World-wide distribution of high level tetracycline-resistant Neisseria gonorrhoeae

Plasmid mediated penicillin and tetracycline resistance among Neisseria gonorrhoeae isolates from Kenya

BACKGROUND

Treatment of gonorrhea is complicated by the development of antimicrobial resistance in Neisseria gonorrhoeae (GC) to the antibiotics recommended for treatment. Knowledge on types of plasmids and the antibiotic resistance genes they harbor is useful in monitoring the emergence and spread of bacterial antibiotic resistance. In Kenya, studies on gonococcal antimicrobial resistance are few and data on plasmid mediated drug resistance is limited. The present study characterizes plasmid mediated resistance in N. gonorrhoeae isolates recovered from Kenya between 2013 and 2018.

METHODS

DNA was extracted from 36 sub-cultured GC isolates exhibiting varying drug resistance profiles. Whole genome sequencing was done on Illumina MiSeq platform and reads assembled de-novo using CLC Genomics Workbench. Genome annotation was performed using Rapid Annotation Subsystem Technology. Comparisons in identified antimicrobial resistance determinants were done using Bioedit sequence alignment editor.

RESULTS

Twenty-four (66.7%) isolates had both β-lactamase (TEM) and TetM encoding plasmids. 8.3% of the isolates lacked both TEM and TetM plasmids and had intermediate to susceptible penicillin and tetracycline MICs. Twenty-six (72%) isolates harbored TEM encoding plasmids. 25 of the TEM plasmids were of African type while one was an Asian type. Of the 36 isolates, 31 (86.1%) had TetM encoding plasmids, 30 of which harbored American TetM, whereas 1 carried a Dutch TetM. All analyzed isolates had non-mosaic penA alleles. All the isolates expressing TetM were tetracycline resistant (MIC> 1 mg/L) and had increased doxycycline MICs (up to 96 mg/L). All the isolates had S10 ribosomal protein V57M amino acid substitution associated with tetracycline resistance. No relation was observed between PenB and MtrR alterations and penicillin and tetracycline MICs.

CONCLUSION

High-level gonococcal penicillin and tetracycline resistance in the sampled Kenyan regions was found to be mediated by plasmid borne blaTEM and tetM genes. While the African TEM plasmid, TEM1 and American TetM are the dominant genotypes, Asian TEM plasmid, a new TEM239 and Dutch TetM have emerged in the regions.

The prevalence and epidemiology of plasmid-mediated penicillin and tetracycline resistance among Neisseria gonorrhoeae isolates in Guangzhou, China, 2002-2012

Background

Gonococcal antimicrobial resistance is a global problem. Different resistance plasmids have emerged and spread among the isolates of Neisseria gonorrhoeae worldwide and in China. We conducted this study to monitor the plasmid-mediated penicillin and tetracycline resistance among N. gonorrhoeae isolates in Guangzhou from 2002 to 2012.

Methods

Consecutive isolates of N. gonorrhoeae were collected from outpatients with gonorrhea attending the STD clinic in Guangdong Provincial Centre for Skin Diseases and STIs Control and Prevention. Penicillinase-producing N. gonorrhoeae (PPNG) isolates were analyzed by the paper acidometric method. Plasmid-mediated resistance to tetracycline in N. gonorrhoeae (TRNG) isolates was screened by the agar plate dilution method. Plasmid types were determined for TRNG and PPNG isolates using polymerase chain reaction (PCR). Minimum inhibitory concentrations (MICs) to penicillin and tetracycline were detected by the agar plate dilution.

Results

Of 1378 consecutive N. gonorrhoeae isolates, 429 PPNG and 639 TRNG isolates were identified. The prevalence of PPNG, TRNG, and PPNG/TRNG increased from 18.3 to 47.1 % (χ² = 31.57, p < 0.001), from 29.4 to 52.1 % (χ² = 16.28, p < 0.001) and from 10.0 to 26.2 % (χ² = 10.46, p < 0.001) between 2002 and 2012, respectively. Genotyping of plasmids among PPNGs showed that the majority (93.7 %) of the isolates were the Asian type plasmids, while the African type plasmid emerged in 2008 and rapidly increased to 14.0 % in 2012 (χ² = 25.03, p < 0.001). For TRNGs, all 639 isolates carried the Dutch type plasmid. MICs of penicillin G and tetracycline persisted at high levels and the MIC_90s were 32-fold higher than the resistant cutoff point over 11 years. The prevalence rates of penicillin- and tetracycline-resistant N. gonorrhoeae varied from 90.9 to 91.1 % and from 88.3 to 89.3 % during 2002 to 2012, respectively.

Conclusions

Resistance to penicillin and tetracycline among N. gonorrhoeae isolates remained at high levels in Guangzhou. The Asian type PPNG continued to spread and Dutch type TRNG was still the dominant strain. The African type PPNG has emerged and is spreading rapidly.

Molecular epidemiology of tetM genes in Neisseria gonorrhoeae

OBJECTIVE

To examine the epidemiology of the tetM gene in Neisseria gonorrhoeae strains with high level resistance to tetracycline (TRNG) using a polymerase chain reaction (PCR) assay.

METHODS

A single tube PCR was developed which distinguishes between the American and Dutch variants of the tetM gene. Between 1988 and 1995, 518 strains of TRNG (tetracycline MIC > 8.mg/l) were referred to the Gonococcus Reference Unit by other laboratories or isolated from routine swabs taken at local clinics. The strains were analysed for plasmid content, auxotype, serovar, and the tetM gene type. Travel details of the patients were determined by a questionnaire.

RESULTS

A PCR product was obtained from all TRNG examined. 387 TRNG strains produced a 778 bp PCR product (American type tetM) and 131 produced a 443 by PCR product (Dutch type tetM). Infections acquired in the United Kingdom contributed 57% of the TRNG strains included in this study; 82% of these carried the American type of tetM. The number of UK acquired TRNG received by the GRU increased each year except 1993--from four strains received in 1990 to 92 in 1995. After the United Kingdom, Caribbean and African countries contributed most strains, with 56 and 60 TRNG acquired in each area respectively. All strains originating in Africa, except one from South Africa, contained the American type tetM. Infections caught in Nigeria and Kenya contributed most strains (15 and 14 respectively). The TRNG originating from Caribbean countries comprised 36% Dutch tetM type. Infections caught in Jamaica accounted for 82% of the Caribbean strains. All 35 TRNG strains originating in the Far East contained the Dutch type tetM. 25 of the Far East strains were also penicillinase producing (PPNG). Infections originating in Indonesia accounted for 49% of the Far East strains but these belonged to 12 different auxotype/serovar combinations. A geographical variation in the type of penicillinase coding plasmids found in PPNG/TRNG was also detected.

CONCLUSIONS

These data suggest that the Dutch type tetM may have originated in the Far East and the American type in the African continent. Subsequent spread has resulted in a heterogeneous distribution of TRNG types in other parts of the world. At completion of the survey the numbers of TRNG imported each year from the major overseas sources had reached a plateau while UK contracted TRNG continued to rise providing evidence for the establishment of endemic TRNG strains in the United Kingdom.