Microbiology and Parasitology Lecture (L7-9) Flashcards
(79 cards)
1
Q
is the study of the vital life
processes of organisms
A
Physiology
2
Q
concerns the vital life
processes of microorganisms.
A
Microbial physiology
3
Q
- ideally suited- inexpensive to maintain, take up little space and
reproduce quickly (E. coli)
A
Bacteria
4
Q
All living protoplasm contains six major
chemical elements:
A
carbon, hydrogen,
oxygen, nitrogen, phosphorus, and sulfur.
5
Q
Other elements, usually required in lesser
amounts, include :
A
sodium, potassium,
chlorine, magnesium, calcium, iron, iodine,
and some trace elements.
6
Q
All microbes have a need for three things:
A
carbon, energy, and electrons
(other nutrients).
7
Q
refers to all the
biochemical reactions that
occur in a cell or organism.
A
Metabolism
8
Q
a protein that either causes a particular chemical reaction to occur or
accelerates it.
A
Biologic catalyst
9
Q
- Remain within the cell that
produced them - Digestive enzymes of
Phagocytes
A
Endoenzymes
10
Q
- Leave the cell to catalyze rxns
outside the cell - Cellulase and pectinase, which
are secreted by saprophytic
fungi to digest cellulose and pectin.
A
Exoenzymes
11
Q
-cannot, on their
own, catalyze a chemical reaction.
- must link up with a cofactor to catalyze a chemical reaction.
A
Apoenzymes
12
Q
reactions that “break down”
molecules requiring the breaking of bonds. Major E source
A
Catabolic
13
Q
reactions that build new
molecules requiring the formation of
bonds.
A
Anabolic
14
Q
is a series of linked
biochemical reactions that occur in a stepwise
manner, leading from a starting material to an
end product
A
biochemical pathway
15
Q
produced during glycolysis are converted into acetyl-CoA molecules which
then enter The CAC.
A
Pyruvic acid
16
Q
the study of
heredity
A
Genetics
17
Q
-the study of the mechanisms of heritable information in bacteria, their chromosomes, plasmids, transposons and
phages.
-The entire genetic content of a cell is its genome.
A
Bacterial Genetics
18
Q
- Complete collection of genes
- The genetic material passed between generations.
A
Genotype
19
Q
- All its physical traits, attributes
or characteristics - Manifestation of genotype
A
Phenotype
20
Q
- Actively expressed all the time
- ribosomes are constantly
needed for protein synthesis
A
Constitutive Genes
21
Q
- Expressed only when needed
- the glucose transporter proteins that muscle cells produce in response to insulin
A
Inducible Genes
22
Q
beneficial, harmful, silent
A change in the characteristics of a cell caused by a change in the DNA molecule that is transmissible to the
offspring
A
Mutations
23
Q
- Are of benefit to the organism
- lead to new versions of proteins that help
organisms adapt to changes in their environment. - lead to antibiotic-resistant strains of bacteria.
A
Beneficial mutation
24
Q
-leads to the production of a nonfunctional enzyme.
-Lethal mutation
A
Harmful mutation
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* They have no effect on the cell
Silent Mutations
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* Involves bacteriophages and
the acquisition of new viral genes
* Lysogenic conversion –>
lysogeny
* prophage
* The bacterial cell containing
the prophage: lysogenic cell
* imparts genes with special functions to bacterial cells
without such functions.
* Corynebacterium diphtheriae
Lysogenic Conversion
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* transfer of a DNA fragment from one
bacterium to another by a bacteriophage.
Transduction
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is a form of genetic recombination in which a DNA fragment from a dead, degraded bacterium enters a competent recipient bacterium and is
exchanged for a piece of DNA of the recipient.
Transformation
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* Cell-to-cell contact
* Sex pilus
* encoded by plasmids or transposons.
* a. General mechanism of transfer of conjugative
plasmids by conjugation in Gram-negative bacteria
* This is the mechanism by which resistance
plasmids (R-plasmids), coding for multiple
antibiotic resistance and conjugation pilus
formation, are transferred from a donor
bacterium to a recipient.
