Microbiology Exam 3 Study Guide

endogenous infection

caused by biota already in the body
can occur when normal biota is introduced to a site that was previously sterile

steptococcus penemonia

What is an example of an endogenous infection that can occur when a normal biota is introduced to a previously sterile site?

exogenous infection

origination from outside the body
environment, another person, animal

exotoxin

secreted by living bacterial cell to infected tiesues
many types
toxic in small amounts
specieific to cell type
simulates antitoxins

endotoxin

not actively secreted
lipopolysaccharide (LPS) sheds from outer membrane of gram negative bacteria, exclusively
toxic in high doses
fever
inflammation
systemic

signs of infection

objective evidence of disease as noted by observer
more precise than symptoms
ex: fever, abscess, etc.

symptoms

subjective evidence of dsease as sensed by patient
ex: malaise, chills, nausea, etc.

sequelae

long-term or permanent damage to organs and tissues

meningitis - deafness
strep throate - rheumatic heart disease
lyme disease - arthritic
polio - paralysis

What are some examples of pathogens and the sequela effects of that infection?

infectious dose (ID)

minimum number of microbes required for infection to proceed

• determined experimentally for many micorbes

• microbes with small infectious dose have greater virulence

• lower ID = higher infectivity

• higher ID = weaker pathogenicity

Florence Nightingale

first to collect and use health, disease, and death stats to improve public health
nurse during Crimean War
32/100 soldiers dying at field hospital mostly from dysentary, not gunshot wounds
implemented sanitary conditions of hospital → 2/100 died

Robert Koch

developed standard for determining causation of disease that stood test of scientific scrutiny
determined causative agent of anthrax

Koch’s Postulates

series of proofs that established classic criteria for etiologic studies

Molecular Koch’s Postulates

formulated to establish that a gene found in a pathogen contributes to disease-causing ability of organism

John Snow

doctor during London’s Soho neighborhood cholera epidemic (1854)
made map indicating cholera in area to represent the hypothesis that water from specific pump harbored cholera bacterium
town council removed pump and epidemic stopped
solved epidemic using case mapping

stratum corneum, outer layers, hair follicles, sweat glands

What are the four protective mechanisms of the skin?

stratum corneum

epithelial cells compacted, cemented together, and impregnated with keratin, forming a thick, tough, impervious, waterproof layer

outer layers

constantly shed off, taking associated microbes with them

hair follicles

hair shafts periodically extruded and follicle cells desquamated (shed off)

sweat glands

provide flushing effect that helps remove microbes

eosinophils

What blood cells are commonly present during parasitic infections and allergic reactions?

eisoniphils (white blood cells)

attracted to sites of parasitic infection and antigen-antibody reactions
play a major phagocytic role

neutrophils

What is a phagocytic white blood cell that is most numerous in the blood?

neutrophils

react early in inflammatory response to bacteria, foreign materials, and damaged tissue
- primary component of pus

high neutrophil count in blood

What is a common sign of bacterial infection?

thymus under influence of thymic hormones

Where do T cells (lymphocytes) mature?

specificity

What does T cells develop in the thymus?

designed to fight only one specific antigen

What does it mean when T cells are specific?

bone marrow in humans
bursa of fabricius in birds

When do B cells (lymphocytes) mature?

interferons

small proteins produced naturally by certain white blood cells and tissue cells
used in therapy against certain viral infections and cancer
involved in defenses against viruses and other microbes and in immune regulation and intercommunication
reduces cholesterol

alpha, beta, and gamma

What are the three major types of interferons?

alpha interferon

activates NK (natural killer) cells

beta interferon

plays role in maturation of B and T lymphocytes and in inflammation

gamma interferon

inhibits cancer cells, stimulates B lymphocytes, activates macrophages, enhances effectiveness of phagocytosis

complement cascade (when bacteria is involved)

consists of over 50 blood proteins that work together to destroy bacteria and certain viruses
a cascade reaction where 1st substance activates the next, continuing until the end product is reached

initiation
amplification and cascade
poymerization
attack

What are the four stages of the complement cascade?

membrane attack complex, forms ring-shaped proteins that digest holes in bacterial cell membranes, destroying them

What is the final product of the complement cascade?

classical complement pathway
lectin pathway
alternative pathway

What are the three pathways of the complement cascade?

antibodies bound to microbial surfaces

What is the classical complement pathway activated by?

lectins that bind to sugars on microbial surfaces

What is the lectin pathway activated by?

activated directly by repeated molecules on microbial surface, like LPS

What is the alternative pathway activated by?

