Severe influenza and S. aureus pneumonia

EditoriaL 666 Virulence Volume 4 issue 8 Influenza virus is a small virus with a negative stranded segmented RNA genome that causes infections of the respiratory tract in many species, commonly known as " the flu ". 1 The clinical spectrum of influenza infection ranges from a self-limited febrile respiratory illness to severe outcomes, including respiratory failure and death. 2 On average from 1976 to 2009 in the US alone, approximately 66 000 deaths annually were attributed to combined categories of influenza and pneumonia. 3 Several lines of evidence emphasize the central role of bacterial coinfec-tion in severe and fatal cases. The 2009 pandemic influenza A (H1N1) virus resulted in an estimated 284 000 deaths worldwide. 3 Bacterial coinfections complicated up to one-third of pandemic influenza cases managed in the intensive care units and more than 50% of fatal cases. Patients at highest risk for severe complications of influenza included children under the age of 5 years, adults 65 years of age or older, children and adults of any age with underlying chronic medical conditions, and pregnant women. 3 In a large series of critically ill children with the 2009 pandemic influenza strain, 8 33% had evidence of bacterial confection within 72 h of admission. S. aureus was the most common pathogen accounting for 39% of isolates from respiratory cultures. Among S. aureus isolates 58% were methicillin-resistant (MRSA). The 2009 pandemic of the new influenza A strain H1N1 highlighted several public health concerns: (1) While vaccination against influenza still remains the most effective means of preventing bacterial co-infections, the ever-changing nature of the circulating influenza viruses pose a major challenge in generating protective vaccines every year; (2) The number of immu-nocompromised individuals is increasing due to our aging society and improved survival of patients with underlying medical conditions: these individuals may not develop protective immunity in response to influenza vaccine; (3) The efficacy of antiviral therapy for the treatment of influenza infection is dependent on susceptibility of circulating influenza strain to available antivi-ral medication; and (4) S. aureus colonizes the nares of up to 30% of adult population. 9 Factors implicated in the increased prevalence of S. aureus colonization include but are not limited to pneumococcal vaccination, ecosystem degradation due to effects of widespread antibiotic use on the nasopharyngeal and cutane-ous microbiota or a combination of these factors. Over the past 10 years, methicillin-resistant S. aureus (MRSA) has become a …