Term
| Define Antimicrobial Susceptibility Testing |
|
Definition
| use of chemical compounds to treat diseases caused by microorganisms |
|
|
Term
| How are antimicrobials different from antibiotics? |
|
Definition
| Antibiotics produced by another microorganism. Antimicrobials often synthetic or semi-synthetic. |
|
|
Term
| What determines the effectiveness of a drug on bacteria? |
|
Definition
- The mechaism of action
- The absorption, distribution, and excretion of the individual drug
|
|
|
Term
| What are some important factors to take into consideration when prescribing a drug for a bacterial infection? |
|
Definition
- Drug's toxicity (affect liver, kidney, or nervous system)
- Development of resistance
- How a drug is administered (IV vs oral)
- Cost of the drug
|
|
|
Term
| What are 2 ways antimicrobials can attack bacteria? |
|
Definition
- Interruption of structural integrity (cell wall, or cell membrane)
- Interruption of basic metabolic functions
|
|
|
Term
| What is important to consider when prescribing a bacteriostatic drug? |
|
Definition
| Patient must have a competent immune system to complete the destruction of the microorganism. |
|
|
Term
| What is the principle behind the effectiveness of Beta lactams? |
|
Definition
| Bind to enzymes (transpeptidases) critical in the production of the cell wall, inactivating the enzyme. |
|
|
Term
| What are the four types of Beta lactams? |
|
Definition
- Penicillins
- Cepthalothin
- Monobactams
- Carbepenems
|
|
|
Term
| What is the common feature of all Beta Lactam drugs? |
|
Definition
| Have beta lactam ring in their structure. |
|
|
Term
| What types of bacteria should Penicillin be used for? |
|
Definition
- GPC
- GNC
- **Many bacteria resistant to this.
|
|
|
Term
| What types of bacteria should ampicillin be used for? |
|
Definition
- GPC (including Enterococcus)
- some GNB
- Haemophilus
|
|
|
Term
| What types of bacteria should carbepenem be used for? |
|
Definition
| GNB including Ps. aeruginosa |
|
|
Term
| What types of bacteria should cephalosporins be given for? |
|
Definition
- Widest spectrum or organisms
- Affects many GNB that are resistant to many other drugs.
|
|
|
Term
| Which type of Beta Lactam affects the widest spectrum of organisms? |
|
Definition
|
|
Term
| What type of bacteria should monobactams be given for? |
|
Definition
|
|
Term
| What enzyme do bacteria produce that make them resistant to Beta Lactam drugs? |
|
Definition
| Beta lactamase (hydrolyzes the beta lactam ring) |
|
|
Term
| What is a specific chemical that inhibits beta lactamase? |
|
Definition
|
|
Term
| Why is Augmentin effective in bacteria that are resistant to Beta Lactam Drugs? |
|
Definition
| Combines a beta lactam (ampicillin) with a beta lactamase inhibitor (clavulanic acid). |
|
|
Term
| What is the principle behind Vancomycin? |
|
Definition
| Disrupts cell wall at an earlier stage of its synthesis |
|
|
Term
| What types of bacteria is Vancomycin used for? |
|
Definition
| Only gram-positive cocci (Staph aureus) |
|
|
Term
| What are the 3 types of drugs that inhibit protein synthesis in bacteria? |
|
Definition
- Aminoglycosides
- Tetracyclines
- Macrolides
|
|
|
Term
| What is the principle behind aminoglycosides? |
|
Definition
| Bind to the 30S causing a misreading of the genetic code |
|
|
Term
| Are aminoglycosides bacteriocidal or bacteriostatic? |
|
Definition
|
|
Term
| What type of bacteria are aminoglycoside drugs used to combat? |
|
Definition
- GNB including Ps. aerug
- some other non-fermenters that are resistant to many antimicrobials
|
|
|
Term
| What is an example of a widely used aminoglycoside drug? |
|
Definition
|
|
Term
| What are 2 disadvantages to Aminoglycoside drugs? |
|
Definition
- IV antimicrobial
- Kidney toxicity
|
|
|
Term
| What is the principle behind the drug, Tetracycline? |
|
Definition
| Resversibly binds to the 30S spot on bacterial ribosome. |
|
|
Term
| Are Tetracylclines bacteriostatic or bacteriocidal? |
|
Definition
|
|
Term
| What kinds of pathogens are tetracycline drugs used for? |
|
Definition
|
|
Term
| What are some examples of Macrolide drugs? |
|
Definition
- Erythromycin
- Azithromycin
- Clindamycin
- Chloramphenicol
|
|
|
Term
| What is the principle behind macrolide drugs? |
|
Definition
| Binds to 50S portion of bacterial ribosome. |
|
|
Term
| Are macrolide drugs bacteriostatic or bacteriocidal? |
|
Definition
|
|
Term
| What kind of infections is the drug azithromycin most commonly used for? |
|
Definition
| Upper Respiratory Tract infections |
|
|
Term
| What kinds of bacteria is erythromycin most effective against? |
|
Definition
- Gram positive
- Also effective against some GNB like Haemophilus and Moraxella
|
|
|
Term
| What types of bacteria is clindamycin used to treat? |
|
Definition
- Gram positives
- some GNB like Haemophilus and Moraxella
- Anaerobes
- Some protozoa like malaria
|
|
|
Term
| What is the principle behind drugs that inhibit essential metabolites? |
|
Definition
| Inhibit essential enzymes that bacteria need to make folinic acid (which in turn is used to synthesize DNA). |
|
|
Term
| What type of drug was the first broad spectrum antimicrobial drugs developed? |
|
Definition
|
|
Term
| What is the beginning of the folinic acid --> DNA pathway? |
|
Definition
| para-amino-benzoic acid (PABA) |
|
|
Term
| What drug has the acronym SXT? |
|
Definition
|
|
Term
