MAPt: A Rapid Antibiotic Susceptibility Testing for Bacteria in Environmental Samples as a Means for Bioterror Preparedness

Abstract

Antibiotic resistance of bio-threat agents holds major concerns especially in light of advances in methods for engineering pathogens with antibiotic resistance. Preparedness means for rapid identification and prompt proper medical treatment are of need to contain the event and prevent morbidity and spreading of the disease by properly treating exposed individuals before symptoms appearance. Herein, we describe a novel, rapid, simple, specific, and sensitive method named Micro-Agar-PCR-test (MAPt), which determines antibiotic susceptibility of bio-terror pathogens, directly from environmental samples, with no need for any prior isolation, quantification, or enrichment steps. As proof of concept, we have used this approach to obtain correct therapeutic antibiotic minimal inhibitory concentration (MIC) values for the Tier-1 select agents, Bacillus anthracis, Yersinia pestis, and Francisella tularensis, spiked in various environmental samples recapitulating potential bioterror scenarios. The method demonstrated efficiency for a broad dynamic range of bacterial concentrations, both for fast-growing as well as slow-growing bacteria and most importantly significantly shortening the time for accurate results from days to a few hours. The MAPt allows us to address bioterror agents-contaminated environmental samples, offering rational targeted prophylactic treatment, before the onset of morbidity in exposed individuals. Hence, MAPt is expected to provide data for decision-making personal for treatment regimens before the onset of symptoms in infected individuals.

Improved Selective BIN Agar for a Better Rate of Yersinia pestis Isolation from Primary Clinical Specimens in Suspected Madagascar Plague Cases

“…Environmental samples were collected from different areas in Israel and represent vast microbial content, including Bacillus cereus , Bacillus megaterium , Bacillus thuringensis , Bacillus subtilis , Erwinia herbicola , and Pseudomonas aeruginosa , as described in Aloni-Grinstein et al ( 8 ).…”

Beating the Bio-Terror Threat with Rapid Antimicrobial Susceptibility Testing

“…We recently reported on the development of a rapid AST that fulfills all these criteria. The new assay, named MAPt (micro-agar-PCR-test), is based on a micro-agar dilution test followed by a sensitive and specific qPCR step that detects only the target bacteria from all other naturally existing bacteria in the sample thus offering a target MIC value even in a heterologous sample [ 114 ]. Furthermore, agar medium better supports the growth of low bacterial concentrations which could not be reached by using the broth microdilution-based assays thus allowing MIC determination of samples with low bacterial concentrations.…”

“…The assay was applied on various environmental samples, outdoors as well as indoors, spiked with all three Tier-1 agents, with low to high bacterial concentrations, and was found to provide adequate MIC values, such as the ones obtained by the standard AST, albeit at remarkably shorter time frames. Strikingly, this outstanding assay is capable of providing adequate MIC values even when the ratio of the tested bacteria to the naturally occurring environmental bacteria is 1:1 [ 114 ]. Similarly, the reporter-phage AST, was also found to be a potential method for antibiotic susceptibility determination of Y. pestis inoculated environmental samples [ 113 ].…”

“…Similarly, the reporter-phage AST, was also found to be a potential method for antibiotic susceptibility determination of Y. pestis inoculated environmental samples [ 113 ]. To the best of our knowledge these are the first assays that provide such performances, namely, they work even in the presence of bacterial contaminations, thus there is no need for the time-consuming isolation/purification steps [ 114 ]. Moreover, MAPt was shown to be applicable to a wide range of bacterial concentrations.…”

Rapid Antibiotic Susceptibility Testing of Tier-1 Agents Bacillus anthracis, Yersinia pestis, and Francisella tularensis Directly From Whole Blood Samples

“…We have recently reported on a rapid AST, named MAPt (Micro-Agar-PCR-test), which allows one to address bioterror agent-contaminated environmental samples, offering rational targeted prophylactic treatment before the onset of morbidity in exposed individuals (Aloni-Grinstein et al, 2020). As MAPt does not require any enrichment, isolation, or quantification steps, and can be applied even at relatively low concentrations of bacteria, we evaluated its performance on clinical samples, blood cultures, and whole blood samples inoculated with three different Tier-1 agents: B. anthracis, Y. pestis, and F. tularensis.…”