4 A particular disinfectant takes 2 min of contact time to k

4. A particular disinfectant takes 2 min. of contact time to kill 90% of all microorganisms on a particular surface. How would the following situations affect the time normally needed to kill 90% of all microorganisms? (1.5 pts.)

   a. Microorganisms are in a dirt matrix (i.e. someone falls outside and scraps their knee).

   b. Microorganisms are in a working refrigerator (a culture of Salmonella is spilled in a refrigerator).

   c. The surface was swabbed down with ethanol 2 hours previously.

5. Entamoeba histolytica and Giardia lamblia were isolated from the stool sample of a 45 year old man, andShigella sonnei was isolated from the stool sample of an 18 year old woman. Both patients experienced diarrhea and severe abdominal cramps, and prior to onset of digestive symptoms, both had been treated by the same chiropractor. The chiropractor had administered colonic irrigations (enemas) to these patients. The device used for this treatment was a gravity-dependent apparatus using 12 liters of tap water. There were no check valves to prevent backflow, so all parts of the apparatus could have become contaminated with feces during each colonic treatment. The chiropractor provided colonic treatment to four or five patients per day. Between patients, the adaptor piece that is inserted into the rectum was placed in a “hot-water sterilizer.” Tap water does not contain pathogens. (2 pt.)

What 2 errors were made by the chiropractor?

Solution

Question 4)

a) The number of microbes present on the dirt matrix is more. The more microbes to kill, the longer it takes to eliminate the entire population.

b) Some microbe can grow at lower temperatures. Therefore the activity of most disinfectants decreases as the temperature decreases. It will take longer time to kill the microbes in refrigerator.

c) Ethanol effectively kill microbes. Prior swabbing of ethanol increases the activity of disinfectants. Therefore fastly kill the microorganism.

Question 5: The 2 errors made by the chiropractor were

1) There were no check valves to prevent backflow because the device used for this treatment was a gravity-dependent apparatus using 12 liters of tap water. So all parts of the apparatus could have become contaminated with feces during each colonic treatment.

2) Same chiropractor is using for the colonic treatment of four or five patients per day. Therefore spreading of pathogen from one patient to another.