Antibiotic guidelines

With the introduction of pharmacist prescribing for minor ailments, appropriate prescribing of antibiotics has gained increasing importance for pharmacists. On completion of this module, it is expected the reader will have an enhanced understanding of guidelines, evidence-based prescribing, and antimicrobial stewardship.

Introduction

Antimicrobial resistance is recognised by the World Health Organisation (WHO) as one of the greatest threats to global public health. Antibiotic resistance, a subset of antimicrobial resistance, occurs when bacteria evolve mechanisms to survive the antibiotics designed to eliminate them. This compromises treatment efficacy and makes bacterial infections increasingly difficult to control. Routine medical proce- dures, chemotherapy and minor infections could become significantly more danger- ous without effective antibiotics.

Recent estimates indicate that anti- microbial resistance causes over 35,000 deaths annually in Europe alone. Inappropriate or unnecessary antibiotic use is a primary driver of resistance. Studies suggest that up to 50 per cent of antibiotic prescriptions may be inappropriate, with antibiotics often prescribed for viral infections, where they offer no benefit. Beyond contributing to resistance, inappropriate antibiotic use increases the risk of adverse drug reactions and disrupts the patient’s normal microbiome.

National guidelines, including those issued by the National Institute for Health and Care Excellence (NICE) in the UK and the Health Service Executive (HSE) in Ireland, provide evidence-based recommendations for managing common infections. These guidelines support healthcare professionals in making informed decisions: Choosing the right antibiotic, at the right dose, for the correct duration, while recognising when antibiotics are not required.

Pharmacists play a crucial role in implementing these guidelines in practice. As highly accessible healthcare professionals, pharmacists are often the first point of contact for patients presenting with symptoms of infection. They can counsel patients on the differences between viral and bacterial infections, encourage adherence to prescribed antibiotic regimens, and promote vaccination as a preventive measure. By supporting guideline-based treatment, pharmacists help reduce inappropriate antibiotic use, improve clinical outcomes, and safeguard the effectiveness of antibiotics for future generations.

Principles of antibiotic use

The guiding principles of antibiotic use aim to ensure patients receive the most effective treatment while minimising unnecessary exposure, reducing adverse effects and preserving antibiotic efficacy. A fundamental principle is that antibiotics should only be used when there is clear evidence of bacterial infection. Many common illnesses are viral and self-limiting; in such cases, antibiotics offer no benefit. Antibiotic use in such cases exposes patients to potential harm without improving outcomes and contributes to antimicrobial resistance.

In cases where antibiotics are indicated, they should be carefully selected to target the most likely pathogens while considering local resistance patterns. Narrow-spectrum antibiotics are typically preferred, with broad-spectrum agents reserved for cases where clearly necessary. Optimal treatment requires careful attention to the right drug, dose, route and duration. Oral therapy is often preferred in communi- ty settings, with intravenous therapy reserved for severe infections or cases of impaired absorption. Duration should be the shortest effective course. Where possible, microbiological testing should be performed before starting treatment, allowing therapy to be reviewed, adjusted or discontinued based on culture results.

Evidence-based strategies — such as delayed prescriptions — can effectively reduce unnecessary antibiotic use. Patients are advised to use the antibiotic only if symptoms worsen or persist beyond a specified timeframe, while receiving guidance on self-care measures. ‘Safety-netting’ — informing patients when to seek further care — is essential for safety and good clinical outcomes. Potential risks of antibiotics, including adverse effects, should always be considered. These principles promote effective individual care while protecting antibiotic efficacy for future generations.

Guideline application in common infections Evidence-based antibiotic guidelines, such as those published by NICE, pro- vide a framework to optimise antibiotic use across common infections. Adher- ence to evidence-based recommendations ensures antibiotics are prescribed only when likely to benefit the patient, with appropriate drug, dose and dura- tion. While clinical judgement remains essential, guidelines help to standardise care and improve patient outcomes. The section below summarises the appli- cation of current NICE guidance to the most common community infections.

a) Upper respiratory tract infections (URTIs) URTIs, including tonsillitis, pharyngitis, acute otitis media and sinusitis, account for a large proportion of antibiotic use. Most cases are viral and self-limiting, making antibiotics largely unnecessary. Symptomatic management is often sufficient, including paracetamol or ibuprofen for pain or fever, medicated lozenges containing local anaesthetics or antiseptics, and adequate fluid intake. Patient education is critical, outlining the natural course of illness, symptomatic relief and red-flag symp- toms requiring medical review.

