Microbiology: Methods Of Sterilization Quiz Questions!

49 Questions | Total Attempts: 116

SettingsSettingsSettings
Please wait...
Microbiology Quizzes & Trivia

Do you know anything about microbiology methods of sterilization? Sterilization refers to any method that kills life forms, such as microorganisms such as fungi, bacteria, viruses, spores, and unicellular eukaryotic organisms. Sterilization can be accomplished in many ways, including heat, chemicals, contamination, high pressure, and filtration. Upon sterilization, an item is described as being sterile. If you choose to learn more about methods of sterilization in microbiology, try this quiz.


Questions and Answers
  • 1. 
    Microbial contamination is the non-intended or accidental introduction of infectious substances such as bacteria, yeast, fungi, mould, viruses, prions, protozoa and their toxins and also by-products. Contaminated microorganisms come from various sources such as air, water, dust, equipment and also humans. The main products at risk of contamination are topical products (e.g. creams), oral products, multi-dose products (e.g. eye drops), intravenous drugs (IV), contact lenses and also prostheses (e.g. surgical implants). Contamination has a substantial effect on pharmaceutical products used in the treatment and diagnosis of disease, as they contain a wide range of ingredients. They are therefore required to meet good and current pharmaceutical manufacturing standards. For instance, if impurities in form of microbes or chemicals were to be exposed to products during the manufacturing, packaging or storage process, the presence of the contaminants may render it unfit for use or contribute to the quality of the product, as well as reduce the efficacy or the standards that it has to meet. Degradation of active pharmaceutical ingredients (API), may lead to reduced or complete loss of efficacy. Another consequence of contamination would be the alteration of the physical stability of a product, such as the presence of fungal growth, resulting in gritty textures of creams. Micro-organisms release metabolites such as sour fatty acids, and fishy amines, which give a disagreeable taste and smell to products. Therefore, contamination is undesirable. Humans are the biggest sources of microbial contamination, whether in a hospital setting or in a production unit in an industry or clean room setting. For instance, handling products with hands, products can easily get contaminated and develop the Staphylococcus aureus organism. The skin typically shed 5 x 10^8 skin scales per day, in which 90% of the flakes are contaminated with bacteria.  Another way of contamination may arise through natural flora of the human body is through respiratory droplets or saliva, which is easily spread through coughing or sneezing. For instance, the Streptococci species is commonly found in the throat or skin, this can also contribute to contamination. Indigenous opportunistic pathogens such as the Candida or Clostridium species, can greatly affect the shell life stability and safety of products.  In serious cases, contamination of pharmaceutical products may lead to severe illnesses or death of a patient. There are various ways to prevent and control contamination from occurring in the production process of pharmaceutical products. An example would be to practise proper hygiene and sanitation controls in every level of the manufacturing process.  Using strong aseptic techniques in clean room settings, would also reduce the risk of microbial contamination developing in products, or by utilising airlocks or air extraction when required. Transient flora is associated with skin surface, oral cavity and throat etc. It's exposed to multiple environmental assaults (e.g. soaps, detergents & antiseptics). Resident flora of the skin is found in deeper locations, such as sweat glands and pores in the skin, and it's not exposed to fluctuating conditions. It's produced by modulins produced by Staph epidermis, and may play a role in host defences (innate). These type of microbes contribute to contamination through direct contact or through contaminated environmental surfaces.  A study performed by Rahman, 2002 on the microbial contamination of preservative-free eyedrops, concluded that preservatives significantly reduce the likelihood of contamination of eyedrops, and expert intervention reduced contamination. This suggests that preservatives are also good ways to prevent or reduce contamination.  Another study based on the outbreak of neonatal deaths in Brazil associated with intravenous fluids, by Garret DO, et al, 2002, showed that endotoxin-contamination of intravenous liquids lead to neonatal deaths of 36 people. This indicated that sanitation controls in every level of manufacturing processes should be practised, in order to reduce microbial contamination.  Humans as operators contribute to contamination through activity, clothing and behaviours. To monitor contamination levels, contact plates and the finger dabs test can be utilised in order to reduce contamination levels. To control contamination, hygiene and protective clothing should be utilised thoroughly, by hand washing, wearing clean room approved clothing (PPE), having appropriate training to carry out the task, have good general health and by also using good work procedures/practises. 
  • 2. 
    Disinfection is the destruction of microorganisms, it may not kill all microorganisms, but reduce it to a level acceptable for defined purpose. For instance, a level that is deemed as unharmful to health or the quality of products. Disinfectants work by destroying the cell wall of microbes or by interfering with their metabolism. Bacterial endospores are most resistant to disinfectants, although some viruses and bacteria possess some tolerance. They are extensively used in medical and health care, pharmaceutical industry, domestic and institutional areas and also for consumer products. There are many types of disinfectants such as quaternary ammonium compounds (QAC), biguanides and alcohols which are all non-oxidizing agents, they therefore attack all cellular material and prevent the microorganism from functioning. Chlorine, iodine and oxygen releasing compounds, are all known as oxidizing agents. These agents act by oxidizing the cell membrane of micro-organisms, resulting in the loss of structure; leading to cell lysis and potentially death. Disinfectants act on microorganism in two ways, by growth inhibition (bacteriostatic) or by lysis (bactericidal). The lethal effects are the desired outcome, as it suggests that the organism has been destroyed. The 3 main factors that influence antimicrobial effectiveness of disinfectants are: microbial, chemical and physical factors. Microbial factors include intrinsic resistance, acquired resistance and microbial susceptibility. Intrinsic resistance is the chromosomally mediated natural property of the organism. It occurs due to the differences in permeability of the outer cell layers. An example of this is the Pseudomonas aeruginosa bacterium, as it has natural resistance against drugs such as tetracycline, chloramphenicol and sulfonamides. It lacks uptake resulting from the inability of antibodies to achieve effective intracellular concentrations. Such natural insensitivity can be used to innate production of enzymes that inactivate the disinfectant. Acquired resistance results from a genetic change in the micro-organism, which may involve mutation or horizontal gene transfer via transformation, transduction or conjugation. An example of physical factors is temperature, which includes the reaction it has on the disinfectant. The activity of disinfectants increases as the temperature also increases. Temperature is ideally active over a wide range 5 to 55 degrees, it also affects the rate of reaction. Too much increase in temperature causes the disinfectant to degrade and weakens its bactericidal activity, and therefore may produce a potential health hazard. Chemical factors include: concentrations/dilution of disinfectant, pH, water hardness and also time. In terms of concentration, the higher the concentration, the longer it will take to kill microbes. For instance, Quaternary ammonium compounds (QACs) have concentration exponents of 1 and have an increased time factor of 2x when the concentration is ½. An increased pH level improves the antimicrobial activity of some disinfectants e.g. QACs but decreases the antimicrobial activity by altering the disinfectant molecule or the cell surface. Water hardness reduces the rate of kill of certain disinfectants because divalent cations e.g. magnesium and calcium in the hard water, interact with the disinfectant to form insoluble precipitates. Exposure of contact time must be within 5 minutes, and should increase by the use of alternative application methods The disinfectant must bind, traverse microbial cell wall and reach the target site.
  • 3. 
    Which of the following is the best way of controlling contamination in a clean room?
    • A. 

