Microbiology Lab Report

Topics: Escherichia coli, Enterobacteriaceae, Growth medium Pages: 4 (767 words) Published: February 7, 2014

Identifying an unknown bacteria can be an arduous journey. The journey starts

out by performing a gram stain and then performing various tests. The first part should not be challenging. The challenging part is analyzing your results and using the data to infer what your unknown organism might be.


When I was first handed my organism, I performed a rather unconventional test: I

smelled it. Throughout the semester of dealing with various organisms, I had learned that there are certain bacteria that smell much worse than others. These bacteria are the Enteric bacteria. Escherichia coli and Proteus hauseri were definitely two of the smelliest ones that I encountered. So I took opened my culture and I waffed. It was definitely an Enteric bacteria, though it did not smell as bed as bad as Escherichia coli and Proteus hauseri.


Now smelling is a very inconclusive tests, so I performed various tests to confirm

my suspicion. In the end, all of the tests performed confirmed that my unknown was indeed an Enteric bacteria. It was Klebsiella pneumoniae. K.pneumoniae occasionally causes pneumonia in humans (Madigan et al. 2009, pg. 423).

K.pneumoniae is found in the nasiopharynx and in the intestinal tract (Podschun & Ullmann, 1998).

In recent years, K.pneumoniae has been developing resistance to various

antibiotics. One important class of antibiotics are carbapenems, which are usually the last line of defense for treatment again a K.pneumoniae infection (Bratu 2005).

Experimental Procedure
- Gram stain
Inoculated unknown in the following agar plates:
- Phenylethyl Alcohol Agar
- Mannitol Salt Agar
- MacConkey Agar
- Eosin Methylene Blue agar
- Hektoen Enteric Agar
- Milk agar
- Starch agar
- Nutrient agar
Inoculate in the following tubes:
- Nutrient agar slant
- Simmons citrate agar slant
- Nutrient gelatin stab tube
- SIM tube
- Phenol Red Glucose, lactose, and sucrose tubes
The gelatin stab tubes were put at...

References: Madigan, M., Martinko, J., Dunlap, P., & Clark, D. (2009). Brock Biology of
Microorganisms. 12 ed. Pearson Education.
Podschun, R., & Ullmann, U. (1998). Klebsiella spp. as nosocomial pathogens:
Epidemiology, taxonomy, typing methods, and pathogenicity factors. Clinical
Microbiology Reviews, 11(4), 589-603.
Bratu, S., Landman , D., Haag, R., Recco, R., Eramo, A., Alam, M., & Quale, J. (2005). Rapid
spread of carbapenem-resistant klebsiella pneumoniae in new york city: a new threat to
our antibiotic armamentarium. Arch Intern Med, 165(12), 1430-5.
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