Bacteriology

Question 1

What three groups of molecules are found in cytoplasm?

Answer 1

1. ) Macromolecules - proteins (enzymes), mRNA, tRNA
2. ) Small molecues - energy sources, precursors of macromolecules, metabolites or vitamins
3. ) inorganic ions - such as co-factors.

Question 2

what is included in the protein component of the bacterial chromosome (nucleoid)?

Answer 2

1. ) Transcription Factors - regulate bacterial genome.

2. ) Nucleoid-associated proteins (NAPs) - carry out the dynamic spatial organization of the nucleic acid.

Question 3

All bacteria cytoplasmic membrane is composed of ___ & ____? What is the difference with regards to mycoplasmas?

Answer 3

Phospholipid bilayer and proteins. Sterols are only present in mycoplasmas

Question 4

Where does bacterial respiration occur?

Answer 4

Across the cytoplasmic membrane.

Question 5

What types of substances can pass a phospholipid bilayer via passive diffusion?

Answer 5

small lipid-soluble compounds

Question 6

What is peptidoglycan and where is it found?

Answer 6

Peptidoglycan is a polymer of disaccharides cross-linked by short chains of amino acids (peptides). It is found in the cell envelope of bacteria.

Question 7

What is unique about the cell wall of gram-positive bacteria?

Answer 7

Thick layer of murein (aka: peptidoglycan) and techoic acids.

Question 8

What is the function of techoic acids found in the cell wall of ____ bacteria?

Answer 8

provides rigidity in gram positive bacteria.

Question 9

What is unique about gram-negative bacteria cell envelope?

Answer 9

Composed of a thin layer of murein/peptidoglycan surrounded by an outer membrane.

Question 10

What are the components of the outer membrane of gram-negative bacteria cell wall?

Answer 10

Lipopolysaccharides (LPS or endotoxins) and porins.

Question 11

What are porins and where are they found?

Answer 11

Porins are proteins allowing diffusion of hydrophilic molecules into the periplasmic space of gram-negative bacteria. They are found in the cell envelope of gram-negative bacteria.

Question 12

What is periplasmic space?

Answer 12

The space between the cell envelope and cytoplasmic membrane of bacteria.

Question 13

What is the function of the capsule (AKA: glycocalyx) in bacteria?

Answer 13

Mediates attachment to particular surfaces and protects bacteria from engulfment.

Question 14

Fimbriae

Answer 14

Shorter and stiffer than flagella and are usually involved in adherence to surfaces.

Question 15

Monotrichous

Answer 15

Flagellar arrangement in which one flagella is present

Question 16

Lophotrichous

Answer 16

Flagellar arrangement in which multiple flagella are present originating from one area of the cell wall

Question 17

Peritrichous

Answer 17

Flagellar arrangement in which multiple flagella are arising from multiple areas around the periphery of the cell wall.

Question 18

Amphitrichous

Answer 18

Flagellar arrangement in which one flagella arises from each pole.

Question 19

Germination

Answer 19

The reverse of sporulation.

Question 20

What are the main genera of spore-forming bacteria?

Answer 20

Bacillus and Clostridium

Question 21

In what group relative to oxygen requirement for growth do most clinically relevant bacteria fit in?

Answer 21

Facultative anaerobes - they prefer to reside in areas with oxygen but can survive in anaerobic conditions also.

Question 22

Define antibiotic.

Answer 22

An antimicrobial chemical substance that is produced by microorganisms

Question 23

Define growth-promotion use of antimicrobials in animals.

Answer 23

When healthy animals are treated with low (sub-therapeutic) concentrations in feed to improve growth rate and efficiency of feed utilization and improve reproductive performance.

Question 24

Drugs that end with -illin are ___.

Answer 24

Penicillins

Question 25

Drugs that end in -cline are ___.

Answer 25

Tetracyclines

Question 26

Drugs that end in -oxacin are __.

Answer 26

Quinolones (exception: oxolinic acid is also a quinolone).

Question 27

Drugs that end in -enicol are ___.

Answer 27

Phenicols

Question 28

Drugs that begin with cef- are ___.

Answer 28

Cephalosporins

Question 29

What groups of drugs would be a good choice for gram-positive bacterial infections?

Answer 29

Penicillins, Aminopenicillins, Amoxicillin/clavulanate, Cephalosporins.

Question 30

Which groups of drugs would be active against penicillase-producing staphylococci?

Answer 30

Amoxicillin/clavulanate, Cephalosporins, Fluoroquinolones

Question 31

Which groups of drugs are active against gram-negative rods?

Answer 31

Amoxicillin/clavulanate, Cephalosporins (3/4 generation), Fluoroquinolones, Aminoglycosides

Question 32

Which groups of drugs would be active against anaerobes?

Answer 32

Penicillins, Aminopenicillins, Lincosamides, Metronidazole, Amoxicillin/clavulanate

Question 33

What three groups of antimicrobials are beta-lactams?

Answer 33

Penicillins, Cephalosporins, Carbapenems

Question 34

Symbiotic mutualism

Answer 34

Both are necessary (host and bacteria) and the relation is positive for both.

