Antibacterial agents resistance

Antibacterial Agents. There is a continuous need for new antibiotics primarily as a result of bacterial resistance. There are two aspects to this phenomenon. Fkst, as the mote common pathogens are contioUed by antibiotics, less common, highly resistant organisms present mote prominent health... 

Antimicrobial Activity. The elfamycins antimicrobial specificity and lack of toxicity in animals can be explained in view of species-dependent specificity of elfamycin binding to EE-Tu. Inefficient cellular uptake or the presence of a nonresponding EE-Tu were cited as responsible factors for the natural resistance in Halohacterium cutiruhrum (67), Lactobaci//us brevis (68), and in actinomycetes (5,69). The low activity of elfamycins against S. aureus was also attributed to an elfamycin-resistant EE-Tu system (70). However, cross-resistance with other antibacterial agents has not been observed (71). 

Although the antibacterial spectmm is similar for many of the sulfas, chemical modifications of the parent molecule have produced compounds with a variety of absorption, metaboHsm, tissue distribution, and excretion characteristics. Administration is typically oral or by injection. When absorbed, they tend to distribute widely in the body, be metabolized by the Hver, and excreted in the urine. Toxic reactions or untoward side effects have been characterized as blood dyscrasias crystal deposition in the kidneys, especially with insufficient urinary output and allergic sensitization. Selection of organisms resistant to the sulfonamides has been observed, but has not been correlated with cross-resistance to other antibiotic families (see Antibacterial AGENTS, synthetic-sulfonamides). 

The second general mechanism to cause resistance to antibacterial agents is to prevent the drug from reaching its target site. This is either achieved by altered rates of entry (reduced uptake) or by the active removal of the dtug (active efflux) [4]. 

Pseudomonas aeruginosa is resistant to many antibacterial agents (Chapters 9,13) and is biochemically very versatile, being able to use many disinfectants as food sources. 

Stickler D.J. King J.B. (1998) Intrinsic resistance to non-antibiotic antibacterial agents. In Principles and Practice of Disinfection, Preservation and Sterilisation (eds A.D. Russell, W.B. Hugo G. A J. Ayliffe), 3rd edn. Oxford Blackwell Science. 

Adverse effects are generally mild and include dryness, erythema, and itching.18 Although rare and seen most often with oral therapy, pseudomembranous colitis can occur with the use of topical clindamycin.19 As with any antibacterial agent, the possibility of resistance exists with the use of topical erythromycin. However, co-administration of erythromycin and benzoyl peroxide has been shown to decrease the incidence of resistance, as well as to improve symptoms of mild to moderate inflammatory acne.20... 

Table 1 Examples of action and resistance mechanisms found in bacteria for different classes of antibacterial agents ...

For livestock producers to approach the care we have exercised in in avoiding antibiotic exposure would require a complete ban of all antibiotics and other antibacterial agents. Periodic exposure to prophylactic or therapeutic levels of antibacterials would result in high levels of resistance and, in a production environment, that resistance would be very slow in declining. 

In its report ( 3) issued in 1972, the Task Force acknowledged the potential human and animal health hazard of drug resistant bacteria and made a number of recommendations. In addition to basic research to better understand the nature of the problem, the Task Force recommended that restrictions be placed on the use of antibacterial agents in feeds which fail to meet guidelines established by the Task Force in regard to safety and/or efficacy. Agents that do not meet these standards would be prohibited from growth promotion and any subtherapeutic use in animals but could continue to be used at therapeutic levels for short-term treatment on the order of licensed veterinarians. 

Aminoglycoside resistance has been a powerful impediment to the continued use of these potent antibacterial agents. The myriad of strategies that confer resistance... 

There are four general properties for a good antibacterial agent. It must be selective. Eliminating all species of bacteria from the body may leave the patient prone to superinfection. It should kill bacteria rather than just prevent their multiplication it should be bactericidal rather than bacteriostatic. Bacteria should not develop resistance to the drug. Lastly,... 

The problem of antibiotic-resistant bacteria has created a pressing demand for new antibacterial agents with novel mechanisms of action. Af-Formylhydroxylamines, also known as reverse- or retro-hydroxamates, are one of the few novel targets that are currently being pursued against a variety of metalloenzyme targets, including carboxy... 

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