MED MICRO: Quiz 4

Compare and contrast the pathogenicity of Clostridium botulinum and Clostridium tetani, including mechanisms of action of their toxins and disease manifestations.

Clostridium botulinum is a pathogen that causes botulism, and Clostridium tetani is the pathogen that causes tetanus. Both bacteria are anaerobes that get introduced as endospores. The botulism toxin can work as an antidote for the tetanus toxin, but the tetanus toxin cannot work in the same way for botulism. The botulism toxin works to inhibit the neurotransmitter acetylcholine and cause flaccid paralysis, and the tetanus toxin blocks the release of inhibitory neurotransmitter, causing muscles to contract spasmodically, and sometimes lock in continuous contraction, resulting in non-flaccid paralysis. Therefore, the tetanus toxin cannot counter flaccid paralysis and cannot be used as an antidote.

T/F: The resident microbiota have no role in defense against pathogen invasion.

False

T/F: Clostridium perfringens is the most common cause of necrotizing fasciitis.

False C. perfringens causes gas gangrene. Necrotizing fasciitis is caused by Streptococcus pyogenes

T/F: TCRs only recognize antigens presented on MHCII molecules by antigen-presenting cells like dendritic cells.

False TCRs only recognize antigens on MHCI molecules

T/F: Because they are common soil saprobes, dermatophytes are fungi that are not contagious in humans.

False dermatophytes cause many infections in humans

Both necrotizing fasciitis and gas gangrene are diseases characterized by rapid, spreading tissue necrosis. Compare and contrast the infectious agents, the pathology and treatment.

Necrotizing fasciitis is a disease caused by the pathogen Streptococcus pyogenes. This is a very harmful bacteria because it lets off enzymes that cause it to enter the body and destroy tissues. It can break down blood clots, DNA, and hyaluronic acid between cells. This bacteria secretes many toxins in order to destroy these tissues. The toxins Streptococcus pyogenes secretes are known as M protein, Streptolysin S, and Endotoxin A. M protein is used most commonly to avoid phagocytosis by binding to mucosal membranes. Streptolysin S is used to kill erythrocytes and other bodily cells. Endotoxin A works to overstimulate the immune system to damage the tissue and cause inflammation. The only known treatments for necrotizing fasciitis include complete removal of the infected tissue from the body or antimicrobial medication. Gas gangrene is caused by a Gram-positive bacterium known as C. perfringes. This bacteria is able to form endospores which causes it to spread more quickly without dying. Gangrene does not usually infect healthy tissue, but it invades dead tissue and releases toxins that kill neighboring cells. Treatment includes removal of dead tissue, penicillin, and antitoxin injections.

The Gram-negative diplococcus ________ is resistant to phagocytosis and releases Lipid A to cause inflammation.

Neisseria meningitidis This cocci causes bacterial meningitis

Mucous membranes are quite thin and fragile. How can such delicate tissue provide defense against microbial invaders? - The mucus is a physical trap that contains a variety of antimicrobial chemicals. - Both the mucus and the outer layer of cells are shed frequently. - The mucus physically traps microbes, contains a variety of antimicrobial chemicals, and is shed constantly, along with the outermost layer of cells. - The mucus secreted by the mucous membrane physically traps microbes. - The mucus contains a variety of antimicrobial chemicals and molecules.

The mucus physically traps microbes, contains a variety of antimicrobial chemicals, and is shed constantly, along with the outermost layer of cells.

Adaptive immunity is sometimes also called acquired immunity. Which of the following statements provides a basis for the alternative name? - Lymphocytes of the adaptive immune system are highly specific for a single antigenic determinant. - To become activated, lymphocytes require exposure to the antigenic determinant for which they are specific. - Activated lymphocytes may persist for years in the body. - Activated lymphocytes produce daughter cells that are identical in specificity and function. - Lymphocytes reactive to normal body components are removed.

To become activated, lymphocytes require exposure to the antigenic determinant for which they are specific.

