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145 Cards in this Set
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How antibiotic resistance happens: 4 steps |
1) There are lots of germs --> a few are drug resistant 2) Antibiotics kill bacteria that are causing the illness and the good bacteria that protect the body from infection 3) The drug-resistant bacteria are now allowed to grow and take over 4) Some bacteria give their drug-resistance to other bacteria, causing more problems |
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1 Example of how antibiotic resistance spreads through animals |
1) Animals get antibiotics in their food and develop resistant bacteria in their guts -drug resistant bacteria remain on meat of the animals and (if the food is not handled or cooled properly) the bacteria spread to humans
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1 Example of how antibiotic resistance spreads through people |
2) Person gets antibiotics and develops resistant bacteria in his gut -George gets care at a hospital -Resistant bacteria spread to other patients from surfaces within the hospital or through the unclean hands of healthcare providers |
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Where antibiotics come from |
Come primarily from microorganisms that produce substances by the natural metabolic processes that inhibit or destroy other microorganisms |
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Some traits of the ideal antimicrobial drug (6) |
-Selectively toxic to the microbe but nontoxic to host cells -Microbicidal rather than microbistatic -Relatively soluble; functions even when highly diluted in body fluids -Doesn't lead to development of antimicrobial resistance -Complements or assists the activities of the host's defenses -Does not disrupt the host's health by causing allergies or predisposing the host to other infections |
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Def. of chemotherapeutic drug |
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Prophylaxis |
Use of a drug to prevent potential for infection of a person at risk |
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Antimicrobial chemotherapy |
The use of chemotherapeutic drugs to control infection
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Antimicrobials |
All-inclusive term for any antimicrobial drug, regardless of its origin |
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Antibiotics |
Substances produced by the natural metabolic processes of some microorganisms that can inhibit or destroy other microorganisms |
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Semisynthetic drugs |
Drugs that are chemically modified in the laboratory after being isolated from natural sources |
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Synthetic drugs |
The use of chemical reactions to synthesize antimicrobial compounds in the laboratory |
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Narrow spectrum (limited spectrum) |
Antimicrobials effective against a limited array of microbial types -For example, a drug effective mainly on Gram + bacteria |
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Broad spectrum (extended spectrum) |
Antimicrobials effective against a wide variety of microbial types -For example, a drug effective against both Gram + and Gram - bacteria |
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Penicillium sp. is a type of ... and produces the drugs (2) |
-Type of mold -Produces Penicillins and Griseofulvin |
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Cephalosporium is a type of... and produces the drugs |
-Type of mold -Produces Cephalosporins |
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Micromonospora is a type of... and produces the drug |
-Type of bacteria -Produces Gentamicin |
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Bacillus sp. is a type of... and produces the drugs (2) |
-Type of bacteria -Produces Bacitracin and Polymixin B |
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Chromobacterium is a type of... and produces the drug |
-Type of bacteria -Produces Aztreonam |
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Streptomyces is a type of... and produces the drugs (6) |
-Type of filamentous bacteria -Produces 1) Streptomycin 2) Erythromycin 3) Tetracycline 4) Vancomycin 5) Chloramphenicol 6) Amphotericin B |
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5 Mechanisms of action of drugs |
1) inhibition of cell wall synthesis 2) Breakdown of the cell membrane structure or function 3) Inhibition of structure or functions of DNA and RNA 4) Inhibition of protein synthesis 5) Blocks key metabolic pathways |
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Drugs that are cell wall inhibitors (6) |
--> Block synthesis and repair 1) Penicillins 2) Cephalosporins 3) Monobactams (Aztreonam) / Carbapenems (Imipenem) 4) Vancomycin 5) Bacitracin 6) Isoniazid (INH)
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Drugs that target the cell membrane |
--> Cause loss of selective permeability 1) Polymyxins |
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Drugs that target DNA/RNA (2) |
--> Inhibit replication and transcription 1) Quinolones (Fluoroquinolones) 2) Rifampin |
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Drugs that inhibit protein synthesis (4) |
1) Aminoglycosides 2) Tetracycline 3) Chloramphenicol 4) Macrolides
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Drugs that block metabolic pathways and products (2) |
1) Sulfonamides (sulfamethoxazole) 2) Trimethoprim |
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About the cell wall of bacteria |
-Contains a rigid girdle of peptidoglycan which protects the cell from hypotonic environments -Cells must continue to make the peptidoglycan |
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How drugs target the cell wall |
