Microbiology and Immunology 4100A Lecture Notes - Lecture 16: Cytotoxicity, Enterotoxin, Exotoxin

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22 Dec 2019

School

Western University

Department

Microbiology and Immunology

Course

Microbiology and Immunology 4100A

Professor

Martin Mc Gavin

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Related Questions

1) What clinical manifestation do Staphylococcus aureus and Staphylococcus epidermidis share? A) nosocomial infections B) protein A antiphagocytic factor C) hyaluronidase enzyme D) enterotoxins E) staphylokinase 2) Which of the following has been historically classified as Gram-negative bacteria but is genetically more similar to low G + C Gram-positive bacteria? A) mycoplasmas B) Mycobacterium C) Clostridium D) Propionibacterium E) Nocardia 3) What is one virulence factor that differentiates Staphylococcus aureus from other species of staphylococci? A) It has a capsule. B) It can produce coagulase. C) It produces catalase. D) It can live on the surface of the skin and in cutaneous oil glands. E) It produces lipase. 4) Over 90% of Staphylococcus aureus isolates are penicillin-resistant. Why? A) They have loosely organized polysaccharide slime layers. B) They produce coagulase. C) Cell division occurs in successively different planes, and the daughter cells remain attached to one another. D) They produce Î²-lactamase. E) They produce staphylokinase, which dissolves fibrin threads in blood clots. 5) A woman comes to the emergency department with fever and vomiting. She soon develops a red rash all over her body, and her blood pressure begins to drop. What is one possible diagnosis? A) erysipelas C) scarlet fever B) endocarditis D) toxic shock syndrome E) staphylococcal food poisoning 6) Bacteria collected from a severely inflamed wound are sent to the lab for analysis. The results come back as follows: Gram-positive cocci in irregular clusters, kinase and coagulase positive, and able to grow in the presence of most antibiotics except vancomycin. The bacteria in the wound are most likely _______ A) Enterococcus. C) Staphylococcus aureus. B) Staphylococcus epidermidis. D) methicillin-resistant Staphylococcus aureus (MRSA). E) Streptococcus pyogenes (group A streptococcus). 7) Which of the following statements about "flesh-eating" streptococci is FALSE? A) It is caused by a group A streptococcus. B) It is also known as necrotizing fasciitis because it travels along the fascia. C) It causes death in over 50% of cases. D) It is considered a common complication of pyoderma. E) It involves toxemia. 8) Streptococcus agalactiae is associated with which of the following diseases? A) neonatal bacteremia B) neonatal meningitis C) neonatal pneumonia D) both neonatal bacteremia and neonatal meningitis E) neonatal bacteremia, neonatal meningitis, and neonatal pneumonia 9) What differentiates virulent strains of Streptococcus pneumoniae from nonvirulent strains? A) the species-specific teichoic acid present in its cell wall B) the type of Lancefield antigen it produces C) the presence of a polysaccharide capsule that protects it from digestion after endocytosis D) the type of toxins it produces E) the extent of the hemolytic zone it produces when it is grown on blood agar 10) Otitis media may lead to dangerous meningitis in children due to infection with _____ A) Streptococcus agalactiae. B) Streptococcus pneumoniae. C) Streptococcus mutans. D) Enterococcus. E) Mycoplasma pneumoniae. 11) Which of the following streptococci is associated with dental caries? A) viridans streptococci B) Streptococcus pyogenes C) Streptococcus pneumoniae D) Streptococcus equisimilis E) Streptococcus arginosus 12) Anthrax, which means "charcoal" in Greek, derives its name from _____ A) the airborne endospores it produces. B) the staining properties of the bacillus under the microscope. C) the black eschars it produces on human skin. D) its ability to invade the bloodstream and produce toxemia. E) the high mortality it causes in infected individuals. 13) Which of the following bacteria produce one of the most deadly bacterial toxins known? A) Clostridium perfringens C) Clostridium tetani B) Clostridium difficile D) Clostridium botulinum E) Corynebacterium species 14) Which of the following bacteria can cause life-threatening pseudomembranous colitis? A) Clostridium difficile B) Staphylococcus aureus C) Streptococcus pyogenes D) Enterococcus species E) Clostridium botulinum 15) How does the toxin from Clostridium tetani produce its action? A) It fuses irreversibly to neuronal cytoplasmic membranes, blocking release of acetylcholine at synaptic clefts. B) The smaller polypeptide of its toxin can block the release of inhibitory neurotransmitters by inhibitory neurons in the central nervous system, causing simultaneous contraction of both muscles in an antagonistic pair. C) It is a pyrogenic toxin, which triggers a diffused rash and, later, sloughing of skin. D) It destroys tissues, including muscle and fat. E) It produces antibodies that attack the neuromuscular junctions in skeletal muscle and prevent them from relaxing. 16) Listeria virulence is directly related to its ability to ______ A) produce powerful toxins. B) form very resistant endospores. C) live within cells and thus avoid exposure to the immune system of its host. D) easily become a pathogen in humans. E) resist most antimicrobial agents. 17) The pus from an abscess in a patient's jaw contains microbes that form yellowish grainy masses and appear filamentous under the microscope. Neither antifungal medication nor a normal course of antibiotics has been effective in treating the infection. The abscess is likely the result of infection with A) Actinomyces. B) Mycobacterium. C) Nocardia. D) Propionibacterium. E) Streptococcus. 18) What is the most common disease caused by Propionibacterium? A) acne B) food poisoning C) pneumonitis D) folliculitis 19) Streptococcus pneumoniae is a leading cause of ______ A) acne. C) pharyngitis B) furuncles. D) primary atypical pneumonia. E) otitis media. 20) The soil bacterium Nocardia asteroides can establish opportunistic infections of the _____ A) skin C) central nervous system B) lungs D) cardiovascular system. E) skin, lungs, and central nervous system

