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Microbiology Lecture 2 Exam Study Guide
Chap
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Humoral immunity- immunity involving B cells and an antibody response; works to
eliminate extracellular antigens

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B cells- type of lymphocyte programmed to make antibodies; responsible humoral
immunity; develop in bone marrow

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Cytotoxic T cells- type of lymphocyte programmed to destroy infected or cancerous
“self” cells

•

Helper T cells- type of lymphocyte programmed to activate B cells and
macrophages, and assist other parts of the adaptive immune response

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Immunoglobulin Classes
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IgM- direct protection by neutralizing viruses and toxins, immobilizing motile
organisms, preventing microbes from adhering to cell surfaces, and crosslinking antigens; produced in response to T-independent antigens; primary
response

•

IgG- transported across placenta; provides protection through 1st several
months after birth; direct protection by neutralizing viruses and toxins,
immobilizing motile organisms, preventing microbes from adhering to cell
surfaces, and cross-linking antigens

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IgA- secreted into mucus, tears, and saliva, providing mucosal immunity; in
breast milk, protecting intestinal tract of infants; protects mucous membranes
by neutralizing viruses and toxins, immobilizing motile organisms, preventing
microbes from adhering to cell surfaces

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IgD- development and maturation of the antibody response

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IgE- allows cells to detect parasites and other antigens and respond by
releasing their granule contents; involved in allergic reactions

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The nonspecific defenses impart a general type of protection against all kinds of
foreign invaders, while the specific defenses create protection that is tailored to
match the particular antigen that has invaded the body
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16
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Relatively few microorganisms are pathogens that cause damage

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Normal microbial- organisms that routinely reside on body’s surfaces

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Mutualism- both partners benefit

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Commensalism- one partner benefits, other is unharmed

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Parasitism- one organism benefits at the expense of other

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Resident microbial- inhabit sites for extended periods

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Transient microbiota- inhabit temporarily

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Colonization- refers to microbe establishing itself on body surface
o Infection could be used to refer to pathogen


Primary infection- initial infection



Secondary infection- damage can predispose individual; respiratory
illness



Primary pathogen- microbe or virus that causes disease in otherwise healthy
individual



Opportunistic pathogen- causes disease only when body’s innate or adaptive
defenses are compromised or when introduced into unusual location
o Virulence- degree of pathogenicity



Incubation period- time between infection and onset



Illness- signs and symptoms of disease



Convalescence- recuperation, recovery from disease



Carriers- may harbor and spread infectious agent for long periods of time in
absence of signs of symptoms

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Acute infections- symptoms develop quickly, last a short time



Chronic infections- develop slowly, last for months or years



Latent infections- never completely eliminated; microbe exists in host tissues without
causing symptoms



Localized infection- microbe limited to small area



Systemic infection- agent disseminated throughout body



Adhesins- attach to host cell receptor



Skin is difficult barrier to penetrate



Exotoxins- proteins with damaging effects
o Found on gram – and gram + cells



Endotoxins
o Only found on gram – cells

Chap
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18


Passive immunity- results when antibodies are transferred to an individual



Active immunity- results from an immune response in an individual upon exposure to
an antigen



Herd immunity- phenomenon that occurs when a critical concentration of immune
hosts prevent the spread of an infectious agent



Inactivated vaccines- composed of killed bacterial cells , inactivated virus, or
fractions of the pathogen; unable to replicate, but retains the immunogenicity of the
pathogen or toxin; cannot cause infections or revert to pathogenic forms



Attenuated vaccine- composed of weakened form of the pathogen that is generally
unable to cause disease; replicates in the vaccine recipient, causing infection with
undetectable or mild disease that typically results in long-lasting immunity

Chap
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20


Broad-spectrum antimicrobial- effective against a wide range of microorganisms,
often including both gram + and gram – bacteria; used for treating acute lifethreatening diseases when immediate antimicrobial therapy is essential



Narrow-spectrum antimicrobial- effective against a limited range of
microorganisms; use requires that the pathogen be identified and its antimicrobial
susceptibility tested

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Minimum inhibitory concentration (MIC)- lowest concentration of a specific
antimicrobial drug needed to prevent the growth of a given bacterial strain in vitro



Minimum bactericidal concentration (MBC) lowest concentration of a specific
antimicrobial drug that kills 99
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Because of this, drugs
that interfere with the uncoating step prevent viral replication
o Nucleic acid synthesis- take advantage of the error-prone, virally encoded
enzymes that replicate viral nucleic acid
o Genome integration- prevent virus from inserting the DNA copy of its
genome into that of the host cell
o Assembly and release of viral particles- virally encoded enzymes required
for the assembly and release of viral particles are the targets of medications
used to treat certain viral infections



Mechanisms of action of antifungal drugs
o Plasma membrane- target of most antifungal drugs found in plasma
membrane but not human cells


Polyenes- disrupts fungal membrane, killing the cells by allowing its
cytoplasmic contents to leak out

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Azoles- defective fungal membranes that leak cytoplasmic contents



Allylamines- inhibit enzyme in pathway

o Cell wall synthesis- causes fungal cells to burst
o Cell division- interferes with nuclear division
o Nucleic acid synthesis- common feature and is a poor target for antifungal
drugs



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