68 terms

Micro-Lesson 11

living organism that transmits infectious agen from 1 host to another, most are biting or blood sucking insects, malaria-mosquitos, ticks-RMSF
Portal of entry
how MO gets into host, mouth, nose, vagina, penis, wound
Oppurtunistic MO
MO takes advantage of the situation or opportunity that it normally does not have to cause a disease
Clostridium difficile, Staph aureus in surgical wound infection
interaction of 2 or more species in some ongoing way
infection found in animals but naturally transmitted to humans, rabies, anthrax, plague
Typhoid Mary
-Mary Mallon was the 1st known healthy carrier or typhoid fever
-Worked as a cook. As a result, infected hundreds of people
-Vehemently denied she was the cause of illness
-Was quarantined
-Upon her death, autopsy revealed gallbladder to be filled with typhoid-causing bacteria
Human Habitat
Idea Habitat for MO because of good source of nutrients and moisture, stable pH, right temperature, and large surface area on which to settle
Normal Resident Flora
large, mixed population of MO adapted to our body, generally good for us, everyone has a different resident flora
About 100 trillon MO
Largest in colon and gums in mouth, one trillion MO/gram
Skin 100,000 MO/gram
Nose 10,000 MO/gram
Also a wide diversity of MO
500 different in human feces
200 different MO in mouth
MO may be bacteria, fungi, protozoan
Helpful in many ways, Vitamin K in intestines, competition for nutrients
Colonized at birth
Transient Flora
MO on or in body for a short time, passing through
Skin as a Habitat
Largest organ system in body
MO usually on surface and epidermis, intact
Staph Aureus, Staph Epi, fungi
Respiratory Tract as a Habitat
MO in upper respiratory tract
Should NOT find MO in lower tract
Most MO filtered out by nasal hairs
Staph, Haemophilus, Neisseria
GI Tract as a Habitat
MO from mouth to anus
Few MO in esophagus and stomach
Many MO important
E.Coli, Enterobacter, Closteridium, Citrobacater
Urogenital Tract as a Habitat
MO mostly outer surfaces of penis and vagina
May find MO in lower urogenital tract
Should NOT find MO in upper tract
Strep, Coliforms, Staph
Where you should not find MO in Human Body
Blood, Spinal Fluid, Synovial Fluid, Urine
anything that houses a MO, plants, animals, insects, human
MO that is capable of causing a disease
Salmonella and Corynebacterium
MO that does not cause a disease
Micrococcus luteus
potency of pathogen, how powerful is pathogen, 4 classes
Class 1 Virulence
low virulence, not know to cause a disease
Micrococcus luteus
Class 2 Virulence
moderate risk to cause a disease
Staph aureua
Class 3 Virulence
MO readily transmitted and virulent
Mycobacterium tuberculosis
Class 4 Virulence
deadliest of the MOs
Ebola, Marburg virus, Lassa Fever, Rabies
Need bio containment facilities to work with Class 4 MO
Low Virulence
high numbers-disease
High Virulence
low numbers
Ebola, and Tularemia
development sequence a disease goes through, transmission, entrance, incubation, symptoms, prognosis
occurs when MO overcomes body's defenses and lives inside host, may or may not cause tissue damage
conditions where host's tissues are damaged or function is altered
Clinical Infection
signs or symptoms of disease are seen: fever, redness, swelling, open wounds
Subclinical Infection
no apparent signs or symptoms seen, most dangerous stage of disease
host with clinical or subclinical infection who carries disease from one location to another
Typhoid Mary
MO established on body surface
Acute Infection
infection that comes on rapidly, with severe but short-lived side effects
Flu and common cold
Chronic Infection
infection that progesses and persists over a long period of time
TB and syphilis
Sub-Acute Infection
infection that does not come on as rapidly as acute infections or persist as long as chronic ones
Walking pneumonia
Secondary Infection
infection that compounds a preexisting infection
Mixed Infection
several MO establish themselves simultaneously at infection site
Staph & Strep-infection of the mouth
Baterialremia & Viralremia
small numbers of bacterial/virus in the blood but not necessarily multiplying
MO are multiplying in the blood and are present in large numbers
primary habitat in the natural world from which a pathogen originates
