Review of Basic Clinical Microbiology

Question 1

What are the benefits associated with microorganisms in pharmacy?

Answer 1

• MFR of: antibiotics, steroids, therapeutic enzymes, polysaccharides, recombinant DNA technology products (like insulin)
• Production of vaccines
• Determination of antibiotic, vitamin, and aa concentration
• Detection of mutagenic or carcinogenic activity

Question 2

What are the problems associated with microorganisms in pharmacy?

Answer 2

• Contamination of non-sterile and sterile medicines with a risk of infection and/or product deterioration
• Etiological agents of infectious diseases and other diseases (microbes can be reservoirs of antibiotic resistance)
• Cause of pyrogenic reactions (fever) when introduced into the body even in the absence of infection
• Reservoir of antibiotic resistant genes

Question 3

Virus, viroids, prions, bacteria, fungi, and protozoa comparison: What are the smallest?

Answer 3

Viroids are the smallest. They are only 120-475 nucleotides long.

Question 4

Virus, viroids, prions, bacteria, fungi, and protozoa comparison: Which lack nucleic acids?

Answer 4

Prions - they are just proteins, derived from host glycoproteins. Mis-folded proteins that replicate slowly by splitting into infectious polymers capable of further lengthening. Length is

Question 5

Virus, viroids, prions, bacteria, fungi, and protozoa comparison: Which is only made up of RNA?

Answer 5

Viroids are only made up of RNA.

Question 6

Virus, viroids, prions, bacteria, fungi, and protozoa comparison: Which can be made of DNA or RNA, that could be ds, ss, circular, or linear in nature?

Answer 6

Viruses. They are generally the largest (20-400nm in length).

Question 7

What do viruses, viroids, and prions have in common?

Answer 7

They cannot replicate and metabolize unless they infect a host cell.

Question 8

What can viruses infect?

Answer 8

Plants, animals, humans, and even bacteriophages.

Question 9

Name the virus:

1. What contains a capsomere with RNA?
2. What contains a capsid built of glycoproteins in a spherical shape?
3. What has RNA, a membranous envelope, and glycoproteins?
4. What is the mosquito-like guy with DNA?

Answer 9

1. Tobacco mosaic virus
2. Adenoviruses
3. Influenza viruses
4. Bacteriophage

Question 10

What do measles, arbovirus, rabies, Hepatitis A, B, & E, varicella zoster, smallpox, HPV, Rubella, measles, and polio have in common?

Answer 10

They are all viruses causing disease that are vaccine-preventable.

Question 11

Virus, viroids, prions, bacteria, fungi, and protozoa comparison: Which can be gram(+) or gram (-)?

Answer 11

Bacteria

Question 12

How are bacteria classified?

Answer 12

By shape (cocci, spiral, bacilli), gram reaction, atmosphere (obligate/micro/facultative aerobes/anaerobes), spores (endospore) and genetic classification (reactions needed for species id).

Question 13

What is a facultative anaerobe?

Answer 13

A bacteria that can make ATP through aerobic respiration if oxygen is present, but can switch to fermentation or anaerobic respiration if oxygen is absent.

Question 14

In bacteria, there are multiple ways of classifying, including phenotypically, analytically, and genotypically. With gram-staining, which bacteria will retain the crystal violet color (used before the safranin red) and why?

Answer 14

The gram-positive will retain the crystal violet color, while the gram-negative will be colored red by the safranin. This is because the gram-positive bacteria have a more penetrable cell wall, and so the crystal violet penetrates and stays in the cell, and does not get completely washed away by the decolorizer. Compare that to the gram-negative bacteria, which has an impenetrable cell wall that does not allow the crystal violet into the cell. Therefore, it is washed away when the decolorized is added.

Question 15

Virus, viroids, prions, bacteria, fungi, and protozoa comparison: What makes fungi distinct from plants and animals?

Answer 15

They are eukaryotes like us (rather than prokaryotic like bacteria), but they can be multinucleate or multicellular. They have a thick cell wall with chitin, and have a 70S ribosome vs an 80S like us.

Question 16

Virus, viroids, prions, bacteria, fungi, and protozoa comparison: Which has the ability to transform from filamentous moulds to unicellular yeasts as a virulence mechanism? How does temperature play a role?

Answer 16

Fungi. They form hyphae at lower temperatures, and form yeasts at higher temperatures (such as in a host).

Question 17

Virus, viroids, prions, bacteria, fungi, and protozoa comparison: Which is a one-celled animal found in most habitats?

Answer 17

Protozoa.

Question 18

Virus, viroids, prions, bacteria, fungi, and protozoa comparison: What agent causes malaria and traveler’s disease as well as toxoplasmosis?

