Microbiology In Nursing MCQ Quiz - Objective Question with Answer for Microbiology In Nursing - Download Free PDF

• Viruses are microorganisms that rely on specific transmission routes to spread from one host to another. These routes are often related to the virus's characteristics, replication cycle, and the tissues they infect. Understanding the transmission routes is essential for preventing the spread of infectious diseases.
• The correct matching is as follows:
  • Hepatitis A → Fecal-oral (1-a): Hepatitis A is primarily transmitted through the ingestion of contaminated food or water. It is linked to poor sanitation and hygiene practices.
  • Hepatitis B → Blood and body fluids (2-b): Hepatitis B is spread through direct contact with infected blood, semen, or other bodily fluids, often through unprotected sexual contact, shared needles, or from mother to child during childbirth.
  • HIV → Sexual, blood-borne (3-c): HIV is transmitted through unprotected sexual contact, sharing of needles, transfusion of infected blood, and from mother to child during pregnancy, childbirth, or breastfeeding.
  • Rabies → Animal bite (4-d): Rabies is transmitted through the bite or scratch of an infected animal, as the virus is present in the saliva of the infected animal.

• This option incorrectly matches Hepatitis A to blood and body fluids, which is not accurate since Hepatitis A is transmitted via the fecal-oral route. Similarly, HIV is incorrectly matched to the fecal-oral route, which does not align with its transmission pathways.

• This option contains multiple incorrect matches. For instance, Hepatitis A is incorrectly linked to sexual transmission, and Rabies is incorrectly linked to blood and body fluids. These errors demonstrate a misunderstanding of the transmission mechanisms for these viruses.

• This option incorrectly matches Hepatitis A with animal bites and Rabies with the fecal-oral route. These mismatches disregard the actual biological transmission routes of the respective viruses.

• The correct matching of viruses to their transmission routes is crucial for implementing effective public health measures to control and prevent the spread of diseases. Among the given options, the correct answer accurately aligns the viruses with their primary modes of transmission.

• Hepatitis B can be transmitted sexually. This is a true statement as Hepatitis B virus (HBV) can be spread through sexual contact with an infected individual. HBV is present in bodily fluids such as blood, semen, and vaginal secretions, making sexual transmission one of the primary modes of infection.
• Complement fixation test is used to detect antigen-antibody reactions. This is also correct. The complement fixation test is an immunological assay used to determine the presence of specific antigens or antibodies in a sample by observing the fixation or consumption of complement proteins during antigen-antibody reactions.

• Rationale: This statement is incorrect. ELISA (Enzyme-Linked Immunosorbent Assay) is not solely a qualitative test. It is both qualitative and quantitative, depending on the specific assay design. ELISA is widely used for detecting and measuring antigens, antibodies, proteins, and other substances in a sample. The quantitative aspect involves generating a standard curve to calculate the concentration of the detected substance.

• Rationale: This statement is incorrect. Immunofluorescence does not involve radioactive labels; it relies on fluorescent dyes or tags to visualize antigen-antibody interactions under a fluorescence microscope. These fluorescent markers emit light when excited by specific wavelengths, enabling visualization of the targeted proteins or structures.

• Rationale: This statement is incorrect because Statements 1 and 4 are false, as explained above. Therefore, not all statements can be considered correct.

• The correct statements are 2 and 3. Hepatitis B can be transmitted sexually, and the complement fixation test is used to detect antigen-antibody reactions. ELISA is both qualitative and quantitative, and immunofluorescence involves fluorescent labels, not radioactive ones.

• The second statement, "PCR can be used to detect viral RNA," is true. Polymerase Chain Reaction (PCR) is a molecular biology technique used to amplify and detect specific DNA or RNA sequences. In the case of viral RNA, reverse transcription is performed to convert RNA into complementary DNA (cDNA), which is then amplified and detected using PCR.
• The fourth statement, "Hypersensitivity reactions can be immediate or delayed," is also correct. Hypersensitivity reactions are immune responses that cause tissue damage. They are classified into four types (Type I-IV), with Type I (e.g., allergies) being immediate and Types II-IV (e.g., autoimmune diseases or contact dermatitis) being delayed.

