Normal Flora

Most pathogenic organisms or opportunistic organisms have a _____ relationship with their host.

Parasitism

Staphylococcus epidermidis (a component of skin and eye flora) lives off human secretions and sloughed cells, but bring humans no benefit or harm. This is an example of: A) parasitism B) Antagonism C) commensalism D) mutualism

C) Commensalism

Intestinal flora produce bacteriocin, which does not affect the bacteriocin-secreting bacteria. However, bacteriocins inhibit growth of some pathogenic bacteria (like Shigella and Salmonella). The flora to shigella show what type of relationship? A) parasitism B) Antagonism C) commensalism D) mutualism

B) Antagonism

The vagina is about pH 4 due to bacterial flora products. This low pH prevents overgrowth by pathogenic Candida albicans. If the pH is disrupted (antibiotics, deodorants, hormone therapy), overgrowth of Candida occurs. This is an example of: A) parasitism B) Antagonism C) commensalism D) mutualism

B) Antagonism

When a baby is born what may be the first type of bacteria in their intestine?

Lactobacilli- normal birth Skin flora- born through cesarean section

Now that a baby has acquired normal flora... will its composition stay the same forever?

No!

What are examples of normal microbiota in the eyes (conjunctiva)?

Staphylococcus epidermidis, S. Aureus, propionibacterium, corynebacterium, streptococci

Why can normal microbial flora become opportunistic pathogens?

1. A member of the normal flora is introduced to an unusual site of the body 2. Immune suppression: disease, malnutrition, stress, very young, very old, chemo, immunosuppressive drugs, etc. 3. Changes in the normal flora

Streptococcus pyogenes is found in the digestive tract of humans, where it does not typically induce disease, however, if inoculated in the throat, it causes Strep Throat. The microbes in the digestive tract have what type of relationship with their host? The microbes in the throat have what type of relationship with their host?

1. Commensalism 2. Parasitism

What are the most abundant microbial habitats in the body?

1. Nose 2. Mouth 3. Skin 4. Respiratory tract 5. GI tract 6. Urogenital tract

Opportunistic pathogen: _____ is present at low levels in the normal vagina, if a woman has a long course of antibiotics, normal vaginal flora can die off, increase pH, allows this opportunistic pathogen to flourish.

Candida albicans

E. Coli is able to live in human hosts. Some strains may produce vitamin K and vitamin B, that enter the blood stream and are used by human cells. This is an example of: A) parasitism B) Antagonism C) commensalism D) mutualism

D) Mutualism

What are examples of normal microbiota in the skin?

Propionibacterium, Staphylococcus, Corynebacterium

What is microbial antagonism?

Simple competition between microbes for nutrients