Anti Microbial Flashcards
What are the classifications of antimicrobials based on structure?
• B-lactams
• Aminoglycosides
• Tetracyclines
• Sulfonamides
• Fluoroquinolones
These classifications help in identifying the type of antimicrobial based on their chemical structure.
What is the difference between CIDAL and STATIC antimicrobials?
CIDAL kill microorganisms; STATIC inhibit growth
CIDAL agents are essential for treating infections in immunocompromised patients, while STATIC agents are not.
Which antimicrobial classes are considered CIDAL?
• Beta lactams
• Vancomycin
• Fluoroquinolones
• Aminoglycosides
CIDAL agents are necessary for effective treatment in immunocompromised individuals.
What are the classifications of antimicrobials based on source?
• Antibiotics (from microorganisms)
• Non-antibiotics (any other)
This classification distinguishes between natural and synthetic antimicrobials.
List the classifications of antimicrobials based on organism.
• Antibacterial
• Antiviral
• Antifungal
• Antiprotozoal
• Antihelmintic
Each classification targets a specific type of pathogen.
What are the main mechanisms of action for antimicrobials?
• Cell wall inhibitors
• Protein synthesis inhibitors
• Metabolism inhibitors
• DNA gyrase inhibitors
• Drugs acting on membranes
Understanding the mechanism of action is crucial for effective treatment.
What are examples of cell wall inhibitors?
• Fosfomycin
• Beta lactams
• Bacitracin
• Cycloserine
• Vancomycin
These drugs target the bacterial cell wall, disrupting its synthesis.
Which antimicrobials bind to 30S ribosomes?
• Aminoglycosides
• Tetracyclines
These agents inhibit protein synthesis by targeting the ribosomal subunit.
Which antimicrobials bind to 50S ribosomes?
• Chloramphenicol
• Macrolides
• Clindamycin
• Quinpristin
• Linezolid
These agents also inhibit protein synthesis but target a different ribosomal subunit.
What are the examples of metabolism inhibitors?
• Sulfonamides
• Trimethoprim
• Pyrimethamine
These agents interfere with the metabolic processes of microorganisms.
What are DNA gyrase inhibitors?
• Fluoroquinolones
• Nalidixic acid
These drugs inhibit an enzyme essential for DNA replication in bacteria.
Name some drugs that act on membranes.
• Daptomycin
• Polymyxin B
• Polymyxin E
These agents disrupt the integrity of microbial cell membranes.
True or False: Anti-microbial drug resistance can be either intrinsic or acquired.
True
Understanding resistance mechanisms is crucial for effective treatment strategies.
What is acquired resistance in antimicrobial agents?
It means earlier the bacteria was sensitive to the drug but later developed resistance.
What is one mechanism of drug resistance that involves the development of inactivating enzymes?
Enzymes
Seen in drugs such as Aminoglycosides, B-Lactams, and Chloramphenicol
What happens in the altered drug target mechanism of drug resistance?
Bacteria changes the target on which the drug acts
Seen in MRSA, VRSA, and Fluoroquinolones
What is the role of efflux pumps in drug resistance?
They push out the drug once it enters the bacteria
Seen in Tetracyclines and Tigecycline
What is altered metabolism in the context of drug resistance?
Bacteria start using preformed folic acid
Seen in Sulfonamides
What does a decrease in permeability refer to in drug resistance?
It refers to the reduced ability of the drug to enter the bacteria
Seen in Aminoglycosides
What are the two types of transfer of drug resistance?
- Vertical transmission
- Horizontal transmission
What is vertical transmission of drug resistance?
It is the transfer of resistance from one generation to the next generation by mutation.
What is horizontal transmission of drug resistance?
It is the transfer of resistance from one bacteria to another in the same generation
Occurs by Conjugation, Transduction, or Transformation
What is conjugation in bacteria?
Conjugation is when one bacteria transfers resistance to another through physical contact called sex pilli.