• Acute sore throat (pharyngitis/tonsillitis): Typically viral and self-limiting, not requiring antibiotics. Antibiotics may benefit patients who are systemically unwell, at high risk of complications, or have signs of severe illness. Recommended first-line therapy is phenoxymethylpenicillin 500mg four times daily for five-to-10 days. Clarithro- mycin 250–500mg twice daily for five days may be used in penicillin allergy. Age-based dosing should be applied in children.

• Acute otitis media: Particularly common in children and usually re- solves within 72 hours. Antibiotics are reserved for severe or prolonged cases. First-line treatment is amoxicillin for five-to-seven days, with clarithromycin as an alternative in penicillin allergy.

• Acute sinusitis: Typically self-limiting. Antibiotics are indicated only for persistent or worsening symptoms beyond 10 days, severe presentations or high- risk patients. Phenoxymethylpenicillin 500mg four times daily for five days is first-line treatment, while co-amoxi- clav 500/125mg three times daily for five days may be considered in severe illness. Alternatives for penicillin-allergic patients include doxycycline (200mg on day one, then 100mg daily for four days) or clarithromycin 500mg twice daily for five days.

b) Lower Respiratory Tract Infections (LRTIs)

• LRTIs include acute bronchitis, chronic obstructive pulmonary disease (COPD) exacerbations, and pneumonia. They represent a substantial proportion of primary care antibiotic use, necessitating careful diagnosis and targeted treatment.

• Acute bronchitis: Most often caused by a viral infection and self-limiting, with symptoms lasting three-to-four weeks. Antibiotics generally do not improve the clinical condition or shorten the duration of symptoms. If indicated, first-line treatment is doxycycline 200mg on day one, then 100mg daily for four days. In children, age-based amoxicillin dosing is preferred, with clarithromycin or erythromycin for penicillin allergy.

• COPD exacerbations: Defined as a sustained worsening of symptoms from a person’s stable state. This is often triggered by viruses, smoking or bacteria, requiring careful assessment. Antibiotics are indicated for bacterial exacerbations, considering symptom severity, sputum purulence, sputum volume and prior culture results. Amoxicillin, doxycycline and clarithromycin are all typically first-line antibiotic choices, with a duration of five days. Second-line options include an alternative first-line agent.

• Community-acquired pneumonia (CAP): A serious infection that requires prompt recognition and management.

In primary care, clinical judgement plus assessment tools such as CRB-65 can help determine severity and need for hospital referral. CRB-65 assesses severity based on confusion, raised respiratory rate, low blood pressure and age ?65 years to determine treatment approach. For mild cases managed in the community, amoxicillin 500mg three times a day is first-line treatment, with doxycycline or clarithromycin alterna- tives in penicillin allergy. In moderate disease, higher doses of amoxicillin may be considered plus clarithromycin. In cases of severe illness, co-amoxiclav and clarithromycin may be administered intravenously. Treatment duration is typically five days but may be extended if clinically indicated.

c) Urinary tract infections (UTIs)

UTIs are one of the most common bacterial infections managed in primary care, with women disproportionately affected. High-risk groups include men, older adults, catheterised patients, children, pregnant women and patients with recurrent infections. These patients may require more cautious management, with urine cultures recommended before treatment. Duration of treatment is often extended in these patient groups. Overall, guide- lines encourage the shortest effective course, with culture-guided prescribing in complicated cases and avoidance of unnecessary antibiotic use. fNon-pregnant women aged 16 years and over: First-line treatment is nitrofu-

rantoin 100mg modified release twice daily for three days (or 50mg four times daily if MR formulation unavailable). Trimethoprim 200mg twice daily for three days may be used if local resistance rates are low. If these agents are unsuitable or resistance is suspected, second-line options include fosfomycin 3g as a single dose. Fosfomycin should be taken on an empty stomach, after bladder emptying, to maximise absorption and contact time.

• Pregnant women aged 16 years and over: Trimethoprim should be avoided in pregnancy, with nitrofurantoin 100mg modified release twice daily for seven days the recommended treatment. Ni- trofurantoin should be avoided at term due to the risk of neonatal haemolysis. Alternatives such as cefalexin or amoxi- cillin may be used, depending on culture results and susceptibility.

