Methicillin-resistant Staphylococcus aureus Necrotizing Pneumonia

摘要

To the Editor: Methicillin-resist-ant Staphylococcus aureus (MRSA)strains account for >40 of all hospi-tal-acquired S. aureus infections inItaly (1). Although cases of communi-ty-acquired MRSA (CA-MRSA)infections have been reported inrecent years (2), these isolates havenot been characterized for Panton-Valentine leukocidin (PVL) (3); there-fore, the presence of isolates with thetypical characteristics of CA-MRSA(4) in Italy remains unknown. At the beginning of April 2005, a37-year-old woman was admitted tothe University Hospital Policlinico inRome because of fever, cough, andheadache. Her medical history wasunremarkable. She was a teacher in aschool for foreign students in Rome,smoked 3 cigarettes per day for 15years, and reported no recent travelabroad. Her 5-year-old daughter hadinfluenzalike symptoms in the previ-ous week. At hospital admission, hertemperature was 39°C, heart rate was108 beats/min, respiratory rate was 32breaths/min, and blood pressure was105/70 mmHg. Arterial blood gasanalysis showed mild hypoxemia andhypocapnia (PaO273 mm Hg andPaCO234 mm Hg on room air).Leukocyte count was 24,360 cells/μL(81 polymorphonuclear cells), andplatelet count was 506,000/μL. Chestradiograph showed infiltrates in theright upper and lower lobes and leftlower lobe. Empiric treatment withclarithromycin and ceftriaxone wasstarted, but the patient's clinical con-ditions did not improve. Culture ofsputum samples obtained at admis-sion yielded growth of MRSA.Computed tomographic scan showedmultiple lung cavitary lesions, indi-cating necrotizing pneumonia. On day3 of admission, antimicrobial drugtherapy was changed to linezolid (600mg 3 times a day). Fever resolved,and the patient's condition rapidlyimproved. The patient was dischargedafter 14 days of linezolid treatment.At discharge, leukocyte count was6,040 cell/μL (58 polymorphonu-clear cells), and arterial blood gasanalysis showed PaO2of 88 mm