Methods And Methods Of Antibiotic Sensitivity Testing

Gram-positive and gram-negative bacterium’s sensitivity to penicillin will be measured by the zone of inhibition. The zone of inhibition is an area on an agar plate between the antibiotic and the bacteria. The further the bacteria grows away from the antibiotic, the more sensitive it is to the antibiotic. The null hypothesis is that there will be no difference in sensitivity between gram-positive and gram-negative bacterium. The alternate hypothesis is that the gram-positive bacterium will be more sensitive to the penicillin antibiotic. Based on previous studies [7], it is predicted that gram-positive bacterium will be more sensitive to the antibiotic because of its exposed peptidoglycan layer, while the gram-negative bacterium will be less sensitive due to its outer membrane not being in direct contact with the outside

Antibiotics are powerful very frequently used potential drugs in fighting bacterial infections worldwide, [1]. These agents saved millions of lives in the past fifty years in both hospital-based and outpatient settings. Inadequate measures to control the spreading of infections, overprescribing as well as inappropriate selection and dosing of antibiotics by healthcare providers, unfettered access to antimicrobials by public, failure to adhere to clinically desired treatment regimens are some of the driving force to spread of antibiotics resistance, [2]. In addition, lack of regulations to promote the rational use of antibiotics in humans, infection prevention and control are some of the other factors that lead to emergence of resistance to antibiotics, [3].

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.

E.coli outbreaks have steadily grown over the last few decades. An expansion in big farming has led to E. coli not only being found in meat, but vegetation as well, due to waste runoff. This has increased our need for adequate antibiotics that can fight bacteria, like E. coli. The best way to pinpoint which antibiotics work is by measuring their ability to create antimicrobial agents or zones of inhibition. When a paper disc that has been saturated in an antibiotic is inserted in a solution of E.coli and medium, the zone of inhibition will be noted as the clear ring that forms around the disk. The antibiotics efficacy is then determined by measuring each disk zone of inhibition, and comparing these measurements to the zone measurements of an untreated specimen. If an antibiotic is to be deemed sufficient for treating E. coli it should show a zone of inhibition that is at least double the size of the untreated specimen.

One environment where bacteria are regularly exposed to antibiotics is in large livestock operations, where producers very often treat their cows and other animals with drugs to prevent epidemics in the unsanitary and overcrowded conditions, which are common in the livestock industry. The simple reason for this is that in the short term it is cheaper to drug up the animals with antibiotics than to keep a clean living environment for them. Another big reason for these producers to drug up the animals is the fact that feeding antibiotics to the livestock makes for larger animals. The problem occurs when bacteria in these animals survive the bombardment of antibiotics, and some always do, the

The Kirby- Bauer method is used to test antibiotics sensitivity to the microbe. Some antibiotics have broad-spectrum effect, which means they inhibit the growth of more than one microbe; while narrow spectrum only have an effective on one group of microbe. In order for this test to be effective a lawn of bacteria has to be made on Mueller- Hinton agar. This agar does two amazing things in the world of science. It contains a starch that makes it test plate transparent (easy to read results) and it control the rate of diffusion of the tested drug. Ampicillin, Gentamicin, Gentamicin, penicillin, and vancomycin are the fours types of antibiotics that were use to test the sensitivity of the microbe to them. The microbe was resistant to Ampicillin;

After 48 hours, the experimenter was able to obtain the Petri dish in order to observe what had taken place, within the nutrient agar plate, of the span of this period of time. The experimenter was able to establish that any clear areas surrounding the filter-paper disks were the zones of inhibition and they indicated that the antibiotic was able to inhibit the bacterial growth, and any cloudy areas of the agar demonstrated that bacterial growth was still able to take place within the given conditions. Thus, the larger the zone of inhibition, the more bacteria was inhibited within this specific environment. Quadrant 1 contained an Erythromycin filter-paper disk, which was able to inhibit the growth of Bacteria D. The Erythromycin filter-paper

The purpose of this project was to determine the minimal inhibitory concentration of our given antibiotic called tetracycline. Tetracycline is a bacteriostatic agent and instead of directly killing the bacteria, it prevents the growth mainly by inhibiting the synthesis of proteins. We hypothesized that the minimal inhibitory concentration for our test would range from 4 g/mL to 8 g/mL. This process spanned across four lab meetings located in a biology lab at Duncan Hall of San José State University. The first lab introduced us to sterile and plating techniques as we prepared and plated a serial

