Methicillin resistant Staphylococcus aureus necrotizing pneumonia and ceftaroline fosamil: An alternative regimen

Abstract

Introduction: Pneumonia is defined as an infection of the parenchyma of the lung and is one of the most common causes of death from infectious diseases in the United States (US). Pneumonia is classified into two groups; community acquired pneumonia (CAP) and hospital acquired pneumonia (HAP). Most CAPs are secondary to bacterial pathogens. Methicillin resistant Staphylococcus aureus (MRSA) is identified as a potential pathogen in 8.9% of CAP cases. Community acquired methicillin resistant Staphylococcus aureus (CA-MRSA) produces a cytotoxin called Panton–Valentine leukocidin (PVL), which causes white blood cell destruction and necrosis, resulting in necrotizing pneumonia when it reaches the lungs. Vancomycin and linezolid are most common recommended antibiotics when treating MRSA necrotizing pneumonia. Ceftaroline fosamil, a fifth-generation cephalosporin, is approved for the treatment of skin and soft tissue infection caused by MRSA and pneumonia, but it has not been approved for MRSA pneumonia. Case Report: A 72-year-old Hispanic male presented with a medical history of hypertension, diabetes mellitus type 2, chronic kidney disease stage 3B, unspecified chronic thrombocytopenia and asthma developed an upper respiratory tract infection that manifested with fever and rhinorrhea and resolved without treatment. Ten days later, the patient arrived at the emergency room due to productive cough of rust colored sputum that started three days before admission. Associated symptoms included malaise, fever, chills and shortness of breath. The patient was admitted to medicine ward with diagnosis of CAP and was initially managed with azithromycin/ceftriaxone. However, persistent fever and tachypnea resulted in the need for reassessment. Sputum culture revealed MRSA and the patient was switched to ceftaroline fosamil for a 21-day course of treatment. Patient was discharged home and has been followed at the outpatient clinic with none of the aforementioned symptoms. Conclusion: Methicillin resistant Staphylococcus aureus necrotizing pneumonia is an uncommon cause of CAP, but its incidence has increased during the recent years. This type of CAP has gained notoriety due to the PVL cytotoxin, with its dire results. Vancomycin and linezolid are the most recommended antibiotics; vancomycin is recommended if the bacteria show a minimum inhibitory concentration (MIC) < 2. In this case, the S. aureus recovered at sputum culture showed a MIC >2 and since the patient presented with several additional comorbidities management was started with ceftaroline fosamil, a fifth-generation cephalosporin that has no hepatic adjustment and has no problem in thrombocytopenic patients. The ceftaroline fosamil was administered at 400 mg intravenously every 12 hours for 21 days. The patient improved clinically and was discharged home and followed the next week then monthly for two months.