From the Guidelines
Doxycycline can be discontinued in this patient with severe foot cellulitis and fever, as the wound culture revealed only methicillin-sensitive Staphylococcus aureus (MSSA) and Group A Streptococcus, both of which are sensitive to piperacillin-tazobactam (pip-tazo). The initial empiric therapy with both antibiotics was reasonable before culture results were available, as severe cellulitis with fever could be caused by a variety of pathogens including resistant organisms, as noted in the guidelines for the diagnosis and management of skin and soft tissue infections 1. Doxycycline is particularly useful for CA-MRSA coverage and has good tissue penetration for skin infections, but once culture results confirm susceptible organisms covered by pip-tazo, antimicrobial stewardship principles suggest narrowing therapy to reduce the risk of adverse effects, prevent development of resistance, and minimize disruption to the patient's normal flora 1. The duration of pip-tazo therapy should typically be 5 days, but treatment should be extended if the infection has not improved within this time period, as recommended by the Infectious Diseases Society of America 1. Some key points to consider in the management of skin and soft tissue infections include:
- Cultures of blood or cutaneous aspirates, biopsies, or swabs are not routinely recommended, but may be considered in certain cases 1
- Hospitalization and empiric antibacterial therapy with vancomycin plus antipseudomonal antibiotics such as cefepime, a carbapenem, or piperacillin-tazobactam are recommended for severe infections 1
- The recommended duration of antimicrobial therapy is 5 days, but treatment should be extended if the infection has not improved within this time period 1
- Elevation of the affected area and treatment of predisposing factors, such as edema or underlying cutaneous disorders, are recommended 1
- Outpatient therapy is recommended for patients who do not have SIRS, altered mental status, or hemodynamic instability 1.
From the Research
Rationale for Adding Doxycycline to Piperacillin-Tazobactam
- The addition of doxycycline to piperacillin-tazobactam in a patient with severe foot cellulitis and fever, given a wound culture positive for pan-sensitive Methicillin-Sensitive Staphylococcus aureus (MSSA) and Group A Streptococcus, may not be directly supported by the provided studies 2, 3, 4, 5, 6.
- Piperacillin-tazobactam has been shown to be effective against a broad spectrum of bacteria, including MSSA and Group A Streptococcus 2, 3, 6.
- However, the use of doxycycline in combination with piperacillin-tazobactam is not explicitly mentioned in the provided studies as a recommended treatment for severe foot cellulitis and fever due to MSSA and Group A Streptococcus.
- One study suggests that piperacillin-tazobactam may not be as effective as other antibiotics, such as nafcillin or oxacillin, in the treatment of MSSA bacteremia 5.
- Another study evaluated the clinical and microbiological effects of a locally delivered antibiotic gel containing piperacillin plus tazobactam compared to a slow-release doxycycline gel, but this was in the context of periodontitis treatment, not severe foot cellulitis and fever 4.
Potential Benefits and Drawbacks
- The addition of doxycycline to piperacillin-tazobactam may provide broader coverage against certain bacteria, but this is not explicitly supported by the provided studies.
- The use of doxycycline in combination with piperacillin-tazobactam may increase the risk of adverse reactions, such as gastrointestinal symptoms and skin reactions, although this is not directly addressed in the provided studies 2, 6.
- The decision to add doxycycline to piperacillin-tazobactam should be based on clinical judgment and consideration of the individual patient's needs and circumstances, as the provided studies do not provide clear guidance on this specific scenario.