• Rationale: This statement is incorrect. Radioimmunoassay (RIA) uses radioactive isotopes, not enzymes, for detection. It is a sensitive technique used for measuring antigens or antibodies by using radiolabeled substances.

• Rationale: This statement is also incorrect. Enzyme-Linked Immunosorbent Assay (ELISA) detects antigens or antibodies by producing a color change through enzyme-substrate reactions. Agglutination, on the other hand, refers to the clumping of particles, which is not a feature of ELISA but is observed in techniques like hemagglutination assays.

• PCR is widely used in clinical diagnostics for detecting pathogens, including viruses like HIV, Hepatitis C, and SARS-CoV-2. It is highly sensitive and specific, making it a gold standard in molecular diagnostics.
• Hypersensitivity reactions are an important component of immunology. Immediate reactions involve rapid immune responses, often mediated by IgE antibodies, while delayed reactions are mediated by T cells and occur over hours or days.
• RIA, while once widely used, is now less common due to the use of safer, non-radioactive methods like ELISA.

• The correct statements are 2 and 4. PCR is a powerful tool for detecting viral RNA, and hypersensitivity reactions can indeed be categorized as immediate or delayed based on their mechanisms and timing.

• Hypersensitivity is an exaggerated or inappropriate immune response to an antigen that leads to tissue damage or other pathological consequences. There are four types of hypersensitivity reactions, classified as Type I, II, III, and IV, based on their underlying immune mechanisms.
• The correct matches are:
  • Type I - Anaphylaxis: Type I hypersensitivity involves an immediate allergic reaction mediated by IgE antibodies. Upon exposure to an allergen, IgE binds to mast cells and basophils, triggering the release of histamine and other inflammatory mediators, causing symptoms such as swelling, hives, respiratory distress, and potentially life-threatening anaphylaxis.
  • Type II - Hemolytic anemia: Type II hypersensitivity is mediated by IgG or IgM antibodies targeting antigens on the surface of cells. This leads to cell destruction via complement activation or antibody-dependent cellular cytotoxicity (ADCC). Hemolytic anemia, where red blood cells are destroyed due to autoimmune attack or drug-induced reactions, exemplifies this type.
  • Type III - Systemic Lupus Erythematosus (SLE): Type III hypersensitivity occurs when immune complexes (antigen-antibody complexes) are deposited in tissues, leading to inflammation and tissue damage. SLE is a classic example, where immune complexes accumulate in organs like the kidneys, joints, and skin, causing systemic autoimmune symptoms.
  • Type IV - Tuberculosis (TB) skin test: Type IV hypersensitivity is a delayed-type reaction mediated by T cells rather than antibodies. It typically occurs 24–72 hours after exposure to an antigen. The TB skin test is a diagnostic example, where T cells respond to Mycobacterium tuberculosis antigens injected into the skin, leading to localized swelling and redness.

• Understanding the mechanisms and examples of hypersensitivity types is essential for diagnosing and managing allergic and autoimmune conditions. The correct matches (1-a, 2-b, 3-c, 4-d) align with the immunological basis of each hypersensitivity type, ensuring accurate classification and clinical relevance.

