Activities of new quinoline derivatives against genital pathogens

Hueneman K, Bartram J, Stepanchick E, R. Bennett J, E. Culver-Cochran A, Bolanos LC, Uible E, Choi K, Wunderlich M, Perentesis JP, M. Chlon T, Filippi MD, Starczynowski DT. The deubiquitinase USP15 modulates cellular redox and is a therapeutic target in acute myeloid leukemia

Ubiquitin-specific peptidase 15 (USP15) is a deubiquitinating enzyme implicated in critical cellular and oncogenic processes. We report that USP15 mRNA and protein are overexpressed in human acute myeloid leukemia (AML) as compared to normal hematopoietic progenitor cells. This high expression of USP15 in AML correlates with KEAP1 protein and suppression of NRF2. Knockdown or deletion of USP15 in human and mouse AML models significantly impairs leukemic progenitor function and viability and de-represses an antioxidant response through the KEAP1-NRF2 axis. Inhibition of USP15 and subsequent activation of NRF2 leads to redox perturbations in AML cells, coincident with impaired leukemic cell function. In contrast, USP15 is dispensable for human and mouse normal hematopoietic cells in vitro and in vivo. A preclinical small-molecule inhibitor of USP15 induced the KEAP1-NRF2 axis and impaired AML cell function, suggesting that targeting USP15 catalytic function can suppress AML. Based on these findings, we report that USP15 drives AML cell function, in part, by suppressing a critical oxidative stress sensor mechanism and permitting an aberrant redox state. Furthermore, we postulate that inhibition of USP15 activity with small molecule inhibitors will selectively impair leukemic progenitor cells by re-engaging homeostatic redox responses while sparing normal hematopoiesis.

Quinolones: Mechanism, Lethality and Their Contributions to Antibiotic Resistance

Fluoroquinolones (FQs) are arguably among the most successful antibiotics of recent times. They have enjoyed over 30 years of clinical usage and become essential tools in the armoury of clinical treatments. FQs target the bacterial enzymes DNA gyrase and DNA topoisomerase IV, where they stabilise a covalent enzyme-DNA complex in which the DNA is cleaved in both strands. This leads to cell death and turns out to be a very effective way of killing bacteria. However, resistance to FQs is increasingly problematic, and alternative compounds are urgently needed. Here, we review the mechanisms of action of FQs and discuss the potential pathways leading to cell death. We also discuss quinolone resistance and how quinolone treatment can lead to resistance to non-quinolone antibiotics.

In vitro and in vivo activities of sparfloxacin, other quinolones, and tetracyclines against Chlamydia trachomatis

Sparfloxacin was more potent than other quinolones (tosufloxacin, lomefloxacin, ciprofloxacin, ofloxacin, fleroxacin, enoxacin, and norfloxacin) and as potent as minocycline and doxycycline in activity against Chlamydia trachomatis in vitro and in vivo. Sparfloxacin was more bactericidal than minocycline against C. trachomatis D/UW-3/Cx.

In vitro activity of temafloxacin against pathogens causing sexually transmitted diseases

The fluoroquinolones represent a new therapeutic alternative for the treatment of many sexually transmitted diseases, especially those caused by Neisseria gonorrhoeae, Chlamydia trachomatis, Mycoplasma hominis, and Urea-plasma urealyticum. In vitro studies have demonstrated the 90% minimal inhibitory concentrations (MIC90s) of temafloxacin for these pathogens to be less than 0.03 micrograms/mL for N. gonorrhoeae; 0.25 micrograms/mL for C. trachomatis; 0.125-2 micrograms/mL for M. hominis; and 4 micrograms/mL for U. urealyticum. These concentrations are equal to or less than those achievable in plasma following a 400-mg temafloxacin oral dose given twice daily. Based on temafloxacin's antimicrobial activity and pharmacokinetic profile, it appears to be an excellent agent for the treatment of patients with gonococcal or nongonococcal urethritis and/or cervicitis.

In vitro susceptibilities of Mycoplasma pneumoniae, Mycoplasma hominis, and Ureaplasma urealyticum to sparfloxacin and PD 127391

