Assessing a Patient with Suspected Infection

Clinical Uses of Antibiotics 1

When infections occur, there are usually signs. For example, we can use signs of local inflammation (heat, swelling, redness, pain) to identify the infection, or the signs associated with systemic manifestations (such as fever, raised heart rate, delirium).

However, infection is not always obvious. Why can infection be difficult to recognise, particularly in older people and children?

Infection may occur with or without fever or local symptoms.

• Older people may present with confusion or a decline in function, often with fever

• Children may initially compensate well, making serious illness difficult to recognise before their condition deteriorates

Why can’t symptoms alone diagnose or rule out infection?

Symptoms and signs can have other causes (differential diagnoses) that also need to be identified and managed.

What does differential diagnosis mean?

A differential diagnosis is a list of possible conditions that could be causing a patient's symptoms.

Which investigations can help identify or confirm an infection?

Blood tests that identify:

• White blood cell count

• Inflammatory markers

Blood cultures

Site-specific tests:

• Chest X-ray

• Urine culture

• Sputum culture

Test for other key differential diagnoses

When prescribing an antibiotic to treat an infection, you have to weigh out the balance between the potential harms of not treating, and the harms of treating.

What are the harms of not treating, and what are the harms of treating?

Harms of not treating:

• Probability of bacterial infection

• Severity and prognosis of infection

• Patient risk factors for severe infection / complications

• Risk of transmission

Harms of treating:

• Missed differential diagnosis

• Adverse effects of antibacterials

• Antibacterial stewardship

What is acute cellulitis?

Definition: An acute bacterial infection of the dermis and subcutaneous tissue

PC: Hot, red, swollen, painful skin. Usually lower limb. Can present blisters, fever, malaise, nausea

Common pathogens: Staphylococcus aureus, Streptococcus pyogenes

Differential diagnoses: Deep vein thrombosis, septic arthritis, gout

What factors should be assessed in acute cellulitis to guide antibiotic choice and treatment setting?

• Infection risk factors: cellulitis on face (peri-orbital cellulitis needs to be sent to hospital), unusual pathogens, MRSA status

• Risk of complications: Ulcers, nectroising fasciitis, sepsis

• Patient risk factors: Diabetes, vascular disease, immunocompromised, age

How is acute cellulitis managed in community (patients who do not need hospital admission)?

• Flucloxacillin = Antibiotic taken orally = 500-1000mg QDS for 5-7 days

• Fluids and paracetamol / ibuprofen for pain and fever

• Elevate the affected leg to reduce swelling

• Use emollients to prevent dry, cracked skin

• Safety netting: when to seek help

Do sore throats need antibiotics?

Not usually, because sore throats are usually:

• Common

• Caused be a viral infection

• Self limiting within 1 week

Antibiotics make very little difference to symptoms

What is the common advice for sore throats?

• Drink fluids

• Take ibuprofen and paracetamol

• Take medication lozenges

• Avoid hot drinks

What is the common bacterial cause of a sore throat?

Group A streptococcus (GAS)

• You need to treat GAS with antibiotics to prevent acute rheumatic fever, reduce severity, and prevent transmission

How do you diagnose whether a sore throat is caused by a bacterial infection?

We use the FeverPAIN score

It assesses the likelihood of a sore throat being caused by a bacterial infection and guide antibiotic prescribing

• Fever (> 38°) +1

• Purulence (pharyngeal/tonsillar exudate) +1

• Attend rapidly (within 3 days of onset) +1

• Severely Inflamed tonsils +1

• No cough or coryza (cold symptoms) +1

Consider an antibiotic for a sore throat if:

FeverPAIN score is 4-5 and there are severe symptoms, or patient not getting better

If you suspect epiglottitis, call 999. Do not examine the throat.

What is epiglottitis?

Definition: Inflammation of the epiglottis

Symptoms:

• Severe sore throat

• Stridor

• High fever

• 4Ds:

  • Dysphonia

  • Drooling

  • Dysphagia

  • Distress

Which diagnoses should be recognised in a patient presenting with a sore throat?

Infectious mononucleosis (glandular fever) = Fever and sore throat lasting more than a few days, particularly in young adults with lymphadenopathy.

Group A Streptococcus (scarlet fever / iGAS) = Sandpaper rash and strawberry tongue

Retropharyngeal or peritonsillar abscess (quinsy)

Lemierre syndrome

Diphtheria

Measles

HIV

Oropharyngeal cancer

Leukaemia

Behcet’s syndrome

Kawasaki’s disease

What is sepsis?

A life-threatening medical emergency that happens when your immune system has an extreme, toxic overreaction to an infection, damaging its own tissues and organs rather than just fighting the germs.

With sore throats, what signs indicate urgent hospital admission?

• Severe illness: Stridor or breathing difficulty; clinical dehydration; marked systemic illness.

• Severe complication: e.g. Peri-tonsillar abscess/cellulitis, quinsy.

• Suspected urgent cause: such as Kawasaki disease, diphtheria.

• Patient at high risk: e.g. immunocompromised, infant, very old.

How do we safety net with a sore throat?

Advise to seek follow up if:

• Symptoms have not improved after a week (reconsider antibiotic treatment or alternative diagnoses)

• Urgent if any signs of sepsis, difficulty breathing, difficult swallowing saliva or liquids, severe pain, one sided neck or throat swelling, severely unwell. Trust your instincts, if you suspect sepsis, act on it