T/F: The growth of some microbes is inhibited by elevated body temperature.

True

A person licks a needle before injecting a drug into a vein. The person later develops a bacterial infection of the blood. This is an example of: - microbial synergism. - a disruption of the normal microbial population of the blood. - microbial antagonism. - immune suppression leading to disease. - a member of the microbiota gaining access to an unusual location in the body.

a member of the microbiota gaining access to an unusual location in the body.

African sleeping sickness is fatal if not treated because the parasite: - produces a non-immunogenic toxin the immune system cannot neutralize. - evades destruction by the immune system by changing surface antigens. - is an intracellular parasite in RBC's, where they are not detected by the immune system. - reproduces so fast there is no time for an immune response to develop. - produces a toxin which binds irreversibly to neurons.

evades destruction by the immune system by changing surface antigens This disease is caused by the protozoan Trypanosoma brucei

The production of __________ enzyme breaks down connections between cells, allowing Streptococcus pyogenes to invade tissue and cause necrotizing fasciitis.

hyaluronidase S. pyogenes also causes impetigo

The process known as _____________ brings a variety of physical, chemical, and cellular factors together to fight invading microorganisms

inflammation

Listeria monocytogenes pathogenesis is directly related to its ability to: - produce a powerful toxin. - resist most antimicrobial agents. - produce a polysaccharide capsule. - form endospores. - live and reproduce inside its host's cells.

live and reproduce inside it's host cells causes bacterial meningitis

Infection known as ________ frequently begins as an injury that rapidly becomes red, swollen, hot to the touch, and intensely painful.

necrotizing fasciitis

Spongiform encephalopathy diseases develop as a result of infection with __________

prions (vCJD)

An arachnid parasite causes the skin disease known as __________.

scabies

A strain of Neisseria gonorrhea has a mutation which has caused it to lose the ability to produce fimbriae and become less virulent as a consequence. What function has this pathogen lost? - the ability to adhere to cells of the body - the ability to prevent phagocytes killing it - the ability to establish a latent infection - the ability to move from one location in the body to another - the ability to produce an endotoxin

the ability to adhere to cells of the body Cells of Neisseria all have fimbriae, capsules, and lipooligosaccharides. If they lack any of these features they become avirulent.

One of the advantages of adaptive immunity over innate immunity is: - the ability to recognize antigens common to many microbes. - the response targets classes of pathogen instead of specific pathogens. - the response is far faster. - the response is targeted against a single pathogen.

the response is targeted against a single pathogen.

The degree to which a microbe is able to cause disease is known as its __________.

virulence

1. Botulism are produced by what pathogen? 2. What type of pathogen (ex: Bacteria, Virus, Fungi, Protozoa) produces botulism?

1. Clostridium botulinum 2. Bacteria

1. Gangrene are produced by what pathogen? 2. What type of pathogen (ex: Bacteria, Virus, Fungi, Protozoa) produces gangrene?

1. Clostridium perfringes 2. Bacteria

1. Leprosy are produced by what pathogen? 2. What type of pathogen (ex: Bacteria, Virus, Fungi, Protozoa) produces leprosy?

1. Mycobacterium leprae 2. Bacteria

1. Warts are produced by what pathogen? 2. What type of pathogen (ex: Bacteria, Virus, Fungi, Protozoa) produces warts?

1. Papillomavirus 2. Virus

1. Shingles are produced by what pathogen? 2. What type of pathogen (ex: Bacteria, Virus, Fungi, Protozoa) produces shingles?

1. VZV (varicella-zoster virus) 2. Virus

"Ringworm" is caused by - dermatophytes growing in the upper dead tissue layers of the skin. - a hypersensitivity reaction caused by superficial contact with dermatophytes. - parasitic worms that infect the skin. - dermatophytes infection that has become systemic. - immunosuppression due to HIV infection.

dermatophytes growing in the upper dead tissue layers of the skin