Microbiology- Bacteria And Virus MCQ Test

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  • 1/47 Questions

    A 32-year-old patient with advanced AIDS, after some antimicrobial treatment, reports symptoms of esophageal dysphagia, a feeling that - after swallowing food sticks to the base of the throat. when you look at his mouth, you notice whitish coatings that can be easily removed and show the vivid red ground underneath. The most likely etiological factor of this conditions is:

    • Herpes simplex virus
    • Micrococcus luteus
    • Hepatitis C virus
    • Candida species 
    • Streptococcus pneumoniae
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About This Quiz

Microbiology is a discipline of biology focused on the study of microorganisms-unicellular, multicellular, or acellular. This test is about bacteria and viruses and the infection caused by them on the human body. How much do you know about it? Well, let's take this quiz and see for yourself.

Microbiology- Bacteria And Virus MCQ Test - Quiz

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  • 2. 

    Which of the following conditions would initiate high-level transcription of the lac operon of Escherichia coli?

    • Low levels of glucose in the cell, and lactose present in the medium

    • High levels of glucose in the cell, and lactose present in the medium

    • Low levels of lactose in the call and glucose present in the medium

    • High levels of glucose in the cell, no lactose in the medium

    Correct Answer
    A. Low levels of glucose in the cell, and lactose present in the medium
    Explanation
    The lac operon of Escherichia coli is a gene system that regulates the metabolism of lactose. It is under the control of an inducible promoter, meaning that it is only transcribed when lactose is present and glucose is scarce. In this case, the correct answer states that transcription of the lac operon would be initiated when there are low levels of glucose in the cell and lactose is present in the medium. This condition signals the cell to switch to utilizing lactose as an energy source since glucose is not available in sufficient amounts.

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  • 3. 

    The Virologist is going to culture the unknown, not well characterized, dsDNA-containing, most likely oncogenic, a human pathogen. He is not sure yet what type of cell culture will be most suitable for this microorganism. He decided to perform his experiment using cells, subculturing od which is difficult. He has obtained them directly from the hamster, most likely he will use which cell culture?

    • Escherichia coli cell culture

    • Diploid cell culture

    • Chlamydia species culture

    • Continuous cell culture

    • Transformed cell culture

    • Primary cell culture

    Correct Answer
    A. Transformed cell culture
    Explanation
    The virologist is working with an unknown, potentially oncogenic human pathogen that is dsDNA-containing. Since subculturing the cells is difficult, the virologist needs a cell culture that can be easily maintained and passaged. Transformed cell cultures are derived from cells that have been genetically modified to become immortal and have an increased growth rate. These cells are commonly used in research because they can be easily cultured and manipulated. Therefore, it is likely that the virologist will use a transformed cell culture for his experiment.

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  • 4. 

    Point at the vaccine effective against the most pathogenic type pf Haemophilus species, Gram-negative highly fastidious bacteria responsible for life-threatening invasive infections in small children:

    • Saccharide-based pure

    • Killed

    • Fractional

    • Live attenuated

    • Toxoid

    • Protein-based subunit

    Correct Answer
    A. Live attenuated
    Explanation
    Live attenuated vaccines are created by weakening the pathogen so that it can still stimulate an immune response but not cause disease. In the case of Haemophilus species, live attenuated vaccines have been found to be the most effective in preventing invasive infections in small children. This type of vaccine is able to provide a strong and long-lasting immune response against the pathogen, making it an ideal choice for protection against this highly fastidious bacteria.

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  • 5. 

    A relatively fixed group of microorganisms regularly found in a given area of the body at a given age is called:

    • Resident flora/microbiota, including Enterococcus spp.

    • Transient flora/microbiota, including Staphylococcus spp.

    • Opportunistic pathogens, including Micrococcus sp.

    • Fastidious microbiota, including Staphylococcus spp.

    • Strictly pathogenic bacteria, including Staphylococcus spp.

    Correct Answer
    A. Resident flora/microbiota, including Enterococcus spp.
    Explanation
    The correct answer is resident flora/microbiota, including Enterococcus spp. This term refers to a relatively fixed group of microorganisms that are regularly found in a specific area of the body at a specific age. Enterococcus spp. are a type of bacteria that can be part of the resident flora. The other options are not accurate descriptions of this concept. Transient flora/microbiota refers to microorganisms that are temporarily present on the body, opportunistic pathogens are microorganisms that can cause infection in certain circumstances, fastidious microbiota refers to microorganisms with specific growth requirements, and strictly pathogenic bacteria refers to bacteria that are always pathogenic and cause disease.

