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MicroBio exam 2

Substances produced by various species of microorganisms that inhibit or destroy other microorganisms. Antibiotics
Destroy or inhibit microbial cells without simultaneously damaging host tissues. Selective Toxicity
Agents are effective against a limited array of different microbial types Narrow Spectrum
Example of a Narrow Spectrum drug bacitracin
Agents are active against a wide range of different microorganisms. Broad Spectrum
Example of a broad spectrum drug tetracycline
The smallest concentration of drug that prevents visible growth after 18 to 24 hour incubation. Minimum Inhibitory Concentration (MIC)
The lowest concentration of drug that result in a 99.9% decline in bacterial numbers. Minimum Bactericidal Concentration (MBC)
The ratio of a drug’s toxic dose to its MIC. The smaller of the ratio, the greater of the potential for toxic drug reaction Therapeutic Index
The combined activity is greater than the sum of the independent activities. Synergy is frequently defined as a fourfold greater reduction in the MIC or MBC of both agents. Synergy
The combined activity equals the sum of the separate activities. Indifference
The activity of the combination is four fold less than the sum of the activities of the independent agents Antagonism
Side Effects of Drugs 1. Toxicity to Organs 2. Allergic Reactions 3. disruption of normal resident flora
Antimicrobic agents disrupt beneficial resident flora and lead to the overgrowth of opportunistic pathogens. Superinfection
Drug inactivation Mechanisms 1. Drug is inactivated. 2. Drug fails to reach its target. 3. Target is altered. 4. An alternative pathway is developed.
How is resistance acquired? 1. through chromosomal mutation 2. resistant factors (R factors)
pumps (encoded by plasmids or chromosomes) can actively transport drugs and other chemicals out of cells. These pumps lack of selectivity, one type of pump can expel a broad spectrum of drugs, detergent, and other toxic substances Multidrug Resistant (MDR)
Inhibitors of peptidoglycan precursor synthesis cycloserine, vancomycin, bacitracin
Inhibitors of transpeptidation penicillins, cephalosporins
Protein synthesis inhibitors Streptomycin and other aminoglycosides, choloramphenicol, erythromycin and other macrolides, tetracyclines
Agents affecting nucleic acid metabolism: Antimetabolites: Sulfonamides and trimethoprim DNA gyrase inhibitor: Quinolones RNA polymerase inhibitor: Rifampin
Agents that act on cell membranes: Polymyxins Antifungal agents (polyene)
MOA of beta lactams Penicillin produces a stable, covalent complex with the transpeptidase and the enzyme becomes permanently inactivated.
natural penicillins penicillin G
penicillinase resistant penicillins Methicillin, Oxacillin, Nafcillin, Cloxacillin
Aminopenicillins Ampicillin, amoxicillin
Carboxypenicillins Carbenicillin, Ticarcillin
Ureidopenicillins Piperacillin
1st generation cephalosporins gram positive and modest gram negative activity.
2nd generation cephalosporins better activity against gram negative bacteria, and some of them have anti-anaerobe activity. Generally less active against gram positive bacteria than the first-generation cephalosporins.
3rd generation cephalosporins less activity against gram positive bacteria than the first generation cephalosporins, but have broad-spectrum activity against most gram negative bacteria.
4th generation cephalosporins spectrum similar to the third generation, but have an increased stability to hydrolysis by ß-lactamases.
ß-Lactamase Inhibitors They do not have high intrinsic antibacterial activity but they inhibit most plasmid-mediated penicillinases found in gram negative bacteria. ex: clauvulanic acid
monobactams They are relatively resistant to ß-lactamase. They have a gram negative spectrum. They have no activity against gram positive bacteria or anaerobes.
