Almost 60 years ago the first antibiotics were developed, and they were created at a time when previously untreatable infections such as tuberculosis, gonorrhea, and syphilis could be almost miraculously cured. Infections like these could be a death sentence, and until recently they many be just that again. Microbes are learning the ability to fight of these antibiotics and become resistant to them. They are gaining resistance through a number of different ways, and science is in a race to keep up with there amazing evolution.
Bacteria are the common name for prokaryotic cells, which lack a nucleus. Rather they have a nucleoid region where their DNA is stored in direct contact with their cytoplasm. Their DNA, through transcription and translation, directs ribosomes to assemble proteins. They reproduce by binary fission, and are mostly heterotrophic. Bacteria can exchange DNA in three ways: transformation, transduction, and conjugation. In transformation a bacterial cell becomes competent, or able to take up DNA from the surrounding fluids. In conjugation two bacterial cells, a donor and a recipient join and DNA is transferred from one to the other. In these cases the new DNA either incorporates itself into the existing DNA or forms an independent molecule within the cell called a plasmid (Christensen).
Antibiotics are substances produced by microorganisms that kill or inhibit other microorganisms from growing or reproducing. Antibiotics are products of the earth and are all-natural. For clinical purposes, bacteria are said to be resistant to an antimicrobial when they are insignificantly affected by concentrations of the drug that can be achieved at the site of the infection. As might be expected, achievable concentrations vary dramatically from place to place in the body. Sensitivity of organisms to antimicrobials may be quantified by the minimum concentration required to inhibit their growth (minimum inhibitory concentration, MIC) or by the minimum concentration required to kill them within a specified period of time (minimum bactericidal concentration, MBC).
The Essay on Effect of temperature and SDS concentration on cell membranes of beet root cell
Five test tubes were labelled with the appropriate SDS concentrations to be tested. 6ml of 0, 0. 025, 0. 05, 0. 25, and 0. 5 %SDS concentration were added to each appropriately labelled tube. A beet cylinder was then placed in each tube for 20 minutes and gently shaken occasionally. The rest of the procedure was performed as outlined in the laboratory manual (Danyk, 2013/14) Data collection and ...
Because they are easier to measure and apply to both bactericidal and bacteriostatic drugs, MICs are more frequently used. Tables of typical MICs for many bacterial species/antimicrobial pairs are widely available. When combined with knowledge of the time course of antimicrobial concentrations at various sites in the body, these MICs can be used to guide rational selection antimicrobials for particular infections. Application of this rational approach to selection is still developing and unexpected results do occur. Microbial resistance to antibiotics can be inherent or natural resistance. Bacteria may be inherently resistant to an antibiotic. Other microbes developed acquired resistance. This is when bacteria can develop resistance to antibiotics. So bacterial population?s previously sensitive to antibiotics become resistant. This type of resistance results from changes in the bacterial genome (Stapleton).
Two genetic processes in bacteria drive acquired resistance: mutation and selection (or vertical evolution), or exchange of genes between strains and species (or horizontal evolution) (Garrett 420).
Vertical evolution is essentiality Darwinian evolution, which is driven by natural selection. So a spontaneous mutation in the bacterial chromosome imparts resistance to a member of the bacterial population. In the presence of the antibiotics then, the wild type (non-mutated) are killed and the resistant mutant is allowed to grow and flourish (Garrett 421).
The Essay on Bacterial Resistance
Bacterial resistance is a problem that has profoundly impacted the medical community. Bacterial resistance results when bacteria become resistant to individual antibiotics through the development of specific defense mechanisms which render the antibiotic ineffective. This problem has become evident in recent years as numerous cases have been reported in which antibiotics are not effective against ...
The mutation rate for most bacterial genes is approximately 10-8. This means that if a bacterial population doubles from 108 cells to 2 x 108 cells, and there is likely to be a mutant present for any given gene. Since bacteria grow to reach population densities far in excess of 109 cells, such a mutant could develop from a single generation during 15 minutes of growth resistance to other strains and species during genetic exchange processes (Levy).
The combined effects of fast growth rates, high concentrations of cells, genetic processes of mutation and selection, and the ability to exchange genes, account for the extraordinary rates of adaptation and evolution that can be observed in the bacteria. For these reasons bacterial adaptation, or resistance, to the antibiotic environment seems to take place very rapidly in evolutionary time (Stapleton).
