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the entry and multiplication of an organism(infectious agent) in a host; are usually infectious or communicapable


infectious agent; if is present in a host, it does not mean that infection will occur


if a microoganism is present or invades a host, grows and/or multiplies but does not cause infection


may not pose a risk for transmission (passing from one person to another) ex: viral meningitis & pneumonia

communicable disease

transmitted directly from one person to another


if the pathogens multiply and cause clinical signs & symptoms


if clinical signs and symptoms are not present

chain of infection

infection occurs in a cycle and depends on the presence of ALL of the following: 1)An infectious agent or pathogen 2)a reservoir or source for pathogen growth 3)a portal of exit from the reservoir 4)a mode of transmission 5)a portal of entry to a host 6)a susceptible host...... infection can develop if this chain is not interrupted

resident organisms

permanent residents of the skin, where they survive and multiply without causing illness, major part of the bodys protection

resident flora

covers the entire exterior of the body; protects agianst pathogens, imortant to retain and maintain

transient microorganisms

attach to the skin when a person has contact with another person during normal activites; attach loosely to skin in dirt and grease or underneath fingernails

the potential for microorganisms to cause disease depends on:

1)sufficient number of organisms (dose) 2)Virulence 3)ability to enter and survive in the 4)susceptibility of the host (host resistance)


ability to survive in the host or outside the body


has an impaired immune system


a place where a pathogen can survive but may or maynot multiply


persons who show no symptoms of illness but who have pathogens on or in their bodies that can be transferred to others


microorgansims require nourishment


required by aerobic bacteria for survival and for multiplication sufficient to cause disease; cause more infections in humans than anaerobic


strive where little or no oxygen is available; infections deep in pleural cavity, in ajoint, or in deep sinus


are required by most organisms for survival; usually the most frequent place for microorganisms


is important because it influences where microorgansims live; usually is around 20 to 43 C (68F to 109F) where they grow best


determines the viability of microorganisms; usually ranges from 5 to 7


usually the thrive in dark environments; such as under dressings and within body cavities

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