1
Q
are UTIs common or rare
A
- a very common disease
- 175 million cases per year worldwide
2
Q
what % of women will experience a UTI in their lifetime
A
40-50%
3
Q
what % of men will experience a UTI in their lifetime
A
10-12%
4
Q
what % of women will experience a second UTI in their lifetime
A
25%
5
Q
what % of women will experience a third UTI in their lifetime
A
3%
6
Q
what is the normal treatment for UTIs
A
antibiotics
7
Q
what are the downsides to treating a UTI with antibiotics
A
- costly
- disrupts normal flora
- promotes drug resistance
8
Q
what is a result of treating UTIs with antibiotics
A
- sterilisation of urine
- loss of symptoms
- pathogen is not eradicated!
9
Q
what are the key symptoms of UTIs
A
- frequent urination
- painful urination
- hesitancy before urinating
- urgency
10
Q
what are the symptoms of UTIs for someone with cystitis
A
- bad smell
- cloudy urine
- bloody urine
11
Q
what are the symptoms when UTIs reach the kidney
A
- flank (kidney) pain
- nausea
- fever
- vomiting
12
Q
what are the 2 ways UTIs can be acquired
A
- community acquired UTI
- hospital acquired UTI
13
Q
how are UTIs acquired from the community
A
- mainly young women
- caused by bacteria UPEC
14
Q
how are UTIs acquired from the hospital
A
- device related (catheter)
- caused by bacteria UPEC and other organisms
- greater risk of drug resistance
15
Q
how is a UTI collected
A
- a sample of urine is given from the patient
- the perineal area is cleaned before collecting the sample
- the urine is taken from the mid stream
- it is stored at 4°C if it can’t be tested immediately
16
Q
what kinds of urine analysis can you do with the urine sample in a clinical setting
A
dipstick test
- checking for presence of nitrites
- checking for presence of leukocyte esterase
- these positives indicate presence of infection
17
Q
what kinds of urine analysis can you do with the urine sample in a laboratory setting
A
- urine sediment microscopy
- gram staining and light microscopy
18
Q
describe urine sediment microscopy
A
- examining urine under a microscope to identify solid components
- looking for bacteria, white blood cells, and translational epithelial cells
19
Q
describe gram staining and light microscopy for urine analysis
A
- look for gram-negative rods
- look for presence of neutrophils
- these positives indicate presence of infection
20
Q
what is the major microbial cause of community acquired UTIs
A
Escherichia coli
21
Q
what is the major microbial cause of hospital acquired UTIs
A
- Escherichia coli
- enteric bacteria (klebsiella, enterobacter)
- proteus
22
Q
how do you identify which microbe the gram-negative rod from the urine sample is from
A
culture:
- CLED agar
- then enumeration
23
Q
how do you identify the microbe causing a UTI via CLED agar
A
- cysteine: UPEC strains require this to grow
- lactose: UPEC and kelbsiella ferment lactose from blue to yellow. pseudomonas and proteus don’t
- low levels of electrolyte: no swarming of proteus over the agar
24
Q
how do you identify the microbe causing a UTI via enumeration
A
- a measured amount of urine was added to the CLED agar
- count the colonies that grew on the agar
- use the number to estimate CFU/mL in the urine
25
what do different values of CLED agar --> enumeration tell you
>10⁵ CFU/mL = infection
<10⁴ CFU/mL = urethral or vaginal contamination
10⁴ to 10⁵ CFU/mL = evaluate with clinical information
26
how can we further identify the bacteria after CLED agar
- take yellow colonies (lactose fermentators)
- differentiate them using biochemical tests
- however this is an older method
27
what are the biochemical tests used to differentiate lactose fermenters from CLED agar
- indole
- methyl red
- VP
- citrate
28
what are the different results expected from biochemical tests used to differentiate lactose fermenters from CLED agar
- E. coli gives ++--
- enterobacter and Klebsiella give --++
29
what is a modern method for further identifying the bacteria after CLED agar
- MALDI-TOF (rapid identification)
1) take the sample for mass spectrometry analysis
2) the profile of molecular weights can be used to identify the bacteria
