Antibiotics Microbial growth is a normal essential part of the healthy human, animal, and plant environment. When introduction to a microorganism causes harmful bacterial growth, using antimicrobial therapy can eradicate or reduce the unwanted pathogen.
Prior to the development of effective modern antibacterials, serious systemic bacterial infections were as feared as is AIDS today. Now we are faced with the major problem of increasing bacterial resistance to antibacterial drugs.
Prior to the discoveries outlined below, bacterial infections were major causes of death. Even relatively insignificant wounds could become sources of "blood poisoning" leading to death.
Such infections are now viewed almost casually, except in patients with compromised body defenses. Ehrlich, who was active in the early 20th century, had access to many new compounds from the active German chemical industry. He studied the interactions of these chemicals with infectious protozoans and bacteria.
He found that some of the chemicals bound preferentially to some protozoans and were effective as therapeutic agents, but the margin of safety was extremely narrow. He found no chemicals active against bacteria at concentrations that were non-toxic in infected animals, but his general experimental approach and concepts were useful to others who followed.
Nonetheless, prontosil was safe enough to be used therapeutically and constituted the first clinically useful chemotherapeutic agent for bacterial infections.
Dramatic proof of the efficacy of this new agent was provided during an outbreak of meningococcal meningitis in the French Foreign Legion in Nigeria. Sulfanilamide and its relatives which soon followed were said to have "dethroned the captain of the men of death," such was their effectiveness in treating pneumonias.
However, he failed to recognize the therapeutic potential of this and it remained for Florey, an Englishman, to first use Penicillin for therapy in It was, and is, one of the most active and safe antibacterials available.
This was the first of many therapeutically active drugs found to occur naturally in various species of Streptomyces, fungi which are found in soils throughout the world. The aminoglycoside antibiotics are extremely important in clinical medicine, today.
Streptomycin was especially active against many gram negative bacteria which had been resistant to the action of penicillin. With Streptomycin for gram negative bacteria, penicillin for gram positive bacteria, and the sulfonamides for a broader spectrum, it was erroneously thought that bacterial diseases had been conquered for good.
In fact, penicillin and streptomycin were so effective when used together that they were combined into a single dose form. Such dose forms are now illegal in human medicine and are frowned on in veterinary medicine for reasons that will become apparent later. It was isolated from a Streptomyces organism.
In addition to a wide spectrum of gram positive and negative bacteria, chloramphenicol is active against such organisms as Rickettsia. Its acute toxicity was so low and efficacy so great that it was used heavily, to the point of abuse. In the mid s, it was discovered that chloramphenicol caused aplastic anemia and other blood dyscrasias in a small proportion of patients.
This discovery drastically reduced its use and it is now recommended only for those cases where it is truely needed and other antimicrobials are likely to be ineffective. Chloramphenicol did not lead to the development of a large family of drugs, although a few derivatives are now available or being tested.
Their spectrum includes many gram positive and negative bacteria as well as Rickettsia and some protozoans. The tetracyclines are very important in current therapy.
Definitions top main topics e-mail Some commonly used terms are defined below. One should pay particular attention to the distinction betweem antimicrobial and antibiotic! Cancer cells are also considered as living, foreign cells.
The latter refers to the use of drugs that alter the rate of natural, ongoing reactions and processes in the patient's body.
Antibiotics may have e.Antimicrobial Drug Sensitivity Testing Essays: Over , Antimicrobial Drug Sensitivity Testing Essays, Antimicrobial Drug Sensitivity Testing Term Papers, Antimicrobial Drug Sensitivity Testing Research Paper, Book Reports.
ESSAYS, term and research papers available for UNLIMITED access. Antibiotic Sensitivity lab A. Define the term selectively toxic.
Why is it an important feature of antimicrobial agents? Selective toxicity is the ability of a chemical or drug to . Microbial growth is a normal essential part of the healthy human, animal, and plant environment. When introduction to a microorganism causes harmful bacterial growth, using antimicrobial therapy can eradicate or reduce the unwanted pathogen.
Antimicrobial Drug Sensitivity Testing Introduction Antimicrobial sensitivity testing is important clinically because the proper selection of an antimicrobial drug in the treatment of a bacterial infection is ideally based on the knowledge of the sensitivities of the infecting organism.
Antimicrobial Sensitivity Testing Introduction Antimicrobial sensitivity testing is important clinically because the proper selection of an antimicrobial drug in the treatment of a bacterial infection is ideally based on the knowledge of the sensitivities of .
Antimicrobial sensitivity testing is important clinically because the proper selection of an antimicrobial drug in the treatment of a bacterial infection is ideally based on the knowledge of the sensitivities of the infecting organism.