Microbiology short answer portion

ideal chemotherapeutic agent

1. toxic to pathogens

2. not toxic for host

3. does not cause antibiotic resistance

4. no hypersensitivity in host

5. does not interfere with normal defense mechanisms

6. soluble

7. stable

8. long shelf life

9. affordable

factors influencing the effectiveness of microbial drugs

1. ability to reach infection

2. susceptibility of pathogen

3. must exceed pathogen’s MIC (amount administered, route of administration, speed of uptake, rate of clearance)

4. drug resistance

mechanisms of drug resistance

• efflux pump

• inactivation of enzymes

• blocked penetration

• target modification

five periods of disease

1. incubation - after initial entry

2. prodromal - continues to multiply

3. period of illness - signs and symptoms most severe

4. period of decline- number of pathogen begins to decline

5. period of convalescence - return to normal

stages of pathogenicity

exposure or contact, adhesion, invasion, infection

portals of entry

eyes, nose, mouth, placenta, vagina, urethra, anus, broken skin, needle, insect bite

portals of exit

eyes, mammary glands, placenta, vagina, urethra, skin, nose, mouth, ear, broken skin, insect bite, needle, anus

non-specific defense (skin)

• intact/no abrasions

• langerhan cells

• sheds

• sebum

• oily

• salty

• S.A.L.T. - skin associated lymphatic tissue

• keratinize

• s. aureus, s. epidermidis, lactobacillus

• hair

non-specific defense (nose)

• same organisms as skin

• cilia

• mucous

• M.A.L.T. - mucous associated lymphatic tissue

non-specific defense (mouth)

• cough

• sneeze

• laugh

non-specific defense (ears)

• wax

• cilia

non-specific defense (eyes)

• eyelashes

• tears

• lysozyme

non-specific defense (upper respiratory)

• cilia

• mucous

• MALT - mucous associated lymphatic tissue

• BALT - bronchial associated lymphatic tissue

non-specific defense (stomach)

• low pH

• mucous

• MALT - mucous associated lymphatic tissue

• GALT - gut associated lymphatic tissue

non-specific defense (vagina)

• self cleaning

• mucous

• MALT - mucous associated lymphatic tissue

non-specific defense (urinary tract)

• flushes

non-specific defense (large and small intestine)

• over 300 normal microbiota

mechanisms of action

• inhibition of cell wall synthesis

• inhibition of protein synthesis

• inhibition of nucleic acid synthesis

• disruption of cell membrane

• inhibition of metabolic activity

successful pathogen

1. survive passage

2. attach to host tissue

3. withstand defense mechanisms

4. induce damage to host

exit of microorganisms from the host

• speech, breathing, coughing, sneezing

• mucous, saliva

• skin

• feces

• urine

• vaginal secretions

• arthropods, blood transfusions, needles

• milk

route of transmission and entry of microorganisms into the host

• airborne transmission

• mouth

• bites

• contact (direct or indirect)

• endogenous spread