Urinary tract infections

Urinary tract infections

Terms Cystitis Pyelonephritis

Aetiology

Vesicoureteric reflux Male/ female

Any anatomical abnormality of the tract, eg tumour, scaring

Enlarged prostate Stasis

Catheters and instrumentation Stones - bacteria get into the stones

Glucosuria Start of sexual activity in women

Haematogenic infections are also possible

Common pathogens

Coliform infection - Escherichia coli, Streptococcus faecalis, Proteus, Pseudomonas

Diagnosis

Lower tract infection - detection of pus cells, detection of nitrite

Prevent contamination of MSU by preventing contact with adjacent tissues

EMU to look for TB MSU for C and S

IVP Ultrasound

Isotope studies Cystoscopy

Pathophysiology

Bacterial infection of the urothelial surface

Interstitial cystitis may develop in the bladder wall with clear cultures - mostly in middle aged

women

Asymptomatic bacteriuria occur in 5 - 10% of women and is probably caused by sex

Clinical features Blood and pus in urine

Cystitis frequency, dysuria, urgency

Acute Pyelonephritis loin pain, fever, malaise, usually bilateral

Chronic Pyelonephritis

The end result of chronic infection often from childhood

Small, distorted asymmetrical kidneys Loin pain and tenderness

Possible hypertension Question about intake of NSAIDs

Culture, antibiotics, creatinine clearance tests

Prevention

Adequate fluid intake Ensure bladder is fully emptied Empty bladder after sex

Pregnancy

UTIs are common in pregnancy May ascend to the kidneys leading to premature delivery

Should be screened for bacteria in urine at first prenatal visit and given antibiotics if indicated

In children

2% of boys and 8% of girls develop UTIs in childhood

Reflux may cause UTI

Vesicoureteric reflux present in 8 - 40% of cases

Renal scaring may develop

Always culture if any suspicion of UTI

Refer all children with UTI for investigations

Treatments

High fluid intake Antibiotics Prophylactic antibiotics Surgery

DEFINITION

UTI is defined by the presence of a pure growth of more than 10⁵ colony forming units of bacteria per ml. Lower counts of bacteria may be clinically important, especially in boys and in specimens obtained by urinary catheter. Any growth of typical urinary pathogens is considered clinically important if obtained by suprapubic aspiration. In practice, three age ranges are usually considered on the basis of differential risk and different approaches to management: children under 1 year; young children (1–4, 5, or 7 years, depending on the information source); and older children (up to 12–16 years). Recurrent UTI is defined as a further infection by a new organism. Relapsing UTI is defined as a further infection with the same organism.

PREVALENCE

Boys are more susceptible before the age of 3 months; thereafter the incidence is substantially higher in girls. Estimates of the true incidence of UTI depend on rates of diagnosis and investigation. At least 8% of girls and 2% of boys will have a UTI in childhood.

AETIOLOGY

The normal urinary tract is sterile. Contamination by bowel flora may result in urinary infection if a virulent organism is involved or if the child is immunosuppressed. In neonates, infection may originate from other sources. Escherichia coli accounts for about three quarters of all pathogens. Proteus is more common in boys (about 30% of infections). Obstructive anomalies are found in 0–4% and vesicoureteric reflux in 8–40% of children being investigated for their first UTI. Although vesicoureteric reflux is a major risk factor for adverse outcome, other as yet unidentified triggers may also need to be present.

PROGNOSIS After first infection, about half of girls have a further infection in the first year and three quarters within 2 years. We found no figures for boys, but a review suggests that recurrences are common under 1 year of age but rare subsequently. Renal scarring occurs in 5–15% of children within 1–2 years of their first UTI, although 32–70% of these scars are noted at the time of initial assessment. The incidence of renal scarring rises with each episode of infection in childhood. An RCT comparing oral versus intravenous antibiotics found retrospectively that new renal scarring after a first UTI was more common in children with vesicoureteric reflux than in children without reflux (logistic regression model: AR of scarring 16/107 [15.0%] with reflux v 10/165 [6%] without reflux; RR 2.47, 95% CI 1.17 to 5.24). A study (287 children with severe vesicoureteral reflux treated either medically or surgically for any UTI) evaluated the risk of renal scarring with serial DMSA
scintigraphy over 5 years. It found that younger children (under 2 years) were at greater risk of renal scarring than older children regardless of treatment allocation for the infection (AR for deterioration in DMSA scan over 5 years 21/86 for younger children v 27/201 for older children; RR 1.82, 95% CI 1.09 to 3.03). Renal scarring is associated with future complications: poor renal growth; recurrent adult pyelonephritis; impaired glomerular function; early hypertension; and end stage renal failure. A combination of recurrent urinary infection, severe vesicoureteric reflux, and the presence of renal scarring at first presentation is associated with the worst prognosis.

AIMS

To relieve acute symptoms; to eliminate infection; and to prevent recurrence, renal damage, and long term complications.

OUTCOMES

Short term: clinical symptoms and signs (dysuria, frequency, fever); urine culture; incidence of new renal scars. Long term: incidence of recurrent infection; prevalence of renal scarring; renal size and growth; renal function; prevalence of hypertension and renal failure.

UTIs in children

Aetiology

Vesicoureteric reflex is most common

Congenital obstructions

Bladder dysfunctions

Some forms of E. coli may adhere to the urinary endothelium so are not easily washed out

Presentation

Neonates

In neonates this is non-specific, e.g. poor feeding, vomiting, irratibility

May develop into sepsis with meningitis

Post neonatal

In young children presentation may include fever, irritability, diarrhoea, vomiting.

Features may look like a GI rather than a GU problem.

Frequency and dysuria are not reliable symptoms.

May or may not be suprapubic or loin tenderness.

School age children