Podcast
Questions and Answers
Which type of antibiotic is Doripenem?
Which type of antibiotic is Doripenem?
- 1st generation cephalosporin
- Carbapenem (correct)
- 2nd generation cephalosporin
- 3rd generation cephalosporin
How is the mechanism of action of antibiotics best categorized?
How is the mechanism of action of antibiotics best categorized?
Based on the structure of the bacteria
Anti-pseudomonal penicillin includes Piperacillin-tazobactam.
Anti-pseudomonal penicillin includes Piperacillin-tazobactam.
True (A)
Which antibiotic is considered the last resort?
Which antibiotic is considered the last resort?
Which category of antibiotics kills the bacteria?
Which category of antibiotics kills the bacteria?
Fluoroquinolones are especially used for ________.
Fluoroquinolones are especially used for ________.
Beta-Lactam antibiotics inhibit the synthesis of (blank)
Beta-Lactam antibiotics inhibit the synthesis of (blank)
Match the following antibiotics with their types:
Match the following antibiotics with their types:
What are the mechanisms of antibiotic resistance discussed in the content?
What are the mechanisms of antibiotic resistance discussed in the content?
Why is reducing permeability one of the mechanisms of antibiotic resistance?
Why is reducing permeability one of the mechanisms of antibiotic resistance?
Enzymes can inactivate antibiotics, rendering them ineffective. (True/False)
Enzymes can inactivate antibiotics, rendering them ineffective. (True/False)
Match the antibiotic with the correct category it belongs to:
Match the antibiotic with the correct category it belongs to:
Which drugs can be used for MSSA + Strep A infections orally?
Which drugs can be used for MSSA + Strep A infections orally?
Which antibiotic inhibits RNA polymerase?
Which antibiotic inhibits RNA polymerase?
DNA gyrase inhibitors inhibit the ligating portion of the DNA gyrase while increasing the cutting portion, which fragments the DNA into pieces. One example of DNA gyrase inhibitor antibiotics is ___________.
DNA gyrase inhibitors inhibit the ligating portion of the DNA gyrase while increasing the cutting portion, which fragments the DNA into pieces. One example of DNA gyrase inhibitor antibiotics is ___________.
Which drug is a common empiric antibiotic for Pyelonephritis?
Which drug is a common empiric antibiotic for Pyelonephritis?
Trimethoprim inhibits dihydrofolate reductase.
Trimethoprim inhibits dihydrofolate reductase.
What is the most common pathogen for Acute Cystitis?
What is the most common pathogen for Acute Cystitis?
What is the mechanism of action of Polymyxin?
What is the mechanism of action of Polymyxin?
Neisseria gonorrhoeae can spread to joints.
Neisseria gonorrhoeae can spread to joints.
Match the pathogens with the appropriate antibiotics for Community-Acquired Meningitis:
Match the pathogens with the appropriate antibiotics for Community-Acquired Meningitis:
What is the mechanism of action of Levofloxacin?
What is the mechanism of action of Levofloxacin?
What are the three mechanisms by which DNA/RNA material can bring opportunities for bacteria when it gets destroyed?
What are the three mechanisms by which DNA/RNA material can bring opportunities for bacteria when it gets destroyed?
What are the methods of horizontal gene transfer in bacteria?
What are the methods of horizontal gene transfer in bacteria?
Overprescribing antibiotics in hospitals does not contribute to the risk of antibiotic resistance, True or False?
Overprescribing antibiotics in hospitals does not contribute to the risk of antibiotic resistance, True or False?
In conjugation, bacteria connect via a ____.
In conjugation, bacteria connect via a ____.
Match the mechanisms of resistance to antibiotics with their descriptions:
Match the mechanisms of resistance to antibiotics with their descriptions:
Why do we get a sputum culture for a patient with an infection like pneumonia?
Why do we get a sputum culture for a patient with an infection like pneumonia?
What is the purpose of getting a urinary culture for a patient with a UTI?
What is the purpose of getting a urinary culture for a patient with a UTI?
What method is used to determine the minimum inhibitory concentration (MIC) of antibiotics?
What method is used to determine the minimum inhibitory concentration (MIC) of antibiotics?
Match the antibiotics with their categories:
Match the antibiotics with their categories:
Susceptibility testing helps in determining which antibiotics the bacteria are resistant to.
Susceptibility testing helps in determining which antibiotics the bacteria are resistant to.
The following drug can be used in both community and hospital-acquired meningitis:
The following drug can be used in both community and hospital-acquired meningitis:
What is the mechanism of action of Vancomycin?
What is the mechanism of action of Vancomycin?
Which drug is NOT used for pseudomonas infections?
Which drug is NOT used for pseudomonas infections?
Which drug will you give to treat a patient's infection if the antibiotic susceptibility testing shows resistance to the commonly used drug for the particular organism?
Which drug will you give to treat a patient's infection if the antibiotic susceptibility testing shows resistance to the commonly used drug for the particular organism?
