Antibiotic Resistance Of The Gram Negative Bacterial Species Serratia Marcescens

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.

In this lab, the organism that we have been working with is the bacterium, Serratia marcescens. S. marcescens is a member of the Enterobacteriaceae family, and tends to grow in damp environments. S. marcescens is an ideal bacterium to work with in the lab because it reproduces quicker than other bacterium. This bacterium produces a special pigment called prodigiosin, which is red in color. The prodigiosin pigment is intensified when S. marcescens is grown at higher densities. During our experiment, temperature, pH, salinity concentration and oxygen requirements were tested on S. marcescens to measure their optimal growth and prodigiosin production.

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.

Antibiotics are inarguably one of the greatest advances in medical science of the past century. Although the first natural antibiotic Penicillin was not discovered until 1928 by Scottish biologist Alexander Flemming, evidence exists that certain plant and mold growths were used to treat infections in ancient Egypt, ancient India, and classical Greece (Forrest, 1982). In our modern world with the advent of synthetic chemistry synthetic antibiotics like Erithromycin and its derivative Azithromycin have been developed. Antibiotics have many uses including the treatment of bacterial and protozoan infection, in surgical operations and prophylactically to prevent the development of an infection. Through these applications, antibiotics have saved countless lives across the world and radically altered the field of medicine. Though a wonderful and potentially lifesaving tool, antibiotic use is not without its disadvantages. Mankind has perhaps been too lax in regulation and too liberal in application of antibiotics and growing antibiotic resistance is the price we must now pay. A recent study showed that perhaps 70% of bacterial infections acquired during hospital visits in the United States are resistant to at least one class of antibiotic (Leeb, 2004). Bacteria are not helpless and their genetic capabilities have allowed them to take advantage of society’s overuse of antibiotics, allowing them to develop

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.

I discovered that my unknown organism was Serratia marcescens. This organism is gram negative and bacillus shaped. It is a member of the Enertobacteriae family. This organism appears a red blood like color when it grows on media. It is anaerobic, but can also survive under aerobic conditions. There are some strains of Serratia marcescens that are motile and have flagellum. It is able to produce the enzymes chitinase, lipase, protease, nuclease, and serrawttin. It is a non-endospore forming bacteria, chromogenic, and does not ferment lactose. (Falkiner, 1997)

Coli. The first standard E. Coli has no resistance plasmid while the second strain contains a resistance plasmid with genes protecting it from ampicillin. This standard E. Coli and pAMP (plasmid-Ampicillin) E. Coli were each streaked across plates containing the antibiotic and containing growth supportive Lurithea Broth. The purpose of this lab was to test their growth in each medium. Our hypothesis was that while the ampicillin resistant E. Coli would show growth in both LB and LB-AMP plate, the standard E. Coli would only grow in the LB plate for it contains no resistant plasmids against the

1 and 3). This antibiotic is effective against both gram positive and negative bacteria, so it would be effective against Staphylococcus epidermidis. This antibiotic is able to kill bacteria by interfering with the cell wall synthesis, weakening it, and causing its death. However, just like with Penicillin, some bacteria have become resistant to this antibiotic (6). The hypothesis stated that Staphylococcus epidermidis would be susceptible to Ampicillin because although some bacteria have become resistant this one has not (7). According to the class data, two of the tests resulted in in susceptibility, one resulted in an intermediate effect, and the rest were resistant (see Figs. 2 and 5). It seems that Staphylococcus epidermidis is in the process of becoming resistant to Ampicillin because of the varied data. However, the group data did not support the hypothesis that the bacteria would still be

The purpose of this experiment is to show how different concentrations of Ampicillin affect Escherichia Coli Growth and how the bacteria become resistant to the antibiotic drug. Through a series of steps, which involves streaking agar plates with E.coli sample and application of ampicillin to the E.coli sample on the agar plate, the experiment yields a result that supports the hypothesis. The hypothesis acclaims that ampicillin would affect the growth of E.coli; measuring the zone of inhibition approves the claim in the experiment. The measurements of the zone of inhibition indicate that the generation of E.coli expands as the radius reduces. The reduction of the radius shows the E.coli population is reducing and becoming resistant. In other

Serratia Marcescens are rod-shaped bacteria in the family Enterobacteriaceae. They are a group of Gram negative bacterium that are opportunistic human pathogens humans(Petersen and Tisa 2013). The genus Serratia has 14 recognized species with 2 subspecies(Mahlen 2011). S. marcescens cause in hospital-acquired infections (HAIs) (Sydnor and Perl 2011) and diarrhea associated with HIV/AIDS. Serratia can survive in different environments like water, soil, and the digestive tracts of various animals Petersen and Tisa 2013). In the gastrointestinal tract, it can destroy microvilli and vacuolization. It can also cause nosocomial infections like catheter-associated bacteremia, urinary tract infections respiratory tract infection, meningitis, bacteremia

Antibiotics are amongst the most important medical discoveries and their introduction represents a remarkable success story (Hedin, 2011). The term antibiotics literally means against life (Walsh, 2000). Thus antibiotics can be used against any microbe such as bacteria, viruses, fungi, and protozoa. However, some people use the term to only apply to bacteria, but in this paper, the more appropriate term will be used.

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 aim of this experiment is to follow the growth of Serratia marcescens in nutrient broth at 37oCby recording the changes in turbidity (cloudiness) by measuring the absorbance of visible light (600 nm) and also to prove that there is an increase in the cell number and not just in mass during the growth.

Dependent Variable: The color change of the bacteria Serratia Marcescens from red to white and the survival of the bacteria.

The main objective of this experiment is to investigate the effect of different types of antibiotics on bacteria Bacillus subtilis and Escherichia coli. Some of the main methods used in this experiment