| What drug is used in conjugation with sulfonamides to produce a synergistic effect? |
|
Definition
|
|
Term
| Are sulfonamides bacteriostatic or bacteriocidal? |
|
Definition
|
|
Term
| What types of bacteria is Bactrim used for? |
|
Definition
- Gram positive
- Gram negative
|
|
|
Term
| What types of infections is Bactrim used for? |
|
Definition
- UTI's
- One of the few effective drugs for B. cepacia
- ** Not effective for Ps. aeruginosa
|
|
|
Term
| What are some examples of drugs that are inhibitors of nucleic acid metabolism? |
|
Definition
- Rifampin
- Quinolones
- Ciprofloxicin
- Naladixic acid
- Metronidazole (Flagyl)
|
|
|
Term
| Are inhibitors of nucleic acid metabolism bacteriostatic or bacteriocidal? |
|
Definition
|
|
Term
| What is the principle of Rifampin and what bacteria is it used to combat? |
|
Definition
| Affects RNA metabolism of M. tuberculosis |
|
|
Term
| What types of bacteria are quinolones used for? |
|
Definition
| Gram positive and negative |
|
|
Term
| Why can't quinolones be prescribed to children? |
|
Definition
| Affects cartilage production |
|
|
Term
| What is the principle behind quinolone drugs? |
|
Definition
|
|
Term
| What types of bacteria is Cirpofloxcin used to treat? |
|
Definition
|
|
Term
| What is the principle behind the activity of the metronidazole drug? |
|
Definition
| Affects the actual DNA molecule |
|
|
Term
| What types of bacteria is metronidazole primarily used for? |
|
Definition
- Gram negative anaerobes
- Trichomonas
|
|
|
Term
| What is one bad side effect of metronidazole? |
|
Definition
| Leaves a metallic taste in mouth. |
|
|
Term
| What are 3 mechanisms of bacterial resistance? |
|
Definition
- Prevent access to the target
- Modification of the target
- Production of inactivating enzymes to the antimicrobial
|
|
|
Term
| Whether or not to do susceptibility testing depends on which factors? |
|
Definition
- Source of specimen
- Isolation of a pure culture vs. mixed culture
- host status
|
|
|
Term
| Approximately how many antimicrobials are there to choose from for susceptibility testing? |
|
Definition
|
|
Term
| What 3 factors determine which drug panel is chosen for susceptibility testing? |
|
Definition
- Patient population
- Specimen type
- Organism itself
|
|
|
Term
| What are the three most commonly used panels in an automated system? |
|
Definition
- Gram pos
- Gram neg
- Urinary isolates
|
|
|
Term
| What are the types of susceptibility testing methods? (3 main ones) |
|
Definition
- Kirby Bauer
- Microtiter Test Panels
- E test
|
|
|
Term
| What type of media is used in the Kirby Bauer test? |
|
Definition
|
|
Term
| What is the principle behind the Microtiter test panels for susceptibility testing? |
|
Definition
| Each panel uses a number of drugs with a variety of concentrations of each drug in each microwell of panel |
|
|
Term
| What are two ways microtiter plates for susceptibility testing can be stored? |
|
Definition
|
|
Term
|
Definition
- Minimum inhibitory concentration
- First well showing no bacterial growth
|
|
|
Term
| There are automated microtiter test panels for susceptibility testing of which organisms? |
|
Definition
- Staph spp.
- Eneterococcus spp.
- Enterobacteriaceae
|
|
|
Term
| "Trailing" occurs when which drug is tested using the microtiter plate susceptibility test? |
|
Definition
|
|
Term
| Which result is considered the MIC when "trailing" is observed in microtiter susceptibility testing? |
|
Definition
| The result that is 80% reduction in growth as compared to the growth control |
|
|
Term
| Which drugs can be used against Ps. aeruginosa? |
|
Definition
- Carbepenem
- Aminoglycosides (gentamicin plus ampicillin)
- Ciprofloxicin
|
|
|
Term
| What is one of the only drugs useful for B. cepacia? |
|
Definition
|
|
Term
| What is the principle behind the E susceptibility test? |
|
Definition
| Strip with many concentrations of the drug set up on an MH plate. Read where the arc of inhibition intersects the strip. |
|
|
Term
| What kinds of bacteria is the E test commonly used for during susceptibility testing? |
|
Definition
- Anaerobes
- Strep. pneumoniae
- Fastidious organisms
|
|
|
Term
| All Staph spp that are resistant to penicillins produce what? |
|
Definition
| Penicillin binding proteins (PBP) |
|
|
Term
| What gene codes for resistance to penicillins? |
|
Definition
|
|
Term
| What is heteroresistance? |
|
Definition
| All cells have the gene, but not all express it so some colonies will show resistance and some will show susceptibility |
|
|
Term
| What plate is used to screen for MRSA? |
|
Definition
|
|
Term
| Besides an oxycillin screen plate, what other test can be done for detecting MRSA? |
|
Definition
Disk difusion test (KB)
Gives better correlation |
|
|
Term
| A D test must be performed when? |
|
Definition
| Staph shows resistance to erythromycin and susceptibility to clindamycin |
|
|
Term
| If the D test is positive, how should the result be reported out? |
|
Definition
| Inducible resistance to clindamycin |
|
|
Term
| What media is used for screening for VRE? |
|
Definition
| Vancomycin screening plate (BHI plus vancomycin) |
|
|
Term
| What are Extended Spectrum Beta Lactamases (ESBL)? What organisms are included in this catgegory? |
|
Definition
Resistant to later generations of Beta Lactamases (ampicillin, cephalosporins, and aztreonam)
Bacteria: K. pneumoniae, K. oxytoca, E. coli |
|
|
