Microbiology Chapter 14 & 15

secondary infection

an opportunistic pathogen that takes advantage of a weakened immune system

vectors

animals that carry and transmit pathogens

communicable disease

any infectious disease that can be spread from one host to another

disease

homeostatic imbalance -state away from health

nosocomial infections

hospital acquired infections

pathogenesis

how a disease develops in a population

classifying infectious diseases

how they spread from one host to another, frequency of occurrence, severity & duration, extent of host involvement, state of host resistance

contagious disease

infectious diseases that are easily spread, usually in the air, from host to host

transmission

methods by which a pathogen goes from its source to a host

systemic (generalized) infection

microorganisms (or their products) are carried throughout the body by blood or lymph

indirect contact transmission

pathogens are carried on a NON-LIVING INANIMATE OBJECT (fomite) between one person and another

carriers

people who harbor pathogens but do not exhibit any symptoms or signs, yet can transmit the pathogen to others

skin, mucous membranes, parenteral route

preferred portals of entry (specific portals of entry)

period of convalescence

recovery has occurred, body returns to its pre-diseased state

pathophysiology

structural and functional changes caused by the disease

adhesins (ligands)

surface molecules (lipoproteins, glycoproteins) in the pathogen that attach to specific molecules on the cell membrane of host cells called receptors

pathogenicity

the ability of a disease-causing microorganism to overcome (evade) the host's defenses (immune system) AND cause disease

adherence

the ability of the microorganism to attach to a host cell

microbial antagonism (competitive exclusion)

the ability of the normal microbiota to prevent pathogens from establishing themselves

Staph. aureus, E. Coli, and P. aeuriginosa

the big three nosocomial infections in hospitals

etiology

the cause of the disease

virulence

the degree of pathogenicity (how easily the pathogen can overcome the host's immune system)

local infection

the disease-causing agent is contained in a relatively small area of the body

latent disease

the disease-causing agent is dormant (inactive) for years, then becomes active to produce the disease

incubation period

the first period, follows infections, but no symptoms are felt and no signs are seem

period of decline

the hosts immune system begins to overcome the infection and the symptoms and signs subside (weaken) *secondary infections can occur

primary infection

the initial infection a person gets, usually acute and viral the host's immune system is weakened by fighting off this infection

infection

the invasion and colonization of the body by disease-causing organisms

portal of entry, adherence, penetration of host's defenses, damage to host tissues

the microbial mechanisms of pathogenicity

human reservoir

the most important living reservoir of human pathogens

the third step in Koch's postulates

the pathogen from the pure culture must cause the same disease when it is inoculated into a healthy, susceptible laboratory animal

the second step in Koch's postulates

the pathogen must be isolated from the diseased host and grown in pure culture

the fourth and final step in Koch's postulates

the pathogen must be isolated from the inoculated animal and must be shown to be the original organism

bacteremia

the presence of bacteria in blood

toxemia

the presence of microbial-produced poisons in blood

septicemia

the presence of pathogens (ex. bacteria in blood), actively multiplying

viremia

the presence of viral particles in blood

the first step in Koch's postulates

the same pathogen must be present in every case of the disease

pathology

the scientific study of diseases

prodromal period

the second period, a very short period (if at all) following incubation, in which patient feels mild, general symptoms (fatigue, aches, malaise)

reservoir

the source of infection (pathogens)

period of illness

the third period, the symptoms and signs are at their strongest

opportunistic pathogens

those normal microbiota that NOW can, and will cause infection and disease

contact transmission, vehicle transmission, vector transmission

types of transmission

cholera

vibrio, waterbourne, Gram negative bacteria

cell wall components

waxy cell walls of Mycobacterium

pandemic disease

worldwide epidemic disease

arthropods

"joint-footed" animals that are the most important and largest group of vectors - insects

normal microbiota

(residents, normal flora), those microorganisms normally found in and on the human body, and which under normal conditions do not cause infection and disease *always present *in huge numbers

skin

*portal of entry -largest organ of the body in terms of surface area, an important defense against diseases -unbroken _______ is impenetrable by most microorganisms -physical barrier (epidermis; keratin is a waterproof protein), chemical barrier (pH is 5-6, fatty acids are toxic), and a biological barrier (dendrtitic macrophage WBC) -- nonspecific immune functions -diseases include scalded skin syndrome, boils, carbuncles, ringworm, necrotizing fascitis

parenteral route

*portal of entry -microorganisms are deposited usually by bites, cuts, punctures, injections, splits (skin) in tissues beneath the skin (or mucous membranes) -diseases include tetanus

mucous membranes

*portal of entry -soft, most tissues open to the external environment -physical barrier, chemical barrier (viscous, sticky mucus catches microbes, also contains lysozyme, IGA antibodies, cili action removes this bacteria-laden mucus) -diseases include pneumonia, anthrax, plague, cholera, typhoid fever, salmonella, staphylococcal food poisoning

facts about nosocomial infections

-these infections are not evident or incubated at the time of admission to the hospital -due to some invasive procedure that bypasses skin, mucous membranes -or an exposure to a host with a weakened immune system due to opportunistic pathogens -source: doctors, nurses, healthcare workers -transmitted by either direct or indirect contact transmission by fomite -8th leading cause of death in USA

