Lecture 24

Question 1

1. What are biofilms? What surfaces are ideal for biofilms?
2. Where are they found?
3. What are the two different states that bacteria can live in?

Answer 1

1. Microbial life on surfaces. Dry surfaces generally not suitable for microbial reproduction. Wet surfaces can be very suitable for microbial life.
2. Found in soil, lakes, streams, and all places where liquid exsists (e.g., inside the human body).
3. Planktonic (dispersed with the liquid) and Sessile (attached to surfaces covered by liquid).

Question 2

1. What type of compounds are adsorbed to and accumulate on surfaces?
2. What do these compounds promote?
3. What are bacteria protected by in biofilms?

Answer 2

1. Organic and inorganic compounds adsorb to and accumulate on surfaces, so surfaces often contain more nutrients for microbial growth than planktonic habitats.
2. Microbial cells can attach to these surfaces; by attaching, microbes can remain in a habitat favorable for reproduction.
3. In biofilms, bacteria are protected some from toxic chemicals (e.g., antibiotics).

Question 3

1. What is the general description of a biofilm?
2. What type of dental condition are biofilms related to?
3. What can a biofilm be made up from?
4. What are biofilms important to?

Answer 3

1. a “microbial slime” forming on surfaces in aqueous environments. An assemblage of surface-associated microbial cells enclosed in a matrix of extracellular polymeric substance (EPS, mostly polysaccharide)
2. The scummy film (plaque) on teeth, slippery boards at the lake, scum on dishes left sitting in the sink for a few days.
3. Can be made up of a single bacterial species (common in human disease) or a microbial community of microorganisms (common in the environment).
4. Important ecologically, industrially, and in human health.

Question 4

Biofilm Formation:

1. Attachment?
2. Colonization?
3. Development?
4. Active Dispersal?

Answer 4

1. Adhesion of a few motile cells to a suitable solid surface.
2. Intercellular communication, growth, and polysaccharide formation.
3. More growth and polysaccharide
4. Triggered by environmental factors such as nutrient availability.

Question 5

1. What precautions are being taken to fight against biofilms in defense terms?
2. What role do biofilms play in industry?
3. What role do biofilms play in medicine?
4. What are some bacterial infections caused by?
5. What are some biofilm diseases?
6. Why are bacteria in biofilms highly resistant to antibiotics.

Answer 5

1. Navy effort on developing anti-fouling paints, to allow ships to move through the water more easily (less fuel).
2. Lost industrial productivity, equipment damage, corrosion, costs of repair and maintenance.
3. Human health - Biofilms play a critic role in human health, lives lost and treatment costs.
4. Implants, secondary infections, reduced effectiveness of antibiotic therapy; reduced effectiveness of the immune response.
5. Gingivitis, peridontal disease, and dental carries. Otitis media, bacterial endocarditis, cystic fibrosis, Legionnair’s disease, nosocomical (hospital acquired) infections.
6. Antibiotics cannot penetrate the matrix of biofilm.

Question 6

1. What is gingivitis and periodontal disease arise from?
2. What does gum disease have major effect?
3. What does bacteria from plaque do?
4. How does do bacteria from plaque make it to lungs?
5. What is gum disease linked to?

Answer 6

1. Arise from poor dental hygiene, i.e., plaque build up.
2. Has a major effect on cardiovascular and pulmonary health.
3. Bacteria from the plaque enter the bloodstream through the swollen, infected gum tissue and can lodge in the tissues of the heart.
4. Bacteria from the plaque enter the lungs via the breath and can cause pneumonia.
5. Is linked to terminal illness:
   
   1. People with gingivitis - 23 percent higher risk.
   2. People with periodontal disease - 50 percent higher risk.

Question 7

1. What is the human microbiome?
2. What sites of the human body are inhabited by microbes?
3. Approx. how many microbes are in and on the human body?
4. Approx. how many human cells are there?
5. What is our microbiome is thought to play important roles?

Answer 7

1. The ecological community of commensal, symbiotic, and pathogenic microorganisms that share our body space.
2. Skin, mouth, nasal cavities, throat, stomach, intestines, urogenital tract.
3. Approx. 10¹⁴ (100 trillion)
4. Approx. 1 to 5 x 10¹³ (50 trillion)
5. Plays roles in our development, health, and predisposition to disease.

Question 8

1. What are some normal microbial residents of the human body - non-specific defense?
2. What do the microbes in the gut tract do?
3. What do the mircobes on the skin in the intestine and urogenital tract and elsewhere do?
4. What do normal microbial residents help with?

Answer 8

1. Many species of bacteria and many fungi are normally resident on and in the human body. Present in those regions of the body normally exposed to the environment. Skin, oral cavity, upper respiratory tract, intestinal tract, urogenital tract, these bacteria usually are beneficial; they are important for a normal state of health.
2. Vitamin synthesis (thiamine, riboflavin, B₁₂); synthesis of enzymes (breakdown of certain carbohyrates) and solubilization of fats.
3. On the skin and in the intestine and urogenital tract and elsewhere: preemption of living space and attachment sites that could be used by pathogens; alternation of physiological conditions (pH, oxygen, etc.) such that growth of pathogens is inhibited.
4. The presence of normal microbial resident of the body serves to block the entry or growth of pathogens. This is “non-specific defense”.

