A rapid real-time quantitative PCR assay to determine the minimal inhibitory extracellular concentration of antibiotics against an intracellular Francisella tularensis Live Vaccine Strain
Ronit Aloni-Grinstein, Ohad Shifman, Shlomi Lazar, Ida Steinberger-Levy, Sharon Maoz, Raphael Ber
Abstract
Francisella tularensis is a highly virulent facultative intracellular bacterium. The lack of a safe and efficient vaccine makes antibiotics the preferred treatment. F. tularensis antibiotic susceptibility tests are based on the in vitro standard CLSI-approved microdilution method for determining the MIC. However, limited data are available regarding the minimal inhibitory extracellular concentration (MIEC) needed to eradicate intracellular bacteria. Here, we evaluated the MIEC values of various WHO-recommended antibiotics and compared the MIEC values to the established MICs. We describe a rapid 3-h quantitative PCR (qPCR) intracellular antibiogram assay, which yields comparable MIEC values to those obtained by the classical 72-h cfu assay. This rapid qPCR assay is highly advantageous in light of the slow growth rates of F. tularensis. Our results showed that the MIECs obtained for doxycycline, chloramphenicol and ciprofloxacin were indicative of intracellular activity. Gentamicin was not effective against intracellular bacteria for at least 32 h post treatment, raising the question of whether slow-penetrating gentamicin should be used for certain stages of the disease. We suggest that the qPCR intracellular antibiogram assay may be used to screen for potentially active antibiotics against intracellular F. tularensis as well as to detect strains with acquired resistance to recommended antibiotics.
This research output has an Altmetric Attention Score of 2. This is our high-level measure of the quality and quantity of online attention that it has received. This Attention Score, as well as the ranking and number of research outputs shown below, was calculated when the research output was last mentioned on 20 November 2015.
All research outputs
#13,958,483
of 22,832,057 outputs
Outputs from Frontiers in Microbiology
#11,421
of 24,806 outputs
Outputs of similar age
#142,716
of 285,121 outputs
Outputs of similar age from Frontiers in Microbiology
#185
of 435 outputs
Altmetric has tracked 22,832,057 research outputs across all sources so far. This one is in the 37th percentile – i.e., 37% of other outputs scored the same or lower than it.
So far Altmetric has tracked 24,806 research outputs from this source. They typically receive a little more attention than average, with a mean Attention Score of 6.3. This one has gotten more attention than average, scoring higher than 50% of its peers.
Older research outputs will score higher simply because they've had more time to accumulate mentions. To account for age we can compare this Altmetric Attention Score to the 285,121 tracked outputs that were published within six weeks on either side of this one in any source. This one is in the 48th percentile – i.e., 48% of its contemporaries scored the same or lower than it.
We're also able to compare this research output to 435 others from the same source and published within six weeks on either side of this one. This one has gotten more attention than average, scoring higher than 52% of its contemporaries.
