Zoonotic Chlamydiaceae species associated with trachoma, Nepal - PubMed (original) (raw)

Zoonotic Chlamydiaceae species associated with trachoma, Nepal

Deborah Dean et al. Emerg Infect Dis. 2013 Dec.

Abstract

Trachoma is the leading cause of preventable blindness. Commercial assays do not discriminate among all Chlamydiaceae species that might be involved in trachoma. We investigated whether a commercial Micro-ArrayTube could discriminate Chlamydiaceae species in DNA extracted directly from conjunctival samples from 101 trachoma patients in Nepal. To evaluate organism viability, we extracted RNA, reverse transcribed it, and subjected it to quantitative real-time PCR. We found that 71 (70.3%) villagers were infected. ArrayTube sensitivity was 91.7% and specificity was 100% compared with that of real-time PCR. Concordance between genotypes detected by microarray and ompA genotyping was 100%. Species distribution included 54 (76%) single infections with Chlamydia trachomatis, C. psittaci, C. suis, or C. pecorum, and 17 (24%) mixed infections that includied C. pneumoniae. Ocular infections were caused by 5 Chlamydiaceae species. Additional studies of trachoma pathogenesis involving Chlamydiaceae species other than C. trachomatis and their zoonotic origins are needed.

Keywords: Chlamydiaceae; Nepal; bacteria; microarray; species and strain typing; trachoma; zoonoses; zoonotic transmission.

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Figures

Figure 1

Figure 1

Chlamydiaceae infections among 101 villagers residing in a trachoma-endemic region of southwestern Nepal identified by the ArrayTube (Alere Technologies, Jena, Germany), real-time PCR, and ompA genotyping. The number and percentage for each infection are shown. Single infections included each species and the designated ompA genotypes (n = 71). C. trachomatis (Ct) trachoma strain C predominated, but single infections with C. psittaci (Cps), C. pecorum (Cp), and C. suis (Cs) also occurred). Mixed infections included those with Ct, Cps, C. pneumoniae (Cpn), Cp, and Cs.

Figure 2

Figure 2

Identification of Chlamydiaceae triple infection by using the ArrayTube (Alere Technologies, Jena, Germany) assay. A) Biotinylated PCR product from a DNA extract was hybridized to a DNA microarray carrying species-specific probes from the 23S rRNA gene locus (17). Bar graph shows specific hybridization signals for genus Chlamydia (1), C. trachomatis (2), C. suis (3), and C. psittaci (4) in sample 67. Other signals represent nonspecific cross-hybridization. B) _omp_A genotyping of the C. trachomatis strain from sample 64 conducted by using the ArrayStrip platform that is specific for C. trachomatis. The best match of this sample was genotype C. The genotype has been determined by automatic comparison of experimentally obtained (black bars) and theoretically constructed (gray bars) hybridization patterns with use of the software's PatternMatch algorithm. The numerical values of matching score MS (measure of similarity between sample and reference strain) and Delta MS (numerical difference between best and second best match) indicate that the identification is highly accurate (21). The rightmost bars represent internal staining control (biotinylated oligonucleotide probe) and spotting buffer (background).

References

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