Pharmacy First: Tips for diagnosing and treating infected insect bites

CLINICAL UPDATE

Most community pharmacies in England are now running the Pharmacy First service which enables them to diagnose and treat seven specific conditions. Under the service, pharmacists can prescribe set medications where appropriate, without recourse to a GP. This will hopefully reduce some of the current pressures on general practice.

This series of guides assumes that pharmacists are familiar with the clinical pathways and requirements for Pharmacy First. The articles explore some key aspects of each service to support and enhance pharmacists’ knowledge.

Here, GP Dr David Coleman offers his tips on managing infected insect bites in line with the Pharmacy First service.

Infected insect bites

It is common for patients to present to primary care settings with insect bites and stings, especially in the summer months. Insect bites account for on average 5.4 GP consultations per 100 000 patients per week in England and Wales.¹

The majority of local reactions to insect bites settle down or resolve completely within hours but can persist for longer.² The cause of these reactions is likely to be inflammatory or an allergic response and these cases do not require treatment with antibiotics.

Here are some tips on how to assess and manage presentations of suspected infective insect bites appropriately and in line with the new Pharmacy First service.

1. Safety first: beware the red flags

As is the case for the other Pharmacy First pathways, the first stage of the clinical algorithm for infected insect bites outlines symptoms of concern. Some patients who believe they have an infected bite may have more serious pathology.

The primary concerns are based around severe allergic reaction or anaphylaxis and significant infection. Clinicians are advised to beware signs of anaphylaxis and to respond immediately by administering adrenaline in line with the algorithm for that emergency.

If the patient is clearly unwell secondary to infection, and especially if they are immunocompromised, the assessing clinician is advised to arrange a 999 ambulance, and consider calculating a NEWS2 score. Periorbital cellulitis secondary to a bite close to the eye and airway obstruction are both listed as prompts for an emergency response as well.

As ever, safety first is the key for all of the Pharmacy First pathways.

2. Remember the scope of the pathway – refer any unusual bites on

Not all bite presentations will be appropriate for the pathway. It goes without saying that any bites that may be from animals or humans should be addressed in a more appropriate setting. Tick bites where there is a concern over Lyme disease, such as in the presence of the characteristic red Bull’s eye type rash called erythema migrans, are better seen by a GP. Bites that occurred overseas or where a more exotic or rare insect was implicated may also be more appropriate for a GP setting, as consideration may need to be given to infectious diseases

3. Self-care is key for early presentations

Infection of insect bites is a secondary occurrence; it is very rare in the early stages. For this reason, patients presenting with bites within the first 48 hours should be advised to self care. Oral antihistamines or topical corticosteroids can be used for symptom management, but there is no role for antibiotics at this stage.

Some useful specifics for self-care are as follows:

• Advise the patient to draw a line (with a ballpoint pen or felt tip) around the outer margins of the erythema, and to seek further advice if it spreads beyond this border
• Recommend daily photos of the bite on a mobile phone. This will help a clinician appreciate the progress of the bite if they are required to follow-up down the line.
• Explain the purpose of reducing itching – not just for comfort but to reduce infection risk by breaking the itch-scratch cycle.

4. After 48 hours, focus on itch versus pain

This is a simplification, but it is still a useful one and the pathway is built around this. If itch is the predominant symptom, allergy or inflammation is the most likely cause and the clinician is recommended to offer self-care advice.

If pain, tenderness, swelling or warmth is the main feature, infection is more likely and a deeper dive into the symptoms is warranted. If the redness is spreading or there is evidence of pus or discharge, the gateway point in the algorithm is reached, leading to an outcome of antibiotics or referral if there are any complication concerns (significant relevant co-morbidities, signs of systemic upset, severe pain).

5. Be ready for ‘I usually get antibiotics for this’

It is not uncommon for GPs to prescribe antibiotics for insect bites. A retrospective study looking at prescribing habits showed that around ‘two-thirds of the patients presenting to out-of-hours primary care with insect bites receive antibiotics’.³ While it is impossible to say if this prescribing was appropriate or not, it does seem a very high percentage. Consequently, it is possible many patients presenting to Pharmacy First will have a hope or expectation of antibiotics.

The clinical algorithm is quite clear and should not generate the proportion of antibiotic prescriptions seen in the above study. This may lead to some disappointment.

Being clear about how Pharmacy First works at the outset is key. This is a clinical pathway based on evidence; there is no scope for deviation. If self-care is recommended it is because it is the most appropriate option and there is no wiggle room.

6. Beware potential pitfalls – take a careful history and consider differentials

There are a few conditions that can be mistaken for infected insect bites that are not bite related at all. While a clear history will often point us in the right direction, not every patient will have seen the bite occur and they may just be looking for a plausible explanation for a new lesion themselves.

Conditions such as erythema nodosum can be hard to distinguish from inflamed or infected insect bites.⁴ This is a condition that typically involves red tender patches of skin on the lower limbs. It usually lasts longer than an insect bite and can be associated with acute infections, a medication reaction, or inflammatory bowel disease.

Other differential diagnoses related to the skin include folliculitis, cellulitis, viral conditions such as Chicken pox, urticaria, and even some skin tumours.⁵

7. Seize the opportunity for opportunistic health promotion

Prevention is better than cure. Use the opportunity provided by the patient’s presentation to counsel them about bite prevention in the future. The chief methods are wearing more appropriate (longer) clothing and using insect repellant. There are some useful patient resources online such as this ‘bug-off’ website, which has a travel focus.

8. Always give specific safety-netting advice

The specific safety-netting advice provided will depend on the presentation of the insect bite and its management. If the bite is treated with antibiotics as an infected bite, the treating clinician should suggest the patient seeks advice if their condition worsens or if the bite does not sufficiently improve after five days of treatment.

If the management is geared towards self-care, I would typically be advising the patient to watch out for signs of serious illness and also of worsening pain; as discussed in tip 4, pain can be suggestive of potential infection.

This is the latest in a series of articles on aspects of Pharmacy First from The Pharmacist.  

Dr David Coleman is a GP partner and trainer and PCN clinical director in south Yorkshire