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microbiology 211 > Exam 3 > Flashcards

Exam 3 Flashcards

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1
Q

Methicillin Resistant Staphylococcus aureus (MRSA)
gram?
shape?
catalase?

A

gram positive
spherical, clusters
positive

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2
Q

MRSA normal microbiota

A

25% to 30% of population colonized in nose
Anterior nares
Skin

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3
Q

MRSA type of infection

A

Opportunistic infection
Carriers—Community-acquired infections
Autoinfection common

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4
Q

MRSA symptoms

A 
Boils
Warm to the touch
Pus
Superficial skin infections
if absess in subcutaneous skin=more serious=antibiotics
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5
Q

MRSA Treatment

A

drain boils, resolve on own
Vancomycin or teicoplanin-Now strains of MRSA showing resistance to these antibiotics
Vancomycin intermediate-resistant Staphylococcus aureus (VRSA) - 1997
New antibiotics approved by FDA
Linezolid (Zyvox)
Daptomycin (Cubicin)

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6
Q

MRSA Medical Emergency

A 
Spreading skin infection
Bone
Joints
Organs
Bacteremia
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7
Q

Methicillin Resistance

A

in 1959 was first semi-synthetic penicillin designed against penicillinases
S. aureus developed resistance UK 1961
Outbreaks in U.S. in late 1960’s
So prevalent that methicillin use is discontiuned in the U.S.
Resistant to other antibiotics – oxacillin, penicillin, amoxicillin, cephalosporins

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8
Q

Healthcare Aquired MRSA

A

Have weakened immune systems
Have wounds and open sores
Lots of exposure to antibiotics

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9
Q

Community Acquired MRSA

A

Young adults
Often sports teams or living in dormitories
More contagious but less virulent

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10
Q

MRSA Prevention

A 
Wash hands constantly
Barrier methods like gloves and gowns
Lots of disinfection
Correct handling of laundry
Don’t share personal items like soap or razors
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11
Q

difference between antibiotic and antimicrobial

A

antibiotic: used to kill microbes
antimicrobial: used to kill and prevent further growth of microbes

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12
Q

chemotherapy

A

the treatment of disease by the use of chemical substances, especially the treatment of cancer by cytotoxic and other drugs.

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13
Q

history of antibiotics

A

Alexander Fleming 1928
Penicillium notatum
Used beginning in 1940s

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14
Q

characteristics that make antibiotics effective

A

selectively toxic
Gram positive bacteria

Gram negative bacteria

Fungi and intracellular bacteria

Viruses

AND target something essential

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15
Q

selectively toxic

A

Chemotherapeutic agents should act against the pathogen and not the host

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16
Q

how do we characterize antibiotics

A

Bacteriocidal vs bacteriostatic

Broad spectrum vs narrow spectrum

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17
Q

Minimal Inhibitory Concentration (MIC)

A

lowest dose of drug needed to control microbial growth

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18
Q

Therapeutic dose

A

drug level for clinical treatment

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19
Q

Toxic dose

A

drug level at which it becomes toxic to host

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20
Q

action of antimicrobial drugs

see picture

A 
Inhibiting cell wall synthesis
Inhibiting protein synthesis
Inhibiting nucleic acid synthesis
Injury to cell membrane
Inhibiting synthesis of essential metabolites
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21
Q

Inhibition of cell wall synthesis

A 
Penicillin
Figured out the mode of action in 1956
Active against growing cells only
Poor activity against gram – bacteria
Destroyed by acid
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22
Q

Penicillin

A

contains beta-lactum ring(square)

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23
Q

solution to resistance

A 
Produced semi-synthetics
Penicillinase resistance
Active against Gram - 
Acid resistance
Less allergenic
Reach CNS
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24
Q

Antibiotics that affect cell wall

Monobactams

A

Low toxicity

Gm- like Pseudomonas

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25
Q

antibiotics that affect cell wall

Cephalosporins

A 
Structure similar to penicillin
Resistant to penicillinase
Effective against Gm-
Most injected
Expensive
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26
Q

Antibiotics that affect the cell wall
polypeptide antibiotics
Bacitracin

A

Effective against Gm+

Topical causes nephrotoxicity side effect

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27
Q

Antibiotics that affect the cell wall
polypeptide antibiotics
Vancomycin

A

Glycopeptide
Effective against penicillinase
Toxicity problems—limit use
Last line antibiotic for resistant Staphylococcus aureus strains

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28
Q

Antibiotics that affect the cell wall

Isoniazid (INH)

A

Inhibits mycolic acid synthesi
What bacteria would it be useful against? Tuberculosis
Good penetration ability

