Urinary tract infection (UTI) Flashcards
what is UTI
urinary tract infection
presents as cystitis - inflammation of the urinary bladder or part of the urinary system
classifying UTI
lower UTI - bladder (cystitis), urethra (urethritis) + prostate in men (prostatitis)
upper UTI - ureters, kidney
= pyelonephritis
peak incidence in
women
due to a shorter urethra and proximity to the anal region
age
generally UTIs increase with age
so generally more common in women, then elderly men
what type of UTI do M/F more commonly get
Males - mostly urethritis or prostatitis (lower UTI)
Females - mostly cystitis (bladder) or pyelonephritis (upper UTI)
uncomplicated UTI
only in women
UTI in immunocompetent, premenopausal, non-pregnant women
complicated UTI
if the pt (can be M/F)
- is a child
- is pregnant
- has a structural/functional UT abnormality and obstruction of urine flow
- has a comorbidity that increases risk of acquiring infection or resistance to treatment, eg. poorly controlled diabetes, CKD, or immunocompromised
- has recent surgery of the UT
aetiology of UTI
infection caused by bacteria from pts own bowel flora
bacteria ascends along the urethra to the bladder for lower UTI for pyelonephritis ascends the ureters to the kidney
how else can upper lower become upper UTI
bacteria can reach the kidney via the bloodstream
occur in infective endocarditis pts
what type of bacteria commonly causes UTI
most caused by E.coli (gram -ve)
is UTI usually community or hospital acquired
CAI - E.coli, staph.sapro
HAI - E.coli, Klebsiella, Enterobacter staph.aureus (gram +ve)
risk factors
- female gender (due to shorter urethra and closer proximity to anal region)
- new sexual activity (esp young women)
- pregnancy - hormonal changes cause urinary stasis and vesicoureteral reflux, increasing UTI risk
- postmenopause -** reduced oestrogen**, less vaginal lactobacilli so increases vaginal pH and increases colonisation by E.coli
- indwelling catheter - CAUTI
- structural/functional abnormalities of the UT - UT stones, UT stasis (incomplete bladder emptying)
- prev conditions eg. UTI, DM, renal surgery, immunosuppression
- taking abx or using spermicide-coated condoms - alters vaginal flora so E.coli overgrows
cardinal symptoms of UTI
dysuria
urgency
frequency
symptoms of upper UTI (pyelonephritis)
kidneys and ureter
- flank pain
- fever, chills, night sweats, rigors
- nausea + vomiting
signs of upper UTI
- costovertebral angle (back) tenderness,
felt as pain when percussing the back
symptoms of lower UTI (bladder, urethra)
- increased frequency
- dysuria (painful, burning on weeing)
- haematuria
- cloudy, smelly urine
- discharge (urethritis, more likely for STIs)
signs of lower UTI
-suprapubic pain and tenderness,
felt as pelvic pain/pressure
easy way to differ between upper and lower UTI
fever often absent in lower UTIs
so fever/chills + flank pain is definitely more likely an upper UTI (pyelonephritis)
UTI can also be asymptomatic esp in
immunocompromised pt - no frequency or dysuria, just abdo pain, fever, haematuria
elderly pt - new confusion
young children - atypical symptoms, UTI often caused by chronic constipation
signs of atypical infection in children
- seriously ill
- poor urine flow
- abdominal or bladder mass
- raised creatinine
- septicaemia
- failure to respond to treatment with suitable antibiotics within 48 hours
- infection with non-E. coli organisms
asymptomatic bacteriuria
common in the elderly
when a urine culture can confirm presence of UTI but no signs/symptoms
treating bacteriuria
not treated as it leads to resistance
but 3 certain pt groups are treated:
- pregnant women
- pt with renal transplant
- pt undergoing genitourinary tract procedures
pregnant women are at risk of complicated UTIs - esp. pyelonephritis
what does this cause
- low birth-weight baby
- premature baby
so treat urgently
diagnosing UTI
uncomplicated (pt doesn’t need UT abnormalities or co-morbidities) can be purely based on clinical history - present with dysuria, frequency or urgency - along with an absence of vaginal discharge
or URINE CULTURE of clean-catch midstream specimen of urine
results for diagnosing bacteriuria
- gram -ve pathogens reduce nitrates to nitrites, so produces a red colour in the reagent square
- pyuria is increased WBC in the urine so leucocytes (WBC in urine) release esterases
SO dipsticks that are positive for both nitrite and leucocyte esterase are highly predictive of acute infection
investigating UTI
urine sample must be CLEAN-CATCH MIDSTREAM SAMPLE (first-catch has contamination with vaginal/skin flora)
urine dipstick analysis
- cloudy urine due to WBC present
- +ve nitrites or leukocytes due to bacterial infection
don’t use urine dipstick testing for diagnosing UTI in
elderly or pt with indwelling urinary catheters
urine culture can be done if pt is
- pregnant
- elderly
- have visible/invisible haematuria
- recurrent UTI/treatment not working
- risk factors for complicated UTI
so to investigate
always take a midstream sample
but depends if do either urine dipstick for urinalysis or urine culture for microscopy
difference between dipstick vs culture
- dipstick only picks up UTI if pt has pyuria (WBC in urine) but not all child pts have
so only using dipstick is usually inadequate for diagnosis, esp urine culture for children (eg. of complicated UTI), or pregnant women (asymptomatic bacteriuria)
dipstick better for woman with uncomplicated UTI
other radiological investigations
- ultrasound to rule out urinary obstruction or renal stones in acute uncomplicated pyelonephritis
- static radioisotope scan (e.g DMSA) to identify renal scars, sign of damaged kidneys, done 4-6months after initial infection
- micturating cystourethrography (MCUG) to identify vesicoureteric reflux, for babies <6months with recurrent, atypical infections
NICE guidelines for imaging the urinary tract
- babies <6months with first UTI which responds to treatment should have an ultrasound within 6 weeks
- children >6months with first UTI which responds to treatment don’t need imaging unless features suggest atypical,recurrent infections
differential diagnosis of UTI
if symptoms persist, but urine dipstick is negative and even urine culture comes back negative !!
