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Biosensor for Detection of Antibiotic Resistant Staphylococcus Bacteria

Biosensor for Detection of Antibiotic Resistant Staphylococcus Bacteria

Published on: May 8, 2013

Molecular epidemiology and phenotypes of invasive methicillin-resistant vancomycin-intermediate Staphylococcus aureus

Wei-Yao Wang¹, Chen-Feng Chiu², Yuan-Ti Lee³

¹School of Medicine, Chung Shan Medical University, Taichung, Taiwan; Department of Internal Medicine, Chung Shan Medical University Hospital, Taichung, Taiwan; Department of Medical Laboratory Science and Biotechnology, Central Taiwan University of Science and Technology, Taichung, Taiwan.

Journal of Microbiology, Immunology, and Infection = Wei Mian Yu Gan Ran Za Zhi

|October 12, 2021

Abstract

Background:

Patients with invasive infections caused by methicillin-resistant Staphylococcus aureus (MRSA), especially those with an elevated minimal inhibitory concentration (MIC) of vancomycin (VA), are likely to have treatment failure and poor outcomes. The aim of this study was to delineate and correlate the genotypes and phenotypes of clinical VA-intermediate S. aureus (VISA) from invasive infections in Taiwan.

Methods:

Between 2006 and 2010, a total of 670 non-duplicate MRSA isolates were collected from patients with invasive infections, mostly from blood, as part of a nationwide antimicrobial surveillance program named Tigecycline in vitro Surveillance in Taiwan. Among them, 10 (1.5%) VISA (VA MIC = 4 mg/L) isolates were identified. Molecular typing with staphylococcal cassette chromosome mec (SCCmec), multilocus sequence typing, staphylococcal protein A (spa), mec-associated hypervariable region (dru), accessory gene regulator (agr), and pulse-field gel electrophoresis, and phenotypic analysis including antibiotic susceptibility testing, gene encoding Panton-Valentine leukocidin (pvl), and superantigenic toxin profiles, were analyzed.

Results:

All but one isolate was defined as molecular health-care-associated MRSA: 6 as SCCmecIII-ST239-spa t037-agrI-dru7 (1 isolate) and dru14 (5 isolates), 2 as SCCmecII-ST5-spa t586-agrII-dru4, and one as SCCmecII-ST89-spa t3520-agrIII-dru7. One isolate was defined as SCCmecIV-ST59-spa t437-agrI-dru8, which was categorized as molecular community-associated MRSA. Five pulsotypes were identified; only one had a positive D-test and 3 were insusceptible to daptomycin (MIC ≧1 mg/L). Five isolates possessed sea-selk-selq, among them 4 belonged to SCCmecIII-ST239-spa t037-agrI.

Conclusion:

In this study, VISA was rarely isolated from invasive MRSA infections, and most cases harbored limited genotypes and corresponding phenotypes.

Insights

Vancomycin-intermediate Staphylococcus aureus (VISA) is rare in invasive infections, with most cases showing limited genetic diversity and specific phenotypes. This study characterized these rare VISA isolates from Taiwan.

Area of Science:

Microbiology
Infectious Diseases
Genetics

Background:

Invasive infections caused by methicillin-resistant Staphylococcus aureus (MRSA) with high vancomycin minimum inhibitory concentration (MIC) are linked to treatment failure.
Vancomycin-intermediate S. aureus (VISA) poses a significant clinical challenge, necessitating detailed genotypic and phenotypic characterization.

Purpose of the Study:

To delineate and correlate the genotypes and phenotypes of clinical VISA isolates from invasive infections in Taiwan.
To understand the genetic makeup and characteristics of rare VISA strains.

Main Methods:

Analysis of 670 MRSA isolates collected nationwide between 2006-2010.
Identification of 10 VISA isolates (1.5%) with vancomycin MIC = 4 mg/L.
Comprehensive molecular typing (SCCmec, MLST, spa, dru, agr, PFGE) and phenotypic analysis (antibiotic susceptibility, toxin profiles).

Main Results:

Most VISA isolates were classified as healthcare-associated MRSA (SCCmec types II and III).
One community-associated MRSA isolate (SCCmecIV-ST59) was identified.
Limited pulsotypes were observed; some isolates showed reduced susceptibility to daptomycin and carried specific toxin genes (sea, selk, selq).

Conclusions:

VISA is infrequently isolated from invasive MRSA infections in Taiwan.
The identified VISA isolates exhibited limited genotypic and phenotypic diversity.

Read full analysis

Keywords:

Invasive infection MLST Minimum inhibitory concentration SCCmec Vancomycin

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