part 1 spcon module 5

● Microbes

● Organisms that exist as unicellular, multicellular, or cell clusters

● Widespread in nature

● Beneficial to life but some can cause serious harm

● Different types/families

● E.g. Virus, bacteria, mycoplasma, ricketssiae, chlamydia, protozoa, fungi, helminths

WHAT ARE MICROORGANISMS? ●

○ Provided the basis for identification and classification

○ Permits diagnosis of a specific pathogen in specimens of body fluid, secretions or exudates

○ Ways to interfere with the mechanism of transmission

● INTRINSIC PROPERTIES:

● Unicellular

● Prokaryotic

● Well-defined cell wall

● Grow independent on artificial media without need for other cells

BACTERIA

BACTERIA CLASSIFIED ACCORDING TO SHAPE:

● _____: Spherical

● _____: Rod-shaped

● _____: Spiral

● _____: Curved

BACTERIA CLASSIFIED ACCORDING TO SHAPE:

● COCCI: Spherical

● BACILLI: Rod-shaped

● SPIRILLA/SPIROCHETES: Spiral

● VIBRIO: Curved

BACTERIA CLASSIFIED ACCORDING TO RESPONSE TO STAIN (CELL WALL COMPOSITION):

● _____

○ Single outer membrane with thick peptidoglycan

● _____

○ Thin layer of peptidoglycan between two outer membrane

BACTERIA CLASSIFIED ACCORDING TO RESPONSE TO STAIN (CELL WALL COMPOSITION):

● GRAM POSITIVE STAINS PURPLE

○ Single outer membrane with thick peptidoglycan

● GRAM NEGATIVE STAINS PINK

○ Thin layer of peptidoglycan between two outer membrane

BACTERIA CLASSIFIED ACCORDING TO RESPONSE TO STAIN (CELL WALL COMPOSITION):

● _____

○ Single outer membrane with thick peptidoglycan

● GRAM POSITIVE STAINS PURPLE

BACTERIA CLASSIFIED ACCORDING TO RESPONSE TO STAIN (CELL WALL COMPOSITION):

● _____

○ Thin layer of peptidoglycan between two outer membrane

● GRAM NEGATIVE STAINS PINK

What is this

● Unusual self-replicating bacteria

● No cell wall component with small genomes

● Limited antibiotic effect but sensitive to some

● Requires a strict dependence on the host for nutrition and sustenance

MYCOPLASMA

What is this

● Primarily ANIMAL PATHOGENS

● Produce disease in humans through bite of an insect vector

○ (E.g. Tick, flea, louse, mite)

● Gram negative obligate intracellular organism

● Causes life-threatening infections

● Requires a host for replication

● No human to human transmission

● Coxiella, Bartonella, Rickettsiae

RICKETSSIAE

What is this

● Organism made up of RNA and DNA NUCLEUS

● Smallest known organism

● OBLIGATE PARASITE (Dependent on host cells)

● Cannot replicate unless they invade the host cell

● MEANS OF TRANSMISSION:

○ Respiratory

○ Fecal oral route

○ Sexual contact

● Not susceptible to antibiotics

● Antiviral medication serves as to mitigate the spread

● CLASSIFIED ACCORDING TO SHAPE:

○ Rods: Filaments

○ Spheres

○ Icosahedral polygon

VIRUSES

What do you call when a virus is dependent on host cellsa

OBLIGATE PARASITE

VIRUS CLASSIFIED ACCORDING TO SHAPE

○ Rods: Filaments

○ Spheres

○ Icosahedral polygon

What is this

● Single cell unit of non-differentiated cells

● Eukaryotes

● Have cell membrane, not cell wall

● Nuclei are surrounded by a nuclear membrane

● Larger parasites (Hookworms, roundworms)

● Amoeba

PROTOZOA

What is this

● Unicellular filamentous organism

● Eukaryotes

● Surrounded with cell wall

● Possess hyphae (Filamentous outgrowth)

● Occurs as yeast or molds

● Fungal diseases in humans are called MYCOSES

○ Patients are usually immunocompromised

FUNGI

● Fungal diseases in humans are called

MYCOSES

What is this

● Sequence of events for infection to occur

1. Begins with transmission of a PATHOGEN to the HOST (Depends on the pathogenic agent)

1. RESERVOIR

2. PORTAL OF EXIT from the reservoir

3. Mode (mechanism) of TRANSMISSION

4. PORTAL OF ENTRY into the host

5. SUSCEPTIBLE HOST

● PATHOGEN → RESERVOIR → PORTAL OF EXIT → TRANSMISSION → MODE OF ENTRY → HOST

CHAIN OF TRANSMISSION:

What is this

● Microorganism that has the capacity to cause disease

● They stimulate a disease response

● May harm the host

● Its ability to stimulate an immune response in the host (ANTIGENICITY) greatly varies

● DEPENDS ON:

○ Site of invasion

○ Number of pathogens

○ Dissemination in the body

● Immune status of a person plays the largest role in determining the risk for infection

PATHOGENS

What do you call the ability of the pathogen to stimulate an immune response in the host