- abacteriuric frequency or dysuria (urethral syndrome) : caused by bladder trauma after intercourse, vaginitis, urethritis in the elderly, chlamydia and TB in young women with pyuria
- interstitial cystitis : women >40yo have frequency, dysuria, severe suprapubic pain, inflammatory changes with ulceration of the bladder base shown on cytoscopy
- irritable bladder : occurs after previous UTI, predominant frequency and passing smaller volumes of urine
acute vs chronic pyelonephritis
acute:
- fever
- loin pain
- bacteriuria
- pus in renal medulla and cortices
- leucocyte infiltration in renal tubules
chronic: reflux nephropathy
- vesicoureteric reflux : VUJ is usually a one way valve where urine enters the bladder from above, and then ureter shuts when bladder contracts to prevent reflux of urine, but incompetent valve means during bladder voiding, infected urine jets up the ureter, causing incomplete bladder emptying and later kidney damage - this reflux stops near puberty so for younger children with recurrent UTI, can re-implant competent ureteral valve or give antibiotic prophylaxis to reduce kidney damage, this can reduce risk of UTI but increases risk of developing antimicrobial-resistant bacterial strains
managing UTI - non pharm
educating women on risk factors for UTI:
- using spermicide
- frequent sex
- new sexual partner
increase fluid intake
personal hygiene (don’t delay urination, don’t use vaginal douche, don’t wipe from front to back after poo)
main pharmacological treatment for acute pyelonephritis is
oral antibiotics - started after urine cultures are taken
other treatments maybe IV fluids, analgesia, antiemetics
oral abx manage UTI in the community, hospital admission is only needed if
- pregnant woman
- pt not improving 48hrs since treatment started
- severe pain
- pt with severe features : tachycardia, tachypnoea, hypotension, reduced urine output, confusion
- pt who can’t tolerate oral medicine/fluid
- pt at risk of complications eg. elderly pts, DM pts, pts with GUT abnormality and babies <3months
managing upper UTI (pyelonephritis)
men + non-pregnant women
- cefalexin for 7-10 days (broad spectrum)
- co-amoxiclav or trimethoprim
pregnant women
- cefalexin for 7-10 days
- cefuroxime given IV if can’t take orally or vomiting
uncomplicated
- oral ciprofloxacin for 7-10 days
- alternatives are co-amoxiclav or cefalexin
pt with catheters
- remove catheter if possible
- ensure catheters are correctly positioned, still draining, not blocked
- change catheters if long term catheter in place for >7days
MAINLY : give broad spectrum cephalosporin or quinolone for men + non pregnant women for 10-14 days
managing lower UTI
non pregnant women
- trimethoprim/nitrofurantoin for 3 days
- only send a urine culture if >65yo or visible/invisible haematuria
(only preg women NEED their urine cultured as can have asymptomatic bacteriuria, which is usually harmless for non preg women)
SYMPTOMATIC pregnant women
- always send a urine culture
- nitrofurantoin for 7 days (avoid if near term)
- second line is amoxicillin or cefalexin for 7 days
- trimethoprim is teratogenic in the first trimester so avoid in pregnancy!
ASYMPTOMATIC BACTERIURIA pregnant women
- urine culture should be done at first antenatal visit
- nitrofurantoin for 7 days (avoid if near term) or amoxicillin/cefalexin for 7 days
- still treat otherwise can progress to acute pyelonephritis!!
- further urine culture once treated with abx to see if cured
men
- always send a urine culture before starting abx
- trimethoprim/nitrofurantoin for 7 days
- trimethoprim for 4-6 weeks if prostatitis is suspected as can penetrate the prostate
- don’t need urology referral
CAUTI pt
- don’t treat if asymptomatic
- 7 day course of abx if symptomatic and change catheter if in for >7days
complications of UTI
- lower UTIs can ascend and cause upper UTIs (pyelonephritis), renal abscess, impaired renal function, renal failure, urosepsis
- UTI in pregnant women can cause premature delivery and low birthweight, so always treat even asymptomatic bacteriuria and abx must be given for 7 days (not 3 !)
- sepsis maybe if pre-existing catheter
