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Chlamydia pneumoniae infection in community-acquired pneumonia in Taiwan
1Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, ROC.
Abstract:
Chlamydia pneumoniae is a common cause of pneumonia worldwide. This study examined the role of C. pneumoniae in 229 patients with community-acquired pneumonia. The ages of the patients ranged from 2 to 95 years. Sera were assayed for IgM and IgG antibodies with microimmunofluorescence (MIF). An IgM titer equal to or greater than 1:20 and IgG titer equal to or greater than 1:64 were considered positive. The prevalence of positive IgG among all of the patients was 75.1% (172/229). The seroprevalence was 81.8% (9/11) for patients in the 11- to 20-year-old group, 63.6% (14/22) in the 31- to 40-year-old group and 88.1% (52/59) in the 71- to 80-year-old group. All patients had a negative result for IgM antibody. Twenty-five of the patients had an IgG titer equal to or greater than 1:512, indicating the presence of current infection or reinfection. Age older than 60 years (vs. < or = 60 years) was a risk factor for C. pneumoniae seropositivity in patients with community-acquired pneumonia (p < 0.001). Males had a significantly higher seroprevalence of C. pneumoniae infection (p = 0.1010). Patients older than 60 years were more likely to have C. pneumoniae infection (p = 0.1107). In this series, C. pneumoniae infection accounted for 10.9% (25/229) of community-acquired pneumonia. The most common clinical manifestations included fever (92%), productive cough (52%), white blood cell more than 10,000/mm3 (56%), and bilateral pulmonary infiltrate (60%).
Insights
Chlamydia pneumoniae is a frequent cause of community-acquired pneumonia. This study found high IgG antibody prevalence, especially in older adults, indicating widespread infection, but no IgM antibodies, suggesting past exposure rather than acute illness.
Area of Science:
- Infectious Diseases
- Respiratory Medicine
- Microbiology
Background:
- Chlamydia pneumoniae is a significant global pathogen responsible for pneumonia.
- Community-acquired pneumonia (CAP) presents a substantial public health challenge worldwide.
- Understanding the etiological agents of CAP is crucial for effective treatment and prevention.
Purpose of the Study:
- To investigate the prevalence and role of Chlamydia pneumoniae in adult patients diagnosed with community-acquired pneumonia.
- To identify potential risk factors associated with C. pneumoniae seropositivity in this patient cohort.
- To determine the clinical manifestations associated with C. pneumoniae infections in CAP.
Main Methods:
- A cohort of 229 patients with community-acquired pneumonia (age range 2-95 years) was studied.
- Serum samples were analyzed for IgM and IgG antibodies against C. pneumoniae using microimmunofluorescence (MIF).
- Positive serology was defined by specific IgM (≥1:20) and IgG (≥1:64) titers; high IgG titers (≥1:512) suggested current or recent infection.
Main Results:
- A high overall IgG seroprevalence of 75.1% (172/229) was observed, with no positive IgM results.
- Seroprevalence varied by age group, notably higher in the 11-20 (81.8%) and 71-80 (88.1%) year olds.
- Age over 60 years was identified as a significant risk factor for C. pneumoniae seropositivity (p < 0.001).
- C. pneumoniae accounted for 10.9% (25/229) of the CAP cases, with fever and productive cough being common symptoms.
Conclusions:
- Chlamydia pneumoniae is a common finding in community-acquired pneumonia, particularly indicated by IgG antibodies suggesting past or persistent infection.
- Older age is a significant risk factor for C. pneumoniae seropositivity in CAP patients.
- The absence of IgM antibodies suggests that C. pneumoniae may play a role in recurrent or chronic respiratory conditions rather than solely acute infections in this population.