Fleming first discovered penicillin, the first and most famous antibiotic, in 1929 when he found that a Penicillium mold inhibited the growth of bacteria in a petri dish. However, he failed to recognize the therapeutic potential of this and it remained for Florey, an Englishman, to first use Penicillin for therapy in 1940. It was, and is, one of the most active and safe antibacterials available. Because of their effectiveness and large therapeutic index, penicillin and many closely related derivatives, collectively known as the Penicillins, and the closely related Cephalosporines (discovered in the 1960s) are among the most important families of antibacterials available today. Penicillium and Streptomyces are major sources of antibiotics used therapeutically. Bacillus are the most notable bacterial group from which useful antibiotics have been derived. Synthetic antimicrobials, e.g., the sulfonamides, have always constituted an important source of antimicrobials. Semisynthetic antimicrobials are those derived from chemical modifications of naturally occurring antibiotics. This constitutes an ever more important group of antimicrobials as new drugs, with special properties, are developed.
The fundamental and most frequent grouping of antimicrobials is based on their chemical structure. Each of the following groups has a structural component that defines the group. Addition or subtraction of chemical groups from the core structure leads to the various members of the group. Some key groups are: a. Penicillins: derivatives of 6-aminopenicillanic acid. e.g., penicillin G b. Cephalosporins: derivatives of 7-aminocephalosporanic acid, e.g., cephalexin 2. Macrolides: have a large ring structure. Sometimes referred to as the “erythromycins.” e.g., 3. Lincosamides: name derived from the first member found, e.g., lincomycin 4. Aminoglycosides: composed of aminosugars linked by glycosidic bonds to various bases. e.g., gentamicin 5. Tetracyclines: have a rigid structure composed of 4 fused benzene-like rings. e.g., tetracycline. 6. Polypeptides: as the name says, aminoacids linked by peptide bonds form a major component of the structure. e.g., vancomycin, 7. Sulfonamides: derived from sulfanilamide, the first successful antibacterial, e.g., sulfadiazine. Trimethoprim is used to “potentiate” the sulfonamides. 8. Fluoroquinolones: e.g., enrofloxacin (BAYTRIL) 9. Miscellaneous: includes many drugs, such as chloramphenicol, nitrofurantoin, and isoniazid that have only one or two representatives of the class and are seldom referred to by their chemical nature in clinical practice. Antituberculosis and antileprosy drugs belong to one or more of the classes listed here, including miscellaneous. To keep up with evolving bacteria, scientists are attacking efflux pumps. Efflux pumps are what microbes use to rid themselves of toxic materials and drugs. The way science is perusing this is to attach these pumps with compounds called efflux-pump inhibitors. These compounds have no infection fighting power but can make current antimicrobial drugs more effective (Christensen).
The Term Paper on Side Effects Antibiotics Bacteria Antibiotic
Antibiotics have played a major role in our society thanks to Sir Alexander Fleming's careful observations in 1928. Without it, many lives would be in danger due to infectious diseases. Antibiotics are chemical substances produced by various species of microorganisms and other living systems that are capable in small concentrations of inhibiting the growth of or killing bacteria and other ...
Microbes that caused sickness in the preantibiotic era are again making people sick because some of these microbes have become resistant to antibiotics. Various bacterium are now resistant to one or more classes of antibiotics; penicillins, cephalosporins, tetracyclines, quinolones, aminoglycosides, and macrolides. These Bacteria can resist the drugs in several ways. They can alter it so that it’s no longer toxic. Or they can modify their own components so that the antimicrobial compound can’t bind to them nor have an effect on them (Garrett 432).
Recently microbiologists have found that bacteria can also expel drugs, thus lowering the internal concentration enough that the microbes escape the treatment’s intended effects (Christensen). Most efflux pumps probably evolved to handle toxins in the environment and only by luck pump out antibiotics, and it is still unknown how these pumps work. Each pump is made up of one or several proteins that span the cell membrane of the microbe. Two theories on how efflux pumps actively expel a drug is through a local channel or by propelling the drug across the cell membrane. Efflux pumps are known to be responsible for a moderate level of resistance in many different species of bacteria and against several drugs. Not all microbes have efflux pumps, and the ones that do employ widely varying numbers and types. Some microbes always have abundant pumps, and others manufacture additional pumps after exposure to drugs (Christensen).
The Term Paper on The Evolution Of Antibiotic Resistant Bacteria
Since antibiotics, such as penicillin, became widely available in the 1940 s, they have been called miracle drugs. They have been able to eliminate bacteria without significantly harming the other cells of the host. Now with each passing year, bacteria that are immune to antibiotics have become more and more common. This turn of events presents us with an alarming problem. Strains of bacteria that ...
Efflux pumps help explain why some bacteria are less susceptible to drugs than others are. Some species of bacteria seem to use efflux pumps to resist tetracyclines, macrolides, and fluoroquinolones well enough to often make these antibiotics useless weapons. ?Since efflux pumps can act on more than just one kind of antimicrobial agent, microbes may develop resistance against several different drugs simultaneously?(Tulkens in Christen).
Between 40 and 90 percent of some bacterial pathogens carry efflux pumps for most of the major classes of available antibiotics (Christensen).
