In vitro susceptibility of Mycobacterium tuberculosis to ofloxacin and ciprofloxacin in combination with rifampin and isoniazid

The in vitro susceptibility of Mycobacterium tuberculosis to new quinolones, ofloxacin and ciprofloxacin, alone and in combination with rifampin or isoniazid, was studied by the agar dilution method. At a concentration of 1 mg/l or lower of ofloxacin and ciprofloxacin, 90% of the strains were inhibited. A synergistic effect with rifampin and with isoniazid was demonstrated.

Bactericidal effect of ofloxacin alone and combined with fosfomycin or vancomycin against Staphylococcus aureus in vitro and in sera from volunteers

The bactericidal activity of ofloxacin alone and in combination was evaluated against strains of Staphylococcus aureus by measuring MBCs, FBC indexes and by the killing curve technique. Bactericidal titres were determined in sera from volunteers given ofloxacin alone or in combination with fosfomycin or vancomycin. FBC indices less than 0.75 were observed with fosfomycin, showing moderate synergy. FBC indices of 1 were seen with vancomycin. Killing kinetic experiments indicated that ofloxacin (1 and 4 mg/l) exerted a rapid bactericidal effect (99.9% killing in 4 h); the combination of ofloxacin and fosfomycin was synergistic for one of three strains, while killing kinetics of ofloxacin were unaltered by fosfomycin for two of three strains or by vancomycin for the three strains. Sera collected two hours after ofloxacin or fosfomycin had been administered had bactericidal titres less than 1/2. Bactericidal titres were significantly greater in sera from volunteers given the combination of these two drugs. Similar bactericidal titres were obtained in sera after the administration of vancomycin alone or in combination with ofloxacin. A loading dose of 400 mg ofloxacin with subsequent doses of 200 mg had no significantly prolonged effect on bactericidal titres.

[Transfer of ofloxacin into suction blister fluid after its oral administration]

After oral administration of 300 mg of ofloxacin (OFLX), the concentration of OFLX in serum peaked at 2 hours and reached 2.88 +/- 0.62 micrograms/ml (mean +/- S.D.). In the fluid of dermal blisters produced by suction, the peak value was 1.74 +/- 0.88 micrograms/ml at 4 hours. Pharmacokinetically, Cmax (maximum concentration), Tmax (time of maximum concentration), Ka (absorption rate constant) and AUC0-8hrs. (area under the concentration-time curve) were calculated as 2.65 micrograms/ml, 2.07 hours, 0.79 hr-1 and 14.5 micrograms.hr/ml in serum, and 1.59 micrograms/ml, 4.49 hours, 0.27 hr-1 and 10.1 micrograms.hr/ml, respectively. Therapeutic AUC (area under the curve above minimum effective concentration) were also calculated as 13.3 micrograms.hr/ml (0.14-12.4 hours) in serum, and 11.5 micrograms.hr/ml (0.42-17.3 hours).

Antagonism of wild-type and resistant Escherichia coli and its DNA gyrase by the tricyclic 4-quinolone analogs ofloxacin and S-25930 stereoisomers

The mechanism of action of the quinolone analogs ofloxacin and S-25930, which are unusual because of the presence of a third ring with an asymmetric carbon, was studied. Drug-resistant strains of Escherichia coli were selected by serial passage in the presence of ofloxacin, and a mutation was mapped near the gyrA gene of DNA gyrase. DNA gyrase containing the A subunit purified from this strain as compared with the isogenic wild-type strain exhibited increased resistance to ofloxacin, proving that the mutation was located in the gyrA gene. For S-25930, the S stereoisomer was more potent than the R isomer in inhibiting wild-type E. coli and DNA gyrase containing an A subunit isolated from this strain. Both isomers had decreased potency against the isogenic ofloxacin-resistant (gyrA) strain and its purified enzyme, but the S isomer remained more potent than the R isomer. These studies, using a combined genetic and biochemical approach, demonstrate (i) that DNA gyrase is a target of the tricyclics ofloxacin and S-25930, (ii) that serial exposure to ofloxacin can select resistance to tricyclic quinolone agents by mutation in the gyrA gene, and (iii) that the more potent antibacterial activity of S relative to R S-25930 correlates with increased activity against DNA gyrase for both wild-type and ofloxacin-resistant (gyrA) isogenic strains.

