Microbiology Chapter 9 And 10 – Flashcards

 Definition: Reduction in the number of
microorganisms and viruses, particularly
potential pathogens, on living tissue

Ex: Iodine; alcohol

 Comments: Antiseptics are frequently disinfectants
whose strength has been reduced to make
them safe for living tissues.

 Definition :Refers to an environment or procedure
free of pathogenic contaminants

 Ex: Preparation of surgical field;
handwashing; flame sterilization
of laboratory equipment

Comments: Scientists, laboratory technicians, and
health care workers routinely follow
standardized aseptic techniques.

 Def: Suffixes indicating destruction of a type
of microbe

 Ex: Bactericide; fungicide;
germicide; virucide

 Comm: Germicides include ethylene oxide,
propylene oxide, and aldehydes.

 Def: Removal of microbes by mechanical
means

Ex: Handwashing; alcohol swabbing
at site of injection

Comm: Chemicals play a secondary role to the
mechanical removal of microbes.

 Def: Destruction of most microorganisms and
viruses on nonliving tissue

Ex: Phenolics; alcohols; aldehydes;
soaps

Comm: The term is used primarily in relation to
pathogens.

Def: Use of heat to destroy pathogens
and reduce the number of spoilage
microorganisms in foods and beverages

Ex: Pasteurized milk and fruit juices

Comm: Heat treatment is brief to minimize alteration
of taste and nutrients; microbes still remain
and eventually cause spoilage

Def: Removal of pathogens from objects to
meet public health standards

Ex: Washing tableware in scalding
water in restaurants

Comm: Standards of sanitization vary among
governmental jurisdictions.

Def: Suffixes indicating inhibition, but not
complete destruction, of a type of
microbe

Ex: Bacteriostatic; fungistatic;
virustatic

Comm: Germistatic agents include some chemicals,
refrigeration, and freezing.

 Def: Destruction of all microorganisms and
viruses in or on an object

Ex: Preparation of microbiological
culture media and canned food

Comm: Typically achieved by steam under pressure,
incineration, or ethylene oxide gas.

Antibacterial Drugs That Inhibit Cell Wall Synthesis

Spectrum of action: Gram-positive
(G+) bacteria

Route of administration: Topical

Adverse effects: Toxic to kidneys

Antibacterial Drugs That Inhibit Cell Wall Synthesis

Representative natural penicillins: Penicillin G, Penicillin V
Representative semisynthetic penicillin: Ampicillin

Representative semisynthetic cephalosporins: Cefixime, Ceftriaxone
Cefuroxime

Penicillium (penicillins) and
Cephalosporium (cephalosporins); bind
to and deactivate the enzyme that
cross-links the NAM subunits of
peptidoglycan

Antibacterial Drugs That Inhibit Cell Wall Synthesis

Blocks the gene for an enzyme that
forms mycolic acid; analog of the
vitamins nicotinamide and pyridoxine

Spectrum of action: Mycobacteria,
including M. tuberculosis and M. leprae

Route of administration: Oral

Adverse effects: May be toxic to liver

Antibacterial Drugs That Inhibit Cell Wall Synthesis

Directly interferes with the formation
of alanine-alanine bridges between
NAM subunits

Spectrum of action: Effective against
most G+ bacteria but generally reserved
for use against strains resistant to other
drugs such as methicillin-resistant
Staphylococcus aureus (MRSA)

Route of administration: IV

Adverse effects: Damage to ears and
kidneys, allergic reactions

Antibacterial Drugs That Inhibit Protein Synthesis

Gentamicin,Streptomycin, Tobramycin

Inhibit protein synthesis
by irreversibly binding to the 30S subunit
of prokaryotic ribosomes, this either
causing the ribosome to mistranslate
mRNA

Spectrum of action: Broad: effective
against most G- bacteria

Route of administration: IV; do not
traverse blood-brain barrier

Adverse effects: Toxic to kidneys and
to auditory nerves, causing deafness

Antibacterial Drugs That Inhibit Protein Synthesis

Spectrum of action: Broad, but rarely
used except in treatment of typhoid
fever

Route of administration: Oral;
traverses blood-brain barrier

Adverse effects: In 1 of 24,000
patients, causes aplastic anemia, a
potentially fatal condition in which
blood cells fail to form;

Antibacterial Drugs That Inhibit Protein Synthesis

Azithromycin, Erythromycin

Spectrum of action: Effective against
G+ and a few G- bacteria

Route of administration: Oral; do not
traverse blood-brain barrier

Adverse effects: Nausea, mild gastrointestinal
pain, vomiting; erythromycin
increases risk of cardiac arrest

Antibacterial Drugs That Inhibit Protein Synthesis

Doxycycline, Tetracycline

Carry amino acids,
from binding to ribosomes at the 30S
subunit’s docking site

Spectrum of action: Most are broad:
effective against many G+ and Gbacteria
as well as against bacteria
that lack cell walls, such as
Mycoplasma

