25 year old, Loretta Willis presents to your general practice. She has had 2 days of stinging and burning when passing urine. She has tried the Ural recommended by her local pharmacist, but her symptoms have not resolved. She is concerned that she has another urinary tract infection.
Further history would involve the presence of previous infections - her age at onset, the frequency and severity. Have the previous UTIs been confirmed to exclude other possibilities such as trigonitis or interstitial cystitis, has she had any imaging to exclude a predisposing cause and any renal involvement? Has she had any recent diarrhoea or does she have chronic diarrhoea? If she has been prescribed antibiotics in the past has she been compliant and taken the full course to prevent the risk of developing resistance? Has she had any adverse reactions to previous treatment? Is she aware of the appropriate precautions with adequate daily fluid intake, hygiene, pre- and post-coital voiding and does she adhere to these recommendations? Is there a history of other infections to suggest an underlying immune deficiency and has she had any other blood tests in this regard? Does she have any children and if so were there any problems with the delivery e.g. forceps rotation with possible effect on the bladder, is there any stress or urge incontinence and has she been shown pelvic floor exercises?
UTI can be strongly suspected on the basis of the patient's symptoms. These include:
Clinical examination may reveal fever, rigors, lower abdominal discomfort and loin pain when the renal angle is balloted posteriorly. The latter findings are more suggestive of complicated UTI or pyelonephritis.
In males, phimosis (inability to retract a tight foreskin over the glans) or prostatomegaly and in females, vaginal prolapse may be evident to explain the UTI. Urinalysis looking for the presence of blood, white blood cells (neutrophils), nitrites, protein, glucose.
Symptoms may vary in different age groups e.g. infants and young children may present with fever of otherwise unknown origin, signs of feeding difficulties, lassitude, frequent and offensive urine or cloudy urine noted by parents, vomiting and apparent abdominal pain. In the elderly symptoms may include mental changes or confusion, nausea or vomiting, abdominal pain. Prevalence of asymptomatic bacteriuria rises with age (in institutional care it rises to ≈ 40% in women and 30% in men).
In women, recurrent infections are common and further investigation is only justified if infections are frequent (three or more per year) or unusually severe. Men and children with recurrent infections, and patients with signs of pyelonephritis or systemic infection should also be investigated.
| Investigation | Indications |
|---|---|
| Culture of MSU, or urine obtained by suprapubic aspiration | All patients |
| Microscopic examination or cytometry of urine for white and red cells | All patients |
| Dipstick examination of urine for nitrite and leucocyte esterase | All patients |
| Dipstick examination of urine for blood, protein and glucose | All patients |
| Full blood count | Infants, children, adults with acute pyelonephritis or prostatitis |
| Plasma urea, electrolytes, creatinine | Infants, children, acute pyelonephritis, recurrent UTI |
| Blood culture | Fever, rigors or evidence of septic shock |
| Pelvic examination | Women with recurrent UTI |
| Rectal examination | Men (to examine prostate) |
| Renal ultrasound or CT | To identify obstruction, cysts, calculi Infants, children, men after single UTI Women who have (1) acute pyelonephritis, (2) recurrent UTI after antibiotic therapy, (3) UTI or asymptomatic bacteriuria in pregnancy |
| Micturating cysto-urethrogram (MCU) or radioisotope study | Selected infants and children to look for reflux and renal scars |
| Cystoscopy | Patients with haematuria or a suspected bladder lesion |
A. Asymptomatic bacteriuria. Defined as > 105/ml organisms in the urine of apparently healthy asymptomatic patients. Approx. 1% of children under the age of 1, 1% of schoolgirls, 0.03% of schoolboys and men, 3% of non-pregnant adult women and 5% of pregnant women have asymptomatic bacteriuria. There is no evidence that this condition causes renal scarring in adults who are not pregnant and have a normal urinary tract, and in general, treatment is not indicated. In infants and pregnant women, treatment is required and investigation is indicated.
B. Symptomatic acute urethritis and cystitis (previously described)
C. Acute pyelonephritis. The kidneys are infected in a minority of patients with lower urinary tract infection or bacteriuria. Acute renal infection (pyelonephritis) presents as a classic triad of unilateral or bilateral loin pain, fever and tenderness over the kidneys. Pain may radiate to the iliac fossae and suprapubic area. About 30% have dysuria due to associated cystitis. Fever is usually present and may be associated with rigors, vomiting and hypotension. The differential diagnosis includes acute appendicitis, diverticulitis, cholecystitis and salpingitis.
D. Acute prostatitis. It can be caused by the same bacteria that are associated with UTI or, more commonly, may be non-bacterial (no organisms cultured from urine). Clinical features include frequency, dysuria, perineal or groin pain, difficulty passing urine and, in acute disease, considerable systemic disturbance. The prostate is enlarged and tender.
E. Septicaemia (usually Gram-negative bacteria) May complicate cystitis in compromised host. Pyelonephritis, renal abscess (intrarenal or extrarenal), acute prostatitis or prostatic abscess can cause septicaemia in an immunocompetent host. May present as fever or hypothermia (seen principally in the elderly), tachycardia, tachypnoea and inadequate organ perfusion or function (altered mental state, hypoxaemia, oliguria).
Organisms causing UTI in the community include:
In hospital, E. coli still predominates, but Klebsiella or streptococci are more common than in the community.
The first stage in the development of UTI is colonization of the periurethral zone with pathogenic organisms. Urine is an excellent culture medium for bacteria; in addition, the urothelium of susceptible persons may have more receptors to which virulent strains of E. coli become adherent. In women, the ascent of organisms into the bladder is easier than in men because of the relatively short urethra and absence of bactericidal prostatic secretions. Sexual intercourse may cause minor urethral trauma and transfer bacteria from the perineum into the bladder.
Some patients, usually female, have symptoms suggestive of urethritis and cystitis but no bacteria are cultured from the urine (the 'urethral syndrome'). Possible explanations include infection with organisms not readily cultured by ordinary methods (e.g. Chlamydia, certain anaerobes), intermittent or very low-count bacteriuria, symptoms related to sexual intercourse, post-menopausal atrophic vaginitis, trigonitis or interstitial cystitis. Antibiotics are not indicated.