title: Fatal Fulminant Pneumonia Caused by Methicillin-Sensitive Staphylococcus aureus Negative for Major High-Virulence Factors Following Influenza B Virus Infection.
abstract: BACKGROUND
  Increasing evidence has indicated that Staphylococcus aureus pneumonia complicated with influenza virus infection is often fatal. In these cases, disease severity is typically determined by susceptibility to antimicrobial agents and the presence of high-virulence factors that are produced by Staphylococcus aureus, such as Panton-Valentine leukocidin (PVL).
  
  
  METHODS
  We describe a rare case of fatal community-acquired pneumonia caused by methicillin-sensitive Staphylococcus aureus (MSSA), which did not secrete major high-virulence factors and coexisted with influenza type B infection. The 32-year-old previously healthy male patient presented with dyspnea, high fever, and cough. His roommate had been diagnosed with influenza B virus infection 3 days earlier. Gram-positive clusters of cocci were detected in the patient's sputum; therefore, he was diagnosed with severe pneumonia and septic shock, and was admitted to the intensive care unit. Despite intensive antibiotic and antiviral treatment, he died of multiple organ failure 5 days after admission. His blood culture from the admission was positive for MSSA, and further analysis revealed that the strain was negative for major high-virulence factors, including PVL and enterotoxins, although influenza B virus RNA was detected by PCR.
  
  
  CONCLUSIONS
  Physicians should pay special attention to patients with pneumonia following influenza and Staphylococcus aureus infection, as it may be fatal, even if the Staphylococcus aureus strain is PVL-negative and sensitive to antimicrobial agents.
authors.affiliation: Division of Pulmonary Medicine, Department of Medicine, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Katsunori
authors.initials: K
authors.lastname: Masaki
authors.affiliation: Division of Pulmonary Medicine, Department of Medicine, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Ishii
authors.affiliation: Division of General Thoracic Surgery, Department of Surgery, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Anraku
authors.affiliation: Division of Pulmonary Medicine, Department of Medicine, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Ho
authors.initials: H
authors.lastname: Namkoong
authors.affiliation: Division of Pulmonary Medicine, Department of Medicine, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Miyakawa
authors.affiliation: Division of Pulmonary Medicine, Department of Medicine, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Nakajima
authors.affiliation: Division of Pulmonary Medicine, Department of Medicine, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Koichi
authors.initials: K
authors.lastname: Fukunaga
authors.affiliation: Division of Pulmonary Medicine, Department of Medicine, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Naoki
authors.affiliation: Division of Pulmonary Medicine, Department of Medicine, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Sadatomo
authors.initials: S
authors.lastname: Tasaka
authors.affiliation: Division of Pulmonary Medicine, Department of Medicine, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Kenzo
authors.initials: K
authors.lastname: Soejima
authors.affiliation: Division of Pulmonary Medicine, Department of Medicine, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Koichi
authors.initials: K
authors.lastname: Sayama
authors.affiliation: Center for Infectious Diseases and Infection Control, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Kayoko
authors.initials: K
authors.lastname: Sugita
authors.affiliation: Center for Infectious Diseases and Infection Control, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Iwata
authors.affiliation: Research Center for Infections and Antimicrobials, Kitasato Institute for Life Sciences, Kitasato University, Tokyo, Japan.
authors.forename: Longzhu
authors.initials: L
authors.lastname: Cui
authors.affiliation: Research Center for Infections and Antimicrobials, Kitasato Institute for Life Sciences, Kitasato University, Tokyo, Japan.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Hanaki
authors.affiliation: Center for Infectious Diseases and Infection Control, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Hasegawa
authors.affiliation: Division of Pulmonary Medicine, Department of Medicine, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Betsuyaku
mesh_terms: D000328:Adult; D017809:Fatal Outcome; D006801:Humans; D009981:Influenza B virus / Q000302:isolation & purification*; D007251:Influenza, Human / Q000150:complications* / Q000175:diagnosis / Q000821:virology; D008297:Male; D016106:Methicillin Resistance; D011023:Pneumonia, Staphylococcal / Q000188:drug therapy / Q000209:etiology / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000302:isolation & purification*; D037521:Virulence Factors
chemical_list: D037521:Virulence Factors