We are Not Alone

They are in the air we breathe . . .

In our food . . .

On our skin . . .

-on everything we touch.

They are . . .

microorganisms

What are microorganisms?

(also called microbes)

Microbes are small living plantsplants or animalsanimals most of which are not visible to the naked eye.

Some microbes cause diseasedisease or infectioninfection.

Many microbes are “good” “good” organismsorganisms that help keep balance in the environment and the body.

What microbes lack in size, they make up in

number.

On the average human, there are about 100 trillion microbes.

Good vs. Bad Microorganisms: 

Microorganisms that cause disease (germs) are referred to as pathogens.

 

Yeah, I’m bad.

Microorganisms that are harmless or beneficial are

called nonpathogens.

Most microbes are considered

beneficial or harmless.

87%

beneficial organisms

10%

opportunistsPathogens 3%

The role of good microorganisms

Marine & freshwater microbes form the basis of the food chain

in oceans, lakes, and rivers.

Soil microbes help break down

wastes.

Humans and other animals depend on

bacteria in their intestines for digestion and

synthesis of vitamins including:

vitamin B (for metabolism)

vitamin K (for blood clotting)

Microorganisms have many commercial applications

They are used in synthesis of chemical products such as:

acetoneenzymes

alcohol

organic acids

many drugs

They are used in the food industry for producing:

vinegarpickles

cheese

green olives

alcoholic beverages

yogurt

bread

Main Classes of Pathogenic Organisms:

1)Bacteria • simple one-celled organisms• At home within “climate” of human

body• compose largest group of pathogens

2)Fungi: yeasts & molds • Plant-like organisms that live on

dead organic matter• Grow best in dark, damp places

3) Viruses - smallest microbes

•acellular particles (not a complete cell)4) Protozoa

•one-celled animals often found in decayed materials & contaminated water5) Helminths

•parasitic worms

•caused by larval & egg infestations

Bacterial Infections

Impetigo

highly contagious bacterial infection

Extensive case of impetigo on underarm of baby.

Fetal Tetanus

(note severe muscle contractions)

Due to toxin production as a result of bacterial infection.

Diphtheria

Note swelling in neck

Diphtheria membrane

Cellulitis

An acute bacterial inflammation of

connective tissue.

Lymes Disease

hallmark “bulls-eye” lesion

Tiny deer tick vector that transmits lymes disease.

Fungal Infections

Candidiasis: Oral Thrush

Oral Thrush:

tongue

Candidiasis of Skin

Typical red, slightly most lesions.

Nail Fungus

Black Hairy Tongue

Cutaneous Fungal Infection: Tinea Versicolor

Note: hypopigmented fungal lesions

Cutaneous Fungal Infection: Ringworm

Cutaneous Blastomycosis: Hand & Wrist

Subcutaneous Blastomycosis

:

Manifested by subcutaneous abscesses in upper chest

Chromomycosis

Deep fungal infection with granulomatous

lesions.

Viral Infections

Viral Infection: Verruca Vulgaris (Wart)

Herpes Type I: Oral Herpes

More Oral Herpes

healing stage

Neonatal Herpes

Premature infant born with classic “cigarette burn” pattern of HSV

infection.

Poliomyelitis(also called infantile

paralysis)

Note: deformed right leg

Iron Lung: used by polio victims

Varicella (Chickenpox with oral involvement)

Measles

(rubeola)

Rash usually begins on face and spreads to

trunk and extremities.

Mumps: Note edema to cheeks and neck

Viral Hepatitis

Severely distended abdomen (ascites).

Secondary complication from hepatitis.

Parasitic & Protozoan Infections

Leishmaniasis

(protozoan systemic disease)

Severe nodular, disfiguring lesions

transmitted by sand fly

Dracunculiasis (Fiery Dragon Worm)

Found just under skin of human host.

Causes blisters at site of infestation.

Ulceration from worm.

A fiery dragon worm emerges from leg.

Elphantiasis

(filariasis)

Elphantiasisaffecting left leg and genitals

Intestinal helminthes cause infestations in intestinal tract and

abdominal organs such as the liver and spleen.

Always in pairs.

Helminthes which have infested the

liver.

hepatomegaly and ascites

Intestinal Roundworms

Mass of 800 worms removed from child’s ileum during autopsy

Loa Loa eye worm infestation in conjunctiva

Loa loa being extracted from under conjunctivia.

Hydatid cyst formed by tiny tapeworm that migrated to brain.

Summary

•Microbes are microscopic organisms

•About 100 trillion microbes live on the average human

•“Bad” microbes are pathogens

•About 3% of microorganisms are pathogenic

•Main classes of pathogenic microbes include: bacteria, fungi, viruses, protoza, & helminths

That’s all folks.