The in vitro activities of two investigational quinolones, sparfloxacin (previously designated AT 4140) and PD 127391, were determined for 30 strains each of Mycoplasma pneumoniae, Mycoplasma hominis, and Ureaplasma urealyticum and compared with those of ciprofloxacin, tetracycline, clindamycin, and erythromycin. Erythromycin was the most active compound against M. pneumoniae (maximum MIC, less than 0.008 microgram/ml). PD 127391 (MICs, less than 0.008 to 0.031 microgram/ml), sparfloxacin (MICs, less than 0.008 to 0.25 microgram/ml), clindamycin (MICs, less than 0.008 to 0.5 microgram/ml), and tetracycline (MICs, 0.063 to 0.25 microgram/ml) were superior to ciprofloxacin (MICs, 0.5 to 2 microgram/ml). Sparfloxacin and PD 127391 were active against M. hominis (MICs, less than 0.008 to 0.031 microgram/ml for each) at concentrations comparable to those of clindamycin (MICs, less than 0.008 to 0.063 microgram/ml) and at concentrations lower than those of ciprofloxacin (MICs, 0.125 to 0.5 microgram/ml). As expected, M. hominis was resistant to erythromycin (MICs, 32 to greater than or equal to 256 micrograms/ml). For U. urealyticum, PD 127391 (MICs, 0.031 to 0.5 microgram/ml) and sparfloxacin (MICs, 0.063 to 1 microgram/ml) were superior to erythromycin (MICs, 0.25 to 4 micrograms/ml), ciprofloxacin (MICs, 0.5 to 8 micrograms/ml), and clindamycin (MICs, 0.25 to 64 micrograms/ml. Both new quinolones were equally active against tetracycline-susceptible as well as resistant strains of M. hominis and U. urealyticum. The possible influence of medium components and/or pH on MICs was evaluated by testing a Staphylococcus aureus reference strain with each antibiotic in SP-4 broth and 10-B broth and comparing the results with published MICs for this strain. MICs determined in 10-B broth for erythromycin were affected most. This study shows that the activities of sparfloxacin and PD 127391 are similar to one another and comparable or superior to those of other drugs used to treat mycoplasmal infections. The MICs of both new quinolones were consistently 2 to several dilutions lower than those of ciprofloxacin for each species.

Patient costs for prophylaxis and treatment of obstetric and gynecologic surgical infections

The use of newer broad-spectrum antimicrobials for prophylaxis and treatment in obstetric and gynecologic surgery can reduce patient morbidity and hospital costs. For prophylaxis, a single dose of a cephalosporin with a long elimination half-life can be as effective as a more prolonged course. Single-dose prophylaxis reduces not only toxicity and cost to the patient but also the likelihood of colonization of the vagina by resistant organisms. Treatment regimens for postoperative pelvic infections should have broad-spectrum coverage against aerobic and anaerobic pathogens to ensure high cure rates and prevent subsequent abscess formation. With the introduction of newer cephalosporins and penicillin combinations that include a beta-lactamase inhibitor, it is now possible to treat these polymicrobial infections effectively with monotherapy. Compared with traditional antibiotic combinations, these drugs can reduce side effects and the costs of drug administration as well as the need for therapeutic monitoring. The use of oral antibiotics to complete a course of treatment can also help decrease the high costs of parenteral antibiotic therapy and hospitalization.

A review of the antimicrobial activity of the fluoroquinolones

The evolution of the fluoroquinolones is described, and structure-activity relationships outlined. The in-vitro antimicrobial activities of ciprofloxacin, enoxacin, norfloxacin, ofloxacin and pefloxacin against a wide range of organisms are critically reviewed. In-vitro factors influencing fluoroquinolone activity are discussed. Reports of the acquisition of resistance to the fluoroquinolones are evaluated. Finally, possible future directions for this group of antibiotics are discussed.

Comparison of ofloxacin and ceftriaxone in the treatment of uncomplicated gonorrhea caused by penicillinase-producing and non-penicillinase-producing strains

Eighty-nine patients with uncomplicated gonorrhea, including 31 patients (34.8%) infected with penicillinase-producing strains of Neisseria gonorrhoeae, were treated with oral ofloxacin (single 400-mg dose) or intramuscular ceftriaxone (250-mg dose). All 47 patients who received ofloxacin and 41 of 42 patients who received ceftriaxone were cured.

Quinolone antibacterial agents for the treatment of genitourinary tract infections

The fluoroquinolones have expanded the therapeutic options available for the treatment of genitourinary tract infections. Their ease of oral administration, favourable pharmacokinetics, low incidence of adverse reactions, and broad spectrum of in vitro activity against aerobic and facultative organisms make them especially suitable for treating bacteriuria, particularly when pathogens are resistant to other available oral agents. Their efficacy has also been established in the treatment of prostatis, gonorrhea and chancroid. They have lower in vitro activity against chlamydia, ureaplasma and anaerobes, and their role in the treatment of non-gonococcal urethritis, vaginitis and acute pelvic inflammatory disease is less well established.