With the information now known, efflux pumps opens up opportunities for pharmaceutical companies to find compounds that will disrupt this microbial activity. As drugs, efflux-pump inhibitors aren’t expected to have a significant antimicrobial effect on their own and companies are now developing these compounds. They are expected to reverse acquired drug resistance in microbes that are susceptible to antibacterial and antifungal drugs. Also efflux-pump inhibitors might make some microbes that are intrinsically drug resistant vulnerable to antibiotics, and those efflux-pump inhibitors will reduce the chance that bacteria will successfully reproduce enough times to select for a drug-resistance mutation (Christensen).
The Essay on Antibiotic Resistance Resistant Bacteria
Antibiotic resistance in bacteria: "The more times you use a drug, the more it will decrease the effect it has on you." For about 50 years, antibiotics have been the answer to many bacterial infections. Antibiotics are chemical substances that are secreted by living things. Doctors prescribed these medicines to cure many diseases. During World War II, they treated one of the biggest killers during ...
Efflux pumps are not the only problem, many bacteria were capable of using sporulation to their advantage in the face of’ antibiotics and other threats. Like plant seeds, they would go dormant, toughen their cell walls to a nearly impermeable state, and wait. When conditions were favorable, the bacteria would reactivate, their cell walls once again becoming permeable. Some forms of resistance involved the bacteria’s use of genes that triggered sporulation when the microbes were threatened, or created an even less vulnerable cell wall at the time of sporulation (Garrett 428).
Under such conditions, microbes could drift about unharmed in solutions designed specifically to kill them. Sporulation mutants can withstand all disinfectants, such as chlorine- and ammonia-based cleansers, soaps, extremely salty or acid solutions, and even high heat. An example of this would be a number of organisms, including strains of cholera, E. colt, and the Legionnaires’ disease bacteria, had developed some resistance, through such sporulation mechanisms, and other means, to chlorine. They are partially tolerant, not all together resistant, because the microbes were able to survive in doses of chlorine that usually killed their species. To ensure safe drinking water in the presence of such bugs, higher doses of chlorine were needed (Garnett 428) At drug and biotech companies across the United States, scientists have set their sights on a most elusive target: drug-resistant microbes. Working in pharmaceutical- biotechnology partnerships, researchers are trying every trick in the book-including high-tech drug discovery, genome sequencing, and development of new vaccines-to overcome resistant pathogens. Successful companies stand to gain a significant share of the $23 billion antibiotics market(Brown).
A handful of new or improved antibiotics geared to resistant bugs are in various stages of clinical trials, and ideas for novel therapeutics abound. Like, resistance-related genes may lie within human and bacterial genomes currently being sequenced in various large-scale projects. According to a newly released World Health Organization (WHO) annual report, drug-resistant strains of microbes have evaded common treatments for tuberculosis (TB), malaria, cholera, and pneumonia. The widespread use of antibiotics contributes to drug resistance. The longer bacteria are exposed to a drug, the more likely they are to evolve a way around it. Today, 160 antibiotics, all based on a few basic chemical structures, are on the market. Researchers suggest these drugs may be overprescribed. Patients often fail to complete antibiotic therapy; they stop taking drugs as soon as they feel better. Bacteria still in the body can rebound, developing resistance to the drug at hand in the host’s system. Such misuse of prescriptions, combined with societal conditions-such as the growth of day-care centers and increased long-term care in hospitals-provides an environment where drug-resistant microbes can emerge and thrive (Brown).
The Essay on The Problems With Antibiotic-Resistant Bacteria
Abstract The aim is to summarize, evaluate and argue the validity of information that demonstrates the issues with antibiotic-resistant bacteria. A plan to minimize/reduce these issues in the future shall be presented with explanations regarding effectiveness. The Problems with Antibiotic-Resistant Bacteria Antibiotic-Resistance is the ability of bacteria and other microorganisms to resist the ...
Science, is many fields, is working on a varying answer for this problem. But they must work fast to counteract the problem, because is the microbes become resistant to are antibiotics, where does that leave us? Extinct (Magee)!
Bibliography:
Brown, Kathryn. The Scientist, Vol:10, #12, p.1, 8-9 , June 10, 1996. Christensen, Damaris. ?Keeping Bugs from Pumping Drugs.? Science News 157 no7 F 12 2000. Garrett, Laurie. The Coming Plague. New York: Farrar, 1994. Levy, Stuart B. Antimicrobial resistance. British Medical Journal, Sept 5, 1998 v317 p612. Magee, J T. ?Antibiotic Prescribing and Antibiotic Resistance in Community Practices.? British Medical Journal, Nov 6, 1999 v319 i7219 p1239. Stapleton, Stephanie. ?Counterattack (Antibiotics and Bacteria).? American Medical News, June 1, 1998 v41 n21 p31(1).
