title: Inability of polymerase chain reaction, pyrosequencing, and culture of infected and uninfected site skin biopsy specimens to identify the cause of cellulitis.
abstract: BACKGROUND
  The cause of cellulitis is unclear. Streptococcus pyogenes, and to a lesser extent, Staphylococcus aureus, are presumed pathogens.
  
  
  METHODS
  We conducted a study of adults with acute cellulitis without drainage presenting to a US emergency department research network. Skin biopsy specimens were taken from the infected site and a comparable uninfected site on the opposite side of the body. Microbiology was evaluated using quantitative polymerase chain reaction (PCR), pyrosequencing, and standard culture techniques. To determine the cause, the prevalence and quantity of bacterial species at the infected and uninfected sites were compared.
  
  
  RESULTS
  Among 50 subjects with biopsy specimens from infected and uninfected sites, culture rarely identified a bacterium. Among 49 subjects with paired specimens from infected and uninfected sites tested with PCR, methicillin-susceptible S. aureus was identified in 20 (41%) and 17 (34%), respectively. Pyrosequencing identified abundant atypical bacteria in addition to streptococci and staphylococci. Among 49 subjects with paired specimens tested by pyrosequencing, S. aureus was identified from 11 (22%) and 15 (31%) and streptococci from 15 (31%) and 20 (41%) of the specimens, respectively. Methicillin-resistant S. aureus was not found by culture or PCR, and S. pyogenes was not identified by any technique.
  
  
  CONCLUSIONS
  The bacterial cause of cellulitis cannot be determined by comparing the prevalence and quantity of pathogens from infected and uninfected skin biopsy specimens using current molecular techniques. Methicillin-susceptible S. aureus was detected but not methicillin-resistant S. aureus or S. pyogenes from cellulitis tissue specimens. For now, optimal treatment will need to be guided by clinical trials. Noninfectious causes should also be explored.
authors.affiliation: Departments of Emergency Medicine.
authors.forename: Jonathan G
authors.initials: JG
authors.lastname: Crisp
authors.affiliation: Departments of Emergency Medicine and Medicine, Division of Infectious Diseases, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts.
authors.forename: Sukhjit S
authors.initials: SS
authors.lastname: Takhar
authors.affiliation: Departments of Emergency Medicine Department of Medicine, Division of Infectious Diseases, Olive View-UCLA Medical Center.
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: Moran
authors.affiliation: Departments of Emergency Medicine.
authors.forename: Anusha
authors.initials: A
authors.lastname: Krishnadasan
authors.affiliation: MR DNA, Shallowater, Texas.
authors.forename: Scot E
authors.initials: SE
authors.lastname: Dowd
authors.affiliation: Department of Medicine, Division of Infectious Diseases, VA Greater Los Angeles Healthcare System, The David Geffen School of Medicine at UCLA, Los Angeles, California.
authors.forename: Sydney M
authors.initials: SM
authors.lastname: Finegold
authors.affiliation: Department of Medicine, Division of Infectious Diseases, VA Greater Los Angeles Healthcare System, The David Geffen School of Medicine at UCLA, Los Angeles, California.
authors.forename: Paula H
authors.initials: PH
authors.lastname: Summanen
authors.affiliation: Departments of Emergency Medicine Department of Medicine, Division of Infectious Diseases, Olive View-UCLA Medical Center.
authors.forename: David A
authors.initials: DA
authors.lastname: Talan
mesh_terms: D000328:Adult; D000368:Aged; D001419:Bacteria / Q000235:genetics / Q000302:isolation & purification*; D001431:Bacteriological Techniques; D001706:Biopsy; D002481:Cellulitis / Q000175:diagnosis* / Q000382:microbiology*; D059014:High-Throughput Nucleotide Sequencing; D006801:Humans; D055624:Methicillin-Resistant Staphylococcus aureus / Q000235:genetics / Q000302:isolation & purification; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D012867:Skin / Q000382:microbiology*; D013203:Staphylococcal Infections / Q000175:diagnosis; D013211:Staphylococcus aureus / Q000235:genetics / Q000302:isolation & purification; D013290:Streptococcal Infections / Q000175:diagnosis; D013297:Streptococcus pyogenes / Q000235:genetics / Q000302:isolation & purification; D055815:Young Adult
keywords: PCR; cellulitis; culture; polymerase chain reaction; pyrosequencing