Carbapenems broadest antimicrobial spectrum of any antibiotics. Stable to almost all ß-lactamases (ex: imipenem)
it is more difficult to achieve selective toxicity for ___ infection than for ___ infection fungi infection than for bacteria infection
antiobiotic susceptibility determination by disk diffusion kirby bauer technique
the radius of the area in which growth has been rpevented zone of inhibition
larger zone of inhibition =? more potent antibiotic
drug A has a toxic dose = 10, MIC = 9 drug B has a toxic dose = 10, MIC = 1 which drug is more likely to cause toxic drug reactions? drug A because smaller toxic dose/MIC ratio which means smaller Therapeutic index
characteristics of the ideal antimicrobial drug selectively toxic, microbicial rather than microbistatic, soluble, potent, not broken down prematurely, not subject to antimicrobial resistance, readily delivered to the site of infection, not costly, doesnt disrupt the hosts health
what is preferred? narrow or broad spectrum drugs? narrow spectrum
T/F the building block for peptidoglycan is the NAG-NAM disaccharide unit. NAM is linked to a pentapeptide TRUE
t/F Both bacitracin and cycloserine inhibit bacteria cell wall synthesis TRUE
T/F Pencillin reversible inhibits the transpeptidase FALSE penicillin is irreversible
is there a high or low degree of cross sensitivity beterrn cephalosporins and penicillins high
T/F penicillin inhibits the biosynthesis of the NAG-NAM disaccharide unit. NAM is linked to a pentapeptide FLASE, it inhibits transpeptidaation, cyclosporine inhibits the biosynthesis
which of the following inhibit gram negative bacteria? a. penicillin G b. methicillin c. ampicillin c. ampicillin
T/F Vancomycin is a beta lactam antibiotic that inhibits cell wall synthesis FALSE, it is a glycopeptide, not a beta lactam
T/F Vancomycin binds to the D-Ala-D-Ala terminus of pentapeptide that is linked to NAM. this sterically interferes with elongation of the peptidoglycan TRUE
p site stands for peptidyl site
a site stands for acceptor site
formation of a peptide bond is also known as transpeptidation reaction
translocation occurs from ___ site to ___ site from A site to P site (in left direction)
bacterial ribosome components 30s + 50s = 70s (versus 40s + 60s = 80s in eukaryotes)
aminoglycoside example streptomycin
aminoglycoside structure 2 or more amino sugars and an aminocyclitol (6 carbon) ring
residual bactericidal concetration persisting after the serum concentration has fallen bellow the MIC postantibiotic effect (PAE)
T/F streptomycin binds to the 30s ribosome. it inhibits the initiation of protein synthesis, causes the incorporation of incorrect amino acids and causes premature termination of protein synthesis TRUE
T/F streptomycin is bacteriocidal TRUE
T/F both chloramphenicol and erythromycin bind to the 50S ribosome TRUE
T/F same as penicillins, enzymatic inactivation of tetracycline is the most important mechanism for the occurance of tetracycline resistance FALSE, the most common is pumping out tetracycline from the cell
T/F sulfonamide inhibits PABA to dihydrofolic acid in bacteria and humans FALSE, it only inhibits it in microbes
T/F fluoroquinolones does not have good selective toxicity because it also inhibits human topoisomerase FALSE
T/F rifampin is widely used in treating a number of gram positive and gram negative infections because it has very good selective toxicity FALSE, used to treat mycobacterial infections
fungi includes: molds, yeasts, mushrooms, toadstools, puffballs
most common plant pathogen fungi
branched filaments in fungi hyphae or mycelium
divided into individual cells by septa true hyphae
have incomplete septa allowing exchange of nuclei and cytoplasm along the hyphae pseudohyphae
dimorphic growth of fungi: ___ state when in natural habitat and ___ state when in animals or humans hyphae in natural environment, yeast when in humans or animals
fungi that naturally inhabit the human body dermaphytes and candida
immunity to fungal infections consists of: - nonspecific barriers - inflammation - cell mediated defenses
cutaneous mycoses are infections that are strictly confined to: keratinized epidermis (skin, hair, nails)
cutaneous mycoses are called dermatophytoses (ringworm and tinea)
cutaneous mycosis infections are facilitated by: moist adn chafed skin
what is used to treat dermatophytoses? griseofulvin, azoles (imidazoles and triazoles) and allylamines
T/F griseofulvin binds to microtubule, therefore inhibiting fungal cell division TRUE
T/F imidazole inhibits ergosterol biosynthesis TRUE
widespread, dimorphic yeast Candida
