Comparison of single-dose oral grepafloxacin with cefixime for treatment of uncomplicated gonorrhea in men. The STD Study Group

Treatment efficacy for rectal Neisseria gonorrhoeae: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Rectal gonorrhoea is a common sexually transmitted infection with increasing antimicrobial resistance requiring optimization of available treatments.

OBJECTIVES

This systematic review aimed to assess the efficacy of current treatments, previously trialled treatments and new emerging treatments for rectal Neisseria gonorrhoeae (NG).

METHODS

Online bibliographic databases were search from 1 January 1946 to 14 August 2020. All randomized controlled trials (RCTs) with rectal NG data among participants aged 15 years or above and published in English were included. Random effects meta-analyses were used to estimate overall treatment efficacy, defined as microbiological cure. Sub-group analyses included stratifying by diagnostic assay, by dual versus monotherapy, and by currently recommended treatments (e.g. ceftriaxone ± azithromycin) versus previously trialled but not recommended treatments (e.g. amoxicillin) versus emerging treatments (e.g. zoliflodacin). The study protocol was registered on PROSPERO (CRD42020202998).

RESULTS

54 studies including 1813 participants and 44 treatment regimens were identified. The overall summary treatment efficacy for rectal NG was 100.0% (95% CI: 99.9%-100.0%; I2 = 0.0%; P = 0.86). Efficacy estimates for monotherapies (100.0%; 95% CI: 99.88%-100.0%; I2 = 0.00%; P = 0.97) and dual therapies (100.0%; 95% CI: 97.65%-100.0%; I2 = 56.24%; P = 0.03) were similar. Efficacy was highest for current treatments (100.00%; 95% CI: 99.96%-100.00%; I2 = 0.00%; P = 0.98) versus emerging treatments (97.16%; 95% CI: 86.79%-100.00%; I2 = 0.00%; P = 0.84). There were no trials exclusively investigating rectal NG and small sample size was a limitation in most trials.

CONCLUSIONS

Currently recommended treatments containing ceftriaxone, as mono or dual therapy, are effective. Emerging drugs such as zoliflodacin may be potentially useful for rectal NG but further data are needed.

Emergence and spread of Neisseria gonorrhoeae clinical isolates harboring mosaic-like structure of penicillin-binding protein 2 in Central Japan

Of 150 clinical isolates of Neisseria gonorrhoeae recovered in 2001, we examined 55 clinical isolates of N. gonorrhoeae for which cefixime MICs were > or=0.125 microg/ml and randomly selected 15 isolates for which cefixime MICs were < or =0.06 microg/ml for analysis of alterations in the penicillin-binding protein 2 (PBP 2) gene. We found insertion of an extra codon (Asp-345a) in the transpeptidase domain of PBP 2, and this insertion occurred alone or in conjunction with other amino acid substitutions. We also found a mosaic PBP 2 that was composed of fragments of the PBP 2 proteins from Neisseria cinera and Neisseria perflava. This mosaic PBP 2 was significantly associated with decreased susceptibilities to penicillin and cephalosporins, especially oral cephalosporins. For most of the isolates with a mosaic PBP 2, the cefixime MICs were > or =0.5 microg/ml and the cefdinir MICs were > or =1 microg/ml. Analysis of chromosomal DNA restriction patterns by pulsed-field gel electrophoresis revealed that most isolates with the mosaic PBP 2 were genetically similar. The recombination events that generated the mosaic PBP 2 would likely have contributed to the decreased sensitivities to cephalosporins. Isolates with the mosaic PBP 2 appear to threaten the efficacy of the currently recommended regimen with cefixime. The emergence of such strains may be the result of the in vivo generation of clones in which interspecies recombination occurred between the penA genes of N. gonorrhoeae and commensal Neisseria species.

Treatment of uncomplicated gonococcal urethritis by double-dosing of 200 mg cefixime at a 6-h interval

The efficacy of antimicrobial regimens for the treatment of uncomplicated gonococcal urethritis depends partially upon the period of time (therapeutic time) during which the drug concentration in the blood after the concentration peak is greater than four times the minimum inhibitory concentration for 90% of clinical isolates of Neisseria gonorrhoeae (MIC(90)). A therapeutic time of at least 10 h is suggested as an important determinant for elimination of 95% or more of the infection. In this study, therapeutic times for a single 400-mg dose of cefixime at various MIC(90)s were calculated, and pharmacokinetic profiles of double-dosing of 200 mg cefixime at various intervals were simulated. Subsequently, a dosing interval of 6 h was tested in 6 healthy Japanese men, and then 93 Japanese men with gonococcal urethritis were treated with a regimen of two 200-mg doses of cefixime given at a 6-h interval. For a single dose of 400 mg cefixime, therapeutic times were calculated to be 12.8, 9.1, 5.4, and 1.7 h for MIC(90)s of 0.06, 0.125, 0.25, and 0.5 microg/ml, respectively. In the simulation study of double-dosing of 200 mg cefixime at a 6-h interval, the therapeutic times for the MIC(90)s of < or =0.125 microg/ml were longer than 10 h. Of the 93 patients, 68 were evaluated for microbiological outcome, and N. gonorrhoeae was eradicated in 60 (88.2%). The MIC(90) of cefixime for the 61 isolates tested was 0.125 microg/ml. All strains with MICs of < or =0.06 microg/ml were eradicated, whereas 8 of 16 strains with MICs of > or =0.125 microg/ml persisted after treatment. This regimen would not be effective against infection by strains exhibiting cefixime MIC(90)s of > or =0.125 microg/ml. For such strains, a different regimen with a higher dose of cefixime would be required.