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  • 6. 

    Reduction of microbial rate, with the exception of psychrotrophs (e.g. pathogenic Listeria monocytogenes will be multiplying), will be achieved in:

    • 31 Celcius

    • 35 Celcius

    • -2 Celcius

    • -6 Celcius

    • 6 Celcius

    Correct Answer
    A. 6 Celcius
    Explanation
    At a temperature of 6 degrees Celsius, the microbial rate will be reduced. This is because most microorganisms have an optimal temperature for growth, and when the temperature is lower than this optimal range, their growth and multiplication slow down. However, it is important to note that psychrotrophs, such as the pathogenic Listeria monocytogenes mentioned in the question, can still multiply at lower temperatures.

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  • 7. 

    What is the clinical meaning of methicillin-reistant coagulase-negative Staphylococcus spp.

    • Resistant to all beta-lactam antimicronials with exception of ceftobiprole and ceftaroline

    • Resistant to penicillins and 1st generation of cephalosporins 

    • Resistamt to penicillins and cephalosporins of all generations (with exception of cefepime) with and without beta-lactamase inhibitors 

    • Resistance to penicillins and cephalosporins of all generations without beta-lactamase inhibitors and monobactams

    • Resistance to all the beta-lactam antibiotics 

    Correct Answer
    A. Resistance to all the beta-lactam antibiotics 
    Explanation
    The clinical meaning of methicillin-resistant coagulase-negative Staphylococcus spp. that is resistant to all beta-lactam antibiotics is that it is resistant to a wide range of antibiotics commonly used to treat bacterial infections. This includes penicillins, cephalosporins, and other beta-lactam antibiotics. This type of resistance can make it difficult to effectively treat infections caused by this strain of Staphylococcus, and alternative antibiotics may need to be used.

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  • 8. 

    Which of the following belong to the group of beta-lactam antimicrobials and are active against mecA gene-containing bacteria?

    • Macrolides

    • Monobactams

    • Carbapenems

    • Beta-lactamase inhibitors

    • Cephalosporins 5th generation

    • Penicillins

    Correct Answer
    A. Carbapenems
    Explanation
    Carbapenems belong to the group of beta-lactam antimicrobials and are active against mecA gene-containing bacteria. They are broad-spectrum antibiotics that are effective against a wide range of bacteria, including those that produce beta-lactamase enzymes. Carbapenems are often used as a last resort treatment for serious infections caused by multidrug-resistant bacteria.

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  • 9. 

    Staphylococci are Gram-positive because they:

    • Appear in grape-like structures under the microscope

    • Use LPS in pathogenesis

    • Have sterols in outer and inner cellular membrane

    • Have thick protective peptidoglycan layer

    • Undergo rapid binary fission

    Correct Answer
    A. Have thick protective peptidoglycan layer
    Explanation
    Staphylococci are Gram-positive because they have a thick protective peptidoglycan layer. Gram-positive bacteria have a thick peptidoglycan layer in their cell wall, which retains the crystal violet stain during the Gram staining process. This causes them to appear purple under a microscope. In contrast, Gram-negative bacteria have a thinner peptidoglycan layer and an outer membrane, causing them to appear pink after the counterstain is applied.

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  • 10. 

    Toxoid vaccine is made from a bacterial toxin that has been made harmless but that elicits an immune response against this toxin. the currently available toxoid vaccine protects against disease caused by the following toxin-releasing bacterium:

    • Streptococcus pneumoniae

    • Haemophilius influenzae

    • Corynebacterium diphtheriae

    • Neisseria meningitidis 

    • Vibrio cholerae

    Correct Answer
    A. Streptococcus pneumoniae
    Explanation
    Toxoid vaccines are made from bacterial toxins that have been inactivated but can still stimulate an immune response. The correct answer, Streptococcus pneumoniae, is a bacterium that releases toxins. Therefore, a toxoid vaccine can be used to protect against diseases caused by Streptococcus pneumoniae.

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  • 11. 

    Your patient came for a visit with a black lesion on the skin surrounded by inflamed skin. The swab was taken and on culture, large colonies grew on agar-agar medium. On the 2nd day the Gram staining was done revealing Gram-positive long bacilli with centrally localized spores. Your suspect Bacillus sp. Which are:

    • Aerobes

    • Aerotolerants

    • Anaerobes

    • Facultative anaerobes

    • Microaerophiles

    Correct Answer
    A. Aerobes
    Explanation
    Based on the information provided, the large colonies that grew on the agar-agar medium indicate that the bacteria require oxygen to grow, suggesting that they are aerobic organisms. Additionally, the presence of Gram-positive long bacilli with centrally localized spores further supports the identification of the bacteria as Bacillus sp., which are known to be aerobic bacteria.

