PartI- Measuring Resistance We\'re looking for Katelyn was excited to start her
ID: 53389 • Letter: P
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PartI- Measuring Resistance We're looking for Katelyn was excited to start her summer job in her microbiology professors research laboratory. She had enjoyed Dr. Johnson's dlass, and when she saw the flyer recruiting undergraduate lab assistants for the summer, she had jumped at the opportunity. She was looking forward to making new discoveries in the lab. Dr. James Johnson On her first day, she was supposed to meet with Dr. Johnson to talk about what she would be doing. She knew the lab focused on antibiotic resistance in Staphylococcus aureus, espe cially MRSA (methicillin-resistant S aureus). She still remembered the scare her family had last year whct her little brother, Jimmy, got so sick. Hed been playing in the neighborhood playground and cut his lip when he fell off the jungle gym. Of course he always had cuts and scrapes-he was a five-year-old boy! This time though his lip swelled up and he developed a fever. When her mother took him to the doctof, the pediatrician said the cut was infected and had prescrib cephalothin, an antibiotic related to penicillin, and recommended Alushing the cut regularly to help clear up the infectio Two days later, Jimmy was in the hospital with a fever of 103 F, coughing up blood and having trouble breathing. Th emergency room doctors told the family that Jimmy had developed pneumonia. They started him on IV antibiotics including ceftriaxone and nafcillin, both also relatives of penicillin. It was lucky for Jimmy that one of the doctors It was lucky for Jimmy that one of the doctors decided to check for MRSA, because that's what it was! MRSA is resistant to most of the penicillin derivatives. Most cases of MRSA are hospital-acquired from patients who are already susceptible to infection, but the ER doctor explained that community-acquired MRSA was becoming more comm The doctor then switched the treatment to vancomycin, a completely different kind of antibiotic, and Jimmy got better on. uickly after that. Katelyn had dropped Jimmy off at swimming lessons just before coming to work at the lab. As she waited in the hallway for Dr. Johnson, she hoped that she would be at least a small part of helping other people like Jimmy deal th these scary resistant microbes. She was surprised when the professor burst out of the lab, almost running into her. Hi Katelyn, I'm really sorry but I have to run to a meeting right now-t Dr. Johnson said as he rushed down the hallway with a stack of folders. I'm really sorry but I have to run to a meeting right now -they sprung it on me last minute. There are a in the incubator right now that need their zones of inhibition measured. I'll be back in a few hours," dug out her old lab notebook to look up what she was supposed to do. She found the lab where she and her Katelyn fellow students had examined the antimicrobial propertiés of antibiotics using the Kirby-Bauer disk diffusion tech nique. Looking at the plates Dr. Johnson had told her about, she saw they had all been "lawned," or completely coated with microbes to make a thick hazy layer over the agar surface. She could also sce paper disks with letters on them, and some of the disks had clear zones around them where the microbe had been inhibited (ig. 1). Her notebook explained how to measure the zone of inhibition around the disks (Fig. 2)Explanation / Answer
The Graph for S. aureus:
The Graph for MRSA:
1)
The experimental question is that, which antibiotic is effective against S. aureus and MRSA.
2)
The hypothesis is that MRAS is less susceptible to the antibiotics than S. aureus. This is because MRSA is most resistant strain of S. aureus.
3)
If my hypothesis is correct, then MRSA has less zone of inhibition for all antibiotics and S. aureus has more size of zone of inhibition for all antibiotics compared to MRSA.
4)
Yes, from the experimental data, S. aureus has less resistance to all most all antibiotics, but MRSA has more resistance, except for antibiotic VA.
5)
The antibiotics were most effective against S. aureus:
The antibiotics were most effective against MRSA:
6)
By comparing effectiveness of antibiotics against S. aureus and MRSA, all four antibiotics have shown effectiveness against S. aureus in an equivalent way. However, the antibiotic VA only has shown effectiveness against MRSA and remaining three have low effectiveness.