medlab

Bacteria Naming Convention

Bacteria are named by genus (capitalized) and species (lowercase). Example: Streptococcus pyogenes.

Cell Wall

Determines shape; site for many antibiotics; classifies bacteria into Gram-positive and Gram-negative.

Cell Membrane

Thin, lipid-protein layer inside the cell wall; regulates material exchange.

Chromosome

Circular double-stranded DNA that contains genetic information.

Nucleoid

Area in the cytoplasm that houses the chromosome.

Cytoplasm

Liquid matrix (mostly water) with nutrients and wastes.

Plasmid

Extra, smaller DNA that can transfer between cells.

Pili

Hair-like structures used for attachment and plasmid exchange.

Ribosomes

Site of protein synthesis; bacterial ribosomes are 70S.

Flagella

Structures responsible for motility.

Endospores

Resistant forms of bacteria under unfavorable conditions.

Liquid (Broth)

Growth medium in suspension.

Solid

Growth medium solidified with agar (1.5%).

Semi-Solid

Contains less agar (0.7%).

Enrichment Media

Media that enhances the growth of specific organisms.

Blood Agar Plate (BAP)

Medium that shows hemolysis patterns (alpha, beta, gamma).

Selective Media

Inhibits certain organisms while promoting others.

CNA

Medium that enhances Gram-positive species.

Differential Media

Media that distinguishes organisms based on characteristics.

Mannitol Salt Agar (MSA)

Differentiates Staphylococcus species.

MacConkey Agar (MAC)

Identifies lactose fermenters and non-fermenters.

Aerobic

Requires oxygen to survive.

Anaerobic

Cannot tolerate oxygen.

Microaerophilic

Requires low levels of oxygen.

Facultative

Can grow with or without oxygen.

Acidophiles

Bacteria that prefer pH less than 5.0.

Neutrophiles

Bacteria that prefer pH between 6.0 and 8.0.

Alkaliphiles

Bacteria that prefer pH greater than 9.0.

Psychrophiles

Bacteria that thrive at temperatures from 0°C to 20°C.

Mesophiles

Bacteria that thrive at temperatures from 20°C to 45°C (most pathogens).

Thermophiles

Bacteria that thrive at temperatures greater than 45°C.

Osmotic Pressure

Essential in food preservation; most bacteria are inhibited in over 1% salt.

Sterilization

Process that eliminates all microbes.

Disinfection

Process that reduces microbial load, but does not completely kill.

Antiseptics

Substances that reduce microbial growth on living tissues.

Bactericidal

Substances that kill bacteria.

Bacteriostatic

Substances that inhibit bacterial growth.

Streak Plating

Technique for isolating colonies from mixed cultures.

Gram Staining Reagents

Crystal Violet, Iodine, Alcohol, Safranin.

Gram Staining Results

Determine bacteria as Positive (purple) or Negative (pink) based on cell wall structure.

Streptococcus pyogenes

Causes strep throat and scarlet fever.

Streptococcus pneumoniae

Causes pneumonia.

Staphylococcus aureus

Causes boils, carbuncles, pneumonia, and septicemia.

Escherichia coli

Causes urinary tract infections.

Pseudomonas aeruginosa

Causes respiratory and urogenital infections.

Neisseria gonorrhea

Causes gonorrhea.

Normal Flora

Beneficial bacteria that prevent pathogenic colonization.

Pathogen Acquisition

Methods including aerosols, contact, ingestion, and vectors.

Catalase Test

Distinguishes staphylococci from streptococci.

Coagulase Test

Positive in Staphylococcus aureus.

Oxidase Test

Differentiates Pseudomonas from Enterobacteriaceae.

Monotrichous Flagella

Bacteria with a single flagellum.

Lophotrichous Flagella

Bacteria with a tuft of flagella at one end.

Peritrichous Flagella

Bacteria with flagella distributed all over the surface.

Amphitrichous Flagella

Bacteria with flagella at both ends.

Atrichous Flagella

Bacteria with no flagella.