Lab Practical 3 Flashcards
Spore forming G+ bacilli
Bacillus
Clostridium, clostridioides (anaerobes)
Catalase positive G+ bacilli
Bacillus, corynebacterium, listeria
Acid fast stain mechanism
Ziehl neelsen - hot, heat makes dye penetrate cell wall
Kinyoun - cold, phenol dissolves lipid material and penetrates
Method: carbolfuchin stain, then counterstain
Appearance: bacteria red, other stuff blue
Modified acid fast stain for who? How does it work?
Aerobic actinomycetes
- Weak acid decolorizer instead of 3% HCL for mycobacteria
Which G+ rod grows on SBA and CHOC?
All Bacillus, Listeria, most corynebacterium but some don’t grow on CHOC like jeikeum
Nocardia
Corynebacterium diphtheriae special media is called and list properties
Cystine tellurite agar/modified tinsdale agar
- tellurite inhibits other growth and can reduce cystine
- positive for diphtheria: gray-black colonies
What special nutritional requirments do anaerobes have
Vitamin K and hemin
List the three main anaerobes
Clostridium, clostridioides, actinomyces
G+ rods and growth timing
- Bacillus: within 24 hours
- Listeria, Erysipelothrix, coryneform: within 48 hours
- Nocardia and aerobic actinomycetes: within 3-6 days and up to 4 weeks
G+ bacilli growth conditions
- Bacillus: 35-37 or in 5% CO2
- Listeria, erysipelothrix, coryneform: 35-37 air or 5% CO2
- Nocardia, aerobic actinomycetes: 37 C
Mycobacteria growth requirements
Strict aerobes, slow growing
30-45 C
Bacillus anthracis vs other bacillus on SBA
B. anthracis is non hemolytic and has filamentous “medusa head” colony growths, non motile
Elek test for what and how does it work
Immunodiffusion, tests for toxin of diphtheria
Listeria monocytogenes key characteristics
Hemolysis, motility, bile esculin, camp
Hemolysis: narrow beta
Motility: umbrella or tumbling at 25 C
Bile esculin: +
CAMP: +
Specimen collection for anaerobes
- Abscesses
- Aspirates
- Fluids
- Tissue
Swabs are discouraged
Gram stain of Clostridium and clostridioides
G+, spore forming rods
C. perfringens can be box car shaped
Gram stain of Actinomyces
G+, non spire forming, branching bacilli
Medium for bacteroides fragilis
BBE agar
Bacteroides bile esculin
Medium for bacteroides and prevotella
KVLB agar
Kanamycin-vancomycin laked blood agar
Medium for anaerobic bacteria
PEA agar
Phenylethyl alcohol agar
Clostridioides difficile medium
Cycloserine cefoxitin fructose CCFA agar
Gram stain for corynebacterium
V or L shape,clubs, palisades, G+ pleomorphic
List the 4 Misc. gram neg rods
Acinetobacter baumanni
Burkholderia cepacia
Stenotrophomonas maltophilia
Pseudomonas aeruginosa
Misc G- rods that are oxidase +
Burkholderia cepacia and pseudomonas aeruginosa
Only misc G- rod that is non motile
Acinetobacter baumanni
Campylobacter special medium
Campylobacter blood agar CAMPY-BA. selective enriched for C. jejuni from stool
Special medium for Vibrio
TCBS
Thiosulfate citrate bile salt sucrose agar
O/F medium mechanism
Two tubes, one aerobic and one anaerobic
- turns fully yellow if fermenter
- turns slightly yellow if oxidizer
- oil layer for true anaerobic conditions
Pigment production on MH medium
Pseudomonas aeuroginosa
Vibrio special growth requirements
Increased sale for all EXCEPT for V. cholerae
Who has darting motility
Campylobacter
O/129 disk susceptibility
Vibrio is sus
Campylobacter special gram stain appearance
S shape, sea gull wings
Burkholderia mallei vs pseudomallaei test differentiation
Mallei oxidase: -, variable, non motile
Pseudomallei oxidase: +, motile
Key points for lower respir tract diagnosis and collection
First morning sputum is the best
Key points for diagnosis upper respir. tract
- swabs are NOT for otitis media or sinitus
- Aspirates are better
- Throat specimens use thorough swabs
CNS diagnostic collection
- Before antimicrobial therapy
- Do not fridge CSF
- 2-4 blood cultures if bacterial meninigitis suspected
Clostridium difficile stool collection requirement
DIARRHEA WET SLOPPY LOOSE STOOL ONLY
UTI diagnostic collection key points
- If 3+ bacteria, suspect contamination
When do you need to work up a colony on a stool MAC
Clear colorless, rule out shigella and salmonella
When do you need to work up a colony on stool SMAC
Clear colorless, rule out O157
When do you need to work up a colony on stool HE
Blue/blue green (w or w/o black)
Rule out salmonella and shigella
Urine specimen colony count
1 microliter loop: multiply by x1000
10 microliter loop: multiply by x100
Direct smear report numbers
10x objective
WBCs
- 4+, >25
- 3+, 11-25
- 2+, 3-10
- 1+, <3
SEC
- >10 or <=10
Bacteria under oil
- 4+, >10
- Report gram and morph
Oxacillin/methicillin resistant staphylococci
what about it, what to do next
- Possess mecA gene
- Report as resistant to all beta-lactams
- Test with cefoxitin to predict mecA better
