Microbiology - Biology 221 - Exam 2 - Victor Valley College (VVC) - David Gibbs - Lecture 6: Infections and Disease

Symbiosis:

To live together

Types of Symbiosis:

- Mutualism
- Commensalism
- Parasitism (aka) Pathogen

Mutualism:

~ Both benefit (you and the bacteria)

Commensalism:

~ Live on you, but no harm or health

Parasitism (aka) Pathogen:

~ Hurt you; Cause Disease

Normal Flora:

~ Normal Bacteria
- Most are commensal
- Some are mutual
- Can be bacteria, fungi, and protozoa

How Norma Flora Become Opportunistic Pathogens:

- Immune suppression ~ of any kind (AIDS, Chemo, Common Cold, Alcohol...)
- Changes in the normal flora ~ Changes in the #s of normal flora (long term antibiotics)
- Normal flora into an unusual place (E. coli should be in intestines, should not be in bladder or UT)

Other Influences on normal flora:

- Hormonal changes (some hormones can make microbes reproduce)
- Diet changes

Infection:

- The movement of microbes into the host
- Exposure to microbes
> Contamination

([Infection] Contamination) Microbes not membranes of. . .

Normal flora

([Infection] [Contamination] Microbes) Get into the body by way of:

- Food and drink
- Air
- Sex
- Arthropods

Portals of Entry into the Host:

- Skin
- Mucous Membranes
- Placenta
- The parenteral route

(Portals of Entry into the Host) Skin:

- Outer layer is thick with dead cells that form a barrier
- Pathogens
> Enter skin by hair or sweat glands
> Abrasions, cuts and scrapes
> Parasitic worm larvae
> Fungi

(Portals of Entry into the Host) Mucous Membranes:

- Thin moist and alive

([Portals of Entry into the Host] Mucous Membranes) Easy portal of entry and more hospitable:

- Respiratory tract
- Urinary tract
- Reproductive tract
- Gastrointestinal tract
- Conjunctiva

(Portals of Entry into the Host) Placenta:

- Some pathogens can cross
> Spontaneous abortion
> Birth defects
> Premature birth

(Portals of Entry into the Host) The parenteral route:

- Puncture beneath the skin and mucous membranes (thrones, needles, dogs, cats, and insects)
- Happens by penetrating the skin

(IS: Introduction Slide)
Nature of infectious Disease:

- Disease
- Manifestation of disease
- Etiology

Disease:

- Known as morbidity
- Any change from a state of health

Manifestation of disease:

- Symptoms-subjective (only patient can feel)
- Signs-objective (Everyone can see)
- Syndromes are groups of signs and symptoms
- Asymptomatic or sub-clinical

Etiology:

- The cause disease
- Koch's postulates
- Nature of infectious Disease

Nature of infectious Disease:

- Pathogenicity
- Virulence

Pathogenicity:

The ability of an organism to cause a disease

Virulence:

The degree of pathogenicity

Patterns of infection:

- Localized infection
- Systemic infection
- Mixed infection
- Primary infection
- Secondary infection
- Acute
- Chronic
- Subacute

Localized infection:

~ One place

Systemic infection:

~ -->Blood - then to any other organs

Mixed infection:

~ More than one infectious microbe

Primary infection:

~ The first microbe to cause infection (cold + flu)

Secondary infection:

~ The growth of a second microbe (pneumonia)

Acute:

~ Comes on fast; lasts a short time

Chronic:

~ Comes on slow; lasts a long time

Subacute:

~ Between Chronic + Acute

Virulence Factors:

~ Factors that help make you sick
- Adhesion factors

(Virulence Factors) Adhesion Factors:

- To attach to the host (Pili + Fimbrae)

Types of adhesion factors:

~ Protozoa (suckers)
~ Worms (hooks + suckers)
~ Viruses use ligand
> Bind to specific receptors on cells
>> to bind + then enter the cell

Extracellular enzymes:

Degrade specific molecules to enable bacteria to invade deeper tissue

(Types of) Extracellular enzymes:

- Hyaluronidase
- Collagenase
- Coagulase
- Kinases
- Phospholipases (+ lipases)

~ Phospholipases:

~ Break membrane down and go through cells

~ Lipase:

~ Break down antibacterial lipids on skin

Toxins:

- Exotoxins-secreted by the organism (bacteria)
- Endotoxins-from the Gram-negative bacteria

Exotoxins:

- Cytotoxins~kill cells
- Neurotoxins~bind to neurons + stop their functions
- Enterotoxins~=Intestines (diarrhea, vomiting)

Endotoxins:

- Lipid A portion of the Lipopolysaccharide
>~ Comes from outer membrane Gram -
>~ Fever, shock, rash, Death

Antiphagocytic Properties:

- Capsules
> Made of carbs
> Inhibit the immune system
> > Big a slimy + stop phagocytosis
> > > Phagocytes cannot attach
> Some Capsules neutralize the enzymes in lysosomes
> > Even if pathogen is phagocytized
> > > (WBC) They cannot digest the pathogen
> > > > Bacteria reproduce + fill up the WBC
> > > > They carry the pathogen all over the body

(EC: Extra Credit)
The Five Stages of the Infection:

- Incubation period~From when someone sneeze on you until you get sick (~2 days)
- Prodromal period~When your getting sick
- Illness~When your sick
- Decline~When your starting to get better
- Convalescences~"tissue repair"; when you feel better

Reservoirs of Pathogenic Organisms:

- Animal reservoirs~Found only in animals
- Human reservoirs~Found only in humans
~ Nonliving reservoirs~Found only in nonliving reservoirs (dirt, food, water)

Transmission of Infectious Disease:

- Contact transmission
- Vehicle transmission
- Vector transmission

Contact transmission:

- Direct contact transmission~Person to person >~ Any kind of contact
- Indirect contact transmission~Fomites (phone, door)
> Fomites
> Droplet transmission~Drops of spit contain pathogens >~ Less then 1 meter

Vehicle transmission:

- Airborne transmission~Greater than 1 meter >~ *Dust; Spit; aerosals; Bacteria form a loop
- Waterborne~Drink >~ Fecal
- Food-borne transmission~Fecal

Vector transmission:

~ Something carries it from person to person
> ~ Insects + animals (ticks)

Epidemiology:

- Occurrence of disease-Incidence rate and the prevalence
- Geographic Distribution of Disease
- Hospital Epidemiology
- The spread of disease

Occurrence of disease-Incidence rate and the prevalence:

- Incidence= # of new cases/ # of people at risk*1000
- Prevalence= old cases+new cases/ # of people at risk

Geographic Distribution of Disease:

- Endemic~Going on in one location at the same rate all the time
- Sporadic~Few cases happen in different locations, but are not connected + just go away
- Epidemic~Big increase (Incidence rate) in a given location
- Pandemic~Epidemic all over the world

Hospital Epidemiology - Nosocomial Infections:

- Acquired in the hospital by patients
> Exogenous Infections
> Endogenous Infections
> Latrogenic Infections

Exogenous Infections:

~ From the health care facility
>~ dirty sheets

Endogenous Infections:

~ Patients own normal flora because of the treatment + because of chemo

Latrogenic Infections:

~ Dr. induced or procedure that went wrong

The spread of disease:

- Communicable disease~Disease you get from another person >~ Direct of indirect
- Contagious disease~This is a communicable disease that is easy to catch!
-Noncommunicable~Does not come from another person