Evaluation of Combination Drug Therapy for Treatment of Antibiotic-Resistant Inhalation Anthrax in a Murine Model.

Bacillus anthracis is considered a likely agent to be used as a bioweapon, and the use of a strain resistant to the first-line antimicrobial treatments is a concern. We determined treatment efficacies against a ciprofloxacin-resistant strain of B. anthracis (Cipr Ames) in a murine inhalational anthrax model. Ten groups of 46 BALB/c mice were exposed by inhalation to 7 to 35 times the 50% lethal dose (LD50) of B. anthracis Cipr Ames spores. Commencing at 36 h postexposure, groups were administered intraperitoneal doses of sterile water for injections (SWI) and ciprofloxacin alone (control groups), or ciprofloxacin combined with two antimicrobials, including meropenem-linezolid, meropenem-clindamycin, meropenem-rifampin, meropenem-doxycycline, penicillin-linezolid, penicillin-doxycycline, rifampin-linezolid, and rifampin-clindamycin, at appropriate dosing intervals (6 or 12 h) for the respective antibiotics. Ten mice per group were treated for 14 days and observed until day 28. The remaining animals were euthanized every 6 to 12 h, and blood, lungs, and spleens were collected for lethal factor (LF) and/or bacterial load determinations. All combination groups showed significant survival over the SWI and ciprofloxacin controls: meropenem-linezolid (P = 0.004), meropenem-clindamycin (P = 0.005), meropenem-rifampin (P = 0.012), meropenem-doxycycline (P = 0.032), penicillin-doxycycline (P = 0.012), penicillin-linezolid (P = 0.026), rifampin-linezolid (P = 0.001), and rifampin-clindamycin (P = 0.032). In controls, blood, lung, and spleen bacterial counts increased to terminal endpoints. In combination treatment groups, blood and spleen bacterial counts showed low/no colonies after 24-h treatments. The LF fell below the detection limits for all combination groups yet remained elevated in control groups. Combinations with linezolid had the greatest inhibitory effect on mean LF levels.

Human anthrax outbreak associated with livestock exposure: Georgia, 2012.

Human anthrax cases reported in the country of Georgia increased 75% from 2011 (n = 81) to 2012 (n = 142). This increase prompted a case-control investigation using 67 culture- or PCR-confirmed cases and 134 controls matched by residence and gender to investigate risk factor(s) for infection during the month before case onset. Independent predictors most strongly associated with disease in the multivariable modelling were slaughtering animals [odds ratio (OR) 7·3, 95% confidence interval (CI) 2·9-18·1, P 1 km; 15 (12%) of 125 had sick livestock; and 11 (9%) of 128 respondents reported finding dead livestock. We recommend joint public health and veterinary anthrax case investigations to identify areas of increased risk for livestock anthrax outbreaks, annual anthrax vaccination of livestock in those areas, and public awareness education.

Review of brucellosis cases from laboratory exposures in the United States in 2008 to 2011 and improved strategies for disease prevention.

Five laboratory-acquired brucellosis (LAB) cases that occurred in the United States between 2008 and 2011 are presented. The Centers for Disease Control and Prevention (CDC) reviewed the recommendations published in 2008 and the published literature to identify strategies to further prevent LAB. The improved prevention strategies are described.

Phosphoprotein profile analysis of ruminant respiratory syncytial virus isolates.

OBJECTIVE: To determine the apparent molecular weight for 24 ruminant respiratory syncytial viruses (RSV) on the basis of differences in the electrophoretic mobility of the phosphoprotein (P protein). PROCEDURE: 29 bovine RSV (BRSV), 20 of which were not previously tested, 3 ovine RSV, and 1 caprine RSV isolates were selected for determination of electrophoretic mobility of the P protein. Virus radiolabeled with [35S]methionine was immunoprecipitated with polyclonal antiserum to BRSV and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. RESULTS: On the basis of apparent molecular size of the P protein, all isolates could be categorized into 2 electropherotypes, low molecular size of 36 kd and high molecular size of 38 kd. Twenty-three BRSV, the 3 ovine RSV, and 1 caprine RSV isolates had a high molecular size P protein; 6 BRSV isolates had a low molecular size P protein. CONCLUSIONS: The apparent molecular size of the P protein of the ruminant RSV strains is greater than that of the human RSV subgroups, providing further evidence of their distinctiveness. Whether categorization of electrophoretic mobility of the P protein of BRSV underlies distinct antigenic subgroups, as it does in human RSV, requires further antigenic and genetic analysis. CLINICAL RELEVANCE: Antigenic subgroups of ruminant RSV may have relevance in the development of new vaccines for control of the disease.