Ciprofloxacin in patients with bacteremic infections. The Spanish Group for the Study of Ciprofloxacin

The efficacy and safety of ciprofloxacin in the treatment of 68 episodes of bacteremia were studied. Patients were treated intravenously (30 cases), orally (13 cases), or with sequential intravenous/oral therapy (25 cases). Intravenous doses ranged from 200 to 400 mg per day and oral doses ranged from 1,000 to 1,500 mg per day. According to the criteria of McCabe and Jackson, 39 cases had nonfatal and 29 had ultimately fatal underlying diseases. The clinical condition of patients at the start of therapy was critical or poor in 40 cases and fair or good in 28. Sixty-four of the 68 episodes of bacteremia were monomicrobial and the remaining four were polymicrobial. The causative micro-organisms were: Escherichia coli (18 episodes), Pseudomonas aeruginosa (13 episodes), Acinetobacter sp. (10 episodes), Salmonella sp. (seven episodes), Enterobacter sp. (six episodes), Proteus sp. (four episodes), Serratia sp. (four episodes), Haemophilus influenzae (three episodes), Klebsiella sp. (three episodes), Staphylococcus aureus (2 episodes), and Morganella morganii (two episodes). Overall clinical efficacy of ciprofloxacin was 94 percent (64 of 68 patients). Bacteremia persisted in four patients (failure rate of 6 percent). Five organisms persisted: Acinetobacter sp. (two patients), P. aeruginosa (one patient), Enterobacter sp. (one patient), and Serratia sp. (one patient). Side effects were phlebitis associated with intravenous administration (four cases), dizziness (four cases), and superinfection (six cases). Superinfecting organisms and sites were as follows: Enterococcus faecalis, wound (2 cases); Candida sp., urinary tract infection (one case); Acinetobacter anitratus (ciprofloxacin resistant), urinary tract infection (one case); Staphylococcus epidermidis, blood (one case); and Clostridium perfringens, blood (one case). Ciprofloxacin administered either intravenously, orally, or intravenously followed by the oral route is effective therapy in the treatment of severe bacteremic infections.

Ofloxacin: a review

Ofloxacin is a new fluorinated quinolone antibiotic with a broad spectrum of activity against a variety of gram-positive and -negative bacteria including Enterobacteriaceae, Pseudomonas aeruginosa, and methicillin-resistant Staphylococcus aureus. In addition, ofloxacin has significant activity against Neisseria gonorrhoeae, Chlamydia trachomatis, and Mycobacterium tuberculosis and this may give rise to new indications for the class of quinolone antibiotics. Clinical trials to date have demonstrated the efficacy of ofloxacin in the treatment of lower respiratory tract infections, urinary tract infections, and sexually transmitted diseases. Adverse effects to ofloxacin are usually mild and include gastrointestinal, central nervous system, and hypersensitivity reactions. Significant drug interactions with ofloxacin have not been reported.

Fluoroquinolone antimicrobial agents

The fluoroquinolones, a new class of potent orally absorbed antimicrobial agents, are reviewed, considering structure, mechanisms of action and resistance, spectrum, variables affecting activity in vitro, pharmacokinetic properties, clinical efficacy, emergence of resistance, and tolerability. The primary bacterial target is the enzyme deoxyribonucleic acid gyrase. Bacterial resistance occurs by chromosomal mutations altering deoxyribonucleic acid gyrase and decreasing drug permeation. The drugs are bactericidal and potent in vitro against members of the family Enterobacteriaceae, Haemophilus spp., and Neisseria spp., have good activity against Pseudomonas aeruginosa and staphylococci, and (with several exceptions) are less potent against streptococci and have fair to poor activity against anaerobic species. Potency in vitro decreases in the presence of low pH, magnesium ions, or urine but is little affected by different media, increased inoculum, or serum. The effects of the drugs in combination with a beta-lactam or aminoglycoside are often additive, occasionally synergistic, and rarely antagonistic. The agents are orally absorbed, require at most twice-daily dosing, and achieve high concentrations in urine, feces, and kidney and good concentrations in lung, bone, prostate, and other tissues. The drugs are efficacious in treatment of a variety of bacterial infections, including uncomplicated and complicated urinary tract infections, bacterial gastroenteritis, and gonorrhea, and show promise for therapy of prostatitis, respiratory tract infections, osteomyelitis, and cutaneous infections, particularly when caused by aerobic gram-negative bacilli. Fluoroquinolones have also proved to be efficacious for prophylaxis against travelers' diarrhea and infection with gram-negative bacilli in neutropenic patients. The drugs are effective in eliminating carriage of Neisseria meningitidis. Patient tolerability appears acceptable, with gastrointestinal or central nervous system toxicities occurring most commonly, but only rarely necessitating discontinuance of therapy. In 17 of 18 prospective, randomized, double-blind comparisons with another agent or placebo, fluoroquinolones were tolerated as well as or better than the comparison regimen. Bacterial resistance has been uncommonly documented but occurs, most notably with P. aeruginosa and Staphylococcus aureus and occasionally other species for which the therapeutic ratio is less favorable. Fluoroquinolones offer an efficacious, well-tolerated, and cost-effective alternative to parenteral therapies of selected infections.

