The Use of Gentamicin for Treatment of Urogenital and Extragenital Gonorrhea: A Systematic Review of Efficacy Data

In vitro susceptibility of Neisseria gonorrhoeae to netilmicin and etimicin in comparison to gentamicin and other aminoglycosides

PURPOSE

Single doses of gentamicin have demonstrated clinical efficacy in the treatment of urogenital gonorrhea, but lower cure rates for oropharyngeal and anorectal gonorrhea. Formulations selectively enriched in specific gentamicin C congeners have been proposed as a less toxic alternative to gentamicin, potentially permitting higher dosing to result in increased plasma exposures at the extragenital sites of infection. The purpose of the present study was to compare the antibacterial activity of individual gentamicin C congeners against Neisseria gonorrhoeae to that of other aminoglycoside antibiotics.

METHODS

Antimicrobial susceptibility of three N. gonorrhoeae reference strains and 152 clinical isolates was assessed using standard disk diffusion, agar dilution, and epsilometer tests.

RESULTS

Gentamicin C1, C2, C1a, and C2a demonstrated similar activity against N. gonorrhoeae. Interestingly, susceptibility to the 1-N-ethylated aminoglycosides etimicin and netilmicin was significantly higher than the susceptibility to their parent compounds gentamicin C1a and sisomicin, and to any other of the 25 aminoglycosides assessed in this study. Propylamycin, a 4'-propylated paromomycin analogue, was significantly more active against N. gonorrhoeae than its parent compound, too.

CONCLUSION

Selectively enriched gentamicin formulations hold promise for a less toxic but equally efficacious alternative to gentamicin. Our study warrants additional consideration of the clinically established netilmicin and etimicin for treatment of genital and perhaps extragenital gonorrhea. Additional studies are required to elucidate the mechanism behind the advantage of alkylated aminoglycosides.

Thiostrepton, a resurging drug inhibiting the stringent response to counteract antibiotic-resistance and expression of virulence determinants in Neisseria gonorrhoeae

Due to the increased resistance to all available antibiotics and the lack of vaccines, Neisseria gonorrhoeae (the gonococcus) poses an urgent threat. Although the mechanisms of virulence and antibiotic resistance have been largely investigated in this bacterium, very few studies have addressed the stringent response (SR) that in pathogenic bacteria controls the expression of genes involved in host-pathogen interaction and tolerance and persistence toward antibiotics. In this study, the results of the transcriptome analysis of a clinical isolate of N. gonorrhoeae, after induction of the SR by serine hydroxamate, provided us with an accurate list of genes that are transcriptionally modulated during the SR. The list includes genes associated with metabolism, cellular machine functions, host-pathogen interaction, genome plasticity, and antibiotic tolerance and persistence. Moreover, we found that the artificial induction of the SR in N. gonorrhoeae by serine hydroxamate is prevented by thiostrepton, a thiopeptide antibiotic that is known to interact with ribosomal protein L11, thereby inhibiting functions of EF-Tu and EF-G, and binding of pppGpp synthase I (RelA) to ribosome upon entry of uncharged tRNA. We found that N. gonorrhoeae is highly sensitive to thiostrepton under in vitro conditions, and that thiostrepton, in contrast to other antibiotics, does not induce tolerance or persistence. Finally, we observed that thiostrepton attenuated the expression of key genes involved in the host-pathogen interaction. These properties make thiostrepton a good drug candidate for dampening bacterial virulence and preventing antibiotic tolerance and persistence. The ongoing challenge is to increase the bioavailability of thiostrepton through the use of chemistry and nanotechnology.

Safety of Single-Dose Oral Cefixime, Intramuscular Ceftriaxone, or Intramuscular Gentamicin for the Treatment of Gonorrhea: A Systematic Review and Meta-analysis

OBJECTIVE

To compare the incidence and types of adverse effects between 3 recommended treatment options for gonorrhea and to compare the incidence of injection site pain between single-dose intramuscular ceftriaxone and gentamicin.

DATA SOURCES

A keyword search of MEDLINE (1966 to September 2020), EMBASE (1947 to September 2020), and International Pharmaceutical Abstracts (1970 to September 2020) was conducted. The electronic search was supplemented with manual screening of references.

STUDY SELECTION AND DATA EXTRACTION

Comparator studies reporting adverse effect outcomes of treatment with cefixime, ceftriaxone, or gentamicin for gonorrhea in humans were included. Data extracted included study year, authors, aim, setting, population, dosing protocols, and outcome results.

DATA SYNTHESIS

A total of 298 articles were identified, of which 6 met inclusion criteria. Two randomized controlled trials compared ceftriaxone and gentamicin. Four randomized controlled trials compared cefixime and ceftriaxone. No differences were noted for the occurrence of at least 1 adverse effect between gentamicin and ceftriaxone (odds ratio [OR] = 0.81; 95% CI = 0.56-1.18) or between cefixime and ceftriaxone (OR = 1.11; 95% CI = 0.21-5.93). Injection site pain (ceftriaxone and gentamicin) and other adverse effects (all drugs) were common but occurred at similar rates between groups.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

Results of this review show a lack of signal for safety concerns with gentamicin-based regimens for the treatment of gonorrhea. Future research should investigate patient acceptability, especially for intramuscular injections.

CONCLUSIONS

The use of single-dose cefixime, ceftriaxone, and gentamicin-based regimens for treatment of gonorrhea appears to be safe and acceptable for use in practice.