Overview

Acute Pharyngitis is the inflammation of the mucous membranes of the back of the throat. It is predominantly caused by either bacterial or viral infections.¹

Acute pharyngitis is one of a clinician’s most frequent complaints in the ambulatory care setting usually, the occurrence peaks during childhood and adolescence. Although the number of annual visits for pharyngitis cases is huge, most of these cases are viral and tend to resolve on their own without needing medical intervention. However, Group A Streptococcus (GAS) stands out as the primary bacterial cause responsible for acute pharyngitis, commonly referred to as "strep throat."²

Patients with GAS pharyngitis usually report sore throat (typically of sudden onset), severe pain on swallowing, and fever. They may also experience headaches, nausea, vomiting, and abdominal pain. Examination commonly shows throat redness which may or may not be accompanied by oozing, tenderness, and swollen lymph nodes.³

The accurate diagnosis of GAS pharyngitis cannot be based solely on history and physical exam. For this reason, the Infectious Diseases Society of America recommends confirmatory bacterial testing with a rapid antigen detection test.²

The main goals of treatment for GAS pharyngitis include minimising a patient’s duration and severity of symptoms, prohibiting acute and delayed complications, and inhibiting the spread of infection to others.²

Even though most cases of pharyngitis will resolve on their own without treatment, antibiotics are prescribed in approximately 60% of cases to prevent rare complications (e.g., acute rheumatic fever, rheumatic heart disease, post-streptococcal glomerulonephritis), reduce the duration of illness, prohibit the spread of infection to close contacts and address patient needs.⁴

This article will delve into various antibiotics used for GAS pharyngitis, factors to consider when selecting them, and other intriguing facts.

Antibiotic therapy for GAS pharyngitis

When selecting an antibiotic for the treatment of GAS pharyngitis, crucial aspects to consider include efficacy, safety, antimicrobial spectrum (narrow versus broad), dosing schedule, compliance with therapy, and cost.⁵

Penicillin-based antibiotics

Penicillin V (Phenoxymethylpenicillin) is considered the treatment of choice because of its proven efficacy and safety, narrow spectrum, and low cost. Amoxicillin is often used instead of penicillin V as oral therapy for young children; the efficacy appears to be the same.⁵

Oral Penicillin V can be prescribed as either 250 mg twice or three times daily for children and 250 mg four times daily for adults. Suppose an intramuscular approach is preferred for administering penicillin treatment. In that case, benzathine penicillin G can be administered as a single dose of 600,000 units for patients weighing less than 27 kg and 1.2 million units for those weighing 27 kg or more.

Alternatively, if the prescriber opts for oral amoxicillin, the recommended dosage is 50 mg/kg once daily, with a maximum of 1000 mg per dose, or 25 mg/kg twice daily, with a maximum of 500 mg per dose. Regardless of the chosen route, whether penicillin V or amoxicillin, the entire 10-day course of treatment should be completed.²

Common side effects of penicillin V and amoxicillin include gastrointestinal upset and hypersensitivity reactions. Moreover, benzathine penicillin G may induce injection site reactions in addition to these side effects.⁶ People with documented hypersensitivity to penicillins, cephalosporins, and imipenem should avoid taking penicillin V and amoxicillin.^7,8

Macrolide antibiotics

For people allergic to penicillin, alternative treatments are recommended. One option is oral clarithromycin at a dosage of 7.5 mg/kg/dose given twice daily, with a maximum of 250 mg/dose, for 10 days. Alternatively, oral azithromycin can be prescribed at a dosage of 12 mg/kg once daily, with a maximum of 500 mg/dose, for a total duration of 5 days.²

Common adverse effects associated with both clarithromycin and azithromycin include altered cardiac conduction, gastrointestinal upset, and hepatotoxicity.⁹

Clarithromycin should be avoided in the following conditions:¹⁰

• Documented hypersensitivity
• Coadministration with pimozide, cisapride, ergotamine, and dihydroergotamine
• History of cholestatic jaundice or liver dysfunction linked to previous use of clarithromycin
• Coadministration with colchicine in patients with kidney or liver impairment
• Coadministration with statins such as lovastatin and simvastatin

Concerning azithromycin its use is prohibited in patients with hypersensitivity to azithromycin, erythromycin, or any macrolide and in those with a history of cholestatic jaundice or liver dysfunction associated with prior use of azithromycin.¹¹

Cephalosporin antibiotics

In cases where penicillin allergy is not severe and life-threatening, a first-generation cephalosporin such as oral cephalexin can be considered. The recommended dosage is 20 mg/kg/dose twice daily, with a maximum of 500 mg/dose, for a total of 10 days.²

Narrow-spectrum cephalosporins, such as cefadroxil or cephalexin, are more favourable than broad-spectrum cephalosporins, such as cefaclor, cefuroxime, cefixime, cefdinir, and cefpodoxime. Most oral broad-spectrum cephalosporins are significantly more expensive than penicillin or amoxicillin, and their selection is more likely to contribute to the development of bacteria that are resistant to the effects of the cephalosporins and thus make infection more difficult to treat.⁵ These remarkable concerns should be considered when making decisions about antibiotic therapy.

Common side effects associated with cefadroxil or cephalexin include gastrointestinal upset and hypersensitivity reactions. The indication of cephalosporins should be avoided if patients are allergic to them or have had a severe and life-threatening allergic reaction to penicillin or other beta-lactam antibiotics.¹²

Clindamycin

For individuals allergic to penicillin, a recommended alternative is oral clindamycin at a dosage of 7 mg/kg per dose, administered three times daily, with a maximum of 300 mg per dose. This prescription should be continued for a total duration of 10 days.²

Common side effects associated with clindamycin use include Clostridium difficile infection, gastrointestinal upset, and hepatotoxicity. It is important to note that individuals with hypersensitivity to clindamycin, lincomycin, or any of its formulation components should not take clindamycin.¹³

Symptom resolution and return to work 

Following the antibiotic treatment period, patients may see a recovery from symptoms within one to three days and may return to work or school after 24 hours of treatment. A test of cure is not recommended after a course of treatment unless a patient has a history of acute rheumatic fever or another GAS pharyngitis complication.² Please seek your GP if you see no improvement with your treatment and your symptoms have not gone or have gotten worse.

Patient education

Patients and parents should be counselled on bacterial and viral pharyngitis differences. People diagnosed with GAS infection should be encouraged to complete a full course of antibiotics to inhibit the risk of rheumatic heart disease. Besides, all patients with pharyngitis should be educated on the importance of handwashing, rest, and hydration.¹

Summary

• Acute pharyngitis is a common complaint in ambulatory care, especially prevalent in childhood and adolescence
• While most cases are viral and self-resolving, Group A Streptococcus (GAS) stands out as the leading bacterial cause
• Treatment goals for GAS pharyngitis include minimising a patient’s duration and severity of symptoms, prohibiting complications, and limiting the spread of infection
• Choosing an antibiotic for treating GAS pharyngitis necessitates considering factors such as efficacy, safety, antimicrobial spectrum, dosing schedule, therapy compliance, and cost
• Penicillin V is the treatment of choice due to its proven efficacy, safety, and low cost
• Amoxicillin is a suitable alternative, especially for children, considering taste acceptance
• First-generation cephalosporins can be considered as an alternative for individuals with mild penicillin allergies
• For individuals with a penicillin allergy, alternative antibiotics are recommended, including clarithromycin, azithromycin, and clindamycin
• Following antibiotic treatment, symptoms often improve within one to three days
• Returning to work or school is feasible after 24 hours of treatment
• Completion of the full antibiotic course is crucial to prevent complications