Podcast
Questions and Answers
What is the mechanism of action of carbapenems?
What is the mechanism of action of carbapenems?
Which adverse effect is associated with imipenem?
Which adverse effect is associated with imipenem?
Which of the following antibiotics is resistant to beta-lactamases?
Which of the following antibiotics is resistant to beta-lactamases?
What is a common adverse effect of cefoperazone?
What is a common adverse effect of cefoperazone?
Signup and view all the answers
Which cephalosporin interaction increases the risk of nephrotoxicity?
Which cephalosporin interaction increases the risk of nephrotoxicity?
Signup and view all the answers
What is the primary function of B-lactamase inhibitors?
What is the primary function of B-lactamase inhibitors?
Signup and view all the answers
What is the primary mechanism of action of penicillins?
What is the primary mechanism of action of penicillins?
Signup and view all the answers
What adverse effect is particularly associated with methicillin?
What adverse effect is particularly associated with methicillin?
Signup and view all the answers
What is a common interaction between penicillins and oral contraceptives?
What is a common interaction between penicillins and oral contraceptives?
Signup and view all the answers
Which generation of cephalosporins is known for its increased resistance to beta-lactamases?
Which generation of cephalosporins is known for its increased resistance to beta-lactamases?
Signup and view all the answers
What is a characteristic of third generation cephalosporins?
What is a characteristic of third generation cephalosporins?
Signup and view all the answers
Study Notes
Beta Lactamase Inhibitors
- Powerful B-lactamase inhibitors are used to protect penicillins from inactivation by B-lactamases, making them effective against bacteria that produce these enzymes, such as Staphylococcus aureus, Haemophilus influenzae, Escherichia coli, Proteus, and Pseudomonas aeruginosa.
- Common examples include Clavulanic acid and Sulbactam.
- Clavulanic acid combined with amoxicillin is known as Augmentin (oral).
- Sulbactam combined with ampicillin is called Unasyn (oral, intramuscular, and intravenous).
Penicillin Uses
- Penicillin is a vital antibiotic used to treat various infections.
- Staphylococcal infections: It is used with penicillinase-resistant penicillin like nafcillin and oxacillin or with a beta-lactamase inhibitor.
- Streptococcal infections: Effective against pharyngitis, pneumonia, arthritis, meningitis, endocarditis, puerperal fever, and wound sepsis.
- Pneumococcal infections: Treats pneumonia and meningitis.
- Salmonella infections: High doses of ampicillin are effective against typhoid and paratyphoid fever.
- Shigella dysentery: Amoxicillin or ampicillin are used in treatment.
- Pseudomonas infections: Requires the use of antipseudomonal penicillins.
- Meningococcal infections: Penicillin G is the preferred drug.
- Gonococcal infections: Also treats anthrax and syphilis.
- Diphtheria: Penicillin is used to eliminate diphtheria bacilli from the pharynx; however, specific antitoxin is the most important treatment.
- H. influenzae infections: Ampicillin is the preferred drug.
Penicillin Uses for Prophylaxis
- Streptococcal infections: Penicillin G or V is used in outbreaks to prevent the spread of streptococcal disease in closed populations.
- Recurrences of Rheumatic fever: Benzathine penicillin is administered once a month intramuscularly to prevent recurrence.
- Gonorrhea and syphilis: Used for sexual contacts of patients with gonorrhea or syphilis.
- Prevention of gonorrheal ophthalmia in neonates: Benzylpenicillin is instilled into the conjunctiva.
- Surgical procedures in patients with valvular heart disease: Procaine penicillin is used to prevent subacute bacterial endocarditis.
Penicillin Adverse Effects
- Allergic reactions: Common side effects include itching, rash, and anaphylaxis.
- Pain and sterile inflammatory reactions: Can occur at the site of intramuscular injections.
- Jarisch-Herxheimer reaction in late syphilis: Febrile reactions can occur after the first penicillin injections due to the rapid destruction of treponemas in syphilitic lesions.
- Diarrhea: Disrupts the normal balance of intestinal microorganisms.