* F+ conjugation
* the donor bacterium carries a DNA sequence
called the fertility factor, or F-factor.
* c. Hfr (high frequency recombinant) conjugation.
Conjugation
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grow only in the presence of oxygen.
Obligate aerobes
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require a low concentration of oxygen (2% to 10%) for growth, but higher
concentrations are inhibitory.
Microaerophiles
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grow only in the absence
of oxygen and, in fact, are often inhibited or killed
by its presence.
Obligate anaerobes
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grow only in the absence
of oxygen and, in fact, are often inhibited or killed
by its presence.
Obligate anaerobes
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cannot use oxygen to
transform energy but can grow in its presence.
Aerotolerant anaerobes
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grow with or without
oxygen, but generally better with oxygen.
Facultative anaerobes
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best at a pH 7.0–7.4
Neutrophiles grow
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prefer pH of 2 to 5
Acidophiles
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grow
best at a pH above 8.5.
Alkaliphiles
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* the diffusion of water across a membrane from an area of higher water concentration (lower solute concentration) to lower water concentration (higher solute concentration).
* Solution: consists of a solute dissolved in a solvent
* Solute refers to all the molecules or ions dissolved in the water (the solvent).
Osmosis
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* the diffusion of water across a membrane from an area of higher water concentration (lower solute concentration) to lower water concentration (higher solute concentration).
* Solution: consists of a solute dissolved in a solvent
* Solute refers to all the molecules or ions dissolved in the water (the solvent).
41
use radiant energy (light)
as their primary energy source.
Phototrophs
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use the oxidation and
reduction of chemical compounds as their primary energy source.
Chemotrophs
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require only carbon dioxide as a
carbon source.can synthesize
organic molecules from inorganic nutrients.
Autotrophs
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require organic forms of carbon. A
heterotroph cannot synthesize organic molecules from inorganic nutrients.
Heterotrophs
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thrive deep in the ocean and in oil wells, where the atmospheric pressure is very high.
Piezophiles
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involves the destruction or elimination of all
microbes, including cells, spores, and viruses.
Sterilization
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Elimination of most or all pathogens (except bacterial spores)
Disinfection
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An agent that is cidal in action will kill
* General terms like germicidal agents (germicides), biocidal agents (biocides), and microbicidal agents (microbicides) are disinfectants or antiseptics that kill microbes.
Cidal
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kill bacteria, but not necessarily bacterial endospores. Sporicidal agents are required to kill spores
Bacterial agents
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kill fungi, including fungal spores.
Fungicidal agents
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kill algae in swimming pools and hot tubs.
Algicidal agents
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agents destroy viruses.
Viricidal
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agents kill Pseudomonas species, and tuberculocidal agents kill M. tuberculosis
Pseudomonicidal
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agent is a drug or chemical that
inhibits reproduction of microorganism
* s, but does not necessarily kill them.
microbistatic
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agent is one that specifically
inhibits the metabolism and reproduction of bacteria.
* Freeze-drying (lyophilization) and rapid freezing
(using liquid nitrogen) are microbistatic techniques that are used to preserve microbes for future use or study.
* Sepsis refers to the presence of pathogens in blood or tissues, whereas asepsis means the absence of pathogens.
bacteriostatic
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used to eliminate and exclude pathogens.
Aseptic techniques
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the prevention of infection.
Antisepsis
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use of any chemical ( drug) to treat any disease or condition.
Chemotherapy
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chemotherapeutic agents used to treat infectious diseases
Antimicrobial agents
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Effective in treating malaria
Cinchona Bark
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a substance produced by a microorganism that is effective in killing or inhibiting the growth of other microorganisms.
Antibiotic
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* interferes with the synthesis and cross-linking of
peptidoglycan>> inhibiting cell wall synthesis
**β -lactam drugs
* kills bacteria through binding of the beta-lactam ring to DD
-transpeptidase, inhibiting its cross -linking activity and preventing new cell wall formation.
Penicillin
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* β-lactam drugs; produced by molds; interfere
with cell wall synthesis and are bactericidal
* They have no activity against LAME: Listeria,
Atypical (Mycoplasma/Chlamydia), MRSA,
Enterococci (except MRSA in Ceftobiprole and
other 5th Gen)
* 1st gen: against Gram-positive bacteria.
