Especially in the elderly, ascertaining the source of a suspected infection based on history and clinical examination can be challenging, but it is unlikely for a patient to present with two concurrent infections affecting two different body systems such as "? chest / ? urine" or "? chest / ? SSTI (skin and soft tissue infection)". Refer to the relevant organ system sections for advice on appropriate narrow spectrum options.

If sepsis criteria are fulfilled, treat as sepsis without localising signs.

• 33% of gram negative isolates from blood cultures are resistant to co-amoxiclav, and 22% are resistant to ciprofloxacin/levofloxacin.
• Co-amoxiclav and ciprofloxacin/levofloxacin are antimicrobials with a particular high risk of causing C. difficile infection.

• Asymptomatic bacteriuria is common in older adults of both sexes, and should not be treated unless the patient is pregnant.
• Practically all catheter urines have a positive dipstick - this is not a sign of catheter-associated UTI (CAUTI).

• Cellulitis does not occur on both legs at the same time.
• The skin changes of chronic venous insufficiency look less livid if the leg has been elevated for at least 30 minutes.