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29
Q

Antibiotics that affect the cell wall

Ethambutol

A

Inhibits incorporation of mycolic acid into cell wall

Used in combination to control resistance

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30
Q

Antibiotics that affect Protein Synthesis

Chloramphenicol

A 
Inhibit peptide bond formation
Broad spectrum
Inexpensive
Ready diffusion
Aplastic anemia
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31
Q

Antibiotics that affect Protein Synthesis

Aminoglycosides

A 
Cause misreading
Effective against Gm-
Toxic side effects
Kidney damage
Auditory nerve damage
Examples
Streptomycin
Gentamicin
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32
Q

Antibiotics that affect protein synthesis

Tetracycline

A 
Interfere with tRNA 
Benefits
Broad spectrum
Long retention time
Penetrate tissue
Problems
Not very bio-degradable
Side effects
Tooth discoloration in children
Liver damage in pregnant women
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33
Q

Antibiotics that affect protein synthesis

Macrolides

A

Gram+ only
Few side effects—children
Block tunnel

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34
Q

Injury to cell membrane

Polymyxin B

A 
Bacteriocidal
Gram-
Some toxicity so generally used topically
Triple antibiotic ointment
Polymyxin B
Bacitracin
Neomycin (aminoglycoside)
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35
Q

Inhibitors of Nucleic Acid Synthesis

Rifamycins

A 
Inhibits synthesis of mRNA
Penetrates tissue
Enters CNS
Side effect
Red urine, feces, saliva, tears, and sweat
36
Q

Inhibitors of Nucleic Acid Synthesis

Quinolones

A

Inhibits DNA gyrase
Bacteriocidal
Nalidixic acid—UTI’s

37
Q

Inhibitors of Nucleic Acid Synthesis

Fluoroquinolones

A

Synthetic quinolones
Broad spectrum
Nontoxic
Ciprofloxacin–anthrax

38
Q

Competitive Inhibition of Essential Metabolites

Sulfonamides (sulfa drugs)

A

Not antibiotics
Early therapy
Bacteriostatic
Blocks folic acid synthesis

39
Q

E Test

A

Gradient of antibiotics

Minimal Inhibitory Concentration

40
Q

Therapeutic Index

A

ratio between the toxic dose and the therapeutic dose

Measure of the relative safety of the treatment

41
Q

Antibiotic Resistance Mechanisms

A

Block entry
Inactivation of resistance enzymes
Alteration of target molecule
Efflux of antibiotic

42
Q

Factors Leading to Resistance

A 
Horizontal gene transfer: plasmids
-Hospitalization
-World travel
Overuse
-Patient demand
-Immunosuppression
Misuse
-Improper prescription
-Failure to follow treatment
-Long-term, low-dose use
-Use in animal feeds
43
Q

how are Microbial traits controlled or influenced by heredity.

A 
Shape
Metabolism
Structure
Ability to cause disease
Everything
44
Q

Why are chemotherapeutic agents that work on the peptidoglycan cell wall of bacteria a good choice of drug?

A

humans and animal hosts lack peptidoglycan cell walls

45
Q

To know flow of genetic information from genes to proteins

A

Understand how to control bacterial growth

How stop protein synthesis

46
Q

inhibiting cell wall synthesis

A
  • inhibiting synthesis of peptide cross links
  • inhibiting bonding of NAG and NAM
  • inhibiting lipopolysaccharide synthesis
  • inhibiting mycolic acid synthesis
47
Q

injuring the plasma membrane

A

inhibiting mycolic acid synthesis

48
Q

interfering with DNA replication

A

interfering with dna polymerase

interfering with dna gyrase

49
Q

interfering with RNA synthesis (transcription)

A

interfereing with RNA Polymerase

50
Q

interfering with protein synthesis

A
  • interfering with attachment of trna to mrna
  • interering with activity of 30S and 50S ribosomal unit
  • interfering with peptide bond formation, catalyzed by the ribosome
51
Q

which action of antimicrobial drugs would be bacterioSTATIC

A

inhibition of protein synthesis

52
Q

a cell dies from penicillin because…

A

it undergoes lysis

53
Q

The antibiotic tetracycline binds to the 30S subunit of the ribosome to…

A

interfere with the tRNA binding with the mRNA ribosome complex

54
Q

Genome

Eukaryote v. Bacteria

A

Eukaryotes—all the chromosomes

Bacteria—chromosome and plasmids

55
Q

DNA

A 
Nitrogenous bases
-adenine
-guanine
-cytosine
-Thymine
Deoxyribose
Phosphate
56
Q

Bacteria DNA

A 
Single chromosome
Haploid
Circular chromosome
No histones--packaged by DNA gyrase
Attached to the plasma membrane
57
Q

Eukaryote DNA

A 
Multiple chromosomes
Diploid or greater
Linear chromosomes
Histone packaging
Found in the nucleus
58
Q

