The Use Of Ampicillin And Oxacillin Biology Essay


The word antibiotic comes from the Greek anti and bios . An antibiotic is a drug that kills or slows the growth of bacteria. Antibiotics are one class of antimicrobials, a larger group which also includes anti-viral, anti-fungal, and anti-parasitic drugs. Antibiotics are chemicals produced by or derived from microorganisms (i.e. bugs or germs such as bacteria and fungi). They were first discovered in 1928 and are among the most frequently prescribed medications in modern medicine.

Antibiotics are used to treat many different bacterial infections. They cure disease by killing or injuring bacteria. Bacteria are simple one-celled organisms that can be found, by the billions, all around us: on furniture and counter-tops, in the soil, and on plants and animals. They are natural and some are needed as part of human life. These are called normal flora and are always present in the body.

The normal flora is not harmful to the body unless when the body's physical barrier is broken. In such cases they are able to infect many vulnerable parts of the body including the eyes, ears, throat, sinuses, lungs, airways, skin, stomach, colon, bones, and genitals. To be able to treat such situations the bacteria of the normal flora have to be studied and in order to know which antibiotic it is resistant to and which it is not resistant to.

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Each different type of antibiotic affects different bacteria in different ways. For example some are 'bactericidal', meaning that they work by killing bacteria. Other antibiotics are 'bacteriostatic', meaning that they work by stopping bacteria multiplying. A proper example is an antibiotic which inhibit a bacterium's ability to turn glucose into energy, or its ability to construct its cell wall. Thus killing the bacterium instead of allowing reproduction. Some others antibiotics can be used to treat a wide range of infections known as 'broad-spectrum' antibiotics. Others are only effective against a few types of bacteria and are called 'narrow-spectrum' antibiotics.[1][2]


Ampicillin is closely related to amoxicillin, another type of penicillin, and both are used to treat urinary tract infections, otitis media, Hamophilus influenza, salmonellosis and Listeria meningitis. It is used with flucloxacillin in the combination antibiotic co-fluampicil for empiric treatment of cellulitis; providing cover against Group A streptococcal infection whilst the flucloxacillin acts against the Staphylococcus aureus bacterium. Of concern is the number of bacteria that become resistant to ampicillin necessitating combination therapy or use of other antibiotics.

All Pseudomonas and most strains of Klebsiella and Aerobacter are considered resistant.

An ampicillin resistance gene is commonly used as a selectable marker in routine biotechnology. Due to concerns over horizontal gene transfer to pathogenic organisms in the wild, the European Food Safety Authority restricts use of this gene (among other resistance genes) in commercial genetically modified organisms. The enzyme responsible for degrading ampicillin is called beta-lactamase, in reference to the beta-lactam structure of ampicillin and related drugs.[3] [4]


Oxacillin sodium (trade name Bactocill) is a narrow spectrum beta-lactam antibiotic of the penicillin class. It was developed by Beecham. Oxacillin is a penicillinase-resistant β-lactam. It is similar to methicillin, and has replaced methicillin in clinical use. Another related compound is nafcillin. Since it is resistant to penicillinase enzymes, such as that produced by Staphylococcus aureus, it is widely used clinically in the US to treat penicillin-resistant Staphylococcus aureus. However, resistant strains called oxacillin-resistant Staphylococcus aureus (MRSA/ORSA) are highly prevalent in the U.S. and the U.K.[5]


Erythromycin is found in a group of drugs known as macrolide antibiotics, which are responsible to reduce the growth or sometimes kill sensitive bacteria. This is done by the reduction in production of certain important proteins required for bacterial survival. Erythromycin is used to treat many different types of infections caused by bacteria such as:  streptococcal infections of the throat and skin and lung infection by streptococcal pneumonia. This antibiotic should not be taken in cases of allergies and conditions like; liver disease, myasthenia gravis and heart rhythm disorder.[6]


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Levofloxacin inhibits bacterial type II topoisomerases, topoisomerase IV and DNA gyrase. Levofloxacin, like other fluoroquinolones, inhibits the A subunits of DNA gyrase, two subunits encoded by the gyrA gene. This results in strand breakage on a bacterial chromosome, supercoiling, and resealing; DNA replication and transcription is inhibited.[7]

With this information in mind it gives reason for carrying out the project. Such that after the normal flora in the throat of subjects is identified, their antimicrobial susceptibility can be tested. Then if the body's physical barrier were broken and they their normal flora had to become paracitic, the situation can be treated as soon as possible.


Gram staining is a quick procedure used to look for the presence of bacteria in tissue samples and to characterise bacteria as Gram-positive or Gram-negative, based on the chemical and physical properties of their cell walls. The microorganisms have a relatively thin cell wall consisting of a few layers of peptidoglycan surrounded by a second lipid membrane containing lipopolysaccharides and lipoproteins. These bacteria do not retain crystal violet dye in the Gram staining protocol due to their lipopolysaccharide outer layer. In a Gram stain test, a counterstain (commonly safranin) is added after the crystal violet, coloring all Gram-negative bacteria with a red or pink color.

As from result table it has been has been noticed levofloxacin and oxacillin are found to be the most effective antimicrobials. Also the individuals living in the residence are found to experience a greater resistance to antimicrobials as they found in a confound environment. This basically implies these individuals share a lot of materials together, thus microbes. This increases chances of microbe resistance through exchange of plasmids.


This experiment has enable the better understanding of antibiotic resistance and as such helped in the understanding of new things with respect to carrying out similar experiments , such that in future it colud be carried out in a better way to make results better.

Some recommendations are:

The tongue and teeth should avoid being touch with the sterile swabs when collecting bacteria samples to improve results.

Do API (used for the identification of members of the family enterobacteriaceae and other gram-negative bacteria) on bacteria for better identification.

Get more details during observations such as to help when writing up reports.

Aseptic techniques should be taken much more seriously.

Respect incubation periods more strictly. Too much incubating may cause bacteria to sink into the agar.

Antibiotics are extremely important in medicine, as they are used to treat many different bacterial infections but unfortunately bacteria are capable of developing resistance to them. Resistance to antibiotics poses a serious and growing problem, because some infectious diseases are becoming more difficult to treat. Resistant bacteria do not respond to the antibiotics and continue to cause infection.