Effective methods for the inactivation of Francisella tularensis

• Published in: PloS one Vol. 14; no. 11; p. e0225177
• Main Authors: Azaki, Mika, Uda, Akihiko, Tian, Deyu, Nakazato, Katsuyoshi, Hotta, Akitoyo, Kawai, Yasuhiro, Ishijima, Keita, Kuroda, Yudai, Maeda, Ken, Morikawa, Shigeru
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 14.11.2019; Public Library of Science (PLoS)
• Subjects: Acetone; Analysis; Bacteria; Biology and Life Sciences; Biosafety; Deactivation; Detergents; Diagnostic reagents industry; Disease control; Disease prevention; Engineering and Technology; Ethanol; Fighter planes; Filtration; Francisella tularensis; Heat treatment; Inactivation; Infections; Infectious diseases; Laboratories; Lithium; Medical research; Medicine and Health Sciences; Methods; Microbiology; Mortality; Organic chemistry; Physical Sciences; Radiation (Physics); Radiation tolerance; Research and Analysis Methods; Researchers; Strains (organisms); Sulfates; Surface active agents; Tubes; Ultraviolet radiation; Veterinary medicine; United States; Japan; Beijing China; United States > US; Tokyo Japan; China
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0225177

Francisella tularensis (F. tularensis) is highly pathogenic to humans and must be handled under biosafety level 3 conditions. Samples used for the diagnosis and experimental analysis must be completely inactivated, although methods for the inactivation of F. tularensis are limited. In this study, effective methods for the inactivation of F. tularensis SCHU P9 and five other strains were determined by comparisons of colony-forming units between treated and control samples. The results showed that F. tularensis SCHU P9 was denatured by heat treatment (94°C for 3 min and 56°C for 30 min), filtration with a 0.22 μm filter, and the use of various solutions (i.e. >70% ethanol, methanol, acetone, and 4% paraformaldehyde). F. tularensis SCHU P9 remained viable after treatment with 50% ethanol for 1 min, filtration with a 0.45 μm filter, and treatments with detergents (i.e. 1% lithium dodecyl sulfate buffer, 1% Triton X-100 and 1% Nonidet P-40) at 4°C for 24 h. Additionally, F. tularensis SCHU P9 suspended in fetal bovine serum in plastic tubes was highly resistant to ultraviolet radiation compared to suspensions in water and chemically defined medium. The methods for inactivation of F. tularensis SCHU P9 was applicable to the other five strains of F. tularensis. The data presented in this study could be useful for the establishment of guidelines and standard operating procedures (SOP) to inactivate the contaminated samples in not only F. tularensis but also other bacteria.