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BacT Final > General Bacteriology Summary > Flashcards

General Bacteriology Summary Flashcards

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
Q

What is a susceptibility break point?

A

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)

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26
Q

Disk Diffusion “Kirby Bauer”

A

**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

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27
Q

Which is more commonly seen- Full range or partial range MIC?

A

Partial range (breakpoint) MIC

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28
Q

Gradient diffusion test- E-test

A

***(diffusion and dilution)

can give you MIC values, but strips are very expensive

29
Q

Time dependent killing

A

length of time bacteria are exposed to these antibiotics at a concentration above MIC,
frequent dosing or constant infusions

30
Q

Concentration dependent killing

A

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
Q

concentration dependent killing antimicrobial drugs

A

fluoroquinolones, aminoglycosides, metronidazole

32
Q

time dependent killing antimicrobial drugs

A

beta-lactams, macrolides, tetracyclines, lincosamides, chloriamphenicol potentiated sulfonmides
cefovecin exception-binds above MIC for 7 days

33
Q

Antimicrobials involved with cell wall/cell membrane

A

beta-lactams (penicillin, ampicillin, cephalosporins, imipenem), glycopeptides (vancomycin), bacitracin, polymyxin

34
Q

Antimicrobials involved with protein synthesis

A

tetracyclines, macrolides, aminoglycosides, chloramphenicol, lincosamides, streptogramins

35
Q

Antimicrobials involved with nucleic acid synthesis inhibition

A

sulfonamides/trimethoprim- folic acid synthesis (purine metabolism)
nitroimidazoles/nitrofurans
fluoroquinolons (enrofloxacin, ciprofloxacin)
novobiocin,
rifampin (RNA)

36
Q

Antifungal drugs

A

polyens, azoles, bind to ergosterols

37
Q

types of resistence

A

Innate resistance- preexisting genomic property

Acquired resistance- by mutation or horizontal gene transfer

38
Q

which bacteria does not have a single circular chromosome?

A

Borrelia- linear chromosome

upregulation of OSP-variation, evades the immune system

39
Q

Gram negative summary

A

only cell type that has outer membrane
lipopolysaccharide (LPS)- lipid A/endotoxin is harmful
Limulus amebocyte test to see lipid A

40
Q

Gram positive summary

A

contain teichoic acid on cell walls

thick peptidoglycan layer

41
Q

mycobacteria morphology summary

A

mycolic acid
contribute to acid fast positive staining
(but not the only acid fast bacteria!!!!)

42
Q

Bacterial virulence factors

A

fimbriae, flagella, capsule, toxins (exotoxins and endotoxins), superantigens
transfer of these through plasmids and bacteriophages by conjugation, transformation and transduction
quorum sensing
biofilms

43
Q

Why is it important to know what type of pathogenicity a bacteria has? (opportunisitc, obligate nosocomial, obligate vs. facultative intracellular)

A

because you need to know these to be able to treat it

44
Q

Staphylococcus summary

A 
Gram + cocci (clusters)
facultative anaerobe
superantigen= enterotoxin
suppurative conditions
catalase positive
45
Q

Streptococcus summary

A 
Gram + cocci (pairs or chains)
has M protein and teichoic acid
superantigen
catalase negative
beta hemolytic (pyogenic)
46
Q

What is the morphology of Rhodococcus

A

Gram + rod
aerobe
zoonotic
mycolic acid/acid fast +

47
Q

Bacillus anthracis summary

A 
polymers of D glutamic acid
spore forming (large spores)
\+ mcfadyean reaction- pink capsule
infectious, not contagious
aerobe (bacillus sp is facultative anaerobe)
48
Q

what bacteria are acid fast +

A

corynebacterium (partial)
rhodococcus (partial)
nocardia (partial)
mycobacterium

all are facultative intracellular

49
Q

which bacteria are gram - anaerobes

A

fusobacterium
bacteriodes
dichelobacter

50
Q

which bacteria are gram - spirochetes

A

brachyspira
borrelia
leptospira
treponema

51
Q

Cell wall deficient bacteria

A

mycoplasma

ureaplasma

52
Q

gram - spiral bacteria

A

campylobacter
helicobacter
lawsonia

53
Q

What bacteria has sterols in its cell membrane?

A

mycoplasma

54
Q

what is seroconversion

A

antibody development after exposure to a pathogen or an antigen

55
Q

things to remember about test results

A
  1. generation or an immune repsonse requires time

2. immune response may persist

56
Q

what causes false positive

A

prior antigen exposure
vaccination
cross-reactions

(sampling, transport, storage issues, antimicrobial therapy, presence of fastidious organisms, or when specific procedures are needed)

57
Q

what causes false negative

A

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
Q

Antibacterial susceptibility testing

A
  1. dilution (broth/agar)

2. diffusion (disk)

59
Q

Susceptibility results interpretation

A

S(susceptible)- high likelihood of therapeutic success
I (intermediate)- uncertain therapeutic outcome
R(resistent)- high likelihood of therapeutic failure

60
Q

Broth diluartion

A

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
Q

bactericidal drugs

A

beta lactams, aminoglycosides

62
Q

bacteriostatic drugs

A

chloramphenicol, tetracyclines

63
Q

broad spectrum anitbiotic

A

tetracycline

64
Q

narrow spectrum antibiotic

A

penicillin

65
Q

antimicrobial combinations

A
  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
Q

emergence of antimicrobial resistance

A 
widespread antimicrobial use
microbial adaptation and change
changes in demopgraphics
medical advances
changes in ecosystems
cutbacks in public health systems
67
Q

mechanisms of resistance

A

enzymatic destruction of inactivation of drug
prevention of penetration to target site within microbe
alteration of drugs target site
rapid efflux of antibiotics

68
Q

potential impact of antimicrobial resistence

A 
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
Q

antibiotic misuse

A

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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