Klebsiella BacteriaThis print version free essay Klebsiella Bacteria.
Autor: reviewessays 05 December 2010
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A very important technique in Microbiology laboratories is identifying unknown bacteria cultures. Unknown identification is used for practical purposes, such as diagnosing diseases or determining treatment of an infection. Microbiologists identify unknown bacteria to determine new and emerging infectious diseases and current diseases to determine if any kind of treatment or antibiotics can be used. Some bacteria do not have distinguishing morphological features, so there are different kinds of test that can be performed to distinguish the differences of bacteria. The types of identification methods used to identify bacteria are cell wall composition, differential staining, biochemical testing, and morphology. Some other tests that are used to identify bacteria are serological testing, flow cytometry, DNA fingerprinting, Ribosomal RNA sequencing, and phage typing.
Determining the chemical composition of the cell wall is an important aspect in identifying unknown bacteria, but it corresponds with differential staining. In differential staining the one type of stain that is very useful is the gram stain. Gram stains are done in order to distinguish bacteria based on the composition of cell wall they have. They are two types of gram stains the gram-positive and gram-negative. The gram-positive bacteria cell walls mainly consist of many layers of peptidoglycan, which forms a thick rigid structure. Cell walls of gram-positive bacteria contain teichoic acids, which primarily consist of an alcohol and phosphate. The teichoic acids provide much of the cell wallâ€™s antigenic specificity making it possible to identify bacteria by certain laboratory tests. The gram-negative bacteria consist of one or a very few layers of peptidoglycan and an outer membrane. The outer membrane consists of lipopolysaccharides, lipoproteins, and phospholipids. The polysaccharide portion is composed of sugars that function as antigens and are useful in distinguishing species of gram- negative bacteria. Based upon the characteristics, microbiologists perform gram stains to characterize bacteria in one of the groups.
Morphology is useful in identifying bacteria because it tells the shape and arrangement of the bacteria. You can also determine if your organism possesses flagella or endospores. Biochemical testing provides insight into a species niche in the ecosystem. Enzymatic activities are used to differentiate bacteria. Biochemical test are used to find out the oxygen requirements for your bacteria, which are also very helpful in identifying bacteria.
Serological testing differentiates among microbial species and strains within species. This test also screens bacterial isolates for possible similarities. This test detects serum antibodies or antibody-like substances that appear specifically in association with certain diseases and bacteria. Flow cytometry is used to identify bacteria in a sample without culturing the bacteria. The simplest method detects the presence of bacteria by detecting the difference in electrical conductivity between cell and surrounding medium. DNA fingerprinting is used to determine the source of hospital-acquired infections. The restriction enzymes enable researchers to compare the base sequences of different organisms. The number and sizes of restriction enzymes provide information about their genetic similarities and differences. Ribosomal RNA sequencing determines the diversity of organisms and their phylogenetic relationships. All cell contain ribosomes. Related organisms will have fewer different bases in their rRNA than organisms that are distantly related. The RNA genes have undergone few changes over time. The phage-typing test determines which types of phages a bacterium is susceptible to. The phages are able to infect and lyse the bacterial cells. This aids in the prediction of the source of infection.
I have obtained a great deal of knowledge with working with an unknown culture. I was not aware of all the different type of tests that aid in identifying bacteria. Since I plan to enter the medical field once I graduate. This experience will be very beneficial to me in the future by having the experience to work and perform the test.
Working in the hospital is a very interesting job, the constant care and treatment of patients is my daily routine. I enjoy working with patients of all different age groups. One patient that had a great impact on me was Mrs. Jennifer House. Mrs. House was brought into the hospital a 56-year-old female a prior intravenous heroin user, history of hypertension, renal failure and obstructive respiratory disease. She also has a history of diabetes. Her symptoms consisted of a high fever, chills, and flu like symptoms. Jenniferâ€™s immune system was compromised due to the fact she is a recovering heroin addict. Two days after receiving a catheterization Jennifer complained of a burning sensation during and after urination. She experienced a clean catch urine sample. Inserting a catheter into the urethra performed this test. I suspected Jennifer had contracted a urinary tract infection. My job was to find out what was causing her illness.
