Comparative Genomics of Staphylococcus aureus Musculoskeletal Isolates

Abstract

Much of the research aimed at defining the pathogenesis of Staphylococcus aureus has been done with a limited number of strains, most notably the 8325-4 derivative RN6390. Several lines of evidence indicate that this strain is unique by comparison to clinical isolates of S. aureus. Based on this, we have focused our efforts on two clinical isolates (UAMS-1 and UAMS-601), both of which are hypervirulent in our animal models of musculoskeletal infection. In this study, we used comparative genomic hybridization to assess the genome content of these two isolates relative to RN6390 and each of seven sequenced S. aureus isolates. Our comparisons were done by using an amplicon-based microarray from the Pathogen Functional Genomics Resource Center and an Affymetrix GeneChip that collectively represent the genomes of all seven sequenced strains. Our results confirmed that UAMS-1 and UAMS-601 share specific attributes that distinguish them from RN6390. Potentially important differences included the presence of cna and the absence of isaB, sarT, sarU, and sasG in the UAMS isolates. Among the sequenced strains, the UAMS isolates were most closely related to the dominant European clone EMRSA-16. In contrast, RN6390, NCTC 8325, and COL formed a distinct cluster that, by comparison to the other four sequenced strains (Mu50, N315, MW2, and SANGER-476), was the most distantly related to the UAMS isolates and EMRSA-16.Staphylococcus aureus is an opportunistic pathogen capable of causing serious human infections. An increasing number of these infections are recalcitrant to antimicrobial therapy. Indeed, the National Nosocomial Infections Surveillance System has seen a rise in oxacillin-resistant S. aureus (ORSA) among hospital isolates from approximately 4% in the 1980s to Ͼ50% in the late 1990s (47). Of recent concern is the increasing prevalence of ORSA among patients suffering from community-acquired infections (19). Research comparing these community-acquired ORSA isolates with hospital-acquired ORSA isolates found that the increase in community-acquired ORSA infections can be attributed to the acquisition of a novel SCCmec element (19). Furthermore, both vancomycin-intermediate and vancomycin-resistant S. aureus were recently described (66), confirming that S. aureus has the potential to resist even those antimicrobials often reserved as a "last resort." This emphasizes the evolutionary adaptability of S. aureus and highlights the importance of finding novel therapeutic approaches in the face of such a readily adaptable pathogen (50).Much of the research aimed at identifying novel therapeutic targets for the treatment of S. aureus infections has been directed at identification of specific virulence factors and regulatory circuits that are relevant to the disease process. Almost invariably, these studies used the prototypic lab strain NCTC 8325 or its derivatives. The single most widely studied strain is RN6390, which is an 8325-4 strain generated by curing three prophage from NCTC 8325 (1, 12, 45). However, RN6390 has an 11-b...

Characterizing the Effect of theStaphylococcus aureusVirulence Factor Regulator, SarA, on Log-Phase mRNA Half-Lives

“…S. aureus strain UAMS-1 is a well-characterized, highly virulent clinical isolate, and its genetic composition has recently been determined (7,8,10,11,16). The mRNA half-lives of all transcripts produced during log-phase UAMS-1 and isogenic sarA mutant cell growth were measured using S. aureus Affymetrix GeneChips (Saur2a).…”

Reemergence of antibiotic-resistant Staphylococcus aureus in the genomics era

“…There is not enough space here to highlight all the comparative genomics analyses of S. aureus performed to date (22,(73)(74)(75). However, the study by Fitzgerald et al was the first to use a comparative microarray approach to study the evolution of MRSA (76).…”

Staphylococcus Infection Associated with Arthroplasty

“…However, these studies did not use a collection of isolates from specific invasive diseases and therefore do not rule out the possibility that specific lineages or genes are associated with specific types of infection, such as osteomyelitis or septic arthritis. To date, the only genome comparison study relevant to S. aureus bone infections has been done using comparative genome microarray hybridisations of the S. aureus UAMS-1 strain, isolated from an osteomyelitis patient, with a range of genome sequenced strains [41]. These authors found variations in the complement of adhesin, toxin, exoenzyme and regulatory genes.…”