Does cephalexin (Cefalexin) cover Streptococcus (strep) infections?

From the Guidelines

Cephalexin is an effective antibiotic for treating strep infections, including Group A Streptococcus, and is recommended for individuals with penicillin allergy. According to the 2012 update by the Infectious Diseases Society of America, cephalexin is a suitable alternative for patients allergic to penicillin, with a recommended dosage of 20 mg/kg/dose twice daily (max = 500 mg/dose) for 10 days 1. This guideline emphasizes the importance of accurate diagnosis and appropriate antimicrobial therapy to prevent complications such as acute rheumatic fever and suppurative infections.

Key points to consider when prescribing cephalexin for strep infections include:

• The dosage and duration of treatment, which should be 10 days as recommended by the guideline 1
• The potential for cross-reactivity in patients with penicillin allergies, although this is relatively rare 1
• The importance of completing the full course of antibiotics to ensure the infection is fully eradicated and to prevent complications
• The need for medical supervision and a prescription to prevent antibiotic resistance

It is essential to note that cephalexin is effective against Group A Streptococcus, but it is crucial to establish an accurate diagnosis before initiating treatment, as antimicrobial therapy is of no proven benefit for nonstreptococcal pharyngitis 1.

From the FDA Drug Label

Cephalexin is indicated for the treatment of the following infections when caused by susceptible strains of the designated microorganisms: Respiratory tract infections caused by Streptococcus pneumoniae and Streptococcus pyogenes Cephalexin has been shown to be active against most strains of the following microorganisms both in vitro and in clinical infections as described in the INDICATIONS AND USAGE section Aerobes, Gram-positive: Staphylococcus aureus (including penicillinase-producing strains) Streptococcus pneumoniae (penicillin-susceptible strains) Streptococcus pyogenes

Cephalexin covers strep, specifically Streptococcus pneumoniae and Streptococcus pyogenes, as stated in the indications and usage section of the drug label 2. However, it is essential to note that penicillin is the usual drug of choice in the treatment and prevention of streptococcal infections, including the prophylaxis of rheumatic fever.

• The drug label indicates that cephalexin is generally effective in the eradication of streptococci from the nasopharynx.
• Culture and susceptibility tests should be initiated prior to and during therapy to ensure the bacteria are susceptible to cephalexin 2.
• The MIC values for cephalexin against Streptococcus pneumoniae and Streptococcus pyogenes are not explicitly stated in the provided drug labels, but the labels do provide interpretation criteria for susceptibility testing results 2.

From the Research

Cephalexin Coverage for Strep

• Cephalexin is effective against Group A beta-hemolytic streptococcal (GABHS) infections, including strep throat 3, 4, 5, 6.
• Studies have shown that cephalexin has a higher bacteriologic and clinical cure rate compared to penicillin in the treatment of GABHS pharyngitis 5, 6.
• A meta-analysis of 19 studies found that oral cephalosporins, including cephalexin, had a lower failure rate than oral penicillin in the treatment of GABHS pharyngitis 5.
• Cephalexin has been shown to be effective in treating GABHS tonsillopharyngitis, with a bacteriologic cure rate of 87-92% and a clinical cure rate of 91-95% 4, 6.
• The American Academy of Pediatrics recommends penicillin as the first-line therapy for GABHS infections, but cephalexin is considered a suitable alternative, especially in cases of penicillin treatment failures or allergies 3.

Comparison with Penicillin

• Cephalexin has been compared to penicillin in several studies, with results showing that cephalexin is more effective in treating GABHS infections 5, 6.
• A randomized, double-blind, crossover study found that cephalexin had a lower treatment failure rate than penicillin in children with GABHS tonsillopharyngitis 6.
• Another study found that cephalexin had a higher bacteriologic and clinical cure rate than penicillin in the treatment of GABHS pharyngitis 5.

Dosage and Administration

• Cephalexin can be administered twice or three times daily, with a dosage of 27 mg/kg per day for 10 days 4, 6.
• A 5-day regimen of cephalexin is also possible, although a 10-day course is recommended to optimize cure in GABHS infections 3.