Evolution of Antibiotic Resistance in Surrogates of Francisella tularensis (LVS and Francisella novicida ): Effects on Biofilm Formation and Fitness.

Autor:	Biot FV; Institut de Recherche Biomédicale des Armées, Département de Biologie des Agents Transmissibles, Unité de Bactériologie/UMR_MD1, Brétigny-sur-Orge, France., Bachert BA; Bacteriology Division, U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID), Frederick, MD, United States., Mlynek KD; Bacteriology Division, U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID), Frederick, MD, United States., Toothman RG; Bacteriology Division, U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID), Frederick, MD, United States., Koroleva GI; Center for Genome Sciences, U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID), Frederick, MD, United States., Lovett SP; Center for Genome Sciences, U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID), Frederick, MD, United States., Klimko CP; Bacteriology Division, U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID), Frederick, MD, United States., Palacios GF; Center for Genome Sciences, U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID), Frederick, MD, United States., Cote CK; Bacteriology Division, U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID), Frederick, MD, United States., Ladner JT; Center for Genome Sciences, U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID), Frederick, MD, United States., Bozue JA; Bacteriology Division, U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID), Frederick, MD, United States.
Jazyk:	angličtina
Zdroj:	Frontiers in microbiology [Front Microbiol] 2020 Oct 30; Vol. 11, pp. 593542. Date of Electronic Publication: 2020 Oct 30 (Print Publication: 2020).
DOI:	10.3389/fmicb.2020.593542
Abstrakt:	Francisella tularensis , the causative agent of tularemia, is capable of causing disease in a multitude of mammals and remains a formidable human pathogen due to a high morbidity, low infectious dose, lack of a FDA approved vaccine, and ease of aerosolization. For these reasons, there is concern over the use of F. tularensis as a biological weapon, and, therefore, it has been classified as a Tier 1 select agent. Fluoroquinolones and aminoglycosides often serve as the first line of defense for treatment of tularemia. However, high levels of resistance to these antibiotics has been observed in gram-negative bacteria in recent years, and naturally derived resistant Francisella strains have been described in the literature. The acquisition of antibiotic resistance, either natural or engineered, presents a challenge for the development of medical countermeasures. In this study, we generated a surrogate panel of antibiotic resistant F. novicida and Live Vaccine Strain (LVS) by selection in the presence of antibiotics and characterized their growth, biofilm capacity, and fitness. These experiments were carried out in an effort to (1) assess the fitness of resistant strains; and (2) identify new targets to investigate for the development of vaccines or therapeutics. All strains exhibited a high level of resistance to either ciprofloxacin or streptomycin, a fluoroquinolone and aminoglycoside, respectively. Whole genome sequencing of this panel revealed both on-pathway and off-pathway mutations, with more mutations arising in LVS. For F. novicida , we observed decreased biofilm formation for all ciprofloxacin resistant strains compared to wild-type, while streptomycin resistant isolates were unaffected in biofilm capacity. The fitness of representative antibiotic resistant strains was assessed in vitro in murine macrophage-like cell lines, and also in vivo in a murine model of pneumonic infection. These experiments revealed that mutations obtained by these methods led to nearly all ciprofloxacin resistant Francisella strains tested being completely attenuated while mild attenuation was observed in streptomycin resistant strains. This study is one of the few to examine the link between acquired antibiotic resistance and fitness in Francisella spp., as well as enable the discovery of new targets for medical countermeasure development. (Copyright © 2020 Biot, Bachert, Mlynek, Toothman, Koroleva, Lovett, Klimko, Palacios, Cote, Ladner and Bozue.)
Databáze:	MEDLINE
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