Microbiology

Question 1

Microbiota

Answer 1

Microbiota = bacterial flora (but microbiota = preferred name now)

Question 2

Virulence

Answer 2

Relative ability to cause disease. Some bacteria are more likely to cause problems than others = more virulent

Question 3

(3) jobs of probiotics

Answer 3

1. inhibit the colonization & virulence expression of more pathogenic organisms
2. Synthesize useful nutrients OR utilize harmful chemicals
3. driving force in MUCOSAL immunity!

Question 4

Where in overall body do you find normal microbiota? Where should they not be?

Answer 4

On the skin (most superficial layers of epidermis + upper hair follicles).
Internal body/blood tissues/blood NEVER have normal microbiota. (Sometimes can get a few microbes in bloodstream, such as when brushing teeth, but tissue and blood is designed to be sterile).

Question 5

(5) areas of body where find normal microbiota

Answer 5

Nasal, oral, skin, GI, and urogenital tracts

Question 6

(3) things that microbiota on skin prefer for colonization

Answer 6

• Relatively dry (amount of moisture is most important thing on skin’s surface!)
• low pH
• sparse nutrients

Question 7

(3) most important conditions that regulate microbiota colonization in the mouth

Answer 7

• Moisture! Is not a limiting factor in mucosa like it is for skin
• flow of saliva will flush microbes out of system if they don’t stick to mucosal surfaces
• salivary secretions (amylase, lysozyme, immunoglobulins)

Question 8

Name (2) conditions that make people more susceptible to bloodstream disseminated infections. Give example of infection.

Answer 8

1. People with poor oral hygiene (b/c of increased bacterial load)
2. People w/ artificial joints, heart defects, etc (b/c of increased sites for bacteria to colonize)
   Ex. = Subactue Endocarditis

Question 9

What infection do HACEK bacteria cause increased the risk for?

Answer 9

Group of 5 bacteria that get into the bloodstream; Increased risk for sub-acute endocarditis.

Question 10

Normal v. Abnormal colonization of microbiota in respiratory tract

Answer 10

• Normal = epithelial surface of nasal cavity, nasopharynx, and Oropharynx
• NO colonization of the trachea, bronchi, and lungs!

Question 11

(3) environmental factors that affect microbiome colonization in respiratory tract.

Answer 11

• moist surfaces
• mucociliary clearance (remember, anything that interferes w/ this - e.g. Smoking - makes you MORE susceptible to infection)
• alveolar macrophages: some microbes are designed to live inside them (ex. Tuberculosis)

Question 12

Differences in colonization of small intestine, large intestine, stomach, and esophagus (I.e. Intestinal Tract)

Answer 12

• Small intestine = small #s of organisms
• Large intestine = large #s (highest in the body!)
• stomach = ONLY H. Pylori
• esophagus = NOT colonized

Question 13

Why is the colon so highly colonized by microbiota?

Answer 13

It’s anaerobic environment. So colon is a major source of anaerobes (and ONLY anaerobes)

Question 14

Where does C. Diff normally live? What about MRSA?

Answer 14

MRSA = nasal cavity

C. Diff = intestines

Question 15

colonized v. Non-colonized areas of genitourinary tract

Answer 15

• Colonized = epithelial surface of anterior urethra, vagina, and cervix
• NON-colonized = uterus, Fallopian tubes, or kidneys

Question 16

(2) environmental preferences of microbiota in GU tract

Answer 16

Moist surfaces & low pH in vagina

Question 17

Cause of Pelvic Inflammatory Disease (PID) and UTIs

Answer 17

• UTI: anal (intestinal) flora spread up urethra to the bladder and kidneys
• PID: normal vaginal flora spread to uterus and Fallopian tubes

Question 18

Most common organism in the vagina. What role does it play?

Answer 18

Lactobacillus species. It’s growth and fermentation of glycogen lower the pH, which helps regulate levels of other bacteria

Question 19

(3) most prominent intestinal bacteria

Answer 19

1. Streptococci (enterococci, Group B)
2. Escherichia coli (major cause of UTI)
3. Many different species of OBLIGATE anaerobes

Question 20

Overgrowth of what bacteria leads to bacterial vaginosis?

Answer 20

Gadnerella vaginalis - overgrowth leads to inflammation (vaginosis)

Question 21

Yeast infection caused by what species?

Answer 21

Overgrowth of Candida albicans

Question 22

(2) predominant skin bacteria

Answer 22

Staphylococci and diptheroids - both aerobic and anaerobic.

Ex. Anaerobic diptheroid = Propionibacterium acnes, which causes acne!

Question 23

Where is streptococcus normally found?

Answer 23

In mouth (cheek, tongue, teeth)

Question 24

E. in E. Coli stand for? What family is it in? Where does it normally live?

Answer 24

E. Coli = Escherichia coli. In the Enterobacteriaceae family. Predominant in intestines.