This is the most common method of horizontal transfer.
What is transduction in the context of bacterial resistance?
Transduction is the transfer of resistance from one bacteria to another with the help of a virus called bacteriophage.
Bacteriophages are viruses that infect bacteria.
Define transformation in bacterial resistance.
Transformation is the transfer of resistance by free environmental DNA.
This is the least common method of horizontal transfer of drug resistance.
What is pseudomembranous colitis?
Pseudomembranous colitis is a type of superinfection.
It is primarily associated with Clostridium difficile.
Which bacteria is most commonly involved in pseudomembranous colitis?
Clostridium difficile.
This bacterium is a significant cause of antibiotic-associated diarrhea.
What are the most common antimicrobials implicated in pseudomembranous colitis?
3rd Gen. Cephalosporins, Clindamycin, Fluoroquinolones, Ampicillin, Amoxicillin.
These antibiotics can disrupt normal gut flora, leading to overgrowth of C. difficile.
What is the drug of choice (DOC) for treating pseudomembranous colitis?
Fidaxomicin.
Fidaxomicin has low chances of relapse.
What are alternative treatments for pseudomembranous colitis?
Oral vancomycin, Metronidazole.
These alternatives are used if Fidaxomicin is not available or suitable.
What monoclonal antibody is used against the toxin in pseudomembranous colitis?
Bezlotoxumab.
It is used to reduce the risk of recurrence of infection.
Which bacteria are resistant to cell wall inhibitors?
Mycoplasma, MRSA.
These bacteria lack a cell wall, making them resistant to beta-lactam antibiotics.
What is the first-line treatment for MRSA?
Vancomycin (for treatment).
Vancomycin is usually the drug of choice for serious MRSA infections.
What is the drug of choice for treating Mycoplasma infections?
Macrolides.
Macrolides are effective due to their mechanism of action on protein synthesis.
What combination of drugs is effective against Pseudomonas?
Aminoglycoside + Ceftazidime.
This combination is often used for serious infections caused by Pseudomonas aeruginosa.
What is the treatment for enteric fever?
Ceftriaxone.
Ceftriaxone is commonly used for its effectiveness against Salmonella species.
What is the recommended treatment for anaerobes?
Metronidazole.
Metronidazole is effective against various anaerobic bacteria.
Fill in the blank: Vancomycin is not effective against _______.
Mycoplasma.
Mycoplasma lacks a cell wall, making vancomycin ineffective.
What are the three types of killing mechanisms for bactericidal drugs?
Concentration dependent killing (CDK), Time dependent killing (TDK), Area under curve (AUC) dependent killing (AUC-DK)
These mechanisms describe how the effectiveness of antimicrobial agents varies with drug concentration and duration of exposure.
What characterizes Concentration Dependent Killing (CDK)?
At higher concentration more killing activity, given as a single high dose
CDK is typically followed by aminoglycosides (AG) and fluoroquinolones (FQ).
What characterizes Time Dependent Killing (TDK)?
Killing activity depends on time for which concentration of drugs remains above MBC, given as multiple small doses
TDK is typically followed by beta-lactams and vancomycin.
What is the Post Antibiotic Effect (PAE)?
Time for which bacteria is not able to show growth even when concentration of antimicrobial is below MIC
PAE applies to both CIDAL and STATIC drugs.
Which drugs typically have a short PAE (<90 min) against gram negative bacteria?
B-lactams (except carbapenems) and vancomycin
Short PAE indicates a quicker recovery of bacterial growth after antibiotic removal.
Which drugs typically have a long PAE (>90 min) against gram negative bacteria?
DNA inhibitors (e.g. FQ), Protein synthesis inhibitors (e.g. Tetracyclines, Macrolides, Clindamycin, Aminoglycosides, Carbapenems)
Long PAE allows for prolonged antibacterial effect even after the drug concentration falls below the MIC.