      Hand washing and good working practices

    • B. 

      Hand washing, clean room clothing and clean room behaviour

    • C. 

      Hand washing, clean room clothing, clean room behaviour and good working practices

    • D. 

      Hand washing , clean room clothing and good work practices 

    • E. 

      Hand washing, clean room behaviour and good working practices 

  • 4. 
    Which of the following is most correct regarding alcohol hand rubs?
    • A. 

      Removes dirt, active against all bacteria and active against all spores

    • B. 

      Removes dirt, not active against all bacteria and not active against all spores

    • C. 

      Does not remove dirt, not active against all bacteria and active against all spores

    • D. 

      Does not remove dirt, not active against all bacteria and not active against all spores

    • E. 

      Does not remove dirt, active against all bacteria and not active against all spores

  • 5. 
    Which of the following groups of organisms produce endospores?
    • A. 

      Penicillium and Aspergillus species

    • B. 

      Staphylococcus and Streptococcus species

    • C. 

      Clostridium and Bacillus species

    • D. 

      Gram negative bacteria

    • E. 

      Sporothrix species

  • 6. 
    For an aseptically dispensed product, which of the following are critical control points as defined by HACCP principles
    • A. 

      Hand washing procedures

    • B. 

      Clean room clothing

    • C. 

      Working in appropriate isolators

    • D. 

      Hygienically designed clean room

    • E. 

      All of the above 

  • 7. 
    Which of the following is an eukaryotic micro-organism?
    • A. 

      Burkholderia cepacia

    • B. 

      Candida albicans

    • C. 

      Helicobacter pylori

    • D. 

      Salmonella typhimurium

    • E. 

      Bacteriodes fragilis

  • 8. 
    Which of the following is most correct when referring to types of contamination in a clean room?
    • A. 

      Only one type of contamination: viable (e.g. bacteria, viruses)

    • B. 

      Only one type of contamination: non-viable (e.g. dust, hair)

    • C. 

      Viable (e.g. bacteria, viruses) and non-viable (particulate or chemical)

    • D. 

      Non-viable (particulate not chemical) and viable (bacteria, fungi)

    • E. 

      Viable (viruses, fungi) and non-viable (chemical not particulate)

  • 9. 
    When should the identification of micro-organisms discovered during monitoring be identified:
    • A. 

      In all cases

    • B. 

      Once a week

    • C. 

      When limits are exceeded

    • D. 

      After limits are exceeded on more than one occasion

    • E. 

      Randomly 

  • 10. 
    Members of the human microbiome are a significant problem/concern in contamination control as
    • A. 

      Quality assurance protocols for pharmaceutical products do not always select for these microorganisms.

    • B. 

      Quality assurance protocols for pharmaceutical products take into account the presence of the human microbiome.