Drugs such as penicillins and cephalosporins bind and block peptidases which form the cell wall's cross bridges
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The effect of this action |
The cell wall has no strength so it is more susceptible to changes in osmolarity and pH and the cell lyses |
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Drugs that target the cell wall are considered |
Bactericidal |
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There are 2 groups of drugs that target the cell wall: |
1) Beta-lactam drugs 2) Non Beta-lactam cell wall inhibitors
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Beta-lactam drugs (4) |
1) Penicillin 2) Cephalosporin 3) Imipenem (carbapenems) 4) Aztreonam (monobactams) |
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Non Beta-lactam drugs |
1) Vancomycin 2) Bacitracin 3) Isoniazid (INH) |
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Features of the beta-lactam group of antibiotics |
Contain a 3-Carbon, 1-Nitrogen ring that is highly reactive (beta-lactam ring) |
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Role of Beta-lactam antibiotics |
Interfere with cell wall synthesis, leading to lysis |
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Amount of Beta-lactam antibiotics |
More than 1/2 of all antibiotics are beta-lactams |
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Penicillinases / Betalactamases and how they work |
-Exoenzymes produced by may bacteria that are capable of destroying the beta-lactam ring of penicillin (inactivate the antibiotic) -Cleave the beta-lactam ring |
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Penicillins |
Large diverse group of compounds which end in the suffix -cillin |
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Penicillins are produced by |
microbial fermentation of the mold Penicillium chrysogenum |
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All penicillins consist of 3 parts |
1) Beta-lactam ring 2) Thiazolidine ring 3) Variable side chain that dictates its microbicidal activity
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Natural penicillins (2) |
1) Penicillin G 2) Penicillin V |
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Penicillin G (4) |
-First antibiotic made from mold and is the parent for all "cillins" -Acid labile (can be destroyed by acid) so its given IM -Penicillinase sensitive (penicillinase can cleave it) -Narrow spectrum (Streptococci --> Gram +, meningococci -->Gram -, syphilis) |
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Penicillin V |
-Can be taken orally, acid stable -Penicillinase sensitive -Narrow spectrum |
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Semisynthetic penicillins |
1) Oxacillin/Dicloxacillin 2) Methicillin/Nafcillin 3) Ampicillin/Amoxicillin 4) Carbenicillin/ Ticarcilllin |
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Oxacillin / Dicloxacillin (6) |
-Narrow spectrum -Not susceptible to penicillinase -Good absorption -Has chemically altered side chain that extends spectrum -Used to treat infections from penicillinase producing Staph. -Resistance developing |
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Methicillin / Nafcillin (4) |
-Narrow spectrum -Not susceptible to penicillinase -Poor absorption, given IM or IV -Resistance extensive (MRSA) (Not used any more/ineffective) |
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Ampicillin / Amoxicillin (4) |
-Broad spectrum to include Gram - pathogens (H. influenzae, P. mirabilis, E. coli) -Sensitive to penicillinase -Not used much against Gram +'s because Pen G and V are cheaper -Amino penicillin |
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Carbenicillin / Ticarcillin (3) |
-Broad to very broad spectrum (more Gram - coverage) -Effective against Pseudomonas sp. (Gram - that is very hard to treat) -Sensitive to penicillinase |
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About Augmented Penicillins |
Calvulanic acid is a chemical that inhibits beta-lactamase enzymes (enzymes that work against Beta-lactam antibiotics), thereby increasing the longevity of beta-lactam antibiotics in the presence of penicillinase-producing bacteria |
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Calvulanic acid is added to |
Semisynthetic penicillins to augment their effectiveness |
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Example of an augmented penicillin |
Amoxicillin + Clavulanate (calvulanic acid) = Augmentin |
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The Cephalosporins (relation to penicillins) |
Similar to penicillins in that they have a Beta-lactam structure that can be synthetically altered and so they have a similar mode of action |
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Numbers of Cephalosporins |
Account for 1/3 of all antibiotics administered |
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About Cephalosporins |
-Broad spectrum -Resistant to most penicillinases -Fewer allergies |
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Some bacteria produce...which acts against cephalosporins |
Cephalosporinase |
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Cephalosporins are adminstered |
IV or IM |
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About the generations of cephalosporins |
Four generations exist and each gen. is more effective against Gram - than the gen. before |
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Discriptions of the 4 generations |
1) 1st generation - most effective against Gram + cocci, few Gram - 2) 2nd generation - better Gram - effects 3) 3rd generation - work against enteric bacteria that produce beta-lactamases 4) 4th generation - very broad spectrum against many Gram + and Gram -'s |
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Carbapenems group includes the antibiotic |
Imipenem
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Imipenem is produced by |