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  • 12. 

    Which of the following media do you need to use to transport urine from the hospital to the lab?

    • Transport- diagnostic

    • Selective-differential 

    • Solid

    • Liquid

    • Enriched

    Correct Answer
    A. Transport- diagnostic
    Explanation
    To transport urine from the hospital to the lab, the media that need to be used is "Transport- diagnostic". This media is specifically designed for the transportation of diagnostic specimens, such as urine, to ensure their integrity and prevent contamination. It provides the necessary conditions to maintain the viability and characteristics of the specimen during transportation, allowing accurate analysis in the lab.

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  • 13. 

    Which of the Cephalosporins is active against methicillin-resistant Staphylococcus.aureus?

    • Cefotaxime

    • Cefepime

    • Ceftriaxone

    • Cefoxitin

    • Ceftazidime

    • Ceftaroline

    Correct Answer
    A. Ceftaroline
    Explanation
    Ceftaroline is active against methicillin-resistant Staphylococcus aureus (MRSA) because it has been specifically designed to target and inhibit the enzymes responsible for methicillin resistance in Staphylococcus aureus bacteria. This makes ceftaroline an effective treatment option for infections caused by MRSA. The other cephalosporins listed may be effective against other strains of Staphylococcus aureus, but they are not specifically active against MRSA.

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  • 14. 

    Point at the compound found in saliva or tears, that destroys bacteria:

    • Lysozyme

    • Collagenase

    • Endotoxin

    • Hyaluronidase

    • Lactic acid

    Correct Answer
    A. Lysozyme
    Explanation
    Lysozyme is an enzyme found in saliva and tears that plays a crucial role in destroying bacteria. It works by breaking down the cell walls of bacteria, causing them to burst and die. This antibacterial action helps to protect the body from infections and maintain oral and ocular health.

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  • 15. 

    Which of the following classes of antimicrobial agents are narrow spectrum and primarily the one useful against aerobic Gram-negative bacteria?

    • Aminoglycosides

    • Glycopeptidase

    • Lipopeptidase

    • Lincosamides

    • Nitroimidazoles

    Correct Answer
    A. Aminoglycosides
    Explanation
    Aminoglycosides are narrow spectrum antimicrobial agents primarily useful against aerobic Gram-negative bacteria. They work by inhibiting protein synthesis in bacteria, specifically targeting the 30S ribosomal subunit. Aminoglycosides are not effective against anaerobic bacteria or Gram-positive bacteria. These drugs are commonly used to treat infections caused by organisms such as Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae.

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  • 16. 

    Which of the following is a limitation of the autoclave?

    • It lacks the ability to inactivate HIV

    • It can't be used to sterilize glass Petri dishes with bacterial cultures

    • It will destroy some plastic Eppendorf's

    • Requires a lot of chemical substances into it

    • It lacks the ability to kill clostridium spp.

    Correct Answer
    A. It will destroy some plastic Eppendorf's
    Explanation
    The autoclave is a device used for sterilization, but one of its limitations is that it can destroy some plastic Eppendorf's. This means that certain types of plastic containers used in laboratories may not be suitable for sterilization in an autoclave, as they could be damaged or melted during the process. It is important to choose the appropriate materials for sterilization to avoid any potential damage or contamination.

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  • 17. 

    Catabolite activator protein (CAP) acts as the sensor of:

    • Glucose

    • Maltose

    • Mannitol

    • Lactose

    • Sucrose

    Correct Answer
    A. Glucose
    Explanation
    Catabolite activator protein (CAP) acts as the sensor of glucose. This protein is involved in the regulation of gene expression in response to glucose levels in the cell. When glucose is present, CAP binds to it and undergoes a conformational change, allowing it to bind to DNA and activate the transcription of genes involved in glucose metabolism. This mechanism helps the cell efficiently utilize glucose as an energy source.

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  • 18. 

    Point at the most common carbapenemase currently?