insects, animals, soil, water, rabies-bats, water-cholera, plague-rats
relationship that is helpful to organism but causes no damage to the host
relationship that is beneficial to both host and organism
bacteria in stomach of termite
organism lives in or on host and gets its livelihood from host and causes harm to host
tapeworm, roundworm in GI tract
Comprimised host
host whose natural defense mechanisms are impaired or suppressed, medical treatment (radiation treatment), stress, other illness (flu followed by pneumonia) inborn errors of metabolism
Contagious Disease
the ability of a pathogen to multiply in host, exit from host, be transmitted to 1 or more secondary host, enter and cause a disease in the secondary host, sometimes called communicable disease
5 Routes of Transmission & Entry of MO into Host
Airborne Spread
Common Vehicle Spread
Vector Borne Spread-Mechanical or Biting
Contact-Direct, Indirect, Droplet, Fecal Oral Route
Endogenous-self spread
Airborne Spread
Spread of MO over a distance of more than several feet between the source and the victim, Anthrax
MO contained in very tiny droplets, may stay suspended for hours or days
Laughing, Coughing, Singing, Shouting, Talking, Spiting, Sneezing, anything propelling out of the mouth
Common Vehicle Spread
Contaminated inanimate vehicle acts as a means of transmitting MO to several people
Glass, cups, knives, spoon, forks, any objects that can be placed in mouth
Vector Borne Spread
Mechanical spread of MO on hairs on insects to inanimate objects, food, people
Most insects are very hairy creatures
Biting transfer by blood sucking insects or by biting animals to other hosts
Mosquitos, ticks, fleas, dogs, raccoons, skunks, bats
Contact Spread
Prospective host must have actual contact with the source of the MO and the primary host
Direct Contact
person to person spread, actual physical contact, syphilis, gonorrhea, HIV, kissing, touching, sexual contact, handshaking
Indirect Contact
Passive spread of MO through an intermediated object, doorknob, light switch, elevator button
Droplet Spread
airborne spread of MO when source and victim are relatively close to each other, in your face, sneezing, coughing, talking
Fecal Oral Route Transmission
Inadequate personal hygiene after defecation, unclean drinking water, salad bars, sandwich bars, may be direct or indirect
To be a successful pathogen MO must do 4 things (Possible Discussion Question)
1. Survive passage from 1 host to another host or from reservoir to host, animal, direct contact, environmental conditions-hot/cold
2. Attach or penetrate into host's tissue, abrasions, injection, ingestion, incision, scrapes, cuts, catherizations
3. Withstand host's defense mechanisms-1st line of defense (external mechanisms), 2nd line of defense (internal mechanisms), 3rd line of defense (immunity)
4. Induce damage to or malfunction of host's tissues, toxins, damaging neural muscular junctions, pneumonia in lungs
MO Pathogenicity
Attachment, Receptor sites not full, Fimbriae, Capsules, Spikes, Hooks, Filament
Circumvention of defense mechanisms
capsules, inhibits phagocytosis, Leukocidin destroys WBC
Hyaluronic acids
destroys tissue cement
dissolves blood clots
destroys collagen in bone, muscles, and cartilage
destroy RBC
inhibits phagocytosis by putting fibrin on cell wall of MO
tissue damage or malfunction of tissue
Stimulation of Vigorous Inflammatory Response
response that changes function of host cells
Strept. pneumona for TB forming scar tissues in lung
Secretion of enzymes by MO
collagenase, hemolysins, lipases, nucleases, etc.
toxins released into surrounding environment when MO dies, less potent, larger amounts of toxins need to cause problems such as fever, diarrhea, hemorrhage, circulatory problems
toxins released into surrounding environment as soon as the toxin is made, some of the most powerful toxins known, damages cell membrane and lysis of cell, only need small amounts of toxin to cause damage
Host Factors of Diseases (Possible Discussion Question)
Delicate balance between bost's various defence mechanisms and the virulence factors of the MO
If the host's defense mechanisms are good, there is less chance of getting a disease
If the MO virulent factors are higher than host's defense mechanisms, good chance of getting a disease