ANTIGENICITY

Enumerate the terms under pathogen

VIRUS INVADES CELLS

Principal Pathogen

Opportunistic Pathogen

Pathogenicity

Virulence

Under pathogen what is this

○ Interfere with cellular metabolism, growth, and replication

○ Alter antigenicity

○ Causes gene rearrangement ○ Latent infection

○ Destroy helper T cells

● BACTERIA

○ Secretes antigenic water-soluble exotoxins that easily disseminates in the blood

● VIRUS INVADES CELLS

Under pathogen what is this

● Cause a disease in an intact defense mechanism

PRINCIPAL PATHOGEN:

Under pathogen what is this

● Do not cause a disease with intact host defense mechanism but causes devastating disease in hospitalized or immunocompromised persons

OPPORTUNISTIC PATHOGEN:

Under pathogen what is this

● The ability of the organism to induce disease

● Depends on the organism’s speed of reproduction in the host and the extent of damage to the tissues

● The strength of toxin released by the pathogen

PATHOGENICITY

Under pathogen what is this

● Refers to the potency of the pathogen in producing severe disease

● Provides a quantitative measure of pathogenicity

● Measured by fatality

VIRULENCE:

What is this

● An environment in which an organism can live and multiply

● Human, animal, plant, soil, food

● Provides the essentials for survival of the organism at specific stages in its life cycle

● Human and animal reservoirs can be symptomatic or asymptomatic carriers of the pathogen

● CARRIER

○ Maintains an environment that promotes growth, multiplication, and shedding of the parasite without exhibiting signs of disease

RESERVOIR

Under reservoir what is this

○ Maintains an environment that promotes growth, multiplication, and shedding of the parasite without exhibiting signs of disease

● CARRIER

What is this

● The place from which the parasite leaves the reservoir

● In general, this is the site of growth of the organism and corresponds to the system of entry into the next host

● E.g.

○ GI PARASITES:

■ Portal of exit through feces

■ Portal of entry to new host is mouth

○ HOOKWORMS:

■ Portal of exit through feces

■ Portal of entry to new host through skin

● Walking barefoot in soil

● Common portals of exit include secretions and fluids

○ Respiratory secretions, blood, vaginal secretions, semen, tears, excretions such as urine and feces

○ Open lesions and exudates such as pus

● Knowledge is essential for preventing transmission of a pathogen

PORTAL OF EXIT

Under portal of exit what is this

■ Portal of exit through feces

■ Portal of entry to new host is mouth

○ GI PARASITES:

Under portal of exit what is this

■ Portal of exit through feces

■ Portal of entry to new host through skin

● Walking barefoot in soil

○ HOOKWORMS:

Under contact transmission what is this

● Direct transfer of an organism that comes into physical contact

○ Skin to skin

○ Mucous membrane to mucous membrane

● E.g. Kissing, touching, biting, sexual contact

DIRECT CONTACT:

Under contact transmission what is this

● Transfer of organism from an infected source to a host by a passive transfer from an inanimate or intermediate object (Fomite)

○ E.g. telephones, bedside rails, countertops, tables

● Contaminated needle (Needle prick)

● Fecal oral transmission

○ Ingestion of an enteric pathogen from a food prepared by an infected person who did not wash hands prior to serving

INDIRECT CONTACT:

What mode of transmission is this

● Occurs when disease-causing organisms are so small

○ Less than 5 microns

● Organisms are capable of floating air currents within a room

● Can remain suspended in the air for several hours

● Often propelled from the respiratory tract through COUGHING or SNEEZING

● Host inhales the particles directly into the respiratory tract

● E.g. Tuberculosis, chicken pox, rubeola measles

AIRBORNE TRANSMISSION

What mode of transmission is this

● Differs from airborne transmission because droplets are larger particles than airborne particles

○ >5 microns

● Do not remain suspended in air but fall out within 3 feet of the source

● Produced when a person coughs or sneezes then travel only a short distance

● E.g. influenza, coronavirus

● People in closest proximity to the infected source have the highest risk for infection

DROPLET TRANSMISSION

What mode of transmission is this

● Occurs when infectious organisms are transmitted through a common source

○ E.g. Contaminated food, water, intravenous fluids

● Salmonella, Amoeba

VEHICLE TRANSMISSION

What mode of transmission is this

● Infectious organisms involves insects

● Animals that act as intermediaries between two or more hosts

● Lyme disease and Rocky Mountain Spotted Fever

● Japanese Encephalitis: Common in Philippines

○ From mosquitoes

VECTOR-BORNE TRANSMISSION

What is this

● Lyme disease and Rocky Mountain Spotted Fever

● Japanese Encephalitis: Common in Philippines

○ From mosquitoes

What is this

● Each person varies with own

● FACTORS INFLUENCING HOST’S SUSCEPTIBILITY:

○ Age and sex

○ Hereditary

○ General health

○ Diet and nutritional status

○ Hormonal balance

○ Presence of concurrent disease

○ Drug use

○ Hygienic practices

○ Sexual practices

● Presence of anatomic and physiologic defenses

○ Line of defenses

HOST SUSCEPTIBILITY:

What is this

1ST LINE OF DEFENSE

What is this

2nd and 3rd line of defense