Clinical Features of Heteroresistant Vancomycin-Intermediate<i>Staphylococcus aureus</i>Bacteremia versus Those of Methicillin-Resistant<i>S. aureus</i>Bacteremia

Maor, Yasmin; Hagin, Michal; Belausov, Natasha; Keller, Nathan; Ben-David, Debbi; Rahav, Galia

doi:10.1086/596629

Cited by 148 publications

(112 citation statements)

References 21 publications

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“…Those authors were not able to relate these complications to low serum vancomycin levels. The infection-attributable mortality for hVISA was similar to that for MRSA bacteremia (193).…”

Section: Clinical Studiesmentioning

confidence: 62%

“…Essentially, an hVISA isolate is an S. d S. aureus with reduced susceptibility (SA-RVS) is defined as follows: (i) MIC of Ն4 g per ml (91,306) or (ii) area under vancomycin concentrationkill curve of Ն0.9 of the AUC of type strain Mu3 (124). hVISA is defined as follows: (i) VSSA strain that upon subculture stably produces subcolonies with MICs in the VISA/VRSA range at a frequency of Ն1 ϫ 10 6 according to the population analysis profile (PAP) (114); (ii) AUC ratio of Ն0.9 of the AUC of type strain Mu3, referred to as PAP/AUC (48,118,155); or (iii) modified high-inoculum Etest read at 48 h (193,194).…”

Section: Heterogeneous Vancomycin-intermediate Staphylococcus Aureus mentioning

confidence: 99%

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Reduced Vancomycin Susceptibility inStaphylococcus aureus, Including Vancomycin-Intermediate and Heterogeneous Vancomycin-Intermediate Strains: Resistance Mechanisms, Laboratory Detection, and Clinical Implications

et al. 2010

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SUMMARY The emergence of vancomycin-intermediate Staphylococcus aureus (VISA) and heterogeneous vancomycin-intermediate Staphylococcus aureus (hVISA) over the past decade has provided a challenge to diagnostic microbiologists to detect these strains, clinicians treating patients with infections due to these strains, and researchers attempting to understand the resistance mechanisms. Recent data show that these strains have been detected globally and in many cases are associated with glycopeptide treatment failure; however, more rigorous clinical studies are required to clearly define the contribution of hVISA to glycopeptide treatment outcomes. It is now becoming clear that sequential point mutations in key global regulatory genes contribute to the hVISA and VISA phenotypes, which are associated predominately with cell wall thickening and restricted vancomycin access to its site of activity in the division septum; however, the phenotypic features of these strains can vary because the mutations leading to resistance can vary. Interestingly, changes in the staphylococcal surface and expression of agr are likely to impact host-pathogen interactions in hVISA and VISA infections. Given the subtleties of vancomycin susceptibility testing against S. aureus, it is imperative that diagnostic laboratories use well-standardized methods and have a framework for detecting reduced vancomycin susceptibility in S. aureus.

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“…Those authors were not able to relate these complications to low serum vancomycin levels. The infection-attributable mortality for hVISA was similar to that for MRSA bacteremia (193).…”

Section: Clinical Studiesmentioning

confidence: 62%

Section: Heterogeneous Vancomycin-intermediate Staphylococcus Aureus mentioning

confidence: 99%

Reduced Vancomycin Susceptibility inStaphylococcus aureus, Including Vancomycin-Intermediate and Heterogeneous Vancomycin-Intermediate Strains: Resistance Mechanisms, Laboratory Detection, and Clinical Implications

et al. 2010

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“…Vancomycin MICs of Ͼ1 g/ml have been associated with hVISA (2,12,33), but this is not a strong indicator for hVISA because Etest and Sensititre reported equally high MICs in the vancomycin-susceptible isolates. The incidence of hVISA in other hospitals has varied, ranging from 0 to 50% (3,4,7,13,21,22,23,25,28,29,34,35,50,52,54). The type of screening test used to detect hVISA and the number of isolates screened are responsible for this wide range.…”

Section: Figmentioning

confidence: 99%

Vancomycin Susceptibility Trends and Prevalence of Heterogeneous Vancomycin-Intermediate Staphylococcus aureus in Clinical Methicillin-Resistant S. aureus Isolates

