Tigecycline: a new glycylcycline antimicrobial.

Tigecycline is a new glycyclcycline antimicrobial recently approved for use in the USA, Europe and elsewhere. While related to the tetracyclines, tigecycline overcomes many of the mechanisms responsible for resistance to this class. It demonstrates favourable in vitro potency against a variety of aerobic and anaerobic Gram-positive and Gram-negative pathogens, including those frequently demonstrating resistance to multiple classes of antimicrobials. This includes methicillin-resistant Staphylococcus aureus, penicillin-resistant S. pneumoniae, vancomycin-resistant enterococci, Acinetobacter baumannii, beta-lactamase producing strains of Haemophilis influenzae and Moraxella catarrhalis, and extended-spectrum beta-lactamase producing strains of Escherichia coli and Klebsiella pneumoniae. In contrast, minimum inhibitory concentrations for Pseudomonas and Proteus spp. are markedly elevated. Tigecycline is administered parenterally twice daily. Randomised, controlled trials have demonstrated that tigecycline is non-inferior to the comparators for the treatment of complicated skin and skin structure infections, as well as complicated intra-abdominal infections. The most frequent and problematic side effect associated with its administration to date has been nausea and/or vomiting.

Proposed mechanisms and preventative options of Jarisch-Herxheimer reactions.

OBJECTIVE: To review the aetiologies and preventative methods associated with Jarisch-Herxheimer reactions (JHR). DATA SOURCES: Ovid Medline (1966-June Week 1 2004) was utilized to assess biomedical literature; a review of the bibliographies of articles was also performed. DATA SYNTHESIS: JHR often occurs with the treatment of spirochete infections. However, the mechanism by which the reaction takes place is not clearly defined. CONCLUSION: Studies suggest with conflicting evidence that the JHR is caused by release of endotoxin-like material from the spirochete as well as cytokine elevation in the body. It appears the type of drug and the rate of spirochete clearance from the body have little effect on the incidence of the reaction. Many pretreatment options have been explored with limited efficacy with the exception of anti-tumour necrosis factor antibodies.