• Serological techniques are laboratory methods used to detect and measure specific antigens or antibodies in a sample. Each technique has a unique underlying principle that guides its application and interpretation.
• The correct matching of techniques with their principles is:
  • 1. ELISA (Enzyme-Linked Immunosorbent Assay) - Principle: Enzyme-linked color change. ELISA uses enzymes linked to antibodies or antigens to produce a measurable color change when a substrate reacts with the enzyme. This technique is highly sensitive and is used for detecting specific proteins or antibodies in a sample.
  • 2. Agglutination - Principle: Visible clumping of particles. Agglutination occurs when antibodies bind to antigens on the surface of particles such as cells or beads, causing them to clump together visibly. This is commonly used for blood typing and rapid diagnostic tests.
  • 3. Precipitation - Principle: Formation of lattice in solution. Precipitation involves the formation of antigen-antibody complexes that aggregate into a visible lattice structure in a solution. This technique is often used for detecting soluble antigens.
  • 4. PCR (Polymerase Chain Reaction) - Principle: Amplification of DNA/RNA. PCR is a molecular technique used to amplify specific DNA or RNA sequences, enabling their detection even in extremely small quantities. It is widely employed in genetic testing and infectious disease diagnosis.

• Rationale: This option incorrectly matches ELISA with visible clumping of particles (b), which is actually the principle of agglutination. Similarly, it mismatches PCR with lattice formation in solution (c), which is the principle of precipitation. These errors make this option incorrect.

• Rationale: This option mismatches ELISA with amplification of DNA/RNA (d), which is the principle of PCR. It also incorrectly pairs agglutination with lattice formation in solution (c), which is the principle of precipitation. These mismatches render this option incorrect.

• Rationale: This option incorrectly matches ELISA with lattice formation in solution (c), which is the principle of precipitation. Additionally, it mismatches PCR with visible clumping of particles (b), which is the principle of agglutination. These inaccuracies make this option incorrect.

• The correct matching of serological techniques with their principles is 1-a, 2-b, 3-c, 4-d. Understanding the principles behind these techniques is crucial for selecting the appropriate method for specific diagnostic and research applications.

Diphtheria is a common infectious disease in India. Diphtheria is an acute communicable disease that affects the nose, throat, and tonsils. The bacilli multiply at the site of implantation (insertion into the body), be it the throat, nose, or tonsils. It produces local lesions at the site of implantation. This lesion is characterized by the formation of a patch or patches of greyish false-membrane on the affected parts such as the tonsils or larynx (voice box). It also produces an offensive and strong odor.

Important Points

Diphtheria Vaccination (Prevention and Management)

• The only effective way of preventing the disease is by active immunization by diphtheria toxoid to the general population.
• It is given as DPT or triple antigen along with immunization for whooping cough and tetanus.
• A booster is given one year after the third injection is given. For children over the age of six years, only DT containing diphtheria and tetanus toxoids is given.
• There is a test to find out individuals who are susceptible to diphtheria. This test is known as the Schick test. This test can also be used for confirmation of successful immunization.
• Penicillin and Erythromycin are effective but should be given along with the antitoxin. 
• Transmission of diphtheria is through droplet infection or infected dust. of the cervical lymph glands. 
• Immunization is the most effective way of preventing the disease.

• The Dick test is specifically designed to determine an individual's susceptibility to scarlet fever, which is caused by group A Streptococcus bacteria producing erythrogenic toxin.
• In the Dick test, a small amount of diluted erythrogenic toxin is injected into the skin. If the person is susceptible (meaning they lack immunity), a red, inflamed area will develop at the injection site within 24 hours. If the person is immune, no significant reaction occurs.

• Rationale: The Schick test is used to determine susceptibility to diphtheria by injecting a small amount of diphtheria toxin into the skin. It is not related to scarlet fever.

• Rationale: The Mantoux test (or tuberculin skin test) is used to detect latent tuberculosis infection by injecting purified protein derivative (PPD) under the skin. It is not related to scarlet fever.

• Rationale: The Widal test is a serological test used to diagnose enteric fever (typhoid and paratyphoid fever) by detecting antibodies against Salmonella bacteria in the blood. It is not related to scarlet fever.

• Among the given options, the Dick Test is the correct test used to determine susceptibility to scarlet fever.

