ABSTRACT
The bactericidal mechanism of carbon monoxide (CO) and the feasibility of CO-releasing molecules as anti-infective drugs were summarized by consulting scientific literature, combined with our own research work. Anaerobic bacteria are usually tolerant to high concentration of CO, and some can even grow with CO as sole carbon or energy source, but most pathogenic bacteria are sensitive to CO. In view of the difficulty of gaseous CO in controlling the applying dose and the action site, CO release molecules were synthesized. CO release molecules not only have higher bactericidal activities against common pathogenic bacteria than gaseous CO, but also have the ability to kill antibiotics-resistant bacteria and destroy their biofilms. CO mainly binds with heme-Fe2+ in cells, interrupting the electron transfer of respiration chains, which would result in the generation of reactive oxygen species. CO can also disturb intracellular ion balance, which further triggers free radical reactions. Due to its diverse acting targets, uneasy to induce drug resistance, and synergistic effect with other antibiotics, CO is expected to be the next generation of anti-infection drugs.
ABSTRACT
To introduce peptidoglycan recycling and the β-lactams resistance mechanisms of bacteria, so that some help would be supplied to corresponding scientific workers and university teachers. By searching literatures, combined with our own studies, the bactericidal mechanisms of β-lactams and the resistance mechanisms of bacteria to β-lactams were summarized. The bactericidal activity of β-lactams is resulted from the inhibition of cell wall biosynthesis through combination with penicillin binding proteins such as transpeptidase destruction of peptidoglycan balances between biosynthesis and hydrolysis. The drug resistance of bacteria is resulted from the induction of β-lactamase, expression of out-pumping proteins, increase of outmembrane permeability, and modification of antibiotic target proteins. The proteins related to peptidoglycan recycling, such as transpeptidase and glycosyltransferase, would be potential targets for screening new β-lactams. The proteins related to β-lactams resistance, such as β-lactamase, would be potential targets for screening adjuvant drugs of β-lactams.
ABSTRACT
<p><b>AIMS</b>To screen for the predominant bacteria strains distributed in clean rooms and to analyze their phylogenetic relationships.</p><p><b>METHODS AND RESULTS</b>The bacteria distributed in air, surfaces and personnel in clean rooms were routinely monitored using agar plates. Five isolates frequently isolated from the clean rooms of an aseptic pharmaceutical production workshop were selected based on their colony and cell morphology characteristics. Their physiological and biochemical properties, as well as partial 16S rDNA sequences, were analyzed. Results showed that all the five isolates belong to Gram positive bacteria, of which three were Staphylococcus, one Microbacterium and one Bacillus species. Sensitivity tests for these bacteria isolates to 3 disinfectants showed that isolate F03 was obtuse, and had low susceptivity to UV irradiation, while isolates F02, F01 and F04 were not sensitive to phenol treatment. Isolates F04, F01 and F05 were resistant to chlorhexidine gluconate.</p><p><b>CONCLUSION</b>Bacteria widely distributed in clean rooms are mainly a group of Gram positive strains, showing high resistance to selected disinfectants.</p><p><b>SIGNIFICANCE AND IMPACT OF THE STUDY</b>Clean rooms are essential in aseptic pharmaceutical and food production. Screening bacteria isolates and identifying them is part of good manufacturing practices, and will aid in finding a more effective disinfection method.</p>