Identifying and Classifying Microorganisms

Flashcards covering the principles of taxonomy, phenotypic and genotypic identification methods, and strain characterization techniques from Chapter 10.

Taxonomy

The science of classifying organisms into groups, or taxa, based on phenotypic and genotypic relatedness.

Identification

The process of characterizing an organism in order to group it.

Classification

The process of arranging organisms into similar or related groups.

Nomenclature

A system of assigning names to provide universal identification for organisms.

Species (Prokaryotes)

A group of closely related isolates or strains, which are genetic variants or subtypes of a species.

Phylogeny

The study of evolutionary relatedness among organisms.

Carl Woese et al.

Researchers who developed the three-domain system based on rRNA sequences.

Gram stain

A microscopic morphology technique that distinguishes between Gram-positive and Gram-negative bacteria.

Serratia marcescens

A bacterium known for producing a red pigment when cultured at $22^{\circ} \text{C}$.

Pseudomonas aeruginosa

A bacterium that produces a green pigment and a distinct fruity odor in culture.

Streptococcus pyogenes

The causative agent of strep throat that forms $\beta$-hemolytic colonies on blood agar.

E. coli (on MacConkey agar)

An organism associated with urinary tract infections that ferments lactose and forms pink colonies.

Dichotomous key

A flowchart of tests with positive or negative results used to identify bacteria by asking successive questions regarding morphological or biochemical characteristics.

Serology

The use of antibodies to detect specific antigens such as proteins or polysaccharides of the cell wall, capsule, flagella, or pili.

NAATs (Nucleic acid amplification tests)

Techniques used to amplify specific sequences for the detection and identification of organisms that grow slowly or cannot be cultured.

Polymerase chain reaction (PCR)

A common technique used in NAATs to amplify specific DNA sequences for identification.

16S rDNA

The ribosomal DNA sequence used to identify prokaryotes and show their nearest relatives due to its little genetic variation.

Serovar (Serotype)

A group of microorganisms with characteristic antigens, such as $E. coli$ O157:H7.

DNA fingerprinting

A molecular typing method that uses restriction fragment length polymorphisms (RFLPs) to distinguish phenotypically identical strains.

Antibiograms

A method of identifying organisms based on antibiotic susceptibility patterns using discs impregnated with antimicrobials.