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BacT Final > General Bacteriology Summary > Flashcards

General Bacteriology Summary Flashcards

(69 cards)

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1
Q

What bacteria does not have Peptidoglycan?

A

Chlamydia

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2
Q

Which test detects endotoxin/Lipid A?

A

Limulus amebocyte

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3
Q

Bacteria structure summary

A

Prokaryotes (no nucleus), complex cell wall, no sterol, no membrane bound organelles, singular circular chromosome, no histones, ribosomes, no cytoskeleton, asexual reproduction (binary fission)

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4
Q

Flagella purpose

A

locomotion or motility

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5
Q

Fimbriae or pili purpose

A

adherence

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6
Q

Endoflagella/axial filaments present in…?

A

Spirochetes

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7
Q

Capsule purpose

A

Evade phagocytosis

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8
Q

Spore purpose

A

bacterial survival

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9
Q

T/F Size of bacteria is not critical to virulence of the species

A

True

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10
Q

Define: Pathogenicity

A

ability of a pathogen to produce a disease by overcoming the defense mechanisms of the host

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11
Q

Define: Virulence

A

degree of pathogenicity

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12
Q

Factors contributing to virulence

A
  1. Number of organisms
  2. Virulence factors
  3. Status of host immune response
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13
Q

Damage caused by bacteria

A

Using hosts nutrients,
direct damage to host cell (toxins),
hypersensitivity reactions,
type 4 hypersensitivity-Tuberculosis

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14
Q

What type of bacterial morphology is not common in clinical isolates

A

Gram Negative Cocci

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15
Q

Fungus Summary

A 
Eukaryotes, 
sterols (ergosterol) in cell membrane, 
no peptidoglycan (contains glucans, mannans, chitin)
yeast-unicellular, 
mold-multicellular (hyphae)
dimorphic fungus, 
sexual and asexual reproduction
polyphasic approach needed (morphology and DNA sequencing)
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16
Q

Detection of the infectious agent

A

Direct staining
Culture
ELISA (Ag detection)
PCR (Molecular detection)

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17
Q

Detection of the host immune response

A

Antibody detection (ELISA, Agglutination, precipitation, immunochromatography) and detection of cell mediated immune response (intradermal tests (tuberculin test), lymphocyte proliferation test)

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18
Q

Antibody Titer

A

It is the highest dilution of the serum sample which give a positive result in a particular test

remember: positive titer is not always diagnostic!

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19
Q

Does 1:256 or 1:16 Antibody titer have more antibodies?

A

1:256

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20
Q

Paired serology titers

A

compare acute and convalescent phase samples

Four fold increase in serum titers are indicative of infection

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21
Q

T/F Any bacteria can opportunistically infect any of the body systems

A

True

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22
Q

Define: systemic disease

A

Affect multiple systems of the body

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23
Q

When do you use antimicrobial therapy?

A

When the patient has a treatable microbial infection

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24
Q

What is MIC?

A

Minimum inhibitory concentration: minimum amount of drug required to inhibit bacterial growth, drugs with lower MIC values are better choices