    • KPC

    • NDM-1

    • VIM

    • IMP

    • OXA-48

    Correct Answer
    A. KPC
    Explanation
    KPC is the most common carbapenemase currently. This enzyme is responsible for resistance to carbapenem antibiotics, which are commonly used to treat severe infections. KPC is widely spread among Gram-negative bacteria, particularly Klebsiella pneumoniae. It poses a significant threat to public health due to its ability to spread rapidly and its resistance to multiple antibiotics.

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  • 19. 

    Which of the following laboratory techniques used in the diagnostics of viral infections is based on antigen-antibody interaction?

    • Complement fixation test

    • Enzyme-linked immunosorbent assay

    • CPE neutralization test

    • Nucleic acid hybridization

    • Hemagglutination inhibition test

    • Western blot

    Correct Answer
    A. Nucleic acid hybridization
    Explanation
    Nucleic acid hybridization is a laboratory technique used in the diagnostics of viral infections that is based on antigen-antibody interaction. This technique involves the hybridization of a labeled nucleic acid probe with the viral nucleic acid in a patient sample. The probe is designed to specifically bind to the viral nucleic acid, allowing for the detection and identification of the virus. This technique is commonly used to detect and diagnose viral infections, as it can provide rapid and accurate results.

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  • 20. 

    The lab analysis has shown that a 24-year-old female patient suffers from meningitis caused by the virus (multinucleated giant cells are being seen in the tissue culture). Point at the most probable factor for this condition:

    • Herpesvirus

    • Poliovirus

    • Human immunodeficiency virus

    • Polyomavirus

    • Rabies virus

    Correct Answer
    A. Herpesvirus
    Explanation
    The most probable factor for the patient's condition is the Herpesvirus. This is indicated by the presence of multinucleated giant cells in the tissue culture, which is a characteristic feature of herpesvirus infection. Meningitis can be caused by various pathogens, but the presence of multinucleated giant cells specifically points towards a viral etiology, with herpesvirus being the most likely culprit in this case.

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  • 21. 

    Which of the following methods used to control the level of microbial contamination uses 135 celsius for 15 mins?

    • Pasteurization 

    • Decoction

    • Steam sterilization 

    • Tyndallization

    • Flaming

    Correct Answer
    A. Steam sterilization 
    Explanation
    Steam sterilization is the method used to control the level of microbial contamination that uses 135 degrees Celsius for 15 minutes. This process involves exposing the objects or substances to high-pressure saturated steam at a specified temperature and time to kill or inactivate microorganisms. It is commonly used in medical and laboratory settings to sterilize equipment and instruments, as well as in food processing to ensure the safety and preservation of food products.

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  • 22. 

    Sputum testing revealed the presence of acid-fast bacteria called?

    • Mycobacterium sp.

    • Staphylococcus sp.

    • Candida sp.

    • Streptococcus sp.

    • Bacillus sp.

    Correct Answer
    A. Mycobacterium sp.
    Explanation
    The presence of acid-fast bacteria in sputum testing suggests the presence of Mycobacterium sp. Acid-fast bacteria are characterized by their ability to retain a specific stain even after being washed with acid, and Mycobacterium is a genus of bacteria that includes species such as Mycobacterium tuberculosis, the causative agent of tuberculosis. Staphylococcus, Candida, Streptococcus, and Bacillus are not typically acid-fast bacteria and are less likely to be found in sputum testing.

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  • 23. 

    Point at the most sensitive method of bacterial identification:

    • Agglutination test

    • PCR method

    • Enzyme immunoassay

    • Catalase test

    • API test

    Correct Answer
    A. PCR method
    Explanation
    PCR method is the most sensitive method of bacterial identification because it allows for the amplification of specific DNA sequences, making it highly accurate and sensitive in detecting even small amounts of bacterial DNA. This technique can identify bacteria based on their genetic material, providing rapid and reliable results. Additionally, PCR can be used to detect multiple bacterial species simultaneously, making it a versatile tool in bacterial identification.

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  • 24. 

    The level of serum transaminases, enzymes that catalyze the interconversion of amino acids and oxoacids by transfer of amino groups, increases significantly during infection caused by:

    • Hepatotrophic viral species

    • Syncytium-producing viral species

    • Spore-forming bacterial species

    • Strictly anaerobic bacterial species

    • Fastidious bacterial species

    Correct Answer
    A. Spore-forming bacterial species
  • 25. 

