Uknown Microorganism Lab Report
31 October 2011
Identification and observations of Citrobacter Freundii
Introduction
Citrobacter Freundii is a species of bacteria that can be potentially harmful to humans. It is known to cause meningitis by protruding into the brain and replicating itself (1). The Citrobacter species has also been found as a cause of some urinary tract infections, diarrhea, and even gastrointestinal diseases and symptoms (3). C. Freundii can be located in a wide variety of soils and water (3). Lastly, it is also the cause of many nosocomial infections due to its presence in water (1).
Identifying C. Freundii holds importance in order to determine infection in gastrointestinal and urinary tracts and in the brain. These infections will often be noticed through pain in these areas. The main purpose of this laboratory experiment was to utilize microscopic and macroscopic observation, biochemical tests, and antibiotic and disinfectant sensitivity tests to identify an unknown bacterium.
Materials and Methods
Microscopic and Macroscopic Observations All samples and observations of the unknown bacterium were taken after 48 hours of incubation at 35° Celsius. Microscopic observations were performed on four different microscope slides. Three of these observations were gram stains and the last observation was of an endospore staining. The unknown bacteria samples for the endospore stain were taken off of a nutrient agar plate and stained using the Bartholomew and Mittwer’s method. Gram stain samples were taken off of tryptic soy agar and stained using the gram stain procedure that is listed in the Willgoh and Bleakly manual (2).
Physiological Tests All biochemical tests are shown in table 4. Each of these tests required an incubation time of 48 hours at an incubation temperature of 35° Celsius with an exception to the gelatin test that required a 30 minute refrigeration period before observing results. All tests were performed according to the procedures listed in the Willgoh
Identification and observations of Citrobacter Freundii
Introduction
Citrobacter Freundii is a species of bacteria that can be potentially harmful to humans. It is known to cause meningitis by protruding into the brain and replicating itself (1). The Citrobacter species has also been found as a cause of some urinary tract infections, diarrhea, and even gastrointestinal diseases and symptoms (3). C. Freundii can be located in a wide variety of soils and water (3). Lastly, it is also the cause of many nosocomial infections due to its presence in water (1).
Identifying C. Freundii holds importance in order to determine infection in gastrointestinal and urinary tracts and in the brain. These infections will often be noticed through pain in these areas. The main purpose of this laboratory experiment was to utilize microscopic and macroscopic observation, biochemical tests, and antibiotic and disinfectant sensitivity tests to identify an unknown bacterium.
Materials and Methods
Microscopic and Macroscopic Observations All samples and observations of the unknown bacterium were taken after 48 hours of incubation at 35° Celsius. Microscopic observations were performed on four different microscope slides. Three of these observations were gram stains and the last observation was of an endospore staining. The unknown bacteria samples for the endospore stain were taken off of a nutrient agar plate and stained using the Bartholomew and Mittwer’s method. Gram stain samples were taken off of tryptic soy agar and stained using the gram stain procedure that is listed in the Willgoh and Bleakly manual (2).
Physiological Tests All biochemical tests are shown in table 4. Each of these tests required an incubation time of 48 hours at an incubation temperature of 35° Celsius with an exception to the gelatin test that required a 30 minute refrigeration period before observing results. All tests were performed according to the procedures listed in the Willgoh
Cited: 1) Badger, Julie L., Stins, Monique F., Kim, and Kwang Sik. 1999. Citrobacter Freundii Invades and Replicates in Human Brain Microvascular Endothelial Cells. American Society for Microbiology. 67: 4208-4215. 2) Willgohs, J. A. and B. Beakley. 2009. Isolation and identification of an unknown bacterium. In Laboratory manual for general microbiology, 9th edition. Pearson Custom Publishing, New York, NY. 3) Gill, M.A., and Schutze, G.E. 1999. Citrobacter urinary tract infections in children. The Pediatric Infectious Disease Journal. 10: 889-892.