Use of MALDI-TOF MS to Discriminate between Biofilm-Producer and Non-Producer Strains of Staphylococcus epidermidis.

Pina Caputo,Brunella Perfetto,Giovanna Donnarumma,Maria Di Martino,Francesco Iovino

doi:10.3390/ijerph15081695

Abstract

For the management of Staphylococci coagulase-negative infection, often related to biofilm formation, rapid and accurate identification is necessary in choosing a correct antibiotic therapy. Matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) is becoming increasingly important for bacterial identification over traditional methods. Our aim was to validate the use of MALDI to discriminate Staphylococcus epidermidis biofilm-producing strains. Clinical strains coming from suture wires were identified and their protein profiles were compared to that obtained from two ATCC reference strains (biofilm producer and non-producer). MALDI identified the eighteen isolates as S. epidermidis, combining sixteen profiles with the biofilm producer and two with the non-producer, confirming the results of crystal violet assay. Our data highlight that MALDI can be considered a good tool to discriminate between biofilm-producer and non-producer strains of S. epidermidis, thus helping to establish an effective antibiotic therapy.

Highlights

Clinical microbiology laboratories often use conventional methods, based on culture with selective media, analysis of microbial phenotypic characteristics, and biochemical tests for microbial identification
MALDI can be considered a good tool to discriminate between biofilm-producer and non-producer strains of S. epidermidis, helping to establish an effective antibiotic therapy
We established an arbitrary index to indicate the rate of biofilm production, in relation to the optical density obtained in crystal violet assay

Summary

Introduction

Clinical microbiology laboratories often use conventional methods, based on culture with selective media, analysis of microbial phenotypic characteristics, and biochemical tests for microbial identification. A rapid and accurate identification of microorganisms is necessary for the management of infectious diseases, to choose an effective therapy For this reason, the routine identification of bacteria and fungi by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) has become a true revolution in clinical microbiology laboratories [1]. The routine identification of bacteria and fungi by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) has become a true revolution in clinical microbiology laboratories [1] This approach generates a mass spectrum with a number of defined protein peaks in the range of 70–200, for about 105 –106 fresh cell biomass. Biofilm is a key virulence factor for a wide range of microorganisms responsible for chronic infections. In addition the resident microorganisms become resistant to drugs and to host immune responses [2]

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