- Positive Coombs' reactions: Rare but possible with parenteral high doses, hemolysis is uncommon.
- Diarrhea especially with cefoperazone: This is due to the drug's greater biliary excretion.
- Local irritation: Severe pain after IM injection and thrombophlebitis after IV injection.
- Cross-resistance: This can occur with other penicillins.
Cephalosporins:
- Beta-lactam antibiotics derived from 7-aminocephalosporanic acid.
- Mechanism of action: Similar to penicillins, they are bactericidal and inhibit cell wall synthesis.
Classification of Cephalosporins
- First generation: Effective against most gram-positive organisms and some gram-negative organisms. They do not penetrate the cerebrospinal fluid, have a half-life of 2 hours, and are inactivated by B-lactamases. Examples include cephradine and cefazolin.
- Second generation: Have an extended spectrum compared to the first generation, effective against H. influenzae, Proteus, and Enterobacter. They do not penetrate the CSF, have a half-life of 4 hours, and are relatively resistant to B-lactamases. Examples include cefoxitin and cefaclor.
- Third generation: Have reduced activity against gram-positive organisms, but enhanced activity against gram-negative organisms. Moderately active against anaerobes. Some members, like cefoperazone and ceftazidime, are active against P. aeruginosa. Most penetrate the CSF, have a half-life of 8 hours, and are resistant to destruction by B-lactamase. Examples include ceftazidime and cefoperazone.
- Fourth generation: Comparable to third-generation but more resistant to some B-lactamases. Examples include cefepime.
- Fifth generation: Broad-spectrum prodrug of an active metabolite, ceftaroline. Requires dose adjustment in renal impairment. Example: Ceftaroline.
Carbapenems
- Mechanism of action is similar to penicillins.
- Resistant to B-lactamases.
-
Imipenem:
- Antibacterial spectrum encompasses most gram-negative aerobic, gram-positive aerobic bacteria, and anaerobic microorganisms (widest spectrum).
- It is metabolized to a nephrotoxic metabolite in the kidney by dehydropeptidase I, so it is combined with cilastatin (an inhibitor of dehydropeptidase I).
- Side effects include gastrointestinal issues (nausea, vomiting, diarrhea), blood disorders (eosinophilia, neutropenia), and seizures at high doses.
-
Meropenem:
- Similar to imipenem but is not inactivated by dehydropeptidase I.
Monobactams
- Mechanism of action similar to penicillins.
- Resistant to B-lactamases.
- Only effective against aerobic Gram-negative bacteria (such as Neisseria and Pseudomonas).
- No cross-allergy with other B-lactams.
- The currently available monobactam is aztreonam.
Nephritis and Penicillins
- All penicillins, particularly methicillin, can cause acute interstitial nephritis.
Neurotoxicity of Penicillins
- Penicillins are irritating to neuronal tissue, and high blood levels or intrathecal injections can trigger seizures. Epileptic patients are at higher risk.
Cation Toxicity of Penicillins
- Hyperkalemia can occur with rapid intravenous injections of potassium penicillin G; sodium overload can occur with carbenicillin and ticarcillin.
Other Penicillin Side Effects
- Agranulocytosis: Can occur with methicillin and cloxacillin.
- Hepatitis: Can occur with oxacillin.
Drug interactions of penicillins
- Ampicillin and oral contraceptives: Ampicillin may reduce the effectiveness of oral contraceptives.
- Penicillins and probenecid: Probenecid blocks penicillin excretion, leading to higher serum levels.
- Penicillins and aminoglycosides: These drug combinations have synergistic antibacterial effects.
Drug interactions of cephalosporins
- Cephalosporins can increase the risk of nephrotoxicity when combined with aminoglycosides, probenecid, frusemide, ethacrynic acid, and vancomycin.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
This quiz covers important aspects of beta-lactamase inhibitors and their role in protecting penicillins from bacterial inactivation. Learn about the common types of inhibitors, specific uses of penicillin against various infections, and the combinations that enhance their effectiveness. Test your knowledge on this crucial topic in antibiotics.