Decrease of caffeine elimination in man during co-administration of 4-quinolones

The single dose pharmacokinetics of caffeine (220-230 mg per dose) were investigated in 12 healthy male volunteers before and during treatment with ofloxacin (200 mg bd), ciprofloxacin (250 mg bd) and enoxacin (400 mg bd) with a cross-over study design. None of the parameters: mean elimination half-life (T1/2el), Cmax, total body clearance (Cltot) and the volume of distribution (aVd) of caffeine were noticeably altered by administration of ofloxacin. Striking changes were observed, however, after administration of enoxacin: the T1/2el was prolonged by as much as 260%, the Cmax increased by 41%; the aVd was reduced by 20% and Cltot by 78% (mean values). Treatment with ciprofloxacin led to a prolongation of T1/2el by 15%, to a decrease of aVd by 25% and to a 33% decrease of Cltot. The results of this intra-individual comparison of caffeine pharmacokinetic data demonstrate that treatment with ciprofloxacin and enoxacin may have a significant inhibitory effect on caffeine elimination.

Ofloxacin for prevention of bacterial infections in granulocytopenic patients

We studied the potential value of oral ofloxacin (200 mg twice daily) for selective decontamination and infection prevention in 40 granulocytopenic patients with acute leukemia, blast crisis of chronic myelogenous leukemia, hairy cell leukemia or severe aplastic anemia. The quality of selective decontamination was acceptable with rapid elimination of Enterobacteriaceae from the alimentary tract, only a slight decrease in concentrations of anaerobes in faeces, and a small number of newly acquired transient (twelve isolates in seven patients) or colonizing (six strains with 28 isolates in four patients) aerobic gram-negative rods and Staphylococcus aureus (one isolate) recovered from 672 surveillance cultures from faeces, oral washings and urine. Two of three patients colonized with ofloxacin-resistant Pseudomonas aeruginosa strains developed Pseudomonas infections. A total of twelve acquired infections was observed. Six were microbiologically documented infections, all caused by ofloxacin-resistant bacteria (two P. aeruginosa, two Staphylococcus epidermidis, one Aerococcus viridans, one Micrococcus sp.). Tolerance was acceptable with no serious side effects observed. Mean drug concentrations in serum and saliva were comparable to those determined in healthy volunteers and were found to be higher in saliva than in serum. We conclude that ofloxacin may be studied as an effective alternative to trimethoprim-sulfamethoxazole for selective decontamination and infection prevention in severely granulocytopenic patients. Careful monitoring of colonizing Pseudomonas spp. with decreased ofloxacin sensitivity, however, seems necessary.

Symposium on antimicrobial agents. The quinolones

The fluoroquinolones are a new class of antimicrobial agents structurally related to nalidixic acid. They have a broad spectrum of activity against pathogens, including Pseudomonas aeruginosa, other multiresistant gram-negative bacteria, and methicillin-resistant Staphylococcus aureus but not anaerobes. They are well absorbed after oral administration, and some achieve serum and tissue levels well exceeding the minimal inhibitory concentrations for susceptible bacteria. Adverse reactions are rare, and when they occur they are usually mild. Use of quinolones should be avoided in children because of possible damage to developing cartilage. These agents should prove useful in the treatment of urinary tract infections caused by bacteria resistant to other oral agents, bacterial gastroenteritis, and gonococcal infections. The use of quinolones may potentially reduce the cost of treatment of certain systemic infections caused by multiantimicrobial resistant organisms because outpatient oral therapy is possible.

