Abstract
To survey the circulating strains of Mycobacterium tuberculosis in Turkey, all clinical isolates (381 patients) recovered in laboratories in six cities during one-month periods were collected and typed by IS6110-DNA fingerprinting and spoligotyping. Drug susceptibilities were also determined. About 23% of the isolates were resistant to one or more drugs and about 4% were multidrug resistant (i.e., resistant to at least isoniazid and rifampin). IS6110-DNA fingerprints and spoligotypes were obtained from 368 and 374 strains, respectively. Of the 374 isolates spoligotyped, 87 (23%) displayed unique spoligotypes and 287 (77%) displayed one of 34 spoligotypes (2-77 isolates per pattern). The clustered spoligotypes included ones that matched spoligotypes of the T (37% of isolates), LAM (20%), Haarlem (8%) and Beijing (2%) families. Of the 368 isolates IS6110-typed, 232 (63%) displayed unique IS6110-fingerprint patterns and 136 (37%) displayed one of 35 patterns (2-34 isolates per pattern). When IS6110 fingerprinting and spoligotyping information were combined for the 381 isolates tested, 273 isolates (72%) displayed unique genotypes and 108 isolates (28%) displayed one of 34 genotypes (2-24 isolates per genotype). In summary, many different strains are circulating in Turkey with no single strain appearing to be dominant as has been observed in other areas of the world with high tuberculosis incidence.
Highlights
Tuberculosis remains one of the most significant infectious causes of death, annually causing ∼2 million deaths worldwide[1]
Molecular typing of M. tuberculosis isolates can be useful in elucidating the natural history of the tuberculosis epidemic and evaluating tuberculosis control efforts
Molecular characterization of M. tuberculosis strains has been used for more than a decade to study the epidemiology of tuberculosis and has proven to be a useful tool in many public health settings[22]
Summary
Tuberculosis remains one of the most significant infectious causes of death, annually causing ∼2 million deaths worldwide[1]. The molecular clock of IS6110 pattern variation is slow enough to be useful for outbreak investigation and yet fast enough for this to be the most discriminatory of the available typing techniques[8]. Spacer oligonucleotide typing (spoligotyping) is a secondary typing method that is useful for isolates with low-copy numbers of IS6110[10,11,12,13,14]. When molecular genotyping is applied at the population level, the clustering of isolates can provide important clues about the patterns and dynamics of transmission in the population[16]. We determined the relative frequency of M. tuberculosis strains in specific geographic areas to better define the spectrum of circulating strains in Turkey and provide clues as to transmission dynamics. All clinical isolates (381 patients) recovered from laboratories in six cities during one-month periods were collected and genotyped using a combination of IS6110-DNA fingerprinting and direct-repeat-based spoligotyping
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