APMIS 112: 771–84, 2004 Copyright C APMIS 2004 Printed in Denmark . All rights reserved ISSN 0903-4641 Molecular genetic methods for diagnosis and characterisation of Chlamydia trachomatis and Neisseria gonorrhoeae : impact on epidemiological surveillance and interventions HANS FREDLUND, 1,2 LARS FALK, 3 MARGARETHA JURSTRAND 1,2 and MAGNUS UNEMO 1,2 1 Department of Clinical Microbiology, 2 National Reference Laboratory for Pathogenic Neisseria, and 3 Department of Dermatology and Venereology, Örebro University Hospital, Örebro, Sweden Fredlund H, Falk L, Jurstrand M, Unemo M. Molecular genetic methods for diagnosis and character- isation of Chlamydia trachomatis and Neisseria gonorrhoeae: impact on epidemiological surveillance and interventions. APMIS 2004;112:771–84. One of the mainstays in the prevention of Chlamydia trachomatis and Neisseria gonorrhoeae infections is the availability of laboratory diagnostics with high sensitivity and specificity. Assays for diagnosis of C. trachomatis include cell culture and nucleic acid amplification tests (NAATs). The major target sequences for C. trachomatis diagnosis by NAATs are located at the cryptic plasmid and the major target used for characterisation is the omp1 gene. The gold standard for diagnosis of N. gonorrhoeae is culture. However, numerous NAATs for identification of N. gonorrhoeae and a number of molecular genetic methods for characterisation of N. gonorrhoeae have been developed. Probably no routine laboratory can attain as high sensitivity by culturing C. trachomatis or N. gonorrhoeae as by using NAATs. For that reason NAATs can be recommended for diagnosing C. trachomatis, but not as the only diagnostic assay for N. gonorrhoeae, due to lack of antibiotic susceptibility testing and specificity problems, most pronounced for pharyngeal and rectal samples. Genotyping of C. trachomatis or N. gonorrhoeae provides additional information for contact tracing. It is recommended for N. gonorrhoeae, at least in low prevalence geographic areas, but cannot today be recommended for C. trachomatis. This is due to the low genetic variability and hence the limited benefits for partner notification. However, genotyping of C. trachomatis may play an important role under special circum- stances. Key words: Diagnosis; characterisation; molecular genetic methods; C. trachomatis; N. gonorrhoeae. Hans Fredlund, Department of Clinical Microbiology, Örebro University Hospital, SE-701 85 Örebro, Sweden. e-mail: hans.fredlund/orebroll.se Chlamydia trachomatis and Neisseria gon- orrhoeae infections belong to the most frequently encountered sexually transmitted infections worldwide (1). Even though the bacteriological diagnosis was not established until the 19th and 20th centuries, clinical symptoms probably as- sociated with these bacteria are described in the ancient literature (2). The clinical spectrum of genital diseases Invited Review. 771 caused by these two bacteria is quite similar and mainly comprises urethritis in men and ureth- ritis/cervicitis in women. However, no symp- toms or only very slight symptoms such as weak discharge are common, especially in women. Oropharyngeal infections may occur in both sexes, and eye infections, acquired from infected mothers, are described in newborns. Conjuncti- vitis in adults is due to self-inoculation from a genital infection (3, 4). Most complications due to C. trachomatis and/or N. gonorrhoeae infections affect women.