Bacteria and Antibiotic Resistance Essay Example | Topics and Well Written Essays - 1500 words

Bacteria and Antibiotic Resistance - Essay ExampleVirulence and pathogenicity refer to the ability of bacteria to cause disease. Bacteria atomic number 18 complex (while viruses must(prenominal) live in a horde (us), bacteria can live independently) and so are easier to kill (Antibiotics, Bacteria and ( ordinarily not) Viruses 2007). The traditional criteria for establishing that a bacterium is prudent for a disease hasten been Kochs postulates, which were developed in 1882. Although serving well for many years, these postulates have limitations (1) not all bacteria can be cultured, (2) not all members of a species are equally virulent, and (3) adequate animal master of ceremoniess are not always available. Host susceptibility is an important virulence factor for bacteria. The freshman important step in bacterial pathogenesis is adherence to a host cell. This occurs by means of pili, which consist of long rods that extend out from the bacterial surface. The tips of the pili stop over proteins that attach to host cell receptors. In some cases, pilin, the protein subunits of the pilus shaft, attach to the host cells receptors. In addition to pili, bacterial surface proteins called adhesins attach firmly to the host cells (Walsh 2003, p. 34). Sometimes the host makes antibodies against pili or adhesin proteins, and this induces the bacteria to make different types of adhesins. Only Gramnegative bacteria make adhesins the mechanism of how Gram-positive bacteria attach to a host cell is not known (Walsh 2003).The virulence of many bacterial pathogens is due to the toxins they produce, which disrupt normal cell functions and cause cell death. Scholar and Pratt (2000) explain that exotoxins are proteins that are excreted by dividing bacteria. Exotoxins that attack a variety of cell types are called cytotoxins (p. 76) those that attack a particular cell type or tissue have specific names, such as neurotoxin, leukotoxin, hepatotoxin, or cardiotoxin. Exotoxins c an be associated with a specific bacterial disease. In addition to toxic proteins, pathogenic bacteria as well produce hydrolytic enzymes that degrade host tissues and disseminate bacteria within the host. Heat-shock proteins produced by bacteria stimulate autoimmune responses so that host antibodies and T-cells attack healthy host cells (Scholar and Pratt 2000). The essential property that differentiates antibiotics from antiseptics is that they are sufficiently selective to allow their use within the body, rather than just on the surface. This selective toxicity is not imperious but it is quantifiable as we shall see in chapter 6. There is, therefore, always room for improvements and developing drug licensing regulations seek improvements in the comparative safety of antibiotics. Antibiotics wee-wee by destroying either the proteins that build a bacteriums cell wall or the protein-producing ribosomes (Greene 2000, p. 23). The drug must inhibit the target bacteria at lower conce ntrations, usually much lower, than those concentrations that produce toxic effects in humans. Some antibiotics can be given in very high doses without toxic effects, e.g. penicillins, but others whitethorn produce serious toxicity at levels that are not much above those required for treatment of infection. Many alterations to antibiotics have been made to improve this selectivity though with some antibiotics this is virtually impossible to achieve. The most selective antibiotics tend to be those that inhibit a process in bacteria that does