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25
What is a susceptibility break point?
a drug concentration above which an organism is considered resistant and at or below this value organism is susceptible to that drug, three values (susceptible, intermediate, resistant)
26
Disk Diffusion "Kirby Bauer"
****Must use a bacterial isolate in pure culture, single concentration antimicrobial disks, growth inhibition zone diameter measured, published reference breakpoints to interpret results, qualitative- will not give you accurate MIC values
27
Which is more commonly seen- Full range or partial range MIC?
Partial range (breakpoint) MIC
28
Gradient diffusion test- E-test
***(diffusion and dilution) | can give you MIC values, but strips are very expensive
29
Time dependent killing
length of time bacteria are exposed to these antibiotics at a concentration above MIC, frequent dosing or constant infusions
30
Concentration dependent killing
rate of killing increases as the drug concentration in plasma increases above MIC, high dosing at long intervals (once daily) prolonged post antibiotic effect
31
concentration dependent killing antimicrobial drugs
fluoroquinolones, aminoglycosides, metronidazole
32
time dependent killing antimicrobial drugs
beta-lactams, macrolides, tetracyclines, lincosamides, chloriamphenicol potentiated sulfonmides cefovecin exception-binds above MIC for 7 days
33
Antimicrobials involved with cell wall/cell membrane
beta-lactams (penicillin, ampicillin, cephalosporins, imipenem), glycopeptides (vancomycin), bacitracin, polymyxin
34
Antimicrobials involved with protein synthesis
tetracyclines, macrolides, aminoglycosides, chloramphenicol, lincosamides, streptogramins
35
Antimicrobials involved with nucleic acid synthesis inhibition
sulfonamides/trimethoprim- folic acid synthesis (purine metabolism) nitroimidazoles/nitrofurans fluoroquinolons (enrofloxacin, ciprofloxacin) novobiocin, rifampin (RNA)
36
Antifungal drugs
polyens, azoles, bind to ergosterols
37
types of resistence
Innate resistance- preexisting genomic property | Acquired resistance- by mutation or horizontal gene transfer
38
which bacteria does not have a single circular chromosome?
Borrelia- linear chromosome | upregulation of OSP-variation, evades the immune system
39
Gram negative summary
only cell type that has outer membrane lipopolysaccharide (LPS)- lipid A/endotoxin is harmful Limulus amebocyte test to see lipid A
40
Gram positive summary
contain teichoic acid on cell walls | thick peptidoglycan layer
41
mycobacteria morphology summary
mycolic acid contribute to acid fast positive staining (but not the only acid fast bacteria!!!!)
42
Bacterial virulence factors
fimbriae, flagella, capsule, toxins (exotoxins and endotoxins), superantigens transfer of these through plasmids and bacteriophages by conjugation, transformation and transduction quorum sensing biofilms
43
Why is it important to know what type of pathogenicity a bacteria has? (opportunisitc, obligate nosocomial, obligate vs. facultative intracellular)
because you need to know these to be able to treat it
44
Staphylococcus summary
``` Gram + cocci (clusters) facultative anaerobe superantigen= enterotoxin suppurative conditions catalase positive ```
45
Streptococcus summary
``` Gram + cocci (pairs or chains) has M protein and teichoic acid superantigen catalase negative beta hemolytic (pyogenic) ```
46
What is the morphology of Rhodococcus
Gram + rod aerobe zoonotic mycolic acid/acid fast +
47
Bacillus anthracis summary
``` polymers of D glutamic acid spore forming (large spores) + mcfadyean reaction- pink capsule infectious, not contagious aerobe (bacillus sp is facultative anaerobe) ```
48
what bacteria are acid fast +
corynebacterium (partial) rhodococcus (partial) nocardia (partial) mycobacterium all are facultative intracellular
49
which bacteria are gram - anaerobes
fusobacterium bacteriodes dichelobacter
50
which bacteria are gram - spirochetes
brachyspira borrelia leptospira treponema
51
Cell wall deficient bacteria
mycoplasma | ureaplasma
52
gram - spiral bacteria
campylobacter helicobacter lawsonia
53
What bacteria has sterols in its cell membrane?
mycoplasma
54
what is seroconversion
antibody development after exposure to a pathogen or an antigen
55
things to remember about test results
1. generation or an immune repsonse requires time | 2. immune response may persist
56
what causes false positive
prior antigen exposure vaccination cross-reactions (sampling, transport, storage issues, antimicrobial therapy, presence of fastidious organisms, or when specific procedures are needed)
57
what causes false negative
early stages of infection late in infection due to anergy immunosuppression (sampling, transport, storage issues, antimicrobial therapy, presence of fastidious organisms, or when specific procedures are needed)
58
Antibacterial susceptibility testing
1. dilution (broth/agar) | 2. diffusion (disk)
59
Susceptibility results interpretation
S(susceptible)- high likelihood of therapeutic success I (intermediate)- uncertain therapeutic outcome R(resistent)- high likelihood of therapeutic failure
60
Broth diluartion
multiple dilutions of antimicrobial agents (usually 2 fold serial diluations) use published reference breakpoints to interpret measure and report growth inhibition endpoint (MIC- micrograms/mL)
61
bactericidal drugs
beta lactams, aminoglycosides
62
bacteriostatic drugs
chloramphenicol, tetracyclines
63
broad spectrum anitbiotic
tetracycline
64
narrow spectrum antibiotic
penicillin
65
antimicrobial combinations
1. to obtain antimicrobial synergism (ex. beta lactam aminoglycoside, sulfonamides/trimethoprim) 2. to treating polymicrobial infections (peritonitis/aspiration pneumonia) 3. to decrease the emergence of antimicrobial resistance (mycobacterial inf) 4. to reduce drug toxicity (flucytosine and amphorecin B in cryptococcal meningitis)
66
emergence of antimicrobial resistance
``` widespread antimicrobial use microbial adaptation and change changes in demopgraphics medical advances changes in ecosystems cutbacks in public health systems ```
67
mechanisms of resistance
enzymatic destruction of inactivation of drug prevention of penetration to target site within microbe alteration of drugs target site rapid efflux of antibiotics
68
potential impact of antimicrobial resistence
``` increased mortality due to infectious diseases vet revisits high treatment costs productivity loss and economic impact zoonotic spread of resistant microbes increased nosocomial infections ```
69
antibiotic misuse
providers- over prescription, over selection of broad spectrum, costly, last resort durgs clients/patients- noncompliance, stockpiling, self medication/OTC use in livestock rations for growth promotion and prophylaxis (80-90% of use in agriculture)

BacT Final (9 decks)

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