Lab Experiment: The Effectiveness of Different Antibiotics on Bacteria

To develop problem solving and experimental skills, for example, information is accurately processed and presented, experimental procedures are planned, designed and evaluated properly, producing valid results, recording results, and valid conclusion is drawn.

Escherichia coli are rod shaped, gram negative bacteria often found in the gut of humans and other warm-blooded mammals (Jacques & Ngo, 2004). It is transmitted primarily through faecal contaminated food and water. Most strains of E. coli are not harmful to humans, however some strains are pathogenic and can cause symptoms including diarrhoea (Unknown, 2012).

AIM – The aim of the experiment is to determine the relative effectiveness of several anti-microbial substances on developing pathogens. (E. coli)

The antibiotics will have different zones of inhibition on different bacteria. Also, a range of concentrations of the nutrients in the bacteria will change the bacterial growth.

use of E.Coli (Escherichia coli), a common bacteria found in the intestines of warm-blooded or-

The aim of this investigation was to find out which antiseptics were most effective at preventing the growth of bacteria.

The natural habitat of Escherichia Coli is in the gastrointestinal tract of mammals and humans. It is the most abundant of the bacteria found there. The benefits of having Escherichia Coli living in the intestines are it helps digest your food and even produces vitamins K and B12. It can also be found outside the body in fecal-contaminated water or mud. If this

Escherichia coli, oe e.coli, is a safe bacteria found in the large intestine, but also a dangerous bacteria outside of the body. While inside the body the bacteria produces vitamin K which cannot be obtained from food. Therefore e.coli is an essential bacteria in the human body. This bacteria is also a facultative anaerobe meaning it can live with and without oxygen. This means that it can thrive inside of the body, but it can also thrive outside of the body. When e.coli is outside of the body it is very dangerous. E.coli can be found in uncooked meats, unpeeled vegetables, unwashed fruits, and everything contaminated with feces. Dr. Harrlet Burge (2011) stated that e.coli can survive in water for up to 100 days and can remain in soil for as many as 15 weeks. Once the e.coli bacteria infects a human being, the person will experience diarrhea and abdominal pain, both from the bacteria

Bacitracin (B-10) was measured at 0mm in diameters. There was no susceptibility. Therefore, with the zone size as 0, Escherichia coli was resistant to bacitracin

George’s University Bay, and to quantify the bacterial colonies using various experimental methods. Drinking or eating seafood from bacterially contaminated water sources has lead to pathogenic infection due to Escherichia coli (Das et al., 2013). Escherichia coli has been used in multiple studies to research aspects of water quality and bacterial affects on specific target hosts. Escherichia coli is mostly known for causing diarrhea symptoms and gastrointestinal difficulties (Kenny et al., 1997). Enteropathogenic strains of Escherichia coli are known to cause serious cases of diarrhea, such as, cholera and shigella (Kenny et al., 1997). Many sea organisms can become in contact with pathogenic microbes due to the amount of contaminated matter present in the water (Potasman et al., 2002). This can lead to the ingestion of E.coli bacteria and the hospitalization of victims who consumed the seafood (Potasman et al.,

Three of the four quadrants were labeled S, P, T, for streptomycin, penicillin, and tetracycline. One quadrant was left blank for the control (Figure 1.1) Having a control of no antibiotic was used to show the growth of the bacteria when it is uninhibited by antibiotics. Then, Escherichia coli K12 from VWR (catalog #470179-082) and Staphylococcus aureus from VWR (catalog #470179-208) were evenly swabbed across the surface of the agar plate with a cotton swab; ten plates, contained E. coli and the other ten plates contained S. aureus. Then, Streptomycin (10 μg/mL), Penicillin (10 U = ~10 μg/mL), and Tetracycline (30 μg/mL) were obtained and placed into the middle of their respective quadrants. After this, the agar plates were stacked into two stacks of five, for each bacteria, were wrapped with parafilm, and were incubated at 37°C for 48 hours (Figure 1.2). After 48 hours, the plates were moved to a refrigerator at 4°C, until they were taken out of the fridge approximately a week after the stacks of agar plates had initially been placed in the incubator. The diameters of the zones of inhibition were then measured with a ruler and recorded to the nearest millimeter. After measuring the zones of inhibition, a gram-staining technique was used to illustrate the difference in cell wall structure between S. aureus and E. coli. First, a small sample of each species of bacteria was transferred with a loop from the agar plate onto two different areas on a microscope slide that had previously been washed, wiped with alcohol, and dried. Then a drop of water was added to each bacterial sample, was smeared into a thin layer, then allowed to air dry. Once the bacterial samples were dry, the slide was held at one end and was passed through a Bunsen burner flame with the smeared-bacteria samples facing up.

In order to control the growth and spread of harmful microbes that can cause disease, we use antimicrobial agent. Disinfectants are antimicrobial agents that are use in a physical process or used in a form of a chemical agent. Disinfectants are used to destroy vegetative pathogen but are not effective against bacterial endospores. Disinfectants remove harmful products of toxins from material and usually are used on inanimate objects since they can be harmful to human tissues. Another antimicrobial agent used is, antibiotics. Antibiotics are usually prescribed to a person to cure a bacterial or viral infection. Antibiotics are used to inhibit the growth of infectious agents in the human body. The disk diffusion test known as the Kirby-Bauer

The only disadvantage of using these kinds of drugs is that these drugs can be used if the cause of an infection is known; if the right narrow-spectrum drug is not chosen then there is a chance that the infection will persist because the

E. coli (also known as escherichia coli) is a bacteria that normally lives in the intestines of people and animals named after Dr. Theodor Escherich. Most E. coli are harmless and actually are vital to a healthy human intestinal tract. However, some E. coli are pathogenic, meaning they can cause either diarrhea or illness outside of the intestinal tract(cdc.gov). According to Food Safety.gov, you can get E. coli by eating contaminated food, especially undercooked ground beef,

E. coli usually resides in the intestines of humans and is beneficial to humans and animals. Most of the E. coli strains are not harmful, although some of the E. coli variants are pathogenic in nature and cause various intestinal problems (CDC, 2015). Meat usually contains bacteria,