A mold called Streptomyces cattleya |
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Imipenem is a |
Potent broad spectrum antibiotic |
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Imipenem is used for |
Infections with aerobic and anaerobic pathogens |
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Imipenem is given |
IV or orally |
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Plus side of Imipenem |
Is stable in the presence of beta-lactamases |
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Imipenem is also known as |
Primaxin |
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Monobactams include the drug |
Aztreonam |
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Aztreonam is a |
Narrow spectrum drug |
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Aztreonam is used for |
-Infections by Gram - aerobic bacilli -People who are allergic to penicillin -Pneumonia -Septicemia -UTI's |
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Non Beta-Lactam cell wall inhibitors (3) |
-Vancomycin -Bacitracin -Isoniazid (INH) |
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Vancomycin is a |
Narrow spectrum drug |
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Vancomycin is used for |
-MRSA infections -Clostridium difficile -Enterococcus endocarditis |
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Downside of Vancomycin |
Toxic and hard to give (restricted to most serious, life threatening conditions) |
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Bacitracin is a |
Narrow spectrum drug |
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Bacitracin is produced by |
Bacillus subtilis |
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Bacitracin is found in |
Neosporin (antibiotic ointment) |
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Bacitracin is used for |
Superficial skin infections with streptococci and staphylococci |
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Isoniazid (INH) is used for |
Treating patients with tuberculosis |
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Isoniazid is only effective... |
Against growing cells |
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Isoniazid is often prescribed with |
Rifampin |
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TB treatment includes |
Rifater -INH -Rifampin -Pyrazinamide |
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How antibiotics that damage bacterial cell membranes work |
Cause cell to die from disruption in metabolism or lysis |
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Class of drugs that target the cell membrane |
Polymyxins |
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Polymyxin is |
Narrow spectrum |
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How polymyxins work |
Binds to the cell membrane and forms abnormal openings that cause the membrane to become leaky |
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Polymyxins are used for |
-Pseudomonas infections (Gram -) -UTI's |
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Polymyxins are also |
Topical agents |
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2 Polymyxin antibiotics are |
-Polymyxin B -Polymyxin E |
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Downside of Polymyxins |
Toxic to kidneys |
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3 ways that drugs that target nucleic acids work |
-Block synthesis of nucleotides -Inhibit replication -Stop transcription
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Drugs that target nucleic acids (2) |
-Fluoroquinolones (class) -Rifampin (AB) |
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Fluoroquinolones (flu-row-quin-oh-lones) work by |
Binding enzymes essential for DNA replication (enzymes needed to unwind DNA) |
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Fluoroquinolones are |
Broad spectrum |
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Fluoroquinolones are not good for |
Anaerobes |
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Plus side of fluoroquinolones |
Readily absorbed |
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Fluoroquinolones are used for (6) |
-UTI's -STD's -GI infections -Osteomyelitis -Respiratory infections -Soft tissue infections |
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CDC's recommendation on fluoroquinolones |
Recommends monitoring to prevent resistance |
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Drugs in the fluoroquinolone class |
-Norfloxacin -Ciprofloxacin (For patients leaving hospital and coming off IV antibiotics) |
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Rifampin works by |
Blocks RNA polymerase, preventing transcription |
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Rifampin is used in |
-TB therapy -Leprosy -Prophylaxis for N. meningitidis exposure (this is a fatal dz. easily transmitted to health care workers via mouth to mouth...Rifampin is given to treat people who have come in contact with this dz. but didn't know when giving treatment) |
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Drugs that interfere with protein synthesis (4) |
1) Aminoglycosides 2) Tetracycline 3) Chloramphenicol 4) Macrolides |
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How drugs that target protein synthesis work |
Most drugs react with the ribosome / mRNA complex to inhibit protein synthesis |
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Aminoglycosides work by |
binding to one of the ribosomal subunits so that mRNA is misread |
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Aminoglycosides are |
Bactericidal |
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Aminoglycosides are produced by (2) |
Streptomyces and Micromonospora (actinomycetes) |
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Aminoglycosides are |
Broad spectrum |
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3 Drugs that are Aminoglycosides and what they are each used for |