____ is present in the normal flora of the oral cavity, gentialia, large intestine or skin of 20% of humans candida
accounts for 80% of nosocomial infections candida
causes cutaneous and subcutaneous infection in chronically moist areas of the skin and burn patients Candida
agents to treat candida: Nystatin (aka mycostatin)
T/F candida albicans is an important source for nosocomial infections TRUE
examples of subcutaneous fungal infections oral candidiasis (thrush), vaginitis (vaginal yeast infection)
treatment of vaginitis orally absorbed and vaginal tablets of triazoles and imidazoles, creams, lotions and powders
systemic mycoses (endemic mycoses) - histoplasma capsulatum - coccidiodes immitis - blastomyces dermatitidis
treatment for histoplasmosis amphotericin B
another name for histoplasmosis darlings disease when systemic
treatment for coccidiodomycosis amphotericin B
another name for coccidioidomycosis valley fever, san joquoin valley fever, californian valley fever, desert fever
treatment for blastomycosis amphotericin B
another name for blastomycosis gilchrist's diseases or chicago disease
systemic mycoses that is NOT endemic cryptococcosis
common infection of AIDS, cancer and diabetic patients cryptococcosis
treatment for cryptococcosis amphotericin B
systemic mycoses caused by opportunistic pathogen aspergillus
treatment of aspergillosis amphotericin B or azoles or Echinocandins (like caspofungin) if resistant
T/F cryptococcosis is an endemic and systemic disease FALSE
superficial mycoses causes: discoloration or disfiguration of the skin
___ causes mild scaling, mottling of skin tinae versicolor
____ causes whitish or colored masses on the long hairs of the body white piedra
____ causes darl, hard concretions on scalp hairs black piedra
T/F although amphotericin B is fungistatic, it is very important in treating fungal infections FALSE, it is fungicidal
must be provided to an organism essential nutrients
can be synthesized by an organism nonessential nutrients
required in relatively large quantities and play principal roles in cell structure and metabolism, such as proteins, carbohydrates macronutrients
required in small amounts and are involved in enzyme function and maintenance of protein structure, such as Mg2+, Zn2+. micronutrients
do not contain C and H at the same time, such as CO2 and H2O. Inorganic nutrients
contains C and H atoms, such as glucose organic nutrients
use inorganic carbon source (CO2). autotrophs
use organic carbon source. heterotrophs
use sunlight to photosynthesize phototrophs
oxidize chemical compounds chemotrophs
T/F chemoheterotrophs microbes use CO2 as carbon source FALSE
follows physical laws and generally does not require energy. Passive transport (diffusion, osmosis)
requires energy ATP active transport
Atoms or molecules move in a gradient from an area of higher density or concentration to an area of lesser density or concentration diffusion
Diffusion of water through a selectively permeable membrane osmosis
Two solutions having the same osmotic pressure such that, when separated by a semipermeable membrane, there is no net movement of solvent in either direction. isotonic
Having a lower osmotic pressure than a reference solution. hypotonic
Having a greater osmotic pressure than a reference solution (Hypertonic solutions are lethal to many microbes. Salt water and concentrated sugar solutions are examples of such solutions hypertonic
when water diffuses out of a cell with a cell wall and the cell shrinks away from the cell wall plasmolysis
can grow at 00C and have an optimum temperature below 150C. psychrophiles
can grow between 100C to 500C, but their optimal temperatures usually is between 200C to 400C. Most human pathogens have optimal temperatures between 30- 400C. mesophiles
usually require temperatures above 450C and grow optimally between 450C and 800C. thermophiles
taq DNA polymerase is an example of which temperature loving bacteria thermophiles
which temperature loving bacteria form endospores? thermophiles
A microorganism that lives and grows in the presence of free gaseous oxygen (O2). Aerobe
microorganism that cannot grow without O2. Many fungi and protozoas as well as many bacteria, have strict requirements for O2 in their metabolism obligate aerobe
A microorganism that grows best, or exclusively, in the absence of O2. anaerobe
This type of organism metabolizes by aerobic respiration when O2 is present, but in its absence, it adopts an anaerobic mode of metabolism. facultative anaerobe
The optimal pH range for most microorganisms is between pH 6 and pH 8
pH of normal human blood is pH = 7.4
