UTI's Flashcards
What is asymptomatic bacteriuria?
asymptomatic - no symptoms
bacteriuria - presence of bacteria in urine
Why is there bacteria in the urine even without UTI?
urine passes through non-sterile skin e.g. urethra
How much bacteria is normal to have in the urine?
- less than 10 (to power 5) bacteria/ml of urine
- based on mid stream sample only
What is the ideal urine sample?
Mid stream sample
i. e. don’t catch urine at start and end of urination
- not always possible
Is urine in the body sterile?
Yes - filtrate of the blood
and blood is sterile
What does sterile mean?
complete absence of micro-organisms including viruses and bacteria
Why does bacteria needed to be sent to the lab fast?
Bacteria which may be normal can replicate in sample
What are the classic triad of symptoms for UTI?
- frequent urination
- urgent urination
- dysuria (pain when urinating)
Who is more likely to have asymptomatic bacteriuria?
Older people - don't necessarily have infection - just have more bacteria in urine Pregnant women - can have asymptomatic infection
How is a UTI tested for?
need to find the organism
- sample from inflamed organs i.e. urine in UTI
- blood sample if sepsis suspected
- take sample before antibiotics (stop bacteria from being killed off before so can diagnose)
- can also use dipstick if simple UTI with definitive result don’t need lab
What does uncomplicated infection mean?
infection where:
- treatment is likely to be successful
- Symptoms are obvious e.g. classic triad
Which UTIs are uncomplicated?
Lower UTI
- Urethritis
- Cystitis
What bacteria are likely to cause the uncomplicated UTIs?
E.coli
What antibiotics are used in lower urinary tract infections?
Nitrofurantoin
Trimethoprim
Why do UTI treatments fail?
Impeded flow:
- old age (prostates can impede flow)
- pregnant (uterus can impede flow)
- kidney stones
- plastic in urinary tract
- resistance bacteria (often from previous antibiotic)
What are symptoms of UTI’s outside of classic triad?
- loin pain
- fever
both need to be treated
What needs to be treated with UTI outside infection?
- Symptoms e.g. loin pain + fever
- underlying conditions e.g. stones
What treatments are used in complicated UTI’s?
Antibiotics:
- Co-amoxiclav
- Gentaminin (can be nephrotoxic so contraindicated in renal failure patients)
How is treatment in pregnant women with UTI different?
- Don’t need to show symptoms to get antibiotic treatment
- As good evidence that treatment will reduce upper urinary tract infection (and so chance of pyelonephritis) which decreases chance of early labour and underweight babies
What antibiotic shouldn’t be given to pregnant women?
Trimethoprim as folate antagonist, lack of folate can cause spina bifida in child
What antibiotics can be given to pregnant women?
Nitrofurantoin
Amoxicillin
Cefalexin
What are the challenges of UTI in older age?
- more likely to have co-existing conditions e.g. diabetes
- greater chance of asymptomatic bacteriuria
- higher chance of PVR
- Catheters used often and higher chance of infection
- more vulnerable to C difficile when exposed to antibiotics
- Less able to get MSU sample so more likely to be pos for bacteriuria
What is pyelonephritis?
- infection of the kidney
- which leads to scarring of tissue which can lead to renal failure and hypertension
- can develop as a result of UTIs
How are pregnant women and young children checked for UTI’s?
- Dipstick test
- if leukocytes, proteins or nitrates present then sample sent to lab
What are the challenges of UTI’s in children?
- Less likely to spot symptoms
- Risk of renal scarring
- recurrent infection increases risk of renal failure later in life
- harder to get MSU sample so more likely to test pos for bacteriuria
What symptoms can be looked for in older adults and children with UTI’s?
- distress
- fever
- confusion
- agitation
What can a dipstick test for specific to UTI’s?
- Leukocyte esterase
- Nitrates
- proteins
Are dipsticks sensitive or specific?
High sensitivity so high negative predictive value i.e. if test result is negative the diagnosis of UTI very unlikely
What antibiotics can be given to children while waiting for bacterial culture?
- cephalosporin cefalexin
- co-amoxiclav
What is PVR?
post voiding residual volume i.e. urine left in bladder after urination (higher in older people) which increases risk of infection
What is a common reason for recurrent UTI’s in older men?
- Bacterial prostatitis (infection of prostate tissue) which is:
- usually caused by recurrent UTI’s
- can also be caused by STIs: Neisseria, gonorrhoea and chlamydia
- and cystoscopy of urethra
What symptoms may point towards bacterial prostatitis?
- Rectal pain
- ejaculatory pain
- urinary retention
- prostate swelling
How is bacterial prostatitis tested for and treated?
- Urine and blood sample sent to lab
- fluoroquinolone drugs usually ciprofloxacin, only used in bacterial prostatitis as serious side effects but needed as good activity against gram negative species and reach therapeutic target in prostate tissue
What is the protocol with infection when using catheter?
- remove catheter first and if need to replace with new one may have to go on antibiotics
- often bacteria have colonised by not yet an infection so bacteriuria but don’t need antibiotics
- however colonisation can then lead to infection
What organisms usually cause Catheter infection?
gram positive or candida ( fungi)
What is biofilm?
- organised community of bacteria existing in a resilient multicellular system to maintain themselves
- can exist on organic or non-organic surfaces
How are biofilms dealt with?
Remove surface biofilm existing on as resilient to antibiotics
What makes biofilms so good at surviving?
- secrete polysaccharide matrix to suspend them
- bacteria near foreign surface secrete adherence molecules
- other bacteria express antibiotic resistant mechanisms
