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What is the primary mechanism of action of aminoglycosides?
Which of the following is a common adverse effect of aminoglycosides?
What is the purpose of monitoring serum levels of aminoglycosides?
What is the primary mechanism of action of quinolones?
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Which of the following is a common interaction with quinolones?
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What is the black box warning associated with quinolones?
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What is the primary site of infection for Mycobacterium tuberculosis?
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Which of the following antibiotics is used to treat protozoal infections?
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Which of the following organisms is resistant to all beta-lactam antibiotics and aztreonam?
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What is the primary concern regarding MRSA infections?
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What is the term for the nodular accumulations of inflammatory cells that are delimited by clear boundaries and have a cheesy or caseated consistency in the lungs?
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Which of the following aminoglycosides is an exception to the poor oral absorption rule?
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What is the term for the chronic form of tuberculosis?
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Which antibiotic is indicated for the treatment of antibiotic-induced colitis and staphylococcal enterocolitis?
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What is the primary mechanism of action of aminoglycosides?
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What is the primary indication for the use of aminoglycosides?
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What is the primary drug used to treat tuberculosis?
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What is the consequence of the use of carbapenems to treat ESBL-producing organisms?
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What is the primary reason for the resurgence of tuberculosis cases in the United States in 1992?
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What is the main concern regarding multidrug-resistant tuberculosis (MDR-TB)?
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What is the purpose of performing an acid-fast bacillus smear test on sputum?
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Why is Bacille Calmette-Guérin (BCG) vaccine not used in the United States?
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What is the main goal of antitubercular drug therapy?
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Why is it important to perform drug-susceptibility testing on the first Mycobacterium spp. isolated from a patient specimen?
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Why is patient education critical in tuberculosis treatment?
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What should patients be instructed to avoid while taking rifampin?
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Why may pyridoxine be needed in patients taking INH therapy?
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What should be monitored in patients taking tuberculosis medications?
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What is a potential consequence of rifampin therapy?
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Why should patients taking rifampin use an alternative form of birth control?
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What is the importance of taking tuberculosis medications at the same time every day?
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Why should patients be instructed to take care of themselves during tuberculosis treatment?
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What should be monitored to confirm clinical findings in tuberculosis treatment?
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What should be reported to the prescriber immediately in patients taking tuberculosis medications?
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What is the primary mechanism of action of bedaquiline?
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Why is it important to monitor liver function tests when administering isoniazid?
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What is a common interaction between rifampin and oral contraceptives?
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What is a common adverse effect of rifampin?
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Why is it important to educate clients taking rifampin about oral contraceptives?
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What is a common contraindication for the use of isoniazid?
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Study Notes
Multidrug-Resistant Organisms
- Organisms that are resistant to one or more classes of antimicrobial drugs
- Examples:
- Methicillin-resistant Staphylococcus aureus (MRSA)
- Vancomycin-resistant Enterococcus (VRE)
- Organisms producing extended-spectrum beta-lactamases (ESBLs)
- Carbapenem-resistant Enterobacteriaceae (CRO)
MRSA
- Threat of MRSA becoming resistant to all antibiotics currently available
- No longer seen just in hospitals; it has spread to the community setting
- Approximately 50% of staphylococcal infections contracted in the community involve MRSA
ESBL
- Organisms that produce ESBL are resistant to all beta-lactam antibiotics and aztreonam
- Can be treated only with carbapenems or sometimes quinolones
- Use of carbapenems: resistance occurred; production of carbapenemase, which renders all carbapenems ineffective
- Other treatment options: tigecycline and colistimethate
Aminoglycosides
- Natural and semisynthetic
- Produced from Streptomyces spp.
- Poor oral absorption; no oral forms (exception: neomycin)
- Very potent antibiotics with serious toxicities
- Bactericidal; prevent protein synthesis
- Kill mostly gram-negative bacteria; some gram-positive bacteria
- Examples:
- Gentamicin
- Neomycin (Neo-Fradin)
- Tobramycin (TOBI)
- Amikacin
Quinolones
- Also called fluoroquinolones
- Excellent oral absorption
- Absorption reduced by antacids
- Effective against gram-negative organisms and some gram-positive organisms
- Examples:
- Ciprofloxacin (Cipro)
- Norfloxacin (Noroxin)
- Levofloxacin (Levaquin)
- Moxifloxacin (Avelox)
- Gemifloxacin (Factive)
- Delafloxacin (Baxdela)
Mechanism of Action of Quinolones
- Bactericidal
- Alter DNA of bacteria, causing death
- Do not affect human DNA
- Used to treat S.aureus, Serratia marcescens, and Mycobacterium fortuitum
Adverse Effects of Quinolones
- CNS: headache, dizziness, insomnia, depression, restlessness, convulsions
- GI: nausea, vomiting, diarrhea, constipation, thrush, increased liver function study results
- Cardiac: prolonged QT interval
- Integumentary: rash, pruritus, urticaria, flushing
- Other: ruptured tendons, tendonitis, fever, chills, blurred vision, tinnitus
Tuberculosis (TB)
- Caused by Mycobacterium tuberculosis
- Antitubercular drugs treat all forms of Mycobacterium (MTB)
- TB is most commonly characterized by granulomas in the lungs: nodular accumulations of inflammatory cells
- Infections:
- Common infection sites: lung, brain, bone, liver, kidney, genitourinary tract
- Aerobic bacillus
- Passed from infected humans, cows (bovine), and birds (avian)
- Tubercle bacilli are conveyed by droplets
Antitubercular Drugs
- First-line drugs:
- INH
- Rifapentine
- Ethambutol
- Rifabutin
- Pyrazinamide (PZA)
- Rifampin
- Streptomycin
- Second-line drugs:
- Bedaquiline
- Capreomycin
- Cycloserine
- Levofloxacin
- Ethionamide
- Ofloxacin
- Kanamycin
- Para-aminosalicylic acid (PAS)
Diagnosis of TB
- Step 1: Tuberculin skin test (Mantoux test)
- Step 2: If skin test results are positive, then chest x-ray
- Step 3: If chest x-ray shows signs of tuberculosis, then culture of sputum or stomach secretions
Multidrug-Resistant Tuberculosis (MDR-TB)
- TB infects one-third of the world's population
- MDR-TB that is resistant to both isoniazid (INH) and rifampin
- Extensively drug-resistant tuberculosis (XDR-TB): relatively rare type of MDR-TB, resistant to almost all drugs used to treat TB
Bedaquiline (Sirturo)
- First drug approved in over 40 years for treatment of multidrug-resistant TB
- Inhibits mycobacterial ATP synthase
- Adverse effects: headache, chest pain, nausea, and QT prolongation
- Interactions: alcohol, mifepristone, other drugs with high risk for causing QT prolongation
Isoniazid (INH)
- Inhibits growth of mycobacteria by preventing synthesis of mycolic acid in the cell wall
- Indications: for active and latent tuberculosis
- Metabolized in the liver through acetylation—watch for "slow acetylators"
- Used alone or in combination with other drugs
- Contraindicated with liver disease; monitor ALT, AST
Adverse Effects of Isoniazid (INH)
- Peripheral neuropathy: tingling, numbness, binding, and pain resulting from deficiency of pyridoxine (vitamin B6)
- Hepatotoxicity: anorexia, malaise, fatigue, nausea, and yellowish discoloration of skin and eyes
- Monitor liver function tests; if elevated, may result in need to discontinue medication and avoid alcohol consumption
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Description
Learn about multidrug-resistant organisms such as MRSA, their characteristics, and the threats they pose. Understand the implications of antibiotic resistance in various settings.
