Use of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry To Identify Vancomycin-Resistant Enterococci and Investigate the Epidemiology of an Outbreak

Abstract

The control of vancomycin-resistant enterococci (VRE) has become an increasing burden on health care resources since their discovery over 20 years ago. Current techniques employed for their detection include time-consuming and laborious phenotypic methods or molecular methods requiring costly equipment and consumables and highly trained staff. An accurate, rapid diagnostic test has the ability to greatly reduce the spread of this organism, which has the ability to colonize patients for long periods, potentially even lifelong. Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) is a technology with the ability to identify organisms in seconds and has shown promise in the identification of other forms of antimicrobial resistance in other organisms. Here we show that MALDI-TOF MS is capable of rapidly and accurately identifying vanB -positive Enterococcus faecium VRE from susceptible isolates. Internal validation of the optimal model generated produced a sensitivity of 92.4% and a specificity of 85.2%. Prospective validation results, following incorporation into the routine laboratory work flow, demonstrated a greater sensitivity and specificity at 96.7% and 98.1%, respectively. In addition, the utilization of MALDI-TOF MS to determine the relatedness of isolates contributing to an outbreak is also demonstrated.

Instant screening and verification of carbapenemase activity in Bacteroides fragilis in positive blood culture, using matrix-assisted laser desorption ionization–time of flight mass spectrometry

“…There are several publications showing this type of reanalysis or subtyping (Griffin et al, 2012;Josten et al, 2013;Nagy et al, 2013). Nagy et al (2011a) showed the possibility to separate Bacteroides fragilis strains that carry the cfiA gene from those that do not.…”

Screening municipal wastewater effluent and surface water used for drinking water production for the presence of ampicillin and vancomycin resistant enterococci

“…The vanA resistance operon is acquired through the Tn1546 transposon, and the vanB resistance operon is acquired through the exchange of transposons Tn1547 and/or Tn5382 (Kak and Chow, 2002). Vancomycin intrinsically resistant species do not cause the same infection control concerns as E. faecium or E. faecalis VRE, as their resistance is chromosomal rather than plasmid mediated (Griffin et al, 2012). The transfer of resistant bacteria from environmental compartments to humans may occur through contaminated food (Perreten et al, 1997), manure (if used as a fertilizer) and contaminated surface water used for irrigation or as recreational water.…”

Identification of Rare Pathogenic Bacteria in a Clinical Microbiology Laboratory: Impact of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry

“…MALDI-TOF MS has been used to identify bacterial species and subspecies (14,15), and in some outbreaks, MALDI-TOF MS has been reported to be able to identify the lineages of strains (16)(17)(18). Recently, MALDI-TOF MS has also been used to detect clinical pathogens previously misidentified or ambiguously identified (19)(20)(21)(22)(23)(24).…”