Last updated:
November 12, 2024
- What are the notifiable or critical values in microbiology?
- Refers to certain test results that fall outside of the normal range and may indicate a serious or potentially life- threatening condition. Examples include:
- Positive results for certain pathogens eg. MRSA, Clostridium difficile
- High bacterial counts in blood cultures (indicates sepsis)
- Low WBC counts (sign of severe infection or immunosuppresion)
- Refers to certain test results that fall outside of the normal range and may indicate a serious or potentially life- threatening condition. Examples include:
- Describe the levels of Bioterrorism agents and diseases.
- Category A:
- Can be easily disseminated or transmitted from person to person
- results in high mortality rate
- Have the potential for major public health impact, and therefore might cause panic and social disruption.
- Examples include*: Bacillus anthracis, Clostridium botulinum, Yersinia pesits, Variola major, Francisella tularensis, Ebola, Marbug, Lassa, Machup*
- Category B:
- Moderately easy to disseminate
- Result in moderate morbidity rates and low mortality rates
- Require specific enhancements of CDC’s diagnostic capacity and enhanced disease surveillance
- Examples include: Brucella spp, Clostridium perfringens, Salmonella spp. Eschericia coli, Burholderial mallei, Burkholderia pseudomallei, Chlamydia psittaci, Coxiella burnetii, Ricinus communis, Staph aureus, Rickettsia prowazeki, Vibrio chlerae, cryptosporidium parvum
- Category C:
- Emerging pathogens that could be engineered for mass dissemination in the future
- Ease of production and dissemination
- Have potential for high morbidity and mortality rates and major health impact
- Category A:
- Mention 3 reliable methods of sterilization
- Autoclave: steam sterilization which involves exposing equipment to direct steam at a certain temperature and pressure for a specified period of time.
- Dry air sterilization: exposing equipment to dry heat, which gets absorbed by the external layer and is transferred to the internal layers by conduction.
- Ethylene oxide gas sterilization: includes preconditioning and humidification, gas introduction, exposure, evacuation and air washes.
- Hydrogen peroxide gas plasma sterilization: Hydrogen peroxide diffusion and gas plasma generation→ formation of free radicals→ damage enzymes, nucleic acid and disrupt cellular metabolisms of pathogenetic organisms
- Pasteurization: pathogen destruction through brief heating, especially of milk and other protein- containing products.
- Mention 5 groups of disinfectants
- Alcohol- based disinfectants eg. isopropyl alcohol and ethyl alcohol
- Bisbiguanides eg. chlorhexidine
- Phenol eg. orthophenylphenol and ortho-benzyl-para-chlorophenol
- Halogen-releasing agents
- Iodine and iodophors eg. povidone-iodine and poloxamer-iodine
- Chlorine-releasing agents eg. Sodium hypochlorite and Chlorine dioxide
- Hydrogen peroxide
- Aldehydes eg. glutaraldehyde
- Quaternary ammonium compounds eg. Benzalkonium chloride
- List the various microscopy modalities available to the microbiologist in the study of microorganisms
- Light microscopy
- Dark-field microscopy
- Fluorescence microscopy
- Micrometry (measurement)
- How is sterilization controlled?
- Using temperature, pressure, and time indicators: These indicators help to ensure that the sterilization process has been carried out under the correct conditions for the required amount of time.
- Using biological indicators: These are biological substances that are designed to be sensitive to the sterilization process. They can be used to confirm that the sterilization process has been effective.
- Using chemical indicators: These are chemicals that change color or some other physical property when exposed to the sterilization process, indicating that the process has been successful.
- Using physical indicators: These are devices that are placed in the sterilization chamber to ensure that the correct conditions are being maintained.
- Using process challenge devices: These are devices that are designed to simulate the resistance of microorganisms to the sterilization process, and are used to confirm that the sterilization process is effective.
- Using process control charts: These are graphical representations of the sterilization process that are used to monitor and control the process
- Briefly describe Spaulding’s classification of devices’ risk of infection.
- Critical: contact sterile intermediate (High risk)
- Semicritical: contact mucous membrane or non-intact skin (High to intermediate risk)
- Non-critical: contact skin (low risk)
- Briefly describe the levels of disinfection.
- High level disinfection (HLD): Chemical sterilants, Heat (pastuerization)
- Intermediate-level disinfection (ILD): Chlorine based products, phenolics – EPA measured with tuberculoid activity
- Low-level disinfection (LLD): Chemicals – EPA measured with tuberculoid activity
- What are the temperatures and durations employed in sterilization?
- Autoclave: 121*C for 15 minutes
- Flash sterilization: 131*C for 3 – 10 minutes (emergencies)
- Dry heat: 150C for 150 minutes or 160C for 120 minutes or 170*C for 60 minutes
- Describe the order of resistance of microorganisms to sterilization and disinfection.
- Spores are the most resistant to sterilization and disinfection methods. They can survive high temperatures, pressure, radiation, and chemicals.
- Bacteria and viruses are less resistant than spores, but can still survive some sterilization and disinfection methods.
- Fungi and algae are less resistant than bacteria and viruses.
- Protozoa and helminths are the least resistant to sterilization and disinfection methods
- What are the sections of a Central Sterile Supply Department (CSSD)?
- Receiving area
- Dirty area for cleaning
- Inspection, Assembly, and packaging area
- Decontamination and Sterilization (FIFO)
- Clean area for storage of sterilized packs
- Dispatch