    Injection of foreign DNA by a bacteriophage into the host bacterium is called:

    • Conjegation

    • Transformation

    • Co-transformation

    • Transduction

    • Transfection

    Correct Answer
    A. Transduction
    Explanation
    Transduction is the correct answer because it refers to the process in which a bacteriophage injects foreign DNA into a host bacterium. This transfer of genetic material allows the bacteriophage to infect the bacterium and replicate. The term "transduction" specifically describes the transfer of DNA through a bacteriophage, distinguishing it from other mechanisms such as conjugation (direct transfer of DNA between bacteria) and transformation (uptake of free DNA by a bacterium). Transfection, on the other hand, refers to the introduction of foreign DNA into eukaryotic cells, not bacteria.

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  • 26. 

    A 34-year-old pregnant women living in London presents to the emergency room complaint of fatigue, loss of appetite, and nausea. She has a low-grade fever and yellowish pigmentation of the skin and whites of the eyes. Mild infection with hepatotropic causative agent:

    • HAV

    • HEV

    • HBV

    • HCV

    • HDV

    Correct Answer
    A. HEV
    Explanation
    The correct answer is HEV (Hepatitis E Virus). Hepatitis E is a viral infection that primarily affects the liver. It is transmitted through the fecal-oral route, often through contaminated water or food. Symptoms include fatigue, loss of appetite, nausea, fever, and jaundice (yellowing of the skin and eyes). Pregnant women are particularly susceptible to severe complications from Hepatitis E, including liver failure and death. Therefore, given the patient's symptoms and pregnancy status, HEV is the most likely causative agent.

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  • 27. 

    Which of the following antimicrobial agents has activity against VRE-positive strains?

    • Teicoplanin

    • Vancomycin

    • Colistin

    • Linezolid

    • Aztreonam

    Correct Answer
    A. Linezolid
    Explanation
    Linezolid has activity against VRE-positive strains. VRE stands for Vancomycin-resistant Enterococci, which are bacteria that have developed resistance to the antibiotic vancomycin. Linezolid is an antimicrobial agent that is effective against these resistant strains of bacteria. It works by inhibiting protein synthesis in the bacteria, preventing their growth and replication. Therefore, linezolid is a suitable treatment option for infections caused by VRE-positive strains.

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  • 28. 

    Microorganisms that may grow in aerobic and anaerobic conditions, and the presence of oxygen does not influence their growth, but which grow better in the higher concentrations of carbon dioxide, are called?

    • Capnophiles

    • Microaerophiles

    • Aerophiles

    • Mesophiles

    • Aerotolerants

    Correct Answer
    A. Capnophiles
    Explanation
    Capnophiles are microorganisms that can grow in both aerobic and anaerobic conditions, and the presence of oxygen does not affect their growth. However, they prefer higher concentrations of carbon dioxide for optimal growth. This preference for elevated levels of carbon dioxide distinguishes capnophiles from other microorganisms that may grow in similar conditions but do not show a preference for carbon dioxide.

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  • 29. 

    A 10-year-old girl is brought in to your office by her mother with cystitis. The child complains of pain and burning sensation when passing urine. A urinalysis was positive for leukocytes, blood and bacteria. Midstream urine culture showed the pink colonies on MacConkey agar. Point at the most likely causative agent of this case of urinary tract infection:

    • Streptococcus agalactiae

    • Pseudomonas aeruginosa

    • Klebsiella pneumoniae

    • Acinetobacter baumannii

    • Staphylococcus saprophyticus

    Correct Answer
    A. Staphylococcus saprophyticus
    Explanation
    Staphylococcus saprophyticus is the most likely causative agent of this case of urinary tract infection. This is supported by the symptoms reported by the patient, such as pain and burning sensation during urination, as well as the positive urinalysis results for leukocytes, blood, and bacteria. Staphylococcus saprophyticus is a common cause of urinary tract infections in young sexually active females, and its presence on the MacConkey agar confirms its identification as the causative agent in this case.

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  • 30. 

    Human parainfluenza virus type 1 (hPIV-1), the most common cause of croup (laryngotracheobronchitis), is spread mainly via:

    • Air conditioning

    • Sexual way

    • Contaminated food

    • Placenta

    • Respiratory droplets

    Correct Answer
    A. Air conditioning
    Explanation
    The correct answer is "Respiratory droplets". Human parainfluenza virus type 1 (hPIV-1) is primarily spread through respiratory droplets, which are produced when an infected person coughs or sneezes. These droplets can then be inhaled by others in close proximity, leading to the transmission of the virus. Air conditioning, sexual contact, contaminated food, and the placenta are not recognized as common modes of transmission for hPIV-1.

