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AI-Generated response:

Why is Penicillin V preferred to Amoxicillin in treatment of Strep pharyngitis?

Answer generated on June 4, 2024

The AI-generated responses are for illustration purposes only and should not be used for medical purposes.

Penicillin V is preferred to Amoxicillin in the treatment of streptococcal pharyngitis primarily due to its proven efficacy, cost-effectiveness, and narrow spectrum of activity, which minimizes the risk of developing antibiotic resistance.[1-3]

  • Penicillin V has a long-standing record of effectiveness in treating streptococcal pharyngitis and preventing rheumatic fever, which is crucial in managing the disease.[1-2]

  • It is cost-effective compared to many other antibiotics, making it a practical choice for widespread use in clinical settings.[2]

  • Penicillin V has a narrow spectrum of activity, which helps in minimizing the development of resistance among bacteria, an important consideration in antibiotic stewardship.[1-2]

  • The drug is typically administered in a 10-day regimen, which has been shown to be effective in eradicating the infection and preventing complications such as rheumatic fever.[2-3]

  • While Amoxicillin is also effective and may be preferred for children due to better taste and once-daily dosing, Penicillin V remains the standard due to its narrow spectrum and cost benefits.[4]

Additional info

The choice between Penicillin V and Amoxicillin for streptococcal pharyngitis also considers patient compliance and the potential for allergic reactions. Penicillin V, being a narrow-spectrum antibiotic, is less likely to alter the normal bacterial flora significantly, thereby reducing the risk of secondary infections or complications. Amoxicillin, while convenient due to less frequent dosing, carries a slightly higher risk of allergic reactions and its broader spectrum may impact gut flora more extensively. The decision to use Penicillin V over Amoxicillin is also supported by guidelines that emphasize the importance of targeted therapy to prevent rheumatic fever, a serious complication of streptococcal pharyngitis. In settings where compliance with a 10-day regimen is a concern, alternatives like benzathine penicillin G, which requires only a single dose, might be considered, ensuring that the full course of therapy is completed.[1-2][5] This approach aligns with the principles of antibiotic stewardship, aiming to use the most effective, narrow-spectrum antibiotic to achieve therapeutic goals while minimizing the impact on broader public health.

References

Reference 1

1.

Elsevier ClinicalKey Drug Class Overview

Content last updated: January 1, 2012.

Penicillin V, amoxicillin, or benzathine penicillin G are the drugs of choice for primary prevention of rheumatic fever and for the treatment of streptococcal pharyngitis[49852].

Reference 2

2.

Stevens, Dennis L., Bryant, Amy E., Hagman, Melissa M. (2024). In Goldman-Cecil Medicine (pp. 1913). DOI: 10.1016/B978-0-323-93038-3.00269-0

Trimethoprim-sulfamethoxazole is not active against group A streptococci and therefore should not be used alone for infections in which group A streptococcus is the suspected pathogen. However, trimethoprim-sulfamethoxazole (four single-strength pills, each containing 80mg of trimethoprim and 400 mg of sulfamethoxazole, twice daily for 7 days)is effective for uncomplicated abscesses in whichStaphylococcus aureusis thought to be the primary pathogen andS. pyogenesonly a potential co-pathogen.Specific InfectionsPharyngitisThe acute symptoms of streptococcal pharyngitis usually resolve within 3 to 6 days even without treatment. The goal of treatment is to reduce the incidence of streptococcal sequelae such as suppurative head and neck infections, scarlet fever, bacteremia, and rheumatic fever.For pharyngitis in patients over age 6 years, oral penicillin VK (1000mg three times daily for 10 days or 800 mg four times daily for 5 days)or injectable benzathine penicillin (1.2 million units intramuscularly once) is the treatment of choice because it is cost effective, has a narrow spectrum of activity, and has long-standing proven efficacy (Chapter 397).Cephalexin (500 mg orally twice a day for 5 to 10 days) is also effective for primary treatment and for persistent infection. Patients with proven recurrent infections should receive clindamycin (300mg orally three times a day for 10 days) or amoxicillin–clavulanic acid (875mg orally twice a day, or 500mg three times a day for 10 days).

Reference 3

3.

