title: Direct molecular versus culture-based assessment of Gram-positive cocci in biopsies of patients with major abscesses and diabetic foot infections.
abstract: Major abscesses and diabetic foot infections (DFIs) are predominant subtypes of complicated skin and skin structure infections (cSSSIs), and are mainly caused by Staphylococcus aureus and β-hemolytic streptococci. This study evaluates the potential benefit of direct pathogen-specific real-time polymerase chain reaction (PCR) assays in the identification of causative organisms of cSSSIs. One-hundred and fifty major abscess and 128 DFI biopsy samples were collected and microbial DNA was extracted by using the Universal Microbe Detection kit for tissue samples. Pathogen-specific PCRs were developed for S. aureus and its virulence factor Panton-Valentine leukocidin (PVL), Streptococcus pyogenes, S. agalactiae, S. dysgalactiae, and the S. anginosus group. Identification by pathogen-specific PCRs was compared to routine culture and both methods were considered as the gold standard for determination of the sensitivity and specificity of each assay. Direct real-time PCR assays of biopsy samples resulted in a 34 % higher detection of S. aureus, 37 % higher detection of S. pyogenes, 18 % higher detection of S. agalactiae, 4 % higher detection of S. dysgalactiae subspecies equisimilis, and 7 % higher detection of the S. anginosus group, compared to routine bacterial culture. The presence of PVL was mainly confined to S. aureus isolated from major abscess but not DFI biopsy samples. In conclusion, our pathogen-specific real-time PCR assays had a higher yield than culture methods and could be an additional method for the detection of relevant causative pathogens in biopsies.
authors.affiliation: Department of Internal Medicine, Radboud University Medical Center, P.O. Box 9101, 6500 HB, Nijmegen, The Netherlands.
authors.forename: M H T
authors.initials: MH
authors.lastname: Stappers
authors.forename: F
authors.initials: F
authors.lastname: Hagen
authors.forename: P
authors.initials: P
authors.lastname: Reimnitz
authors.forename: J W
authors.initials: JW
authors.lastname: Mouton
authors.forename: J F
authors.initials: JF
authors.lastname: Meis
authors.forename: I C
authors.initials: IC
authors.lastname: Gyssens
mesh_terms: D000038:Abscess / Q000175:diagnosis* / Q000382:microbiology; D015373:Bacterial Typing Techniques; D017719:Diabetic Foot / Q000175:diagnosis* / Q000382:microbiology; D006801:Humans; D060888:Real-Time Polymerase Chain Reaction; D013203:Staphylococcal Infections / Q000175:diagnosis / Q000382:microbiology; D013211:Staphylococcus aureus / Q000235:genetics*; D013290:Streptococcal Infections / Q000175:diagnosis / Q000382:microbiology; D013291:Streptococcus / Q000145:classification / Q000235:genetics*