RESUMO
The widespread emergence of antibiotic-resistant bacteria and a lack of new pharmaceutical development have catalyzed a need for new and innovative approaches for antibiotic drug discovery. One bottleneck in antibiotic discovery is the lack of a rapid and comprehensive method to identify compound mode of action (MOA). Since a hallmark of antibiotic action is as an inhibitor of essential cellular targets and processes, we identify a set of 308 essential genes in the clinically important pathogen Staphylococcus aureus. A total of 446 strains differentially expressing these genes were constructed in a comprehensive platform of sensitized and resistant strains. A subset of strains allows either target underexpression or target overexpression by heterologous promoter replacements with a suite of tetracycline-regulatable promoters. A further subset of 236 antisense RNA-expressing clones allows knockdown expression of cognate targets. Knockdown expression confers selective antibiotic hypersensitivity, while target overexpression confers resistance. The antisense strains were configured into a TargetArray in which pools of sensitized strains were challenged in fitness tests. A rapid detection method measures strain responses toward antibiotics. The TargetArray antibiotic fitness test results show mechanistically informative biological fingerprints that allow MOA elucidation.
Assuntos
Antibacterianos/farmacologia , Regulação Bacteriana da Expressão Gênica/genética , Genes Essenciais/genética , Staphylococcus aureus/genética , Regulação Bacteriana da Expressão Gênica/efeitos dos fármacos , RNA Antissenso/genética , Staphylococcus aureus/efeitos dos fármacosRESUMO
BACKGROUND: Esomeprazole sodium (Nexium IV, AstraZeneca) is the S-isomer of omeprazole and acts as a proton pump inhibitor gastric antisecretory agent indicated for the short-term treatment of gastroesophageal reflux disease in patients with a history of erosive esophagitis. Currently, there is no information on the long-term stability of esomeprazole sodium in infusion solutions beyond 12 hours. OBJECTIVE: To evaluate the stability of esomeprazole sodium in 5% dextrose, 0.9% sodium chloride, and lactated Ringer's injection, at 2 concentrations, at room temperature and when refrigerated. METHODS: Triplicate samples of esomeprazole 0.4 and 0.8 mg/mL as the sodium salt were prepared in the solutions required. Stability evaluations were performed initially, over 2 days stored at 23 degrees C, and over 5 days stored at 4 degrees C. Physical stability was assessed using turbidimetric and particulate measurement, as well as visual observation. Chemical stability was evaluated by stability-indicating high-performance liquid chromatography. RESULTS: The samples in all 3 infusion solutions were physically stable throughout the study. None of the samples had evidence of visible haze or particulates. Most samples developed a slight yellow discoloration within 24 hours, but this discoloration was not accompanied by an excessive loss of drug content. The esomeprazole sodium samples in all 3 infusion solutions exhibited less than 7% loss over 2 days at 23 degrees C and over 5 days at 4 degrees C. CONCLUSIONS: Esomeprazole 0.4 and 0.8 mg/mL as the sodium salt in the infusion solutions tested is chemically and physically stable for at least 2 days at room temperature and 5 days under refrigeration.