Micribiology Exam 3

an organism that harbors another organism

association between 2 (or more) species (meaning "living together")

both members of the assocition benefit from the relationship

one benefits and the other one neither benefits nor is harmed

parasite benefits from the relationship while the host is harmed by it

both species harm each other wihout either benifitting

some species of organisms that do not usually cause disease but do so under certain conditions

microorganisms are present on inaminate objects or on surfaces of the skin or mucous membranes of the host, some with a capacityto invade host tissues

multiplication of any parasitic organism within or on the host's body

type of infection that used to refer to presence of large parasites in or on the body

occurs when an infection disrupts the normal functioning of the host

• capacity to produce disease
• depends on the ability of the organism to invade a host, multiply in the host, and aoid being damaged by the host's defenses
• the larger the number of pathogens, the greater the chances of causing disease

• refers to intensiyt of the disease (how hard it hits) produced by pathogens, and it varies among different microbial species and even among members of the same species of pathogen
• virulence of a pathogen can increase by animal passage, the rapid transfer of the pathogen through animals of a species susceptible to infection by that pathogen
• can be decreased by attenuation

can be achieved by repeated subculturing on lab media or by transposal of virulence

• lab technique in which a pathogen is passed from its normal host to a new host species and then passed sequentially through many individuals of the new species
• eventually the pathogen adapts completely to the new host and is no longer virulent for the original host
• used in mumps, measles vaccin preparation

• organisms that live on or in the body but do not cause disease
• also known as microbiota
• most are commensals

• comprose of microbes that are always present on or in the human body
• highly adapted to prevailing conditions

• comprise of microbes that can be present under certain conditions in any of the locations where resident microflora are found
• persis for hours to months depending upon the existing conditions (favorable)
• among the residen and transient micrlora, you can find some species that do nt usually cause disease, but can do so under certain conditions (opportunists)

• specific causative agent must be observed
• agent must be isolated and grown in pure culture
• hosts must get the same disease when inoculated
• agent must be re-isolated and show to be the same causative agent

• also known as nosocomial infections
• caused by infections acquired at hospital
• staphylococcus aereus infection

cause is unknown

• structural or physiolgocal characteristics that help organisms cause infection and disease
• pili for adhesion to cells and tissue
• enzymes that eitehr help in evading host defenses or protect the organism from host defenses
• toxins that can directly cause disease

specialized communities (colonies) of bacteria that utilize mass-produced glycocalyx to adhere to surfaces and bild a hospitable environment

• adherence
• host defense evasion

• structures made of glycocalyx that surround the bacterial cell
• hydrophobic nature protect the bacterial cell against harsh environments
• can resist phagocytosis

• enzymes that clot blood plasma
• can produce favorable environmentfor pathogen
• can hinder mobility of leukocytes

enzyme taht oxidizes hyaluronic acid, decreasing its viscosity and enabling the pathogen to penetrate deeper into the tissue

enzymes that kill RBCs and release Fe²⁺

enzymes that kill leukocytes

interfere with the ability of leukocytes to engulf microorganisms that secrete the exotoxin

enzymes that break down interleukins

• Direct- by release of toxins
• Indirecty

• toxins released from the pathogen at death, usually as a result of phagocytosis or degradation
• bacterial endotoxins have nonspecific effects
• can also cause tissue damage

created when acid-fast bacteria are degraded

endotoxin that is crated when gram-negative bacteria are degraded

• powerful toxins deliberately released by living pathogen (almost all gram-positive and some gram-negative), most are polypeptides
• C. difficile's TcdA, B. anthracis' toxin complex, and C. botulinum's Botulinum toxin (bottom)
• many have special attraction for special tissue
• Enterotoxins

• also known as autoimmune response
• can cause damage to the host by overreaction or missing the target enirely

• usually by nutrient acquisition by the pathogen
• pathogen out-competes host for nutrition

• characteristic of a disease that can be observed by examining a patient
• include such things as swelling, redness, rashes, coughin, pus formation, runny nose, fever, vomiting and diarrhea

• characteristic of a disease that can be felt or experienced only bt the patien
• include such things as pain, shortness of breath, nausea, sore throat, headache and malaise (discomfort)

Combo of signs and symptoms that occur together and are indicative of a particular disease or abnormal condition

after effects that some diseases leave even after recover (eg. effects following infection by polio virus)

study of factors and mechanisms involved in the frequency and spread of diseases and other health related problems within population of humans, animals or even plants

refers to the causation of a disease

number of new cases contracted within a set population during a specific period of time

total number of people infected withina a population at any time

rate typically expressed as the number of cases (individuals) per 100k people/year infected by the same disease or pathogen

rate typically expressed in terms of individuals/100k that have been killed by some disease or pathogen

infectious agent is present continually in the population of a particular geographic area, but both the humber of reported cases and the severity of the diesease remain low to constitute public health problem

• arises when a disease suddenly has a higher-than-normal incidence in a population
• then the moribity rate or motrtality rate of both become high enough to cause public health problem

occurs when an epidemic spread world wide

occurs in a random, unpredictable manner, involving several isolated cases that pose no great threat to the population as a whole

epidemic that arises from contact with contaminated substances

• arises from direct person-to-person contacts of horizontal transmission
• pathogen movies from infected to uninfected individual

• Human
• Animal
• Non-living, soil, and water

• Direct contact
• Indirect contact by fomites
• Droplets

• Waterborne
• Airborne, including dust particles
• Foodborne

• mechanical (on insect bodies)
• Biological

• disease cycles
• herd immunity

• Isolation
• Quarantine
• large-scale immunization
• vector control

• infectious diseases that are potentially harmful to the public's health
• Nationally Notifiable Infectious Diseases

caused by organisms that enter the patient from the environment

caused by opportunists among the patient's own microflora

• susceptibility
• transmission
• universal precautions