Micro- Exam 4 Quizzes

Evaluate the statements below and assess which are correct regarding an opportunistic infection by Clostridium difficile.

- When an individual is subject to antibiotic chemotherapy, the normal flora of the gut are killed or inhibited but C. dificle can multiply, produce spores and sporulate - C. dificile is anaerobic spore-forming organisms that may be found in the normal flora of the gut and is often an inhabitant of health care facilities - An overabundance of C. dificile in the gut leads to toxic megacolon, water diarrhea and pseudomembrane colitis - C. dificile produces three toxins coded for by genes in the patogenicity locus; binary toxin (which alters the cytoskeleton), enterotoxin and cytotoxin (which can cause inflammation and diarrhea)

Infectious disease frequency is an important parameter for epidemiologists. In order to measure infectious disease frequency several measurements are needed, such as ______. (Check all that apply.)

- accurate count of total population - population exposed to infectious disease - number of people affected with infectious disease

Possible symptoms of toxic shock syndrome include ______.

- fever - diarrhea - nausea and vomiting - shock

What are the virulence factors that Bacillus anthracis uses to avoid host defenses?

- production of an exotoxin - production of a capsule that inhibits phagocytosis

Place the events that occur in the pathogenesis of Escherichia coli gastroenteritis in the correct order.

1. E. coli enters the body by fecal-oral transmission 2. Some E.coli strains colonize the small intestine and produce watery diarrhea 3. Some strains of E. coli can invade the large intestine and cause dysentery 4. Some E. coli strains produce Shiga toxin which is absorbed by the bloodstream and causes hemolytic-uremic syndrome 5. E. coli exits the body with feces

Use the phrases provided to describe the distinctive characteristics of streptococcal pharyngitis.

1. S. pyogenes enters via ingestion or inhalation 2. Pharyngitis, fever, enlarged lymph nodes; sometimes tonsililitis abcess; scarlet fever with strains that produce erythrogenic toxin symptoms go away. 3. S. pyogenes exits via the nose and mouth 4. Glomerulonephritis can occur 5. Rheumatic fever can occur 6. Neurological abnoralitescan occur complications subside 7. Damaged heart valves leak, heart failture develops

Drag the labels to their corresponding mechanism of transmission.

Airborne transmission: coughing, sneezing, droplet nuclei, dust Contact transmission: kissing, sex, touching Vehicle transmission: surgical instruments, fomites, shared cups Vector-borne transmission: anthropods, animals, fleas, mosquitoes, ticks

Label the figure showing the action of A-B toxins.`

B subunit binds to a specific receptor on the host cell --> toxin is taken up by endocytosis --> toxin subunits separate allowing the A subunit to enter the cytoplasm

Assess the following words/statements and classify them according to whether they refer to cationic peptides or bacteriocins.

Cationic peptides: histatin, cathelicidin, defensins Bacteriocins: toxic chemicals produced by the normal microbiota, colicins, lantibiotics

A patient exhibiting septic shock could be infected with all of the following EXCEPT ______.

Clostridium

Drag the statements to the term they describe in order to review characteristics of virulence factors.

Coagulase: causes red blood cells to clot Collagenase: breaks down framework proteins in skin and connective tissue Elastase: degrades laminin in basement membranes Hemolysins: kill red blood cells Hyaluronidase: breaks down extracellular matrix holding tissues together Phospholipase: degrades components of the plasma membrane Leukocidins: kill white blood cells Pyrogenic toxin B: protease from group A streptococci Streptokinase: leads to degradation of fibrin clots

This type of Escherichia coli infection causes the formation of effacing lesions.

EPEC

Choose which of the following characteristics describe endotoxins versus exotoxins.

Endotoxins: lipopolysaccharide, lipid A, gram-negative infections, produce fever, heat stable, weakly immunogenic, cell wall material, can cause septic shock, usually on chromosomal genes Exotoxins: protein, no fever, carried on plasmids, excreted by living cells, heat liable, highly toxic, antigenic

Epidemiology plays an important role in studying and preventing the spread of infectious disease in populations. Determine the correct term to successfully complete each sentence regarding the spread of infectious disease within populations.

Epidemiologists are interested in how infectious diseases spread within populations, especially those diseases that are communicable , meaning, spread easily from person to person. A disease is considered endemic if it is constantly present at low levels within a population. If sudden increases in disease occurrence occur worldwide, this may indicate the development of a pandemic. Alternatively, if such increases occur only within a given population, this may indicate that there is an epidemic at hand. If an epidemic arises from a communicable disease, then it is considered a propagated epidemic where there is a slow rise in the number of cases. In contrast, if an epidemic arises from a noncommunicable disease, then it is considered a common-source epidemic and there is a rapid rise in the number of cases. To understand the nature of these epidemics and how they occur, one must understand how the effects of major genetic change to the pathogen, called antigenic shift, differs from the effects of minor genetic change to the pathogen, called antigenic drift

Compare and contrast exotoxins and endotoxins by placing each attribute under the correct category.

