After performing my keyed out tests, I found that the bacteria I had was Enterobacter aerogenes. I used the catalase test and the indole test, of which both confirmed the identity of my bacteria. The first test I performed on my culture was the gram stain to see if the bacteria was positive or negative, along with this, I looked at the shape of the bacteria. Both of these led me to know that it was a gram negative bacilli. Therefore, I followed my key and performed the phenol red lactose test. This gave me a positive yellow with a bubble reading. I then moved to my citrate test. This test was a positive blue reading and therefore, I knew that I had Enterobacter aerogenes. The two tests for additional confirmation, the indole test and the catalase test, drew the same conclusions. The indole test showed me that my unknown did not produce indole and that the bacterium did not contain the enzyme tryptophanase, therefore; Kovac’s Reagent did not react, showing a negative indole test. This test gave me the confirmed E. aerogenes. I also did the catalase test for confirmation. This test tests for the presence of the enzyme catalase, which breaks down hydrogen peroxide. The result of this test showed bubbling which also confirmed my bacteria to be Enterobacter aerogenes. I did a third test just to double check both of my tests, and that was the Voges Proskauer test. This gave me the desired positive result as well (Department of Biology, 2018).
Enterobacter aerogenes is a gram negative bacilli bacterium that does not form spores. It is nosocomial and a pathogenic bacterium that causes opportunistic infections. It is also a facultative anaerobe. This bacterium gets its name from its predominant natural habitat in the intestines of animals, which in Greek is “enteron” meaning “intestine” (Encyclopedia Britannica, 2018). It also lacks urease activity, which differs from the other members of the species (Davin-Regli, A., & Pagés, J., 1970, January 1). These bacterial colonies are capable of colonizing several environments and hosts, and thereby, rapidly and effectively, change their metabolism makeup to handle the outside world's stresses and conditions, making this extremely versatile and virulent, ultimately reading it for any sort of treatment the patient pursues. Enterobacter aerogenes also contains eighty-seven tRNA and eight rRNA operons, which aid in the ability of it to translate imported genes that have different codons. This improves the bacteria’s ability to integrate foreign genes (Davin-Regli, A., & Pagés, J., 1970, January 1).
E. aerogenes is generally found in the human gastrointestinal tract, and it does not normally cause any disease in healthy individuals. It has been found to live in various wastes, hygienic chemicals, soil, and plants (Antimicrobialcopper.org, 2018). It is known to be found ubiquitously in nature. However, this organism is most often seen when a patient has been in hospitals, nursing homes, college dorms, or other close proximity spaces (Encyclopedia Britannica, 2018). This bacteria has also been seen to be surviving on stainless steel in healthcare settings causing serious damage (Antimicrobialcopper.org, 2018). This bacteria has also emerged greatly in patients that are nosocomial in the intensive care unit or on mechanical ventilation (Davin-Regli, A., & Pagés, J., 1970, January 1).
Enterobacter aerogenes possess flagella and are motile. This increases the bacterium's ability to synthesize an enzyme known as ornithine decarboxylase, which is used often to distinguish this bacterium from others (Encyclopedia Britannica, 2018). They are also able to make numerous genetic mobile elements that help with strong antibiotic resistance (Davin-Regli, A., & Pagés, J., 1970, January 1). This bacteria can cause a variety of conditions and disease such as eye and skin infections, bacteremia, meningitis, septic shock syndrome, urinary tract infections, and pneumonia (Antimicrobialcopper.org, 2018). Most commonly, infections with this bacteria do not have any specific clinical presentation of symptoms or signs that would differentiate it from other bacterial infections. However, it is sometimes classified based on the type of diarrhea produced. Patients may also present with dehydration, vomiting for more than three days, high grade fever that can not be controlled with acetaminophen and/or that lasts longer than three days, presence of blood in stool, and a hard, or swollen belly (Healthofchildren.com, 2018).
Treatment for these infections or diseases typically includes antimicrobial therapy such as an aminoglycoside, fluoroquinolone, cephalosporin, or imipenem. However, in uncomplicated cases, symptoms usually go away within five to ten days without treatment of antibiotics. Of course, there are other cases when antibiotics are necessary to overcome the infection (Healthofchildren.com, 2018). These bacteria are special because they are capable of making an enzyme which will cut the structural ring of the beta-lactam antibiotic. This will increase the chance of drug resistance as seen by the ciprofloxacin-resistant and multidrug-resistant E. aerogenes. Gentamicin, tobramycin, and amikacin are the normal antibiotics used. Most recently, approaches with combination therapy, including multiple antibiotics with different core structural antimicrobials, have seen to be increasingly effective (Encyclopedia Britannica, 2018).
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