microorganisms that live in habitats with a high solute concentration. halophiles
ormally do not reside in high-salt environment, but are highly resistant to high salt. facultative halophiles
T/F mesophiles can grow at 4 degrees C False
T/F obligate aerobes must grow in the presence of oxygen TRUE
The formation of two new cells of approximately equal size as the result of parent cell division binary fission
The time required for a complete fission cycle from parent cell to two new daughter cells. generation (doubling time)
average generation time for bacteria 30-60 minutes under optimal conditions
mathematics of population growth Nf=(Ni) X 2n
10 microbes, doubling time = 30 minutes at room temp. how many microbes will there be 2 hours later? 160
4 phases of the population growth curve lag phase, exponential growth (log) phase, stationary growth phase, and death phase
on the poulation growth curve, during which stage do microbes grow most rapidly? exponential growth phase
Kill microbes microbicidal agents
Prevent microbes from growing microbistatic agents
factors that influence the rate of microbes being killed by antimicrobial agents - length of texposure to the agent - effect of the microbial load (high vs. low load) - relative resistance of spores vs. vegetative forms - action of the agent: destructive or inhibitory
ways of altering protein function heat or heavy metal binding
gamma rays and x rays ionizing radiation
UV rays non-ionizing radition
ionizing radiation causes: DNA breakages
non-ionizing radiation causes: formation of thymine dimer
which type of radiation can penetrate a solid barrier ionizing radiation, NOT non-ionizing radiation
T/F both ionizing radiation and UV function by causing DNA breaks false, UV causes thymine formation
autonomous self-replicating DNA molecules that are extrachromosomal closed circular DNA plasmids
plasmids are found in which bacteria gram positive and gram negative
are plasmids required for bacterial survival NO
The replication of the plasmid is closely tied to chromosomal replication so that only a few plasmids are present in each cell. stringent plasmid
how big are stringent plasmids large plasmids
The replication of the plasmid is not tied to chromosomal replication so that many copies (even dozens) are present in a cell. relaxed plasmid
how big are relaxed plasmids? small plasmids
genes conferring resistance to antibiotics, and thus are important in medicine. R plasmids (R factors)
T/F plasmids are localized on a chromosome FALSE
T/F plasmids are absolutely essential for basic bacterial survival FALSE
a mode of sexual mating in which a plasmid (or other genetic material) is transferred from a donor cell to a recipient cell. conjugation
is cell contact required in conjugation? Yes cell contact is required
conjugation occurs primarily in which bacteria? gram negative bacteria
donor (or male) cell in conjugation F+ cells
recipient (of females)in conjugation F- cells
leads to transfer of plasmid DNA, but does not involve chromosomal DNA conjugation of an F+ cell and an F- cell
which cells (F+ or F-) have a pilus? F+ cells have a pilus
how do you form an Hfr strain (high frequency of recombination)? F factor integrates into a chromosome
What is transferred durign conjugation of an HFr+ cell with an F- cell Hfr transfers chromosomal DNA (rarely the entire genome is transferred)
what is an F' factor? An F factor originally integrated into the chromosome of a donor bacterium becomes free and carries away a segment of donor chromosome
what is another name for conjugation between an F' cell and an F- cell sexduction
promiscuous exchange of drug resistance occurs primarily by: conjugation and transduction
which bacteria are primarily involved in the promiscuous exchange of drug resistance? gram negative bacteria (except bacillus and staphpylococcus which are gram positive)
Bacteriaphage lyse cells lytic cycle
Bacteriaphage integrates into host cells and become lysogen lysogenic cycle
T/F for both conjugation and transduction, cell-cell contact is required FALSE
The process by which a bacteriophage (bacteria virus) serves as the carrier of DNA from a donor cell to a recipient cell is called transduction
Bacteria cell takes up small DNA molecules from environment. Does not need cell-cell contact as in conjugation transformation
T/F transformation is, in essence, bacteria cells take free DNA TRUE
transformation was discovered by Frederick Griffith
who discovered the transforming element? Oswald Avery
which bacteria are involved in tranformation? both Gram-positive streptococci and Gram-negative Haemophilus and Neisseria species.
