Chapter 38, 39, 40 (Learning Outcomes) Flashcards
What is a narrow-spectrum antibacterial drug effective against?
Effective against only a few specific bacteria
What is a broad-spectrum antibacterial drug effective against?
Effective against many types of bacteria
What are three examples of bacteriostatic drugs?
- Sulfonamides
- Erythromycin
- Tetracyclines
Define selective toxicity
The ability to suppress or kill an infecting microbe without injury to the host
What are the two ways that drug-resistant microbes develop?
- Spontaneous mutation
2. Conjugation (transfer of genetic material)
What are the classifications by mechanism of action for antimicrobial drugs (6)?
- Inhibition of bacterial cell wall synthesis
- Inhibition of protein synthesis
- Inhibition of nucleic acid synthesis
- Inhibition of metabolic pathway
- Disruption of cell wall permeability
- Inhibition of viral enzymes
How do some antimicrobial affect the cell wall synthesis of certain microbes?
Drugs weaken the cell wall, allowing the cell to absorb water and rupture
= leads to cell death (lysis)
How do some antimicrobial affect the protein synthesis of certain microbes?
Drugs disrupt the bacteria protein synthesis process
- without affecting the protein synthesis in human cells
How do some antimicrobial affect the metabolic pathways of certain microbes?
Nucleic acid synthesis requires folic acid
- microbes must synthesize it
- drugs can act to inhibit folic acid synthesis
How do some antimicrobial affect the cell wall permeability of certain microbes?
Drugs that disrupt the integrity of the bacterial cell wall
- cause the cell to leak the components that are vital to its survival
What is a nosocomial infection?
An infection that originates or occurs in a hospital (or hospital like setting)
What are the 7 considerations for selecting antimicrobial therapy?
- Identification of the pathogen
- Drug susceptibility
- Drug spectrum
- Drug dose
- Time to affect the pathogen
- Site of infection
- Patient assessment
Define empiric therapy
Prescribing antibiotic treatment before the pathogen has been definitely indentified
What is the most common test to identify drug susceptibility?
Culture and sensitivity
What is the course of action if multiple microbes are though to be the causative agent?
A culture specimen of the infected area should be taken BEFORE treatment
- antimicrobials might make identification difficult
What does the culture determine? What does the sensitivity determine?
Culture = determines the identity of the microbe Sensitivity = determines which antimicrobial agent will be therapeutic
Why is it important to choose a drug with the narrowest possible spectrum?
The benefit of a narrow-spectrum antimicrobial agent is that it limits the potential for adverse effects
- such as a superinfection
What is a superinfection?
An infection that occurs during the course of treatment for a primary infection
- ex: antibiotics keep in check ALL microbes (even the good ones) - could give an opportunistic resistant microbe the chance to multiply
What are two possible consequences of NOT using narrow-spectrum antibiotics?
- Secondary infections
2. Development of drug-resistant microbes
When should antibiotics be used prophylactically (5)?
- Exposure to sexually transmitted diseases
- Recurrent UTIs
- Neutropenia (low levels of neutrophils)
- Surgery (GI)
- Bacterial endocarditis (bacteria in the heart)
True or False:
Prophylactic use of antibiotics may contribute to the development of resistant organisms
True
Why is it important to educate patients on taking the FULL dose and duration of an antibiotic treatment?
Stopping therapy early may result in reinfection with the same pathogen
- pathogen will probably have become more drug resistant as a result of inadequate treatment
True or False:
Immunocompromised patients should receive drugs that are quickly bacteriostatic because of patients’ immune responses are limited
False
- they should receive bacterioCIDAL drugs b/c their immune systems are compromised
What body systems must be taken into account when administering antibiotics?
- Liver
- Kidneys
- patient might have difficulty metabolizing or excreting the drug
What adjustment should be made when prescribing an antibiotic to an elderly patient?
Lowering the dose
- minimize the risk for toxicity
Why are nosocomial infections so difficult to treat (3)?
- high prevalence of pathogens
- high prevalence of compromised hosts
- efficient mechanism of transmission
What is the minimum inhibitory concentration (MIC)?
The minimum concentration of an antibiotic that completely suppresses bacterial growth
What is the minimum bactericidal concentration (MBC)?
Concentration of an antibiotic that kills 99.9% of the initial inoculum in a broth dilution
What is the most important element of patient education regarding antibiotics?
Take the entire course of therapy
- taking the prescribe dose at the prescribed intervals
What is the prototype drug for the penicillin drugs?
Penicillin G
- narrow spectrum
What are the different classifications of penicillin (4)?
- Narrow-spectrum penicillin
- Aminopenicillin
- Extended-spectrum penicillin
- Penicillinase-resistant penicillian
What do beta-lactamases do?
Enzymes that disrupt the beta-lactam ring
- inactivates beta-lactam drugs
What should you recommend to your patient if they are allergic to penicillin?
Suggest that they never take an “cillin” drug
- they might be allergic to it as well
What are the two broad-spectrum aminopenicillins?
- Ampicillin
2. Amoxicillin
What are the two extended-spectrum penicillins?
- Piperacillin
2. Ticarcillin
How are aminopenicillins different than penicillins?
Effective against gram-negative microorganisms
Why can resistance to beta-lactams (such as penicillin) occur?
Because of the bacteria’s ability to produce beta-lactamase