PPT 11 (1)

Taxonomy

The science that studies organisms to arrange them into groups, or taxa.

Three-domain system

A classification system based on evolutionary relatedness, consisting of Bacteria, Archaea, and Eukarya.

Phylogeny

The evolutionary relatedness of organisms.

Taxonomic Hierarchies

The levels of classification in taxonomy, such as species, genus, family, etc.

Bergey’s Manual of Systematic Bacteriology

A manual that describes all known species of bacteria and classifies them according to genetic relatedness.

Phenotypic Characteristics

Observable traits of an organism used for identification, such as microscopic morphology, serology, and culture characteristics.

Nucleic acid amplification tests (NAATs)

Techniques like PCR used to increase the number of copies of specific DNA sequences for detection of organisms.

Sequencing Ribosomal RNA Genes

The process of determining the nucleotide sequence of ribosomal RNA genes, particularly the 16S rRNA which is commonly used due to its moderate size (~1,500 nucleotides).

Serology

The study of proteins and polysaccharides that serve as identifying markers, often used to detect surface structures of microorganisms like cell wall components.

Biochemical Typing

Grouping microorganisms based on characteristic biochemical patterns, such as biovars or biotypes, to differentiate strains.

Molecular Typing

Using molecular techniques like DNA analysis to characterize and differentiate strains, including methods like restriction fragment length polymorphisms (RFLPs) and multilocus sequence typing (MLST).

Phage Typing

A method to differentiate bacterial strains based on their susceptibility to bacteriophages, which has been largely replaced by molecular methods.

Antibiograms

Patterns of antibiotic susceptibility displayed by microorganisms, often determined by measuring clearing zones around antibiotic discs.

Classification of Prokaryotes

The process of categorizing prokaryotic organisms based on various traits, including phenotypic characteristics, DNA sequences, and evolutionary relatedness.

DNA Hybridization

Determining the relatedness of organisms by measuring the similarity of nucleotide sequences through DNA hybridization, with a higher percentage indicating closer relatedness.

DNA Base Ratio (G + C Content)

The ratio of guanine (G) and cytosine (C) bases in DNA, expressed as the GC content, which can be used to assess genetic relatedness between organisms.

Phenotypic Methods

Traditional methods of classifying microorganisms based on observable traits like size, shape, and metabolic capabilities, which are still important for prokaryotic identification despite advancements in genotypic classification.

B-lactam antibiotics

Antibacterial medications that interfere with peptidoglycan synthesis by inhibiting enzymes called penicillin-binding proteins (PBPs).

Penicillins

A family of antibacterial medications that vary in spectrum of activity and susceptibility to different types of enzymes, including natural penicillins, penicillinase-resistant penicillins, broad-spectrum penicillins, and extended-spectrum penicillins.

Carbapenems

Antibacterial medications with a broad spectrum of activity, not easily destroyed by most B-lactamases including extended-spectrum B-lactamases.

Monobactams

Antibacterial medications primarily active against Enterobacteriaceae, not inactivated by most B-lactamases but susceptible to extended-spectrum B-lactamases and some carbapenemases.