Cells that are capable of accepting foreign DNA during transformation procedure are termed competent
what is another name for transposable elements? jumping genes
genetic units that are capable of mediating their own transfer from one chromosomal site to another chromosomal site, from a chromosomal location to a plasmid, or from a plasmid to a chromosome. transposable elements
overall effect of transposition: to scramble the genetic language
3 main types of transposable elements: A). Insertion sequence (IS) elements (B). Transposons (Tn) (C). Transposable prophages. Bacteriophage Mu is the typical example.
these transposable elements only encode 1 or 2 proteins required for transposition insertion sequence elements
these transposable elements do not carry drug resistance genes or other genes insertion sequence elements
T/F when insertion sequence elements jump from 1 location to another, it does not capture drug resistance TRUE
these transposable elements carry drug resistance and IS elements transposons
Bacteriophage Mu has the alternative of lytic growth or of lysogeny. transposable prophages (Mu)
T/F when the transposon jumps from 1 location to another location, it does not cause drug resistance FALSE
The transposable elements simply move from one location to another location without replicating. nonreplicative transposition
The DNA is duplicated, leaving a copy of itself in the original state while inserting itself into a new location via formation of a cointegrate. replicative transposition
A rapid assay to screen potential mutagenic and oncogenic compounds. Ames Test
T/F Ames test: A did not result in more colonies to grow in the absense of histadine, B resulted in more colonies growing. B is therefore mutagenic TRUE
Resident flora includes bacteria, fungi, and protozoa
which sites on the human body harbor resident flora? Human skin, gastrointestinal tract (oral cavity, pharynx, intestine), respiratory tract, and genitourinary tract
which sites in the human body remain free of resident flora? Organs and fluids inside the body cavity and the central nervous systems because host defense mechanisms maintain their sterility, also heart, liver lungs, kidneys, brain, bones, ovaries, sinuses, blood, urine, spinal fluid, semen, saliva, amniotic fluid
Which of the following anatomical sites does NOT harbor resident flora? A. lung b. skin c. respiratory tract d. GIT A. lung
why are microbes important in the body? - needed for normal intestinal development - significant source of vitamins - stimulate development of host defenses - essential in caries formation and gum disease - antagonistic against pathogens - facilitate completion of ameba life cycle in gut
Microorganisms that regularly cause infection and disease in healthy people with normal immune defenses. true pathogen (primary pathogen)
Microorganisms that rarely cause disease in healthy humans, but cause diseases when a host’s defense system is compromised opportunistic pathogen
a characteristic route that a microbe enters the tissues of the body. portal of entry
main portals of entry for microbes: usually the same anatomical regions that also support normal flora: skin, gastrointestinal tract, respiratory tract, and urogenital tract. Placenta is also a portal of entry for pathogens that infect during pregnancy and birth.
