Following Gram staining and microscopic examination, Unknown 15 was identified to be a Gram positive coccoid. Based on these results, all of the Gram negative genera were eliminated including: Enterobacter, Citrobacter, Klebsiella, Escherichia, Pseudomonas, Serratia, Alcaligenes, Neisseria, Proteus, Salmonella, Shigella, Erwinia, Veillonella, and Flavobacterium (5). Bacillus, Lactobacillus, Listeria, Kurthia, and Arthrobacter were eliminated because they did not match the coccoid shape of Unknown 15 (5). The catalase test was the next designated test in the identification of Unknown 15. Unknown 15 tested negative for the enzyme catalase as it did not form gas bubbles after the addition of hydrogen peroxide to the sample. Thus, all catalase
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When aseptically plated on the differential blood agar plate and compared to controls, Unknown 15 was identified as non-hemolytic (gamma hemolysis). Growth best resembled the control Staphylococcus epidermidis which is non-hemolytic, indicating that Unknown 15 did not produce hemolysins to lyse RBCs into hemoglobin (1). Therefore, the alpha and beta hemolytic genus Streptococcus was eliminated (5). There was not an inconsistency in this result but, rather, a variability. The species that Unknown 15 was identified to be, by BLAST sequencing, can either demonstrate alpha or gamma hemolytic activity. If it is examined within 24 hours of plating it will demonstrate alpha-hemolysis, but if examined past 24 hours it will demonstrate gamma-hemolysis (2). Unknown 15 was examined after a one week incubation period, thus, it demonstrated gamma-hemolysis. Mannitol Salt Agar (MSA) was used to distinguish whether Unknown 15 belonged to the genus Enterococcus or Lactococcus. When streak plated onto the MSA medium, Unknown 15 grew on the plate and produced a yellow color change. The growth and color change (indicative of mannitol fermentation) resembled the the positive control Staphylococcus aureus. Very few microorganisms are capable of, both, growing on the halophilic medium and fermenting mannitol; thus, the genus Lactococcus was eliminated …show more content…
The genus Enterococcus was first distinguished in 1899 as a saprophytic coccus that held the capacity to cause infection and originated in the intestine (6). At the same time, researchers, W. MacCallum and T. Hastings defined a similar microbe from a case of endocarditis that would become known as Enterococcus faecalis (6). Enterococcus, a low class of lactic acid bacteria, was categorized as group D streptococci until 1984— it now consists of 37 different species (6, 7). Researchers were able to demonstrate that pre-existing species in genus Streptococcus were genetically closer to species in the genus Enterococcus than Streptococcus (6). In 1984, Streptococcus faecalis was redefined as Enterococcus faecalis (6, 7). The term “faecalis” indicates that the organism is characteristically found in gastrointestinal tracts
When aseptically plated on the differential blood agar plate and compared to controls, Unknown 15 was identified as non-hemolytic (gamma hemolysis). Growth best resembled the control Staphylococcus epidermidis which is non-hemolytic, indicating that Unknown 15 did not produce hemolysins to lyse RBCs into hemoglobin (1). Therefore, the alpha and beta hemolytic genus Streptococcus was eliminated (5). There was not an inconsistency in this result but, rather, a variability. The species that Unknown 15 was identified to be, by BLAST sequencing, can either demonstrate alpha or gamma hemolytic activity. If it is examined within 24 hours of plating it will demonstrate alpha-hemolysis, but if examined past 24 hours it will demonstrate gamma-hemolysis (2). Unknown 15 was examined after a one week incubation period, thus, it demonstrated gamma-hemolysis. Mannitol Salt Agar (MSA) was used to distinguish whether Unknown 15 belonged to the genus Enterococcus or Lactococcus. When streak plated onto the MSA medium, Unknown 15 grew on the plate and produced a yellow color change. The growth and color change (indicative of mannitol fermentation) resembled the the positive control Staphylococcus aureus. Very few microorganisms are capable of, both, growing on the halophilic medium and fermenting mannitol; thus, the genus Lactococcus was eliminated …show more content…
The genus Enterococcus was first distinguished in 1899 as a saprophytic coccus that held the capacity to cause infection and originated in the intestine (6). At the same time, researchers, W. MacCallum and T. Hastings defined a similar microbe from a case of endocarditis that would become known as Enterococcus faecalis (6). Enterococcus, a low class of lactic acid bacteria, was categorized as group D streptococci until 1984— it now consists of 37 different species (6, 7). Researchers were able to demonstrate that pre-existing species in genus Streptococcus were genetically closer to species in the genus Enterococcus than Streptococcus (6). In 1984, Streptococcus faecalis was redefined as Enterococcus faecalis (6, 7). The term “faecalis” indicates that the organism is characteristically found in gastrointestinal tracts