    • C. 

      All members of the human microbiome cause disease in humans.

    • D. 

      All members of the human microbiome decrease the stability of the product.

    • E. 

      All of the above 

  • 11. 
    Select the cell envelope component that is a pyrogenic endotoxin
    • A. 

      Lipoprotein 

    • B. 

      Lipolysaccharide

    • C. 

      Phospholipid

    • D. 

      Polysaccharide

    • E. 

      Lipoteichoics

  • 12. 
    Which of the following statements regarding contamination is true?
    • A. 

      A drop of potassium chloride 0.9% is viable, E.coli is viable

    • B. 

      A drop of potassium chloride 0.9% is non-viable, E.coli is non-viable

    • C. 

      A drop of potassium chloride 0.9% is non-viable, E.coli is viable

    • D. 

      A drop of potassium chloride 0.9% is viable, E.coli is non-viable

    • E. 

      None of the above

  • 13. 
    Which of the following groups of organisms produce endospores?
    • A. 

      Penicillium and Aspergillus species

    • B. 

      Staphylococcus and Streptococcus species

    • C. 

      Clostridium and Bacillus species

    • D. 

      Gram negative bacteria

    • E. 

      Sporothrix species

  • 14. 
    Which of the following lists of organisms produce endotoxins/pyrogens?
    • A. 

      S. typhimurium

    • B. 

      E.coli

    • C. 

      P.aeruginosa

    • D. 

      A, B and C

    • E. 

      S.aureus

  • 15. 
    Which of the following areas of the body will possess the highest numbers of microbial cells?
    • A. 

      Hair 

    • B. 

      Intestinal tract 

    • C. 

      Urino-genital tract

    • D. 

      Skin

    • E. 

      Respiratory tract including oro-pharynx

  • 16. 
    The most widely used, effective, economical and reliable method of sterilization used in the health care setting is:
    • A. 

      Ethylene oxide 

    • B. 

      Gas plasma

    • C. 

      Nuclear fusion

    • D. 

      Peracetic acid

    • E. 

      Steam

  • 17. 
    Resident skin bacteria are best described as
    • A. 

      Located deep in epidermis

    • B. 

      Part of innate defence

    • C. 

      Effective removal by antiseptic scrub

    • D. 

      Washing may cause increase in numbers 

    • E. 

      All the above

  • 18. 
    Which of the following is the accepted Sterility Assurance Level (SAL) for pharmaceutical products?
    • A. 

      1 x 106

    • B. 

      1 x 10-6

    • C. 

      6 x 106

    • D. 

      1 x 10-16

    • E. 

      1 x 10-60

  • 19. 
    A pharmaceutical product contains 1 x 1012 cfu/mL, how many decimal reductions are required to reach the accepted SAL?
    • A. 

      18

    • B. 

      180

    • C. 

      0.18

    • D. 

      10

    • E. 

      1.8

  • 20. 
    If a microorganism has a D60 of 0.5 minutes, for how long would you have to heat a suspension the microorganism at 60OC to achieve 8 decimal reductions of the cell population?
    • A. 

      10

    • B. 

      14

    • C. 

      4

    • D. 

      40

    • E. 

      8

  • 21. 
    Which of the following statements about low temperature gas plasma sterilisation is correct?
    • A. 

      Uses fourth state of matter as a sterilising agent

    • B. 

      Generates free radicals from gases

    • C. 

      Plasma glow emits Ultra violet light 

    • D. 

      Used to sterilise surfaces of medical equipment 

    • E. 

      All the above

  • 22. 
    Which of the following describes the Gram positive cell envelope structure?
    • A. 

      Thin layer of peptidoglycan and teichoic acids

    • B. 

      Thin layer of peptidoglycan and lipopolysaccharides

    • C. 

      Thick layer of peptidoglycan, periplasm and lipopolysaccharides

    • D. 

      Thick layer of peptidoglycan and lipoteichoic acids

    • E. 

      Thick lipopolysaccharide layer and thin layer of peptidoglycan

  • 23. 
    Which of the following is a eukaryotic micro-organism?
    • A. 

      Burkholderia cepacia

    • B. 

      Helicobacter pylori

    • C. 

      Candida albicans

    • D. 

      Salmonella typhimurium

    • E. 

      Bacteroides fragilis

  • 24. 
    Which of the following statements is false?
    • A. 

      Endospores are produced in response to unfavourable conditions

    • B. 

      Endospores are survival and dispersal structures produced by Pseudomonas aeruginosa

    • C. 

      Bacillus cereus produces endospores

    • D. 

      Endospores are produced by Clostridium difficile

    • E. 

      Endospores can be inactivated by hypochlorite disinfectants

  • 25. 
    Which of the following organisms is an opportunistic pathogen that has been associated with contaminated eye drops and ointments
    • A. 

      Clostridium species

    • B. 

      Pseudomonas aeruginosa

    • C. 

      Erwinia species

    • D. 

       Salmonella meunchun

    • E. 

      Chromobacter species

Back to Top Back to top