Severe community-onset pneumonia in healthy adults caused by methicillin-resistant Staphylococcus aureus carrying the Panton-Valentine leukocidin genes.
BACKGROUND
Recent worldwide reports of community-onset skin abscesses, outbreaks of furunculosis, and severe pneumonia associated with methicillin-resistant Staphylococcus aureus (MRSA) carrying Panton-Valentine leukocidin (PVL) genes and the staphylococcal cassette chromosome mec (SCCmec) type IV indicate that MRSA infections are evolving into a community-related problem. The majority of cases reported to date involve skin and soft-tissue infections, with severe pneumonia representing a relatively rare phenomenon. During a 2-month period in the winter of 2003-2004, four healthy adults presented to 1 of 2 Baltimore hospitals with severe necrotizing MRSA pneumonia in the absence of typical risk factors for MRSA infection.


METHODS
Patients' MRSA isolates were characterized by strain typing with use of pulsed-field gel electrophoresis and SCCmec typing with use of a multiplex polymerase chain reaction (PCR) assay and detection of PVL genes by PCR.


RESULTS
All 4 patients' MRSA isolates carried the PVL genes and the SCCmec type IV element and belonged to the USA300 pulsed-field type. These 3 findings are among the typical characteristics of community-onset MRSA strains. In addition, 2 of our patients had concomitant influenza A diagnosed, which likely contributed to the severity of their presentation.


CONCLUSIONS
To our knowledge, these patients represent the first reported North American adults with severe community-onset MRSA pneumonia caused by strains carrying the PVL genes.
Francis
John S
JS
Division of Infectious Diseases, Department of Medicine, Johns Hopkins Medical Institutions, Baltimore, MD, USA. jfranc13@jhmi.edu
Doherty
Meg C
MC
Lopatin
Uri
U
Johnston
Cecilia P
CP
Sinha
Gita
G
Ross
Tracy
T
Cai
Mian
M
Hansel
Nadia N
NN
Perl
Trish
T
Ticehurst
John R
JR
Carroll
Karen
K
Thomas
David L
DL
Nuermberger
Eric
E
Bartlett
John G
JG
D000328:Adult; D001427:Bacterial Toxins; D015373:Bacterial Typing Techniques; D017714:Community-Acquired Infections / Q000382:microbiology*; D005098:Exotoxins; D005260:Female; D006801:Humans; D007956:Leukocidins / Q000235:genetics*; D008297:Male; D008712:Methicillin / Q000494:pharmacology; D016106:Methicillin Resistance; D008875:Middle Aged; D018579:Patient Selection; D013203:Staphylococcal Infections / Q000453:epidemiology / Q000382:microbiology; D013211:Staphylococcus aureus / Q000145:classification / Q000187:drug effects* / Q000235:genetics / Q000472:pathogenicity; D037521:Virulence Factors / Q000032:analysis
D001427:Bacterial Toxins; D005098:Exotoxins; D007956:Leukocidins; C078284:Panton-Valentine leukocidin; D037521:Virulence Factors; D008712:Methicillin