Acute pyelonephritis


Pyelonephritis is an acute infection of the renal parenchyma, potentially severe, especially in pregnant women, neonates and infants. The pathogens causing pyelonephritis are the same as those causing cystitis (see Acute cystitis).

Clinical features

Neonates and infant

– Symptoms are not specific: fever, irritability, vomiting, poor oral intake. Palpation of the lower abdomen may show abdominal tenderness. The absence of fever does not rule out the diagnosis. On the other hand, fever –with no obvious cause– may be the only manifestation.
– Neonates may present with fever or hypothermia, altered general condition, altered conscious state, pale/grey colour, shock.

In practice, a urinary tract infection should be suspected in children with unexplained fever or septic syndrome with no obvious focus of infection.

Older children and adults

– Signs of cystitis (burning on urination and pollakiuria, etc.)
AND
– Fever > 38.5 °C and flank pain (often unilateral) or abdominal tenderness

Laboratory

See Acute cystitis.

Treatment

– Antibiotherapy in children

• Children under one month
cefotaxime slow IV (3 minutes) for 10 days
Children 0 to 7 days (< 2 kg): 50 mg every 12 hours
Children 0 to 7 days (≥ 2 kg): 50 mg every 8 hours
Children 8 days to < 1 month: 50 mg every 8 hours
or
ampicillin slow IV (3 minutes) for 10 days
Children 0 to 7 days (< 2 kg): 50 mg every 12 hours
Children 0 to 7 days (≥ 2 kg): 50 mg every 8 hours
Children 8 days to < 1 month: 50 mg every 8 hours
gentamicin slow IV (3 minutes) for 5 days
Children 0 to 7 days (< 2 kg): 3 mg/kg once daily
Children 0 to 7 days (≥ 2 kg): 5 mg/kg once daily
Children 8 days to < 1 month: 5 mg/kg once daily

• Children one month and over
ceftriaxone IM or slow IV1 (3 minutes): 50 mg/kg once daily until the child's condition improves (at least 3 days) then change to oral route to complete 10 days of treatment with
amoxicillin/clavulanic acid PO (dose expressed in amoxicillin):
Children < 40 kg: 25 mg/kg 2 times daily 
Children ≥ 40 kg:
Ratio 8:1: 2000 mg daily: 2 tablets of 500/62.5 mg 2 times daily
Ratio 7:1: 1750 mg daily: 1 tablet of 875/125 mg 2 times daily 

– Antibiotherapy in adults

• Pyelonephritis with no signs of serious illness
ciprofloxacin PO: 500 mg 2 to 3 times daily for 7 days
or
cefixime PO: 200 mg 2 times daily for 10 to 14 days

• Presence of signs of serious illness (vomiting, patient seen late in disease, sepsis) or patient is in poor general condition (e.g. malnutrition, presence of other diseases)
ceftriaxone IM: 1 g once daily for at least 3 days,
then change to oral treatment with cefixime PO: 200 mg 2 times daily to complete 10 to 14 days of treatment (up to 21 days depending on clinical response)
gentamicin IM: 3 to 5 mg/kg once daily for 3 days (if sepsis)
or, if not available:
ampicillin slow IV (3 minutes): 2 g every 6 hours for at least 3 days
gentamicin IM: 3 to 5 mg/kg once daily for 3 days
then change to oral treatment with amoxicillin PO: 2 g 2 times daily to complete 10 to 14 days of treatment

– Treatment of fever and pain: use paracetamol rather than NSAID (Fever, Chapter 1).

– Maintain proper hydration (1.5 litre daily in adults), especially in children (risk of dehydration); treat dehydration if present (Appendix 2).

– Management of septic shock if needed.



Footnotes
Ref Notes
1

The solvent of ceftriaxone for IM injection contains lidocaine. Ceftriaxone reconstituted using this solvent must never be administered by IV route. For IV administration, water for injection must always be used.