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1)Mechanims by which antibiotics kill or inhibit microbialgrowth are: a) Inhibition of cell wall synthesis b) Injury of cellmembrane c) Inhibition of protein synthesis d) Inhibition of DNA orRNA synthesis e) All of the above

2)The semisynthetic methicillin has the advantage of: a) Beingbroad spectrum b) Being inactivated by penicillanse only onprolonged usage c) Not being affected by penicillinase d) All ofthe above e) None of the above

3)Which of the following interfere with cell wall synthesis? a)Chloramphenicol b) Tetracyclines c) Penicillin d) Bacitracin e)Only C and D above

4)A rare but serious complication of chloramphenicol treatmentis: a) Kidney damage b) deafness due to damage of eight cranialnerve c) Anemia due to suppression of bone marrow cells d0 Anemiadue to destruction of circulationg red blood cells e) None of theabove

5)The development of drug resistance in a microorganism may bedue to: a) Abilty of the organism to destroy the abtibioticb)mutation that allows the organism to by-pass the sensitive stepc)Sporulation d)All of the above e) Only A and B above

6)The synthesis of vitamins B and K by enteric bacteria providesan example: a) Commensalism b) Symbiosis c) Opportunism d)Infection e) synegestic effect

7)The normal habotat of Staphylococcus aureus may be: a) Urinarytract b) stomach c) Healthy tissues d) nose, throat, and skin e)Scalp

8)Clostridium perfringens may be found as a part of the normalflora in: a) Mouth b) Intestines c) Lungs d) Urinary tract e)Wounds

9)A disease constantly present in a locality is said to be: a)Endemic b) Epidemic c) Pandemic d) Sporadic e) Reservoir

10)Foreign substances that induce a specific immune responseafter gaining entrance to the body are termed: a) Antigens b)Antibodies c) Cytolysins d) Complement e) None o the above

11)Essential prperties of an antigen are: a) It must be foreignto the host b) It must be degradable by the host c) It must be alarge molecule and possess at least two different determinantgroups d) It must posses a three-dimentional or tertiary structuree) All of the above

12)Based on antigenic differences inH chains, antibodies havebeen divided into the following classes: a) IgG and Iga b) IgM andIgD c0 Ige d) all of the above e)None of the above

13)quantitatively the largest class of immunoglobulins in humanserum is: a) IgG b) IgA c) IgM d) IgD e)IgE

14)Which of the following statements are applicable to IgMimmunoglobulins: a) They are the antibodies first to be detectedafter injection of an antigen b) In the presence of complement,they are highly lethal to gram-negative bacteria c) They play animportantnprotective role during the early stags of infection d)All of the above e) None of the above

15)Antibodies are chiefly produced by: a) Lymphocytes b)Eosinophilis c) Erythrocutes d) Polymorphonuclear neutrophils e)None of the above

16)Today antiserum is mainly used for: a) Temporary preventionof certain viral infections b) Neutralization of certain potentbacterial toxins c) Treatment of hepatitis patients d) Only A and Babove e) None of the above

17)antiserum may be described as: a) Blood serum that containsantibodies b) Blood serum that contains antigens c) Blood serumthat contain an antibiotic d) Bovine blood serum prior to injectionof an antigen e) None of the above

18)The sources of antiserum are: a) Chemical synthesis in thelaboratory b) Blood from animal that has developed antibodies to aspecific antigen c) Gamma globulin separatd from pooled human bloodd) All of the above e) Only B and C above

19)The major advantage of antiserum is: a) It is quickly andeasily produced b)It provides circulationg antibodies immediatelyc) It can be administered orally d) All of the above e) none of theabove

20) A viral vaccine for the common cold probably would not bebeneficial because: a) A pure culture cannot be frown in tissuecultures b) A multiplicity of viral agents is responsible for thecoomon cold c) Immunity is of brief duration d) All of the above e)None of the above

rosewolf780

Class 6: Viruses (and Cells, continued)

Making connections: viruses and microbes Match the cell biology concept (on page 1) with an important application of that concept (on page 2). Then answer the follow-up questions at the bottom of page 2.