Answer 18

Protozoa.

Question 19

In protozoa, what are sporozoa, flagellates, amoebae, and ciliates?

Answer 19

This refers to where they dwell and how they move. Sporozoa are intracellular parasites, flagellates move by beating one or more flagella, amoebae move by extending pseudopodia without a fixed shape, and ciliates move by beating many cilia.

Question 20

What feature does the bacteria Clostridium have?

Answer 20

Endospore.

Question 21

What has a thick peptidoglycan layer?

Answer 21

Gram-positive bacteria.

Question 22

What is the purpose of a laboratory diagnostic test, and what are the characteristics of a useful test?

Answer 22

It can be used to demonstrate the presence or absence of a current or past infection (by detecting antibodies).
Characteristics of a useful test would be accurate methods, simple, and affordable for the intended population.

Question 23

What are the uses of laboratory diagnostic tests?

Answer 23

Patient management when the symptoms don’t point towards a particular diagnosis, screening for asymptomatic infections, surveillance, epidemiological studies, effectiveness of intervention evaluation, and detection of infections with drug-resistant markers.

Question 24

Diagnosis: What is microscopy, subculture, and sensitivity testing?

Answer 24

Microscopy: Staining, such as gram-staining
Subculture: Have to use very rich media to identify pure growth from single pure colony using biological tests.
Sensitivities: Use discs to diffuse compounds to see what halts spread of colonies. Can see resistance.

Question 25

What are the benefits of serodiagnosis and DNA technologies?

Answer 25

They are faster and cheaper than microscopy, subculture, and sensitivity tests. (They are also useful for diagnosing meningitis).

Question 26

What is easier to use for measuring antibodies in serum or secretions, direct or indirect methods?

Answer 26

Indirect methods are easier to use, but are less accurate than the direct methods. For example, ID based on genome detection has a higher confidence level compared to serology IgG, which is easier to use.

Question 27

Terms to know: Process of removing microorganisms from the surface.

Answer 27

Disinfection

Question 28

Terms to know: Use of preservatives to prevent microbial spoilage of the product, cannot be toxic.

Answer 28

Preservation

Question 29

Terms to know: Destruction or inhibition of microorganisms on living tissues to limit infection

Answer 29

Antisepsis

Question 30

Terms to know: Must not be toxic or irritating for these tissues; to reduce microbial population.

Answer 30

Antiseptics

Question 31

Terms to know: Any process that eliminates (removes) or kills all forms of life

Answer 31

Sterilization

Question 32

What temperature is needed to kill spores?

Answer 32

121 C or 250F

Question 33

What are some examples of physical sterilization? Chemical?

Answer 33

Physical sterilization: Dry or moist heat, radiation, filtration.
Chemical sterilization: Liquid or gaseous sterilization (alcohol, aldehydes, formaldehyde)

Question 34

What method of sterilization uses a vacuum and a filter? What size of particle is caught with the filter?

Answer 34

Filtration, collects particles that are at least 0.22um in size.

Question 35

What is MBC? MIC?

Answer 35

MBC is minimal bactericidal concentration - lowest concentration needed to prevent growth by KILLING.
MIC is minimal inhibitory concentration - lowest concentration of a compound which will inhibit visible growth.

Question 36

Looking at inhibitory and lethal antibiotics, how would the concentration of a bacteria over time be affected by each?

Answer 36

The CFU’s of a bacteria exposed to a static agent would remain steady (preventing further growth), while the CFU’s of a bacteria exposed to a cidal agent would dramatically drop over time.

Question 37

Looking at a broth dilution method culture, how would you determine the MIC?

Answer 37

You would set up a row of broths with the same bacteria cultured in each one. The antibiotic would be diluted to appropriate concentrations, and added to the broths. The lower concentrations would not inhibit the growth, but there would be a point where it would inhibit the growth, which would be the MIC.

Question 38

What is the most common antibiotic producer?

Answer 38

Streptomyces sp.

Question 39

What type of bacteria produce dextran?

Answer 39

lactic acid bacteria

Question 40

What are phages beneficial in?

Answer 40

They can infect bacteria, and can be genetically engineered so that different peptides can be displayed. Can attach different peptides from libraries at random, and see which attach to the specific target. Then can amplify.

Question 41

What are the principle of the Ames test?

Answer 41

It can help to screen a variety of chemicals for potential carcinogenicity, or for potential as anti-cancer compounds. A large number of compounds can be screened by their ability to induce mutagenesis in a specially constructed mutant derived from salmonella that requires histidine.
A high number of revertants (that no longer require histidine) suggest that the mutagen causes mutations.