Author: Brian Holtry

Quinupristin and dalfopristin is a combination of 2 semisynthetic streptogramin (synergistin) antibiotics that act synergistically against susceptible gram-positive bacteria.

Quinupristin and dalfopristin is administered by IV infusion over 60 minutes. Quinupristin and dalfopristin powder for injection must be reconstituted and diluted prior to administration. The manufacturer states that only 5% dextrose injection or sterile water for injection should be used to reconstitute the powder, and further dilution should be with 5% dextrose. Strict aseptic technique must be observed since the drug contains no preservative.

Systemic use of polymyxin B has, in most cases, been replaced by more effective and less toxic antibiotics for infections caused by susceptible organisms. However, polymyxin B may be useful in infections caused by organisms resistant to these drugs.

Colistimethate sodium is used in the treatment of acute or chronic infections caused by susceptible strains of certain gram-negative bacteria (e.g., Enterobacter aerogenes, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa).

Lincomycin should be not used for the treatment of minor bacterial infections or for nonbacterial infections. Because of poor CNS penetration, lincomycin should not be used in the treatment of meningitis.

Adverse GI effects frequently occur with oral, IM, or IV lincomycin and may be severe enough to necessitate discontinuance of the drug. Adverse GI effects of lincomycin include nausea, vomiting, diarrhea, abdominal pain, tenesmus, glossitis, stomatitis, and pruritus ani.

The drug also is active in vitro against Arcanobacterium haemolyticum (formerly Corynebacterium haemolyticum). Clindamycin is active against some anaerobic and microaerophilic gram-negative and gram-positive organisms including Actinomyces, Bacteroides, Eubacterium, Fusobacterium, Propionibacterium, microaerophilic streptococci, Peptococcus, Peptostreptococcus, and Veillonella. Clindamycin is active in vitro against Prevotella and Porphyromonas (both formerly classified as Bacteroides); Mobiluncus (motile, anaerobic, curved rods) also are inhibited in vitro by the drug. Clostridium perfringens, C. tetani, Corynebacterium diphtheriae, and Mycoplasma are also inhibited by clindamycin.

Adverse GI effects frequently occur with oral, IM, or IV clindamycin and may be severe enough to necessitate discontinuance of the drug. Adverse GI effects of clindamycin include nausea, vomiting, diarrhea, abdominal pain, and tenesmus.