Term
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Definition
| quantitative measurement of the pathogenicity or the likelihood of causing disease |
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Term
entry of the pathogen
establishment and multiplication
avoidance of host defenses
damage
exit |
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Definition
| steps in bacterial invasion |
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Term
sepicemia
toxins
enzymes
attachment systems
self destruction
changing antigens
camouflage |
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Definition
| virulence factors of microbes |
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Term
chemistry
mode of action
susceptible organism
spectrum
antibiotic/antimicrobial
effect |
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Definition
| what are ways antibiotics can be classified? |
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Term
beta-lactam antibiotics (penicillin, cephalosporins, carbapenems, monobactams)
glycopeptides (vancomycin) |
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Definition
| inhibitors of cell wall synthesis |
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Term
aminoglycosides
macrolides
tetracyclines
lincosamides (clindamycin)
chloramphenicol
streptogramins
oxazolidiones (linezolid) |
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Definition
| inhibitors of protein synthesis |
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Term
fluoroquinolones
metronidazole |
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Definition
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Term
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Definition
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Term
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Definition
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Term
if the microorganism lacks the receptor for the drug
bacteria often contain the drug receptor but do not respond because the concentration of the antibiotic at the target site is inadequate: ex) the difference in permeability barrier provided by the cell envelops of Gram - and Gram + organisms
escape from the antibiotic effect: sometimes bacteria are sensitive to an antibiotic and sufficient concentrations are achieved at the site of action, but the organism is able to escape the consequences of the drug effect |
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Definition
| methods of intrinsic antimicrobial resistance |
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Term
| selection process of acquired drug resistance |
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Definition
| the relative abundance of resistant organisms in a microbial population increases as continuing antibiotic therapy preferentially eliminates drug sensitive cells |
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Term
antibacterial resistance genes: chromosomal genes are passed directly to daughter cells (clonal spread); clonal spread of the bacteria; genes on plasmids, transposons, and bacteriophages (it can include genes originated from the chromosome) can be transmitted horizontally between bacteria from the same or different species or genera
horizontal gene transfer
selection favors resistant bacterium |
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Definition
| characteristics of bacterial resistance |
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Term
vertical transfer of resistant genes (mutations)
horizontal transfer of genes
transformation: soluble pieces of DNA containing resistance genes are taken up from the environment by a drug sensitive bacteria
transduction: the genes for determining drug resistance are located in the plasmid and this extrachromosomal DNA is transferred from one bacteria to another by a phage (this mechanism is of considerable importance clinically, beta-lactamases are transferred by this method) (most common mechanism for gene exchange and recombination in bacteria)
conjugation: drug resistant genes contained in a plasmid are passed from one cell to another through direct contact
plasmids and transposons |
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Definition
| sources of resistant genes |
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Term
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Definition
| a plasmid that can exist either with or without being integrated into the host chromosome |
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Term
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Definition
| carry genes for pili and can transfer copies of themselves during conjugation |
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Term
| fertility factors or F factors |
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Definition
| carries genes responsible for cell attachment and plasmid transfer between specific bacterial strains during conjugation |
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Term
| resistance factors or R factors |
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Definition
| typically carries genes that code for enzymes capable of destroying or modifying antibacterial agents |
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Term
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Definition
| transformation: bacteria take up fragments of naked DNA and incorporate them into their genome. some species are ( ), naturally taking up exogenous DNA |
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Term
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Definition
| once in a cell, a ( ) can jump between plasmid to plasmid or plasmid to chromosome |
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Term
1) the bacteria produce enzymes such as beta-lactamases that destroy the antimicrobial agent before it reaches its target
2) the bacterial cell wall becomes impermeable to the antimicrobial agent
3) the target site is altered by mutation so that it no longer binds the antimicrobial agent
4) the bacteria possesses an efflux pump that expels the agent from the cell before it can reach the target
5) mutations in bacterial DNA change the target enzyme in a metabolic pathway so that the antimicrobial agent no longer binds to it, or, alternatively, the bacteria acquire new genetic information that codes for an alternate metabolic pathway that no longer utilizes the target enzyme |
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Definition
| mechanisms of acquired antimicrobial resistance |
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Term
fluoroquinolones, tetracyclines, and macrolides
active efflux is an energy dependent process
results in decreased accumulation (as does decreased uptake) |
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Definition
| antibiotics that become ineffective due to active efflux from the bacteria |
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Term
beta lactams through beta-lactamases
aminoglycosides through aminoglycoside-modifying enzymes
chloramphenicol through chloramphenicol acetyltransferase |
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Definition
| antibiotics that become ineffective due to enzymatic inactivation |
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Term
judicious use of antibiotics: antibiotic sensitive tests, follow up of the infection
continuous efforts to control the use of antibiotics in both humans and animals: general public education
combination therapy |
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Definition
| ways to prevent resistance |
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