Prevalence of vancomycin-intermediate Staphylococcus aureus (VISA) and heterogeneous VISA among methicillin-resistant S. aureus with high vancomycin minimal inhibitory concentrations in Taiwan: A multicenter surveillance study, 2012–2013

Abstract

Growing hVISA prevalence was highly suspected. Longitudinal surveillance of this phenomenon and monitoring of its clinical impact are necessary.

Características moleculares de Staphylococcus aureus suscetível à vancomicina poderia ajudar a prever falhas no tratamento devido à reduzida suscetibilidade à vancomicina

“…PAP/AUC was performed as previously described by Huang et al 11 Briefly, a 0.5 McFarland standard suspension from an overnight culture in trypticase soy agar (TSA; Oxoid, Basingstoke, England) was prepared. Serial dilutions (10 -1 a 10 -5 ) were prepared in sterile saline, 10 µL from each dilution was spread onto BHI agar plates containing increasing concentrations of vancomycin (0 µg/mL, 1 µg/mL, 2 µg/mL, 3 µg/mL, 4 µg/mL, 5 µg/mL, 6 µg/mL and 8 µg/mL).…”

“…In previous reports, the frequency of the hVISA has ranged from 0 to 22.1% of MRSA. 11,20,21 Their prevalence among MRSA varies significantly with the geographic area, the source of clinical isolates, and detection methods. 11,21 SCCmec III was the most prevalent type among the MRSA strains, as observed in other studies, and types III and II were more prevalent among isolates with reduced susceptibility to vancomycin (hVISA and VT-MRSA), as also observed in previous studies.…”

“…Although the relevance of hVISA persists unclear, studies speculate that these isolates could be a precursor of VISA phenotype. [9][10][11] MRSA strains also develop vancomycin tolerance, whose infections are even more difficult to treat, especially when they are invasive and present in immunocompromised patients. 7 Additionally, this reduced vancomycin suscepti-bility is associated with dysfunction in the accessory gene regulator (agr) locus, a quorum sensing system that controls the expression of genes encoding virulence factors.…”

Combination Antibiotic Exposure Selectively Alters the Development of Vancomycin Intermediate Resistance in Staphylococcus aureus

“…expansion of this small subpopulation, resulting in VAN treatment failure and a transition to a homogeneous VISA population. These isolates have been associated with poor response to VAN therapy in patients and are frequently more resistant to secondary treatment options (2)(3)(4)(5)(6). VAN treatment failure is a significant clinical concern, and strategies to prevent the emergence and spread of these organisms are needed.…”

Teixobactin: a novel anti-infective agent

“…However, the organism can cause deep-seated, lifethreatening infection, including bacteremia, endocarditis, and end-organ disease [10]. Antibiotic-resistant strains of S. aureus, including vancomyin-intermediate S. aureus and MRSA, were once thought to be limited to specific settings, including healthcare facilities and gymnasiums, we know that this is now longer the case; community-acquired resistant strains appear all over the world [11,12]. These cases present a challenge as there are limited therapeutic options available to treat this potentially-lethal pathogen, and novel treatment options are urgently needed.…”