Abstract
BackgroundThe production of staphylocoagulase (SC) causing the plasma coagulation is one of the important characteristics of Staphylococcus aureus. Although SCs have been classified into 10 serotypes based on the differences in the antigenicity, genetic bases for their diversities and relatedness to chromosome types are poorly understood.Methodology/Principal FindingsWe compared the nucleotide sequences of 105 SC genes (coa), 59 of which were determined in this study. D1 regions, which contain prothrombin-activating and -binding domains and are presumed to be the binding site of each type-specific antiserum, were classified into twelve clusters having more than 90% nucleotide identities, resulting to create two novel SC types, XI and XII, in addition to extant 10 types. Nine of the twelve SC types were further subdivided into subtypes based on the differences of the D2 or the central regions. The phylogenetical relations of the D1 regions did not correlate exactly with either one of agr types and multilocus sequence types (STs). In addition, genetic analysis showed that recombination events have occurred in and around coa. So far tested, STs of 126 S. aureus strains correspond to the combination of SC type and agr type except for the cases of CC1 and CC8, which contained two and three different SC types, respectively.ConclusionThe data suggested that the evolution of coa was not monophyletic in the species. Chromosomal recombination had occurred at coa and agr loci, resulting in the carriage of the combinations of allotypically different important virulence determinants in staphylococcal chromosome.
Highlights
Staphylococcus aureus is a persistent resident of the nasal membrane and skin of warm-blooded animals, and a major causative agent of hospital and community-associated infections
Chromosomal recombination had occurred at coa and agr loci, resulting in the carriage of the combinations of allotypically different important virulence determinants in staphylococcal chromosome
We studied correlation of the two typing methods with the SC typing by using 105 S. aureus strains with their coa sequenced and 21 strains whose SC types were determined by the multiplex PCRs (M-PCRs) and serotyping
Summary
Staphylococcus aureus is a persistent resident of the nasal membrane and skin of warm-blooded animals, and a major causative agent of hospital and community-associated infections. Staphylocoagulase (SC) that causes coagulation of plasma is one of the extracellular virulence factors produced by S. aureus strains, and is regarded as a marker for discriminating S. aureus from other less pathogenetic staphylococci called as coagulase-negative staphylococci. Variations in SCs have been noticed as the differences in the antigenicity, and SCs have been classified into 10 serotypes by inhibition test of their clotting activity using type-specific antibodies against each serotype [3,4]. Comparisons of nucleotide sequences as well as their deduced amino acid sequences of coa of 10 serotypes showed the D1 and the D2. The production of staphylocoagulase (SC) causing the plasma coagulation is one of the important characteristics of Staphylococcus aureus. SCs have been classified into 10 serotypes based on the differences in the antigenicity, genetic bases for their diversities and relatedness to chromosome types are poorly understood
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