Antibiotic Resistance Lab Report PDF

Preview

Summary

Antibiotic resistance lab report...

Description

Running Head: Antibiotic Resistance using the Kirby-Bauer Method 1

Antibiotic Resistance using the Kirby-Bauer Method

By Student Name

Course Name Lab Section Instructor's Name Due Date

Antibiotic Resistance using the Kirby-Bauer Method 2

Abstract This experiment provided a method for determining antibiotics' effectiveness through measuring inhibition zones on an inoculated agar plate. Antibiotics mainly work by inhibiting the growth of the disease-causing organisms, primarily bacteria. The experiment used the Kirby-Bauer procedure, which involves inoculation of medium with the bacterial species, placement of antibiotic disks, incubation, and assessment of the experiment results. This experiment showed that antibiotics are most effective with gram-positive bacteria like Staphylococcus aureus, which has thick layers of peptidoglycan.

Antibiotic Resistance using the Kirby-Bauer Method 3

Introduction Antibiotics are chemical substance that kills microorganisms by inhibiting their growth. Some antibiotics can be made synthetically, while other organisms form some. Antibiotics are beneficial since they disrupt cell activities; that is, they affect the synthesis of the cell wall, nucleic acid formation and breaking up, synthesis of proteins, and reproduction process. (Bren, 2002) Over the past decades', antibiotics have been popular and globally used. However, their efficiency and success have steadily dropped. This is due to the resistance that occurs either from drug misuse or bacterial mutation. ( Kleyn and Bincknell, 2007) Bacterial mutations are genetic changes n the genome of the bacteria that enable the bacteria to fight the antibiotic. Therefore, microorganisms can develop resistance to some antibiotics naturally. Consequently, it is essential to apprehend how antibiotics' effectiveness is lost since they are our only defense against pathogens. This experiment aims to give an insight into the resistance and susceptibility of microorganisms to certain antibiotics. Four, unlike bacterial organisms, Staphylococcus aureus, Pseudomonas aeruginosa, Bacillus subtilis, and Micrococcus luteus, were tested with dissimilar antibiotics to distinguish the effectiveness of every antibiotic. ( Talaro, Cowan and Chess, 2009) It is imperative to test the four bacterial organisms with different antibiotics. Most of these organisms are found in the skin's body and surface, and antibiotics are the regular treatments given to the sick. Recognizing and appreciating antibiotics' effectiveness is essential in modifying existing antibiotics and developing new and more effective antibiotics. It was hypothesized that that antibiotics are most effective with gram-positive bacteria like Staphylococcus aureus, which has thick layers of peptidoglycan.

Antibiotic Resistance using the Kirby-Bauer Method 4

Methods The experiment started by setting up the work table and collecting all the materials needed for the experiment. Then all the agar plates were labeled with the number and bacterial species to be tested. The agar plates were then inoculated with the bacteria to be tested. Once all the disks were inoculated, the antibiotic disks were dispensed evenly onto the agar surface. The plates were then positioned in proper incubators, fixed them upside down, and then removed once the incubation process was complete. The diameter of the zones of the inhibition around the disks was measured for Staphylococcus aureus. The diameter of each inhibition zone was measured in millimiters using a ruler and the results recorded in a table. The process was then repeated for Pseudomonas aeruginosa, Bacillus subtilis, and Micrococcus luteus. The results were then analysed using the Kirby Bauer Table of Interpretive Standards. The assessment did not include MJ31 or GEN since they are not available on our Kirby Bauer Table of Interpretive Standards. Results

Antibiotic (Antimicrobial Agent)

Staphylococcu s aureus Diameter(mm)

Chloramphenicol 25 Erthromycin 15 Nalidixic Acid 15 Cefdinir 16 Streptomycin 11 Ampicillin 30 Vancomycin 17 Figure 1.0 Individual Results

Pseudomonas aeruginosa Diameter(mm ) 2 0 13 0 0 8 0

Bacillus subrilis Diameter(mm)

Micrococcus luteus Diameter(mm)

22 10 6 0 5 25 0

25 20 10 12 6 30 12

Ampicilin formed the largest inhibition zone in S.aureus while streptomycin formed the smallest. Erythromycin, cefnidir and streptomycin did not form inhibition zones in P.

Antibiotic Resistance using the Kirby-Bauer Method 5

aeruginosa while nalidixic acid formed the largest inhibition zone. For B. subrilis, ampicillin formed the largest inhibition zone while cefnidir and vancomycin did not form inhibition zones. Streptomycin had the smallest inhibition zone in M. luteus while chloramphenicol had the largest. This experiment's results helped assess the resistance and susceptibility of the bacterial species to the antibiotics tested. Discussion All the plates that were observed enclosed resistant and susceptible cultures of bacteria. Some plates of antibiotics had large inhibition zone surroundings, and some did not have. Antibiotics that had the largest inhibition zones were the most efficient. Cefdinir and Vancomycin were the least efficient antibiotics since they did not create any inhibition zone around B. subrilis and P. aerugonisa. This might be because of the drug's overuse making microorganisms quickly mutate to it. Some organisms are also resistant because they create an enzyme, penicillinase, which destroys penicillin. Erythromycin and Streptomycin created an inhibition zone around S.aureus, M. luteus and B.subrilis. Still, they did not form inhibition zones in P.aeruginosa since P. aeraginosa has a thicker outer membrane, which stops the entry of antibiotics, making it more resistant. Notably, only Ampicillin, Nalidixic Acid and Chloramphenicol created an inhibition zone around P. aeruginosa, suggesting that they have a higher capability to penetrate the bacteria's thick outer layer, making it the most efficient drug for P.aeruginosa. Ampicillin was the most efficient drug for B. Subrilis and S.aureus. Therefore the most resistant microorganism was P.aeruginosa, while the most susceptible organism was S. aureus. This experiment's results supported the hypothesis that antibiotics are most effective with gram-positive bacteria like Staphylococcus aureus, which has thick layers of peptidoglycan. The problem that arose during the procedure was that some

Antibiotic Resistance using the Kirby-Bauer Method 6

plates fell off the agar in the incubator; this led to the skewness of the results since the felled plates' observations could not be recorded. In conclusion, the development of new antibiotics is vital in the war against diseasecausing microorganisms. This is because bacterial species can mutate into more resistant strands after contact with a specific antibiotic for a long time. Antibiotics, therefore, lose their effectiveness when used in high doses for an extended period.

References Bren, L. (2002). Battle of the bugs: fighting antibiotic resistance. FDA consumer, 36(4), 28– 34. Kleyn, J., & Bicknell, M. (2007). Microbiology experiments. McGraw-Hill Higher Education. Talaro, K., Cowan, M., & Chess, B. (2009). Foundations in microbiology. McGraw-Hill.

Antibiotic Resistance using the Kirby-Bauer Method 7

Appendix: Plate Results Figure 2.0 Plate Results for Staphylococcus aureus

Antibiotic Resistance using the Kirby-Bauer Method 8

Figure 3.0 plate results for Pseudomonas aeruginosa

Figure 4.0 Plate Results for Bacillus subtilis

Figure 5.0 Plate Results for Micrococcus luteus

Antibiotic Resistance using the Kirby-Bauer Method 9...