Cell Biology concepts
1. Bacteria that cannot construct new cell wall material become fragile and break down.
2. During influenza infection, the viral enzyme neuraminidase is required to release new viruses from the host cell in which they were made. Once released, the new viruses can infect many additional cells.
3. Thermus aquaticus is a bacterium found in hot springs and can live at temperatures up to ~80Â°C (175Â°F). It has adapted so that its enzymes are most functional at the elevated temperatures, compared with many organismsâ enzymes that function best ~37Â°C (98Â°F).
4. Until the isolation and investigation of retroviruses, scientists thought that RNA could be copied from DNA, but DNA could not be copied from RNA. Research on this class of viruses led to an update to this âCentral Dogmaâ of biology.
5. Some bacteria have adapted, so that the enzymes involved in making cell wall materials have a slightly different shape and can no longer be bound by certain drugs.
6. Rhizobia are bacteria that colonize the roots of certain plants (legumes, including beans and peas). The host plant benefits from the prokaryotesâ ability to âfixâ nitrogen, converting N2 from the atmosphere into a form that is usable by the plant.
7. Many species of bacteria contain the enzyme cellulase. More than 10 billion such bacteria and other symbiotic microbes may be found in a single milliliter of material from inside the digestive system of ruminant mammals.
8. Fungi, including those that cause athleteâs foot, use ergosterol to maintain healthy membranes. Animal cells do not make ergosterol, they use a similar lipid â cholesterol.
9. During retrovirus infection, a DNA copy is made of the virusâs RNA genome. A cut is made in the host cellâs DNA and the DNA copy of the viral genome is pasted into the host chromosome by a viral enzyme called integrase.
10. Prokaryotic cells contain smaller ribosomes (â70Sâ ribosomes) than eukaryotic cells (â80Sâ ribosomes). Both types of ribosomes synthesize proteins, but the macromolecules they use to do it are somewhat different.

2
Applications
_______ Oseltamivir, also called Tamiflu, binds and inhibits the viral protein neuraminidase.
_______ Clotrimazole is a drug that is used to treat certain infections. It interferes with synthesis of ergosterol, a lipid involved in phospholipid membranes.
_______ Penicillin is a drug that interferes with synthesis of peptidoglycans (these are biological molecules that are part protein and part carbohydrate) that are present in certain cell walls.
_______ HIV is often treated with several drugs that inhibit different parts of the viral replicative cycle. Raltegravir is an example of a drug that interferes with the integration of viral genes into the host cellâs chromosome.
_______ Cows, like other vertebrates, lack the ability to breakdown cellulose. Yet they are able to live on a diet of grass and other vegetation high in cellulose.
_______ Enzymes isolated from extremophiles have been very useful in laboratory research. For example, Taq polymerase facilitates PCR, a revolutionary technique for production of DNAs of particular sequences, which requires cycling reactions through high temperatures.
_______ Plants and animals require nitrogen to make biological macromolecules, however theyâre unable to convert atmospheric nitrogen (N2) into a biologically useful form.
_______ Azithromycin is a drug that binds to 70S ribosomes and blocks synthesis of any new proteins.
_______ Methicillin-Resistant Staphylococcus aureus (MRSA) can cause life-threatening infections of the skin and bloodstream. One of the reasons MRSA infections are so serious is that they are resistant to treatment by many antibiotics, including methicillin and penicillin.
_______ The enzyme reverse transcriptase, isolated from retroviruses, is an important tool in molecular biology research. Scientists interested in learning what genes are turned on in particular cells use it to make DNA copies of RNAs they are studying (The DNA copies are useful because they are more stable).

When you have completed the matching activity, answer these follow-up questions:
â¢ What types of infections can be treated with the following drugs?
o Penicillin
o Clotrimazole
o Azithromycin
o Tamiflu
o Raltegravir
â¢ Why are these drugs (above) safe for you to take? That is, why donât they kill your cells?
â¢ Cancer cells are your own human cells that have become deregulated so that they divide and pile up in an uncontrolled way. Many chemotherapy drugs treat cancer by interfering with cell division and other cell processes.
o Why are there so many more side effects for individuals undergoing chemotherapy than for individuals taking antibiotics?

Microbiology and Immunology 4100A Lecture Notes - Lecture 16: Cytotoxicity, Enterotoxin, Exotoxin

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