Antibiotics selectivity

Monensin, which is one of the natural antibiotics, selectively transports Na+ across an artificial liquid membrane (organic solvent) from the basic aqueous phase (IN) to the acidic aqueous phase (OUT), driven by the proton gradient8). (Fig. 1, 2)... 

Of the fonr possible optical isomers of chloramphenicol, only the o-threo form is active. This antibiotic selectively inhibits protein synthesis in bacterial ribosomes by binding to the 50S subunit in the region of the A site involving the 23 S rRNA. The normal binding of the aminoacyl-tRNA in the A site is affected by chloramphenicol in such a... 

Antibiotic selection is based on periodic culture and sensitivity data, typically covering all organisms identified over the preceding year. If no culture data are available, empiric antibiotics should cover the most likely organisms for the patient s age group. 

Empirical antibiotic selection for acute bacterial rhinosinusitis should incorporate patient risk factors for bacterial resistance. 

If there is a lack of improvement or worsening with initial therapy during the first 48 to 72 hours, antibiotic selection must be reassessed, and other contributing diseases must be excluded5,6 (see Fig. 69-2). Tympanocentesis can help to guide therapy in difficult cases. 

Simon D, Trenholme G. Antibiotic selection for patients with septic shock. Crit Care Clin 2000 16 215-231. 

Coppa GF, Eng K Factors involved in antibiotic selection in elective colon and rectal surgery. Surgery 1988 104 853-858. 

Technically, cDNAs are cloned into plasmids carrying an antibiotic selection marker for propagation in bacteria, a nutritional selection marker for selection of transfected yeast as well as the respective origins of replication. After amplification in bacteria, the plasmids are transfected into the corresponding auxothrophic yeast strain using similar methods as for bacteria and stably... 

Wait at least 24 h after transfection to allow for sufficient expression of the resistance gene before adding antibiotics. Include two plates as controls one plate of transfected cells without antibiotic selection as positive control for cell viability and another plate of untransfected cells, seeded at the same density and treated with blasticidin to monitor cell resistance and antibiotic activity. All cells should die in this control under antibiotic selective pressure. 

Typical classes and examples within these categories as they apply to what is currently most prescribed on the U.S. market are summarized in Table 1.8. The targets in groups 1 and 4 are unique in bacteria and absent in humans and other animals, whereas groups 2, 3, and 5 have human counterparts that are structurally different between prokaryotes and eukaryotes. These differences in targets make the use of antibiotics selective for bacteria with little or no effect on eukaryotic cells from a therapeutic perspective. However, that does not mean that antimicrobial compounds are completely inert to eukaryotes. The mechanisms that block bacterial protein synthesis, block DNA replication, and those that disrupt membrane integrity affect membrane pores. 

Clones with ampicillin resistance but without kanamycin resistance are examined with the CloneChecker System. By this antibiotic selection, the undesired vector heterodimer is removed. If both of the clones are false, additional clones are analyzed using the same protocol. When appropriate clones are obtained for almost all of the genes, they are inoculated from the ampicillin plates to prepare plasmids in a 96-well format by using the Wizard SV 96 Plasmid DNA Purification System see Note 6). 

Kollef MH (2000) Ventilator-associated pneumonia the importance of initial empiric antibiotic selection. Infect Med 17 278-283... 

Pol. mini-Tn5 transposon using lacZ blue/white screen, then delivering the transposon to stable insertion in host chromosome. Another mini-Tn5 provides T7 polymerase inducible by benzoate. Seven different antibiotic selections available to allow multiple genes expressed in same host. ... 

The use of antibiotics in large-scale fermentation is not desirable because of the high production cost. E. coli HMS174 with plasmid pUC19/ CAB showed relatively low instability problems during PHA production in the absence of antibiotic selective pressure when in the flask culture (Table 3). The percentage yield of PHA in cell culture with or without ampicillin was similar. Therefore, it was desirable to subject this strain to a fermentor experiment. 

The selection of transformed cells is achieved using a conferred selectable trait, most commonly antibiotic resistance. Only transformed cells with the conferred resistance trait are able to survive and reproduce. However, the use of antibiotics as a media component for commercial protein production is problematic for at least two reasons. First, residual antibiotic would be a highly undesirable contaminant in the final product. Second, the recurrent use of antibiotics increases the likelihood that antibiotic-resistant pathogen strains will develop. Recent studies indicate that antibiotic selection is not necessary during every passage (or generation). 

Many principles of antibiotic selection are illustrated by this patient. (1) His history of serious allergy to penicillin eliminated this entire family of antibiotics from consideration. Thus, when his dental abscess... 

Over several decades, multiple vector systems for recombinant gene expression in E. coli have been developed. Modem vectors suitable for recombinant protein production vary in the used promoter system in the presence or absence of coding sequences for affinity tags upstream or downstream of the multiple cloning site (MCS) and of sequences coding for leader peptides for the protein export. Moreover, different origins of replication (ori), antibiotic selection marker genes and MCS are used. 

Roth DB, Flynn HW. Antibiotic selection in the treatment of endophthalmitis the significance of drug combinations and synergy. Surv Ophthalmol 1997 41 395-401. 

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