In-vitro activity of ofloxacin against Chlamydia trachomatis

The in-vitro activity of ofloxacin was evaluated against recently isolated Chlamydia trachomatis strains from patients suffering from non-gonococcal urethritis. The minimal inhibitory concentration (MIC) proved to be 1 mg/l against 8 of the 10 strains assayed (the MICs for the other two strains were 0.5 and 2 mg/l). The data obtained confirm that ofloxacin is active against Chlamydia trachomatis at concentrations achievable with the routine dosage regimen. The drug may thus be regarded as potentially useful for the treatment of non-gonococcal urethritis due to Chlamydia.

Comparative in vitro activity of norfloxacin against resistant Neisseria gonorrhoeae

The in vitro activity of seven antibiotics against 52 isolates of Neisseria gonorrhoeae was determined. Against penicillinase-producing Neisseria gonorrhoeae, ceftriaxone was the most active agent (MIC90 0.015 micrograms/ml), followed by ceftizoxime and norfloxacin (MIC90 0.03-0.125 micrograms/ml). Against spectinomycin-resistant Neisseria gonorrhoeae, the most active agents were ceftizoxime, ceftriaxone and norfloxacin (MIC90 0.015-0.125 micrograms/ml). Ceftizoxime, ceftriaxone and norfloxacin were also the most active agents against tetracycline-resistant Neisseria gonorrhoeae (MIC90 0.06-0.125 micrograms/ml). Overall, the rank order of activity from the most to the least active agent was as follows: ceftizoxime (MIC90 0.015 micrograms/ml); ceftriaxone (MIC90 0.06 micrograms/ml); norfloxacin (MIC90 0.125 micrograms/ml); cefoxitin (MIC90 2 micrograms/ml); tetracycline (MIC90 8 micrograms/ml); penicillin (MIC90 greater than 8 micrograms/ml); and spectinomycin (MIC90 greater than 128 micrograms/ml).

In vitro activity of lomefloxacin (SC 47111 or NY-198) against Chlamydia trachomatis strains

The in vitro activity of lomefloxacin (SC 47111 or NY-198), a new quinolone antibiotic, against 11 strains of Chlamydia trachomatis was determined and compared to doxycycline, norfloxacin, and ciprofloxacin. Lomefloxacin had anti-chlamydial activity comparable to that of ciprofloxacin. (MIC and MBC90, 2 micrograms/ml).

In vitro activity of lomefloxacin against Chlamydia trachomatis, Neisseria gonorrhoeae, Haemophilus ducreyi, Mycoplasma hominis, and Ureaplasma urealyticum

The in vitro activity of lomefloxacin, a new difluorinated quinolone antimicrobial was compared to comparative agents against organisms causing sexually transmitted diseases. Against Chlamydia trachomatis, Mycoplasma hominis, Ureaplasma urealyticum, Neisseria gonorrhoeae, and Haemophilus ducreyi, lomefloxacin exhibited MIC90 of 2.0, 8.0, 8.0, less than or equal to 0.015, and 0.003 micrograms/ml, respectively. Overall, the lomefloxacin activity was very similar to ciprofloxacin.

Susceptibilities of genital mycoplasmas to the newer quinolones as determined by the agar dilution method

The increasing resistance of genital mycoplasmas to tetracycline poses a problem because tetracycline is one of the few antimicrobial agents active against Mycoplasma hominis, Ureaplasma urealyticum, chlamydiae, gonococci, and other agents of genitourinary-tract disease. Since the quinolones are a promising group of antimicrobial agents, the susceptibilities of M. hominis and U. urealyticum to the newer 6-fluoroquinolones were determined by the agar dilution method. Ciprofloxacin, difloxacin, and ofloxacin had good activity against M. hominis, with the MIC for 50% of isolates tested (MIC50) being 1 microgram/ml. Fleroxacin, lomefloxacin, pefloxacin, and rosoxacin had MIC50s of 2 micrograms/ml. Enoxacin, norfloxacin, and amifloxacin had MIC50s of 8 to 16 micrograms/ml, and cinoxacin and nalidixic acid were inactive (MIC50, greater than or equal to 256 micrograms/ml). Overall, the activities of 6-fluoroquinolones for ureaplasmas were similar to those for M. hominis, with MICs being the same or twofold greater. The most active 6-fluoroquinolones against ureaplasmas were difloxacin, ofloxacin, and pefloxacin, with MIC50s of 1 to 2 micrograms/ml. Ciprofloxacin was unusual in that the MIC50 for M. hominis was 1 microgram/ml, whereas the MIC50 for ureaplasmas was 8 micrograms/ml. Since the MIC50s for the most active quinolones approximate achievable concentrations in blood and urine, quinolones have promise in treating mycoplasmal infections.

In vitro activities of temafloxacin (A-62254) and four other antibiotics against Chlamydia trachomatis

The in vitro activity of temafloxacin (A-62254), a new quinolone antibiotic, against 13 strains of Chlamydia trachomatis was determined and compared with those of doxycycline, norfloxacin, ciprofloxacin, and difloxacin. Temafloxacin and difloxacin were the most active quinolones tested, with bactericidal activity comparable to that of doxycycline.

