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Chlamydophila pneumoniae

I. General Information

1. NCBI Taxonomy ID:

2. Disease:

Pneumonia

3. Introduction

Chlamydophila pneumoniae is a species of Chlamydophila bacteria[1][2][3] that infects humans and is a major cause of pneumonia. C. pneumoniae has a complex life cycle and must infect another cell in order to reproduce and thus is classified as an obligate intracellular pathogen. This atypical bacterium commonly causes pharyngitis, bronchitis and atypical pneumonia mainly in elderly and debilitated patients but in healthy adults also. C. pneumoniae infection has been implicated in several chronic lung diseases by serology and direct antigen detection. Acute lower respiratory tract infection caused by C. pneumoniae seems often to precede attacks of asthma in both children and adults but is also involved in some exacerbations of chronic bronchitis. More importantly it seems to be strongly associated with chronic obstructive lung disease irrespective of exacerbation status. Moreover, persistently elevated C. pneumoniae antibody titers have been observed in sarcoidosis and lung cancer (Wiki: Chlamydophila pneumoniae).

4. Microbial Pathogenesis

Chlamydophila pneumoniae is a small bacterium (0.2 to 1 micrometer) that undergoes several transformations during its life cycle. It exists as an elementary body (EB) in between hosts. The EB is not biologically active but is resistant to environmental stresses and can survive outside of a host for a limited time. The EB travels from an infected person to the lungs of a non-infected person in small droplets and is responsible for infection. Once in the lungs, the EB is taken up by cells in a pouch called an endosome by a process called phagocytosis. However, the EB is not destroyed by fusion with lysosomes as is typical for phagocytosed material. Instead, it transforms into a reticulate body and begins to replicate within the endosome. The reticulate bodies must utilize some of the host's cellular machinery to complete its replication. The reticulate bodies then convert back to elementary bodies and are released back into the lung, often after causing the death of the host cell. The EBs are thereafter able to infect new cells, either in the same organism or in a new host. Thus, the life cycle of C. pneumoniae is divided between the elementary body, which is able to infect new hosts but can not replicate, and the reticulate body ,which replicates but is not able to cause new infection (Wiki: Chlamydophila pneumoniae).

5. Host Ranges and Animal Models

In addition to infecting humans, C. pneumoniae also infects and causes disease in Koalas, emerald tree boa (Corallus caninus), iguanas, chameleons, frogs, and turtles (Wiki: Chlamydophila pneumoniae).

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