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Medline ® Abstracts for References 64,65

of 'Treatment of community-acquired pneumonia in adults who require hospitalization'

64
TI
Polymorphonuclear leukocytes mediate Staphylococcus aureus Panton-Valentine leukocidin-induced lung inflammation and injury.
AU
Diep BA, Chan L, Tattevin P, Kajikawa O, Martin TR, Basuino L, Mai TT, Marbach H, Braughton KR, Whitney AR, Gardner DJ, Fan X, Tseng CW, Liu GY, Badiou C, Etienne J, Lina G, Matthay MA, DeLeo FR, Chambers HF
SO
Proc Natl Acad Sci U S A. 2010;107(12):5587. Epub 2010 Mar 15.
 
Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) is epidemic in the United States, even rivaling HIV/AIDS in its public health impact. The pandemic clone USA300, like other CA-MRSA strains, expresses Panton-Valentine leukocidin (PVL), a pore-forming toxin that targets polymorphonuclear leukocytes (PMNs). PVL is thought to play a key role in the pathogenesis of necrotizing pneumonia, but data from rodent infection models are inconclusive. Rodent PMNs are less susceptible than human PMNs to PVL-induced cytolysis, whereas rabbit PMNs, like those of humans, are highly susceptible to PVL-induced cytolysis. This difference in target cell susceptibility could affect results of experimental models. Therefore, we developed a rabbit model of necrotizing pneumonia to compare the virulence of a USA300 wild-type strain with that of isogenic PVL-deletion mutant and -complemented strains. PVL enhanced the capacity of USA300 to cause severe lung necrosis, pulmonary edema, alveolar hemorrhage, hemoptysis, and death, hallmark clinical features of fatal human necrotizing pneumonia. Purified PVL instilled directly into the lung caused lung inflammation and injury by recruiting and lysing PMNs, which damage the lung by releasing cytotoxic granule contents. These findings provide insights into the mechanism of PVL-induced lung injury and inflammation and demonstrate the utility of the rabbit for studying PVL-mediated pathogenesis.
AD
Division of Infectious Diseases, Department of Medicine, University of California, San Francisco, CA 94110, USA. bdiep@medsfgh.ucsf.edu
PMID
65
TI
Panton-Valentine leukocidin is not a virulence determinant in murine models of community-associated methicillin-resistant Staphylococcus aureus disease.
AU
Bubeck Wardenburg J, Palazzolo-Ballance AM, Otto M, Schneewind O, DeLeo FR
SO
J Infect Dis. 2008;198(8):1166.
 
Increases in the incidence and severity of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) infections have spawned efforts to define unique virulence properties among prevalent strains. Panton-Valentine leukocidin (PVL), a pore-forming cytotoxin, has garnered attention because of its epidemiologic association with CA-MRSA. Using both the clinical isolate LAC, which is representative of the epidemic USA300 strain, and its isogenic PVL-negative strain in murine models of staphylococcal skin infection and pneumonia, we expanded upon recent studies by assessing the contribution of PVL in the genetic background of BALB/c mice. The data presented in this report support the observation that PVL does not contribute to the pathogenesis of staphylococcal infection of mice.
AD
Department of Microbiology, University of Chicago, Chicago, Illinois, USA.
PMID