In vitro activities of ofloxacin and four other new quinoline-carboxylic acids against Chlamydia trachomatis

The in vitro activities of five new quinoline-carboxylic acids against 2 reference strains and 45 clinical isolates of Chlamydia trachomatis of genital origin were compared with the activities of minocycline and doxycycline. Ofloxacin was the third most active agent (after the two tetracyclines), followed by ciprofloxacin, NY-198, and AM-833.

In vitro susceptibilities of mycoplasmas and ureaplasmas to new macrolides and aryl-fluoroquinolones

In vitro activities of the new macrolides clarithromycin, previously designated A-56268 (TE-031), and A-63075 and of the aryl-fluoroquinolones difloxacin (A-56619) and temafloxacin (A-62254) against 14 strains of Mycoplasma pneumoniae, 20 strains of Mycoplasma hominis, and 28 strains of Ureaplasma urealyticum were compared with that of erythromycin. All three macrolides inhibited growth of M. pneumoniae at less than 0.125 micrograms/ml. No macrolide was active against M. hominis. For five strains of U. urealyticum, MICs were greater than 256 micrograms/ml for all 3 macrolides. Excluding these, no other strain of U. urealyticum had an initial MIC of clarithromycin of greater than 1 microgram/ml, while five had initial MICs of erythromycin which were greater than 4 micrograms/ml. A-63075 was the least active of the three macrolides against ureaplasmas. Temafloxacin and difloxacin had similar activities against all three species, initially inhibiting 90% of M. pneumoniae strains at 2 and 8 micrograms/ml, 90% of M. hominis strains at 2 and 4 micrograms/ml, and 90% of U. urealyticum strains at 4 and 8 micrograms/ml, respectively. Additional pharmacokinetic and clinical trials with the new macrolides and quinolones with mycoplasmal or ureaplasmal infections are indicated.

Fluoroquinolone antibiotics. Microbiology, pharmacokinetics and clinical use

The newer fluoroquinolones are a major advance in antimicrobial chemotherapy. They inhibit the supercoiling activity of the DNA gyrase enzyme, thus exerting their antibacterial action on DNA and RNA synthesis, resulting in a biphasic response and killing of susceptible organisms. The newer fluoroquinolones have an extended antimicrobial spectrum compared to their older congeners, and are highly active against most Gram-negative pathogens including the Enterobacteriaceae and Pseudomonas aeruginosa. While Staphylococcus aureus and coagulase-negative staphylococci are usually susceptible to the fluoroquinolones, streptococci are generally more resistant and enterococci are resistant. All of the newer fluoroquinolones may be administered orally and most of them have been administered parenterally. They are widely distributed in the body, attaining therapeutic concentrations in most tissues. All of the fluoroquinolones have long half-lives and may be administered once or twice daily. The fluoroquinolones have proved effective in many infections, including uncomplicated or complicated urinary tract infections, respiratory tract infections, gonorrhoea, bacterial gastroenteritis, and soft tissue infections due to Gram-negative organisms. In general, success has been notable in the management of Gram-negative infections but less so with Gram-positive infections. Resistance has occurred and is proving a problem with P. aeruginosa in some cystic fibrosis patients, but as yet no plasmid-mediated resistance has developed. Cross-resistance occurs between the quinolones but only rarely with other classes of antibacterial drugs. The fluoroquinolones have an excellent safety record and their adverse effects, which include hypersensitivity reactions, dizziness, headache, gastrointestinal disturbance and minor haematological abnormalities are usually mild and transient. However, the fluoroquinolones have been found to damage juvenile weight-bearing joints in animals and are therefore only to be used with caution in children; transient arthralgia has been reported in a cystic fibrotic teenager on long term ciprofloxacin therapy. All of the fluoroquinolones except ofloxacin are associated with a variable increase in the serum concentration of theophylline, warfarin and caffeine. Thus, the fluoroquinolones are an attractive option in the management of many infections. Cost and possible resistance, however, should counsel caution in their use, and may limit them to situations where a cheaper antimicrobial of equivalent efficacy is not available.

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

Enoxacin is a new addition to the class of 4-quinolone antibacterial drugs. It has a broad spectrum of in vitro antibacterial activity, and is particularly potent against Gram-negative organisms and staphylococci. The pharmacokinetic profile of enoxacin is similar to that of ofloxacin, achieving higher plasma and tissue concentrations and possessing a longer half-life than norfloxacin or ciprofloxacin. In comparative studies, clinical and/or bacteriological efficacy was comparable or (in studies which statistically analysed the results) not significantly different between enoxacin and amoxycillin in acute cystitis, acute Gram-negative exacerbations of chronic bronchitis and acute or chronic otitis media, between enoxacin and cephalexin in skin, skin structure and soft tissue infections, between enoxacin and trimethoprim in acute cystitis, between enoxacin and co-trimoxazole in complicated urinary tract infection and between enoxacin and pipemidic acid in suppurative otitis media. Significantly (p less than 0.01) more clinical and/or bacteriological cures were effected by enoxacin than pipemidic acid in acute cystitis and complicated urinary tract infection. In uncomplicated gonococcal infections single oral doses of enoxacin were effective in over 90% of patients. Enoxacin is a well-tolerated, orally active broad spectrum antibacterial drug which should prove a worthwhile alternative to currently available antibacterial therapy.

