Origin and Drug Representatives
This pharmacological group is based on natural compounds—pristinamycins—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 targets the microbial protein synthesis apparatus at the ribosomal level.
Key molecular effects:
- Binding to the 50S ribosomal subunit.
- Inhibition of the peptidyl transferase enzyme.
- Disruption of translocation (transfer of the peptide from the A-site to the P-site).
- Prevention of the exit of the elongating peptide chain.
As a result of this dual strike, protein synthesis in the bacterial cell is completely halted.
Spectrum of Activity and Type of Effect
The nature of the effect on microorganisms depends on the species:
- Bactericidal effect — manifests against most gram-positive microorganisms, completely eradicating them.
- Bacteriostatic effect — observed specifically against Enterococcus faecium strains, arresting their growth and reproduction.
The spectrum of antimicrobial activity covers gram-positive flora as well as atypical pneumonia pathogens, including chlamydiae, mycoplasmas, and legionellae.
Clinical Application 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 infections caused by staphylococci (including methicillin-resistant Staphylococcus aureus [MRSA]) and streptococci.
Potential adverse reactions:
- Local manifestations: inflammation and pain at the injection site (phlebitis).
- Gastrointestinal and hepatic: dyspeptic disorders, elevated blood bilirubin levels.
- Musculoskeletal system: joint pain (arthralgia) and muscle pain (myalgia).
- Nervous system: headache.