Treatment of experimental Salmonella typhimurium infection in mice with lomefloxacin

Fluoroquinolones in animal health

The fluoroquinolones are a series of synthetic antibacterial agents that are undergoing extensive investigation for both human and veterinary use in the treatment of a variety of bacterial infections. These agents work through the inhibition of DNA gyrase, interfering with the supercoiling of bacterial chromosomal material. As a result, these agents are rapidly bactericidal primarily against gram-negative bacteria, mycoplasma, and some gram-positive bacteria, with most having little to no activity against group D streptococci and obligate anaerobic bacteria. Resistance develops slowly and is almost always chromosomal and not plasmid-mediated. However, development of resistance to the fluoroquinolones and transfer of that resistance among animal and human pathogens have become a hotly debated issue among microbiologists. The fluoroquinolones are a current antimicrobial class whose use in veterinary medicine is being scrutinized. From a pharmacokinetic perspective, these agents are variably but well absorbed from the gastrointestinal tract and almost completely absorbed from parenteral injection sites, and they are well distributed to various tissues in the body. The fluoroquinolones are metabolized and renally excreted, with many of them having approximately equal excretion by the hepatic and the renal excretory systems. The primary toxicity observed at therapeutic doses involves the gastrointestinal system and phototoxicity, although at higher doses central nervous system toxicity and ocular cataracts are observed. Administration to immature animals may result in erosive arthropathies at weight-bearing joints, and administration of high doses to pregnant animals results in maternotoxicity and occasionally embryonic death. The fluoroquinolones are approved for indications such as urinary tract infections and soft tissue infections in dogs and cats and colibacillosis in poultry. Approval for bovine respiratory disease in the United States is being sought. Other indications for which the fluoroquinolones have been used in animal health include deep-seated infections, prostatitis, and other bacterial infections resistant to standard antimicrobial therapy.

Effects of rufloxacin in Salmonella typhimurium infection in mice

This study was undertaken to investigate the efficacy of rufloxacin, a new quinolone which is interesting due to its pharmacokinetics characterized by a long plasma half-life, in the treatment of systemic salmonella infections in the mouse typhoid model. Innately susceptible BALB/c and resistant CBA mice were used to investigate the efficacy of rufloxacin in controlling systemic salmonella infections when given for brief or prolonged periods. The present study shows that rufloxacin is not only very effective on both mouse strains, but can completely eradicate the salmonellae from livers and spleens when given early in the infection of CBA resistant mice.

Lomefloxacin. A review of its antibacterial activity, pharmacokinetic properties and therapeutic use

The antibacterial efficacy of oral lomefloxacin has been investigated in a wide variety of infections, including respiratory and uncomplicated and complicated urinary tract infections, obstetric, gynaecological, joint, skin, oral, ear, nose, throat and eye infections. It has also been used as an otic solution in patients with otitis media and as an ophthalmic solution in the treatment of eye infections. In clinical trials its efficacy is equivalent to that of other quinolones and it is at least as effective as other antibacterial drugs ordinarily used in these infections. Lomefloxacin offers certain advantages compared with other quinolone antibacterial drugs in that it may be conveniently administered once daily and theophylline dosage adjustment does not appear to be necessary in patients receiving this bronchodilator concomitantly. Thus, orally administered lomefloxacin should prove a useful broad spectrum antibacterial drug for a wide variety of clinical infections.

Newly documented antimicrobial activity of quinolones

The improved antimicrobial activity of newer fluoroquinolones and novel applications recently found for the drugs already marketed are reviewed. Several new compounds are more active against gram-positive bacteria than the presently marketed fluoroquinolones. WIN 57273, the most potent compound in vitro on a weight basis, is 16 to 128 times more active than ciprofloxacin against various staphylococci, streptococci, Enterococcus spp., Corynebacterium spp., Listeria monocytogenes and Bacillus spp. BMY 40062, PD 117558, PD 127391, sparfloxacin, temafloxacin and tosufloxacin also show enhanced in vitro efficacy against these species. These drugs also possess increased activity against various anaerobes, notably Clostridium perfringens, Clostridium difficile and the Bacteroides fragilis group. Mycobacterium tuberculosis, rapidly growing mycobacteria other than Mycobacterium chelonae, and Mycobacterium leprae are often susceptible to quinolones displaying bactericidal activity which is potentially useful for curing difficult-to-treat mycobacteriosis. In addition, a number of new products, notably those containing a cyclopropyl group, are more active than reference fluoroquinolones against Mycobacterium leprae. Sparfloxacin, BMY 40062 and WIN 57273 compare favorably with older fluoroquinolones in the killing of intracellular Legionella spp., and several of the newer compounds have greater antichlamydial potency. Improved antibacterial activity has also been found against Mycoplasma hominis, Ureaplasma urealyticum, Acinetobacter spp. and Pseudomonas maltophilia. By contrast, the newer quinolones have similar or less activity against Pseudomonas aeruginosa and Enterobacteriaceae. Recently, pefloxacin, ofloxacin and ciprofloxacin were found to be active against protozoa, including Plasmodium spp., Trypanosoma cruzi and Leishmania donovani, but not against Toxoplasma gondii. In the near future, more specific research testing unusual pathogens may lead to the identification of quinolones with more selective activity.