Lecture 32: Urinary Tract Infection Flashcards
what are the 2 key pathogens involved in UTI
- E coli
- proteus
what family does E coli belong to
enterobacteriaceae –> found in the gut
what is bacteriuria
presence of bacteria in the urine
what does asymptomatic bacteriuria mean
presence of significant amounts of bacteria in the urine w/o symptoms of UTI
what would be considered significant bacteria in the urine
> 100,000 bacteria/ml of urine
what is an important factor about the urine sample to be collected
must be mid stream urine sample
what measurement of bacteriuria would be considered unlikely to be significant
< 1000 bacteria/ml or urine
what body sites and fluids are considered sterile
- blood
- cerebrospinal fluid
- joint fluid
- most body tissues beneath epi
what body sites/ fluids are considered non sterile
any site/fluid/tissue assc. w/ a mucosal surface that communicates w/ outside environment
e.g. skin, GIT., upper resp tract
why do non-sterile samples need to be brought to the lab quickly
bacteria in the sample will be replicating during transit so any delay means the sample won’t be representative of bacteria inside Px
what is the classic triad of UTI symptoms
- frequency
- urgency
- dysuria
what examples of people can develop asymptomatic bacteriuria
- elderly
- pregnant women
- those with neurological impairment that prevents them sensing or expressing symptoms
what are other symptoms to look for in catheter Px w/ UTI other than triad
- confusion
- smelly urine
- fever
what group of people are an exception to the rule about only treating people w/ symptoms
pregnant women
what are the basic principles of diagnosing infection
- take sample from inflamed organ site e.g. urine
- take blood also if sepsis suspected
- ## take samples (bacterial culture) before giving antibiotics
who can be treated for UTI w/o sample of urine being sent for culture and why
- women if their symptoms are convincing and a bedside test (urine dipstick) is suggestive of infection
why
- in some non hospital settings e.g. GP almost certainly a delay in getting samples to labs
what is cystitis
inflammation of the bladder
differentiate complicated and uncomplicated cystitis
uncomplicated:
- lower UTI either in men or non-pregnant women who are healthy
complicated:
- assc. w/ risk factors that ^ risk of infection or risk of failing antibiotic therapy
what are the standard antibiotic drug choices and what is their bacterial target
and what other choices are there
standard:
- trimethoprim
- nitrofurantoin
target:
- E coli
other:
- fosfomycin
- pivmecillinam
what reasons might cause UTI treatment to fail
- anatomy or functional problems
- impeded flow
- old age and prostates
- pregnant uterus
- stones
- plastic in urinary tract
- resistant bacteria
name a complication that can arise from complicated UTI
pyelonephritis (kidney infection)
give the symptoms of pyelonephritis
- UTI triad
- loin pain
- fever
give drug options for treating pyelonephritis
- co-amoxiclav
- gentamicin
use therapeutic drug monitoring (TDM) as gentamicin can be nephrotoxic
what is therapeutic drug monitoring
measuring the actual concentration of drug in Px blood to ensure not causing harm
what are the risks for pregnant woman w/ UTI
pregnant uterus means that obstruction of urine is more likely so pregnant women w/ significant bacteriuria w/ or w/o symptoms have 30% estimated risk of developing upper UTI incl. pyelonephritis
outline the treatment for asymptomatic bacteriuria in pregnancy
- start w/ dipstick: leukocyte-esterase +/- nitrates
- MSU
- give nitrofurantoin, cefalexin (guided by cultures)
- repeat later in pregnancy
what drug should be avoided in treatment of asymptomatic bacteriuria in pregnant women
trimethoprim
what is a risk for children w/ UTI
renal scarring
what is a common predisposing factor for children for renal failure later in life
recurrent UTI in childhood
what symptoms of UTI are looked for in children or elderly w/ cognitive impairment
atypical symptoms
- distress
- fever
- poor feeding in infant
- worsening confusion
- agitation
in children what symptoms may localise to the urinary tract
- abdominal pain
- loin pain
- changes in continence
- triad
what is used as primary screening for UTI in children
dipstick test
is dipstick test a sensitive test or specific test
sensitive test (highly)
what is the difference between a sensitive and specific test
sensitive:
- high -ve predictive value –> -ve test = no disease
specific:
- high +ve predictive value –> +ve test = disease
what Rx is given empirically to children w/ UTI
- cephalosporin cefalexin
- co-amoxiclav
list some of the common challenges of UTI in old age
- co-existing conditions that lead to cognitive or physical disability –> ^ chance of unnecessary Rx
- ^ post void residual volume (esp ^ in prostate obstruction) –> more infections
- catheters
- greater vulnerability to C diff when exposed to antibiotics
- delirium secondary to UTI exacerbates dementia
- institutional living and hospitalisation –> ^ exposure to medical interventions and antibiotic resistant organisms
what is a common reason for recurrent UTI in older men
bacterial prostatitis
what risk factors are there for bacterial prostatitis
- older men
- younger men more sexually active –> STIs
- if man has undergone instrumentation of urethra (post procedure)
give some symptoms of prostate infection
- perineal or rectal pain
- ejaculatory pain
- urinary retention
- prostate swelling or tenderness
how is bacterial prostatitis diagnosis facilitated
urine samples and blood culture
what is the treatment for bacterial prostatitis and what are the assc. issues
- fluoroquinolone drugs e.g. ciprofloxacin
- serious side effects
- can drive antibiotic resistance and C diff infection
what is the first line Rx for catheter assc. UTI and why
- catheter removal
- catheter is a foreign body which can become colonised w/ bacteria
- biofilm can be present on the surface of colonised medicinal plastic
what is biofilm
collaborative multicellular community of bacteria
what is the issue w/ biofilm
very difficult (almost impossible) to remove physically and so is a common cause of recurrent infection - generally impermeable to antibiotics and resistant to host immune responses
