Narrowing Causative Agents, Essay Example

A hospital laboratory has been given samples from 25 people who have a suspected food borne illness. The causative agent must be identified. Based on clinical symptoms and patient reports, the doctors have narrowed it down to one of three possible agents; Clostridium, Staphylococcus, or Salmonella. The following are steps taken to identify the causative agent.

To narrow the possibilities of which causative agent it is, technicians use selective media and stain techniques. In order to isolate samples based on growth media, technicians use a 7.5% salt auger to attempt to narrow the genus. Staphylococcus and Clostridium both are able to grow on in a saline rich environment. Upon visual inspection, if the colonies are black, then the genus is Clostridium. If not, it is probably Staphylococcus. They can also be isolated based on staining techniques. If they respond positive to gram testing, they could be either Staphylococcus or Clostridium. Upon visual inspection through a microscope, if they specimen are seen to be rod-shaped, the genus is Staphylococcus. If not, it is Clostridium. By process of elimination, if the bacteria do not grow well in 7.5 % saline environment, do not show a black sheen in colony, are not gram positive, and are not rod-shaped then the genus is probably Salmonella. The practical application of this knowledge is cleanliness in food preparation. Because bacteria are able to grow in so many different mediums, it is important to clean and dry food preparation and serving surfaces thoroughly. To combat different strains, varying or full spectrum disinfectants should be used.

These steps help isolate the genus of the bacteria based on certain features. Based on the process of elimination, the bacteria can be identified. Because doctors had already narrowed the chance of three causative agents; Clostridium, Staphylococcus, or Salmonella, laboratory technicians can find the primary agent with laboratory techniques for eliminating the improbable agents. The use of selective media and staining techniques are simple methods of determining the genus of the culprit agent.

Having returned from a camping trip, a camper has come down with gastrointestinal cramping and diarrhea. Steam water drank is suspected to have been contaminated with a protozoan. Certain protozoans are likely candidates for causing diarrhea, and certain distinguishing features could be used to isolate the causative agent.

For starters, only a few protozoans cause disease. Those are Giardia lamblia, Plasmodium spp. , and Toxoplasma gondii. Toxoplasma gondii is associated with hallucinations and schizophrenia-like symptoms in humans. It is usually contracted from cats. Since those symptoms are not present, it is unlikely it is Toxoplasma gondii. Plasmodium spp. is known to cause malaria, and headache is not one of the symptoms so it is probably not that.  Furthermore, malaria is contracted through mosquitoes. Giardia lamblia is the most likely culprit. It is usually contracted through water and the symptoms are consistent with those reported. It is also known as the traveler’s disease. It is why in some developing countries tourists are warned not to drink the local water. Substandard purification practices often fail to sufficiently cut Giardia lamblia from water sources. As such, many foreigners are susceptible to illness from drinking the water. The case is also similar for water from streams. Fecal content often increases the risk of contamination from Giardia lamblia. The practical application of this knowledge is methods of obtaining clean drinking water from possible contaminated sources. For instance, many people boil water when microbes are suspected. There are also chemical cleaners that can be applied to water that make it drinkable.

Certain protozoans are likely candidates for causing diarrhea, and certain distinguishing features could be used to isolate the causative agent. Steam water drank is suspected to have been contaminated with a protozoan. Having returned from a camping trip, a camper has come down with gastrointestinal cramping and diarrhea. Using the process of elimination, the protozoan is probably Giardia lamblia.