Antiviral activity and inhibition of topoisomerase by ofloxacin, a new quinolone derivative

The antiviral activity of ofloxacin, a new quinolone derivative, against vaccinia virus (VV), herpes simplex virus (HSV) and influenza virus (InfV) was evaluated in both in vitro and in vivo experiments. As a result, ofloxacin showed inhibitory activity against VV in cultured mammalian cells, and prevented formation of pox tail lesions in VV-infected mice. However, it was less effective against HSV and InfV than VV. The antiviral activity of ofloxacin assessed by VV tail-lesion test was strongest when administered to mice through the oral route daily for five consecutive days post-infection. Nalidixic acid and novobiocin, well-known gyrase inhibitors, showed only weak antiviral activity in both in vitro and in vivo tests against VV. It was also demonstrated that ofloxacin inhibited virus-specific DNA and RNA syntheses. It was more inhibitory to VV topoisomerase than cellular topoisomerases. Thus, ofloxacin has selectivity for VV.

The efficacy and safety of ciprofloxacin and ofloxacin in chronic Pseudomonas aeruginosa infection in cystic fibrosis

The clinical efficacy and safety of ciprofloxacin and ofloxacin were compared in a prospective, randomized double blind, placebo combined cross-over study in 26 adult cystic fibrosis patients with chronic broncho-pulmonary Pseudomonas aeruginosa infection. Active treatment consisted of ciprofloxacin 750 mg orally twice daily or ofloxacin 400 mg orally twice daily; both treatments were given for 14 days, with three months between treatment periods; 21 patients completed both treatment periods. Treatment with both ciprofloxacin and ofloxacin was associated with a good clinical response as judged by clinical score, lung function tests and inflammatory parameters; no difference between ciprofloxacin and ofloxacin was found. Adverse reactions were seen in nine of 24 patients who received ciprofloxacin and in six of 23 who received ofloxacin. The majority were dyspeptic reactions or photosensitivity. No serious adverse reactions occurred. Three cases of treatment failure were found, one of which was associated with development of resistant P. aeruginosa during ofloxacin treatment. The mean MIC of both drugs increased during treatment but returned to pretreatment values within three months. Ciprofloxacin and ofloxacin seem to be valuable agents for intermittent treatment of chronic P. aeruginosa lung infection in adult cystic fibrosis patients.

In vitro activity of four fluoroquinolones against eighty-six isolates of mycobacteria

The in vitro activity of pefloxacin, norfloxacin, ofloxacin and ciprofloxacin against 86 strains of mycobacteria was evaluated by broth dilution. While Mycobacterium avium, Mycobacterium scrofulaceum and Mycobacterium chelonae were resistant to all four antibacterials, the susceptibility of the other species, Mycobacterium tuberculosis, Mycobacterium kansasii, Mycobacterium xenopi and Mycobacterium fortuitum, depended on the antibiotic. Ofloxacin and ciprofloxacin (MIC90: 0.5 - 2 mg/l) were more active than pefloxacin and norfloxacin (MIC90: 2 - 16 mg/l).

Susceptibility of Bordetella pertussis to five quinolone antimicrobic drugs

Five quinolone antimicrobic agents were tested to determine the mean inhibitory concentration (MIC) of each of 17 clinical strains of Bordetella pertussis by the agar dilution method. Ciprofloxacin demonstrated the best in vitro activity with an MIC90 of 0.06 microgram/ml. Norfloxacin, ofloxacin and enoxacin were also highly active with MIC90s of 0.25, 0.25, and 0.5, respectively. Cinoxacin was only moderately active (MIC90 4.0 microgram/ml).

New synthetic quinolone antibacterial agents and serum concentration of theophylline

The effect of pipemidic acid and five new synthetic antibacterial agents--norfloxacin, enoxacin, ofloxacin, ciprofloxacin, and pefloxacin--on the serum level of theophylline was studied in healthy male adult volunteers after concomitant oral administration of these agents with a slow release preparation of theophylline. The results indicated that enoxacin, ciprofloxacin, and pipemidic acid might decrease the clearance of theophylline in the liver, and the attention should be paid in clinical use when enoxacin or pipemidic acid is coadministered with theophylline.

