Bacterial classification and identification Flashcards
Phenotype
Characteristic displayed
Genotype
Genetic info in DNA
Why do we use rRNA sequences
- Present in all cells
- Large
- Universal sequence
- Signature region (specific or unique region)
Phylum of pathogenic bacteria
- Fermicutes- Gram +
- Proteobacteria- Gram - aerobic
- Bacteriodetes- Gram- anaerobic
- Spirochetes
- Chlamydia- Obligate intracellular organism
- Actinobacteria
Phenotypic characteristics used for identification
- Growth characteristics
- Cell morphology
- Biochemical reactions
What growth characteristics can be used to identify
- Grow in broth
- Grow on solid medium: look at colony morphology and growth on selective media
What parts of cell morphology can be used for identification
- Size and shape
- Stained or unstained
How can you diagnose UTI using growth characteristics
Sample plated on MacConkey agar that’s selective for Gram negative enteric bacteria. If pink indicates E. coli
Three staining techniques
- Simple
- Differential (gram and acid fast)
- Special (special structures)
What kind of special stains can you use
- Capsules
- Spores
- flagella
What types of dyes are generally used to dye bacteria
Basic dyes. Bacteria are acidic
What are ways to determine identification using biochemical characteristics
- Commercial rapid and miniaturized tests
- API kit
- MALDI-ToF mass spectrometry
What is MALDI-ToF
Laser hits the bacteria and vaporzies it and then it goes to the top and based on the charge and extent of charge it rises and is then detected. The profile is then matched to the correct bacteria
How do we use genotypic characteristics for identification
- PCR
- RT-PCR
- Whole genome sequences
What is typing of bacteria
Strains within a species that differ in characteristics including abilities to cause disease
