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
a US 2025 study suggested that 18% of UTI's are due to the same E.coli strain contaminating meat (esp. poultry) and that lower socioeconomic areas, women and older men were most at risk1)
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 2)
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
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
the intracellular Acinetobacter baumannii organism may remain in bladder epithelial cells forming a reservoir and cause infection with 24hrs of a urinary catheter being inserted according to a study in mice in 2022 3)
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 4)
diagnosis is suggested by finding large numbers of leukocytes +/- positive nitrites on a freshly collected urinalysis
other causes of leukocytes on urinalysis include:
contamination during collection
urine sample at room temperature for prolonged period
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
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
preferred antibiotic if sepsis in 2022 is IV ceftazidime as it also covers Pseudomonas and is less toxic than gentamicin
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