WASH YOUR HANDS

CDC says the most effective way to prevent nosocomial infections is to...

if it's contaminated with organic material

How can water be a nonliving reservoir?

signs

OBJECTIVE changes a doctor, nurse, healthcare worker can see and measure (temperature, blood pressure, WBC count, rash, swelling)

symptoms

SUBJECTIVE changes a patient feels (pain, fatigue, nausea, malaise [feeling of uneasiness])

a) introduced into regions of the body where they are not normally found b) a weakened (compromised) immune system

The normal microbiota can and will cause infection and disease if:

microorganisms in the hospital environment, compromised host, chain of transmission

What is needed to be a nosocomial infection?

mechanical transmission

a PASSIVE vector transmission - the insect (ex. fly) lands on untreated sewage, carries pathogens on their feet and mouth parts. then the vector flies and lands on food which is ingested by the host

noncommunicable disease

a disease that cannot be spread from one host to another (ex. tetanus)

acute disease

a disease that develops quickly, very strong symptoms, lasts a short time

chronic disease

a disease that develops slowly, starts with mild symptoms, but over time, the symptoms and signs worsen - long term

endemic disease

a disease that is constantly present within a population

epidemic disease

a disease that many people, in a short time, in a given area, contact

sporadic disease

a disease that occurs only rarely, usually as an isolated incident

pathogen

a disease-causing microorganism

vehicle transmission

a medium (water, food, body fluids, air) carries and transmits pathogens

symbiosis

a relationship between two organisms; at least one must benefit

epidemiology

a science that studies the cause of a disease; its source and how it goes from its source to a host

Koch's postulates

a series of 4 experimental steps that links a suspected pathogen to a specific disease

droplet transmission

a type of contact transmission - mucus droplets from talking, sneezing, coughing, etc. traveling LESS THAN 1 meter

mutualism

a type of symbiosis - both organisms benefit (ex. us & our normal microbiota)

parasitism

a type of symbiosis - one organism benefits, and the other is harmed (ex. us & pathogens/opportunistic pathogens)

commensalism

a type of symbiosis - one organism benefits; other is unaffected (ex. us & some normal microbiota)

airborne transmission

a type of vehicle transmission - pathogens in dust nuclei are suspended in the air and travel MORE THAN 1 meter

foodborne transmission

a type of vehicle transmission - unsanitary handling of food, unfavorable storage (ex. temperature)

waterborne transmission

a type of vehicle transmission - via fecal-oral route

bloodborne transmission

a type of vehicle transmission through the blood

criteria to be a reservoir

a) a continual source of the pathogen b) must supply all the requirements for growth c) must have opportunity for transmission

examples of microbial antagonism

a) outcompetes for food (nutrients) and room b) alters conditions where they are (pH, oxygen levels) that affect other microorganisms c) E. Coli produces antibacterial proteins called bacteriocins that inhibit other microbes

exceptions to Koch's Postulates

a) some microorganisms have never been grown on artificial media b) some disease conditions (pneumonia, meningitis, peritonitis) can be caused by more than one pathogen c) some pathogens (Staph. aureus, Strep. pyogenes, Mycobacterium tuberculosis) can cause more than one different disease d) some pathogens only have humans as their host

infectious disease

diseases caused by pathogens (or their products)

zoonoses

diseases people can get from animals/animal products (wild and domestic)

focal infection

agents from a local infection are carried (by blood, lymph) to create other local infections

direct contact transmission

aka person to person contact transmission; direct physical contact between one person and another. there is no object between the two people

syndrome

all the symptoms and signs of a specific disease

capsules

allows the bacteria to resist phagocytosis

biological transmission

an ACTIVE, more complex form of vector transmission - vector first bites an infected animal, ingests blood. the pathogen reproduces in the gut or salivary glands of the vector. then the vector bites a host (person) and infects them with the pathogen

John Snow

father of epidemiology, picture of Broad Street, cholera epidemic

M-protein

component of the cell walls (& fimbriae) of Strep. pyogenes functions (in part) for the attachment of a host cell

penetrating host's defenses

evade (overcome) the immune system of the host

direct contact, indirect contact, droplet transmission

examples of contact transmission

human reservoir, animal reservoir

examples of living reservoirs

water, soil, food

examples of nonliving reservoirs

mechanical, biological

examples of vector transmission

water, food, air, blood

examples of vehicle transmission

coagulases

exoenzymes (ex. Staph. aureus) that coagulates blood, forms blood clots to isolate, wall itself off from host immune system - local infections

kinases

exoenzymes that dissolves blood clots made by the host's immune system to isolate and contain an infection

enzymes

exoenzymes, a major way pathogens evade the host's immune system *many damage host cells, tissues, and create the signs of a disease