U3 LEC: BACTERIAL CULTIVATION Flashcards
Microscopic examination of specimens provide preliminary information about a bacterial infection.
Bacterial Cultivation
Part of Kochβs postulate
What is seen in sample microscopy should be observed in sample culture
This provides definitive ID of a particular agent
Cultivation and isolation
Flow of Traditional ID
- Sample collection
2, Microscopy (stained/unstained) - Culture
- Microscopy of Culture
Flow of Alternative Bacterial ID
- Sample collection
- Culture
- Molecular testing
Normal flora of the throat
Moraxella catarhalis
One of the most sophisticated biochemical testing, just highly presumptive (not definitive and confirmatory)
VITEK
VITEK is best for?
Drug Susceptibility and Antimicrobial Susceptibility Testing
Purposes of bacterial cultivation
- grow and isolate all bacteria
- determine bacteria that are most likely causing infection
- obtain sufficient growth of clinically relevant bacteria
In vitro
artificial
In vivo
animals or human
In situ
environment
Key Terms
To introduce
Inoculation
Key Terms
Media that has the organism
Inoculum
Other Key Terms
- Incubation
- Cultures
- Colonies
- Isolation
Criteria for Growth Media
- sufficient moisture/water
- properly adjusted pH
- suitable level of oxygen
- sterile
- incubated at proper temp
- free from inhibitory substances
- must contain essential nutrients in proper concentration
Classification of Growth Media: According to Physical state
- Liquid
- Semi-solid
- Solid
- Biphasic media
This media can be observed in the blood culture bottle.
Biphasic Media
This is the first solidifying agent used.
Gelatin
At this percent, it can be used to detect presence of gelatinase.
12%
Red algae
Rhodophyta
Characteristics of Solid Media
- not degradable
- liquid at 55-60C
- solid at 50C or lower
- melts at high temperature (95-100C; Hysteresis)
According to dispensing/formation
- Plated medium
- Tubed
- Bottled
- Biphasic
Proper form of dispensed media
smooth, equal, molten liquid, no bubble formation, not too thin or thick
Kirby-Bauer Method
Mueller-Hilton Agar: neutral pH, 0.5 McFarland Standard, 4mm thick
This media can be used 5 days from preparation, prone to drying and contamination.
Plated Medium
T/F: If there is still liquid in plated media, you can still use it.
True
pwede pa basta moist environment
Screw Cap tubes lasts up to?
2 weeks to 1 month
Tubes with cotton lasts up to?
2 weeks
Matter of Dispensing
Plated
- Weigh
- Dissolve
- Autoclave
- Dispense
Matter of Dispensing
Tubed
- Weigh
- Dissolve
- Dispense
- Autoclave
Manner of Formation
Plated Medium
- Clock Method
- Radial
- Simple
Manner of Formation
Butt
Stab
Manner of Formation
Slant
Streak
T/F: Spreading is equal to seeding, but not equal to streaking.
True
Manner of Formation
Few growth in primary streak
very little growth
Manner of Formation
Growth only in primary streak
Little growth
Manner of Formation
Growth in primary and secondary streak
Moderate growth
Manner of Formation
Growth in primary, secondary, tertiary streak
Heavy growth
Manner of Formation
1 to 10 colonies only
Rare growth
According to Composition
- Chemically Defined / Synthetic
- Complex / Non-chemically defined
- Tissue Culture
According to Composition
Has defined compositions and concentrations
Chemically defined / Synthetic
According to Composition
Cannot be defined
Complex / Non-chemically defined
According to Composition
Examples of Complex / Non-chemically defined
Blood agar, Chocolate agar
According to Composition
This refers to organized tissues to look like organs, used for cancer treatment and bacterial culture
Organoids
According to function / use
- Basic / Basal / General Purpose
- Enriched Culture Media
According to function / use
Supportive media, for non-fastidious organisms
Basic/Basal/General Purpose
According to function / use
Fortified with nutrients, can grow some fastidious organisms
Enriched Culture Media
According to function
- Selective medium
- Differential medium
According to function
Refers to inhibitors
Selective Medium
According to function
Refers to inhibitors and indicators
Differential
According to function
This can differentiate one colony from the other
Indicators
Black colonies, hydrogen sulfide indicator
Salmonella agar
No hydrogen sulfide indicator
Shigella agar
Inhibitors for Gr (+) bacteria
- Dyes (gentian violet, crystal violet)
- Bile Salt (Sodium Desoxycholate)
Has crystal violet, selective for Gr (-) bacteria, differentiate for lactose and non-lactose fermenters
MacConkey Agar
Selective media for Staphylococcus sp.
