Chlamydia pneumoniae: modern insights into an ancient pathogen

Abstract

Chlamydia pneumoniae is an enigmatic human and animal pathogen. Originally discovered in association with acute human respiratory disease, it is now associated with a remarkably wide range of chronic diseases as well as having a cosmopolitan distribution within the animal kingdom. Molecular typing studies suggest that animal strains are ancestral to human strains and that C. pneumoniae crossed from animals to humans as the result of at least one relatively recent zoonotic event. Whole genome analyses appear to support this concept - the human strains are highly conserved whereas the single animal strain that has been fully sequenced has a larger genome with several notable differences. When compared to the other, better known chlamydial species that is implicated in human infection, Chlamydia trachomatis, C. pneumoniae demonstrates pertinent differences in its cell biology, development, and genome structure. Here, we examine the characteristic facets of C. pneumoniae biology, offering insights into the diversity and evolution of this silent and ancient pathogen.

Guanylate Binding Proteins Enable Rapid Activation of Canonical and Noncanonical Inflammasomes in Chlamydia-Infected Macrophages

“…Two Chlamydia species, Chlamydia pneumoniae and Chlamydia trachomatis, are humanadapted pathogens. C. pneumoniae infects alveolar epithelial cells and macrophages, causing acute respiratory as well as chronic diseases (2). C. trachomatis predominantly invades epithelial cells and is responsible for various disease manifestations that depend on the specific bacterial strain and the site of the infection: ocular C. trachomatis strains infect conjunctival epithelial cells, resulting in trichiasis, corneal opacification, and blindness; genital C. trachomatis strains infect cervical epithelial cells and can cause pelvic inflammatory disease and infertility (3).…”

Synergistic Costimulatory Effect of Chlamydia pneumoniae with Carbon Nanoparticles on NLRP3 Inflammasome-Mediated Interleukin-1β Secretion in Macrophages

“…The seroprevalence rates of C. pneumoniae infection, which start to rise relatively early in childhood, are increased by 50% at 20 years of age and subsequently reach 70 to 80% by 60 to 70 years of age (3,4), suggesting most individuals will have had some exposure to the bacterium in their lifetime. Therefore, C. pneumoniae is likely a ubiquitous pathogen in individuals worldwide (4). The symptoms of pulmonary infection vary considerably according to age from asymptomatic or mild illness to serious pneumonia, especially in pediatric infection (1)(2)(3).…”

Planctomycetes DNA in Febrile Aplastic Patients with Leukemia, Rash, Diarrhea, and Micronodular Pneumonia

“…However, as Planctomycetes is part of the gut flora, it would not be surprising if Planctomycetes species were translocated from the gut and caused bacteremia in immunocompromised hosts receiving broad-spectrum antibiotics. Also, tropism for the lung would be congruent with the phylogenetic proximity of Planctomycetes with Chlamydia, a genus also comprising fastidious organisms responsible for pneumonia (1,8). Several elements still need to be confirmed to show that Planctomycetes are pathogenic to humans, including their direct isolation from blood.…”