March 21, 2011
A very important step in the identification of an unknown bacterial specimen is determining the cell’s morphology, which can be found via a differential gram stain.
Klebsiella pneumoniae is an opportunistic pathogen that frequently causes nosocomial infections, mainly in immunocompromised patients. K. pneumoniae infections range from mild
urinary tract infections to severe bacteremia and pneumonia with a high rate of mortality and morbidity
Klebsiella is a Gram-negative bacteria that potentially cause nosocomial infections, or infections acquired within a healthcare facility. Such infections include pneumonia, bloodstream infections, wound or surgical site infections, and meningitis (CDC). Following multiple biochemical tests, the unknown bacterium was specifically found to be Klebsiella pneumoniae, a bacteria for which enters the body through the respiratory tract. K. pneumoniae is not spread via air, but rather the contaminated hands of healthcare personnel, or the use of contaminated medical tools, such as ventilators, or intravenous catheters.
Materials and Methods
An unknown culture was obtained from the lab instructor and immediately transferred on to two fresh plates, with one labeled as “working” and the other labeled as “stock.” In order to isolate an individual species and therefore obtain a pure culture, the streak plate method is most commonly used. Approximately every three days, the “working” plate was disposed of, and the “stock” plate became the new “working” plate for the following test.
Before disposing of the original culture, a gram stain was performed as a basis for determining the cell morphology and arrangement. The gram-staining technique distinguishes bacteria as positive or negative, depending upon whether or not the bacteria absorb and retain a crystal violet stain. First, heat fix a bacteria smear from the original culture sample. Once the...