INTRODUCTION TO MICROBIOLOGYBiology II

Mrs. Hieneman

DEFINITION OF MICROBIOLOGY• …the study of those organisms best

observed with the aid of a microscope.

• …employs techniques and procedures required to study microorganisms.

FIELDS OF MICROBIOLOGY• Bacteriology – prokaryotic cells• Virology – viruses• Mycology – fungi• Protozoology – protozoans (single celled

prokaryotes)• Parasitology – parasites• Immunology• Medical Microbiology• Microbial Genetics• Microbial Ecology• Biotechnology

ANTHON VAN LEEUWENHOEK• (1632 – 1723)

• Dry goods merchant

• Lens grinder

• Produced simple (single lens) microscopes

• In report dated Oct 9 1676 is the first description of bacteria.

LOUIS PASTEUR• (1822 – 1895)• Frenchman trained as

a chemist.• Discovered isomers of

tartaric acid.• Discovered the process

of fermentation and developed a method of “pasteurization” to reduce microbial contamination of wine and beer.

• Developed anthrax and rabies vaccines.

WHAT CAUSED DISEASE?• Humoral theory – an imbalance of the four

body humors (black bile, yellow bile, phlegm, blood) resulted in disease. Treatments: bloodletting, expectorants, purgatives.

• Demonic theory – cast out the demons; exorcists conducted this practice.

• Miasmatic theory – “something in the air” (miasma = poisonous vapor); malaria = bad air; influenza = influence of the stars.

• Germ theory – particulate matter transmissible from one person to another initiated disease.

GERM THEORY OF DISEASE• Agostino Bassi

– Silkworm disease caused by a fungus (1835)

• Ignaz Semmelweis

– Invisible agent caused sepsis (1841)

• M.J. Berkeley

– Potato blight of Ireland caused by a fungus (1857)

• Joseph Lister

– Introduced concept of sterile surgical field

– Use of antiseptics followed

– Developed limiting dilution technique

ROBERT KOCH (1843 – 1910)• German physician (and Pasteur’s rival)

• Studied the disease anthrax

• Developed a method to identify the etiologic agent.

• First utilized to identify Bacillus anthracis as etiologic agent of anthrax (1877)

• Developed a set of postulates

KOCH’S POSTULATES• The microorganism must be present in

the diseased host, and absent for the healthy.

• Microbe must be isolated and grown in a pure culture.

• Isolated microbe must cause disease when inoculated into healthy laboratory host.

• Must re-isolate the microbe from the diseased laboratory host.

BACILLUS ANTHRACIS• Large, aerobic, non-motile, gram positive,

spore-forming rod.

• Easily cultured on ordinary medium.

• Spores can be found in soil world wide.

• Affects humans and livestock

• Can be transferred from animals to humans.

ANTHRAX

ANTHRAX• Iran – 1945 outbreak killed 1 million sheep.

• Russia – 1979 accidental release of spores infected 79, killed 68 (inhalational anthrax)

• Easily weaponized to produce a biological warfare agent.

• Bioterror attack through U.S. Postal Service on East Coast Oct. 2001; 23 cases.

• 17 nations believed to have biological warfare programs

ANTHRAX• Incubation Period – (Time from initial

infection to appearance of symptoms) 1-7 days to a few weeks.

• Symptoms – onset of abrupt fever and chest pain, lethargy, progressing rapidly to a hemorrhagic pathology.

• NOT contagious from person to person

• THREE forms:– Inhalational, cutaneous, gastrointestinal

Cutaneous• Cutaneous anthrax usually occurs when spores

from the bacteria enter a cut or scrape on the skin. Cutaneous anthrax infection has the following characteristics:

• Skin infection begins as a small, raised bump that might itch-similar to an insect or spider bite.

• Within 1 to 2 days, the bump develops into a fluid-filled blister about 1cm to 3cm in diameter. Within 7 to 10 days, the blister usually has a black center of dying tissue (eschar) surrounded by redness and swelling. The blister is usually painless.

• Additional blisters may develop.

• Other symptoms may include:

• Swollen lymph nodes close to the area of the blister.

• Fever.

• Headache.

• A general feeling of discomfort.

Inhalational • The most lethal form of exposure occurs from

inhalational anthrax . The incubation period for this form of anthrax may be 60 days or more, although it is usually 2 to 3 days. Initial symptoms can include:

• Sore throat.

• Mild fever.

• Muscle aches.

• Symptoms can progress rapidly after just a few days to include:

• Severe difficulty with breathing.

• Shock, which can develop rapidly.

• Meningitis, which develops frequently.

• Death can occur within 24 to 36 hours after such complications occur. Respiratory symptoms may be similar to those of pneumonia.

Gastrointestinal• No confirmed cases of gastrointestinal anthrax have been reported in the United

States.2 This form of anthrax occurs after eating meat contaminated with the bacteria that cause anthrax. Gastrointestinal anthrax can be more serious than cutaneous anthrax but can be treated effectively with prompt use of antibiotics. But if untreated, gastrointestinal anthrax causes:

• Ulcers at the base of the tongue or tonsils.

• Sore throat.

• Loss of appetite.

• Vomiting.

• Fever.

• These symptoms are followed by:

• Abdominal pain.

• Vomiting of blood.

• Bloody diarrhea.

• Within 2 to 4 days after these symptoms develop, fluid (ascites) fills the abdomen; shock and death usually follow within 2 to 5 days.