What Are Porter Examinations?
Carrier screening tests are laboratory examinations conducted to determine whether individuals working in food-related jobs are carriers of diseases that can be transmitted through food. A carrier screening is not a single test, but rather a collection of various microbiological tests. To be cleared as a non-carrier, all included tests must yield negative results.
Which Tests Are Included in Porter Examinations?
Carrier screening for individuals working in the food industry or sanitary establishments typically includes the following:
- Stool Culture:
Performed at least once a year to detect Salmonella and Shigella bacteria. - Microscopic Stool Examination:
Performed at least every six months to detect Entamoeba histolytica cysts, Giardia lamblia cysts, and helminth (parasitic worm) eggs. - Throat and Nasal Swab Cultures:
Performed at least once a year to screen for Staphylococcus aureus. - Chest X-ray:
Conducted at least once a year to check for tuberculosis. - Hepatitis B Testing:
Also recommended for those working in the food industry.
Who Should Undergo Porter Examinations?
Carrier screening is especially important for the following groups:
- Food industry workers
- Employees of sanitary establishments (e.g., kitchens, bakeries, food storage)
- Cleaning sector personnel
- Employees working in preschools and kindergartens
What Precautions Should Workplaces Take Regarding Infectious Diseases?
In workplaces, carrier screening should be implemented:
- As part of the pre-employment medical examination for new hires
- As periodic health checks for current employees
Based on test results, an effective surveillance system should be established to detect and monitor infectious disease carriers. In the event that an employee is found to be carrying an infectious pathogen, appropriate precautions should be taken. This may include temporary removal from work or reassignment to a non-risk position, to prevent the spread of infection.
How Are Porter Examinations Conducted?
Stool Culture
A stool culture identifies and isolates bacteria in the lower gastrointestinal tract, distinguishing between pathogenic and normal flora. It helps determine if bacteria are the cause of gastrointestinal symptoms (gastroenteritis).
A clean stool sample is collected in a sterile container, ensuring it is not contaminated by urine or water. The sample must be delivered to the lab within two hours or transferred to a transport medium for preservation. In infants, stool samples may be collected using a rectal swab.
Throat Culture
This test identifies infections in the throat and tonsils. A sterile cotton swab is used to collect a sample from the tonsils and pharynx. The sample is incubated for 18–24 hours to detect the presence of beta-hemolytic bacteria.
Nasal Culture
Nasal cultures are used to identify potentially harmful microorganisms present in the nasal cavity. A swab is taken from inside the nostrils and cultured to check for bacterial growth.
Microscopic Stool Examination
This test detects parasitic organisms such as protozoa and helminths. It is also useful for identifying fecal leukocytes and other cells, such as red blood cells or yeast, under the microscope.