General Principles Of Microbiology And Laboratory Methods Of Identification Flashcards
What should be considered when choosing an ATB
- Severity or degree of risk
- Broad coverage with empiric antibiotics
- Timing
- Source control
- True infection bc colonization
- Antimicrobial resistance
How does severity or degree of risk guide us when choosing an ATB
- Aggressive Vs non aggressive
- Emergent vs non-emergent
How does broad coverage with empiric ATBs guide us when choosing an ATB
- Starting an ATB with board coverage in a timely manner can be lifesaving
*selecting the wrong dose, improper route, or delay treatment can increase morbidity and mortality
How does timing guide us when choosing an ATB
- Cultures and specimens should be obtained before ATB, when possible
*should not be delayed in life-threatening infection
How does source control guide us when choosing an ATB
- Drain collection of pus when possible
What are the signs of a true infection
- Almost accompanied by inflammation
- Neutrophils present
What are signs of contamination/colonization
- Large number of epithelial cells
- Growth of normal skin flora
*improper specimen collection
What is MIC
- Minimal inhibitory concentration
*lowest concentration of Antimicrobial agent (drug) that will inhibit the growth of the microorganisms
Do you want a low MIC or high MIC
Low
*also request a C&S
What does a low MIC mean on a culture
There will be a larger zone of inhibition
*small amount of drug goes a long way to kill the organism
What does a high MIC mean on a culture
There will be a smaller zone of inhibition
*a lot of a certain drug is needed to kill the organism
What is susceptible
Microorganisms is inhibited by a concentration of antibiotic and can be appropriately treated with that drug
What is intermediate Antimicrobial susceptibility
The ATB may be effective in high doses
What is a resistant Antimicrobial
Microorganisms is not inhibited by the antibiotic
*cant treat with that drug
What are some of the resistant microorganisms
- MRSA (methicillin resistant staph aureus)
- VRE (vancomycin resistant enterococcus)
What are some ways to diagnose infectious diseases
- Smear and stains
- Microscopic examination
- Cultures
- Tissue biopsy
How are smears and stains prepared
- By rolling a small amount of specimen across a glass slide
What are the different types of smears and stains
- Gram stain
- Giemsa stain
- Wright stain
- Acid-fast Bacilli
- Tzanck smear
What does the gram and giesma stains tests for
Gram: bacteria
Giemsa: microbes in tissue, H.pylori, chlamydia, malaria, histoplasma
What does the wright stain, and Acid-fast bacilli tests for
W: differential staining of blood smears, bone marrow, and blood parasites
A: TB and other types of mycobacteria
What does Tzanck smear test for
HSV, bulbous diseases
What is a gram stain used for?
- Bacterial differential stain
*will differentiate between different types of bacteria based on cell walls
How will gram neg and gram pos stain
+ purple
- red (do not retain crystal violet but take up safranin counterstain)
*if there is bacteria from a sterile site that is significant
How does yeast stain?
Purple
*will be a long pseudohyphae