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  • 31. 

    A 42-year-old woman has received her Pap test result: atypical squamous cells of undetermined significance. This examination is performed to exclude the infection with:

    • Human immunodeficiency virus

    • Human metapneumovirus

    • Molluscum contagiosum virus

    • Human herpesvirus type 8

    • Human papilloma virus

    Correct Answer
    A. Human immunodeficiency virus
    Explanation
    The Pap test is performed to detect abnormal changes in the cells of the cervix, which can be caused by various factors including infections. Atypical squamous cells of undetermined significance (ASC-US) is a result that indicates the presence of abnormal cells, but it is not specific enough to determine the exact cause. However, one of the potential causes of ASC-US is infection with the human papilloma virus (HPV), which is known to increase the risk of cervical cancer. Since HPV is commonly associated with sexually transmitted infections, it is important to consider the possibility of other sexually transmitted infections as well, including human immunodeficiency virus (HIV). Therefore, the Pap test result of ASC-US may prompt further investigation for HIV infection.

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  • 32. 

    Which of the following diarrheagenic pathotypes of Escherichia coli can produce toxin in terms of both structure and function closely related to Shiga toxin produced by Shigella dysenteriae type 1?

    • ETEC

    • EHEC

    • EPEC

    • EIEC

    • EAEC

    Correct Answer
    A. ETEC
    Explanation
    ETEC stands for Enterotoxigenic Escherichia coli. This pathotype of E. coli can produce a toxin that is closely related to the Shiga toxin produced by Shigella dysenteriae type 1. This toxin is responsible for causing diarrhea. ETEC is a common cause of traveler's diarrhea and is typically acquired through contaminated food or water.

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  • 33. 

    Point at the microorganism that neither can be stained with Gram-method nor can be cultured:

    • Treponema pallidum

    • Streptococcus agalactiae

    • Neisseria gonorrhoeae

    • Haemophilus influenzae

    • Legionella pneumophila

    Correct Answer
    A. Treponema pallidum
    Explanation
    Treponema pallidum is the correct answer because it is a microorganism that cannot be stained with the Gram-method, which is a common staining technique used to classify bacteria into Gram-positive and Gram-negative. Additionally, Treponema pallidum cannot be cultured, meaning it cannot be grown and replicated in a laboratory setting. This makes it difficult to study and diagnose infections caused by this microorganism.

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  • 34. 

    A 30-year-old woman presents to her physician complaining of a slightly increased, malodorous discharge that is grey-white in color. The microscopic examination of the discharge reveals the presence of clue cells. Which of the following organisms, the crucial component of vaginal microbiota, would prevent the bacterial vaginosis in this patient?

    • Staphylococcus aureus

    • Lactobacillus 

    • Escherichia coli

    • Gardnerella vaginalis

    • Candida albicans

    Correct Answer
    A. Lactobacillus 
    Explanation
    Lactobacillus acidophilus is the crucial component of vaginal microbiota that would prevent bacterial vaginosis in this patient. This organism helps maintain a healthy vaginal pH by producing lactic acid, which creates an acidic environment that inhibits the growth of harmful bacteria like Gardnerella vaginalis. Bacterial vaginosis occurs when there is an overgrowth of Gardnerella vaginalis, leading to a disruption of the normal vaginal microbiota and an increase in malodorous discharge.

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  • 35. 

    Point at the microorganism responsible for nongonococcal urethritis:

    • Enterococcus faecalis

    • Mycoplasma hominis

    • Streptococcus agalactiae

    • Klebsiella granulomatis

    • Staphylococcus saprophyticus

    Correct Answer
    A. Mycoplasma hominis
    Explanation
    Mycoplasma hominis is the correct answer because it is a known microorganism responsible for nongonococcal urethritis. This condition is characterized by inflammation of the urethra that is not caused by gonorrhea. Mycoplasma hominis is a type of bacteria that can infect the urogenital tract and lead to symptoms such as urethral discharge and discomfort during urination. Other microorganisms listed in the options, such as Enterococcus faecalis, Streptococcus agalactiae, Klebsiella granulomatis, and Staphylococcus saprophyticus, are not typically associated with nongonococcal urethritis.

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  • 36. 

