Elucidation of the Mode of Action of a New Antibacterial Compound Active against Staphylococcus aureus and Pseudomonas aeruginosa.

Nosocomial and community-acquired infections caused by multidrug resistant bacteria represent a major human health problem. Thus, there is an urgent need for the development of antibiotics with new modes of action. In this study, we investigated the antibacterial characteristics and mode of action of a new antimicrobial compound, SPI031 (N-alkylated 3, 6-dihalogenocarbazol 1-(sec-butylamino)-3-(3,6-dichloro-9H-carbazol-9-yl)propan-2-ol), which was previously identified in our group. This compound exhibits broad-spectrum antibacterial activity, including activity against the human pathogens Staphylococcus aureus and Pseudomonas aeruginosa. We found that SPI031 has rapid bactericidal activity (7-log reduction within 30 min at 4x MIC) and that the frequency of resistance development against SPI031 is low. To elucidate the mode of action of SPI031, we performed a macromolecular synthesis assay, which showed that SPI031 causes non-specific inhibition of macromolecular biosynthesis pathways. Liposome leakage and membrane permeability studies revealed that SPI031 rapidly exerts membrane damage, which is likely the primary cause of its antibacterial activity. These findings were supported by a mutational analysis of SPI031-resistant mutants, a transcriptome analysis and the identification of transposon mutants with altered sensitivity to the compound. In conclusion, our results show that SPI031 exerts its antimicrobial activity by causing membrane damage, making it an interesting starting point for the development of new antibacterial therapies

Advanced Multiplex PCR Assay for Differentiation of Brucella Species▿

Two new primer sets of a 766- and a 344-bp fragment were introduced into the conventional Bruce-ladder PCR assay. This novel multiplex PCR assay rapidly and concisely discriminates Brucella canis and Brucella microti from Brucella suis strains and also may differentiate all of the 10 Brucella species

Brucella: potential biothreat agent

Brucellosis is an ancient disease caused by brucellae, which are small, facultative, intracellular, gram-negative coccobacilli. Ten species of Brucella have been identified as the causative agents of brucellosis in mammalian hosts. Natural infections with Brucellae occur globally among humans and animals, resulting in significant economic losses. Research in recent years has focused on appropriate methods for environmental sampling, early detection techniques, decontamination procedures, and the development of new therapeutics and vaccines. Despite this research focus, there is still no human vaccine available. This is of particular concern as Brucellae are highly infectious via the aerosol route; therefore, they have the potential to be misused as agents of biological warfare. The global biological terrorist risk is increasing yearly due to a number of factors including increased migration, escalating numbers of displaced people, the speed and scale of global travel, and technological advances which have enhanced our ability to manipulate pathogens. Presented are a review of the recent developments in brucellosis research and an evaluation of the risks associated with the use of brucellae in deliberate biological attacks