Tolerance to Ceftriaxone in Neisseria gonorrhoeae: Rapid Induction in WHO P Reference Strain and Detection in Clinical Isolates

Abstract

In addition to antimicrobial resistance, bacteria contain other mechanisms to survive antibiotic exposure such as tolerance, defined as the ability to slow metabolism by the extension of the lag phase without altering antimicrobial susceptibility. In a number of bacterial species, tolerance has been associated with treatment failure and infection chronicity and is found to precede and facilitate antimicrobial resistance. It is unknown if tolerance can be induced in Neisseria gonorrhoeae. In this study, we determined if tolerance to ceftriaxone (CRO) can be induced in N. gonorrhoeae and detected in clinical isolates. To induce tolerance, WHO P N. gonorrhoeae reference strain samples were grown under daily 3 h intermittent CRO exposure (10× the MIC), partitioned by overnight growth in GC broth. This cyclic exposure was performed for 7 consecutive days in sextuplicate, with two control cultures to which GC medium without antibiotics was added. To detect tolerance and assess CRO susceptibility, modified Tolerance Disc (TD) and Epsilometer tests were performed on isolates after each CRO exposure cycle. Additionally, this experiment was carried out on 18 clinical N. gonorrhoeae isolates. Tolerance was first detected after two CRO exposure cycles in five out of six samples. The phenotype differed per cycle with no clear pattern. No tolerance was found in control samples but was detected in 10 out of 18 clinical isolates. The present study is the first to demonstrate the induction of tolerance to CRO in N. gonorrhoeae through antibiotic exposure. In addition, tolerance to CRO was found in clinical samples.

Enolase Is Implicated in the Emergence of Gonococcal Tolerance to Ceftriaxone

“…Previously, we reported that tolerance to CRO can be induced in CRO-susceptible (<0.004 µg/mL) N. gonorrhoeae WHO P reference isolate [ 17 ]. In the current analysis, we describe, for the first time, the mutations associated with emergence of CRO tolerance in N. gonorrhoeae.…”

“…We recently induced tolerance to ceftriaxone (CRO) in N. gonorrhoeae reference isolates (WHO P) [ 17 ]. A highly susceptible CRO reference strain, WHO P with a CRO MIC of 0.004 µg/mL, was used [ 18 ].…”

“…Blue arrow indicates emergent tolerant colonies at Step III. Figure is reproduced with permission from [ 17 ].…”

“…We recently succeeded in inducing tolerance to ceftriaxone (CRO) via intermittent cyclic CRO exposure in N. gonorrhoeae reference isolates (WHO P) [ 17 ]. In the current study, using whole-genome sequencing (WGS), we characterized the mutation profile of these CRO-tolerant phenotypes.…”

Availability of Laboratory Diagnosis of Gonorrhoea and Its Meaning in Case Reporting in Shandong Province, China

“… 11 In addition, tolerance to ceftriaxone was found in clinical samples. 12 However, if the surveillance data cannot interpret the current situation of gonorrhea epidemic, misleading may be inevitable in policy making for gonorrhea prevention and control. Many factors may affect the integrity and accuracy of surveillance data.…”