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Parachlamydiaceae: potential emerging pathogens
1Unité des Rickettsies, Université de la Méditerranée, Marseille, France.
Abstract:
Parachlamydiaceae, which naturally infect amoebae, form a sister taxon to the Chlamydiaceae on the basis of the Chlamydia-like cycle of replication and 80% to 90% homology of ribosomal RNA genes. Because intra-amoebal growth could increase the virulence of some intracellular bacteria, Parachlamydiaceae may be pathogenic. Arguments supporting a pathogenic role are that Chlamydia pneumoniae, a well-recognized agent of pneumonia, was shown to infect free-living amoebae and that another member of the Chlamydiales, Simkania negevensis, which has 88% homology with Parachlamydia acanthamoebae, has caused pneumonia in adults and acute bronchiolitis in infants. The recent identification of a 16S rRNA gene sequence of a Parachlamydiaceae from bronchoalveolar lavage is additional evidence supporting potential for pathogenicity.
Insights
Parachlamydiaceae, bacteria that infect amoebae, may be pathogenic. Evidence suggests these bacteria, similar to Chlamydia pneumoniae, could cause respiratory illnesses like pneumonia in humans.
Area of Science:
- Microbiology
- Pathogen Discovery
- Molecular Biology
Background:
- Parachlamydiaceae are amoeba-infecting bacteria.
- They share characteristics with Chlamydiaceae, including replication cycles and ribosomal RNA gene homology.
- Intra-amoebal growth can enhance bacterial virulence.
Purpose of the Study:
- To evaluate the potential pathogenicity of Parachlamydiaceae.
- To explore the link between amoeba-infecting bacteria and human respiratory diseases.
Main Methods:
- Comparative analysis of ribosomal RNA gene homology.
- Review of existing evidence on Chlamydiales pathogenicity.
- Identification of bacterial 16S rRNA gene sequences in clinical samples.
Main Results:
- Parachlamydiaceae exhibit 80-90% ribosomal RNA gene homology with Chlamydiaceae.
- Chlamydia pneumoniae infects amoebae and causes pneumonia.
- Simkania negevensis, related to Parachlamydiaceae, causes human respiratory infections.
- A Parachlamydiaceae 16S rRNA gene sequence was found in bronchoalveolar lavage.
Conclusions:
- Parachlamydiaceae possess characteristics suggesting pathogenic potential.
- The presence of Parachlamydiaceae DNA in respiratory samples indicates a possible role in human lung infections.