A Study On Microbes And Antibiotics Biology Essay


An antibiotic is simply a substance that is synthesized by a microbe and released with intention to kill or harm another microbe. With this being said, there are a number of different ways in which an antibiotic from a microbe can harm another microbe. Antibiotics can either kill microbes directly (bactericidal) or they can inhibit the growth of microbes (bacteriostatic) ( Case C, Funke B, Tortora G 2010).

In 1928, Alexander Fleming, a Scottish bacteriologist, accidentally discovered the first antibiotic when he noticed that growth of contaminant Penicillin notatum mold colonies on his culture plates were inhibiting the growth of Staphylococcus bacteria. Fleming gave the name "penicillin" to the inhibitory substance being produced by the mold. He found that broth cultures of the mold were non-toxic to laboratory animals and that they destroyed staphylococci and other bacteria. He speculated that penicillin might be effective in treating infectious diseases caused by these organisms (Burton, Engelkirk 2004)."

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During the World War 2, two biochemists, Sir Howard Walter Florey and Ernst Boris Chain, purified penicillin and demonstrated its effectiveness in the treatment of various bacterial infections. By 1942, the United States of America drug industry was able to produce sufficient penicillin for human use, and the search for other antibiotics began (Burton, Engelkirk 2004).

There are many different types of antibiotics available. With this being said, it may still be a perplexing phenomenon why people still develop resistance whilst there are hundreds of types that they could utilize. Truth is that these antibiotics are generally illness specific, just as one cannot use a topical antibiotic to treat a respiratory infection and the other reason is because resistance to one type of antibiotic may also induce resistance to another type of antibiotic (National Health Services 2010). The antibiotics that are being tested in this experiment are discussed below.

Penicillin is effective against most gram positive microbes i.e. streptococcus and staphylococcus and also some gram negative microbes, it is rendered to be effective to a wide variety of organisms it is widely used and consequently people develop resistance to this antibiotic the most (National Health Services 2010).

Ampicillin falls within the penicillin group of antibiotics. Such is used to treat illnesses such as pneumonia, bronchritis, lung infection, gonorrhea, ear infection and urinary tract infections (Case C, Funke B, Tortora G 2010).

Erythromycin can be altinated for people that have allergy reaction to penicillin or those that are resistant to a strain of penicillin (National Health Services 2010).

Oxacillin has a narrow range of target microbes. It specifically targets microbes that produce beta lactamase enzyme. Such bacteria are known to be resistant to natural penicillin (National Health Services 2010). Like ampicillin, oxacillin falls within the penicillin group of antibiotics (Case C, Funke B, Tortora G 2010).

Erythromycin is the most frequently used marcrolide antibiotic and is synthesized by Streptomyces erythraeus. Erythromycin is a relatively broad-specrum bacteriostatic antibiotic effective against gram-positive bacteria, mycoplasmas and a few gram-negative bacteria (Harley, Klein, Prescott 1993).

Erythromycin is used for patients that are resistant to penicillin and also to treat diseases such as bronchitis; diphtheria; Legionnaires' disease; pertussis (whooping cough); pneumonia; rheumatic fever; venereal disease (VD); and ear, intestine, lung, urinary tract, and skin infections. It is also used before some surgery or dental work to prevent infection. Antibiotics will not work for colds, flu, or other viral infections (American Society of Health-System Pharamcies 2010).

Levofloxacin is active against most aerobic gram-negative and gram-positive organisms and demonstrates moderate activity against anaerobes (Chen , Ho, Lay , Tsai , Wang , Wang 2009).

The genes for drug resistance are present on both the bacterial chromosome and plasmids. Frequently, a bacterial pathogen is drug resistant because it has a plasmid bearing one or more resistance genes; such plasmids are called R plasmids (resistance plasmids) (Harley, Klein, Prescott 1993).

Some bacteria are naturally resistant to a particular antimicrobial agent because they lack the specific target site for the drug (e.g. mycoplasmas have no cell walls and are, therefore resistant to any drug that interfere with cell wall synthesis). Other bacteria are naturally resistant because the drug is unable to cross the organsim's cell wall or cell membrane and thus, cannot reach its site of action (e.g. ribosomes). Such resistant is known as intrinsic resistance (Burton, Engelkirk 2004).

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It is also possible for bacteria that were once susceptible to a particular drug to become resistant to it; this is called acquired resistance (Burton, Engelkirk 2004).

Bacterial usually become resistant to antibiotics and other antimicrobial agents by one of the 5 modes of bacterial action (Burton, Engelkirk 2004).

Inhibition of cell wall synthesis

Inhibition of nucleic Acid Synthesis

Injury to the plasma membrane

Inhibition of protein synthesis

Inhibition of synthesis of essential metabolites

In recent years, microbes have developed resistance at such a rapid pace that many people, including many scientists, are beginning to fear that science is losing the war against pathogens. Some strains of pathogens have arisen that are resistant to all known drugs; examples include certain strains of Mycobacterium tuberculosis (the causative agent of tuberculosis), Plasmodium spp. (the protozoan causative agent for malaria), and Staphylococcus aureus (he bacterium that causes many different types of infections, including pneumonia and post-surgical wound infections). To win the war against drug resistancem more prudent use of currently available drugs, the discovery of new drugs, and the development of new vaccines will all be necessary (Burton, Engelkirk 2004).

The aim of this experiment is to evaluate and compare antimicrobial drug susceptibilities of the throat bacterial organisms among students of Midrand Graduate Institute wherby group 1 were students that stay off-campus and group 2 comprised of students that stay on-campus. This is all done to see which group is more resistant to antibiotics.