Ocular Microbiology and Antimicrobial Agents

Vocabulary flashcards for reviewing key terms and concepts in ocular microbiology.

Ocular Microbiology

An applied science focused on understanding and controlling eye infections through diagnostics and public health measures.

Prokaryotes

Microorganisms without chlorophyll, unicellular and does not show true branching. Examples include bacteria and blue-green algae.

Eukaryotes

Organisms with complex cellular organization. Examples include fungi, other algae, slime molds, and protozoa.

Micron (Micrometer)

Unit of measurement in bacteriology equal to one-thousandth of a millimeter.

Nanometer

One thousandth of a micron or one millionth of a millimeter

Angstrom unit

One tenth of a nanometer

Light Microscope

Microscope using light to visualize bacteria, either in living state or after fixation and staining.

Phase Contrast Microscope

Enhances contrast, revealing structures within cells that differ in thickness or refractive index.

Dark Field Microscope

Uses reflected light for improved contrast, allowing visualization of slender organisms like spirochetes.

Electron Microscope

Utilizes beams of electrons for high magnification and resolution, requiring a vacuum environment.

Simple Stains

Dyes such as methylene blue or basic fuchsin used to provide color contrast, imparting the same color to all bacteria.

Negative Staining

Uses dyes like Indian ink or nigrosine to create a colored background, highlighting unstained bacteria.

Impregnation Methods

Techniques using silver to make cells and structures visible under a microscope.

Differential Stains

Stains that impart different colors to different bacteria or bacterial structures, examples include Gram stain and Acid-fast stain.

Gram-positive bacteria

Bacteria with a thick peptidoglycan layer and teichoic acids in their cell wall.

Gram-negative bacteria

Bacteria with a complex cell wall containing lipids and a thin peptidoglycan layer. They also contain Lipopolysaccharides (LPS, endotoxin).

Cocci

Spherical or oval-shaped bacterial cells.

Bacilli

Rod-shaped bacterial cells.

Vibrios

Comma-shaped curved bacterial rods.

Spirilla

Rigid spiral-shaped bacteria.

Spirochetes

Flexuous spiral-shaped bacteria.

Actinomycetes

Branching filamentous bacteria.

Mycoplasmas

Cell wall-deficient bacteria with unstable morphology.

Binary Fission

The process by which bacteria divide, forming two daughter cells.

Lag Phase

Initial period in bacterial growth where there is no appreciable increase in number, but adaptation to the environment occurs.

Log Phase

Phase of exponential growth in bacterial populations.

Stationary Phase

Phase where cell division stops due to nutrient depletion and accumulation of toxic products.

Phase of Decline

Phase where population decreases due to cell death.

Phototrophs

Bacteria that derive energy from sunlight.

Chemotrophs

Bacteria that obtain energy from chemical reactions.

Autotrophs

Bacteria that can synthesize all their organic compounds.

Heterotrophs

Bacteria that cannot synthesize their own metabolites.

Aerobic bacteria

Bacteria that require oxygen for growth.

Anaerobic bacteria

Bacteria that grow in the absence of oxygen.

Microaerophilic bacteria

Bacteria that grow best in low oxygen tension.

Mesophilic

Bacteria that grow best at temperatures of 25-40°C.

Psychrophilic

Bacteria that grow best at temperatures below 20°C.

Thermophilic

Bacteria that grow best at high temperatures (55-80°C).

Thermal Death Point

The lowest temperature that kills a bacterium under standard conditions in a given time.

Plasmolysis

Osmotic withdrawal of water leading to shrinkage of protoplasm; caused by exposure to hypertonic solutions.

MRSA

Methicillin-resistant Staphylococcus aureus

Sterilization

Process that eliminates or kills all forms of microorganism from a substance.

Antimicrobial

Agent that acts against microbial organisms.

Antibiotic

A substance produced by a microorganism that acts against another microorganism.

Broad-spectrum antibacterials

Active against both Gram-positive and Gram-negative organisms.

Narrow spectrum antibacterials

Have limited activity and are primarily only useful against particular species of microorganisms.

Bactericidal drugs

Drugs that kill target organisms.

Bacteriostatic drugs

Drugs that inhibit or delay bacterial growth and replication.

Disinfectants

Antimicrobial agents applied to non-living objects to destroy microorganisms; does not kill all microorganisms.

Antiseptics

Destroy microorganisms on living tissue.

Normal Microbial Flora

Population of microorganisms that inhabit the skin and mucous membranes of healthy normal persons.

Conjunctivitis

Inflammation of the conjunctiva, commonly known as pink eye.

Blepharitis

Inflammation of the eyelids.

Keratitis

Inflammation of the cornea.

Endophthalmitis

Infection of intraocular fluids and tissue.

Orbital cellulitis

Infection of orbital tissue.

Canaliculitis

Infection and/or inflammation of the canaliculi.

The Five F's

Factors which influence the spread of trachoma infection which include Flies, Faeces, Faces, Fingers, and Fomites

SAFE Strategy

WHO recommended strategy for treating trachoma comprised of Surgery, Antibiotics, Facial Cleanliness and Environmental Improvements

Potentiative Interaction

When the antimicrobial effect of combining drugs is GREATER than the sum of the effects of the individual agents.

Giemsa stain

Microscopic stain of a conjunctival smear that highlights the typical Chlamydial inclusions

Chemoprophylaxis

The use of drugs to prevent disease

Selective Toxicity

The ability of a drug to injure a target cell or organism without injuring other cells or organisms that are in intimate contact

Antibiotic Stewardship

The determination to measure and increase how antibiotics are recommended by clinicians and used by patients.

Nosocomial infections

Hospital-acquired infections

Hyphae

branching filaments that make up the bodies of the organisms (Mycelia)

Mycelia

Collection of massed branched hyphae.