Question 35

Symbiotic commensalism

Answer 35

Good for one, no problem for the other (i.e. intestinal flora)

Question 36

Symbiotic parasitism

Answer 36

One takes advantage of the other.

Question 37

Balanced pathogenicity

Answer 37

Damage with recovery.

Question 38

Which group of bacteria most often have flagella (gram positive or gram negative)?

Answer 38

Gram negative

Question 39

What are exotoxins?

Answer 39

Bacterial metabolites released by bacteria that interfere with normal cell function in surrounding cells.

Question 40

What are the characteristics of Type I endotoxins?

Answer 40

Binds with a cell receptor and leads to disturbances of cellular metabolism.

Question 41

What are the characteristics of Type II endotoxins?

Answer 41

Causes cell wall damage

Question 42

What are the characteristics of Type III endotoxins?

Answer 42

Intracellular toxins: one part binds to the membrane, the other part enters the cell.

Question 43

Balanced pathogenicity

Answer 43

Damage with recovery.

Question 44

Which group of bacteria most often have flagella (gram positive or gram negative)?

Answer 44

Gram negative

Question 45

What are exotoxins?

Answer 45

Bacterial metabolites released by bacteria that interfere with normal cell function in surrounding cells.

Question 46

What are endotoxins associated with gram negative bacteria?

Answer 46

Lipopolysaccharides (LPS) - lipid A is the pathogenic portion.

Question 47

What are endodoxins?

Answer 47

Cell wall components composed of lipopolysaccharides or lipoteichoic acids that cause fever/general sickness, tissue damage, CV shock and death.

Question 48

What are cell wall toxins of gram-positive bacteria?

Answer 48

Lipoteichoic acid (LTA).

Question 49

What's the role of membrane vesicles?

Answer 49

``` Pathogenesis Signaling Excretion of toxic products Killing of competitors Immunomodulation Excretion of bacterial toxic products Transformation ```

Question 50

Blood can be used for:

Answer 50

culture, serology and molecular genetics

Question 51

What types of bacteria are stained with acid fast stain?

Answer 51

Mycobacterium, nocardia, cryptosporidium

Question 52

What types of stains can be used to determine cellular association and morphology of bacteria?

Answer 52

H&E, Romanowsky, Wright's, Ciemsa, Diff-Quik, Gram stain

Question 53

What are the steps of Gram stain and what is the purpose of each step?

Answer 53

Fixation - use heat or alcohol Crystal Violet stain - adheres to the peptidoglycan layer of the gram + organisms. It cannot adhere to the peptidoglycan layer of gram - bacteria because it isn't accessible Iodine treatment - the "mordant". It interacts with the crystal violet, adhering it to the peptidoglycan layer of the gram+ organisms Decolorization - (alcohol wash) Removes crystal violet from the cell wall of the gram negative bacteria Counter stains (most often safranin)

Question 54

What is empirical treatment

Answer 54

treating what you believe is there without having a definitive diagnosis.

Question 55

What two elements are required in large amounts by bacteria to survive?

Answer 55

Carbon and nitrogen

Question 56

What do peptones provide for bacteria?

Answer 56

nitrogen, phosphate, sulfate, potassium, magnesium, calcium and iron

Question 57

What is a mesophile?

Answer 57

Bacteria that grows in moderate temperatures (~37 C)

Question 58

What is a psychotroph?

Answer 58

bacteria that can grow an reproduce in lower temperatures (10-15 C)

Question 59

What is selective media?

Answer 59

Media that allows growth for some types of bacterial species, but excludes others.

Question 60

Differential media

Answer 60

allows you to see some characteristic difference when grown on this media.

Question 61

List (3) basic nutrient media.

Answer 61

Trypticase Soy Agar (TSA) Luria Bertani (LB) Agar Mueller-Hinton (MH) Agar

Question 62

What is the difference between blood agar and chocolate agar?

Answer 62

Chocolate agar is lysed blood that's been heated (vs. just lysed agar)

Question 63

Which media is selective for gram positive bacteria?

Answer 63

Phenylethyl Alcohol Agar (PEA)

Question 64

Which media is selective for fungi (low pH)?

Answer 64

Sabouraud Dextrose (SabDex) Agar

Question 65

In what way is blood agar differential? Selective?

Answer 65

Easy to assess whether or not there is lysis and what kind of lysis occurs. It allows all the things to grow. Not selective.

Question 66

Describe the use of MacConkey Agar (MAC).

Answer 66

Selective for gram negative bacteria Differentiates between strains capable of fermenting lactose

Question 67

Describe the use of Mannitol Salt Agar (MSA).

Answer 67

Selective for gram positive bacteria Differentiates between strains capable of fermenting mannitol

Question 68

List three examples of ID test strips/plates used in identification of bacterial species.

Answer 68

Remel RapID, Sensititre, BD crystal

Question 69

What is the gold standard in molecular diagnostics of bacterial species?

Answer 69

16S ribosomal RNA PCR - 16S is the conserved component of 30S small subunit in prokaryotic ribosomes.

Question 70

What are nucleic acid multiplex or microarrays?

Answer 70

allow for detection of multiple bacterial species in a single sample. This is either PCR-based or uses tagged oligonucleotide probes in digested sample