* 2nd gen: increased activity against Gram (-);
* 3rd gen: even greater activity against Gram (-)
(including Pseudomonas aeruginosa).
* 4th gen: Gram (-) and (+), including P.
aeruginosa)
Cephalsporin
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* Broad-spectrum; bacteriostatic
* inhibit the 30Sribosomal subunit, hindering the binding
of the aminoacyl-tRNA to the acceptor site on
the mRNA-ribosome complex.
Tetracyclines
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-Broad spectrum: bactericidal drugs that inhibit protein synthesis
- effective against a wide variety of aerobic gram,-negative bacteria, but are ineffective against anaerobes
Aminoglycosides
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* Bacteriostatic at
lower doses but bactericidal at higher doses
* Inhibit protein synthesis
* erythromycin, clarithromycin, and Azithromycin.
Macrolides
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* bactericidal drugs thatinhibit DNA synthesis
* ciprofloxacin, is effective against members of the family Enterobacteriaceae and P. aeruginosa.
Fluoroquinolones.
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-a single antimicrobial agent is not sufficient to destroy all the pathogens
-two or more drugs may be used
simultaneously to kill all the
pathogens
Multi-drug therapy
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* When the use of two drugs produces an extent of pathogen killing that is less than that achieved by either drug alone, the phenomenon is known as
antagonism
Synergism
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* When the use of two antimicrobial agents to treat an
infectious disease produces a degree of pathogen killing that is far greater than that achieved by
either drug alone, the phenomenon is known as
Synergism.
Antagonism
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-By binding with cell membrane sterols (e.g., nystatin and amphotericin B)
-By interfering with sterol synthesis (e.g., clotrimazole and miconazole)
-By blocking mitosis or nucleic acid synthesis (e.g., griseofulvin and 5- Flucytosine
Antifungal Agents
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* usually quite toxic to the host
* (a) interfering with DNA and RNA
synthesis (e.g., chloroquine, pentamidine, and quinacrine), or
* (b) interfering with protozoal
metabolism (e.g., metronidazole; brand name Flagyl).
ANTIPROTOZOAL AGENTS
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* are particularly difficult to develop and use because viruses are produced within host cells.
* Work by inhibiting viral replication within cells.
* The first antiviral agent effective against human immunodeficiency virus (HIV) —zidovudine (also known as azidothymidine [AZT])—was introduced in 1987.
ANTIVIRAL AGENTS
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Superbugs strains of bacteria, viruses, parasites and fungi that are resistant to most of the antibiotics and other medications commonly used to treat the infections they cause.
DRUG RESISTANCE
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* resistant to all anti- staphylococcal drugsexcept vancomycin and one or two more recently developed drugs (e.g., Synercid and Zyvox).
MRSA and MRSE
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* These strains are resistant to
most anti-enterococcal drugs, including vancomycin.
* Enterococcus spp. are common causes of healthcare-associated infections, especially urinary tract infection
* May be intrinsic or acquired resistance.
Vancomycin-resistant
Enterococcus spp.
(VRE)
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* These strains are resistant to the two most effective first- line therapeutic drugs— isoniazid and rifampin
* Extensively drug-resistant strains, called XDR-TB are
also resistant to the most effective second-line therapeutic drugs— fluoroquinolones and at
least one of the following: amikacin, kanamycin,
capreomycin.
Multidrug-resistant M. tuberculosis
(MDR-TB)
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* The patient may become allergic to the agent. For example, penicillin G in low doses often sensitizes those who are prone to allergies; when these
persons receive a second dose of penicillin at some later date, they may have a severe reaction known as
anaphylactic shock, or they may break out in hives.
Allergy
79
* Prolonged antibiotic use can lead to
population explosions of microorganisms
that are resistant to the antibiotic(s) being
used. Such overgrowths are known as
“superinfections.”
* A superinfection can be thought of as a
“population explosion” of organisms that
are usually present only in small numbers.
* Yeast vaginitis
Superinfections
