大肠杆菌主动外排泵与抗生素多重耐药性研究进展

细菌对抗生素的耐药性是感染性疾病治疗失败的重要原因之一.细菌可对某类抗菌药物产生耐药性,也可同时对多种化学结构各异的抗菌药物耐药即多重耐药性(Multiple antibiotic resistance 或 Multidrug resistance).细菌多重耐药性可表现在细菌对抗生素的原发耐药性,即细菌固有的天然耐药性(Intrinsic resistance),如常见于革兰阴性细菌及分枝杆菌.细菌也可能通过基因突变等机制进一步提高原有的耐药水平而形成继发耐药性(Acquired resistance).细菌多重耐药性的研究在过去的几年中是颇为活跃的研究领域,有关研究日渐细致深入,并已用于指导新药的开发研制.

Formation of biofilm is a survival strategy for bacteria and fungi to adapt to their living environment, especially in the hostile environment. Under the protection of biofilm, microbial cells in biofilm become tolerant and resistant to antibiotics and the immune responses, which increases the difficulties for the clinical treatment of biofilm infections. Clinical and laboratory investigations demonstrated a perspicuous correlation between biofilm infection and medical foreign bodies or indwelling devices. Clinical observations and experimental studies indicated clearly that antibiotic treatment alone is in most cases insufficient to eradicate biofilm infections. Therefore, to effectively treat biofilm infections with currently available antibiotics and evaluate the outcomes become important and urgent for clinicians. The review summarizes the latest progress in treatment of clinical biofilm infections and scientific investigations, discusses the diagnosis and treatment of different biofilm infections and introduces the promising laboratory progress, which may contribute to prevention or cure of biofilm infections. We conclude that, an efficient treatment of biofilm infections needs a well-established multidisciplinary collaboration, which includes removal of the infected foreign bodies, selection of biofilm-active, sensitive and well-penetrating antibiotics, systemic or topical antibiotic administration in high dosage and combinations, and administration of anti-quorum sensing or biofilm dispersal agents.

The aim of this study was to develop and validate a simple, sensitive, precise and cost-effective one-level agar diffusion (5t1) bioassay for estimation of potency and bioactivity of Levofloxacin in pharmaceutical preparation which has not yet been reported in any pharmacopoeia. Among 16 microbial strains, Bacillus pumilus ATCC-14884 was selected as the most significant strain against Levofloxacin. Bioassay was optimized by investigating several factors such as buffer pH, inoculums concentration and reference standard concentration. Identification of Levofloxacin in commercial sample Levoflox tablet was done by FTIR spectroscopy. Mean potency recovery value for Levofloxacin in Levoflox tablet was estimated as 100.90%. A validated bioassay method showed linearity (r2 ? 0.988), precision (Interday RSD ? 1.05%, between analyst RSD ? 1.02%) and accuracy (101.23%, RSD ? 0.72%). Bioassay was correlated with HPLC using same sample and estimated potencies were 100.90%and 99.37%, respectively. Results show that bioassay is a suitable method for estimation of potency and bioactivity of Levofloxacin pharmaceutical preparations.