Synopsis
Recognise urinary infection with organ dysfunction, deliver risk-appropriate early treatment and verify that any obstructed, infected or retained source has been controlled.
- In a nonpregnant adult in hospital, use NEWS2 with clinical judgement; a score of seven or more with suspected infection indicates high risk, and concern can escalate a lower score.
- For high risk suspected sepsis, give an appropriate broad intravenous antibiotic within one hour of the initial emergency department NEWS2 assessment or ward deterioration assessment. For a later directed cefalexin switch, exclude cephalosporin allergy and obtain specialist selection after a severe penicillin reaction.
- NG253 adult sepsis fluid resuscitation starts with 250 ml isotonic crystalloid over ten to fifteen minutes, reassessing after every bolus and counting prior fluids towards 1000 ml.
Key red flags
New confusion, hypotension, oliguria, acute kidney injury, rising oxygen requirement or lactate elevation should change urgency. Moderate-risk patients with hypoperfusion, such as lactate above 2 or acute kidney injury, are managed as high risk.
Confirm pregnancy or recent pregnancy and recent anticancer treatment at first assessment. Maternal sepsis uses its own risk and fluid recommendations; suspected neutropenic sepsis requires immediate cancer-specific empirical treatment rather than waiting for a routine score threshold.
Reasoning priorities
Identify invasive infection and quantify current organ effects.
Send blood cultures and blood gas with glucose and lactate, full blood count, renal function, liver tests, CRP and coagulation studies for high-risk illness. Collect before antibiotics where feasible, while ensuring the high-risk treatment window is met.
Worked reasoning
A fifty year old nonpregnant woman deteriorates five days after a kidney stone procedure.
- She has rigors, right flank pain, blood pressure 88/54, respiratory rate 26 and new confusion. Blood and urine cultures are collected during urgent senior assessment. She weighs 60 kg, is 165 cm tall, has creatinine 70 micromol/litre with calculated creatinine clearance about 80 ml/min, no beta lactam allergy and no aminoglycoside contraindication or interacting nephrotoxic drug.
- Under the cited Oxford adult urinary-sepsis protocol she receives amoxicillin 1 g intravenously every eight hours plus an initial gentamicin dose of 300 mg intravenously, each prepared and administered separately. A 250 ml isotonic crystalloid bolus runs over ten to fifteen minutes, followed by reassessment; further 250 ml boluses are given only while examination supports them, with previous fluids included in the total. NG253’s initial adult bolus is not a 500 ml maternal schedule or a preassigned litre or weight-based three-hour volume; each next bolus depends on reassessment.
- After initial treatment she remains poorly perfused, prompting in-person senior and critical care review rather than passive observation. Urgent CT shows a loculated perinephric collection with patent urinary drainage. Interventional radiology drains the collection and sends pus for culture; simply exchanging a freely draining bladder catheter would not control this source.
- Within six hours of drainage her blood pressure and mental state improve and lactate falls from 4.2 to 1.8. Gentamicin sampling is obtained in the protocol’s six to fourteen hour window and renal function is followed; subsequent dosing requires the actual result and protocol interpretation, not an automatic daily order.
- Cultures identify susceptible Escherichia coli. Microbiology narrows treatment, stops gentamicin within forty eight hours and later selects cefalexin 1 g orally three times daily once she is stable and eating. Three intravenous days plus seven oral days complete an agreed ten day complicated-infection course; the drain is removed after clinical and radiological review confirms control.
Key medicines
Amoxicillin 1 g intravenous powder with gentamicinIn the cited Oxford adult urinary-sepsis regimen, give amoxicillin 1 g intravenously every eight hours, infused over twenty to thirty minutes, alongside the separately prescribed gentamicin component.Do not use amoxicillin alone as presumed universal empirical Gram-negative cover. Exclude penicillin hypersensitivity or a severe immediate reaction to another beta lactam. The selected intravenous product adjusts at GFR 10–30 ml/min, including 30: give 1 g initially, then 500 mg to 1 g every twelve hours; below 10, give 1 g initially then 500 mg daily. Dialysis requires the separate product schedule. Check sodium burden, rash, diarrhoea and crystalluria with poor urine output, and review methotrexate and anticoagulants. Never mix amoxicillin and an aminoglycoside in the same syringe, infusion container or giving set.
Gentamicin 40 mg per ml injection or infusionFor the worked adult with calculated clearance about 80 and dosing weight 60 kg, Oxford’s 5 mg/kg initial dose is 300 mg intravenously, infused over thirty minutes; draw a level six to fourteen hours after administration.Use Oxford’s Cockcroft–Gault and dosing-weight method, rounding down to 20 mg increments. At creatinine clearance 31 ml/min or greater, the 5 mg/kg initial dose is capped at 480 mg and a six-to-fourteen-hour level is plotted on the specified nomogram to select the supported twenty four, thirty six or forty eight hour interval. At clearance 30 or less, start 3 mg/kg, maximum 240 mg, take a level at twenty four hours and withhold further doses until it is below 1 mg/litre; discuss dialysis with the renal team before the initial dose. Check renal function daily and stop for deterioration or toxicity; Micro/ID agreement is required beyond three days. Myasthenia gravis and gentamicin or formulation hypersensitivity are contraindications. Oxford also excludes known familial susceptibility to aminoglycoside toxicity. Suspected mitochondrial risk or a maternal deafness history requires specialist assessment of alternatives; it is not the same as a confirmed drug allergy. Review nephrotoxic, ototoxic and neuromuscular-blocking combinations.