What antibiotic therapy is recommended for a wound culture showing heavy growth of Staphylococcus aureus and Klebsiella pneumoniae?

From the Guidelines

For a wound infection with heavy growth of both Staphylococcus aureus and Klebsiella pneumoniae, a combination antibiotic therapy is recommended, prioritizing coverage for both organisms to minimize morbidity, mortality, and improve quality of life. The optimal regimen would include intravenous antibiotics that provide broad-spectrum coverage, considering the potential for antibiotic resistance. Given the susceptibility results, piperacillin-tazobactam or meropenem would be appropriate choices for covering Klebsiella pneumoniae, while vancomycin or an alternative agent with activity against Staphylococcus aureus, such as ceftaroline, would be necessary for MRSA coverage 1. The choice between these options should be guided by local resistance patterns, patient-specific factors, and the severity of the infection. Treatment duration typically ranges from 7-14 days depending on clinical response, wound characteristics, and patient factors, as suggested by the 2012 Infectious Diseases Society of America clinical practice guideline for the diagnosis and treatment of diabetic foot infections 1. Once culture sensitivities return, therapy should be narrowed to the most appropriate antibiotics to minimize the risk of adverse effects and promote antibiotic stewardship. Adequate wound care, including debridement of necrotic tissue, proper dressing changes, and assessment for adequate blood supply, are equally important components of treatment. In patients with less severe infections or after initial improvement, oral step-down therapy might include trimethoprim-sulfamethoxazole or doxycycline (for MRSA coverage) plus ciprofloxacin or levofloxacin (for Klebsiella coverage), based on susceptibility results.

Key considerations in selecting an antibiotic regimen include:

• The severity of the infection
• The likely etiologic agents
• Local resistance patterns
• Patient-specific factors such as history of MRSA infection or recent antibiotic use
• The need for empiric coverage of gram-negative bacilli and MRSA in severe infections or when risk factors are present, as outlined in the guideline 1.

By prioritizing evidence-based antibiotic therapy and comprehensive wound care, clinicians can optimize outcomes for patients with complex wound infections, reducing the risk of morbidity, mortality, and improving quality of life.

From the FDA Drug Label

Piperacillin and tazobactam for injection, USP is indicated in adults for the treatment of uncomplicated and complicated skin and skin structure infections, including cellulitis, cutaneous abscesses and ischemic/diabetic foot infections caused by beta-lactamase producing isolates of Staphylococcus aureus. Piperacillin and tazobactam for injection, USP is indicated in adults and pediatric patients (2 months of age and older) for the treatment of nosocomial pneumonia (moderate to severe) caused by beta-lactamase producing isolates of Staphylococcus aureus and by piperacillin and tazobactam-susceptible Acinetobacter baumannii, Haemophilus influenzae, Klebsiella pneumoniae, and Pseudomonas aeruginosa

Recommended Antibiotic Therapy:

• Piperacillin/Tazobactam is recommended for the treatment of skin and skin structure infections caused by Staphylococcus aureus and Klebsiella pneumoniae, as it is effective against both organisms 2.
• The choice of antibiotic therapy should be based on culture and susceptibility information, and local epidemiology and susceptibility patterns should be considered in the empiric selection of therapy.
• It is essential to note that the treatment should be used only to treat or prevent infections that are proven or strongly suspected to be caused by bacteria.

From the Research

Antibiotic Therapy for Wound Culture

• The wound culture shows heavy growth of Staphylococcus aureus and Klebsiella pneumoniae, indicating a polymicrobial infection.
• According to the study 3, Staphylococcus aureus is the most common bacteria causing purulent skin and soft tissue infections, and empiric therapy should cover methicillin-resistant S aureus.
• The study 4 compared ceftriaxone and cefazolin for the treatment of methicillin-susceptible Staphylococcus aureus bacteraemia and found no difference in clinical cure rates between the two groups.
• The study 5 found that ceftriaxone is a consideration for definitive therapy of methicillin-susceptible Staphylococcus aureus infection, with a lower risk of toxicity compared to antistaphylococcal antibiotics.
• The study 6 documented the spectrum of activity of ceftaroline against pathogens associated with community-acquired pneumonia, including Staphylococcus aureus and Klebsiella pneumoniae.
• The study 7 found that combination therapy with daptomycin and ceftaroline may be effective for complicated methicillin-resistant Staphylococcus aureus bacteraemia.

Recommended Antibiotic Therapy

• Based on the susceptibility results, ceftaroline may be a suitable option for the treatment of Staphylococcus aureus, as it has shown potent activity against this pathogen 6.
• For Klebsiella pneumoniae, ceftriaxone or ceftazidime may be considered, as they have shown similar potency to ceftaroline against this pathogen 6.
• However, the final antibiotic therapy should be determined based on the patient's clinical condition, local susceptibility patterns, and drug-related safety, tolerability, and cost, as recommended by the study 3.

Considerations

• The use of rifampin should not be used alone for antimicrobial therapy, as recommended by the study results.
• Organisms that are susceptible to tetracycline are also considered susceptible to doxycycline and minocycline.
• More than 90% of S aureus are resistant to penicillin in the United States, thus routine testing is not always indicated for penicillins 3.