30
what is the source of E. coli for UTIs
faecal origin
31
why do community acquired UTIs mainly affect females
- since their urethra is shorter
- the vagina is in closer proximity to the anus (where E. coli resides in faeces)
32
how can men get community acquired UTIs
- older men are in risk of this
- stasis: the bladder doesn't fully empty so bacteria in the urine can remain and grow for longer in the bladder, leading to infection
33
how do hospital-acquired UTIs occur
- if an individual can't drain the bladder, they get a catheter
- the longer the catheter is left in, the greater the chance of infection occuring
34
what are the risk factors for UTIs
- sexually active women
- women with previous UTIs
- antibiotics or other treatments that disrupt normal vaginal flora
- urinary catheter
- underlying disease leading to stasis or prostatic hypertrophy in men
35
what are UPEC's virulence factors
- adhesins
- capsule
- flagellum
- O antigen
- K antigen
- iron chelators
- alpha-hemolysins
- cytotoxic necrotising factor
36
how are adhesins a virulence factor for UPEC
adhesins include pili or fimbriae that attach to and invade bladder epithelium
37
what helps E. coli to evade the immune system
- capsule
- O antigen
- K antigen
- flagellum
38
how does E. coli get its nutrients
- it gets iron via iron chelators
- these are enterobactin and yersiniabactin
- these can bind to iron containing compounds like hemoglobin
39
what does alpha-hemolysins do for E. coli
- virulence factor
- at low concentrations it causes inflammation
- lyses RBCs and WBCs
40
what does cytotoxic necrotising factor do for E. coli
- virulence factor
- causes inflammation
- damages tissue, releasing nutrients for the bacteria
41
what is the most important pillus for E. coli
- type 1 (fim) pili
- produced by all enterobacteriaceae
- bind to mannose residues in glycoproteins present on surface of bladder
- this ensures that when we urine, the bacteria stay stuck to the bladder
42
what's a pilus other than type 1 that enterobacteriaceae bind
- some strains possess P-pili
- bind to a molecule called globobiose
- this is important for colonisation of the kidney
43
what is the typical route of a UTI
- ascending infection
- cystitis → bladder → ureter → kidney → bloodstream
- sometimes, bacteria in the blood can infect kidney instead of the other way around
44
what are the treatment options for a patient with recurrent cystitis
- take fluids
- pain relief
- hygiene
- don't hold urine
45
what foods can offer treatment for a patient with recurrent cystitis
- cranberry juice
- mannose tablets
- live yoghurt
- however clinical research hasn't show much significant effects with these foods
46
does a patient with recurrent cystitis need antibiotics
- reduce the use to combat resistance
- if patient is young and healthy, fluids and immune system can be enough to clear the infection
- if symptoms persist or get worse, then a revisit to the doctor is recommended
- if enumeration shows there is significant UPEC bacteria, then antibiotics may be recommended
47
what are things to consider when choosing an antibiotic for a patient to treat recurring cystitis
- be aware of resistance issues (nothing abnormal in the community)
- be aware of persistent infections
48
what are the antibiotic options for a patient to treat recurring cystitis
- option A: amoxil, since it cleared it previously
- option B: not amoxil, since the infection ended up coming back
49
what are the reasons for choosing amoxil to treat a patient with recurring cystitis
- the patient is in discomfort
- the patient is at risk of a more serious infection
- the antibiotic has worked before
- the patient wants it
- however the recurrence of the infection could be due to resistance developed to amoxil
50
what should antibiotic should you treat a patient with recurring cystitis with if not amoxil
- use a non-penicillin antibiotic (since amoxil is a penicillin antibiotic)
- trimethoprim: inhbits folic acid synthesis and therefore DNA synthesis
- ciproflaxacin: directly inhibits DNA synthesis
medsci 202
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