Question 9

1. How does age influnence non-specific defense?
2. How does stress influnence non-specific defense?
3. How does diet influnence non-specific defense?
4. What can damage to or weakening of non-specific defenses lead to?

Answer 9

1. Establishment of normal resident microbes in newborn children, general vitality and vitality of the immune system in elderly people.
2. Fatigue, inadequate nutrition, dehydration, tension, etc., predispose a person toward infection and disease.
3. adequate protein, minerals, and vitamins; consider for example sucrose - presence of surcrose in the diet correlates very strongly with the incidence of dental carries.
4. Can lead to invasion of the body by pathogenic bacteria, their survival and growth in the body, and the initiation of disease.

Question 10

1. What are resident microbes on the skin mostly associated with?
2. What are secreation of skin glands rich in?
3. Are most resident microbes of the skin gram-positive or gram-negative?
4. How does our skin protect us?
5. What type of defense is the skin?

Answer 10

1. Associated with the sweat glands and sebaceous glands of hair follicles.
2. Rich in urea, amino acids, salts, lactic acid, lipids; pH 4-6.
3. Most are grampositive (Staphylococcus, Corynebacterium, and Propionibacterium).
4. The surface of the skin is dry and shed continuously. The skin provides a major barrier to invasion of the body by microbes.
5. The skin is a non-specific defense - a physical barrier with the presence of normal resident microbes, presence fatty acids and lactic acid (low pH).

Question 11

1. What supports the growth of microbes in the respiratory tract?
2. How do bacteria enter the upper respiratory tract?
3. What are the resident microbes of the respiratory tract?
4. Describe the lower respiratory tract
5. What kind of defense does the respiratory tract have?

Answer 11

1. Mucous membranes
2. Bacteria enter through the air, are trapped in the nasal passages and removed in nasal secretions.
3. Staphylococcus, Streptococcus, normally present and some are potentially harmful, but usually do not cause illness; other resident microbes and the immune system keep them in check.
4. Essentially sterile; cilia line the respiratory tract, beating upward, removing particulates and bacteria; mucociliary clearance.
5. Non-specific defense - mucous (traps microbes), cilia (remove them)

Question 12

1. What makes up the oral cavity?
2. What is saliva?
3. What are lysozyme and lactoperoxidase?
4. What role does Streptococcus play in the oral cavity?
5. What else promotes plaque formation?

Answer 12

1. mouth, teeth, tongue
2. water, salts, low levels of carbohydrates, proteins, urea, ammonia, amino acids, vitamins - nutrients for bacteria.
3. lysozyme disrupts PTG of bacterial cell wall, lactoperoxidase generates singlet oxygen. Both of these enzymes are antibacterial.
4. Plays are role on dental carriers, single cell attach to tooth surface coated with salivary glycoproteins, grow to form microcolonies held together with mucopolysaccharide slime. Continued growth leads to plaque formation.
   
   1. Filamentous forms, Fusobacterium, actinomycetes, spirochaetes and many other types join in - a microbial zoo.
5. A diet high in sucrose promotes bacterial plaque formation and bacterial fermentation of the sugar to lactic acid dissolves tooth enamel.

Question 13

Urogenital Tract

1. Does the bladder contain bacteria?
2. What about the urethra?
3. What type of defense does the urethra have?

Answer 13

1. Usually sterile (no bacteria or yeast).
2. Has some Gram-negative facultatively aerobic bacteria (E. coli), can become opportunistic pathogens.
3. Non-specific: urination, flushes out microbes.

Question 14

GI tract

1. How many total microbes are present in the GI tract?
2. Are their bacteria in the stomach?
3. What kinds of bacteria are present in the the stomach?
4. How about the small intestine?
5. How about the large intestine?
6. What can intestinal bacteria influence?
7. How can we eliminate diseases?

Answer 14

1. 10¹² to 10¹⁴ microbial cells in the total GI tract.
2. Bacteria taken in with food, liquids; very few survive the low pH (pH of 2, non-specific defense) due to secretion of HCl acid.
3. Both Gram-negative and Gram-poistive bacteria, however, do colonize the stomach lining in low numbers, H. pylori.
4. Duodenum, fairly acidic, generally has a low number of bacteria like the stomach; jejunum to ileum, pH increases, oxygen decreases, bacterial numbers increase (10⁵ to 10⁷ per gram of contents).
5. Colon, facultative aerobes (E. Coli), consume all available oxygen, create conditions suitable for obligate anaerobes (Clostridum, Bacteroides, Enterococcus). Facultative aerobes, usually less than 10⁷ per gram. Obligate anaerobes, up to 10¹⁰ to 10¹¹ per gram.
6. May influnce several diseases. Such as, obesity, inflammatory bowel disease, type I diabetes, cancers, and live disease.
7. By changing the composition of the gastrointestinal microbiome, or introducing beneficial members of normal gastrointestinal microbiome.

Question 15

Microbial Composition of the Human Colon

1. Bacteroidetes?
2. Firmicutes?
3. Proteobacteria?
4. Actinobacteria?

Answer 15

1. 23% Gram-Neg.
2. 64% Gram-Pos.
3. 8% Gram-Neg.
4. 3% Gram-Pos.