Intro to Bacteriology and Mycology Flashcards
History of the Germ Theory
-Accepted in 19th century
= microorganisms, known as pathogens, cause disease
-Ancient Greece: “seeds” in the air, or food, spread disease
1500s
Girolamo Fracastoro: “seed-like entities” could spread disease via direct or indirect contact as well as long distances
1600s
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
Spontaneous generation
The hypothetical process by which living organisms develop from non-living matter
1800s
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
Koch’s Postulates
- Microorganism must be found in abundance in all organisms suffering from the disease, but should not be found in healthy organisms
- The microorganism must be isolated from a diseased organism and grown in pure culture
- The cultured microorganism should cause disease when introduced into a healthy organism
- 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
Prokaryotes
No nucleus
- Bacteria and blue-green algae
- Archaebacteria and Eubacteria
Eukaryotes
Nucleus
-Protista, plantae, fungi, and animalia
Fungal cell structure
- 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
Gram staining
- 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
Mycoplasma cell structure
- Notable difference from other bacteria: NO cell well
- Requires special media to grow and special stains to visualize (i.e. Acid Fast)
Acid fast cell structure
- Stains mycolic acid in cell wall
- Staining procedure:
- -Carbol fuschin (red)
- -Heat
- -Decolorize with acid alcohol
- -Methylene blue
Size
- 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)
Flagellar arrangement
- Peritrichous
- Lophotrichous
- Amphitrichous
- Monotrichous
Special requirements - Atmosphere
- Aerobic
- Anaerobic
- Facultative anaerobic
- Capnophilic
- Microaerophilic
Aerobic
Grow only in the presence of free oxygen
-Ex: Pseudomonas sp.
Anaerobic
Grow only in the absence of free oxygen
-Ex: Clostridium sp.
Facultative anaerobic
Grow in the absence or presence of free oxygen
-Ex: E.coli and Staphylococcus sp.
Capnophilic
Requires 5-10% carbon dioxide
-Ex: Haemophilus sp.
Microaerophilic
Grow best in low oxygen levels
-Ex: Campylobacter sp.
Special requirements - Cells
- 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
Bacterial reproduction
- 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)
Clonal expansion
- 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.)
Fungal reproduction
- More complicated than bacterial reproduction
- Three types:
- -Vegetative: fragmentation, budding, fission
- -Asexual: spores (many types)
- -Sexual: formation and fusion of haploid gametes
Bacterial and fungal presence
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)
Biofilms
=Bacterial communities
- Anatomy:
- -Bacterial aggregate
- -Exopolysaccharides
- –Matrix formation
- -Complex
- Stages
- -Adhesion –> maturation
- Quorum sensing
- -Cell to cell “talk” via small molecules
- -Regulates gene expression