In vitro activities of T-3262, NY-198, fleroxacin (AM-833; RO 23-6240), and other new quinolone agents against clinically isolated Chlamydia trachomatis strains

The in vitro activities of three newly developed quinolone drugs (T-3262, NY-198, and fleroxacin [AM-833; RO 23-6240]) against 10 strains of clinically isolated Chlamydia trachomatis were assessed and compared with those of other quinolones and minocycline. T-3262 (MIC for 90% of isolates tested, 0.1 microgram/ml) was the most active of the quinolones. The NY-198 and fleroxacin MICs for 90% of isolates were 3.13 and 62.5 micrograms/ml, respectively.

Biotypes, serotypes, and susceptibility to antibiotics of 60 Haemophilus influenzae strains from genitourinary tracts

Sixty strains of Haemophilus influenzae were isolated from the genitourinary tracts of adults: 19 from cervicovaginal secretions, one from a woman with bartholinitis, 37 from urethral exudates, and three from urine. Non-capsulated strains were recovered predominantly, and biotype III accounted for 28 isolates and biotype IV for 25. Many of the H influenzae strains were found to be resistant to one or more of the antibiotics commonly used against sexually transmitted diseases. Resistance to tetracycline was prevalent and was found in 17 of the strains. Ten strains were ampicillin resistant and beta lactamase producing. Kanamycin resistance was less common (two strains). Trospectomycin (U-63366), a new spectinomycin analogue, was eight to 16 times more active than spectinomycin. All the quinolones tested were very active against all strains and may provide an effective alternative for the treatment of resistant H influenzae in genitourinary infections.

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

Ciprofloxacin is one of a new generation of fluorinated quinolones structurally related to nalidixic acid. The primary mechanism of action of ciprofloxacin is inhibition of bacterial DNA gyrase. It is a broad spectrum antibacterial drug to which most Gram-negative bacteria are highly susceptible in vitro and many Gram-positive bacteria are susceptible or moderately susceptible. Unlike most broad spectrum antibacterial drugs, ciprofloxacin is effective after oral or intravenous administration. Ciprofloxacin has been most extensively studied following oral administration. It attains concentrations in most tissues and body fluids which are at least equivalent to the minimum inhibitory concentration designated as the breakpoint for bacterial susceptibility in vitro. The results of clinical trials with orally and intravenously administered ciprofloxacin have confirmed the potential for its use in a wide range of infections, which was suggested by its in vitro antibacterial and pharmacokinetic profiles. It has proven an effective treatment for many types of systemic infections as well as for both acute and chronic infections of the urinary tract. Ciprofloxacin generally appeared to be at least as effective as alternative orally administered antibacterial drugs in the indications in which they were compared, and in some indications, to parenterally administered antibacterial therapy. However, further studies are needed to fully clarify the comparative efficacy of ciprofloxacin and standard antibacterial therapies. Bacterial resistance to ciprofloxacin develops infrequently, both in vitro and clinically, except in the setting of pseudomonal respiratory tract infections in cystic fibrosis patients. The drug is also well tolerated. Thus, as an orally active, broad spectrum and potent antibacterial drug, ciprofloxacin offers a valuable alternative to broad spectrum parenterally administered antibacterial drugs for use in a wide range of clinical infections, including difficult infections due to multiresistant pathogens.

Ofloxacin: its pharmacology, pharmacokinetics, and potential for clinical application

Ofloxacin is a 4-quinolone antibiotic with rapid bactericidal activity against a wide variety of organisms. Its proposed mechanism of activity is interference with DNA gyrase, an enzyme essential for the replication of bacterial DNA. In vitro activity of ofloxacin includes a variety of aerobic and anaerobic bacteria. Enteric gram-negative bacilli and cocci are generally sensitive to ofloxacin; nonaeruginosa strains of Pseudomonas are less so. Numerous bacterial pathogens of the gastrointestinal tract are also sensitive to the drug. Although its MIC values for gram-positive aerobic organisms are generally higher, ofloxacin's bactericidal activity against these organisms is considered by some to be adequate, and superior to that of most other fluoroquinolones. Ofloxacin is well absorbed after oral administration. Wide tissue and body fluid distribution is demonstrated. Urinary excretion is thought to be the primary route of elimination, with 80% of the dose recovered in the urine within 24 hours. The serum half-life ranges between 2.9 and 9 hours in a dose-dependent manner. Only modest accumulation is reported after multiple-dose administration. Clinical trials using daily dosages of 100-800 mg/day in single or divided doses have been reported in the treatment of a variety of conditions such as skin and soft tissue infections, tonsillitis, sexually transmitted disease, respiratory tract infections, cystitis, and complicated and uncomplicated urinary tract infections. English reports of these trials, however, are generally limited to abstract form, making evaluation of trial design difficult. Side effects most frequently encountered include gastrointestinal and central nervous system reactions.

