Pathogenicity and Virulence of the Major Gram-Positive Bacteria—Staphylococci and Enterococci

Dear Colleagues,

The aim of this Special Issue is to elucidate the molecular features of genes, plasmids, and clones of major Gram-positive bacteria, staphylococci, and enterococci.

Among multidrug-resistant (MDR) Gram-positive bacteria, and MRSA (methicillin-resistant Staphylococccus aureus and vancomycin-resistant enterococci (VRE), especially E. faecium) are a most pressing concern.

Staphylococci and enterococci are a significant cause of healthcare-associated infections. Vancomycin, a last-resort glycopeptide, is among the administered antimicrobial agents to fight these bacteria, but the emergence of resistance against such agents leaves some patients with few therapeutic options.

Therefore, surveillance of MDR Gram-positive bacteria and their virulence determinants are important for conducting epidemiological analysis of such factors, designing risk management, and strategically controlling their spread in the community and healthcare facilities because these data are highly relevant to public health. The agr system in S. aureus is a prototype regulator of pathogenesis and controls the expression of virulence factors and antimicrobial resistance genes. However, multiple factors associated with the staphylococci and their environments affect the evolution of antibiotic resistance and virulence.

In recent years, there has been an observed increase in VRE infections in invasive diseases globally and in particular nations. Few analyses suggest that nosocomial VRE infections significantly increase hospital costs compared to infections with vancomycin-susceptible enterococci (VSE). However, comparison of patients with VRE and VSE bacteremias revealed no significant differences in mortality, especially after controlling for factors such as age and APACHE II score. There is no evidence that VRE are more virulent than VSE strains of the same enterococcal spp. Indeed, it is not always easy to assess the clinical significance of VRE in routine cultures or to differentiate colonization from infection. This is especially true for urine or when VRE is part of a polymicrobial infection.

As Guest Editor of this Special Issue, I am delighted to invite colleagues investigating any of the pathogenic staphylococci and enterococci within the areas of their ecology, genetics, genomics, immunology, diagnostic detection, public health, and antimicrobial development to submit their manuscripts to this Special Issue in the form of original research, short communication, and reviews. This includes original clinical and laboratory-based research, together with reports of clinical trials and reviews dealing with the epidemiology, clinical diagnosis, treatment, and control of MDR—Gram-positive bacteria, including MRSA and VRE.

Prof. Dr. Parviz Ahmad-Nejad
Dr. Malik Aydin
Guest Editors

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