acquiring specific immunity

the third adaptive line of immunity acquired after an immunizing event such as an infection

a product of B and T lymphocytes undergo a selective process that specializes them for reacting to only one specific marker

helper T cells

activate macrophages, assist B-cell processes, help activate cytotoxic T cells

cytotoxic T cells

lead to destruction of infected host cells and other “foreign” cells

regulatory T cells

control T-cell response by secreting anti-inflammatory cytokines or preventing proliferation

plasma cells

when activated by antigens, B cells divide → plasma cell: all have same reactive profile, release antibodies in tissue and blood
attach to antigen for which they are specific and mark it for destruction or neutralization

major histocompatibility complex (MHC)

set of genes that code for human cell markers, give rise to a series of glycoproteins called MHC molecules, plays a vital role in recognition of self by the immune system and in rejection of foreign tissue

human leukocyte antigen (HLA)

What are MHC molecules also called?

red blood cels

MHC molecules are found on all cells except:

immunoglobulin G (IgG)

long-term immunity, memory antibodies, neutralized toxins, opsonizes, fixes complement, crosses placenta

immunoglobulin A (IgA)

secretory antibody, on mucous membranes

immunoglobulin M (IgM)

produced at first response to antigen, can serve as B-cell receptor, fixes complement

immunoglobulin D (IgD)

receptor on B cells

immunoglobulin E (IgE)

antibody of allergy, worm infections

proliferate and differentiate B cells and T cells when challenged by antigen

What is the purpose of clonal expansion

clone

proliferation of a particular lymphocyte, genetically identical cells, some of which are memory cells

opsonize

to coat a pathogen, cell, or foreign particle with special immune proteins—called opsonins—so that immune cells can easily recognize, grab, and destroy it

granulocytes and agranulocytes

What are the two different types of white blood cells?

neutrophils, eosinophils, basophils, and mast cells

What are the four different types of granulocytes?

neutrophils

short-lived phagocytes in blood, active engulfers and killers of bacteria

eosinophils

attracted to sites of parasitic infection and antigen-antibody reactions

basophils

function in inflammatory events

mast cells

specialized tissue cells that trigger local inflammatory reactions like allergic symptoms

monocytes and lymphocytes

What are the two different types of agranulocytes?

monocytes

blood phagocytes that rpidly leave circulation and mature into macrophages and dendritic cells

lymphocytes

cells involved in specific immune response such as B cells (produce antibodies) and T cells (mediate cellular immunity)

natural killer cells

lymphocyte related to T cells, lack antigen specificity, circulate through spleen, blood, lungs

1st killer cells attack cancer cells and virus0infected cells in a similar manner to Tc cells

do not possess antigen receptors

cytotoxic T cells

lead to destruction of infected host cells and other foreign cells

serotyping

antigen-antibody technique for identifying, classifying, subgrouping bacteria into serotypes

employs antisera against cell antigens such as: capsule, flagellum, cell wall (LPS)

One Health

the health of all life on earth is connected, a concept that captures the interrelated nature of microbes, environment, and animals (including humans)

eutrophication

addition of excess nutrients to aquatic ecosystems

causes heavy surface growth of cyanobacteria and algae that shuts off oxygen supply to lake, triggered by industrial wastes, detergents in household wastewater, or runoff from manure and fertilizer-rich fields

true pathogen

capable of causing disease in healthy people with normal immune defenses

inflammation

complex response to injury to tissues that protects the host and aids in repair

subclinical

infection that produces no noticeable symptoms

fomite

inanimate object that harbors and transmits pathogens

opportunistic pathogen

causes disease when host defenses are compromised or when they become established in a part of the body that is not natural to them

vector

live animal that transmits an infectious agent from one host to another

mechanical vector

transports infectious agent without being infected

biological vector

actively participates in pathogens life cycle, serving as site where it multiplies or completes development

phagocytosis

cell engulfs and destroys foreign particles or pathogens

aerosol

suspension of fine dust or moisture particles in the air that contains live pathogens

epidemiology

study of disease or adverse occurences experienced by populations

incidence

number of new cases over certain time period

asymptomatic

infection with no noticeable symptoms, no signs of disease

mortality

number of deaths in a population due to a certain disease

morbidity

number of people afflicted with a certain disease

prevalence

total number of existing case with respect to entire population

secondary infection

infection that occurs during or after treatment of another infection

herd immunity

when a significant portion of a population becomes immune to a disease, limited its spread and indirectly protecting those not immune

communicable

infectious disease transmittable from one host to another

lysoszyme

enzyme in tears and saliva that hydrolyzes the peptidoglycan in bacterial cell walls

non-communicable

does not arise through transmission from host to host

antigen

substance that provokes immune response

antibody

immunoglobulin produced by B cells that binds to/counteracts a specific antigen

epitope

portion of antigen molecule recognized and bound by antibody

opsonization

antibodies coat microbes to make them more recognizable to phagocytes

nitrification

2 steps of oxidation: ammonium (NH4+) → nitrile (NO2-) → nitrate (NO3-)

nitrogen fixation

conversion of N2 gas into ammonium (NH4+) by rhizobia and other bacteria

rhizospheren

zone of soil surrounding roots of plants; contains associated bacteria, fungi, protozoa, a complex

symbiosis can result between plants and microbes in this area

denitrification

conversion of NO3- to N2 by species such as Bacillus and Pseudomonas