Microbiology Flashcards
What is an UTI
The presence of micro-organisms in the urinary tract that are causing clinical infection
MUST have symptoms
What is the definition of a lower UTI
Infection confined to the bladder
Also involves cystitis - bladder inflammation
What is the definition of an upper UTI
Infection involving the ureters +/- the kidneys
Also called pyelonephritis (in kidney)
Urine in the bladder is normally sterile - true or false
True
What is a bacteriuria
Bacteria present in the urine
Doesn’t always mean there is symptoms
List risk factors for UTI
Being female - shorter urethra
Catheterisation
Abnormalities of the urinary tract
How do bacteria get to the urinary tract
Ascending infection - common
The bacteria travel from the rectum or perineal skin up into the tract
Rarely bacteria from the bloodstream can seed in the kidneys
What is the best type of urine sample
Mid stream urine sample
First urine passed into toilet, without interruption collect next part in a bowl, finish in toilet
Transfer from bowl to container
Are urine dipsticks useful for UTI
They are in young patients
Look for nitrites and leukocytes
May see protein or blood
NEVER use in elderly or catheters
What are the main causative organisms of UTI
Gram –v bacilli are the biggest cause
E.coli in particular
Klebseilla, Enterobacter etc
Pseudomonas
What does a proteus UTI cause
Struvite stones - large ones that take shape of calyx (look like antlers)
Creates them by breaking down urea to ammonia - causes precipitation of salts
How does proteus appear when plated
Foul smelling - burnt chocolate
Looks like tree rings - swarming
What is a pseudomonas UTI associated with
Catheters and instrumentation
How do you treat a pseudomonas infection
Ciprofloxacin is the only oral one that works
Which gram positives can cause UTI
Enterococcus - from GI, common in hospital
Staph saprophyticus
Aureus rarely from bacteraemia
What are the symptoms of UTI
Dysuria
Increased frequency
Nocturia
Haematuria
If upper tract involved - fever, loin pain, rigors
Describe the different types of urine container
Sterile universal container - white lid, must reach lab within 2 hours
Boricon container - red lid, contains boric acid to stop bacteria multiplying, works for 24hrs
What is considered a significant result on urine culture
More than 10 to the 5 organisms per ml
Probably a UTI
Which antibiotic is used for uncomplicated lower UTI
1st line - Nitrofurantoin
2nd line - Trimethoprim
3 days in women and 7 days in men
If you get pus cells in a urine sample but no significant bacteria on culture, what could be the cause
Could be early phase of UTI
Honeymoon cystitis - urethral trauma
May be an STI
Abacterial cystitis
How do you treat abacterial cystitis
Alkalinising the urine may help (symptomatic relief)
What is an asymptomatic bacteruria and how would you manage it
Significant bacteriuria (>105 orgs/mL)
Patient is asymptomatic (incidental finding)
No pus cells in urine
DO NOT give antibiotics
How does treatment for asymptomatic bacteruria differ in pregnancy
You would treat with antibiotics
All women are screened at 1st antenatal visit
Can lead to pyelonephritis or IUGR or premature labour
When would you treat a catheter patient with a bacteriuria
ONLY if they have symptoms
Catheter samples will always grow bacteria
How do you treat complicated UTI or pyelonephritis in the community
Co-amoxiclav or co-trimoxazole (14 days)
How do you treat complicated UTI or pyelonephritis in hospital
Amoxicillin and gentamicin IV for 3 days
How do you give gentamicin
7mg/kg - refer to guidance
NOT in pregnancy
Take bloods 6-14 hours later to check it has cleared from system
Only prescribe for 3 days
If bacteria produced ESBL, how does it affect treatment
It will be resistant to all cephalosporins and almost all penicillin
May use nitrofuratinin, meropenem etc
Is trimethoprim safe in pregnancy
Yes but not in the 1st trimester
