Intracellular Activity of Antibiotics against Coxiella burnetii in a Model of Activated Human THP-1 Cells.

We evaluated antibiotic activity against the intracellular bacterium Coxiella burnetii using an activated THP-1 cell model of infection. At clinically relevant concentrations, the intracellular bacterial load was reduced 300-fold by levofloxacin and finafloxacin, 40-fold by doxycycline, and 4-fold by ciprofloxacin and was unaffected by azithromycin. Acidification of the culture medium reduced antibiotic activity, with the exceptions of doxycycline (no change) and finafloxacin (slight improvement). This model may be used to select antibiotics to be evaluated in vivo.

Evaluation of two multiplex real-time PCR screening capabilities for the detection of Bacillus anthracis, Francisella tularensis and Yersinia pestis in blood samples generated from murine infection models.

Two multiplex PCR screening capabilities (TaqMan Array Cards and FilmArray) were evaluated for their ability to detect Bacillus anthracis, Francisella tularensis and Yersinia pestis in blood samples obtained from respective murine infection models. Blood samples were obtained from infected mice at 24 h intervals after exposure. Multiplex PCR results were compared with standard blood culture and singleplex real-time PCR. Across all three models, 71 mice were tested in total, within which a subset of 43 samples was shown to contain an infecting agent by at least one of the detection technologies. Within this subset of positive samples, for each model studied, the detection rates of each technology were compared. The B. anthracis model blood culture (14 of 15 agent-containing samples tested) and FilmArray PCR (12 of 15) were shown to have equivalent detection rates, which were significantly higher (at the 95 % confidence level) than singleplex (five of 14) or Array Card (two of 14) PCRs. The F. tularensis model blood culture (12 of 12) was shown to have a significantly higher (at 95 % confidence level) detection rate than all PCR technologies, with FilmArray (seven of 11) and singleplex (seven of 12) PCRs shown to have significantly higher (at 95 % confidence level) detection rates than the Array Card PCR (two of 11). Within the Y. pestis model, there was no significant difference in detection rates between blood culture (10 of 16), singleplex PCR (14 of 16), Array Card PCR (10 of 16) and FilmArray PCR (10 of 13).