Adverse effects: Nausea, diarrhea,
sensitivity to light; forms complexes
with calcium, which stains developing
teeth and adversely affects the
strength and shape of bones

Antibacterial Drugs That Alter Cytoplasmic Membranes

Spectrum of action: Effective
against G+ bacteria, particularly
Pseudomonas, and some amoebae

Route of administration: Topical

Adverse effects: Toxic to kidneys

Antibacterial Drugs That Are Antimetabolites

Sulfadiazine, Sulfadoxine, Sulfanilamide

Synthetic drugs; first produced as a dye;
analogs of PABA

Spectrum of action: Broad: effective
against G+ and G- bacteria and
some protozoa and fungi; however,
resistance is widespread

Adverse effects: Rare: allergic
reactions, anemia, jaundice, mental
retardation of fetus if administered in
last trimester of pregnancy

Antibacterial Drugs That Are Antimetabolites

Blocks second metabolic step in the
formation of folic acid from PABA;
synergistic with sulfonamides

Spectrum of action: Broad: effective
against G+ and G- bacteria and some
protozoa and fungi; however,
resistance is widespread

Adverse effects: Allergic reactions or
liver damage in some patients

Antibacterial Drugs That Inhibit Nucleic Acid Synthesis

Representatives: Ciprofloxacin, Moxifloxacin, Ofloxacin

Synthetic agents that inhibit DNA
gyrase, which is needed to correctly
replicate bacterial DNA; penetrate
cytoplasm of cells

Spectrum of action: Broad: G+ and
G- bacteria are affected

Adverse effects: Tendonitis, tendon
rupture

Antibacterial Drugs That Inhibit Nucleic Acid Synthesis

Representative: Metronidazole flagl

Spectrum of action: Obligate
anaerobic bacteria

Adverse effect: hairy black tongue

Antibacterial Drugs That Inhibit Nucleic Acid Synthesis

Representatives: Rifampin

Bind to bacterial RNA polymerase,
preventing transcription of RNA

Spectrum of action: Bacteriostatic
against aerobic G+ bacteria;
bactericidal against mycobacteria

Antiviral Drugs That Inhibit Viral Uncoating

Neutralizes acid environment within
phagolysosomes that is necessary for
viral uncoating

Spectrum of action: Influenza A virus

Adverse effects: Toxuc to central
nervous system; results in nervousness,
irritability, insomnia, and blurred vision

Antiviral Drugs That Inhibit Nucleic Acid Synthesis

Inhibits DNA and RNA synthesis

Spectrum of action: Viruses that code
for kinase enzymes: herpes, Epstein-
Barr, cytomegalovirus, varicella viruses, chickenpox

Antiviral Drugs That Inhibit Nucleic Acid Synthesis

Representatives: Azidothymidine (AZT

Inhibits DNA synthesis; viral reverse transcriptase
more likely to incorporate these drugs;
used in conjunction with protease
inhibitor to treat HIV

Spectrum of action: HIV, hepatitis B
virus

Adverse effects: Nausea, bone
marrow toxicity

Antiviral Drugs That Inhibit Nucleic Acid Synthesis

Inhibits DNA and RNA synthesis; viral DNA polymerase
more likely to incorporate the drugs

Spectrum of action: Respiratory
syncytial, hepatitis C, influenza A,
measles, some hemorrhagic fever
viruses

Adverse effects: Perhaps harmful to
developing fetus

Antiviral Drugs That Inhibit Viral Proteins

Which is unique to HIV, allowed
the creation of drugs that block the active
site

Spectrum of action: HIV

Antifungal Drugs That Inhibit Cell Membranes

Representatives: Fluconazole, Itraconazole, Ketoconazole, Voriconazole

Antifungal action due to inhibition of
synthesis of ergosterol

Spectrum of action: Fungi and
protozoa

Antifungal Drugs That Inhibit Cell Membranes

Representatives: Amphotericin B, Nystatin

Associate with molecules of ergosterol,
forming a pore through the fungal
membrane

Spectrum of action: Fungi, some
amoebae

Route of administration:
Amphotericin B: IV; nystatin: topical

Adverse effects: Chills, vomiting, fever

Anthelmintic Drugs That Are Antimetabolites

Changes membrane permeability to
calcium ions, which are required for
muscular contraction

Spectrum of action: Cestodes,
trematodes, tapeworm

Antiprotozoan Drugs That Are Antimetabolites

Spectrum of action: Protozoa,
Pneumocystis

Adverse effects: Possible rash,
diarrhea, headache

Antiprotozoan Drugs That Inhibit DNA Synthesis

Representatives:Natural quinine, Semisynthetic quinines: Chloroquine Mefloquine, Primaquine

Derived from the bark of cinchona
tree; inhibit metabolism of malaria
parasites

Spectrum of action: Plasmodium

Adverse effects: Allergic reactions,
visual disturbances