Pitz

Hermsen

et al. 2011

J Clin Microbiol

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“…Patients who have serious high-inoculum infections (i.e., infective endocarditis, medical device infections, etc.) with MRSA and for which the strain has been identified as heteroresistant vancomycin-intermediate S. aureus (hVISA) are also more likely to experience prolonged days of bacteremia, increased complications, multiple drug resistance, and relapse or recurrence of infection than those patients with susceptible strains (12)(13)(14)(15)(16)(17)(18). It has been demonstrated that some percentage of hVISA infections exist within the vancomycin susceptibility range and that the prevalence of these strains increases as the MIC reaches up to the breakpoint of 2 mg/liter (19)(20)(21).…”

mentioning

confidence: 99%

Evaluation of Vancomycin Susceptibility Testing for Methicillin-Resistant Staphylococcus aureus: Comparison of Etest and Three Automated Testing Methods

et al. 2013

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We evaluated the ability of four commercial MIC testing systems (MicroScan, Vitek 2, Phoenix, and Etest) to detect vancomycin MIC values of <1 to >2 in 200 methicillin-resistant Staphylococcus aureus (MRSA) strains compared to the Clinical and Laboratory Standards Institute broth microdilution (BMD) reference methods. Compared to the BMD method, absolute agreement (0 ؎ dilution) was highest for the Phoenix system (66.2%) and the MicroScan turbidity method (61.8%), followed by the Vitek 2 system (54.3%). The Etest produced MIC values 1 to 2 dilutions higher than those produced by the BMD method (36.7% agreement). Of interest, the MicroScan system (prompt method) was more likely to overcall an MIC value of 1 mg/liter (74.1%), whereas the Phoenix (76%) and Vitek 2 (20%) systems had a tendency to undercall an MIC of 2 mg/liter. The ability to correctly identify vancomycin MIC values of 1 and 2 has clinical implications and requires further evaluation.T he overall prevalence of methicillin-resistant Staphylococcus aureus (MRSA) continues to increase, with vancomycin (VAN) remaining the mainstay of therapy for serious infections (1-3). Over the last several years, there have been a number of studies that have demonstrated an association between vancomycin MICs of 1.5 or 2 mg/liter and failure of vancomycin therapy, even though these values lie within the Clinical and Laboratory Standards Institute's (CLSI's) and the FDA's acceptable vancomycin susceptibility range (Յ2 mg/liter). The majority of these reports were derived from patients with MRSA-complicated bacteremia in whom a vancomycin MIC of 1.5 or 2 mg/liter was associated with persistent signs and symptoms of infection, including prolonged days of bacteremia, increased complications, increased lengths of hospital stay, and mortality (4-9). A recent observational study of 532 patients with MRSA and methicillinsusceptible Staphylococcus aureus (MSSA) bacteremia noted a significantly higher 30-day mortality rate associated with patients who had an isolate for which the MIC exceeded 1.5 mg/liter (by Etest methods). Of interest, this association did not seem to be related to vancomycin treatment, since patients who had MSSA bacteremia with an elevated vancomycin MIC and were treated with flucloxacillin had worse clinical outcomes than flucloxacillin-treated patients with MSSA bacteremia that had a lower vancomycin MIC value (P ϭ 0.012) (10). In addition, a recent systematic review and meta-analysis of the literature regarding the relationship of vancomycin susceptibility and patient outcome concluded that vancomycin MIC values of 1.5 or 2 mg/liter were associated with greater treatment failure and mortality rates in patients with MRSA infections (11). Patients who have serious high-inoculum infections (i.e., infective endocarditis, medical device infections, etc.) with MRSA and for which the strain has been identified as heteroresistant vancomycin-intermediate S. aureus (hVISA) are also more likely to experience prolonged days of bacteremia, increased complications, m...

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Clinical Features of Heteroresistant Vancomycin-IntermediateStaphylococcus aureusBacteremia versus Those of Methicillin-ResistantS. aureusBacteremia

Cited by 148 publications

References 21 publications

Reduced Vancomycin Susceptibility inStaphylococcus aureus, Including Vancomycin-Intermediate and Heterogeneous Vancomycin-Intermediate Strains: Resistance Mechanisms, Laboratory Detection, and Clinical Implications

Reduced Vancomycin Susceptibility inStaphylococcus aureus, Including Vancomycin-Intermediate and Heterogeneous Vancomycin-Intermediate Strains: Resistance Mechanisms, Laboratory Detection, and Clinical Implications

Vancomycin Susceptibility Trends and Prevalence of Heterogeneous Vancomycin-Intermediate Staphylococcus aureus in Clinical Methicillin-Resistant S. aureus Isolates

Evaluation of Vancomycin Susceptibility Testing for Methicillin-Resistant Staphylococcus aureus: Comparison of Etest and Three Automated Testing Methods

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