The first test I performed was the gram stain. The gram stain test is done to identify if the cell wall is gram-positive or gram-negative. The next test I performed was the starch hydrolysis test and the OF-glucose test. The starch hydrolysis test will show if the microbe can degrade starch by leaving a clear zone around the bacteria. In the OF-glucose test is determines if your microbe metabolized glucose through oxidation or fermentation or neither by using an open tube and a closed tube. Having an indicator color of yellow in an open tube this is due to the oxygen, which produces acid. Fermentation has occurred if the indicator turns yellow in both tubes.
The next series of test performed was the fermentation test and the MRVP test, which stands for Methyl Red, and Vogues-Proskauer test. In the fermentation test, this test is performed to determine if your organism has acid or gas present based upon the fermentation of dextrose, lactose, and sucrose. The methyl red test is used to maintain stable end products of glucose fermentation. A positive methyl red test is indicated by the presence of a red color and a negative test is indicated by a yellow color. Vogues-Proskauer test is used to detect the presence of acetoin. A positive V-P test is indicated by a pink color and a negative test is indicated by no color change. If you have a positive methyl red test then your V-P test should be negative and vice versa.
The next six tests that were performed were the gelatin hydrolysis, urea agar, litmus milk, phenylalanine deaminase, hydrogen sulfide, and the MIO test. In the gelatin hydrolysis this test is used to see if your organism can hydrolyze gelatin. A negative test is indicated by solid gelatin. A positive test for gelatin will become liquefied. The urea agar test detects for the enzyme urease, which produces ammonia. The positive test result in changing the pH of the medium that turns the indicator a fuchsia color. The litmus milk test detects five different elements. The elements that you are testing for are peptonization, the protein casein has been hydrolyzed and the medium will turn clear since there are soluble amino acids and peptides that have been broken. If acid is present, the medium will turn light pink because lactose fermentation has occurred. If alkaline is present, the medium will turn purple because of amino acid catabolism. The overproduction of acid causes coagulation. Some other organisms can reduce litmus, and the bottom of the tube will turn white. The next test was phenylalanine deaminase test. This test consists of the removal of an amino group. This test detects the deamination of phenylalanine using a ferric ion complex. A positive test will result in a green color. In the hydrogen sulfide test, peptone iron is used to determine if hydrogen sulfide is produced. When hydrogen sulfide gas is produced the sulfide reacts with the metal salt and produces a black precipitate. If the agar turns black the bacteria is positive for hydrogen sulfide production. The next test is the MIO test that determines motility, indole production and ornithine decarboxylase activity. The presence of growth diffused throughout the tube shows your organism is motile. Indole detects if bacteria has the ability to breakdown tryptophan to indole. It is indicated by a red color known as Kovacs reagent. Ornithine decarboxylase is indicated by a purple color because of the removal of carbon dioxide.
The next tests performed were the catalase test and oxidase test and requirements in thioglycollate broth and the nitrate reduction test. The catalase test is used to detect the presence of the enzyme catalase that is broken down from hydrogen peroxide to oxygen and water. A positive test is indicated by the presence of bubbles on the bacteria when contacted with hydrogen peroxide. The oxidase test is used to detect the presence of cytochrome c. A positive oxidase test is indicated by a pink color within a minute. Some bacteria have cytochrome c but they are still oxidase negative. The thioglycollate broth test is used to determine the oxygen requirements for the bacteria. Some bacteria can be aerobic or anaerobic based upon their use of oxygen. The last test done was the nitrate reduction test. This test is used to determine if the bacteria can reduce nitrite to nitrogen gas. The nitrate medium contains potassium nitrate as the substrate. If the bacteria reduce the nitrate to nitrite, the nitrite will react with added reagents sulfanilic acid and a-naphthylamine to produce a red color. If no color is produced, this can indicate two reactions: the nitrate was not reduced or the nitrate was reduced even further to compounds other than nitrite. In order to distinguish between the negative reaction and the complete reduction, zinc dust is added. If nitrate remains in the medium, zinc will reduce it to nitrate, and a pink color is observed. This is a negative reaction. No color change after zinc is added means that nitrate has been reduced to compounds other than nitrite.
