Essay About Microbiology Unknown Lab Report And Series Of Tests

Microbiology Unknown Lab Report – Lab Report – Madelyn Barr
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Microbiology Unknown Lab Report
Madelyn BarrOctober 11, 2017Unknown I LabUnknown #30Unknown I Lab ReportAbstract        The “Unknown I Lab” was performed in order to evaluate the student’s ability to identify an unknown organism based on a series of tests and observations. Accurately identifying microorganisms is important for a variety of reasons. One of the most medically relevant reasons is being able to determine the causative agent of a patient’s illness so that you can treat it properly. I performed four tests in order to confidently classify my unknown organism. I began with a blood agar hemolysis reaction and then utilized single colonies from that plate to perform a Gram stain, catalase test, and a bile esculin test. A gamma-hemolytic blood result, positive Gram stain with cocci in chains result, negative catalase test, and positive bile esculin test led me to believe that unknown #30 is Enterococcus faecalis.Introduction        The purpose of this lab was to determine the identity of my unknown organism. I had unknown #30. The possible organisms available were Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pyogenes, Enteroccus faecalis, Streptooccus pneumoniae, and Streptococcus thermophiles. Staphylococcus aureus is present in most environments frequented by humans and is also readily isolated from fomites. Predispositions to infection include poor hygiene and nutrition, tissue injury, preexisting primary infection, diabetes, and immunodeficiency. S. aureus can cause localized cutaneous, systemic, and toxigenic infections. Localized cutaneous infections include folliculitis, furuncles, carbuncles, and impetigo. Osteomyelitis and bacteremia comprise the possible systemic infections. Toxigenic diseases include food intoxication, Staphylococcal scalded skin syndrome, and toxic shock syndrome. Staphylococcus epidermidis often lives on skin and mucous membranes of the human body. It is often the causative agent of endocarditis, bacteremia, and urinary tract infections (UTIs). Streptococcus pyogenes is the most serious streptococcus pathogen. Humans are its only reservoir, where it inhabits the throat and nasopharynx. S. pyogenes can enter through the skin and pharynx by way of contact, droplets, food, or fomites. Children are the predominant group affected by this organism. The most common diseases among children are impetigo and streptococcal pharyngitis. If left untreated, scarlet and rheumatic fever, septicemia, pneumonia, streptococcal TSS, and acute glomerulonephritis can occur. Enterococcus faecalis, otherwise known as Group D Streptococcus, is a normal colonist of the human intestine. It can cause opportunistic urinary, wound, and skin infections. Immunodeficient individuals are often susceptible to infection. Infections by Streptococcus pneumoniae usually occur when bacteria cells are aspirated into the lungs. Pneumococci multiply and induce an overwhelming inflammatory response. S. pneumoniae causes diseases like pneumonia and otitis media. Streptococcus thermophiles often inhabits the oral cavity, skin, nose, and genital tract. It is not very invasive, so dental and surgical procedures facilitate entrance. It causes a variety of diseases such as bacteremia, meningitis, abdominal infections, and tooth diseases. The most serious one is subacute endocarditis. Because S. thermophiles can colonize the heart by biofilm production, people with preexisting heart disease are at high risk for infection. There were multiple tests available to identify which organism I had. These included blood agar hemolytic reactions, Gram stain, catalase, coagulase, bacitracin and optochin susceptibility, bile esculin, bile solubility, and salt tolerance.Materials and Methods         At the beginning of this lab, I randomly selected an unknown broth labeled #30, which contained one organism. I was instructed to streak my broth onto a blood agar plate using a metal loop.  The plate was incubated overnight at 37°C and evaluated the following lab for a hemolytic reaction. Blood agar plates contain 5% sheep red blood cells and 95% trypticase soy agar (TSA). A complete lysis of the red blood cells indicates β-hemolysis, where a clear zone is observed around the organism’s growth. Hemolysins produced by the bacteria break down the red blood cells. Partial lysis is an α-hemolytic reaction. There is a breakdown of hemoglobin to met-hemoglobin, which is then reduced and causes a greening of the blood around the colonies. No lysis of blood indicates γ-hemolysis, where there is growth but no clear zone nor green color. The next test I performed was a Gram stain. I began by selecting a single colony from the blood agar plate and smearing it onto a glass slide. After staining the smear, I observed my organism under the microscope. Purple cells indicate Gram positive organisms while red cells indicate Gram negatives. Gram stains also display the morphology ad arrangement of the cell. All of the available organisms were Gram positive and cocci-shaped. Staphylococci are arranged in grape-like clusters and streptococci are in chains. The third test I performed was a catalase test to differentiate between the staphylococci and streptococci families. This is done by picking up a single colony from a TSB plate, smearing it onto a glass slide, and dropping hydrogen peroxide onto the smear. The formation of gas bubbles is a positive result. No gas bubbles is negative. All staphs are catalase positive because they contain cytochromes in their electron transport systems, which contain catalase. Hydrogen peroxide is broken down by catalase into water and oxygen, producing gas bubbles. It was important that I plated my organism onto a TSB plate, allowed it to incubate at 37°C for 24 hours, and picked a colony from there instead of the blood agar plate because red blood cells contain cytochromes, which could lead to a false positive. My final test was a bile esculin test. A bile esculin slant contains peptone, beef extract, bile, esculin, ferric citrate, agar, and distilled water. This medium tests for organisms that grow in the presence of bile and hydrolyze esculin. A black complex is produced when the bacteria hydrolyze esculin to esculetin, which then reacts with ferric ions in the medium. Growth and esculin hydrolysis indicate positive, while negative yields no growth or black complex. This test is important for identification of Enterococcus faecalis. I fishtailed my organism onto a bile esculin slant and incubated it at 37°C for 24 hours.

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“Microbiology Unknown Lab Report” EssaysForStudent.com. 02 2018. 2018. 02 2018 < "Microbiology Unknown Lab Report." EssaysForStudent.com. EssaysForStudent.com, 02 2018. Web. 02 2018. < "Microbiology Unknown Lab Report." EssaysForStudent.com. 02, 2018. Accessed 02, 2018. Essay Preview By: Madelyn Barr Submitted: February 21, 2018 Essay Length: 1,384 Words / 6 Pages Paper type: Lab Report Views: 357 Report this essay Tweet Related Essays Unknown Lab Report for Microbiology There are many reasons for identifying an unknown bacterium. The reasons range from medical purposes, such as determining if the unknown could cause ailments in 470 Words  |  2 Pages Unknown Lab Report Grading Guidelines Cover 343 Words  |  2 Pages How to Write an Unknown Lab Report in Microbiology HOW TO WRITE AN UNKNOWN LAB REPORT IN MICROBIOLOGY GENERAL Unknown reports in microbiology are written in scientific format. Scientific writing is written differently from 1,731 Words  |  7 Pages Unknown Bacteria Lab Report Introduction The purpose to this lab was to isolate and identify two unknown bacteria from a mixed culture provided to us by our instructor. This 1,503 Words  |  7 Pages Similar Topics Lab Report Write Formal Lab Write Report Get Access to 89,000+ Essays and Term Papers Join 209,000+ Other Students High Quality Essays and Documents Sign up © 2008–2020 EssaysForStudent.comFree Essays, Book Reports, Term Papers and Research Papers Essays Sign up Sign in Contact us Site Map Privacy Policy Terms of Service Facebook Twitter