Antimycobacterial activities of novel levofloxacin analogues

Recent advances in the design and synthesis of heterocycles as anti-tubercular agents

Due to the unusual structure and chemical composition of the mycobacterial cell wall, effective tuberculosis (TB) treatment is difficult, making many antibiotics ineffective and hindering the entry of drugs. With approximately 33% of infection, TB is still the second most deadly infectious disease worldwide. The reasons for this are drug-resistant TB (multidrug resistant and extensively drug resistant), persistent infection (latent TB) and synergism of TB with HIV; furthermore no new chemical entity has emerged in last 40 years. New data available from the recently sequenced genome of the mycobacterium and the application of methods of modern drug design promise much for the fight against this disease. In this review, we present an introduction to TB, followed by an overview of new heterocyclic anti-tubercular moieties published during the last decade.

Importance of the efflux pump systems in the resistance of Mycobacterium tuberculosis to fluoroquinolones and linezolid

OBJECTIVE

Our aim was to study the influence of efflux pump systems in the resistance of Mycobacterium tuberculosis to fluoroquinolones and linezolid.

METHODS

We studied the mutations in gyrA and gyrB genes and the influence of efflux pump systems with 2 inhibitors (reserpine and MC 207.110).

RESULTS

The effect of the active efflux system on the decrease in sensitivity to ciprofloxacin, moxifloxacin, levofloxacin, ofloxacin, gatifloxacin and linezolid was studied by investigating the variation in the in vitro activity of these compounds when assayed in association with reserpine and MC 207.110. These inhibitors exhibit activity both in strains that are resistant and in strains that are susceptible to these antibiotics. However, they are seen to be most active in resistant strains, since the minimum inhibitory concentration of the antibiotics studied in these strains was reduced between 2- and 6-fold.

CONCLUSIONS

Therefore, these mechanisms are involved in the resistance to both compounds. It would be of interest to carry out further studies to determine to what extent these active efflux systems influence resistance to the different groups of drugs used in the treatment of tuberculosis, with a view to the possibility of using the inhibitors of these systems in future therapeutic applications.

Pharmacokinetics and pharmacodynamics of gatifloxacin against Streptococcus pneumoniae and Staphylococcus aureus in a granulocyte-rich exudate

The pharmacokinetics of gatifloxacin were assessed in serum and in skin blister fluid (SBF), as was the pharmacodynamic activity in SBF. Five hours after a single dose of gatifloxacin, SBF killed 2.5 logs of Streptococcus pneumoniae and 1.5 log of Staphylococcus aureus during a 2-h incubation ex vivo.