title: Virulence determinants in clinical Staphylococcus aureus from monomicrobial and polymicrobial infections of diabetic foot ulcers.
abstract: Antibiotic resistance in Staphylococcus aureus is a major public health concern, and methicillin-resistant S. aureus has emerged as an important pathogen. We characterized S. aureus isolates from monomicrobial and polymicrobial wound infections from 200 diabetic individuals with foot ulcers to understand their underlying diversity and pathogenicity. Staphylococcal cassette chromosome mec typing was performed, and genes coding for production of biofilm, Panton-Valentine leukocidin, toxic shock syndrome toxin and leukotoxins DE and M were screened. Biofilm production was also quantified by the tissue culture plate method. Strains were genotyped using multilocus sequence typing, multiple-locus variable number tandem repeat analysis and repetitive sequence PCR methods. Polymicrobial infections were present in 115 samples, 61 samples showed monomicrobial infection and 24 samples were culture negative. Polymicrobial infections were significantly higher in patients with previous amputation history. Of the 86 samples infected with S. aureus, virulence genes were found in 81 isolates, and 41 isolates possessed more than one virulence gene. Strains which contained pvl gene alone or luk-DE alone were significantly higher in polymicrobial wounds. Based on biofilm production, 18.6 % of isolates were classified as high, 24.4 % as moderate and 57 % as low biofilm producers. Genotyping of 30 strains revealed 10 different sequence types with a strong association among sequence types, specific virulence markers and antibiotic resistance profiles. Moreover, isolates from monomicrobial and polymicrobial wounds differed significantly in their virulence potential and the sequence types to which they belonged, and these are helpful in mapping the evolution of the identified strains of S. aureus.
authors.affiliation: Department of Biotechnology, School of Life Sciences, Manipal University, Manipal 576104, India.
authors.forename: Kavitha
authors.initials: K
authors.lastname: Shettigar
authors.affiliation: Department of Biotechnology, School of Life Sciences, Manipal University, Manipal 576104, India.
authors.forename: Spoorthi
authors.initials: S
authors.lastname: Jain
authors.affiliation: Department of Biotechnology, School of Life Sciences, Manipal University, Manipal 576104, India.
authors.forename: Deepika V
authors.initials: DV
authors.lastname: Bhat
authors.affiliation: Department of Medicine, Kasturba Medical College, Manipal University, Manipal 576104, India.
authors.forename: Raviraj
authors.initials: R
authors.lastname: Acharya
authors.affiliation: Department of Surgery, Kasturba Medical College, Manipal University, Manipal 576104, India.
authors.forename: Lingadakai
authors.initials: L
authors.lastname: Ramachandra
authors.affiliation: Department of Cell and Molecular Biology, School of Life Sciences, Manipal University, Manipal 576104, India.
authors.forename: Kapaettu
authors.initials: K
authors.lastname: Satyamoorthy
authors.affiliation: Department of Biotechnology, School of Life Sciences, Manipal University, Manipal 576104, India.
authors.forename: Thokur Sreepathy
authors.initials: TS
authors.lastname: Murali
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001426:Bacterial Proteins / Q000235:genetics; D018441:Biofilms; D060085:Coinfection / Q000382:microbiology*; D017719:Diabetic Foot / Q000382:microbiology*; D024901:Drug Resistance, Multiple, Bacterial; D005838:Genotype; D006801:Humans; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus / Q000302:isolation & purification / Q000472:pathogenicity*; D008875:Middle Aged; D018598:Minisatellite Repeats; D058885:Multilocus Sequence Typing; D016133:Polymerase Chain Reaction; D013203:Staphylococcal Infections / Q000453:epidemiology / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity*; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; D037521:Virulence Factors