INFECTION/PATHO (Ch 34)

Four stages to an infection cycle

Incubation period
Prodromal stage
Illness stage
Convalescent stage

Objective changes that can be observed and measured (rash, fever)

Signs

Subjective changes (pain, loss of appetite)

Symptoms

Set of characteristic signs and symptoms for a disease

Disease syndrome 

Pathogens employ _____ _____ to enter hosts, evade defenses, multiply, and transmit to new hosts

virulence factors

When the immune response to a pathogen causes major tissue and organ damage, contributing to the pathology and disease

Immunopathogenesis 

Organism that supports the survival and growth of a pathogenic organism

Host

A microbe growing and multiplying on or within a host, may or may not result in disease

Infection

Any change from a state of health caused by an infection

Infectious disease

Any organism that causes disease

Pathogen

Part of normal microbiota but causes disease when host is immunocompromised or following entry into unprotected sites

Opportunistic pathogen

Ability of a pathogen to cause disease

Pathogenicity

Degree of harm inflicted on a host

Virulence

__________ is ability to cause a disease, __________ is how bad that disease is

Pathogenicity
Virulence

Natural environmental location where the pathogen normally resides (animate or inanimate)

Reservoir

Organism that spreads disease from one host to another

Vector

Horizontal contact, vectors, vertical contact, and airborne droplets are all forms of ________ transmission

direct

Fomites, contaminated food/water, and long-distance air droplets are all forms of _____ transmission

Indirect

Infectious agents exit and enter through one or more ________ __ _____ that are best suited to their mechanism of pathogenesis

Portals of entry

Number of microbes required to cause disease in 50% of inoculated hosts

ID50

Dose that kills 50% of hosts within a specified period

LD50

Lower lethal dose = _______ virulence

higher

What are the two main categories of virulence factors?

Those that promote persistence
Those that damage the host

Any microbial factor that promotes attachment to host cells

Adhesin

Bacteria use adhesins, while viruses use _____ or envelope proteins to adhere to hosts

capsids

Factors that assist in invasion of the host can be either _____ or _______

active
passive

Factors that assist in invasion of host that are not related to the pathogen itself (e.g. skin lesions, wounds, insect bites, etc.) are

Passive

Factors that assist in invasion of host by producing lytic substances that alter host tissue are

Active

Virulence factors that cause damage to host cells are also called

toxins

Toxin that is secreted by various types of bacteria into the host environment; Kills cells or alters cell function

Endotoxin

Toxin that is not secreted, like a part of LPS of gram-negative bacteria; Can hyperactivate host immune system to harmful levels

Endotoxin

hairlike appendages that attach to specific host cells

Pili (fimbriae)

Pili that adheres to carbohydrates on host membranes

Type I

Type I pili grow from ____ membrane of gram-negative bacteria

Outer

Type I pili produce a ______ attachment to host cell

static

Pili involved in “twitching” motility

Type IV

Type IV pili produce a ______ attachment via assembly and disassembly

dynamic

Type IV pili grow from _______ membrane of many Gram-negative bacteria

Inner

Do endotoxins or exotoxins often travel from the site of infection to other body tissues, where they exert their effects? 

Exotoxins

AB toxins are a prime type of toxin for (endo-/exo)toxins

Exotoxins

The A subunit does:
The B subunit does:

In AB toxin systems

Catalyze reaction that causes toxicity

Binds to host-cell receptor

Many AB toxins modify host protein ____ and ____

structure
function

LPS is an endotoxin because it is bound to the bacterium and released when

the microbe is lysed 

Shiga toxin is a _____toxin that does what?

Exotoxin (AB)
Cleaves 28S rRNA in eukaryotic ribosomes; modifies protein outcome