    A 2-year-old child suffered from epiglottitis. Culture of the specimen revealed the bacterial growth only on the chocolate agar. Gram-negative coccobacilli were found under the microscope. The mother claimed that the child was not vaccinated against encapsulated bacteria. The most likely species responsible for the infection is:

    • Escherichia coli

    • Streptococcus pneumoniae

    • Streptococcus pneumoniae

    • Neisseria meningitidis

    • Haemophilus influenzae

    Correct Answer
    A. Haemophilus influenzae
    Explanation
    The correct answer is Haemophilus influenzae. This bacterium is known to cause epiglottitis, which is an infection of the epiglottis, a flap of tissue that prevents food from entering the windpipe. Haemophilus influenzae is a Gram-negative coccobacillus and is commonly associated with infections in children, especially those who have not been vaccinated against encapsulated bacteria. The fact that the bacterial growth was only observed on chocolate agar further supports the identification of Haemophilus influenzae, as this bacterium requires specific growth conditions provided by chocolate agar.

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  • 37. 

    Point at the disease caused by bacteria that lack a cell wall and a periplasmic space, and have reduced genomes and limited metabolic activity (lack of some genes necessary for amino acid synthesis

    • Walking pneumonia

    • Whooping cough

    • Tuberculosis

    • Scarlet fever

    • Diphtheria

    Correct Answer
    A. Walking pneumonia
    Explanation
    Walking pneumonia is the correct answer. Walking pneumonia is typically caused by the bacteria Mycoplasma pneumoniae, which lack a cell wall and a periplasmic space. These bacteria have reduced genomes and limited metabolic activity, including the lack of some genes necessary for amino acid synthesis. This results in a milder form of pneumonia that can be walked through, hence the name "walking pneumonia."

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  • 38. 

    Point at the virulence factor important for the pathogenesis of whooping cough:

    • Lecitinase

    • Exfoliative toxin

    • Beta-hemolysin

    • Tracheal cytotoxin

    • Alpha-toxin

    Correct Answer
    A. Tracheal cytotoxin
    Explanation
    Tracheal cytotoxin is an important virulence factor for the pathogenesis of whooping cough. It is a toxin that specifically targets and damages the ciliated cells lining the trachea, leading to the characteristic symptoms of the disease. This toxin inhibits the movement of the cilia, impairing the clearance of mucus and bacteria from the airways, and causing inflammation and coughing. By targeting the tracheal cells, tracheal cytotoxin plays a crucial role in the development and progression of whooping cough.

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  • 39. 

    Which of the following urinary tract infection pathogens is most common in sexually-active pre-menopausal women?

    • Enterococcus faecalis

    • Pseudomonas aeruginosa

    • Proteus mirabilis

    • Acinetobacter baumannii

    • Staphylococcus saprophyticus

    • Klebsiella pneumoniae

    Correct Answer
    A. Staphylococcus saprophyticus
    Explanation
    Staphylococcus saprophyticus is the most common urinary tract infection (UTI) pathogen in sexually-active pre-menopausal women. This bacterium is commonly found in the genital area and can easily enter the urinary tract during sexual activity. It has a higher propensity to cause UTIs in this population compared to other pathogens listed.

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  • 40. 

    A 52-year-old man suffers from chancroid. Point at the pathogen responsible for this condition:

    • Staphylococcus aureus

    • Shigella dysenteriae type 1

    • Molluscum contagiosum virus

    • Haemophilus ducreyi

    • Treponema pallidum

    Correct Answer
    A. Haemophilus ducreyi
    Explanation
    Haemophilus ducreyi is the pathogen responsible for chancroid, a sexually transmitted infection characterized by painful genital ulcers. Staphylococcus aureus is not associated with chancroid, but it can cause other types of infections. Shigella dysenteriae type 1 causes dysentery, a condition characterized by severe diarrhea. Molluscum contagiosum virus causes a skin infection characterized by raised, pearl-like bumps. Treponema pallidum is the causative agent of syphilis, another sexually transmitted infection, but it is not responsible for chancroid.

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  • 41. 

    The patient was diagnosed with pulmonary nocardiosis. Gram staining of sputum revealed:

    • Gram-positive cocci

    • Gram-negative rods

    • Gram-positive rods

    • Gram-negative spore-forming rods

    • Gram-positive cocci

    Correct Answer
    A. Gram-positive rods
    Explanation
    The patient was diagnosed with pulmonary nocardiosis based on the Gram staining of the sputum sample. The presence of Gram-positive rods in the staining indicates the presence of Nocardia species, which are known to cause nocardiosis. This staining result is consistent with the diagnosis of pulmonary nocardiosis.

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  • 42. 

