From the Research
Yes, the IV cefazolin (Ancef) dose should be increased from the standard 2g IV q8h for skin and soft tissue infection (SSTI) in a 170 kg patient. For patients weighing more than 120 kg, the recommended dose is 3g IV every 8 hours 1. This higher dosage is necessary because drug distribution and clearance are affected by the increased body mass, potentially leading to subtherapeutic concentrations with standard dosing. Inadequate antibiotic concentrations may result in treatment failure and potentially contribute to antibiotic resistance. The increased dose ensures that sufficient antibiotic concentrations reach the infection site to effectively kill the bacteria. Additionally, renal function should be assessed, as dosage adjustments may be needed if the patient has impaired kidney function. The duration of therapy typically ranges from 5-14 days depending on the severity of infection, response to treatment, and whether the infection involves deeper tissues or has systemic manifestations. Some key points to consider when treating SSTIs include:
- The most common pathogens causing SSTIs are Staphylococcus aureus and beta-hemolytic streptococcus 2
- Empiric antibiotic choice should cover these organisms, with consideration for methicillin-resistant Staphylococcus aureus (MRSA) 3
- Vancomycin has been a mainstay of treatment for MRSA infections, but its use has been questioned due to concerns about efficacy and pharmacokinetics 4
- Newer antibiotics, such as linezolid, have been shown to be effective in treating SSTIs, including those caused by MRSA 5, 1
- The choice of antibiotic should be guided by local resistance patterns, patient comorbidities, and the severity of the infection. It is essential to note that the provided evidence does not directly address the dosing of cefazolin in obese patients, but the general principle of adjusting antibiotic doses based on body weight is well-established in clinical practice. Therefore, increasing the IV cefazolin dose to 3g IV every 8 hours in a 170 kg patient with SSTI is a reasonable approach, considering the potential for altered drug distribution and clearance in obese individuals.