Microbiology Week 7-9: Disease, Epidemiology, and Microbial Control

Disease

Any harmful deviation from the normal structure or function of an organism.

Syndrome

A group of signs and symptoms characteristic of a particular disease.

Signs

Objective and measurable indicators of disease (e.g., temperature, blood pressure).

Symptoms

Subjective experiences reported by the patient (e.g., pain, fatigue).

Communicable disease

A disease that can be spread from person to person.

Noncommunicable disease

A disease that cannot spread from person to person (e.g., tetanus).

Zoonotic disease

A disease transmitted from animals to humans (e.g., rabies).

Nosocomial infection

An infection acquired in a hospital setting.

Incubation period

The time from initial contact with a pathogen to the appearance of symptoms.

Prodromal stage

General symptoms begin to appear; pathogen is multiplying.

Period of illness

Pathogen multiplies at high levels; distinct signs and symptoms appear.

Period of decline

Symptoms lessen and pathogen numbers decrease.

Period of convalescence

Patient's strength returns; tissue repair occurs.

Koch's postulates

Used to identify the causative agent of a disease.

Reservoir

The natural habitat where a pathogen lives and multiplies.

Vector

An organism that transmits pathogens (e.g., mosquitoes).

Endemic disease

A disease that is constantly present in a population (e.g., malaria).

Epidemic disease

A disease that shows a sudden increase in cases in an area.

Pandemic disease

A disease that spreads worldwide (e.g., COVID-19).

John Snow

The father of epidemiology; traced cholera to contaminated water.

Florence Nightingale

A nurse who improved sanitation and reduced infectious deaths in war hospitals.

Morbidity rate

The number of diseased individuals in a population.

Mortality rate

The rate of death due to a disease.

CDC

To monitor notifiable diseases and publish the MMWR reports.

WHO

To coordinate global health and promote disease prevention.

Sterilization

The destruction of all microorganisms, including spores.

Disinfection

The elimination of vegetative pathogens but not spores.

Antisepsis

The reduction of microbes on living tissue (e.g., using iodine).

Sanitization

The mechanical removal of microbes to safe levels.

Degerming

The mechanical removal of microbes from skin (e.g., with alcohol swab).

Bactericidal

Kills bacteria.

Bacteriostatic

Inhibits bacterial growth.

Autoclave

A device using pressurized steam (121°C, 15 psi) to sterilize materials.

Pasteurization

Heat treatment that kills pathogens without altering food quality.

Incineration

Burning materials to achieve sterilization.

Moist heat vs. dry heat

Moist heat is more effective because it penetrates cells better.

Desiccation

The process of removing moisture.

Ionizing radiation

Uses gamma or X-rays to sterilize equipment and food.

Nonionizing radiation

UV light used for surface disinfection.

Filtration

Physically removes microbes from air or liquids (e.g., HEPA filter).

Halogens

Iodine and chlorine; destroy cellular components by oxidation.

Alcohols

Kill microbes by denaturing proteins and disrupting membranes.

Hydrogen peroxide

Used as a broad-spectrum antiseptic and sterilizer for surfaces.

Surfactants

Agents like soaps that remove microbes through mechanical action.

Magic bullet concept

An antimicrobial that targets pathogens specifically without harming the host.

Penicillin

Discovered by Alexander Fleming in 1928.

Sulfa drugs

Synthetic antibiotics that inhibit folate synthesis.

Antimicrobial resistance

When microbes adapt to survive exposure to drugs.

Beta-lactam antibiotics

Drugs like penicillin that inhibit cell wall synthesis.

Main challenge in antibiotic development

Drug resistance and high production costs.

Skin layers

Epidermis and dermis.

Lysozyme

An enzyme in tears that destroys bacterial cell walls.

Normal skin microbiota

Microbes that protect against pathogens by competition.

MRSA

Methicillin-resistant Staphylococcus aureus, a multidrug-resistant bacterium.

MRSA symptoms

Red, tender, pus-filled lesions; may include fever.

Impetigo

Caused by S. aureus and/or S. pyogenes infection forming blisters and crusts.

Cellulitis

A deep skin infection by Streptococcus or Staphylococcus.

Scalded skin syndrome

Caused by S. aureus releasing exfoliative toxins causing skin peeling.

Cutaneous anthrax

Caused by Bacillus anthracis, forming black eschars on skin.

Dermatophytes

Fungi causing ringworm; digest keratin in skin, hair, and nails.

Ringworm genera

Trichophyton, Microsporum, Epidermophyton.

Leishmaniasis

Caused by Leishmania spp., transmitted by sand flies.

Warts

Caused by Human papillomavirus (HPV).

Cold sores

Caused by Herpes simplex virus type 1 (HSV-1).

Chickenpox and shingles

Caused by Varicella-zoster virus (HHV-3).

Measles vs. rubella

Measles causes Koplik spots; rubella causes Forchheimer spots.

Bacterial conjunctivitis

Mainly caused by Staphylococcus aureus, Streptococcus pneumoniae, or Haemophilus influenzae.

Neonatal conjunctivitis

Caused by Neisseria gonorrhoeae or Chlamydia trachomatis during childbirth.

Keratitis in contact lens wearers

Caused by Pseudomonas aeruginosa.

Fungal keratitis

Caused by Fusarium or Aspergillus species.

Protozoan keratitis

Caused by Acanthamoeba.

Viral keratitis treatment

Antivirals, but steroids are contraindicated.

Conjunctivitis

Commonly called Pinkeye.

Main defense of the eye

Tears containing lysozyme and lactoferrin.

Immune privilege in the eye

Reduced immune response to prevent vision damage.