Ciprofloxacin: chemistry, mechanism of action, resistance, antimicrobial spectrum, pharmacokinetics, clinical trials, and adverse reactions

Ciprofloxacin, considered a benchmark when comparing new fluoroquinolones, shares with these agents a common mechanism of action: inhibition of DNA gyrase. While ciprofloxacin demonstrated a fairly good activity against gram-positive bacteria, it is against gram-negative organisms that it proved to be more potent than other fluoroquinolones. It is the most active quinolone against Pseudomonas aeruginosa, with MIC90s on the order of 0.5 micrograms/ml. When given orally, ciprofloxacin exhibited 70% bioavailability and attained peak serum levels ranging between 1.5 and 2.9 micrograms/ml after a single 500-mg dose. Nineteen percent of an oral dose was excreted as metabolites in both urine and feces. In most cases, body fluids and tissue concentrations equaled or exceeded those in concurrent serum samples. In clinical trials, oral and intravenous ciprofloxacin yielded similar clinical and bacteriologic results compared to standard therapy in a wide array of systemic infections, including lower and upper urinary tract infections; gonococcal urethritis; skin, skin structure, and bone infections; and respiratory tract and gastrointestinal tract infections. Major benefits with the oral form of this quinolone are expected in chronic pyelonephritis and bone infections, and in pulmonary exacerbations in patients with cystic fibrosis. Emergence of ciprofloxacin-resistant microorganisms has been noted in clinical practice, primarily Pseudomonas aeruginosa and Staphylococcus aureus. The most frequent side effects are related to the gastrointestinal tract; but attention should be given to adverse central nervous system effects.

Norfloxacin: clinical pharmacology and clinical use

Norfloxacin, a nalidixic acid analog, is the first of the fluorinated quinolinecarboxylic acids to be marketed in the United States. It demonstrates potent antibacterial activity against aerobic, gram-negative bacteria including the Enterobacteriaceae, gentamicin-resistant Pseudomonas aeruginosa, and penicillin-resistant Neisseria gonorrhoeae. Norfloxacin exhibits good activity against methicillin-resistant and -sensitive Staphylococcus aureus, but less activity against most other aerobic, gram-positive organisms. Anaerobic bacteria are resistant to the drug. Resistance to norfloxacin is not plasmid mediated, but is secondary to bacterial mutation, and occurs less frequently than nalidixic acid resistance. Its pharmacokinetic properties after a 400-mg oral dose consist of a peak serum concentration of 1.3-1.58 micrograms/ml, an elimination half-life of 3-7 hours, and good penetration into kidney and prostatic tissues. Renal excretion is the major route of elimination. Norfloxacin is highly effective in the treatment of uncomplicated and complicated urinary tract infections, and gonococcal urethritis. Adverse effects are generally well tolerated and usually do not require discontinuation of therapy.

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

Ofloxacin is one of a new generation of fluorinated quinolones structurally related to nalidixic acid. It is an orally administered broad spectrum antibacterial drug active against most Gram-negative bacteria, many Gram-positive bacteria and some anaerobes. Ciprofloxacin is the only other quinolone with superior in vitro antibacterial activity. However, the pharmacokinetic profile of ofloxacin is superior to that of ciprofloxacin, with more rapid absorption and a peak serum concentration several times higher. Moreover, ofloxacin achieves high concentrations in most tissues and body fluids. The results of clinical trials with ofloxacin have confirmed the potential for use in a wide range of infections, which was indicated by its in vitro antibacterial and pharmacokinetic profiles. It has proven effective against a high percentage of infections caused by Gram-negative organisms, slightly less effective against Gram-positive infections, and effective against some anaerobic infections. Clinical efficacy has also been confirmed in a variety of systemic infections as well as in acute and chronic urinary tract infections, and ofloxacin has generally appeared to be at least as effective as alternative orally administered antibacterial drugs. Ofloxacin is well tolerated and, although experience with the drug in clinical practice to date is limited, bacterial resistance does not appear to develop readily. Thus, ofloxacin is an orally active drug which offers a valuable alternative to other broad spectrum antibacterial drugs.

