Tetracycline and Chloramphenicol Against Serratia Marcescens

6. The disks in the 0.00% solution were transferred to an agar plate held next to the blue flame using the sterilized tweezers. Excess disinfectant was removed from the disks by wiping on the side of the well of the spotting tile. When the 5 disks were positioned (refer to Figure 1 below) the lid was replaced and sticky taped down. A label was added indicating the concentration of disinfectant.

6 petri dishes were labeled, 3 petri dishes P 105 B, P 106 B, P 107 B, and the other 3 petri dishes P 10 K, P 102 K, P 103 K and they were set aside. A series of dilutions for the 1x bacteriophage T4 rII

Drug therapy relies on the principle of selective toxicity, where the effects of the drug are only harmful towards the foreign parasite and not at all to the host. By comparing the effects of different drugs on various parasitic organisms we are able to distinguish the type of disease or infection that is present as well as the mechanism of action that takes place by each drug in question. The drugs may function by interacting with enzymes such as transpeptidase and thymidylate synthetase, for example Penicillin and 5-FU function respectively. The effectiveness can be quantified by measuring the zones of inhibition created by the drug on the plate of the bacteria or fungus. This is the area where there is no growth due to the action of the drug. The discovery that the Micrococcus-luteus is classed as a bacteria was made apparent due to Penicillin’s success in inhibiting it’s growth. The action of the Amphotericin solely on the Pythium, gives reason to believe that it can be grouped with fungal growths.

Although some agar plates were hard to see if the streptomycin had a definitive zone of inhibition. Ampicillin, erythro-mycin, penicillin, sulphafurazole was ineffective with no inhibition zone.

Abstract-The gram-negative bacteria Serratia marcescens has gained attention in recent years for its tendency to cause nosocomial infections in humans, as well as its development of antibiotic resistance. Antibiotic resistance in a bacterium that is harmful to humans can be concerning as it can result in infections that are difficult to treat. In order to find out more about the growing antibiotic resistance of S. marcescens, this experiment used the disc diffusion method to test the susceptibility of S. marcescens to two varieties of antibiotics that were known to have success against some gram-negative bacterium: streptomycin and ampicillin. These antibiotics were, respectively, an aminoglycoside and a beta-lactam. The experiment tested which of the two that S. marcescens had developed more of a resistance to. The zones of inhibition of the discs were significantly larger for discs treated with streptomycin compared to discs treated with ampicillin. This led to the conclusion that S. marcescens is less resistant to streptomycin than to ampicillin.

70µL of competent E.coli are added to both test tubes; pUC18 and Lux (Alberte et al., 2012). Both test tubes are then tapped and placed back into the ice bath for 15 minutes. While waiting, another test tube is obtained, filled with 35µL of competent cells and labeled NP for no plasmid. A water bath is preheated to 37 degrees Celsius and all three labeled test tubes are inserted into the bath for five minutes (Alberte et al., 2012). Using a sterile pipet 300µL of nutrient broth are inserted into both the control and Lux test tubes and 150µL are inserted to the no plasmid test tube to increase bacterial growth. All three test tubes are then incubated at 37 degrees for 45 minutes. Six agar plates are obtained and labeled to correspond each test tube, three of the plates contain ampicillin. A pipet is used to remove 130µl from each test tube containing a plasmid and insert it into the corresponding agar plate. For this, a cell spreader is first

Lab Day 1: After receiving my unknown bacteria, I streaked a TSA plate and incubated at 37°C for 48 hours. I then picked a single colony from the plate with my sterile loop and streaked a TSA slant and labeled it “Working Stock”. I did the same with another TSA slant and label the second one “Back-up Stock”. This would be the samples I used to complete the following procedures through the next four weeks to determine my unknown bacteria.

This experiment can be enhanced in many ways. The amount of alcohol used as treatments could be lessened to measure the viability of A. salina more accurately. The amount of cysts in each Petri dish was not consistent because there

There were two tubes used in this process: the tube that contained the primary culture and the tube that contained the nutrient agar where the unknown bacteria would grow. First, the inoculating loop was flamed. After removing the caps of both the test tubes, they were flamed to prevent contamination of the unknown bacteria. The inoculating loop was cooled for a few seconds and was then placed into the test tube containing the bacteria. The inoculating loop with the bacteria was placed into the nutrient agar test tube for cultivation. Before the test tubes were capped, they were flamed once again. Also, isolation of the unknown bacteria had to completed. Nutrient agar was placed in the petri dish, and was left to gel for a few minutes. After the agar gelled, the inoculating loop was used to acquire bacteria and streak the unknown onto the plate for

At this point in the experiment, we labeled two Luria Bertani nutrient-rich agar plates with the strain name, group initials, date, and which dilution it was. From there we were able to pipet 100 µL of our final dilution onto one of the nutrient-rich L medium agar plates. After 100 µL of our dilution was placed in the middle of the plate, we flamed the L-shaped spreader by dipping it into 95% ethanol and then placing it over a Bunsen Burner flame. My lab partner and I waited for the flame to go out and cool off before placing it on our bacteria. After letting it cool, we were able to move the L-spreader onto the bacteria and spread the bacteria all over the agar plate. After spreading the bacteria, the L-spreader was then sterilized again before putting it down on the

In the first part of the experiment, we plated donor bacteria, which was chloramphenicol resistant, on a Nal plate. Because no donor bacteria would grow on a Nal plate, this was a way of ensuring that the sample of donor E. Coli bacteria was pure.

In the 10-3 pasteurized sample, the plate exhibited 71,000 cells/mL. The results of the additional dilution samples contained too few colony forming units to count. However, in the 10-7 dilution, although the plate demonstrated 12 colonies, there should have been no colony forming units on this plate. The reasons for this could have been that this sample was contaminated from “double-dipping” the sample before dispensing it onto the plate or when using the pipette, it mistakenly was inserted in a higher concentration sample and then immediately to a lower concentration sample before it was dispensed onto the plate.

It is found everywhere in the environment but it flourishes in damp conditions like bathrooms, where it is commonly found growing on tile grout, shower corners, toilet water line, and basin, where it manifests as a pink discoloration and slimy film feeding off phosphorus-containing materials or fatty substances such as soap and shampoo residue (Serratia marcescens. (n.d.). The topmost risk factor for Serratia marcescen infection is long drawn out hospitalization. Those who have a weak immune system are more prone to the development of these nosocomial infections. Important triggering factors include: intra peritoneal, intra venous or urinary catheters, instrumentation of the respiratory tract, such as bronchoscopy and ventilators, intra articular injections, trauma to the skull, neuro-surgery, epidural injection, or a lumbar puncture. (Serratiamarcescens.net: What Is Serratia Marcescens? (2016)). Most Serratia marcescen strains are resistant to several antibiotics because of the presence of R-factors, which are a type of plasmid that carry one or more genes that encode

Serratia marcescens is a rod-shaped gram-negative bacteria and a facultative anaerobe that can grow in the presence and absence of oxygen. It can thrive in water and in the digestive tract of some animals. It is commonly found in homes in the bathtubs and shower wall. Serratia Marcescens is a rare cause of Endogenous Bacterial Endophthalmitis. Endogenous Bacterial Endophthalmitis is an uncommon but severe infection that results in blindness or visual compromise in up to 75% of affected patients. Endogenous endophthalmitis is caused by hematogenous spread of bacteria to the eye from an extraocular focus, whereas the more common exogenous endophthalmitis occurs after ocular trauma or surgery. This infection mostly occurs in the right eye which

Examples of antibiotics that are commonly used in infection treatment include: gentamycin, tetracycline, streptomycin, and carbenicillin