Comparative pharmacokinetics of ciprofloxacin and ofloxacin in cystic fibrosis patients

The steady state pharmacokinetic properties of ciprofloxacin and ofloxacin were compared in cystic fibrosis patients. In a cross-over study eighteen adult patients with chronic Pseudomonas aeruginosa lung infection were given either oral ciprofloxacin 750 mg bid or oral ofloxacin 400 mg bid for two weeks. Three months later the alternative treatment was given. Concentrations were determined by a microbiological assay. Mean serum concentrations of ofloxacin (peak 5.9 mg/l) were higher than for ciprofloxacin (peak 4.0 mg/l). The time to reach maximal concentrations did not differ. The apparent total body clearance was significantly greater for ciprofloxacin, but renal clearances were similar. Relative to ofloxacin ciprofloxacin had a significantly shorter serum elimination half-life (3.4 vs. 6.4 h), showed less penetration into sputum (18% vs. 79%) and a lesser amount was recovered in urine (21% vs. 71% up to 12 h after dosing). No correlation was found between any pharmacokinetic parameter and change in pulmonary function.

[Ofloxacin in the therapy of Campylobacter pylori-positive duodenal ulcer. A prospective controlled randomized study]

50 patients with duodenal ulcer and Campylobacter pylori cultured from the antral mucosa were randomly divided into two groups of 25. They received either ranitidine 300 mg at night or the same dose of ranitidine combined with twice daily 200 mg ofloxacin. Endoscopic check and biopsy for histological and microbiological tests were performed every two weeks until demonstrable cure of the ulcer. After two weeks the cure rates were 44 and 80%, respectively, after four weeks 68 and 92%, and after six weeks 88 and 100%. The difference in healing time between ranitidine alone and ranitidine plus ofloxacin was statistically significant (P less than 0.025). Campylobacter pylori was no longer demonstrable in two of 25 patients after ranitidine alone and in 24 of 25 after ranitidine-ofloxacin. The minimal inhibitory concentration of ofloxacin against tested Campylobacter pylori strains was 0.5-1.0 micrograms/ml. Both groups were comparable as to age and sex distribution; duration of history of ulcer, and number of previous ulcers; nicotine and alcohol consumption; intake of nonsteroidal antirheumatic drugs; other previous treatment; size and complications of the ulcers; and number of accompanying diseases. The results speak for Campylobacter pylori playing a role in the pathogenesis of duodenal ulcer.

Susceptibility of urinary isolates of Corynebacterium group D2 to fifteen antimicrobials and acetohydroxamic acid

The susceptibility in vitro of 28 Corynebacterium group D2 strains, mainly isolated from urine, to fifteen antimicrobial agents and acetohydroxamic acid (AHA) was determined at two pH values. The bactericidal activity of four antimicrobials and AHA was studied in three reference strains in broth at two pHs and with two inoculum sizes. The activity of norfloxacin and AHA, against one selected strain, in broth and human urine, was also determined. Vancomycin, ofloxacin and norfloxacin were the most active agents tested. Norfloxacin acted bactericidally in broth and in human urine but was not synergic with AHA.

[Clinical evaluation of ofloxacin against complicated urinary tract infections]

Clinical efficacy of ofloxacin (OFLX) against complicated urinary tract infections was examined in 20 patients. OFLX was administrated orally at a dose of 200 mg, three times (daily 600 mg) for 14 to 102 days. The overall clinical efficacy was rated excellent in 8 cases (40%), moderate in 7 cases (35%) and poor in 5 cases (25%) with a total efficacy of 75%. Bacteriological efficacy, 17 out of 24 strains (70.8%) isolated were eradicated after OFLX administration. The strains that appeared after OFLX treatment were P. cepacia and Candida sp. No severe side effects were found in these patients.