After the entire test had been completed and the results were taken, I had to analyze my data. I informed Jennifer that she had contracted a urinary tract infection and we had to determine the actual cause of the bacteria. The first step was determined by the gram stain reaction. I knew that I was dealing with a gram-negative rod bacterium. I performed my research in the Bergeyâ€™s Manual of Determinative Bacteriology. I was able to observe all the different types of bacteria of gram-negative rods and start eliminating bacteria. The bacteria did not hydrolyze starch and according to the results of the OF-glucose test the bacteria was a fermenter and it was also non-motile. The methyl red test produced a pinkish color, which resulted in a positive result. The V-P test resulted in a negative result. The gelatin hydrolysis was negative also. The urea agar was positive and the litmus milk test was positive for acid. The phenylalanine deaminase, ornithine decarboxylase and hydrogen sulfide test were negative. The bacterium was able to reduce nitrate. According to the thioglycollate broth test, I was dealing with a facultative anaerobe. I was able to narrow the bacteria down to Klebsiella oxytoca or Klebsiella pneumoniae. The test that determined the distinguishing difference between these bacteria was the indole production test. The test was positive for indole production. I was able then to determine the bacteria was Klebsiella oxytoca. I was able to inform Jennifer what was responsible for her infection and information on the type of antibiotic treatment.
Klebsiella is a gram-negative rod and can form pairs or short clusters. It is part of or normal flora. They live in the inside of our gastrointestinal tracts. It is in our colon to keep us healthy. Once it escapes the gut it can become a nasty bacteria. They are opportunistic pathogens that can cause bacteremia, pneumonia, and urinary tract infections. The bacteria cause nosocomial infections in urological, diabetic and compromised immune system patients. Common sites for nosocomial Klebsiella infections include the urinary tract, lower respiratory tract, and surgical wound sites. Clinical syndromes caused by these bacteria include pneumonia, thrombophlebitis, cholecystitis, diarrhea, upper respiratory tract infection, osteomyelitis, and meningitis. The large polysaccharide capsule gives rise to large mucoid colonies, especially on a carbohydrate-rich medium. These characteristics distinguish them from other Enterobacteriaceae. They are more than 80 capsular antigens that can be used to serotype Klebsiellae.
Cephalosporin and Ciprofloxacin are antibiotics that can be used to treat a Klebsiella oxytoca infection. Cephalosporins are used to treat infections in different parts of the body. The mode of action for this antibiotic is that it inhibits cell wall synthesis; they remove the side chains and stop the synthesis of the molecule. They are resistant to penicillinases and are effect against more gram-negative bacteria than natural penicillin. Patients prefer oral administration and some newer cephalosporins allow this. Some cephalosporins can cause false positive results on urine sugar tests for diabetes. Jennifer is a diabetic if she uses this antibiotic she going to adjust her diet for the medication. This can be take on and empty stomach or with food.
Ciprofloxacin is used to treat infections of the skin, lungs, and caused by susceptible bacteria. Ciprofloxacin is also frequently used to treat urinary infections. The mode of action for this antibiotic is it interferes with the inhibitors of nucleic acid synthesis. Although this medicine can be taken with meals, it is best to take ciprofloxacin on an empty stomach. One hour before or two hours after meals is the normal preferred time. Make sure you stay well hydrated while taking ciprofloxacin. Drink several glasses of water a day. This helps to prevent crystals of the drug from developing in your urine. This medication should not be prescribed to patients that have kidney disease. Jennifer has had renal failure. The best antibiotic for Jennifer to be prescribed is the cephalosporin it would cause the least and safest side effects to her.
The process of identifying an unknown bacterial culture has taught me a great deal of knowledge on the different types of bacteria. I learned that bacteria require different types of environments and maintain different oxygen requirements. I inquired a minor obstacle in determining the correct species of my bacteria. I learned that attention to detail is very important in distinguishing bacteria. You must make sure you read the entire test accurately and perform the necessary tests to distinguish bacteria. I realized how important is to determine the appropriate t bacteria it could mean a matter of life and death.