Elsevier ClinicalKey Clinical Overview

Treatment Treatment of bacterial pharyngitis: CDC recommends laboratory confirmation of group A streptococcal pharyngeal infection before treatment in nearly all patients with pharyngitis (few exceptions) Consider empiric antibiotic treatment of streptococcus pending culture results in the following limited patient populations who have symptoms of pharyngitis that are clinically concerning for acute streptococcal infection: Patients with a history of rheumatic fever Patients who are immunosuppressed Patients who are in close contact with persons with invasive infections (eg, necrotizing fasciitis, streptococcal toxic shock syndrome) Consider in patients during a community outbreak of acute rheumatic fever or poststreptococcal glomerulonephritis In general, treat children and adults who have positive rapid streptococcus antigen test results or positive group A β-hemolytic streptococcus throat cultures for 10 days Give amoxicillin or penicillin V as first line treatment For patients with a non–type I hypersensitivity to penicillin, give cephalexin, cefadroxil, clindamycin, clarithromycin, or azithromycin For patients with an immediate type I hypersensitivity to penicillin, give clindamycin, clarithromycin, or azithromycin Group A streptococci resistant to azithromycin and clindamycin are increasingly common; Consider all patients with streptococcal pharyngitis infectious until they have completed 24 hours of antibiotic therapy Treatment of specific viral pharyngitis: HSV gingivostomatitis Acyclovir given within 72 hours of symptom onset reduces symptom duration if history and physical examination are consistent with HSV gingivostomatitis Influenza

Reference 4

4.

Gigante, Joseph (2025). In Nelson Textbook of Pediatrics (pp. 2558). DOI: 10.1016/B978-0-323-88305-4.00430-2

Antibiotic treatment should not be delayed for children with symptomatic pharyngitis and a positive test for GAS. Presumptive antibiotic treatment can be started when there is a clinical diagnosis of scarlet fever, a symptomatic child has a household contact with documented streptococcal pharyngitis, or there is a history of ARF in the patient or a family member, but a diagnostic test should be performed to confirm the presence of GAS, and antibiotics should be discontinued if GAS is not identified. A variety of antimicrobial agents are effective for GAS pharyngitis (Table 430.4). Group A streptococci are universally susceptible to penicillin and all other β-lactam antibiotics. Penicillin is inexpensive, has a narrow spectrum of activity, and has few adverse effects. Amoxicillin is often preferred for children because of its taste, availability as chewable tablets and liquid, and the convenience of once-daily dosing. The duration of oral penicillin and amoxicillin therapy is 10 days. A single intramuscular dose of benzathine penicillin or a benzathine–procaine penicillin G combination is effective and ensures compliance. Follow-up testing for GAS is unnecessary after completion of therapy and is not recommended unless symptoms recur. Patients allergic to the penicillins can be treated with a 10-day course of a narrow-spectrum, first-generation cephalosporin (cephalexin or cefadroxil) if the previous reaction to penicillin was not an immediate, type I hypersensitivity reaction. Frequently, penicillin-allergic patients are treated for 10 days with erythromycin, clarithromycin, or clindamycin, or for 5 days with azithromycin. The increased use of macrolides and related antibiotics for a variety of infections, especially the azalide azithromycin, is associated with increased rates of resistance to these drugs among GAS in manycountries. Approximately 5% of GAS in the United States and more than 10% in Canada are macrolide-resistant (macrolide resistance includes azalide resistance), but there is considerable local variation in both countries.

Reference 5

5.

Elsevier ClinicalKey Derived Clinical Overview

• Penicillin V 250 mg PO bid-tid (<27 kg) or 500 mg PO bid-tid (>27 kg) for 10 days. Amoxicillin 50 mg/kg once daily (max. 1000 mg/day) for 10 days is an equivocal first-line alternative. For penicillin-allergic patients, may consider clindamycin, azithromycin, or clarithromycin as alternative therapies. First-generation cephalosporins can also be used for patients with a nonanaphylactic penicillin allergy. • Benzathine penicillin 600,000 U (<27 kg) or 1.2 million U (>27 kg) intramuscularly once, whichmay be used for a patient who cannot swallow pills. • A clinical response can be expected in 24 to 48 hr. Of note, patient is typically no longer infectious after 24 hr of antibiotic therapy. note:Failure to respond to penicillin should raise doubt about the diagnosis, sinceStreptococcuscan also be carried in the pharynx without causing infection.

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