Rapid Microbial Identification and Antibiotic Resistance Detection by Mass Spectrometric Analysis of Membrane Lipids

Abstract

Infectious diseases have a substantial global health impact. Clinicians need rapid and accurate diagnoses of infections to direct patient treatment and improve antibiotic stewardship. Current technologies employed in routine diagnostics are based on bacterial culture followed by morphological trait differentiation and biochemical testing, which can be time-consuming and labor-intensive. With advances in mass spectrometry (MS) for clinical diagnostics, the U.S. Food and Drug Administration has approved two microbial identification platforms based on matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) MS analysis of microbial proteins. We recently reported a novel and complementary approach by comparing MALDI-TOF mass spectra of microbial membrane lipid fingerprints to identify ESKAPE pathogens. However, this lipid-based approach used a sample preparation method that required more than a working day from sample collection to identification. Here, we report a new method that extracts lipids efficiently and rapidly from microbial membranes using an aqueous sodium acetate (SA) buffer that can be used to identify clinically relevant Gram-positive and -negative pathogens and fungal species in less than an hour. The SA method also has the ability to differentiate antibiotic-susceptible and antibiotic-resistant strains, directly identify microbes from biological specimens, and detect multiple pathogens in a mixed sample. These results should have positive implications for the manner in which bacteria and fungi are identified in general hospital settings and intensive care units.

Visualizing Microbial Community Dynamics via a Controllable Soil Environment

“…3a and c). Phospholipids are a major constituent of microbial cell membranes (35), and changes in environmental conditions can modulate cell membrane phospholipid composition of microbial communities (36)(37)(38). As such, the most abundant lipids on the chitin islands were signatures of specific microorganisms that grew on chitin under the different moisture regimes (Fig.…”

A Prospective Study of Acinetobacter baumannii Complex Isolates and Colistin Susceptibility Monitoring by Mass Spectrometry of Microbial Membrane Glycolipids

“…Additionally, recent work by our group introduces a novel extraction method that takes less than 1 h and bypasses the overnight lyophilization step without sacrificing spectral quality. This reduces the turnaround time to that of MALDI-TOF ID of microbial proteins, making this platform far more rapid than culture-based diagnostics for species identification and AST (37).…”

Detection of Antibiotic-Resistance by MALDI-TOF Mass Spectrometry: An Expanding Area

“…With another approach focusing on mass spectrometric analysis of membrane lipids, it was demonstrated that bacterial glycolipids possess species-specific characteristics allowing bacterial identification (Leung et al, 2017). Next, a lipidextraction protocol was described (Liang et al, 2019) that reduces the identification time to <1 h. This method has been tested to detect antibiotic-resistance and to identify microbes, without requiring culture, using a library of the clinically relevant ESKAPE pathogens and colistin-resistant pathogens expressing the mcr-1 gene in trans. Different biomarkers of resistance were found: mcr-1-containing P. aeruginosa strains showed a mass shift, 1,446-1,569 m/z, deriving by a PEtN ( m/z 123) addition to lipid A.…”