Exotoxins: cytoplasmic protein; may or may not be secreted (location), gram-positive and gram-negative bacteria (source), protein (structure), easily heat inactivated, generally very toxic Endotoxins: part of the outer membrane of gram-negative bacteria (location), only gram-negative bacteria (source), LPS specifically lipid A (structure), fairly heat stable. small localized amounts tend not to cause problems, very toxic once it becomes systemic

A person unable to make lysozyme in their tears would be more susceptible to infection by ___________.

Gram-positive bacteria

Please choose the statement that best describes Staphylococcal Scalded Skin Syndrome (SSSS).

It is an exotoxin-mediated disease that can be compared to a systemic form of impetigo.

Why are pathogens that are transmitted person-to-person often less virulent than those transmitted by arthropod vectors?

Person-to-person transmission requires the infected host to remain alive long enough to transmit the organism to another susceptible host.

There are three types of control measures used by scientists to prevent and control epidemics. Categorize each action into the appropriate type of control measure.

Reduce or eliminate the source or reservoir of infection: quarantine of carriers, wastewater treatment, use of antimicrobial drugs Break connection between source of infection and those susceptible: pasteurization, insecticides, drinking water chlorination, mandatory hand washing by food handlers Reduce number of susceptible individuals and raise herd immunity: active immunization, passive immunization, prophylactic treatment

Drag the labels to complete each of the sentences that describes the progression Streptococcal pneumonia.

Streptococcus pneumoniae are normal bacterial inhabitants of the upper respiratory tract, and are prevented from causing disease by microbial antagonism; competition for nutrients and space by the other flora. S. pneumoniae is surrounded by a hylauronic acid capsule, which helps the cell avoid phagocytosis, and if the host is immunocompromised, the bacteria can proliferate in the alveoli causing inflammation. In addition to the polysaccharide capsule, S. pneumoniae produce pneumolysin, a toxin that destroys the host cells causing the alveoli to fill with blood and fluid. The alveoli become inflamed and the patient often coughs up blood along with additional symptoms such as chills, labored breathing and chest pain. Unfortunately many strains of S. pneumoniae are resistant to macrolide and β-lactam antibiotics

The difference between toll-like receptors (TLRs) and NOD-like receptors (NLRs) is that

TLRs are transmembrane receptors, whereas NLRs are located in the cytosol.

The presence of a granuloma is an indication of __________.

chronic inflammation

Label the figure to better understand epidemic curves then match the correct example for each epidemic curve.

common-source epidemic --> food poisoning Propagated epidemic --> strep throat

A lysosome

contains lysozyme and proteases that digest bacteria.

Both Escherichia coli and Neisseria gonorrheae adhere to urethral epithelia using ______.

fimbriae

Initial attachment of microorganisms often involves ______.

flagella and is reversible

A person lacking paneth cells would be more likely to get an infection of their ___________.

gastrointestinal tract

Brian lives in a town where 98% of the population is immunized against measles. Brian is unlikely to get measles, despite the fact that he has never been immunized. This situation demonstrates the concept of ______.

herd immunity

Digestion of a pathogen within a phagolysosome involves all of the following EXCEPT

high pH in the phagolysosome that denatures pathogen proteins.

During 2007, there were 3.6 new cases of pertussis per 100,000 susceptible individuals in the United States, part of a steady increase that has been occurring since the 1980s. This statistic illustrates the term ______.

incidence

Label the stages that characterize progression of infectious disease.

incubation period --> prodromal stage --> illness --> covalenscent period

Phagocytes are attracted by all of the following EXCEPT

lysosomes.

Match the term with applied math to better understand how those words are used in epidemiology.

morbidity = # of new cases during specific time/# of individuals in pop Prevalence = total # of cases in pop/total pop x100 Mortality = # of deaths/size of total pop with same disease

The ID50 refers to the

number of organisms in the initial inoculum required to cause infection in 50% of hosts.

Leukocytes detect the presence of pathogens by looking for __________.

pathogen-associated molecular patterns (PAMPs)

The total number of individuals infected in a population at any one time is referred to as ______.

prevalence rate

Assess the following statements and determine whether they refer to stage 1, 2, or 3 of Lyme disease progression.

stage 1: Erythema migrans may develop at the site of the tick bite, followed by flu-like symptoms, malaise, fever, headache and fatigue stage 2: the organisms disseminates which leads to heart inflammation, neurological issues, and arthitis in the major joints stage 3: Neuron demyelination may occur resulting in Alzheimers-like symptoms and manifestations resembling multiple sclerosis

If a host was unable to make interferon, it would make them more susceptible to infection by _____________.

viruses

Clostridium difficile is allowed to overgrow in the intestines when competing organisms are killed by antibiotics. Check all of the conditions that apply to antibiotic-associated colitis.

watery diarrhea pseudomembrane intestinal obstruction toxic megacolon rash (?) bloody diarrhea (?)