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Parasites in patients

Please refer to the attached case study.

1. Why might the physician suspect that parasites could be a possibility in these patients?
2. What parasites might the physician have suspected?
3. How should stool culture for routine bacterial pathogens be processed? Be sure to include appropriate media and atmosphere of incubation.
4. What bacterial pathogens should be included in the screening of a routine stool culture, and how would the clinical laboratory scientist processing the culture recognize these potential pathogens?
5. When a stool specimen is bloody, additional testing is often recommended or suggested to the physician (especially with children or the elderly). What pathogen is of concern in that situation, and how is this specimen processed?
6. Other more unusual bacterial pathogens may also cause diarrheal disease, and physicians may request additional testing for these organisms. What organisms might be suspected, and what media and atmosphere of incubation are used to isolate these organisms?
7. Based on the history and laboratory results presented, what is the most probable cause for the diarrheal disease in these patients?

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1. Why might the physician suspect that parasites could be a possibility in these patients?
The physician suspected parasites based on the patients history and physical findings, including their recent camping trip, and diarrhea accompanied by headache, myalgia and malaise which can all be indicative of parasitic infection. Additionally the rain may have led to physician to believe that their water or food may have become contaminated by a parasite which they subsequently swallowed and became infected.

2. What parasites might the physician have suspect?
Giardia lamblia, people become infected with Giardia by swallowing Giardia cysts found in contaminated food or water. Giardia infection rates have been known to go up in the summer and backpackers or campers who drink untreated water from lakes or rivers are especially susceptible to Giardia infection.

Cryptosporidium parvum is a significant cause of waterborne and foodborne illness worldwide. This parasite can be found in soil, food, water or surfaces that have been contaminated with feces from infected humans or animals. Consuming food or water contaminated with C. parvum oocysts leads to infection. Symptoms appear 2 to 10 days after ingestion of C. parvum oocysts and hikers, campers, or any other persons who may drink from untreated water supplies are susceptible to infection.

3. How should a stool culture for routine bacterial pathogens be processed?
Most laboratories will routinely setup a BAP, MAC, HE (or XLD), CIN and Campy-BAP. A swab is used to inoculate plates and obtain representative areas of the specimen
- Sample areas that are purulent or bloody
- Make primary streak with swab
- Streak for isolation using sterile loop
- Non inhibitory media (BAP) should always be inoculated first

MacConkey Agar (MAC)
• Selective, differential
- Selects for Enterobacteriacea and other GNR's
- Differentiates between lactose and non-lactose fermenters
• Lactose sole ...

Solution Summary

Parasites in patients are examined.

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