Gentamicin Susceptibility among a Sample of Multidrug-Resistant Neisseria gonorrhoeae Isolates in India

Abstract

bAntimicrobial susceptibility testing of 258 Neisseria gonorrhoeae isolates by Etest determined that 60.1% were multidrug resistant (MDR), while 5% of the strains had decreased susceptibility to currently recommended extended-spectrum cephalosporins (ESCs). Among these, 84.5% of MDR strains and 76.9% of strains that had decreased susceptibility to ESCs were susceptible to gentamicin. No MDR isolate was resistant to gentamicin. These in vitro results suggest that gentamicin might be an effective treatment option for the MDR strains and in dual therapy for gonorrhea. However, further research regarding the clinical treatment outcomes is essential. N eisseria gonorrhoeae clinical isolates resistant to extendedspectrum cephalosporins (ESCs), the last remaining options for empirical therapy, and most other antimicrobials have been reported worldwide in recent years (1-4). Organizations such as the World Health Organization (WHO), the U.S. Centers for Disease Control and Prevention (CDC), and the European Centre for Disease Prevention and Control (ECDC) are considering infections caused by multidrug-resistant (MDR) and extensively drugresistant (XDR) N. gonorrhoeae major public health problems (5-7). With the increasing prevalence of drug resistance, there is an urgent need for new and effective treatment options. Gentamicin has been used for the past 2 decades in the management of gonorrhea in Malawi (8, 9). Gentamicin has been considered an option for the treatment of infections due to the MDR and XDR strains and for future treatment of gonorrhea particularly in dual therapy in other geographic regions (10-12).Earlier studies focused on the in vitro susceptibility of N. gonorrhoeae to gentamicin (8,(13)(14)(15)(16)(17). Some of these studies were on a limited number of isolates (13,17). To the best of our knowledge, no study has analyzed the in vitro susceptibility of gentamicin against MDR strains. Therefore, this study was aimed at determining the (i) trend of in vitro susceptibility of N. gonorrhoeae isolates to gentamicin during 2010 to 2015, (ii) status of gentamicin susceptibility for MDR strains and strains with decreased susceptibility to ESCs, and (iii) profile of gentamicin-less-susceptible (LS) strains for eight other antimicrobials recommended currently and in the past for treatment of gonorrhea.A total of 258 N. gonorrhoeae isolates obtained from consecutive patients attending a sexually transmitted disease (STD) clinic from August 2010 to December 2015 were identified on the basis of colony morphology, Gram staining, and oxidase, superoxol, and carbohydrate utilization tests (18). Susceptibility testing for gentamicin and other antimicrobials, such as ESCs (ceftriaxone, cefpodoxime, cefixime), penicillin, tetracycline, ciprofloxacin, spectinomycin, and azithromycin, was performed using the Etest strip per manufacturer instructions (bioMérieux SA, France) on GC agar (Becton, Dickinson and Company [BD], Sparks, MD) containing 1% vitamin growth supplement (HiMedia, India) or Isovitalex (BD). Susceptibilit...

<p>Gentamicin susceptibility of <em>Neisseria gonorrhoeae</em> isolates from 7 provinces in China</p>

“…These results are consistent with our surveillance data from 2013 to 2016 in China,8 highlighting the importance of antimicrobial susceptibility surveillance and implications for future gonococcal treatment options. None of the isolates resistant to azithromycin or ceftriaxone were resistant to gentamicin, and we found no relationships between gentamicin MICs and susceptibility profiles of other antimicrobials, which is in tune with a previous study in India 22. Relevant mutations in 23S rRNA, penicillin-binding protein 2 or efflux pump genes6 causing the resistance of azithromycin or ceftriaxone may play no role in forming resistance in gentamicin.…”

In vitro efficacy of 21 dual antimicrobial combinations comprising novel and currently recommended combinations for treatment of drug resistant gonorrhoea in future era

“…Gentamicin is being used in Malawi for more than 20 years for treatment of gonorrhea and it had high in vitro efficacy against MDR stains in a recent study [ 19 , 29 ]. Gentamicin is currently recommended by the WHO in combination with azithromycin in cases of treatment failure [ 10 ].…”

“…During the study period of March 2013 to July 2017, a total of 138 consecutive N . gonorrhoeae isolates were obtained using standard procedures for isolation and identification [ 8 , 19 ]. Written informed consent was taken from the participants.…”

“…gonorrhoeae isolates was determined for penicillin, tetracycline, ciprofloxacin, cefixime, ceftriaxone, spectinomycin, azithromycin, gentamicin, moxifloxacin and ertapenem by the Etest method using the manufacturer’s (bioMerieux SA, 69280 Marcy I’Etoile, France)) instructions [ 20 , 21 ]. Latest interpretive criteria were used for characterisation of strains as susceptible, less susceptible, resistant, MDR and XDR [ 3 , 8 , 15 , 19 , 22 ].…”

“…Every tenth clinical isolate and two quality assurance strains were tested in duplicate for all the antibiotics to check the reproducibility of the testing method. The quality control of the MIC testing was ensured by using the WHO reference strains namely WHO C, WHO F-P and ATCC 49226 for internal quality control and by participating in EQAS every year conducted by WHO Collaborating Centre for STD and HIV, Sydney, Australia [ 19 ].…”