Evaluation of the relationship between the Adenosine Triphosphate (ATP) bioluminescence assay and the presence of Bacillus anthracis spores and vegetative cells.

Shawn Gibbs,Harlan Sayles,Erica Colbert,Oleg Chaika,Philip Smith,Angela Hewlett

doi:10.3390/ijerph110605708

Abstract

Background: The Adenosine triphosphate (ATP) bioluminescence assay was utilized in laboratory evaluations to determine the presence and concentration of vegetative and spore forms of Bacillus anthracis Sterne 34F2. Methods: Seventeen surfaces from the healthcare environment were selected for evaluation. Surfaces were inoculated with 50 µL of organism suspensions at three concentrations of 104, 106, 108 colony forming units per surface (CFU/surface) of B. anthracis. Culture-based methods and ATP based methods were utilized to determine concentrations. Results: When all concentrations were evaluated together, a positive correlation between log-adjusted CFU and Relative Light Units (RLU) for endospores and vegetative cells was established. When concentrations were evaluated separately, a significant correlation was not demonstrated. Conclusions: This study demonstrated a positive correlation for ATP and culture-based methods for the vegetative cells of B. anthracis. When evaluating the endospores and combining both metabolic states, the ATP measurements and CFU recovered did not correspond to the initial concentrations on the evaluated surfaces. The results of our study show that the low ATP signal which does not correlate well to the CFU results would not make the ATP measuring devises effective in confirming contamination residual from a bioterrorist event.

Highlights

Bacillus anthracis, a Gram-positive, spore forming, rod shaped bacterium, exists in the environment in two states, as metabolically active vegetative cells or as dormant endospores
We recorded both actual and adjusted concentration of Relative Light Units (RLU) and Colony Forming Units (CFU) per surface evaluated, which allowed the comparison despite variations within each of the organism suspension (Table 2)
The results showed a positive correlation between the log-adjusted CFU and RLU for both endospores (Figure 1a) and vegetative cells (Figure 1b)

Summary

Introduction

A Gram-positive, spore forming, rod shaped bacterium, exists in the environment in two states, as metabolically active vegetative cells or as dormant endospores. The vegetative cells will undergo sporulation to promote the formation of environmentally stable spores. These resistant spores can persist in the environment for months to years, until favorable growth conditions are met again [1]. Due to this ability to undergo sporulation, and the characteristics of being a mesophilic, facultative anaerobe, B. anthracis can be found in soils worldwide [2]. The Adenosine triphosphate (ATP) bioluminescence assay was utilized in laboratory evaluations to determine the presence and concentration of vegetative and spore forms of Bacillus anthracis Sterne 34F2.

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Conclusion