Acute nongonococcal epididymitis. Aetiological and therapeutic aspects

In this study, 20 men suffering from acute nongonococcal epididymitis were treated with ofloxacin 200mg bid given orally for 2 weeks. Patients were re-examined after 2, 6, and 12 weeks. The outcome was assessed both clinically and microbiologically. Two weeks after start of therapy, the causative agent (Chlamydia trachomatis) was still present in only 1 patient, although local painful swelling of the epididymis persisted in 14 men. During the follow-up period, local signs of epididymitis decreased. After 12 weeks, an eradication of the causative micro-organisms was found in 16 of 20 cases. In 4 men, infection by the primary pathogen persisted: Escherichia coli (2); Pseudomonas aeruginosa (1) and C. trachomatis (1). Local pain and swelling was still detected in 6 of 20 men.

Single doses of ofloxacin in uncomplicated gonorrhoea

The clinical efficacies of 2 different single-dose oral treatments of ofloxacin were evaluated in a double-blind, randomised study of 60 males with gonococcal urethritis. 30 patients received a single dose of ofloxacin 100mg and 30 received a single dose of ofloxacin 200mg. The minimal inhibitory concentrations of ofloxacin against all isolates were less than or equal to 0.25 mg/L. Neisseria gonorrhoeae was eradicated from all 50 patients evaluated and clinical cure was achieved in 84%. In total, 8 patients developed post-gonococcal urethritis, although there was a significantly (p less than 0.05) lower rate of post-gonococcal urethritis in the group treated with ofloxacin 200mg. In conclusion, a single oral dose of ofloxacin 100mg could be an alternative treatment for uncomplicated gonorrhoea.

In vitro activity of A-56619 (difloxacin), A-56620, and other new quinolone antimicrobial agents against genital pathogens

The in vitro activities of two new carboxyquinolones, A-56619 (difloxacin) and A-56620, were compared with those of ciprofloxacin, norfloxacin, and ofloxacin against genital tract pathogens. All the quinolones were highly active against Neisseria gonorrhoeae. A-56619 had the lowest MICs against Chlamydia trachomatis (MIC range, 0.125 to 0.25 micrograms/ml) and Haemophilus ducreyi (MIC for 90% of isolates tested, 0.1 micrograms/ml).

Antimicrobial activity of U-70138F (paldimycin), roxithromycin (RU 965), and ofloxacin (ORF 18489) against Chlamydia trachomatis in cell culture

The MICs of three new antimicrobial agents of different classes, U-70138F, roxithromycin (RU 965), and ofloxacin (ORF 18489), versus Chlamydia trachomatis in McCoy cell cultures were 0.25, 0.8, and 1.0 microgram/ml, respectively. For each test drug, the MIC and MBC were identical or were within 1 dilution of one another. These drugs possessed sufficient activity in cell culture to suggest possible clinical effectiveness.

Failure of norfloxacin to eradicate Chlamydia trachomatis in nongonococcal urethritis

Norfloxacin has some activity in vitro against Chlamydia trachomatis and Ureaplasma urealyticum, although not at levels attainable in serum. In this study, norfloxacin was administered (400 mg orally twice daily for 10 days) to men with acute nongonococcal urethritis. Of 25 men from whom C. trachomatis was initially isolated, 21 had the organism reisolated at the first follow-up visit posttreatment, and there were minimal changes in the number of inclusion-forming units in culture. Ultimately, all but 1 of the 22 men from whom C. trachomatis was initially isolated and who were monitored became clinical failures within 42 +/- 7 days posttreatment. The clinical outcome was significantly better for men from whom U. urealyticum was initially isolated but from whom C. trachomatis was not isolated. Of 27 men, 17 became and stayed culture negative for U. urealyticum at follow-ups, and clinically, 15 no longer had nongonococcal urethritis. Of these 15, all 12 monitored until at least 42 +/- 7 days posttreatment remained improved. Of 26 men from whom neither C. trachomatis nor U. urealyticum was initially isolated, 18 improved and all 15 who were monitored until at least 42 +/- 7 days posttreatment remained improved. Thus, although norfloxacin attains high levels in urine and has good tissue penetration, it had essentially no activity against chlamydial urethritis in men. It had better, but incomplete, activity against U. urealyticum. For quinolones to show promise in vivo against C. trachomatis, either the MICs will need to be much lower or the levels attained in serum will have to be much higher.

Antichlamydial activity of ofloxacin

The in vitro activity of ofloxacin, a new pyridone-carboxylic acid, against 11 strains of Chlamydia trachomatis and six strains of Chlamydia psittaci was determined. All test strains of both species were inhibited by 0.39 micrograms of ofloxacin per ml. The antichlamydial activity of ofloxacin was comparable to that of doxycycline and four- to eightfold less than that of minocycline. The results of this susceptibility test, coupled with those of previous pharmacokinetic analyses of ofloxacin, warrant further evaluation of its clinical usefulness against chlamydial infections.