Mannitol Salt Agar
According to function
This causes growth of enteric pathogens but will inhibit growth of Gr (+) bacteria
Bile Salt (Sodium Desoxycholate)
Inhibitors for Gr (-) bacteria
- Sodium azide
- Potassium tellurite
According to function
This is the best preservative for urine samples
Sodium azide
Selective Culture Media
For TB
Lowenstain Jensen Medium
Selective Culture Media
Lowenstain Jensen Medium is enriched in?
Albumin
Selective Culture Media
Inhibitor in Lowenstain Jensen Medium
Malachite green
Selective Culture Media
For Gram Positive (+)
Phenylethyl alcohol
Selective Culture Media
For Neisseria gonorrhoeae
- Thayer Martin
- Modified Thayer Martin
- Martin Lewis
- New York City Agar
Selective Culture Media
Inhibitor for Thayer Martin
- Vancomycin (Gr +)
- Colistin (Gr -)
- Nystatin (fungi)
Selective Culture Media
Inhibitor for Modified Thayer Martin
addition of Trimethoprim lactate
Selective Culture Media
Inhibitor for Martin Lewis
- Vancomycin
- Colistin
- Trimethoprim lactate
- Anisomicin (fungi)
Selective Culture Media
Inhibitor for New York City Agar
- Amphotericin B (fungi)
Mannitol Salt Agar
Inhibitor
7.5% NaCl
Mannitol Salt Agar
pH indicator
Phenol Red
Mannitol Salt Agar
Normal color, and color change
Normal: pink
Change: yellow
Thiosulfate Citrate Bile Salts Sucrose Agar
Inhibitor
- Thiosulfate
- Bile salts
- high pH
Thiosulfate Citrate Bile Salts Sucrose Agar
pH indicator
Bromthymol blue
Thiosulfate Citrate Bile Salts Sucrose Agar
Color of colonies
yellow and green
According to use
- Enrichment medium
- Transport medium
- Characteristic / biochemical characteristic medium
- Motility medium
- Antibiotic susceptibility
- Anaerobic / Reducing culture medium
- Pharmaceutical agar
- Media for capnophiles
According to use
Increases number of pathogens
Enrichment medium
According to use
Maintain viability
Transport Medium
According to use
Under enrichment medium
- Alkaline peptone water
- Tetrathionate
- Hafnia or gram negative broth
According to use
Under transport medium
- Amies, Cary-blair (Stool)
- Transgrow
According to use
Under biochemical
- Triple Sugar Iron Agar (Gram - bacteria; ability to ferment glucose, lactose or sucrose to produce H2S and gas)
According to use
under Motility medium
Sulfide Indole Motility (SIM)
According to use
under Antibiotic susceptibility
- Mueller Hinton Agar
- Middle Brook Agar (need high protein)
According to use
under Anaerobic
Bacteroides anaerobic medium (Additives that reduce O2)
According to use
under Pharmaceutical
research, no nutrients, pure agar
- Malunggay leaves
- Malco agar (coconut water)
Manifestations of Growth
Solid Media
Appearance of colonies
Manifestations of Growth
Liquid media
- Turbidity
- Presence of Pellicle
- Clot or coagulation
- Bubbles
Location in broth media
- Surface
- Column
- Bottom
When should you observe colony morphology?
18 to 24 hours postculture
This may affect size and characteristics of colonies
Age of culture
This determines the growth and colony morphology.
Plating media
Other term for plating media
Plate reading
T/F: Fastidious organisms require a longer time of incubation.
True