resistant to trimethoprim)

*Short course: 3 days for uncomplicated UTIs in women

*Longer course in: 7 days for 1) men, 2) women with symptoms >7 days, 3) women with previous history of UTIs with resistant organisms

40
Q

When must you take nitrifurantoin and why?

A

After emptying bladder

As it stays in bladder, not systemically absorbed

41
Q

Which antibiotics are contraindicated in pregnancy?

A

Nitrofurantoin- only at term and during breasfeeding - haemoyltic anaemia in babies

Trimethoprim- always contraindicated (mainly in first trimester)- neural tube defects

42
Q

Antibiotics for catheter associated UTIs

A

Unlikely to resolve unless catheter is removed

STAT doses of aminoglycoside are recommended and can be given BEFORE REMOVAL of an infected catheter

Gentamicin (80mg STAT IV/IM) or

Amikacin (140mg STAT IV/ IM)

43
Q

Which groups of patients get fungal UTIs?

A

Generally in people with indwelling catheters

Because fungi produce biofilm

44
Q

Treatment of fungal UTIs

A

PO fluconazole –> if no improvement then non-liposomal amphotericin B

*NB: difficult to treat as many antifungals don’t get excreted by kidneys

45
Q
A
46
Q

When do you do imaging for pyelonephritis?

A

All men

And women with second presentation of pyelonephritis

47
Q

Overall what features would suggest contamination of urine sample?

A

Mixed growth

Squamous epithelial cells

48
Q

what does mixed growth indicate in UTI

A

structural abnormality or contamination so repeat sample first

49
Q

groups of people likely to have complicated UTIs

A

men- should not be having UTI due to long urethra

pregnant women- gravid uterus can cause obstruction

young children- recurrent UTI can indicate strucutal abnormalities

hospitalsed patients i.e. due to indwelling catheters/stents

50
Q
A
51
Q

common organisms when there is another problem in the urinary tract

A
  • proteus mirabilis: stones
  • Klebsiella aerogenes- abnormal urinary tracts (i.e. stones, neurological or anatomical abnormalities) + patients who are catheterised
  • Enterococcus faecalis: hospital admited patienets
  • Staphylococcus saprophyticus- 2nd commonest cause of UTI in young healthy women (but also associated into indwelling lines etc)
  • Staphylococcus epidermidis: cause UTI in presence e.g. instrumentation procedures or long-term indwelling catheterof prosthesis - IATROGENIC
52
Q

extrarenal causes of obstruction that cause UTI

A
  • Valves
  • Stenosis or bands
  • Calculi
  • Extrinsic ureteral compression from a variety of causes e.g. BPH or gravid uterus in pregnancy
53
Q

intrarenal causes of obstruction that cause UTI

A
  • Nephrocalcinosis
  • Uric acid nephropathy
  • Analgesic nephropathy
  • Polycystic kidney disease
  • Hypokalaemic nephropathy
  • Renal lesions of sickle cell trait or disease
54
Q

neurogenic causes of UTI

A
  • Poliomyelitis
  • Tabes dorsalis
  • Diabetic nephropathy
  • Spinal cord injuries
55
Q
  • Further investigation of complicated UTI/recurrent UTI, UTI in men and children
A
  • Renal USS- see if there is a structural abnormality
    • Polycystic kidney disease
    • Nephrocalcinosis
    • Valves
    • Stenosis or bands
    • Calculi
    • Extrinsic ureteral compression

IV urography- this is often under guidance of urology

56
Q

when do you do urine culture and sensitivies in women with UTI

A

only given in recurrent UTIs for women

to check sensitivity of antibiotics just in case they have previously developed resistance in previous treatments for UTI

57
Q

why are nitrites specific to UTI and what can indicate if nitire negative but leucocyte positive

A
  • Nitrites are very specific because they are produced by E. coli
    • Nitrite-negative and leukocyte-positive may be a UTI caused by a non-coliform bacterium
58
Q

what agar is used for culturing in UTI and what do different organisms appear as

A

chromogenic agar - to see if growth is mixed or single

  • Pink= E. coli
  • Blue= Klebsiella, Enterobacter
  • Light turquoise= Enterococcus (gram positive organisms)
59
Q

what is worrying about candida. in urine + what should be done

A

Candida in the urine can also be a sign of candidaemia

candida has been seeded into the kidney

worrying in young children/ neonates

  • USS kidneys to see if there are any candida abscesses in the kidney
60
Q

complications of pyelonephritis

A
  • Perinephric abscess- may require drainage
  • Chronic pyelonephritis
    • Scarring
    • Chronic renal impairment
  • Septic shock (usually with Gram -ve bacteria)
  • Acute papillary necrosis

MICRO ADYA (22 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions