In today's laboratory session we will create an epidemic to show the ease with which microorganisms can be spread by contact, an ever present problem in the clinical area. By the end of this exercise, you should be able to track down the original source of the "infection" using deductive reasoning, an approach similar to that used by public health officials.
From an epidemiological standpoint, two broad etiological principles concerning the spread of infections must be considered: EXPOSURE and SUSCEPTIBILITY. Exposure involves more than contact between the patient and instruments, water, laundry, and waste disposal, etc. The patient's involvement in a variety of diagnostic procedures, requiring movement to other areas of the clinic, further enhances contact with hygienists, technicians, assistants, dentists, and dental students.
Exposure to infection is also increased by the trend toward more complicated dental and surgical diagnostic and therapeutic procedures, such as venipuncture, biopsies, aspirations, extractions, and surgery. Also associated are the use of broad-spectrum antibiotics, corticosteroids, irradiation, and the challenge of the foreign body (sutures and prostheses).
Increased host susceptibility also plays a major role in the promotion of infections, and affected patients comprise three large groups:
Often it is not possible to keep problems that arise in the clinic from spreading to the community. Clinic patients may take home transmissible infections without being apparently ill. Members of the clinic staff may become asymptomatic carriers of microorganisms and infect their patients, families and other people in their communities. (The wearing of surgical gloves by dental professionals protects these clinicians from infection, but puts others at risk from spread of infection, if the gloves are worn outside the work station or cubicle.)
The class will be divided into several groups of students for this experiment. The lab instructor will identify these groups. Each of the groups should have the same results.
One student in each group will unknowingly act as the epidemic initiator. His/her candy is contaminated with Serratia marcescens. The process of shaking hands will simulate the contact that is necessary for an epidemic to spread. In addition, we will assume that all of the "population" is at risk.
At the next lab session, the results will be tabulated and you will be responsible for discovering the initiator of this epidemic.
ONLY THEN, REMOVE THE GLOVES AND DISPOSE OF THEM IN THE LARGE BIOHAZARD BAG. WASH YOUR HANDS WELL.
YOU CANNOT DEPEND UPON DISPOSABLE GLOVES TO KEEP YOUR HANDS FROM BEING CONTAMINATED.
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