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Journal of Antimicrobial Chemotherapy (2001) 48, 141–156
Correspondence
Emergence of TetM-mediated tetracycline
ductive Health is situated in the rural district of Hlabisa in resistance in rural South Africa
KwaZuluNatal. A direct spinoff of this centre has been theestablishment of an STD clinic for the area. During STD J Antimicrob Chemother 2001; 48: 142–143
prevalence and antimicrobial surveillance studies at thisclinic in 1999, high-level resistance to tetracycline was observed. This study was therefore carried out to deter- mine whether this was TetM mediated, and which variantof the gene was involved Department of Medical Microbiology and Africa Urethral and cervical specimens were collected from Centre for Population Studies and Reproductive patients presenting with genital discharge to the Kwam- Health, School of Infection, Nelson R. Mandela sane STD clinic, in the rural Hlabisa district, KwaZulu- School of Medicine, University of Natal, Natal, between March and December 1999. These Private Bag 7, Congella, 4013 Durban, South Africa specimens were inoculated on to New York City agarplates for the isolation of N. gonorrhoeae. MICs of tetra- *Corresponding author. Tel: +27-31-2604395; cycline were determined using the agar dilution method Fax: +27-31-2604431; E-mail: sturm@nu.ac.za and breakpoint criteria as defined by the NCCLS.5 Selection of potential tetracycline-resistant N. gonor- rhoeae strains was performed by screening for growth on GC agar (supplemented with 1% yeast autolysate and 5% Sexually transmitted infections (STIs) caused by antibiotic- lysed horse blood) containing 10 mg/L tetracycline.
resistant Neisseria gonorrhoeae are a major therapeutic PCR detection and characterization of the tetM gene was problem in many parts of the world. Effective therapy performed on strains of N. gonorrhoeae that grew on the against this pathogen has barely stayed ahead of the acqui- tetracycline-containing plate, by means of a one-step PCR.6 sition of resistance mechanisms and studies continue to PCR products were electrophoresed in a 1% agarose gel document the increase in antimicrobial resistance of N. containing ethidium bromide and visualized by UV fluores- gonorrhoeae to a variety of antibiotics.1,2 The high prevalence of mixed infections, compounded Two-hundred and four strains of N. gonorrhoeae were by the imprecision of an aetiological diagnosis in develop- collected during the study period. One-hundred and thirty- ing countries, underscores the feasibilty of the syndromic six strains (67%) had MICs у 16 mg/L of tetracycline. All approach in the management of STIs. In 1995, South Africa these strains grew on the 10 mg/L tetracycline screening implemented a modified version of the WHO’s syndromic plate and were found to carry the American variant of the management protocol for the treatment of STIs. Doxy- tetM gene, as revealed by the production of a 778 bp PCR cycline is the recommended drug for the treatment of product. The Dutch tetM gene was not found among these Chlamydia trachomatis. However, since the differentiation between gonorrhoea and chlamydial infection is not made, In addition to the use of doxycycline as part of syndromic patients with gonorrhoea are exposed to doxycycline as management, tetracycline derivatives, being relatively part of the syndromic management of genital discharge.
cheap, are widely used for the empirical treatment of respir- In Southern Africa, plasmid-mediated high-level resist- atory and skin and soft tissue infections (P. Moodley et al., ance to tetracycline of N. gonorrhoeae (MIC у 16 mg/L) unpublished results).6 The emergence of TetM-mediated was first described in 1995 among 11 isolates obtained from tetracycline resistance in this area was sudden and is medi- Namibia and Botswana.3 These isolates all carried the ated by a single variant of the tetM gene. Whether this is a American type of tetM gene. This was followed by a report result of the spread of a single strain or by transfer of the from Bloemfontein, South Africa, where the prevalence resistance plasmid within the gonococcal population needs was reported to have increased from 2% (3/145) in 1994 further investigation.
to 18.5% (12/65) in 1995.4 The resistance patterns of thisorganism vary geographically and the presence of high-level tetracycline-resistant organisms has not been described Acknowledgement
The Africa Centre for Population Studies and Repro- This work is financially supported by the Wellcome Trust.
2001 The British Society for Antimicrobial Chemotherapy Correspondence
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