Is Keflex (Cephalexin) 1000 mg BID for 10 days an appropriate treatment for a patient with moderate growth of Staphylococcus aureus from a wound culture?

From the Guidelines

Keflex (Cephalexin) 1000 mg BID for 10 days is not the most appropriate treatment for a patient with moderate growth of Staphylococcus aureus from a wound culture, as the recommended dosage for adults is 500 mg qid po or 25–50 mg/kg/d in 4 divided doses po, according to the IDSA practice guidelines 1. The patient's treatment should be based on the most recent and highest quality evidence available. In this case, the IDSA practice guidelines from 2014 provide recommendations for the treatment of skin and soft tissue infections, including those caused by Staphylococcus aureus 1. Some key points to consider when treating a patient with a wound culture showing moderate growth of Staphylococcus aureus include:

• The decision to administer antibiotics should be based on the presence or absence of systemic inflammatory response syndrome (SIRS) and the patient's overall clinical condition 1.
• The recommended antibiotic regimen should be active against methicillin-susceptible Staphylococcus aureus (MSSA) or methicillin-resistant Staphylococcus aureus (MRSA), depending on the susceptibility results from the culture 1.
• The patient should be monitored for signs of worsening infection, such as increased redness, swelling, pain, or fever, which might indicate treatment failure or development of resistance 1.
• Wound care, including regular cleaning and dressing changes, should accompany antibiotic therapy to promote healing and prevent further infection 1. It is essential to note that the patient's specific clinical condition, including the presence of any underlying medical conditions or allergies, should be taken into account when selecting an antibiotic regimen. In this case, considering the patient's wound culture shows moderate growth of Staphylococcus aureus, a more appropriate treatment would be Cephalexin 500 mg qid po or 25–50 mg/kg/d in 4 divided doses po, as recommended by the IDSA practice guidelines 1.

From the FDA Drug Label

The usual adult dose is 250 mg every 6 hours For the following infections, a dosage of 500 mg may be administered every 12 hours: streptococcal pharyngitis, skin and skin structure infections, and uncomplicated cystitis in patients over 15 years of age. For more severe infections or those caused by less susceptible organisms, larger doses may be needed

The prescribed dose of Keflex (Cephalexin) 1000 mg BID for 10 days is higher than the usual recommended dose for skin and skin structure infections. However, it is within the recommended daily dosage range of 1 to 4 g. Given that the patient has a moderate growth of Staphylococcus aureus, which may be considered a more severe infection, a larger dose may be needed. Therefore, the prescribed treatment of Keflex 1000 mg BID for 10 days may be appropriate for this patient 2.

• Key points:
  • The patient has a moderate growth of Staphylococcus aureus
  • The prescribed dose is within the recommended daily dosage range
  • The prescribed dose may be appropriate for a more severe infection
  • The treatment duration is 10 days, which is within the recommended range for cystitis therapy (7 to 14 days) but may need to be adjusted based on the specific infection and patient response.

From the Research

Treatment of Staphylococcus aureus Infections

• The patient has a wound culture showing moderate growth of Staphylococcus aureus, and the treatment prescribed is Keflex (Cephalexin) 1000 mg BID for 10 days 3.
• Cephalexin is used for the treatment of methicillin-susceptible Staphylococcus aureus (MSSA) infections, which is likely the case here since the susceptibility results are not mentioned 4, 5.
• The dosage of 1000 mg BID is within the range of proposed dosing regimens for MSSA infections, although the exact dosage may depend on the minimum inhibitory concentration (MIC) of the bacteria 3.

Comparison of Treatment Options

• Antistaphylococcal penicillins (ASPs) and cephalosporins, such as cephalexin, are commonly used for the treatment of MSSA infections 5.
• A systematic review and meta-analysis found no statistically significant difference in mortality between ASPs and cephalosporins for the treatment of MSSA bacteraemia 5.
• However, the choice of antibiotic may depend on various factors, including the severity of the infection, patient comorbidities, and local resistance patterns 4, 6.

Duration and Follow-up of Treatment

• The prescribed treatment duration of 10 days may be sufficient for uncomplicated skin and soft tissue infections, but the duration of treatment may need to be adjusted based on the patient's response and the severity of the infection 7.
• Follow-up in two weeks is reasonable to assess the patient's response to treatment and to adjust the treatment plan as needed 7.