Origin and group representatives
This pharmacological group is based on natural compounds—pristinamycins, which are produced by the microorganism Streptomyces pristinaespiralis. Modern drugs are semisynthetic.
The group includes two agents belonging to different subclasses:
- Quinupristin—belongs to group B streptogramins.
- Dalfopristin—belongs to group A streptogramins.
An important feature of pharmacotherapy is that these components are never prescribed separately. They are used exclusively as a single fixed combination.
Mechanism of antimicrobial action
The drug targetedly attacks the protein synthesis apparatus of the microbial cell at the ribosomal level.
Main molecular effects:
- Binding to the 50S ribosomal subunit.
- Blocking the peptidyl transferase enzyme.
- Disruption of the translocation process (transfer of the peptide from the A-site to the P-site).
- Prevention of the elongation of the peptide chain outwards.
As a result of this double blow, protein synthesis in the bacterial cell is completely halted.
Spectrum of activity and effect type
The nature of the effect on microorganisms depends on their species:
- Bactericidal type—manifests against most gram-positive microorganisms, completely destroying them.
- Bacteriostatic type—observed specifically when acting on strains of Enterococcus faecium, stopping their growth and reproduction.
The spectrum of antimicrobial activity covers gram-positive flora, as well as pathogens of atypical pneumonia, including chlamydia, mycoplasma, and legionella.
Clinical use and side effects
The combination is used to treat severe, life-threatening conditions.
Main indications:
- Infections caused by vancomycin-resistant strains of Enterococcus faecium.
- Complicated skin and soft tissue infection processes caused by staphylococci (including methicillin-resistant MRSA) and streptococci.
Possible adverse reactions:
- Local manifestations: inflammation and pain at the injection site (phlebitis).
- Gastrointestinal tract and liver: dyspeptic disorders, increased blood bilirubin levels.
- Musculoskeletal system: joint pain (arthralgia) and muscle pain (myalgia).
- Nervous system: headache.
Briefly: answers to topical questions
What is the route of administration and dosing regimen of the drug?
The combined drug quinupristin/dalfopristin is administered intravenously every 8–12 hours.
- Route of administration—intravenous administration.
- Dosing regimen—every 8–12 hours.
Class and exam questions
Why are the combination components not used separately?
Quinupristin and dalfopristin act synergistically, blocking protein synthesis at different stages of 50S ribosomal subunit function, and only co-administration provides the necessary clinical effect.
What is the type of action of the drug on Enterococcus faecium?
Against this specific pathogen, the combination exhibits a bacteriostatic type of action, stopping its reproduction.
For which skin and soft tissue infections are streptogramins prescribed?
The drug is used for complicated and life-threatening infections caused by streptococci and staphylococci, including resistant MRSA strains.
What else to study on this topic
- Structural differences between group A and B streptogramins
- Pharmacokinetics of quinupristin and dalfopristin upon intravenous administration
- Mechanisms of bacterial resistance development to streptogramins
- Features of drug-drug interactions via the cytochrome P450 system
- Patient management tactics in case of arthralgia and myalgia during therapy
Master the entire topic in the «Pharmacology» course
This is a summary. The course covers everything tested in classes and exams.
- Complete study guide on "Streptogramins" and another 5,304 pages of the subject
- Assignments and quizzes after every topic — just like in a colloquium
- AI tutor answers questions on the topic anytime
- 116 video lessons on the subject
Other topics in the section "Antibacterial Chemotherapeutic Agents"
Free video lessons: pharmacologyShort lessons with study notes — no registration required.
Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.