Antibiotic resistance phenotypic

Over the last years, a renewed interest on the antibiotic resistance phenotypes in municipal waste water treatment plants became apparent in the scientific literature. The underlying hypothesis of these smdies is that urban sewage treatment plants are potential reservoirs of antibiotic resistance, and, in general, it is aimed at contributing to assess the risks of dissemination, posed by the treated effluents discharged into natural water courses. As a general trend, these studies focus on human/animal commensal and environmental bacteria, frequently disseminated via faecal contamination, and which can survive in waters. The relevance of these bacteria, which may exhibit clinically relevant resistance phenotypes, as possible nosocomial agents seems also to be a motivation behind these smdies. 

I Selection of host cells with Recombinant DNA via f acquisition of antibiotic resistant phenotype... 

K. Bronstad, K. Dronen, L. Ovreas, and V. Torsvick, Phenotypic diversity and antibiotic resistance in soil bacterial communities, J. Ind. Microbiol. 77 253 (1996). 

Phenotypic resistance assays directly measure the ability of HlV-1 to replicate in a cell culture in the presence of different antiretroviral drug concentrations. This process is similar to that used to determine antibiotic resistance and is, therefore, more familiar to most clinicians. The recombinant virus, composed of a virus s reverse transcripfase and protease genes, is inserted into a standard reference strain of virus. The recombinant virus is then tested in vitro for fhe amount of drug needed to inhibit virus replication by 50%, relative to the amount of drug needed to inhibit a reference strain of virus. Phenotypic resistance testing is limited by the fact that it is conducted in vitro and not in vivo. 

Although host defense peptide resistance has remained rare within microbes, concerns have been raised regarding the potential for clinical applications of peptides to provoke peptide-resistant phenotypes. Indeed, the introduction of antibiotics as novel microbial eradicators was met almost instantaneously with bacteria that had manifested various forms of resistance. Thus, precautions should be taken with potential therapeutic application of host defense peptides to minimize similar resistance as seen with antibiotics. Many bacterial species rely on the use of two-component sensory systems to invoke phenotypes that increase virulence and recently one such system, the Salmonella PhoPQ system, has been demonstrated to respond directly to host defense peptides. ... 

Although the pundits will claim that the Golden Age of Antibiotics is long past, the necessity for new agents to combat infectious disease of all types is still with us, and with the massive misuse of potent antibiotics, the microbes that are now major causes of diseases of man (and animals) are rapidly exhibiting multiresistant phenotypes. Perhaps nowhere is the effect of multiple resistance phenotype seen more than in the problems that arise in the treatment of tuberculosis. Most if not all clinical strains are resistant to at least two if not more of the conunonly used antibiotics, and currently, increasing numbers of patients present with strains... 

In recent years, new resistance phenotypes (macrolide and streptogramin B antibiotics [MS] or partial macrolide and streptogramin B antibiotics [PMS], and macrolide antibiotics [M]) have been observed in elinical isolates of staphylococci and streptococci. Ross et al. [61, 125, 193] and Goldman and Capobianco [126] reported that MS-resistant strains of Staphylococcus epidermidis were resistant to 14- or 15-membered-ring macrolides and streptogramin B, but were susceptible to 16-membered-ring macrolide and lincosamide antibiotics. 

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