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Microbiology II > Intro to Bacteriology: Collection & Diagnostics > Flashcards

Intro to Bacteriology: Collection & Diagnostics Flashcards

1
Q

Hierarch of Classification

A

Kingdom (Domain)
Division (Phylum)
Class
Order
Family
Genus
Species
Subspecies
“Strains”

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2
Q

Classification - Genus

A

Different species in same genus share common genetic/phenotypic features

Minor differences - different species within same genus

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3
Q

Classification - Species

A

Most basic taxonomic group

Common or similar physiologic and genetic features

Biotype and serotype - variants in the same species

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4
Q

Nomenclature Rules

A
  1. Names are in Latin/latinized
  2. First letter of genus capitalized, species is lowercase
  3. Italicized or underline
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5
Q

Phenotypic Identification

A

Macroscopic/microscopic traits
Nutritional/environmental requirements
Biochemical properties
Antigenic traits
Antibiotic resistance/susceptibility

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6
Q

Genotypic Identification

A

Nucleic acid traits

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7
Q

Gram Positive Cell Wall

Three main things + specific pathogenicity

A

Thick petidoglycan: cell shape, units of NAG linked to NAM

Teichoic/Lipoteichoic acid: negative charge, antigenic, role in pathogenicity (adherence), + cell division

Lipoprotein: cell transport

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8
Q

Gram Negative Cell Wall

Three main things + specific pathogenicity

A

Outer membrane: OM is for cell protection, permeability

Lipopolysaccharide (LPS): component of OM, antigenic, pathogenicity (endotoxin)

Thin peptidoglycan

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9
Q

Mycobacteria Cell Wall

Four main things + specific pathogenicity

A

Mycolic acid: cell protection, permeability

Araginogalactan: connects peptidoglycan to mycolic layer

Thin peptidoglycan

Lipoarabinomannan: cell wall integrity, antigenic, pathogenicity (immunomodulator)

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10
Q

Gram Stain Procedure

And bacterial appearance

A

Fixation
Crystal Violet
Iodine treatment
Decolorization
Counter stain safranin

Gram positive stain purple
Gram negative stain pink/red
Some are gram-variable or don’t stain

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11
Q

Acid Fast Stains

What for, three types of stains

A

High lipid and wax in bacteria cell walls don’t stain well with traditional stains

Ziehl-Neelsen: hot method
Kinyoun: cold method
Both use carbolfuschin

Fluorescent stain: auramine O for flurochrome dye

All of the above use phenol for penetration into cell wall

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12
Q

Endospore Stain

Basically what are spores and how are they different
What kind of bacteria form spores?

A

Gram positive bacteria can form spores (endospores for survival in harsh conditions)

Resistant to UV, temperature, chemicals

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13
Q

Capsule Stain

What do capsules have, what does it cause to normal stain?

A

Stains background with acid and cell using basic stain

Capsules have polysaccharides or polypeptides
Non ionic -> don’t stain with acid or basic stains

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14
Q

What method does bacteria use to multiply?

A

Binary fission
Generation time - time it takes for 1 cell -> 2 cells

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15
Q

Bacterial Growth Curve

4 phases

A

Lag phase: adapt to conditions, cells are maturing but not dividing

Log phase: cell doubling

Stationary phase: growth rate slows, nutrient depletion and more toxic products. Maximum cell number

Death phase: run out of nutrients and die

Bacteria produce more antibiotics and spores during stationary due to lack of nutrients

Antibiotics work on bacteria when they were at log phase

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16
Q

Heterotroph

A

Bacteria that inhabits human body

Require organic source of carbon

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17
Q

Nutritional Media Classifications

4 types

A

Non-inhibitory/nutrient: complex, extract of meat + soybeans

Enriched: added growth factors, blood, vitamins, enhaces growth of certain bacteria (ex. sheep’s blood)

Selective: agents that are inhibitory to some, allows growth of choice

Differential: visual metabolic characteristics, distinguish microbes growing (ex. MacConkey agar)

18
Q

Sheep Blood Agar

Three types of hemolysis

A

Contains RBCs

Alpha hemolysis: reduces RBC hemoglovin to methemoglobin, causes green/brown color

Beta hemolysis: complete lysis of RBC, clear zone on agar, bacteria can destroy RBCs

Gamma hemolysis: lacking lysis

19
Q

MacConkey Agar

Properties and visuals?

A

Differential properties: lactose positive produce pink colonies, lactose negative are colorless

Selective properties: G+ inhibited by bile salts and crystal violet, inhibits Proteus spp.

20
Q

Best pH for Bacterial Growth

A

Neutral (7-7.5)

21
Q

Temperature of Biological Growth

-philes and temperature ranges

A

Mesophilic: body temperatures (37 / 35-37 C)
Psychrophiles: cooler temperatures (4-20 C)
Thermophiles: warmer temperatures (42 C)

22
Q

Atmospheric Requirements for Growth

Oxygen?

