Chlamydia pneumoniae
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Chlamydia pneumoniae
Chlamydophila pneumoniae is a species of Chlamydophila bacteria that infects humans and is a major cause of pneumonia.
Until recently it was known as Chlamydia pneumoniae, and that name is used as an alternate in some sources. In some cases, to avoid confusion, both names are given.
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. In addition to its role in pneumonia, there is evidence associating C. pneumoniae with atherosclerosis, Alzheimer's disease and with asthma.[citation needed] The full genome sequence for C. pneumoniae was published in 1999.
C. pneumoniae also infects and causes disease in Koalas, emerald tree boa (Corallus caninus), iguanas, chameleons, frogs, and turtles.
The first known case of infection with C. pneumoniae was a case of sinusitis in Taiwan.
This atypical bacterium commonly causes pharyngitis, bronchitis and atypical pneumonia[6] mainly in elderly and debilitated patients but in healthy adults also.
| Kingdom | Bacteria |
|---|---|
| Phylum | Chlamydiae |
| Order | Chlamydiales |
| Family | Chlamydiaceae |
| Genus | Chlamydophila |
| Species | C. pneumoniae |
| Binomial | Chlamydophila pneumoniae |
Contents |
Surface Characteristics
The surface consists of specific LPS structures. It has the core lipid A moiety and 3-deoxy-D-manno-oct-2-ulosonic acid (Kdo) core but lacks the distal O-polysaccharide region.
Pathogenic Activity
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.
Virulence
Symptoms of infection with C. pneumoniae are indistinguishable from other causes of pneumonia. These include cough, fever, and difficulties breathing. A slightly red hard palate, and a whitening of the back of the tongue are very common. Patients infected with C. pneumoniae often have nasal congestion, chest pressures and depression. C. pneumoniae more often causes pharyngitis, laryngitis, and sinusitis than other causes of pneumonia; however, because many other causes of pneumonia result in these symptoms, differentiation is not possible. Likewise, a physical examination by a health provider does not typically provide information which allows for a definite diagnosis.
Diagnosis of C. pneumoniae may be confounded by prior infections with this microorganism. Examination of sputum or the secretions of the respiratory tract may reveal signs of the bacteria. Otherwise, examination of the blood may reveal antibodies against the bacteria. Interpretation may require a period of six weeks in order to reanalyze the antibodies and to determine whether the infection was new or old. Examination of the blood may also show proteins (antigens) from C. pneumoniae, either through direct fluorescent antibody testing, enzyme-linked immunosorbent assay (ELISA), or polymerase chain reaction (PCR).
Chest x-rays of lungs infected with C. pneumoniae