Single-dose gatifloxacin compared with ofloxacin for the treatment of uncomplicated gonorrhea: a randomized, double-blind, multicenter trial

BACKGROUND

Treatment of gonorrhea is complicated by widespread resistance of Neisseria gonorrhoeae to antimicrobial agents of choice, including decreased susceptibility to ciprofloxacin.

GOAL

To demonstrate the efficacy and safety of gatifloxacin, a novel 8-methoxy fluoroquinolone antibiotic, compared with ofloxacin in treating patients with uncomplicated gonococcal infection.

STUDY DESIGN

In a double-blind, randomized (2:2:1), controlled trial, 340 men and 388 women with uncomplicated gonorrhea who were 16 years or older received a single oral dose of gatifloxacin (400 mg or 600 mg) or ofloxacin (400 mg). Primary analysis of efficacy was based on bacteriologic eradication from sites of infection. Secondary analyses examined clinical response and adverse event profiles.

RESULTS

Bacteriologic eradication rates for gatifloxacin in evaluable men with urethral gonorrhea were 99% (400 mg) and 100% (600 mg) versus 100% for ofloxacin (n = 117, 122, and 55, respectively; P = ns). Eradication rates in evaluable women with endocervical gonorrhea were 99% for both 400 mg and 600 mg gatifloxacin versus 100% for ofloxacin (n = 101, 104, and 55, respectively; P = ns). Eradication rates were 100% for both rectal (n = 43) and pharyngeal (n = 31) infection across all treatment groups. All three drug regimens were well tolerated and exhibited similar clinical response profiles.

CONCLUSION

Gatifloxacin is safe and effective as a single 400-mg or 600-mg dose for the treatment of uncomplicated gonorrhea. Similar efficacy rates were observed with the 400-mg and 600-mg doses. A single 400-mg dose can be recommended for treatment of uncomplicated gonorrhea.

Concurrent gonococcal and chlamydial infection: how best to treat

Clinicians treating concurrent gonococcal and chlamydial infections have a variety of drugs to choose from. Neisseria gonorrhoeae is adept at developing resistance and the choice of antibiotic must be dictated to some extent by the patterns of resistance in the locality of the clinician. In contrast, resistance of Chlamydia trachomatis to some classes of drugs has been shown in vitro but does not appear to be clinically important at present. The success of treatment depends on patient compliance with the drug administration schedule. With these organisms, which can be carried asymptomatically, many patients are unlikely to comply with courses of antibiotics. Although single-dose therapy with azithromycin is available and established for chlamydial genital infection, it is more expensive and difficult to justify in a cash limited Healthcare system, and its efficacy for treating concurrent gonococcal infection requires further study. In patients where compliance is likely to be of concern, its use may be justified. Another major deterrent for completing antibiotic courses is the adverse effect profile. Most of the available drugs cause only minor adverse effects, in particular gastrointestinal. Ofloxacin has a better profile than doxycycline but is considerably more expensive. Newer fluoroquinolones, found to be effective in vitro, are being assessed in clinical studies. However, more evidence is required before recommending these over the tried and tested therapies.

Quinolones in sexually transmitted diseases: state of the art

Progress in the development of fluoroquinolones for the treatment of sexually transmitted diseases has been slow. New compounds have appeared with good in vitro activity against the gonococcus, Chlamydia trachomatis and the genital mycoplasmas. However, there have been increasing reports of clinically relevant resistance by the gonococcus, and chlamydial and mycoplasmal resistance in vitro has been described. Formally reported treatment studies have not been forthcoming, despite an emerging role for the newer fluoroquinolones in the ambulatory treatment of pelvic inflammatory disease.

