Novel antibacterial agents for the treatment of serious Gram-positive infections

With the continuing development of clinical drug resistance among bacteria and the advent of resistance to the recently released agents quinupristin-dalfopristin and linezolid, the need for new, effective agents to treat multi-drug-resistant Gram-positive infections remains important. This review focuses on agents presently in clinical development for the treatment of serious multidrug-resistant staphylococcal, enterococcal and pneumococcal infections, including methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci and penicillin-resistant Streptococcus pneumoniae. Agents to be discussed that affect the prokaryotic cell wall include the antimethicillin-resistant S. aureus cephalosporins BAL9141 and RWJ-54428, the glycopeptides oritavancin and dalbavancin and the lipopeptide daptomycin. Topoisomerase inhibitors include the fluoroquinolones gemifloxacin, sitafloxacin and garenoxacin. Protein synthesis inhibitors are represented by the ketolides telithromycin and cethromycin, the oxazolidinones and the glycylcycline tigecycline. Although each of these compounds has demonstrated antibacterial activity against antibiotic-resistant pathogens, their final regulatory approval will depend on an acceptable clinical safety profile.     

Quantitative assessment of the hepatic pharmacokinetics of the antimicrobial sitafloxacin in humans using in vivoF magnetic resonance spectroscopy

AIMS: To measure hepatic concentrations of the fluorine-containing antimicrobial, sitafloxacin, using in vivo(19)F magnetic resonance spectroscopy (MRS). METHODS: Data were acquired from eight healthy subjects at 2, 5, 8 and 24 h following doses of 500 mg day(-1) for 5 days using a (1)H/(19)F surface coil in a 1.5T clinical MR system. Tissue water was used as a reference. RESULTS: Estimated liver concentrations at 2 h were 15.0 +/- 4.0 microg ml(-1) (mean +/- 95% CI), compared with 3.54 +/- 0.58 microg ml(-1) in plasma (n = 6), and fell below threshold concentrations (2 microg ml(-1)) by 24 h. CONCLUSIONS: (19)F MRS is able to detect and quantify sitafloxacin in the liver. There was no evidence for the hepatic retention of the drug.     

西他沙星治疗幽门螺杆菌感染的研究进展

西他沙星为2008年在日本获批上市的新型喹诺酮类药,多年来在日本被推荐用于幽门螺杆菌(Hp)感染患者的补救方案.西他沙星于2019年在中国获批上市,为我国Hp感染患者的治疗提供了新的选择.研究发现在抗菌药物耐药性不断增加的情况下,西他沙星可作为较好的替代抗菌药物用于治疗Hp感染.     

‘Superbugs’: new antibacterials in the pipeline

‘Superbugs’ in the context discussed herein are Gram-positive pathogens that are multi-resistant to common antibiotic classes. Although many of these organisms were recently susceptible only to vancomycin, therapeutic options are now expanding with the recent approvals for the use of quinupristin-dalfopristin and linezolid against some of these pathogens. Compounds currently under development include cell-wall active agents, such as anti-MRSA cephalosporins, and the glycopeptide LY-333328 to treat resistant Gram-positive infections. More active topoisomerase inhibitors, such as gemifloxacin, sitafloxacin and non-fluoroquinolones, are being evaluated for treatment of multi-drug resistant streptococci, as is the penem faropenem. Novel protein synthesis inhibitors, such as new ketolides and the glycylcycline GAR-936, are also in development; in addition, the lipopeptides daptomycin and HMR-1043 are being evaluated. Safety and efficacy in the treatment of serious infections are two major issues that will determine the eventual success of these agents.     

