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Abstract

Introduction: Panton-Valentine Leukocidin (PVL) is one of the virulence factors expressed by Staphylococcus aureus. Numerous cases of necrotizing pneumonia due to PVL positive Methicilllin Resistant Staphylococcus Aureus (MRSA) have been reported which start with influenza like symptoms and result in death. We present a case of PVL positive Staphylococcus aureus necrotizing pneumonia and multi-organ failure successfully treated with antibiotics and lung protective strategies. Case Description: A thirty nine years old previously healthy woman presented to her primary care doctor with upper respiratory tract symptoms. Her nasal swab was positive for influenza A and she was started on Tamiflu therapy. On the fourth day of anti-viral treatment she presented to emergency department with worsening respiratory symptoms and profound hypoxia. She required immediate endo-tracheal intubation and mechanical ventilation secondary to hypoxia and signs of multisystem organ dysfunction. She had fever, marked lymphopenia and chest radiograph revealing bilateral pneumonia. The emergency department provider initiated guideline driven antibiotics for community acquired pneumonia. On evaluation by the treating intensivist, and with recognition of her history of present illness, additional antibiotics targeted specifically at community acquired MRSA and its toxemia were prescribed. Her multisystem organ failure continued to worsen secondary to her MRSA septic shock and destructive necrotizing pneumonia with associated pneumothorax. She was maintained on both intravenous linezolid and clindamycin for bactericidal and anti-toxin effects. Her ventilation was supported on Airway Pressure Release Ventilation (APRV) mode for hypoxic respiratory failure and lung protective benefits. Unfortunately she required continuous renal replacement therapy (CRRT) for acute renal failure (ARF). ARF was associated with her shock and intentional judicious use of fluid resuscitation to avoid detrimental non-cardiogenic pulmonary edema effects. Her hospital course was further complicated by critical illness myopathy, immune mediated encephalomyelitis, and chronic critical illness. Our state laboratory confirmed presence of PVL MRSA bacteremia. After two months of hospitalization she was discharged to a rehabilitation center. Discussion: PVL is a cytotoxin that causes leukocyte destruction and tissue necrosis. PVL positive MRSA has a propensity for rapidly establishing in the lung producing leukocidin which causes necrotizing vasculitis with massive pulmonary hemorrhage resulting in necrotizing pneumonia. Studies have shown up to 75% mortality rate in patient with necrotizing pneumonia due to PVL positive MRSA. It usually occurs in otherwise healthy young people preceded by viral influenza. Initial management includes broad spectrum antibiotics which inhibit toxin production and kill the bacteria. Further lung injury should be prevented with lung protective mechanical ventilation and judicious fluid resuscitation in accordance with ARDSNet data. Case reports have discussed potential benefits of plasmapheresis, intravenous immunoglobulin and activated protein C if available. The early recognition and diagnosis of PVL MRSA pneumonia leading to appropriate antibiotic therapy are the cornerstones of treating this deadly necrotizing pneumonia. Multidisciplinary intensivist driven care and lung protective strategies provide needed care in these complex cases. There should be a high index of suspicion if healthy young patients present with acute respiratory failure after influenza infection.