A

Obligate aerobes: needs oxygen, 21%
Obligate anaerobes: no oxygen
Facultative anaerobes: aeorbic and anaerobic
Capnophiles: increased CO2
Microaerophiles: reduced oxygen, increased CO2

23
Q

Identification of Organism (Tests)

3 different types of tests

A

Biochemical enzymatic capabilites - can detect single enzymes, oxidation, fermentation, and amino acid degradation
Antigenic properties: using antibodies to detect pathogenic antigen (such as agglutination)
Resistance/susceptibility profiles: growth in certain inhibitory or toxic conditions (think zone of inhibition on a plate)

24
Q

Time of Collection for Testing

How time can affect the test

A

Acute phase: etiological agents more likely to be detected
Before antimicrobial therapy: some organisms are killed and cannot be recovered
Time of day: first morning is best for some

25
Q

Specimen Transport

A

Room temp: wound, body fluid, genital specimens, swabs in transport media
Fridge/frozen: specimens that are likely to contain microbial flora and viral specimens
- Neisseria meningitidis, N. gonorrhoeae, Heaemophilus influenzae are harmed by cold temps
Preservatives: urine/feces

26
Q

Specimen Processing Priority

A

Urgent: life-threatening
Routine: no risk, potentially important though
Elective: more confirmatory than diagnostic

27
Q

Specimen Processing Methods

3 ways to id bacteria

A

Macroscopic: consistency, volume, blood/mucus, color, clarity
Microscopic: quality of specimen, routine workup, additional testing
Culture media: use prior information to determine what kind of media is needed

28
Q

Blood Specimen Cultures

A

Collection: cleanse and draw correct blood amount according to adult or child
Prior to antibiotics/at fever spikes, 2-4 sets within 24 hours
Anaerobic and aerobic bottles
Next: gram stain, biochem tests, subculture to media

29
Q

Urine Specimen Cultures

A

Specimen collection: prevent contamination, refridgerated if not used after 30 minutes
Culture: calibrated loop, SBA and MAC media
Next: count colonies from SBA, idenitification

30
Q

Stool Specimen Cultures

A

Collection: taken during acute phase, process within 72 hours
Culture: routine pathogens, selective media, immunoassays available
Next: review plates and identify

31
Q

Respiratory Tract Specimen Cultures

A

Collection: avoid contamination, smear exam
Culture: onto media
Next: review plates and identify

32
Q

Catalase Assay

“Rapid” biochemical assay

A

Hydrogen peroxide in human cell, organisms must rely on defense to escape H2O2 damage
Catalase breaks down H2O2: positive test is when the sample bubbles with H2O2

33
Q

Coagulase

“Rapid” biochemical assay
Has two types of coagulation

A

Enzyme that clots fibrinogen containing plasma
Cell wall bound coagulase: acts directly on fibrinogen in plasma
Extracellular coagulase: liberated by the cells

34
Q

Pyrrolidony Peptidase (PYR)

“Rapid” biochemical assay

A

L-pyrrolidonyl-beta-naphthylamide hydrolyzed by the peptidase
Releases free beta-naphthylamide

Positive if ppink, orange, or red within 2 minutes

35
Q

Bile Solubility

“Rapid” biochemical assay

A

Sodium desoxylcholate lower surface tension in membrane and makes cells lyse easier

Positive if cells are lysed in 30 mins

36
Q

Oxidase

“Rapid” biochemical assay

A

Cytochrome C oxidase: oxidizes test reagent, porsitive if purple/blue in 30 seconds

37
Q

Butyrate

“Rapid” biochemical assay

A

Hydrolysis of bromo-chloro-indolyl butyrate and releases indoxyl
exposed to oxygen, forms indigo

Positive if blue-violet within 5 minutes

38
Q

Spot Indole

“Rapid” biochemical assay

A

Tryptophanase
Degrades into things + indole

Positive if red dye turns blue

39
Q

Urea Hydrolysis

“Rapid” biochemical assay

A

Urease
Forms ammonium carbonate, turns yellow alkaline media to pink

Positive if pink within 4-24 hours

40
Q

MALDI-TOF

What it does

A

Protein characterization
Matrix of sample mix ionized by laser beam, transfers charge to analytes and generates singly charged ions. These ions are separated based on mass to charge ratio and measured.

41
Q

Molecular Techniques

Pros, examples

A

Pros: high sensitivity, specificity, safety
Examples: hybridization, amplification, sequencing

42
Q

Serologic Tests

Pros, cons

A

Using antibodies and antigens
Pros: detect pathogens that are hard to culture, monitoring therapy
Cons: delay in antibody production, immunocompromised patients can have lower or no antibodies, cross reactivity

Microbiology II (16 decks)

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