• Artificially acquired active immunity refers to the immunity that is developed when a person is exposed to a vaccine containing a weakened or dead pathogen, or parts of the pathogen. This exposure stimulates the immune system to produce a response, including the creation of memory cells, which can quickly respond to future exposures to the pathogen.
• Vaccines work by mimicking the infection, causing the immune system to develop a defense (antibodies) against the pathogen without causing the disease itself. This is why vaccinated individuals can later fight off the actual pathogen more effectively if they are exposed.

• Rationale: This type of immunity is acquired by the transfer of antibodies or activated T-cells from an immune individual to a non-immune individual. This can happen through treatments like immunoglobulin therapy. It provides immediate but short-term protection because the body does not produce its own antibodies or memory cells.

• Rationale: This type of immunity occurs when a person is exposed to a live pathogen, contracts the disease, and then recovers. During the infection, the body produces a primary immune response, including the development of memory cells, leading to long-lasting protection against future infections by the same pathogen.

• Rationale: This type of immunity is provided through natural means such as the transfer of maternal antibodies to the fetus through the placenta or to the infant through breast milk. This type of immunity provides immediate but temporary protection as the transferred antibodies eventually degrade and are not replaced.

• Artificially acquired active immunity is the correct answer as it involves the immune system actively responding to a vaccine to develop long-term protection. This is different from passive immunity (both natural and artificial), where antibodies are provided directly, and natural active immunity, which involves actual infection and recovery.

• Vitamin K is also known as the anti-haemorrhagic vitamin. This is because it plays a crucial role in the coagulation (clotting) process of the blood, which is essential to prevent excessive bleeding.
• There are several types of vitamin K, including K1 (found in green leafy vegetables) and K2 (produced by bacteria in the human gut). Both types are vital for synthesizing proteins that control bleeding.

• **Function in Blood Clotting**: Vitamin K is essential for the synthesis of prothrombin and other clotting factors, which are proteins that help blood to clot.
• **Sources**: Vitamin K1 is found in green leafy vegetables such as kale, spinach, and broccoli. Vitamin K2 is found in fermented foods and is also produced by gut bacteria.
• **Deficiency**: A deficiency in Vitamin K can lead to excessive bleeding and bruising because the blood takes longer to clot. This condition is known as vitamin K deficiency bleeding (VKDB) or simply hemorrhagic disease.
• **Medical Use**: Vitamin K is used to treat and prevent VKDB, particularly in newborns who are given a vitamin K injection at birth to prevent bleeding disorders.

• Rationale: Vitamin D is primarily involved in the regulation of calcium and phosphate metabolism, promoting bone and tooth health. It does not play a direct role in blood clotting or preventing hemorrhage.

• Rationale: Vitamin A is important for vision, immune function, and skin health. It is not involved in the coagulation process or in preventing bleeding.

• Rationale: Vitamin B12 is crucial for nerve function and the production of DNA and red blood cells. It does not have a role in blood clotting or in preventing hemorrhage.

• **Interactions**: The effectiveness of Vitamin K can be reduced by certain medications such as warfarin, a common anticoagulant used to prevent blood clots.
• **Storage**: Vitamin K is fat-soluble, meaning it is stored in the body's fatty tissue and liver. Thus, a well-balanced diet typically provides sufficient levels.
• **Supplementation**: Besides dietary sources, vitamin K supplements are available and can be necessary for individuals with certain health conditions that impair absorption or increase the risk of bleeding.

• Vitamin K is specifically known as the anti-haemorrhagic vitamin due to its critical role in the blood clotting process. This distinguishes it from the other vitamins listed, which have different primary roles in the body.

• The Mantoux test, or tuberculin skin test, is based on a Type IV hypersensitivity reaction, also known as delayed-type hypersensitivity.
• Type IV hypersensitivity involves T-cell mediated immune responses rather than antibody responses. When an individual who has been previously sensitized to Mycobacterium tuberculosis (the bacteria that cause tuberculosis) is exposed to tuberculin purified protein derivative (PPD) injected into the skin, memory T cells recognize the antigen and initiate an inflammatory response.
• This response results in induration (hardening) and erythema (redness) at the site of injection within 48 to 72 hours if the person has been exposed to the tuberculosis bacteria.