• Men and children: UTIs in men are often considered complicated, with nitrofurantoin or trimethoprim for seven days as first-line options. Children require more cautious management, with referral to a paediatric specialist for intravenous antibiotic treatment recommended in infants aged under three months. In children over three months of age, trimethoprim and nitrofurantoin are considered first-line options, with amoxicillin and cefalexin as second-line options based on urine cultures. Weight-based dosing should be used. fAcute pyelonephritis: Defined as an infection of one or both kidneys typical- ly caused by bacteria travelling up from the bladder. A midstream urine sample should be obtained before treatment and sent for culture and susceptibility testing. It requires culture-guided antibiotic treatment to achieve thera- peutic concentrations in renal tissue. In non-pregnant women and men older than 16 years, cefalexin 500mg two-to- three times daily for seven-to-10 days, co-amoxiclav 500/125mg three times daily for seven-to-10 days, trimethoprim 200mg twice daily for 14 days, or ciprofloxacin 500mg twice daily for seven days are all considered first-line treatment options, depending on culture results. In pregnant women, cefalexin 500mg two-to-three times daily for seven-to-10 days is first-line, while cefuroxime may be considered intravenously. In those under 16 years, oral co-amoxiclav and cefalexin are first choice treatment.

d) Skin and soft tissue infections

Skin and soft tissue infections are commonly seen in primary care, ranging from mild, localised disease, to severe and systemic illness.

• Impetigo: Frequently presents, particularly in children. Localised, non-bullous impetigo in adults and children should be treated with topical hydrogen perox- ide 1%, if possible. Topical fusidic acid 2% may be used if hydrogen peroxide is unsuitable, ineffective or not avail- able. Mupirocin 2% may be considered if fusidic acid resistance is suspected.

Widespread or bullous disease in adults and children may require oral flucloxacillin, with clarithromycin being used if the patient has a penicillin allergy or if flucloxacillin is unsuitable. Five-day treatment is the typical duration for both topical and oral antibiotics.

• Secondary bacterial infection in eczema: An antibiotic should not be routinely offered in patients who are not systemically unwell. If an antibiotic is indicated, fusidic acid 2% is the first- line topical antibiotic. If an oral antibiotic is required, flucloxacillin is recommended, with clarithromycin in the case of allergy. These recommendations are for both and adults and children, with a duration of treatment of five-to-seven days.

• Cellulitis: Most often caused by Streptococcus or Staphylococcus infection.

Oral antibiotics are indicated for patients with cellulitis, if the severity of the condition does not require intravenous antibiotics. If intravenous antibiotics are required, the patient should be reviewed within 48 hours and consider switching to an oral antibiotic if possible. Patients should be reassessed if the symptoms worsen rapidly, do not start to improve within two-to-three days, or the person becomes systemically very unwell. Oral flucloxacillin 500mg–1g four times daily for five-to-seven days is first-line, with clarithromycin, erythromycin or doxycy- cline considered in the case of penicillin allergy.

Coamoxiclav is the first-line option if the infection is near the eyes or nose. In the case of severe infection, coamoxiclav, cefuroxime, clindamycin or ceftriaxone may be administered intravenously. If methicillin-resistant Staphylococcus aureus (MRSA) infec- tion is suspected or confirmed, vancomycin, teicoplanin and linezolid should be added to one of the above antibiotics under specialist consultation.

e) Sexually-transmitted infections (STIs)

STIs remain a significant public health concern in Ireland, with recent years seeing a sharp rise in reported cases. They can sometimes be asymptomatic in males and females. In males, infection can cause complications, such as prostatitis and infertility. In females, infection can lead to pelvic inflammatory disease, associated with an increased risk of tubal factor infertility, ectopic pregnancy and chronic pelvic pain. While antibiotics remain central to bacterial STI management, it is import- ant to note that they have no role in viral infections such as herpes simplex virus, human papillomavirus, human immunodeficiency virus and hepatitis. Partner notification, contact tracing and patient education are essential to the management of STIs.

• Chlamydia: The most commonly diagnosed bacterial STI, particularly in young adults. NICE guidelines now recommend doxycycline 100mg twice daily for seven days as the first-line treatment as it is more effective for urogenital, rectal and oropharyngeal sites, while also reducing resistance concerns. Azithromycin is reserved for pregnancy or doxycycline intolerance, with single dose regimens no longer recommended. The recommended dose is 1g on day one, followed by 500mg on day two and day three.