The minimum number of microbes that will cause infection. In general, microorganisms with smaller infectious dose have greater virulence. infectious dose (ID)
disease with a VERY small infectious dose (high virulence) tuberculosis
T/F resident flora stimulates the development of the immune system TRUE
how do pathogens attach? Through adhesion by mechanisms such as firmbriae, adhesive capsule, hooks and flagella, and envelope spikes
examples of virulence factors: (i). Extracellular enzymes (mucinase, keratinase, collagenase, and hyaluronidase) (ii). Bacterial toxin (iii). Antiphagocytic factors
toxic in minute amounts (endo or exotoxin)? exotoxin
toxic in high doses (endo or exotoxin)? endotoxin
specific to a cell type (endo or exotoxin)? exotoxin
systemic effect on body: fever and inflammation (endo or exotoxin)? endotoxin
composed of polypeptides (endo or exotoxin)? exotoxin
composed of lipopolysaccharide of cell wall (endo or exotoxin)? endotoxin
unstable with heat denaturation (endo or exotoxin)? exotoxin
stable with heat denaturation (endo or exotoxin)? endotoxin
converts to toxoid (endo or exotoxin)? exotoxin
does not convert to toxoid (endo or exotoxin)? endotoxin
stimulates antitoxins (endo or exotoxin)? exotoxin
does not stimulate antitoxins (endo or exotoxin)? endotoxin
stimulates fever (endo or exotoxin)? endotoxin
does not stimulate fever (endo or exotoxin)? exotoxin
secreted from live cell(endo or exotoxin)? exotoxin
released by cell during lysis (endo or exotoxin)? endotoxin
source: a few gram positive and gram negative (endo or exotoxin)? exotoxin
source: ALL gram negative bacteria (endo or exotoxin)? endotoxin
T/F exotoxin is toxic even when present in small smounts TRUE
T/F all gram negative bacteria produce endotoxin because they have LPS in their cell wall TRUE
The classic stages of clinical infections four distinct phases: Incubation period, prodromal stage, period of invasion, convalescent period.
infection stays in 1 location (ex: fungal nail) localized infection
infection in the blood, throughout the body systemic infection
initially in 1 organ and then spreads (ex: TB) focal infection
infection due to more than 1 species of microbe mixed infection
any objective evidence of disease as noted by an observer. sign
the subjective evidence of disease as sensed by the patient symptom
-itis inflammation
-emia blood
-osis a disease or morbid process
-oma tumor (e.g, sarcoma, colorectal carcinoma) or swelling (tuberculoma)
major portals of exit respiratory and salivary portals (coughing, sneezing), skin cells (open lesion), fecal exit, urogenital tract, removal of blood or bleeding
prevalence total number of cases in population/ total number of persons in population x 100 = %
incidence number of new cases/ number of healthy persons = ratio
endemic occurrence disease is restricted to only a certain area
sporadic occurence disease can be anywhere
epidemic occurrence in many areas, with many cases in each area
pandemic occurrence spreads globally everywhere
the primary habitat in the natural world from which a pathogen originates. reservoir
the individual or object from which an infection is actually acquired infection source
A live animal that transmits an infectious agent from one host to another vector
actively participates in a pathogen’s life cycle, serving as a site in which it can multiply or complete its life cycle (such as mosquito). biological vector
not necessary to the life cycle of an infectious agent and merely transport it without being infected (such as fly). mechanical vector
n infection indigenous to animal but naturally transmittable to humans (such as rabies). zoonosis
transmissible from person to person communicable diseases
not transmitted from person to person. non-communicable diseases
any inanimate material commonly used by humans that can transmit infectious agents. (ex: food, blood, water) vehicle
an inanimate object that harbors and transmits pathogens (ex: telephone, door knob, etc) formite
dried microscopic residues created when microscopic pellets of mucus and saliva are ejected from the mouth and saliva droplet nuclei
suspensions of fine dust or moisture particles in the air that contain live pathogens. aerosols
Infectious diseases acquired as a result of a hospital stay. nosocomial infections
the most common nosocomial infections involves: the urinary tract, surgical incisions, and the respiratory tract. Skin, septicemia, and others (meningitis, gastroenteritis) are also involved in nosocomial infections
etiology of a disease is often determined using: Koch's postulates
Created by: flash89



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