• Rationale: Type I hypersensitivity reactions are mediated by IgE antibodies and mast cells, leading to rapid allergic reactions such as anaphylaxis, hay fever, and asthma. These reactions occur within minutes of exposure to the allergen and are not involved in the Mantoux test.

• Rationale: Type II hypersensitivity reactions involve IgG or IgM antibodies targeting antigens on the surface of cells, leading to cell destruction. Examples include hemolytic anemia and transfusion reactions. This mechanism is not related to the Mantoux test.

• Rationale: Type III hypersensitivity reactions occur when immune complexes (antigen-antibody complexes) form and deposit in tissues, causing inflammation and tissue damage. Examples include systemic lupus erythematosus and rheumatoid arthritis. This mechanism is also not related to the Mantoux test.

• The Mantoux test relies on a Type IV hypersensitivity reaction, characterized by a delayed response mediated by T cells. Understanding the specific immune mechanisms involved in different hypersensitivity reactions helps in accurately interpreting diagnostic tests and managing immune-mediated conditions.

• Opsonization is a process where pathogens are marked for ingestion and destruction by phagocytes. It involves the binding of opsonins, such as antibodies or complement proteins, to the surface of a pathogen.
• This binding enhances the ability of phagocytes, like macrophages and neutrophils, to recognize and engulf the pathogen, thus facilitating its elimination from the body.
• Opsonins act as a bridge between the pathogen and the phagocyte, increasing the efficiency of the phagocytic process.

• Rationale: Co-agglutination is a diagnostic technique used to detect the presence of antigens or antibodies. It involves the agglutination (clumping) of particles, such as bacteria, in the presence of specific antibodies. It does not play a direct role in sensitizing bacteria for phagocytosis.

• Rationale: Neutralization is a process by which antibodies bind to and neutralize pathogens or toxins, preventing them from infecting host cells. While important for immune defense, it does not involve the marking of pathogens for phagocytosis.

• Rationale: Complement fixation is a process where the complement system is activated by antigen-antibody complexes, leading to the destruction of pathogens. While complement proteins can act as opsonins, the term "complement fixation" specifically refers to the activation process, not the opsonization.

• Among the given options, opsonization is the correct term for the serological reaction that sensitizes bacteria for phagocytosis. It enhances the ability of phagocytes to recognize and engulf pathogens, thereby playing a crucial role in the immune response.

• Effective sterilization in an autoclave requires specific conditions of temperature, pressure, and time to ensure the destruction of all forms of microbial life, including bacterial spores.
• The standard condition for autoclave sterilization is 121°C (250°F) at a pressure of 15 pounds per square inch (psi) for a minimum of 30 minutes. This combination of heat, pressure, and exposure time is crucial for ensuring comprehensive sterilization.
• At 121°C, the steam effectively penetrates materials and equipment, allowing for the complete elimination of microorganisms and spores. This temperature, along with the pressure and time, is widely accepted in microbiological and medical practice as the benchmark for autoclave sterilization.

• Rationale: 100°C is the boiling point of water at standard atmospheric pressure. While it can kill many vegetative bacteria, it is insufficient for the sterilization of bacterial spores and other heat-resistant organisms. Therefore, it is not suitable for effective autoclave sterilization.

• Rationale: Although 110°C is hotter than boiling water, it still does not provide the necessary conditions to ensure the complete destruction of all microorganisms and their spores. For autoclaving, higher temperatures are required to achieve a sterile outcome.

• Rationale: 131°C is above the standard required temperature for autoclave sterilization. While this temperature would certainly ensure sterilization, it is higher than necessary and could potentially damage some types of equipment and materials. The standard of 121°C is optimal for both effectiveness and safety.