A triad of rashes, muscle spasms, and hypotension are side effects of the following:
A triad of rashes, muscle spasms, and hypotension are side effects of the following:
Which of the following is NOT an anti-Pseudomonal antibiotic?
Which of the following is NOT an anti-Pseudomonal antibiotic?
Which of the following can be used conveniently in methicillin-susceptible S. aureus infection of the skin?
Which of the following can be used conveniently in methicillin-susceptible S. aureus infection of the skin?
Which of the following can be used in a pregnant patient with acute cystitis?
Which of the following can be used in a pregnant patient with acute cystitis?
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Study Notes
Introduction & Mechanism of Action
- Antibiotics can be categorized based on the structure of the bacteria they target
- Antibiotics can be either bactericidal (killing the bacteria) or bacteriostatic (inhibiting the growth of the bacteria)
Mechanisms of Action
- Cell Wall Synthesis
- Inhibits the enzymes that synthesize cell wall synthesis
- Limits the wall synthesis, preventing bacteria from dividing properly
- Bacteria become susceptible to materials leaking in or out of the cell, introducing opportunity for bacterial death
- Cell Membrane Integrity
- Creates efflux pumps in the cell membrane, increasing permeability and risk of cell lysis
- Examples: Daptomycin and Polymyxin
- Folic Acid Pathway
- Inhibits nucleotide synthesis of bacteria
- Examples: Sulfamethoxazole (SMX) and Trimethoprim (TMP)
- DNA Integrity
- Increases the formation of reactive oxygen species (ROS), causing damage to DNA, RNA, and/or proteins
- Examples: Metronidazole and Nitrofurantoin
- Messenger RNA Synthesis
- Inhibits RNA polymerase
- Examples: Rifampin (used in tuberculosis)
- DNA Gyrase Function
- Inhibits DNA gyrase, which helps maintain DNA topology
- Examples: Fluoroquinolones (Ciprofloxacin, Levofloxacin, Gemifloxacin, Moxifloxacin)
- Protein Synthesis Inhibitors
- 50S Ribosomal Subunit: Macrolides (Azithromycin, Erythromycin, Clarithromycin), Clindamycin, and Chloramphenicol
- 30S Ribosomal Subunit: Aminoglycosides (Tobramycin, Amikacin, Gentamicin) and Tetracycline (Doxycycline, Tetracycline)
Bacterial Coverage
- Gram Positive Coverage
- Examples: Beta-Lactams (Penicillin, Cephalosporin, Carbapenem, Monobactam) and Vancomycin
- Gram Negative Coverage
- Examples: Beta-Lactams (Penicillin, Cephalosporin, Carbapenem, Monobactam) and Fosfomycin
- Anaerobic Coverage
- Examples: Metronidazole and Nitrofurantoin
- Atypical Coverage
- Examples: Azithromycin and Rifampin (used in tuberculosis)
Empiric Antibiotics for Common Infections
- Pulmonary
- Examples: Cephalosporin and Macrolides
- Gastrointestinal
- Examples: Cephalosporin and Fluoroquinolones
- Skin and Soft Tissues
- Examples: Cephalosporin and Beta-Lactams
- Urinary Tract
- Examples: Fluoroquinolones and Cephalosporin
- Bone and Joint
- Examples: Fluoroquinolones and Cephalosporin
- CNS
- Examples: Beta-Lactams and Cephalosporin
- Bloodstream
- Examples: Beta-Lactams and Cephalosporin### Bacterial Coverage
Gram Positive Coverage
- Methicillin Sensitive Staphylococcus aureus (MSSA):
- Treated with anti-staphylococcal penicillin (nafcillin, oxacillin, dicloxacillin)
- 1st generation cephalosporins (cephalexin, cefazolin)
- Fluoroquinolones
- Methicillin Resistant Staphylococcus aureus (MRSA):
- Treated with 5th generation cephalosporin (ceftaroline)
- Vancomycin
- Trimethoprim-sulfamethoxazole
- Clindamycin
- Linezolid
- Doxycycline
- Daptomycin
- Streptococcus pneumoniae:
- Treated with penicillin
- Aminopenicillins
- 3rd generation cephalosporins (ceftriaxone)
- Fluoroquinolones (moxifloxacin, levofloxacin)
- Macrolides
- Clindamycin
- Streptococcus (Group A & B):
- Treated with anti-staphylococcal penicillin (nafcillin, oxacillin, dicloxacillin)
- 1st generation cephalosporins (cephalexin, cefazolin)
Gram Negative Coverage
- HENS-PEcK organisms:
- Hemophilus influenzae
- Enterobacter
- Neisseria gonorrhoeae and meningitidis