• Gonorrhoea: Presents a particular challenge due to an increase in incidence and in antibiotic resistance. Ceftriaxone is the mainstay of treatment, with guidance recommending a single deep intramuscular injection (1g) as first-line. Test-of-cure is advised to ensure eradication. In the case of cephalosporin allergy, referral to a specialist is recommended, with azithromycin 2g orally as a single dose and ciprofloxacin 500mg orally as a single dose being the main treatment options.

• Syphilis: A growing concern in Ireland, with notifications more than doubling over the past decade.

Parenteral penicillin is first-line treatment, with the type, dose, route and duration determined by the clinical presentation and stage of disease. Benzathine benzylpenicillin is commonly used, while doxycycline is an alternative for patients with penicillin allergy.

f) Dental Infections

The cornerstone of management of dental infections is timely dental intervention. Antibiotics should not be used as a substitute for drainage, extraction or other appropriate dental procedures, as they may not adequately eradicate infection in the presence of necrotic tissue or abscesses. Antibiotics should be reserved for cases with spreading infection, systemic symptoms, or where immediate dental care is not possible.

When antibiotics are indicated, phe- noxymethylpenicillin is the preferred antibiotic due to its narrow spectrum and efficacy against oral streptococci. Amoxicillin may be used as an alter- native where compliance is a concern, given its three-times-daily regimen versus four-times-daily for phenoxymeth-ylpenicillin.

For infections with suspected anaerobic involvement, metronidazole may be considered. In the case of penicillin allergy, metronidazole or clarithromycin may be used. The use of clindamycin and co-amoxiclav is not routinely recommended for the management of dental infections to limit resistance and minimise Clostridioides difficile risk.

g) Genital infections

Non-sexually transmitted genital infec- tions such as prostatitis, epididymo-or- chitis and bacterial vaginosis require careful antibiotic selection.

• Acute bacterial prostatitis: This is a medical emergency involving a serious bacterial infection of the prostate gland, typically characterised by pain on urination, urinary frequency, and systemic features (fever, malaise, myalgia). Management requires prompt treatment with antibiotics that achieve therapeu- tic concentrations in prostatic tissue. A midstream urine sample should be sent for culture and susceptibility testing to guide choice of antibiotic. Oral antibiotics are first-line if clinically appropriate. Fluoroquinolones (ciprofloxacin 500mg twice daily or ofloxacin 200mg twice daily) are first-line treatment, with trimethoprim (if local resistance rates allow) as an alternative first choice if fluoroquinolones are not suitable. Second-choice oral antibiotics, after discussion with a specialist, are levo- floxacin 500mg once daily or co-trimox- azole 960mg twice daily. The course of treatment is typically a minimum of 14 days, extended to 28 days depending on symptom resolution.

• Acute epididymo-orchitis: A painful syndrome caused by inflammation of the epididymis and testicle. Aetiology may be STI or UTI and therefore requires consideration of the under- lying cause. Non-STI causes often involve enteric gram-negative bacteria. Ciprofloxacin 500mg for 10-to-14 days is first-line treatment, due to its broad gram-negative and urinary pathogen coverage.

• Bacterial vaginosis: Arises from the disruption of the vaginal microbiota.

It is characterised by a white, non-ir- ritating, malodorous vaginal discharge in women of reproductive age. It is not considered to be sexually transmitted, although it is more common in sexually active women. Partner treatment is not recommended. First-line treatment is oral metronidazole 400mg three times daily for five-to-seven days, with topical or oral clindamycin an alternative.

h) Gastrointestinal Infections ccc, with unnecessary treatment increasing the risk of resistance and disrupting gut flora.

• Traveller’s diarrhoea: Often viral, with antibiotics providing no benefit. Antibiotic treatment is typically only indicated in patients who are at high risk of severe adverse outcomes. Supportive management with hydration remains the cornerstone of care. If antibiotics are indicated, azithromycin 1,000mg as a single dose or 500mg every 24 hours for three days is recommended as first- line.