Potential interactions of the extended-spectrum fluoroquinolones with the CNS

The new generation fluoroquinolones -- sparfloxacin, levofloxacin, grepafloxacin and trovafloxacin -- have been designed to respond to the clinical need for extended antimicrobial cover in the face of increasing global microbial resistance. Their main focus is in the treatment of respiratory infections, particularly those acquired in the community. CNS adverse effects, such as dizziness and headache, are known to occur relatively commonly with some fluoroquinolones and are not, in general, well tolerated by patients. The structural component of the fluoroquinolone molecule believed to be responsible for improved gram-positive activity is also believed to be implicated in the production of CNS adverse effects, including those arising from drug interactions with theophylline and NSAIDs. Inhibition of brain gamma-aminobutyric acid (GABA) receptor binding appears to be a strong indicator of CNS activity, though N-methyl-D-aspartate receptor binding has also been implicated. In accordance with the results of these predictive studies, clinical trials have found sparfloxacin, levofloxacin and grepafloxacin to be associated with a low incidence of CNS events. Trovafloxacin has been found to be associated with a higher incidence of CNS events (particularly lightheadedness and dizziness) than the other 3 agents. Ongoing and future clinical studies will help to define the usefulness of the predictive models, as well as reveal the full CNS adverse event profile of these and other investigational fluoroquinolones.

The new fluoroquinolones: A critical review

OBJECTIVE

This paper reviews the literature available on the new fluoroquinolones - clinafloxacin, gatifloxacin, grepafloxacin, levofloxacin, moxifloxacin, sparfloxacin and trovafloxacin - to compare these agents with each other and contrast them with ciprofloxacin, an older fluoroquinolone.

DATA SELECTION

Published papers used were obtained by searching MEDLINE for articles published between 1994 and 1998, inclusive. References of published papers were also obtained and reviewed. Abstracts from scientific proceedings were reviewed.

DATA EXTRACTION

Due to the limited data available on several of the agents, criteria for study inclusion in the in vitro, pharmacokinetics and in vivo sections were not restrictive.

DATA SYNTHESIS

The new fluoroquinolones offer excellent Gram-negative bacillary activity and improved Gram-positive activity (eg, against Streptococcus pneumoniae and Staphylococcus aureus) over ciprofloxacin. Clinafloxacin, gatifloxacin, moxifloxacin, sparfloxacin and trovafloxacin display improved activity against anaerobes (eg, Bacteriodes fragilis). All of the new fluoroquinolones have a longer serum half-life than ciprofloxacin (allowing for once daily dosing), and several are eliminated predominantly by nonrenal means. No clinical trials are available comparing the new fluoroquinolones with each other. Clinical trials comparing the new fluoroquinolones with standard therapy have demonstrated good efficacy in a variety of infections. Their adverse effect profile is similar to that of ciprofloxacin. Clinafloxacin and sparfloxacin cause a high incidence of phototoxicity (1.5% to 14% and 2% to 11.7%, respectively), grepafloxacin causes a high incidence of taste perversion (9% to 17%) and trovafloxacin causes a high incidence of dizziness (11%). They all interact with metal ion-containing drugs (eg, antacids), and clinafloxacin and grepafloxacin interact with theophylline. The new fluoroquinolones are expensive; however, their use may result in savings in situations where, because of their potent and broad spectrum of activity, they can be used orally in place of intravenous antibiotics.

CONCLUSIONS

The new fluoroquinolones offer advantages over ciprofloxacin in terms of improved in vitro activity and pharmacokinetics. Whether these advantages translate into improved clinical outcomes is presently unknown. The new fluoroquinolones have the potential to emerge as important therapeutic agents in the treatment of respiratory tract and genitourinary tract infections.

Antimicrobial resistance in Neisseria gonorrhoeae

Despite a declining incidence of gonorrhea in much of the industrialized world, antimicrobial resistance continues to present a challenge to the treatment of gonococcal infections. Although no clinically significant resistance to the broad-spectrum cephalosporins has been identified, fluoroquinolone-resistant gonococcal strains are now prevalent in Australia and much of the Far East. Ongoing surveillance for antimicrobial resistance is crucial to obtain the information needed to choose effective empiric therapies for gonorrhea.

Grepafloxacin

Grepafloxacin (OPC-17116) is a new once-daily fluoroquinolone antimicrobial agent which appears to have high tissue penetration and the wide spectrum of antimicrobial activity typical of this class of agents, but with improved activity against Gram-positive organisms, notably Streptococcus pneumoniae. The in vitro activity of grepafloxacin was similar to or slightly lower than that of ciprofloxacin against Enterobacteriaceae but better than that of ciprofloxacin against most Gram-positive organisms. In particular, grepafloxacin showed good activity against pathogens implicated in community-acquired pneumonia, with 4-fold higher potency than ciprofloxacin against S. pneumoniae, including penicillin-resistant strains. In animal studies, grepafloxacin did not induce convulsions when administered at high doses in conjunction with nonsteroidal anti-inflammatory agents. Grepafloxacin has a weak propensity for causing phototoxicity, similar to that of ciprofloxacin. In comparative clinical trials, grepafloxacin demonstrated similar efficacy to amoxicillin in community-acquired pneumonia, ofloxacin in pneumonia and chronic respiratory tract infection, and cefixime in uncomplicated gonococcal urethritis and gonococcal cervicitis. Grepafloxacin has also shown clinical efficacy in preliminary studies in patients with chlamydial endocervical infection or bacillary dysentery.