uti

urinary tract infections (UTIs) / cystitis

introduction

  • UTI's are common presentations, particularly in:
    • children with vesicoureteric reflux
    • women, especially post-coital
    • diabetics
    • following urethral instrumentation (eg. gynae surgery, IDC)
    • elderly men with prostatism (eg. benign prostatic hyperplasia (BPH)) and incomplete emptying of the bladder
    • patients with urologic abnormalities such as fistulae, neurogenic bladders, etc
    • patients with IDCs
  • UTI's are quite uncommon in men aged under 50 years
  • some patients have asymptomatic bacteriuria
  • most UTIs are caused by E.coli arising from contamination from faeces
    • E.coli accounts for > 80% of healthy premenopausal women with acute uncomplicated cystitis
      • other common organisms include Klebsiella pneumoniae, Enterobacter, enterococci and Gp B streptococci although it appears enterococci and Gp B streptococci are rare causes of cystitis in healthy women without E.coli also being involved 1)
  • a significant risk for women in particular, travelling to countries with high rates of multi-drug resistant faecal organisms such as India and other countries in Asia, is that they will return with these organisms and develop multi-resistant UTIs
    • multi-drug resistant E.coli (resistance to more than 3 groups of antibiotics):
      • Australia: 4.5% in 2008, 7.6% in 2012 and similar rates of E coli isolates resistant to fluoroquinolones
      • Mediterranean countries have 30-50% of E coli isolates resistant to fluoroquinolones
      • consider Rx with nitrofurantoin: 5 days for women (including pregnant women), 7 days for men
  • whilst most UTIs present with dysuria, urinary frequency, urinary urgency, and suprapubic tenderness, these are often absent and patients may present with acute pyelonephritis, unstable diabetes mellitus, urosepsis, delirium or unexplained falls
  • neonates with UTI's are at risk of developing gram negative meningitis, hence the usual Ix workup inclusion of lumbar puncture (LP) in these patients
  • occult acute pyelonephritis occurs in 15-50% of patients with UTI, particularly in older women

diagnosis

  • combination of dysuria, urinary frequency, and urinary urgency is ~75% predictive for UTI in men
  • women who have UTI symptoms probably do have a UTI - PCR detects E.coli or S. saprophyticus in 98% compared with only 11% of women without symptoms, while culture detects UTI in 80% if they have symptoms and 10% in those without symptoms according to a Belgian study in 2017 2)
  • diagnosis is suggested by finding large numbers of leukocytes +/- positive nitrites on a freshly collected urinalysis
    • other causes of leukocytes on urinalysis include:
    • a positive nitrite test is poorly sensitive but highly specific for UTI
  • diagnosis is confirmed by urine culture (preferably without contamination during collection)
    • this is particularly the case if a single organism is cultured that is known to be a uropathogen such as E.coli, K. pneumoniae or Staph. saprophyticus
    • it would appear that cultures from mid-stream samples in healthy women with cystitis showing enterococci or Gp B streptococci may not correlate with catheter sampled cultures raising doubts that these are the cause of the UTI - most of these cases also have E. coli (NEJM Nov 14 2013))
  • culture is very useful as it not only confirms diagnosis and thus assists in managing misdiagnosed cases, but it also is helpful in choice of antibiotic Rx for those not responding to Rx who may have drug resistant organisms causing the UTI.
  • patients who are already on antibiotics may give a false negative culture
  • cultures showing a sterile pyuria should be considered for other aetiologies if this is not explicable by prior antibiotic Rx

Rx of uncomplicated acute cystitis

  • exclude urosepsis, acute pyelonephritis and renal colic with obstructed ureter
    • NB. back pain with fever + UTI usually need iv antibiotics and admission
  • exclude other causes of complicated cases:
  • NB. asymptomatic bacteriuria is common in the elderly in residential care and should NOT be treated as risks generally outweigh benefits
    • incontinence, dysuria, and nocturia should not always be attributed to UTI
    • ensure clean urine sample such as:
      • in-out catheter for women
      • newly applied condom catheter for men
      • aspirate catheter port not the drainage bag in those with IDC in situ
    • Rx elderly with antibiotics if:
      • fever or delirium + a clinical symptom or sign of UTI
      • IDC + fever or delirium or flank tenderness or rigors
  • check pregnancy status (as trimethoprim is C/I and course of Rx may need to be longer if pregnant)
  • do not assume that a sexually active female with dysuria has a UTI without first excluding the possibility of sexually transmitted disease–related cervicitis, vaginitis, or pelvic inflammatory disease
  • if vomiting, unwell or febrile:
    • consider single dose of iv antibiotics such as ceftriaxone or perhaps gentamicin then either ongoing iv or oral antibiotics as indicated
  • if not vomiting and thus able to tolerate oral antibiotics, then Rx according to local known resistance patterns
    • in general, adult women antibiotic options include:
      • trimethoprim 300mg once daily 3 days (not if pregnant)
      • cephalexin 500mg bd 5 days
      • amoxycillin with clavulonic acid i bd 5 days
      • nitrofurantoin 100mg bd for 5 days (safe in pregnancy)
        • NB. avoid long term use as risk of peripheral neuropathy and pulmonary toxicity (esp. elderly patients)
      • NB. amoxycillin alone is only indicated if known sensitivity of organism
      • NB. avoid fluouroquinolones such as norfloxacin as 1st line Rx as they should be reserved for multi-resistant cases or Pseudomonas infections
    • consider adding urinary alkalisers such as Ural to reduce dysuria symptoms
  • if pregnant, repeat urine culture at least 48 hours after completion of treatment to confirm clearance of infection.
  • men should have 14 day course of the above antibiotics and follow up Ix to exclude an underlying urologic abnormality (renal USS +/- CT KUB)

complicated UTIs

inclusion criteria

Rx of UTI with IDC in situ

  • do not Rx just because cloudy, malodorous or pyuria
  • Rx if fever, flank pain, acute haematuria:
    • is there sepsis / septicaemia, if so Rx aggressively
    • if ongoing catheterisation required:
      • replace IDC BEFORE taking a urine culture (culture will be more reliable than if taken with old catheter) and starting Rx to reduce risk of superinfection with more resistant organisms
      • usual minimum Rx is 7 days, may need 10-14 days

prevention

  • women should completely empty their bladder immediately after sexual intercourse
  • those with recurrent UTI's should avoid use of IUCD and spermicides as these may increase risk
  • in postmenopausal women, the use of intravaginal oestrogen may reduce recurrent infections
  • cranberry products may reduce the incidence of symptomatic UTI in women (although evidence is poor), including in pregnancy, and of asymptomatic bacteriuria but are of limited utility during UTIs
  • avoid dehydration
  • avoid prolonged urinary or faecal contact (eg. elderly in residential care)
  • address constipation or fecal impaction
  • patients with recurrent UTI's may warrant prophylactic strategies
    • intermittent prophylaxis - antibiotic dose within 2 hours after sexual intercourse
    • Lactobacillus pessaries may reduce recurrence rates

podcasts and other resources

uti.txt · Last modified: 2017/05/01 13:07 by gary1