    A female medical student is admitted to the emergency department with symptoms of severe urinary tract infection. Gram-negative, facultatively anaerobic, motile, lactose-negative rods are being isolated from the middle-stream urine sample. Which is the most likely causative agent of this infection?

    • Citrobacter freundii

    • Providencia stuartii

    • Proteus vulgaris

    • Klebsiella pneumoniae

    • Enterobacter cloacae

    Correct Answer
    A. Proteus vulgaris
    Explanation
    Proteus vulgaris is the most likely causative agent of this severe urinary tract infection. This is because Proteus species, including P. vulgaris, are known to be gram-negative, facultatively anaerobic, motile, and lactose-negative rods, which matches the characteristics of the bacteria isolated from the urine sample. Additionally, Proteus species are commonly associated with urinary tract infections, making it the most likely causative agent in this case.

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  • 43. 

    The greatest success of vaccination programs was the eradication of smallpox. The following type of vaccine has been used:

    • Recombinant

    • Toxoid

    • Killed

    • Live-attenuated

    • Live

    Correct Answer
    A. Live
    Explanation
    Live vaccines contain weakened or attenuated forms of the virus or bacteria that cause the disease. When administered, these vaccines stimulate the immune system to produce a response similar to a natural infection, without causing severe illness. Live vaccines have been highly effective in preventing diseases like smallpox because they create a strong and long-lasting immune response. The use of live vaccines in smallpox eradication campaigns played a crucial role in eliminating the disease worldwide.

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  • 44. 

    Necrotizing fasciitis was diagnosed in a 57-year-old woman. It developed after trauma. Erythema, pain, and edema quickly progressed to central patches of blue discoloration. On the fourth day, the involved area became gangrenous. This condition most likely was caused by:

    • Enterococcus faecium

    • Neisseria meningitidis

    • Escherichia coli

    • Streptococcus pyogenes

    • Actinomyces israelii

    Correct Answer
    A. Streptococcus pyogenes
    Explanation
    The correct answer is Streptococcus pyogenes. Necrotizing fasciitis is a severe soft tissue infection caused by certain bacteria, and Streptococcus pyogenes is one of the most common causative organisms. The progression of symptoms described in the question, including erythema, pain, edema, and the development of gangrene, is consistent with the clinical presentation of necrotizing fasciitis caused by Streptococcus pyogenes.

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  • 45. 

    Point at the virus that is causing vaccine-preventable acute gastroenteritis:

    • Calicivirus

    • Rotavirus

    • Norovirus

    • Adenovirus

    • Astrovirus

    Correct Answer
    A. Rotavirus
    Explanation
    Rotavirus is the correct answer because it is a well-known and common cause of vaccine-preventable acute gastroenteritis. It is highly contagious and can cause severe diarrhea and vomiting, especially in young children. Vaccines have been developed to prevent rotavirus infection and reduce the risk of gastroenteritis.

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  • 46. 

    Point at the species responsible for acute gastroenteritis via release of toxins binding to specific enterocyte receptors and causing the release of chloride ions into the intestinal lumen, and leading to secretory diarrhea:

    • Shigella dysenteriae

    • Staphylococcus aureus

    • Clostridioides difficile

    • Enterococcus faecalis

    • Shigella sonnei

    Correct Answer
    A. Shigella dysenteriae
    Explanation
    Shigella dysenteriae is the correct answer because it is known to cause acute gastroenteritis by releasing toxins that bind to specific enterocyte receptors. This binding leads to the release of chloride ions into the intestinal lumen, resulting in secretory diarrhea.

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  • 47. 

    A 43-year-old man reported perifollicular, chronic, pustular infection of the bearded region. New crops of pustules frequently appeared, especially after shaving. He observed a slow spread. Most likely this condition caused by Staphylococcus aureus may be treated with:

    • Acyclovir

    • Colistin

    • Cloxacillin

    • Teicoplanin

    • Vancomycin

    Correct Answer
    A. Vancomycin
    Explanation
    Vancomycin is the correct answer because it is an antibiotic that is effective against Staphylococcus aureus, which is the most likely cause of the chronic, pustular infection in the bearded region. It is commonly used to treat skin and soft tissue infections caused by Staphylococcus aureus, including those that are resistant to other antibiotics. The fact that new crops of pustules frequently appear, especially after shaving, suggests that the infection is persistent and may require a more potent antibiotic like vancomycin.

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  • Current Version
  • Dec 08, 2023
    Quiz Edited by
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  • Feb 05, 2021
    Quiz Created by
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