Vancomycin minimum inhibitory concentrations using different susceptibility methods in Staphylococcus aureus isolates

Sousa, Aline Gil Pestana; Costa, Thaina Miranda da; Cavalcante, Fátima Gonçalves; Chamon, Raiane Cardoso; Ferreira, Dennis Carvalho; Nouér, Simone Aranha; Santos, Kátia Regina Netto dos

doi:10.3855/jidc.4395

Cited by 2 publications

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“…31 Vancomycin MICs generated by Etest® were consistently higher in the current study, according to other studies showing that Etest® MICs tend to be higher than BMD MICs. 16,32,33 The falsely elevated MIC of vancomycin may influence the clinicians to use another antimicrobial to replace vancomycin, and in another scenario, with the precise MIC value, vancomycin would be the first treatment choice. 34 Although new anti-staphylococcal antimicrobials have recently been developed, such as linezolid, vancomycin still remains the main therapeutic choice, mainly due to the low cost and the large number of clinical trials when compared to the new drugs.…”

Section: Discussionmentioning

confidence: 99%

Comparative evaluation of the Phoenix®, VITEK® 2, E-test® and microdilution test for vancomycin susceptibility testing in Staphylococcus aureus isolated from bloodstream infection

Rodrigues

Costa

Santos

et al. 2021

BJHBS

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Introduction: Staphylococcus aureus bacteremia causes significant morbidity and mortality, mainly by methicillin-resistant S. aureus (MRSA). Currently, vancomycin is the main choice for the treatment of infections by MRSA. Broth microdilution (BMD) remains the gold standard for measuring vancomycin MIC. However, most clinical laboratories employ practical methods in the routines, but these methods may not determine accurate vancomycin MIC values. Objectives: This study aimed to evaluate the accuracy of VITEK®2, Phoenix® and Etest® methods against BMD. Materials and Methods: A total of 78 strains (27 methicillin-sensitive S. aureus and 51 MRSA) were isolated from bloodstream infections. The vancomycin MIC was determined following CLSI and the manufacturers' recommendations. We also performed SCCmec typing, in order to identify their vancomycin MIC ratio values. Results: Most of all isolates showed values of MIC = 1 μg/mL by BMD and Phoenix®, while Etest® and VITEK® 2 determined the majority with MIC = 1.5 and 0.5 μg/mL, respectively. Thus, Etest® and VITEK® 2 tended to overestimate and underestimate, respectively, the MIC values. Three MRSA isolates that were vancomycin susceptible by the BMD were vancomycin-intermediate by Etest®. The SCCmec II (39%) and IV (51%) were the most frequent, and there was no relationship between the type of SCCmec and the MIC values. Conclusions: The results showed that vancomycin MICs vary according to the test method. It is essential that clinicians consider the differences in MIC results determined by different methods, since the MIC value is generally the parameter used by clinicians to select the appropriate therapy.

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Section: Discussionmentioning

confidence: 99%

Comparative evaluation of the Phoenix®, VITEK® 2, E-test® and microdilution test for vancomycin susceptibility testing in Staphylococcus aureus isolated from bloodstream infection

Rodrigues

Costa

Santos

et al. 2021

BJHBS

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“…We previously reported that 124 S . aureus isolates from patient with bloodstream infection (BSI) from two tertiary hospitals in Rio de Janeiro, between 2008 and 2009, were susceptible to vancomycin [14]. However, VISA and hVISA infections are reported worldwide and have been associated with poor patient outcomes [7], [8], [15].…”

Section: Introductionmentioning

confidence: 99%

Clinical and Microbiological Characteristics of Heteroresistant and Vancomycin-Intermediate Staphylococcus aureus from Bloodstream Infections in a Brazilian Teaching Hospital

et al. 2016

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This study analyzed clinical and microbiological characteristics of heteroresistant (hVISA) and vancomycin-intermediate Staphylococcus aureus (VISA) from bloodstream infections (BSI) in a Brazilian teaching hospital, between 2011 and 2013. Minimum inhibitory concentrations (MIC) of antimicrobials were determined by broth microdilution method and SCCmec was detected by PCR. Isolates with a vancomycin MIC ≥ 2mg/L were cultured on BHI agar with 3, 4 or 6 mg/L (BHIa3, BHIa4 or BHIa6) of vancomycin and BHIa4 with casein (BHIa4ca). Macromethod Etest® and Etest® Glicopeptides Resistance Detection were also used. VISA and hVISA isolates were confirmed by the population analysis profile then typed by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing. Medical data from the patients were obtained from their medical records. Among 110 consecutive isolates, 31 (28%) were MRSA and carried the SCCmec type II (15 isolates) or IV (16 isolates). Vancomycin MIC50 and MIC90 were 1 and 2 mg/L, respectively. MRSA isolates had increased non-susceptibility to daptomycin (p = 0.0003). Six (5%) isolates were VISA, four of which were MRSA, three SCCmec type II/USA100/ST5 and one type IV/USA800/ST3192. One MRSA SCCmec II isolate grew on agar BHIa3, BHIa4 and BHIa4ca, and it was confirmed as hVISA. Among the six VISA isolates, five (83%) grew on BHIa3 and three (50%) on BHI4ca. Four of the six VISA isolates and the one hVISA isolate were from patients who had undergone dialysis. Thus, a possible dissemination of the SCCmec II/USA100/ST5 lineage may have occurred in the hospital comprising the VISA, hVISA and daptomycin non-susceptible S. aureus Brazilian isolates from health care associated bloodstream infections.

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Vancomycin minimum inhibitory concentrations using different susceptibility methods in Staphylococcus aureus isolates

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Cited by 2 publications

References 18 publications

Comparative evaluation of the Phoenix®, VITEK® 2, E-test® and microdilution test for vancomycin susceptibility testing in Staphylococcus aureus isolated from bloodstream infection

Comparative evaluation of the Phoenix®, VITEK® 2, E-test® and microdilution test for vancomycin susceptibility testing in Staphylococcus aureus isolated from bloodstream infection

Clinical and Microbiological Characteristics of Heteroresistant and Vancomycin-Intermediate Staphylococcus aureus from Bloodstream Infections in a Brazilian Teaching Hospital

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