Researchers investigated Chlamydia infections in patients with community-acquired pneumonia and the findings suggest that the role of these infections may be overestimated, with other types of bacteria likely causing the disease. The research study, “Lack of Chlamydia-related bacteria among patients with community-acquired pneumonia,” was published in New Microbes and New Infections.
Community-acquired pneumonia, the most common type, is an important cause of mortality and morbidity worldwide. The most commonly identified pathogens are Streptococcus pneumoniae, Haemophilus influenzae, atypical bacteria (ie, Chlamydia pneumoniae, Mycoplasma pneumoniae, Legionella), and viruses. Still, only about 50 percent of the community-acquired pneumonias are of known etiology.
Chlamydia and Chlamydia-related bacteria have been shown to cause pneumonia and lung infection, and may include some of the agents that cause pneumonia of unknown etiology. However, the routine cultures used to identify the pathogen in these patients often fail to detect this type of bacteria.
In this study, Swiss researchers aimed to reveal the role of the Chlamydia members in lung infection. They used samples collected from 564 patients with community-acquired pneumonia that had been enrolled in a trial comparing two types of therapies, and performed a genetic analysis to detect Chlamydia DNA.
Only one patient, a 79-year old male, had a positive result for Chlamydia, showing the presence of Chlamydia psittaci DNA, a bacteria that is commonly found in bird skin and gut flora. The patient had diabetes and history of coronary artery and cerebrovascular disease, but had not traveled or been in contact with animals.
“[T]he documented C. psittaci infection underlines the importance of a complete diagnostic assessment, including C. psittaci, even in absence of history of exposure to birds.” the authors wrote in their study.
These results contradicted other studies that had detected Chlamydia-related bacteria in patients with community-acquired pneumonias, which the authors believe is due to the different study populations, as they only analyzed non-immunosupressed adults with mild and moderate community-acquired pneumonia, where the other studies included mainly immunocompromised patients.
The findings suggest that outside specific conditions that lead to outbreaks or case clusters of Chlamydia-derived community-acquired pneumonias, the different members of the Chlamydia order are not common agents in this disease.