DNA  RNA  Protein

A

DNA  DNA: Replication
DNA  RNA: Transcription
RNA  Protein: Translation

59
Q

1st step in DNA replication

A

The first step in DNA replication is the separation of the two DNA strands that make up the helix that is to be copied

60
Q

History of TB

A

Ancient disease—common in Greek and Egyptian writings
Epidemic in Europe and North America from 18th and into the 20th Centuries
Known at the White plague or consumption
#1 killer of people during this time
Better ventilation in homes and at work sites

61
Q

TB Causative agent

A

Mycobacterium tuberculosis
Acid Fast bacterium
Mycolic acid
#1 single infectious disease killer

62
Q

symptoms of TB

A 
Acute respiratory infection
Persistent cough with blood	
Constant fatigue
Loss of appetite and weight loss
Fever and night sweats
63
Q

transmission of TB

A

Transmitted by aerosols—prolonged contact

64
Q

Lungs of TBpatient

A

Grows in alveoli–causes tubercula in lungs
Small lumps
Body forms granulomas to defend

65
Q

Latent TB infection

A

carrier

66
Q

Active TB infection

A 
Only 10% of infected people develop the infection
Elderly and children
Immunocompromised
Smokers
People who live in crowded conditions
Without treatment very few survive
67
Q

Diagnosis of TB

A 
Mantoux PPD Skin Test
Inject tuberculin under skin of forearm
After 48-72 hours measure welt
15 mm or more is positive
Confirm with chest X-ray
68
Q

treatment of TB

A 
Multiple drug therapy
Isoniazid
Rifampin
Pyrazinamide
Ethambutol
Streptomycin
6 months to a year
69
Q

Prevalence of TB

A

less prevalent and less deaths

more people develop multi drug resistance bc not following directions probably

70
Q

Horizontal Gene Transfer (HGT)

A

Exchange of genes between two DNA molecules to form new combination of genes
Importance
Increased survivability
Contributes to genetic diversity

71
Q

Horizontal gene transferq

A

genes passed between bacteria
Transformation
Conjugation
Transduction

72
Q

vertical gene transfer

A

genes passed from parent to offspring

73
Q

HGT transformation

A 
Uptake of DNA from the environment
First discovered in 1928 by Griffith
Working with Streptococcus pneumoniae
Causes lethal respiratory infection
Requires a capsule for virulence
Capsule gene can be eliminated
74
Q

cells capable of transformation

A 
Recipient cells=Competent cells
Few species are naturally competent
Haemophilus
Bacillus	
Streptococcus
75
Q

conjugation

A

Transfer of DNA through pilus or direct contact
Fertility plasmid present in one cell–Donor
Self replicates
Contains genes
Make pilus
Enzymes to move the DNA across pilus
Cured if nonessential
Recipient cell does not contain the F plasmid

76
Q

Transduction

A

Transfer of DNA by a virus
Two mechanisms
Generalized transduction by lytic virus
Specialized transduction by lysogenic virus

77
Q

Generalized Transduction

A 
Host DNA gets degraded during viral replication
Virus packages host DNA in capsid
Defective virus
Able to infect new host cell
No viral DNA to replicate
New host genes
78
Q

Specialized Transduction

A

Lysogenic viruses
Becomes prophage—incorporates into genome
Get activated by some trigger
Come out of host genome and take host DNA with
Still able to replicate and infect new host

79
Q

vibrio cholorae

A 
Found in brackish water
Infectious dose: 
106 in water
104 in food
Not very resistant to acid
Serotype (150)
O1
Classical-–first 5 epidemics
El Torr—current epidemic
O139
80
Q

cholera symptoms

A 
Acute, diarrheal illness
Sudden onset of watery diarrhea
Rice water stool
5 gallons of water a day
Dehydration
No fever
1:10 people 
Death
Dehydration
Electrolyte imbalance
Mortality: 50% left untreated
81
Q

Enterotoxin Cholera

A

Makes epithelial cells highly permeable to water
Coded by the ctxAB gene
Carried by the CTX phage
Specialized transduction

82
Q

cholera transmission

A 
Fecal-oral
Water
Raw foods
Undercooked foods
Washing foods in contaminated water
Found in copepods and algae
83
Q

cholera treatment

A 
IV fluids
ORT
Oral Rehydration Therapy
Sugar-salt solution
Vaccination
Oral
Short duration
Mortality: 1%
84
Q

cholera today

A 
Seven pandemics since 1817
Four in the U.S.
1832
1849
1866
1887
Public health measures put into place
Cleaned up refuse
Contained animals
Instituted water treatment
85
Q

Failure in Public health-cholera

A 
Brought to Peru in 1991
Ship ballast water from Asia
Chlorinating water kills the bacterium
Lima, Peru—water system built by English
Handles a population of 230,000—population now 7 million

microbiology 211 (6 decks)

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