Comparison of genovars and Chlamydia trachomatis infection loads in ocular samples from children in two distinct cohorts in Sudan and Morocco

PLoS Negl Trop Dis. 2021 Aug 9;15(8):e0009655. doi: 10.1371/journal.pntd.0009655. eCollection 2021 Aug.

Abstract

Trachoma is a blinding disease caused by repeated conjunctival infection with different Chlamydia trachomatis (Ct) genovars. Ct B genovars have been associated with more severe trachoma symptoms. Here, we investigated associations between Ct genovars and bacterial loads in ocular samples from two distinct geographical locations in Africa, which are currently unclear. We tested ocular swabs from 77 Moroccan children (28 with trachomatous inflammation-follicular (TF) and 49 healthy controls), and 96 Sudanese children (54 with TF and 42 healthy controls) with a Ct-specific real-time polymerase chain reaction (PCR) assay. To estimate bacterial loads, Ct-positive samples were further processed by multiplex real-time qPCR to amplify the chromosomal outer membrane complex B and plasmid open reading frame 2 of Ct. Genotyping was performed by PCR-based amplification of the outer membrane protein A gene (~1120 base pairs) of Ct and Sanger sequencing. Ct-positivities among the Moroccan and Sudanese patient groups were 60·7% and 31·5%, respectively. Significantly more Sudanese patients than Moroccan patients were genovar A-positive. In contrast, B genovars were significantly more prevalent in Moroccan patients than in Sudanese patients. Significantly higher Ct loads were found in samples positive for B genovars (598596) than A genovar (51005). Geographical differences contributed to the distributions of different ocular Ct genovars. B genovars may induce a higher bacterial load than A genovars in trachoma patients. Our findings emphasize the importance of conducting broader studies to elucidate if the noted difference in multiplication abilities are genovar and/or endemicity level dependent.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Bacterial Outer Membrane Proteins / genetics*
  • Case-Control Studies
  • Child
  • Child, Preschool
  • Chlamydia trachomatis / genetics*
  • Conjunctivitis, Inclusion / drug therapy
  • Conjunctivitis, Inclusion / microbiology*
  • Conjunctivitis, Inclusion / transmission
  • Female
  • Genotype
  • Humans
  • Infant
  • Male
  • Morocco
  • Polymerase Chain Reaction
  • Sudan
  • Trachoma / genetics*

Substances

  • Bacterial Outer Membrane Proteins
  • OMPA outer membrane proteins

Grants and funding

TB was partly funded by the “Laura Bassi Centers of Expertise” program of the Austrian Federal Ministry of Economy through the Austrian Research Promotion Agency (FFG Project Number: 822768) www.ffg.at. The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.