Intro to Bacteriology and Mycology

Question 1

History of the Germ Theory

Answer 1

-Accepted in 19th century
= microorganisms, known as pathogens, cause disease
-Ancient Greece: “seeds” in the air, or food, spread disease

Question 2

1500s

Answer 2

Girolamo Fracastoro: “seed-like entities” could spread disease via direct or indirect contact as well as long distances

Question 3

1600s

Answer 3

Francisco Redi

• -Meat and maggots experiment
• -Refutes spontaneous generation

Anton van Leeuwenhoek
–The first to observe microorganisms (“animalcules”) through his invention of the first microscope

Question 4

Spontaneous generation

Answer 4

The hypothetical process by which living organisms develop from non-living matter

Question 5

1800s

Answer 5

Louis Pasteur: experiment with flasks full of nutrient broth
–Bacteria come from other bacteria (cannot spontaneously generate)

Ignaz Semmelweis (1818-1865)

• -Hungarian obstetrician and pioneer of antiseptic procedures (handwashing)
• -Observed am births were preformed by midwives, pm births were performed by doctors and students coming from performing autopsies all day
• -Higher mortality rate in pm births
• -Implemented mandatory handwashing prior to assisting child births (reduced mortality from 18-2.2%)

Joseph Lister (1827-1912)
--British surgeon and pioneer of antiseptic surgery

Robert Koch

• -German bacteriologist
• -Anthrax, tuberculosis, and cholera
• -Koch’s Postulates

Question 6

Koch’s Postulates

Answer 6

1. Microorganism must be found in abundance in all organisms suffering from the disease, but should not be found in healthy organisms
2. The microorganism must be isolated from a diseased organism and grown in pure culture
3. The cultured microorganism should cause disease when introduced into a healthy organism
4. The microorganism must be re-isolated from the inoculated, diseased experimental host and identified as being identical to the original specific causative agent
   - -Postulates do not always work (asymptomatic carriers):
   - –Campylobacter sp. in dog diarrhea
   - –Pasteurella multocida in rabbit snuffles

Question 7

Prokaryotes

Answer 7

No nucleus

• Bacteria and blue-green algae
• Archaebacteria and Eubacteria

Question 8

Eukaryotes

Answer 8

Nucleus

-Protista, plantae, fungi, and animalia

Question 9

Fungal cell structure

Answer 9

• Similar to bacteria
• -Cell wall, cell membrane, and cytoplasm
• Different from bacteria
• -Fungi have a nucleus (eukaryotic)
• -Fungi have membrane bound organelles (i.e. mitochondria, ER, etc.)
• -Fungi can be multicellular
• Some have septae
• Some are branching

Question 10

Gram staining

Answer 10

• Used to determine bacterial morphology
• Devised by Hans Christian Gram, Danish physician, 1884
• Gram should be capitalized and never hyphenated when used as Gram stain; gram negative and gram positive should be lowercase and only hyphenated when used as a unit modifier
• -Gram staining
• -gram negative
• -gram-positive bacteria

Question 11

Mycoplasma cell structure

Answer 11

• Notable difference from other bacteria: NO cell well

- Requires special media to grow and special stains to visualize (i.e. Acid Fast)

Question 12

Acid fast cell structure

Answer 12

• Stains mycolic acid in cell wall
• Staining procedure:
• -Carbol fuschin (red)
• -Heat
• -Decolorize with acid alcohol
• -Methylene blue

Question 13

Size

Answer 13

• Rickettsia (0.3-0.5 uM)
• Staphylococcus (0.5-1.5 uM)
• E. coli (2-6 uM)
• Leptospira (5-20 uM)
• Ringworm conidia (7-20 uM)

Question 14

Flagellar arrangement

Answer 14

• Peritrichous
• Lophotrichous
• Amphitrichous
• Monotrichous

Question 15

Special requirements - Atmosphere

Answer 15

• Aerobic
• Anaerobic
• Facultative anaerobic
• Capnophilic
• Microaerophilic

Question 16

Aerobic

Answer 16

Grow only in the presence of free oxygen

-Ex: Pseudomonas sp.

Question 17

Anaerobic

Answer 17

Grow only in the absence of free oxygen

-Ex: Clostridium sp.

Question 18

Facultative anaerobic

Answer 18

Grow in the absence or presence of free oxygen

-Ex: E.coli and Staphylococcus sp.

Question 19

Capnophilic

Answer 19

Requires 5-10% carbon dioxide

-Ex: Haemophilus sp.

Question 20

Microaerophilic

Answer 20

Grow best in low oxygen levels

-Ex: Campylobacter sp.

Question 21

Special requirements - Cells

Answer 21

• Cell-free culture: most bacterial pathogens can grow on solid media
• Intracellular bacteria: require a cell culture
• -Ex: Chlamydia sp., Rickettsia sp.
• -Require eukaryotic cells to grow within
• -Diagnostics often include PCR or serology
• -Will not grow on blood agar

Question 22

Bacterial reproduction

Answer 22

• Binary fission = a method of asexual reproduction single-celled organisms use to create a copy of themselves
• Similar to mitosis, but not quite the same because mitosis requires making a copy of itself (binary fission does not)

Question 23

Clonal expansion

Answer 23

• A single cell becomes a colony
• 1 colony forming unit (CFU) = 1 bacterium
• Double time = generation time
• -The time it takes to complete one round of binary fission
• -Minutes to hours, depending on the bacterial species
• –Most have visible colonies in 18-48 hours
• –Some take longer (Brucella sp. and Mycobacterium sp.)

Question 24

Fungal reproduction

Answer 24

• More complicated than bacterial reproduction
• Three types:
• -Vegetative: fragmentation, budding, fission
• -Asexual: spores (many types)
• -Sexual: formation and fusion of haploid gametes

Question 25

Bacterial and fungal presence

Answer 25

Bacteria and fungi are ubiquitous (present, appearing, or found everywhere

• -Environment
• -Normal flora
• –Skin
• –MM
• –Teeth
• –Intestines
• -Pathogens
• –Opportunistic (part of normal flora)
• –Obligate (should not be there)

Question 26

Biofilms

Answer 26

=Bacterial communities

• Anatomy:
• -Bacterial aggregate
• -Exopolysaccharides
• –Matrix formation
• -Complex
• Stages
• -Adhesion –> maturation
• Quorum sensing
• -Cell to cell “talk” via small molecules
• -Regulates gene expression