• Among the given options, 121°C at a pressure of 15 pounds per square inch for 30 minutes is the recognized standard for effective autoclave sterilization. This temperature ensures that all microorganisms, including the most resistant spores, are completely destroyed.

• Mesophilic bacteria are those that grow best in moderate temperature ranges, specifically between 10°C to 50°C. They are commonly found in soil, water, and in the human body, making them a significant group in terms of both health and industry.
• These bacteria are crucial in various biological processes, including fermentation, decomposition of organic matter, and in the human digestive system. Examples include Escherichia coli and Lactobacillus species.

• Rationale: Thermophilic bacteria thrive at relatively high temperatures, typically between 45°C and 80°C. They are often found in hot environments such as hot springs and compost heaps. Examples include Thermus aquaticus and Bacillus stearothermophilus.

• Rationale: Hyperthermophilic bacteria prefer extremely high temperatures, usually above 80°C and up to 122°C. They are often located in extreme environments like hydrothermal vents on the ocean floor. Examples include Pyrolobus fumarii and Methanopyrus kandleri.

• Rationale: Psychrophilic bacteria grow best at cold temperatures, typically between -5°C and 15°C. They are often found in polar regions and deep ocean waters. Examples include Pseudomonas syringae and Arthrobacter species.

• Among the given options, mesophilic bacteria are the ones that grow best between 10°C and 50°C. They play a vital role in various ecosystems and human health, making them a focal point in microbiological studies and applications.

• Iron absorption in the body can be significantly enhanced by the presence of vitamin C, which is abundant in orange juice.
• Vitamin C (ascorbic acid) converts iron into a form that is more easily absorbed by the intestines. It can reduce ferric iron (Fe3+) to ferrous iron (Fe2+), which is more soluble and readily absorbed.
• Consuming orange juice along with an iron supplement can therefore increase the efficiency of iron absorption, making it more effective in treating or preventing iron deficiency anemia.

• Rationale: While baked potatoes do contain some vitamin C, the amount is relatively low compared to orange juice. Therefore, they are not as effective in enhancing iron absorption.

• Rationale: Green beans contain iron and some vitamin C, but again, the concentration of vitamin C is not high enough to significantly enhance the absorption of an iron supplement.

• Rationale: Fortified milk is often enriched with vitamins and minerals, but it also contains calcium, which can inhibit iron absorption. Calcium competes with iron for absorption in the intestines, making it less effective as a complement to iron supplements.

• Among the given options, orange juice is the most effective in enhancing the absorption of an iron supplement due to its high vitamin C content. Consuming it along with iron supplements can improve iron absorption and help in better management of iron deficiency conditions.

• Hand hygiene supports the body's first line of defense against infections, which is a crucial component of innate immunity.
• Innate immunity consists of physical, chemical, and cellular defenses that are always ready to protect the body from pathogens. This includes barriers like the skin and mucous membranes, as well as protective responses like inflammation and phagocytosis.
• By practicing effective hand hygiene (such as washing with soap and water or using hand sanitizer), individuals can remove or kill many pathogens before they have the chance to enter the body and cause infection.

• Rationale: Adaptive immunity involves specific responses to pathogens that the body has previously encountered. It includes the activation of lymphocytes and the production of antibodies. While hand hygiene indirectly supports the overall immune system by reducing pathogen load, it does not specifically enhance adaptive immune responses.

• Rationale: Humoral immunity is a subset of adaptive immunity that involves the production of antibodies by B cells. These antibodies target specific pathogens. Hand hygiene reduces the risk of infections in general but does not directly support the production of specific antibodies.

• Rationale: Cell-mediated immunity, another subset of adaptive immunity, involves T cells that directly attack infected or cancerous cells. While effective hand hygiene reduces the likelihood of infections, it does not specifically enhance the function of T cells.

• Hand hygiene directly supports innate immunity by providing an essential barrier to prevent the entry of pathogens into the body. Understanding the role of innate immunity helps emphasize the importance of basic hygiene practices in infection prevention.