The objective of this lab was to measure the zones of inhibition of the discs that were soaked in different hand-cleansing agents/antibiotics and put in agar plates that were swabbed with Escherichia coli culture. In order to do this, we used the Kirby-Bauer method. The Kirby-Bauer method is a test of detect the antibiotic sensitivity to bacteria. The method is used by using antibacterial discs to see which bacteria are affected by those antibiotics. My hypothesis, stated before the experiment, was that penicillin will have the smallest zone of inhibition because it is an antibiotic, and it will work the best.

The independent variable for the Antibiotic Resistance Lab was the strain of E. Coli, the strain that we tested is called E. Coli K-12. The dependent variable was the amount of E. Coli that was resistant to triclosan, i.e. the size of the zone of inhibition. This lab was experimental because we were physically dealing with the variables. We created the environment for the E.Coli to either adapt to or not.

The Kirby-Bauer disc diffusion method was used to examine sensitivity of antimicrobial agents, it fast and simple way to find an antibiotic to use for a treatment of some type of infection. This method uses a plate that has been cover with the testing bacteria and small disc covered in the antibiotic to see if the bacteria is able to around the disc, it will make an even circle around the disc which is the zone of inhibition. This zone of inhibition diameter can be measured and compared to the interpretation chart to find the antibiotic sensitivity or resistance. When the zone of inhibition is very small or nonexistent this shows that bacteria is resistant to the antibiotic and will not work against this bacterial infection. If the zone is

The introduction of different antimicrobials for treating different infections exhibited the importance of having antimicrobial susceptibility testing as a repetitive method in all microbiology laboratories. In laboratories this can be possible by using antibiotic disk that will diffuse gradually into the medium where the suspected organism is located. The fundamental principle of the antibiotic susceptibility testing was already being used in microbiology laboratories over 80 years. Several chemical agents like for example antiseptics, disinfectants, and antibiotics are engaged to fight the growth of microbes. Among these, antibiotics are commonly defined as the substances that microorganisms produce like Penicillium that can kill or inhibit the growth of other microorganisms, primarily bacteria. Antimicrobial susceptibility tests (ASTs) principally measures the capacity of an antibiotic or other antimicrobial agent to prevent microbial growth in vivo.

In the experiment “Antimicrobic Sensitivity Testing: The Kirby-Bauer Method” students used six different antimicrobics to identify which antimicrobics were effective in killing four different organisms. The four different organisms that students used in this experiment were: E. coli, Proteus Vulgaris, P. aeruginosa, and S. aureus. And the six antimicrobics that students used in this experiment were: Amoxicillin, Cefoxitin, Chloramphenicol, Doxycycline, Rifampin, Vancomycin. Each organism was swabbed in a different plate of nutrients, and the six antimicrobics were placed in the plate, too. After swabbing the organism and placing the antimicrobics, the plates were incubated for forty-eight hours.

If your patient has an infection of any kind it 's critical to know which antibiotics will be effective against the particular pathogen or disease-causing agent. This means that the species and strain of bacteria, fungus, or other pathogen must be identified and he drugs that will be the most effective at clearing up the infection must be determined. The only way this can be done is by running a culture and sensitivity test. Just keep in mind that there are many different types of culture medias and hundreds of different sensitivity discs that correlate to different drugs. A negative test on one of these media plates does not meant that there is nothing there. Which is why a lot of clinics, like our own, run them in house and also send them to a lab such as Idexx to have them run a more complete test there.

Antibacterial antibiotics are a substance present in fungi, which inhibits the growth and production of bacterial infections. The discovery of the first antibiotic, penicillin, was a turning point in medical history, as illnesses that were once perceived as difficult to treat or even fatal, now had a possible treatment. After the discovery of penicillin, the misuse and overuse of antibiotics become common in many different professions. This has resulted in bacteria becoming less easily detected due to structural changes, with some even being multi-resistant, such as Methicillin-resistant Staphylococcus aureus (MRSA), Multidrug-resistant tuberculosis (MDR-TB) and Vancomycin-resistant Staphylococcus aureus (VRSA) (Williams 2014).