title: Comparative evaluation of aggressiveness traits in staphylococcal strains from severe infections versus nasopharyngeal carriage.
abstract: Despite their commensal status, staphylococci can become problematic pathogens expressing multiple and redundant virulence factors. This study aimed to evaluate aggressiveness markers comparatively in staphylococcal strains isolated from severe infections versus asymptomatic carriage in order to identify clinically relevant bacterial traits that could easily be detected in clinical practice and could be suggestive for particular host-pathogen interactions such as cyto-adhesion or biofilm formation, ultimately orienting the clinical decision-making process. We have used in vitro phenotypic methods to assess adhesion to and invasion of eukaryotic cells, biofilm development, and expression of soluble virulence factors in 92 Staphylococcus spp. strains. The adhesion index, invasion capacity, biofilm formation and expression of soluble factors did not differ significantly between clinical and commensal strains. The major bacterial traits we found to be significantly more prevalent in clinical staphylococci were the aggregative adhesion pattern (P = 0.012), cluster adhesion (P = 0.001) and tetrad morphology (P = 0.018). The aggregative adhesion pattern was correlated with higher cyto-adhesion (P < 0.001), higher invasion capacity (P = 0.003) and lower Carmeli scores (P = 0.002). Three major bacterial traits, namely tetrad morphology, aggregative adhesion pattern, and resistance to methicillin (acronym: TAM), can be used to compute an aggressiveness score (SAS) predictive of the staphylococcal strain's virulence and capacity to initiate and develop a biofilm-driven chronic infectious process versus a fulminant acute infection, in a susceptible host.
authors.affiliation: Carol Davila University of Medicine and Pharmacy, 8 Eroilor Sanitari, Bucharest, 050474, Romania; National Institute for Infectious Diseases "Prof. Dr. Matei Balş", 1 Dr. Calistrat Grozovici, Bucharest, 021105, Romania.
authors.forename: Oana
authors.initials: O
authors.lastname: Săndulescu
authors.affiliation: Ştefan S. Nicolau Institute of Virology, Romanian Academy, 285 Mihai Bravu, Bucharest, 030304, Romania; Faculty of Biology, University of Bucharest, 1-3 Aleea Portocalelor, Bucharest, 060101, Romania.
authors.forename: Coralia
authors.initials: C
authors.lastname: Bleotu
authors.affiliation: Ştefan S. Nicolau Institute of Virology, Romanian Academy, 285 Mihai Bravu, Bucharest, 030304, Romania.
authors.forename: Lilia
authors.initials: L
authors.lastname: Matei
authors.affiliation: Carol Davila University of Medicine and Pharmacy, 8 Eroilor Sanitari, Bucharest, 050474, Romania; National Institute for Infectious Diseases "Prof. Dr. Matei Balş", 1 Dr. Calistrat Grozovici, Bucharest, 021105, Romania. Electronic address: anca_sc@yahoo.com.
authors.forename: Anca
authors.initials: A
authors.lastname: Streinu-Cercel
authors.affiliation: National Institute of Research "Cantacuzino", 103 Splaiul Independenţei, Bucharest, 050096, Romania.
authors.forename: Mihaela
authors.initials: M
authors.lastname: Oprea
authors.affiliation: National Institute of Research "Cantacuzino", 103 Splaiul Independenţei, Bucharest, 050096, Romania.
authors.forename: Elena Carmina
authors.initials: EC
authors.lastname: Drăgulescu
authors.affiliation: Faculty of Biology, University of Bucharest, 1-3 Aleea Portocalelor, Bucharest, 060101, Romania; Research Institute of the University of Bucharest-ICUB, Life, Environment and Earth Sciences, 91-95 Splaiul Independenţei, Bucharest, 50095, Romania.
authors.forename: Mariana Carmen
authors.initials: MC
authors.lastname: Chifiriuc
authors.affiliation: Carol Davila University of Medicine and Pharmacy, 8 Eroilor Sanitari, Bucharest, 050474, Romania; National Institute for Infectious Diseases "Prof. Dr. Matei Balş", 1 Dr. Calistrat Grozovici, Bucharest, 021105, Romania.