毛细管电泳手性拆分西他沙星异构体

目的:建立西他沙星及其异构体高效毛细管电泳拆分的新方法。方法:以β-环糊精及几种环糊精衍生物作为手性添加剂,采用毛细管电泳分离新型抗菌素西他沙星与其3个异构体。对运行缓冲液的浓度、pH,环糊精的种类、二元环糊精体系中环糊精的比例,分离电压,柱温,有机改性剂等因素对分离的影响进行考察,并对拆分机制进行初步探讨。结果:运行缓冲液为含2%硫酸化-β-环糊精和1%β-环糊精的25 mmol.L-1的磷酸二氢钾-磷酸缓冲溶液(pH 2.5),操作电压为-25kV,柱温为25℃,检测波长为295 nm,西他沙星与其3个异构体达到良好分离。结论:所建立的毛细管电泳方法简便,适用于西他沙星异构体的检查。     

西他沙星关键中间体胺基氮杂螺环的不对称合成

7-(S)-(叔丁氧羰基胺基)-5-氮杂螺［2.4］庚烷是合成新一代喹诺酮类抗生素西他沙星和欧拉沙星的关键中间体,但现有合成方法收率低、立体选择性较差。本研究对其合成工艺进行了改进,开发了一种新的不对称合成方法,反应的收率和立体选择性得到了明显提高,且原料易得,步骤短,所得手性异构体光学纯度高。     

A randomized controlled trial (volunteer study) of sitafloxacin, enoxacin, levofloxacin and sparfloxacin phototoxicity

BACKGROUND: Fluoroquinolone antibiotics (FQs) are associated with phototoxic skin reactions following exposure to sunlight. OBJECTIVES: We aimed to compare the phototoxic potential of sitafloxacin, a novel FQ with three others: sparfloxacin, enoxacin, levofloxacin and placebo in Caucasian volunteers. In a second study, two dosage regimens of sitafloxacin were compared with placebo in Oriental subjects. METHODS: Randomized, placebo-controlled, assessor-blinded clinical trial. In 40 healthy Caucasians, sitafloxacin 100 mg twice a day (n = 8), sparfloxacin 200 mg day-1 (n = 8), enoxacin 200 mg three times a day (n = 8), levofloxacin 100 mg three times a day (n = 8) and placebo (n = 8) were given in oral doses for 6 days. In the second study, sitafloxacin 50 mg and 100 mg, both twice daily, were compared with placebo in 17 healthy Oriental subjects. Using an established monochromator technique, baseline threshold erythema levels were established pre-drug and on-drug. The phototoxic index (PI) baseline, minimal erythema dose (MED) divided by on-drug MED for each medication at each wavelength was determined and related to sitafloxacin peak plasma levels. The duration of susceptibility to phototoxicity was assessed by repeat phototesting daily after stopping medication. RESULTS: In the Caucasian study, sitafloxacin 100 mg twice a day produced mild ultraviolet (UV) A-dependent phototoxicity (median PI = 1.45) at 365 +/- 30 nm (half-maximum bandwidth), maximal at 24 h with normalization by 24 h postdrug cessation. The sparfloxacin group experienced severe phototoxicity maximal at 24 h and, unusually for an FQ, extended in the visible region (430 +/- 30 nm), maximal at 400 +/- 30 nm (median PI = 12.35) with abnormal pigmentation at on-drug phototest sites lasting, although fading, for up to 1 year. Enoxacin showed UVA-dependent phototoxicity (335-365 +/- 30 nm) median PI 3.94 (at 365 +/- 30 nm) returning to normal 48 h after stopping the drug. Fading pigmentation at phototoxic sites also lasted up to 1 year. Phototoxicity was not detected in the levofloxacin or placebo groups. In the Oriental study, no clinically relevant phototoxicity was seen with either sitafloxacin or placebo groups. CONCLUSIONS: We conclude that 100 mg twice a day sitafloxacin in Caucasians is associated with a mild degree of cutaneous phototoxicity. Enoxacin 200 mg three times a day and sparfloxacin 200 mg day-1 are much more photoactive. Sparfloxacin phototoxicity is induced by UVA and visible wavelengths. Levofloxacin and placebo failed to show a phototoxic effect. In the Oriental study, sitafloxacin 50 mg twice a day and 100 mg twice a day failed to demonstrate a clinically significant phototoxic effect.     

Prognosis of chronic pulmonary aspergillosis in patients with pulmonary non-tuberculous mycobacterial disease

Background

Pulmonary non-tuberculous mycobacterial disease (PNTM) is a known risk factor for chronic pulmonary aspergillosis (CPA). However, few studies have focused on the prognosis of PNTM-associated CPA. In the present investigation, we aimed to elucidate the clinical course and prognostic factors of CPA in patients with PNTM.