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Virulence Determinants in Staphylococcus aureus Clones Causing Osteomyelitis in Italy.

ABSTRACT: Staphylococcus aureus is the most common pathogen causing osteomyelitis (OM). The aim of this study was to explore the clonal complex (CC) distribution and the pattern of virulence determinants of S. aureus isolates from OM in Italy. Whole-genome sequencing was performed on 83 S. aureus isolates from OM cases in six hospitals. Antibiotic susceptibility tests showed that 30.1% of the isolates were methicillin-resistant S. aureus (MRSA). The most frequent CCs detected were CC22, CC5, CC8, CC30, and CC15, which represent the most common lineages circulating in Italian hospitals. MRSA were limited in the number of lineages (CC22, CC5, CC8, and CC1). Phylogenetic analysis followed the sequence type-CC groupings and revealed a non-uniform distribution of the isolates from the different hospitals. No significant difference in the mean number of virulence genes carried by MRSA or MSSA isolates was observed. Some virulence genes, namely cna, fib, fnbA, coa, lukD, lukE, sak, and tst, were correlated with the CC. However, different categories of virulence factors, such as adhesins, exoenzymes, and toxins, were frequently detected and unevenly distributed among all lineages. Indeed, each lineage carried a variable combination of virulence genes, likely reflecting functional redundancy, and arguing for the importance of those traits for the pathogenicity in OM. In conclusion, no specific genetic trait in the most frequent lineages could explain their high prevalence among OM isolates. Our findings highlight that CCs detected in OM isolates follow the epidemiology of S. aureus infections in the country. It is conceivable that any of the most common S. aureus CC can cause a variety of infections, including OM.

SUBMITTER: Pimentel de Araujo F

PROVIDER: S-EPMC8927738 | biostudies-literature | 2022

REPOSITORIES: biostudies-literature

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Virulence Determinants in Staphylococcus aureus Clones Causing Osteomyelitis in Italy.

Pimentel de Araujo Fernanda F Pirolo Mattia M Monaco Monica M Del Grosso Maria M Ambretti Simone S Lombardo Donatella D Cassetti Tiziana T Gargiulo Raffaele R Riccobono Eleonora E Visca Paolo P Pantosti Annalisa A

Frontiers in microbiology 20220303

Staphylococcus aureus is the most common pathogen causing osteomyelitis (OM). The aim of this study was to explore the clonal complex (CC) distribution and the pattern of virulence determinants of S. aureus isolates from OM in Italy. Whole-genome sequencing was performed on 83 S. aureus isolates from OM cases in six hospitals. Antibiotic susceptibility tests showed that 30.1% of the isolates were methicillin-resistant S. aureus (MRSA). The most frequent CCs detected w ...[more]

PMID: 35308345

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Project description:UNLABELLED:Staphylococcus aureus is a Gram-positive, commensal bacterium known to asymptomatically colonize the human skin, nares, and gastrointestinal tract. Colonized individuals are at increased risk for developing S. aureus infections, which range from mild skin and soft tissue infections to more severe diseases, such as endocarditis, bacteremia, sepsis, and osteomyelitis. Different virulence factors are required for S. aureus to infect different body sites. In this study, virulence gene expression was analyzed in two S. aureus isolates during nasal colonization, bacteremia and in the heart during sepsis. These models were chosen to represent the stepwise progression of S. aureus from an asymptomatic colonizer to an invasive pathogen. Expression of 23 putative S. aureus virulence determinants, representing protein and carbohydrate adhesins, secreted toxins, and proteins involved in metal cation acquisition and immune evasion were analyzed. Consistent upregulation of sdrC, fnbA, fhuD, sstD, and hla was observed in the shift between colonization and invasive pathogen, suggesting a prominent role for these genes in staphylococcal pathogenesis. Finally, gene expression data were correlated to the roles of the genes in pathogenesis by using knockout mutants in the animal models. These results provide insights into how S. aureus modifies virulence gene expression between commensal and invasive pathogens. IMPORTANCE:Many bacteria, such as Staphylococcus aureus, asymptomatically colonize human skin and nasal passages but can also cause invasive diseases, such as bacteremia, pneumonia, sepsis, and osteomyelitis. The goal of this study was to analyze differences in the expression of selected S. aureus genes during a commensal lifestyle and as an invasive pathogen to gain insight into the commensal-to-pathogen transition and how a bacterial pathogen adapts to different environments within a host (e.g., from nasal colonization to invasive pathogen). The gene expression data were also used to select genes for which to construct knockout mutants to assess the role of several proteins in nasal colonization and lethal bacteremia. These results not only provide insight into the factors involved in S. aureus disease pathogenesis but also provide potential therapeutic targets.

Project description:BackgroundStaphylococcus aureus causes many human infections, including wound infections, and its pathogenicity is mainly influenced by several virulence factors.AimThis study aimed to detect virulence genes (hla, sea, icaA, and fnbA) in S. aureus isolated from different wound infections among Egyptian patients admitted to Minia University Hospital. This study also aimed to investigate the prevalence of these genes in methicillin-resistant S. aureus (MRSA), methicillin-susceptible S. aureus (MSSA), and vancomycin-resistant S. aureus isolates and the resistance and sensitivity to different antibiotic classes.MethodsA cross-sectional study was carried out from November 2019 to September 2021. Standard biochemical and microbiological tests revealed 59 S. aureus isolates. The Kirby-Bauer disc diffusion method was used to determine antibiotic susceptibility. DNA was extracted using a DNA extraction kit, and polymerase chain reaction was used to amplify all genes.ResultsA total of 59 S. aureus isolates were detected from 51 wound samples. MRSA isolates accounted for 91.5%, whereas MSSA isolates accounted for 8.5%. The multidrug resistance (MDR) percentage in S. aureus isolates was 54.2%. S. aureus showed high sensitivity pattern against vancomycin, linezolid, and chloramphenicol. However, a high resistance pattern was observed against oxacillin and piperacillin. sea was the most predominant gene (72.9%), followed by icaA (49.2%), hla (37.3%), and fnbA (13.6%). sea was the commonest virulence gene among MRSA isolates (72.2%), and a significant difference in the distribution of icaA was found. However, sea and icaA were the commonest genes among MSSA isolates (79.9%). The highest distribution of sea was found among ciprofloxacin-resistant isolates (95.2%).ConclusionThe incidence of infections caused by MDR S. aureus significantly increased with MRSA prevalence. sea is the most predominant virulence factor among antibiotic-resistant strains with a significant correlation to piperacillin, gentamicin, and levofloxacin.

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Virulence Determinants in Staphylococcus aureus Clones Causing Osteomyelitis in Italy.

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Virulence Determinants in <i>Staphylococcus aureus</i> Clones Causing Osteomyelitis in Italy.

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