Chlamydia pneumoniae infection in adults with chronic cough compared with healthy blood donors

Abstract

In a small uncontrolled study, persistent cough has recently been found to be associated with serological evidence of acute Chlamydia pneumoniae infection. In order to assess whether C. pneumoniae plays a role in chronic cough, the prevalence of C. pneumoniae infection in 201 adult patients with chronic cough was compared with the prevalence in 106 healthy blood donors without respiratory tract symptoms in the preceding 3 months. A microimmunofluorescence antibody test was used to determine C. pneumoniae antibodies in the immunoglobulin (Ig)M, IgG and IgA fractions. Further, nasopharyngeal aspirates from the 201 patients were examined for C. pneumoniae deoxyribonucleic acid by polymerase chain reaction (PCR).As judged by serology, nine patients (4%) and one control (1%) had acute C. pneumoniae infection, and 92 patients (46%) and 42 controls (40%) had previous or chronic C. pneumoniae infection. Of the nine patients with acute infection, three were C. pneumoniae PCR positive, and they all had an IgM antibody titre response. The remaining six patients had either an IgG antibody titre of $512 (five patients) or an IgA antibody titre of $512 (one patient). None of these six patients had detectable IgM antibodies.The mean cough period for the five IgG positive patients (10.8 weeks) was significantly longer than the mean cough period for the remaining patient population (6.4 weeks; p=0.004).It is concluded that Chlamydia pneumoniae infection was not statistically significantly more prevalent in patients with chronic cough than in healthy blood donors, and that Chlamydia pneumoniae appears to have a minor role in patients with chronic cough. Direct detection of Chlamydia pneumoniae by polymerase chain reaction on nasopharyngeal aspirates is highly correlated with detectable immunoglobulin M antibodies, but in the late stages of prolonged cough serological testing of immunoglobulin G and immunoglobulin A may be more beneficial for obtaining a microbiological diagnosis. Eur Respir J 2000; 16: 108±111.

Prevalence of antibody to Chlamydia pneumoniae in residents of Japan, the Solomon Islands, and Nepal.

“…Because the half-life of IgA is generally short, 16 it is used as an index of current or recent infection. 22,23 Chlamydia pneumoniae is also an important epidemic pathogen, causing recurrent infection. 24 Because the Solomon Islands are a region that is highly endemic for malaria, 25 respiratory diseases, and viral infections, 26 recurrent C. pneumonae infections might also occur there frequently.…”

Measurement ofChlamydia pneumoniae-Specific Immunoglobulin A (IgA) Antibodies by the Microimmunofluorescence (MIF) Method: Comparison of Seven Fluorescein-Labeled Anti-Human IgA Conjugates in an In-House MIF Test Using One Commercial MIF and One Enzyme Immunoassay Kit

“…The independent association between elevated C. pneumoniae IgA antibody levels and fibrinogen levels further indicates that chronic infections could be of importance for disease activity (25). However, several studies have failed to show any association between C. pneumoniae-specific IgA antibodies and chronic lung or cardiovascular diseases (2,3,23,26,28). The present results clearly indicate that there are large variations in the abilities of different commercial anti-IgA FITC conjugates to detect IgA antibodies in serum.…”

Two Quality Control Exercises Involving Nucleic Acid Amplification Methods for Detection of Mycoplasma pneumoniae and Chlamydophila pneumoniae and Carried Out 2 Years Apart (in 2002 and 2004)

“…From previous investigations, we have learned that the sensitivity of molecular diagnostics using respiratory samples may be compromised by the presence of inhibitory factors in the samples (2,5,8,14,28,29). Therefore, three different BAL pools were used in the 2004 QC panels.…”

“…Although all tests aim to be rapid, sensitive, specific, and easy to perform, results of NAATs may be unreliable because of cross-contamination, inappropriate treatment of the clinical samples leading to loss of target nucleic acid, or the presence of inhibitors (2,5,12,14,26,27).…”

“…For the 2002 QC exercise, specimens were spiked with M. pneumoniae at concentrations of 5,000, 500, 50, and 0 color-changing units (CCU)/100 l. The limit of detectability was 50 CCU/100 l. A multitude of nucleic acid amplification tests (NAATs) have been described for the detection of Mycoplasma pneumoniae and Chlamydophila pneumoniae in respiratory specimens (6,17). In addition to in-house PCR tests, commercial kits are becoming available, such as the LCx for C. pneumoniae (Abbott Laboratories) (8) and the NucliSens Basic kit (bioMérieux), for which the primers and the target-specific biotinylated capture probe are to be synthesized for each target by the user (15).Although all tests aim to be rapid, sensitive, specific, and easy to perform, results of NAATs may be unreliable because of cross-contamination, inappropriate treatment of the clinical samples leading to loss of target nucleic acid, or the presence of inhibitors (2,5,12,14,26,27).To date, only one study compared the results of different NAATs for the detection of C. pneumoniae in respiratory specimens in different centers (8), and four studies compared the results of amplification methods performed in different centers for the detection of C. pneumoniae in atheroma specimens (2,3,11,21). To our knowledge, no such studies have been published for M. pneumoniae.…”