1) Streptomycin - TB, plague 2) Gentamicin - Gram -'s 3) Tobramycin/amikacin - pseudomonas infections |
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Downside of aminoglycosides (2) |
-Renal tubular damage -Ototoxicity |
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Tetracycline (AB) is a |
(First truly) broad spectrum Ab |
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Tetracycline is |
Bacteriostatic |
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Tetracycline works by |
Inhibits protein synthesis by preventing attachment of the amino acids carried by tRNA (by binding to ribosomes) |
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Tetracycline is used for |
-Chlamydia -Rickettsia |
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2 Downsides of Tetracycline |
-Inhibits normal flora -Deposits on growing bones and teeth |
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Tetracycline cannot be used for (2) |
-Children -Pregnant women |
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Chloramphenicol is |
Broad spectrum against many Gram -'s |
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Chloramphenicol is |
Bacteriostatic |
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Chloramphenicol works by |
Preventing peptide bond formation in protein synthesis |
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Chloramphenicol is used for (4) |
-Anaerobes -H. influenzae -Meningitis -Typhoid fever |
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Downside of Chloramphenicol |
Toxic to human cells...causes aplastic anemia when person is on long term therapy with this drug (suppresses bone marrow so RBC production decreases) |
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Patients on Chloramphenicol need... |
To be monitored during therapy |
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2 drugs that are Macrolides |
1) Erythromycin 2) Clindamycin |
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Erythromycin is also known as (2) |
1) Azithromycin (Z packs) 2) Clarithromycin |
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Erythromycin is a |
Moderate to broad spectrum drug |
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Erythromycin is used for (3) |
-Mycoplasma (co-infector with STD's and causes walking pneumonia) -Legionnaires disease -Cell wall defective microorganisms |
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Erythromycin works by |
Inhibits translocation by attaching to 50s unit |
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Erythromycin is |
Bacteriostatic |
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Erythromycin is good for |
Patients who are allergic to Penicillin or penicillin resistant bacteria |
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Clindamycin is used for (3) |
-Anaerobic infections (like C-diff) -Penicillin resistant Staph -Acne |
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How drugs that block metabolic pathways work |
Mimic normal substrate of an enzyme through competitive inhibition (supplied to enzyme instead of true substrate so the enzyme cannot produce needed product) |
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Drugs that block metabolic pathways |
1) Trimethoprim 2) Sulfamethoxazole (sulfonamides) |
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How sulfonamide drugs work |
Block the bacterial synthesis of folic acid (necessary for bacteria) |
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How trimethoprin works |
Inhibits a second enzymatic step in the synthesis of folic acid |
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Trimethoprim- Sulfamethoxazole |
Given in combination to take advantage of the synergistic effect of the 2 drugs |
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Trimethoprim - Sulfamethoxazole is used for (3) |
-PCP (mold that we breathe in) treatment with AID's patients -UTI's -Otitis media (ear infections)
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Trimehtoprim - Sulfamethoxazole is also known as (2) |
1) Bactrim 2) Septra |
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Newly developed classes of antimicrobials come from |
Pre-existing drug classes |
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5 types of new drug types |
1) Fosfomycin trimethamine 2) Synercid 3) Daptomycin 4) Ketolides 5) Oxazolidinones |
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Fosfomycin Trimethamine is used for...and works by... |
-A phosphoric acid effective as alternate treatment for UTI's -Inhibits cell wall synthesis |
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Synercid is used for (2)...and works by... |
-Effective against Staphylococcus and Enterococcus that cause endocarditis and surgical infections -used when bacteria is resistant to other drugs -Inhibits protein synthesis |
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Daptomycin is used for... and works by... |
-Used mainly for Gram + -Disrupts membrane function |
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Ketolides include the antibiotic |
Telitromycin (Ketek) |
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Ketolides are used for |
Infections when resistant to macrolides |
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Ketolides are similar to the drug... |
Erythromycin but have different ring structure |
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Oxazolidinones include the drug |
Linezolid (Zyvox) |
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How oxazolidinones work |
(Synthetic antimicrobial) that blocks the interaction of mRNA and ribosome |
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Oxazolidinones are used for |
Used to treat methicillin resistant Staphylococcus aureus (MRSA) and vancomycin resistant Enterococcus (2 of the most difficult clinical pathogens) |