• Clostridioides difficile infection (CDI): A major concern in healthcare settings and strongly linked to prior antibiotic exposure. The spectrum of CDI ranges from mild diarrhoea to potentially fatal colitis. Avoiding unnecessary broad-spectrum use is critical in prevention. First-line treatment for a first episode is vancomycin 125mg orally four times a day for 10 days. If vancomycin is ineffective, fidaxomicin 200mg orally twice a day for 10 days is second-line. If both first- and second-line antibiotics are ineffective, specialist advice should be sought. In refractory cases, vancomycin orally up to 500mg four times daily for 10 days, with or without metronidazole 500mg intravenously three times daily for 10 days may be considered. Faecal microbiota transplantation may be considered in refractory, recurrent infection. fHelicobacter pylori (H.pylori): Antibi- otic therapy is essential for eradication. Standard first-line treatment regimens are based on triple therapy, with a proton pump inhibitor, clarithromycin 500mg twice daily and amoxicillin 1g twice daily for seven days. Metroni-dazole 400mg every 12 hours may be used instead of amoxicillin in cases of penicillin allergy. Levofloxacin-based triple therapy, with levofloxacin 250mg twice daily replacing clarithromycin, should be reserved for second-line treatment in the case of failed eradi- cation. Post-eradication testing should be performed following completion of therapy.

Pregnancy and breastfeeding

Antibiotic choice also depends on patient factors such as pregnancy and lactation status. The use of antibiotics in pregnancy and breastfeeding requires careful consideration, balancing the need for effective maternal treatment with the safety of the infant. While certain antibiotics are safe,
some should be avoided due to risks of teratogenicity, neonatal toxicity and interference with development. Penicillins and cephalosporins are generally regarded as safe treatment options for most infections during pregnancy. In the case of penicillin allergy, erythromycin is typically the preferred macrolide. Nitro- furantoin remains first-line for treating UTIs, but it should be avoided at term due to the risk of neonatal haemolysis. Trimethoprim is generally avoided in the first trimester due to folate antagonism, unless no suitable alternative is avail- able and folic acid supplementation can be ensured.

Metronidazole may be used in pregnancy for specific infections, such as bacterial vaginosis. Antibiotics such as tetracyclines and fluoroquinolones are typically avoided unless essential due to risks including foetal bone effects, teeth damage and cartilage toxicity. Urine culture and susceptibility results, as well as previous antibiotic use, should guide choice of antibiotic in pregnancy.

Most commonly-used antibiotics are suitable in breastfeeding. Small amounts may pass into breast milk, but these rarely cause clinical issues. However, infants should be monitored for

gastrointestinal disturbance and signs of hypersensitivity. Nitrofurantoin, pen- icillins, cephalosporins, metronidazole and macrolides are typically considered safe.

Metronidazole short courses are generally safe, though prolonged high-dose regimens should be avoided. Long-term use of tetracyclines is not recommended due to potential deposition in develop- ing teeth and bones. In pregnancy and breastfeeding, the general principle is to use antibiotics only if clearly indicated, choose the safest agents, and use at the lowest effective dose for the shortest effective duration.

Role of the pharmacist

Pharmacists play a central role in anti- microbial stewardship and optimising antibiotic use.

As one of the most accessible health- care professionals, pharmacists are often the first point of contact for patients with symptoms of infection. This positions them in a unique position to provide education, reinforce guideline-based care, and reduce inappropriate antibiotic demand.

Pharmacists can counsel on the difference between bacterial and viral infections, outlining the natural course of infection and giving advice on effective self-care measures such as hydration, rest, and over-the-counter treatment. They can also identify red-flag symptoms that require urgent medical referral. Pharmacists can promote effective antibiotic use and discourage inappropriate use by setting realistic expectations and using strategies such as safety-netting and delayed prescriptions.

Pharmacists also support antibiotic stewardship through medicines optimisation. They review prescriptions thoroughly to ensure the correct drug, dose and duration in line with HSE and NICE guidelines. Potential interventions that pharmacists may make include checking for drug interactions, advis- ing on safe antibiotic use in pregnancy or breastfeeding, and counselling on adherence to ensure therapeutic effectiveness.

Pharmacists also have an increasingly important role in vaccination and infection prevention. By providing influenza, Covid-19 and pneumococcal vaccination, pharmacists help to significantly reduce the incidence of respiratory infections that may drive antibiotic demand.

This also reduces the risk of secondary bacterial infection after viral infection. Pharmacists can encourage vaccination in at-risk groups and provide advice on infection prevention, further limiting unnecessary antibiotic exposure.

By combining accessibility, expertise and communication, pharmacists form a cornerstone of strategies to preserve antibiotic effectiveness and safeguard public health.

References available on request

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