CH 2 PART 1 Host-Parasite Interaction

When are we first introduced to microbes?

AT BIRTH we are STERILE until BIRTH

What are the 3 Microorganism relationships?

Commensalism

Parasitism

Mutualism

What happens in Commensalism?

Bacteria BENEFITS + human is UNHARMED

What happens in Parasitism?

Bacteria BENEFITS + human is HARMED

What happens in Mutualism?

Bacteria BENEFITS + Human BENEFITS

What are RESIDENT Flora?

Microorganisms colonizing FOR MONTHS OR YEARS

What are TRANSIENT flora?

TEMPORARY colonization

its just passing by

What is CARRIER STATE flora?

Microorganisms that are on host THAT CAN BE PASSED ON

What does the Composition of microbial flora depend on?

CONDITION of the body site

Nutrition, antibacterial substances, pH, moisture

What are the 5 sites where we have MICROBIAL FLORA?

1. Skin

2. Mouth

3. Respiratory Tract

4. GI tract

5. Genitourinary tract

How can normal flora on the skin become opportunistic?

When they are introduced to the STERILE SITES

What does the normal skin microbiota help to do?

PROTECTS the skin and prevent colonization of other microorganisms

What is the PREDOMENANT GENUS in the MOUTH?

Streptococcus

What can the normal flora in the mouth cause?

PLAQUE which is a BIOFILM

Which part of the Respiratory Tract should we expect to be colonized?

UPPER respiratory tract

Mouth, nasopharynx, larynx, oropharynx

Which part of the respiratory tract is STERILE?

LOWER respiratory tract

which is why we have to draw a DEEP COUGH to show status of lower resp tract

Which site of the GI tract is typically STERILE due to its acidic environment?

Stomach

Where are most microbes in the GI tract found?

INTESTINES FURTHER INTO THE GI TRACT

Which sites of the Genitourinary tract should be sterile/relatively sterile?

UPPER, the kidney, bladder, fallopian tubes etc

Which lower Genitourinary sites are expected to have NORMAL FLORA?

Vagina

Bacteria in the presence of what sites is an indicator of INFECTION?

STERILE sites

ALWAYS indicates an infection

What are examples of STERILE SITES?

1. Brain/CSF

2. BLOOD

3. Lower respiratory tract/ fluid associated with longs

4. Upper genitourinary tract

When do normal flora cause OPPORTUNISTIC INFECTION?

When introduced to a DIFFERENT SITE or IMMUNE COMPROMISATION

Skin flora → blood = infection

What are the 4 ways that normal flora protect the host?

1. Prevent COLONIZATION

2. Compete for NUTRIENTS

3. Produce inhibitory substances

4. Maintain local pH and other conditions