- Serratia
- Proteus
- Escherichia coli
- Klebsiella
- Treated with aminopenicillins (ampicillin)
- Anti-pseudomonal penicillin (piperacillin-tazobactam)
- 1st generation cephalosporins (cephalexin, cefazolin)
- 2nd, 3rd, 4th generation cephalosporins
- Carbapenems (doripenem, imipenem, meropenem, ertapenem)
- Monobactams
- Fluoroquinolones
- Aminoglycosides
- Extended spectrum beta lactamase bacteria (ESBL):
- Enterobacteriaceae
- Treated with carbapenems (doripenem, imipenem, meropenem, ertapenem)
- 3rd generation cephalosporin + beta lactamase inhibitor (ceftazidime+avibactam)
Anaerobic Coverage
- CBPFA organisms:
- Clostridium
- Bacteroides
- Peptostreptococcus
- Fusobacterium
- Actinomyces
- Treated with clindamycin
- Metronidazole
- Carbapenems
- Anti-pseudomonal penicillin (piperacillin-tazobactam)
- Fluoroquinolones
- MCL organisms:
- Mycoplasma
- Chlamydia
- Legionella
- Treated with fluoroquinolones
- Macrolides
- Chloramphenicol
- Doxycycline
Empiric Antibiotics for Common Infections
-
Pulmonary:
- Community-Acquired Pneumonia (CAP):
- Fluoroquinolones (respiratory)
- Beta-lactam (ceftriaxone) + macrolide or doxycycline
- Hospital-Acquired Pneumonia (HAP):
- Vancomycin
- Antipseudomonal penicillin (piperacillin-tazobactam)
- Ceftazidime, cefepime, or an aminoglycoside
- Community-Acquired Pneumonia (CAP):
-
Gastrointestinal:
- Gram-Negatives and Anaerobes:
- Carbapenems
- Antipseudomonal penicillins (piperacillin-tazobactam)
- Metronidazole + fluoroquinolone (ciprofloxacin)
- Metronidazole + ceftriaxone
- Metronidazole + cefepime
- Gram-Negatives and Anaerobes:
-
Skin and Soft Tissues:
- MSSA + Strep A:
- PO: dicloxacillin or cephalexin
- IV: nafcillin or oxacillin or cefazolin
- MRSA + Strep A:
- PO: TMP-SMX, doxycycline, or clindamycin
- IV: vancomycin
- MSSA + Strep A:
-
Urinary Tract:
- Pyelonephritis:
- Ceftriaxone
- Fluoroquinolone (ciprofloxacin)
- Aminopenicillin (ampicillin)
- Complicated UTI:
- Vancomycin
- Antipseudomonal penicillin (piperacillin-tazobactam)
- Ceftazidime, cefepime, or an aminoglycoside
- Pyelonephritis:
-
Bone and Joint:
- Septic arthritis, osteomyelitis:
- Vancomycin
- Ceftriaxone
- Cefepime, ceftazidime, or an aminoglycoside
- Septic arthritis, osteomyelitis:
-
CNS:
- Community-Acquired Meningitis (CAM):
- Vancomycin
- 3rd generation cephalosporin (ceftriaxone)### Empiric Antibiotics for Meningitis
- Community-Acquired Meningitis (CAM):
-
Ceftriaxone: good CNS penetration, covers H. catarrhalis and N. meningitidis
-
Ampicillin: consider for Listeria, especially in older patients (> 60 y/o), immunocompromised patients, and babies
-
Hospital-Acquired Meningitis (HAM): consider MRSA and Pseudomonas, use Vancomycin and Cefepime respectively
Empiric Antibiotics for Bloodstream Infections
- Central Line Bloodstream Infection (CLABSI): consider MRSA, use Vancomycin and +/- Pip-Tazo
- Sepsis: consider Vancomycin and Pip-Tazo for Gram-positives and Gram-negatives respectively
Antibiotics Pharmacology
- Adverse effects:
- Neurotoxicity: seizures, myoclonus, encephalopathy, serotonin syndrome
- Pancytopenia: hemolytic anemia, especially with beta-lactams
- Teratogenicity: avoid during pregnancy, especially with TMP-SMX
- Hyperkalemia: TMP-SMX
Mechanisms of Antibiotic Resistance
- Reduced permeability:
- Vancomycin
- Aminoglycosides
- Tetracyclines
- Beta-lactams
- Increased efflux:
- Fluoroquinolones
- Aminoglycosides
- Tetracyclines
- Macrolides
- Decreased target binding:
- Fluoroquinolones
- Aminoglycosides
- Tetracyclines
- Beta-lactams
- Macrolides
- Linezolid
- Trimethoprim-Sulfamethoxazole
- Increased inactivating enzymes:
- Beta-lactams: beta-lactamase, carbapenemase
- Aminoglycosides: phosphorylation, acetylation, methylation reactions
- Macrolides
Transmission of Antibiotic Resistance
- Bacteria can pass on resistance mechanisms to other bacteria through:
- Reduced permeability
- Increased efflux
- Decreased target binding
- Increased inactivating enzymes
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