Primary Care - UTIs Flashcards
What abbreviation is used to remember the different stages that must be covered when contacting microbiology?
HD - MAP
- H - history
- D - diagnosis
- M - microbiology results
- A - antibiotic plan
- P - plan (non-antibiotic)
What can it mean if epithelial cells are present in a urine culture?
- epithelial cells are skin or vaginal cells
- this means that a MSU sample has been contaminated by skin or perineal flora
What diagnosis would be made here and why?
Would you want any further investigations?
asymptomatic bacteruria
- this is NOT a UTI as the patient is asymptomatic
- you would not want to do any further investigations or start antibiotics as this patient is not high risk
In this case, where should the MSU been sent to instead of microbiology?
- the patient had no symptoms and there was no indication to screen for asymptomatic bacteruria
- the MSU should not have been sent to microbiology
- it should have been sent to biochemistry to look for microalbuminaemia
- this is a marker of diabetic nephropathy
What is the definition of asymptomatic bacteruria?
What are the 3 main risk factors?
it is the presence of bacteria in the urine of an asymptomatic patient
Risk Factors:
- increasing age
- women who are sexually active
- diabetes
What organisms cause asymptomatic bacteruria?
the bacteria isolated are similar to those causing UTIs, which are gut bacteria
- E. coli
- Klebsiella
- Proteus
- Enterobacter
Who needs to be screened and treated for asymptomatic bacteruria and why?
patients who can develop complications from asymptomatic bacteruria:
-
pregnant women
- associated with a higher rate of pyelonephritis
-
those undergoing urological procedures
- if there are bacteria in the urinary tract, manipulation of the urinary tract can lead to infection / bacteraemia
-
post-renal transplant
- may negatively affect the transplant
Why is screening for asymptomatic bacteruria not recommended?
most patients have no adverse consequences and derive no benefit from antibiotic therapy
What is the difference between colonisation and infection?
Colonisation:
- the presence of bacteria on body sites that are exposed to the environment which do not cause infection
Infection:
- presence of micro-organisms causing damage to body tissues
- this usually occurs in the presence of acute inflammation
How can you tell the difference between a UTI and asymptomatic bacteruria?
What is the difference in management?
- you cannot tell the difference from an MSU result as they both show growth of bacteria
- you can only tell the difference clinically and if the patient has symptoms or not
- colonisation (AB) does not require treatment, whereas infection (UTI) needs antibiotic treatment
In young women presenting with urinary frequency and dysuria when is an MSU sent?
- usually in young women with lower UTI symptoms, an MSU is only sent when there is failure to respond to initial treatment
What is the diagnosis?
Why?
pyelonephritis (upper UTI)
- there are symptoms of lower UTI - dysuria, frequency & urgency
- but also the presence of fever and LOIN PAIN
- fever can present in lower UTI, but it tends to not be as persistent
Which organisms typically cause pyelonephritis (upper UTI)?
Gram negative organisms:
- most commonly enterobacteriaceae (gut bacteria)
- E. coli
- Proteus
- Klebsiella
- Pseudomonas aeurguinosa if there is an abnormal renal tract or catheter
Gram positive organisms:
- very rarely S. aureus - which can cause a renal abscess in IVDUs
How would you investigate upper UTI?
- urine dip (unless catheter in situ)
- MSU / CSU before starting / changing antibiotics
- blood cultures (if systemically unwell)
- renal ultrasound (if patient is in hospital)
Which antibiotics would you use to initially treat an upper UTI?
- start with broad spectrum antibiotics that will cover enterobacterciae
- make sure the patient is not allergic
- if the patient is not systemically unwell, they can have PO antibiotics
- this is usually ciprofloxacin or co-amoxiclav
Which 3 antibiotics cannot be used to treat upper UTI and why?
- nitrofurantoin
- pivmecillinam
- fosfomycin
- these are not active against upper UTIs as they do not penetrate the kidney parenchyma sufficiently
- they are active in lower UTIs as they are concentrated in the urine
How should the antibiotic being used to treat an upper UTI be changed after time?
When should this occur?
- antibiotic choice should be reviewed at 48-72 hours with patient response and microbiology results
- need to ensure antibiotics are effective against the identified infection
- want to choose a more narrow-spectrum antibiotic to reduce the incidence of side effects
What does ESBL stand for?
What does it mean if a culture is ESBL positive?
extended spectrum beta lactamase
- ESBL positive culture means there are bacteria present that produce ESBLs
- these are enzymes that break down beta-lactam antibiotics, making the bacteria multi-drug resistant
What would the diagnosis be in this scenario?
Why?
Catheter associated UTI (CAUTI)
- symptoms of a UTI (fever, suprapubic tenderness, etc.) with the presence of a catheter
- if the patient has loin pain or extremely severe symptoms, this should be treated as an upper UTI and not CAUTI
Why does a CAUTI occur?
Why is it a clinical diagnosis?
- diagnosis is clinical and not microbiological as nearly all CSUs will grow bacteria due to colonisation of the catheter
- all CSUs have raised WCC as as soon as you insert the catheter, it irritates the bladder and causes an inflammatory response
- the presence of plastic allows it to become colonised by bacteria, leading to positive culture
If CAUTI is suspected, what is the next course of action?
a CSU should be sent to guide antibiotic choice
do NOT dipstick on a catheter sample as this will always be positive
What 3 reasons might there be for someone not responding to antibiotic treatment?
Poor source control:
- if you don’t get rid of the source of infection, the patient is unlikely to improve
- e.g. changing a urinary catheter
Wrong antibiotic:
- wrong empiric antibiotic
-
wrong dose
- ensure correct dose for patient age, weight, diagnosis and renal function
-
wrong route of administration
- antibiotics should be given IV if the patient is septic or treating a deep-seated infection
-
inadequate duration of therapy
- most infections take 24-48 hours to respond to antibiotic therapy
Antimicrobial resistance:
- if the patient has an ESBL positive (multi-drug resistant) organism
How should source control be tackled in a CAUTI?
catheter change under antibiotic cover
- catheter should be removed if no longer indicated
- it should be changed under antibiotic cover if needed
- it can be changed immediately if the patient is on regular IV antibiotics to cover the urinary tract
- or after 48 hours of suitable PO antibiotics
- or within 1 hour of giving a STAT dose of prophylactic gentamicin
What is important to consider if a patient has an ESBL positive culture and they are in hospital?
- as ESBLs are capable of breaking down most beta-lactam antibiotics, this makes the organism multi-drug resistant
- ESBLs are carried on plasmids which can spread from one bacteria to another
- this means they are an infection control hazard and the patient needs to be source isolated