authors.forename: Alexandru
authors.initials: A
authors.lastname: Rafila
authors.affiliation: Department of Research Methodology, University of Medicine and Pharmacy Craiova, 2 Petru Rareş, Craiova, 200349, Romania.
authors.forename: Daniel
authors.initials: D
authors.lastname: Pirici
authors.affiliation: Carol Davila University of Medicine and Pharmacy, 8 Eroilor Sanitari, Bucharest, 050474, Romania; National Institute for Infectious Diseases "Prof. Dr. Matei Balş", 1 Dr. Calistrat Grozovici, Bucharest, 021105, Romania.
authors.forename: Daniela
authors.initials: D
authors.lastname: Tălăpan
authors.affiliation: National Institute for Infectious Diseases "Prof. Dr. Matei Balş", 1 Dr. Calistrat Grozovici, Bucharest, 021105, Romania.
authors.forename: Olga Mihaela
authors.initials: OM
authors.lastname: Dorobăţ
authors.affiliation: Carol Davila University of Medicine and Pharmacy, 8 Eroilor Sanitari, Bucharest, 050474, Romania; National Institute for Infectious Diseases "Prof. Dr. Matei Balş", 1 Dr. Calistrat Grozovici, Bucharest, 021105, Romania.
authors.forename: Alina Cristina
authors.initials: AC
authors.lastname: Neguţ
authors.affiliation: National Institute for Infectious Diseases "Prof. Dr. Matei Balş", 1 Dr. Calistrat Grozovici, Bucharest, 021105, Romania.
authors.forename: Dan
authors.initials: D
authors.lastname: Oţelea
authors.affiliation: Carol Davila University of Medicine and Pharmacy, 8 Eroilor Sanitari, Bucharest, 050474, Romania; National Institute for Infectious Diseases "Prof. Dr. Matei Balş", 1 Dr. Calistrat Grozovici, Bucharest, 021105, Romania.
authors.forename: Ioana
authors.initials: I
authors.lastname: Berciu
authors.affiliation: Carol Davila University of Medicine and Pharmacy, 8 Eroilor Sanitari, Bucharest, 050474, Romania; Experimental Medicine and Fundamental Research Laboratory of Carol Davila University of Medicine and Pharmacy, 1 Dr. Calistrat Grozovici, Bucharest, 021105, Romania.
authors.forename: Daniela Adriana
authors.initials: DA
authors.lastname: Ion
authors.affiliation: National Institute of Research "Cantacuzino", 103 Splaiul Independenţei, Bucharest, 050096, Romania.
authors.forename: Irina
authors.initials: I
authors.lastname: Codiţă
authors.affiliation: Carol Davila University of Medicine and Pharmacy, 8 Eroilor Sanitari, Bucharest, 050474, Romania.
authors.forename: Petre Iacob
authors.initials: PI
authors.lastname: Calistru
authors.affiliation: Carol Davila University of Medicine and Pharmacy, 8 Eroilor Sanitari, Bucharest, 050474, Romania; National Institute for Infectious Diseases "Prof. Dr. Matei Balş", 1 Dr. Calistrat Grozovici, Bucharest, 021105, Romania.
authors.forename: Adrian
authors.initials: A
authors.lastname: Streinu-Cercel
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001422:Bacterial Adhesion; D018441:Biofilms; D002353:Carrier State; D002460:Cell Line; D002648:Child; D002675:Child, Preschool; D015897:Comorbidity; D005260:Female; D014644:Genetic Variation; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D009305:Nasopharynx / Q000382:microbiology*; D019655:Quantitative Trait, Heritable; D012720:Severity of Illness Index; D013203:Staphylococcal Infections / Q000175:diagnosis* / Q000382:microbiology*; D013210:Staphylococcus / Q000145:classification / Q000187:drug effects / Q000472:pathogenicity / Q000502:physiology*; D014774:Virulence; D037521:Virulence Factors; D055815:Young Adult
chemical_list: D000900:Anti-Bacterial Agents; D037521:Virulence Factors
keywords: Adhesion; Biofilm; Invasion; S. aureus; Soluble virulence factors