Cold agglutinins in HIV-seropositive participants and diagnosis of respiratory disease due to Mycoplasma pneumoniae.

Objectives. Cold agglutinin (CA) titers are one among the first pathological indicators for diagnosing Mycoplasma pneumoniae disease. We prospectively studied the prevalence of CAs in 300 HIV-positive and 75 HIV-negative individuals with respiratory disease in Chennai, India. Methods. The cold agglutination test was used and retrospectively compared with the results of a particle agglutination test. Results. While CAs were positive in 51 HIV cases, particle agglutination test detected anti-M pneumoniae antibodies from 43 cases with HIV disease (P = .001). The seroprevalence of CAs was 2.6% (n = 2) among HIV-negative participants. The mean CD4 count in CApositive and -negative HIV cases was 107.4 + 121.2 and 259.2 + 247.2 cells/µL (P = .001), respectively. Conclusion. Our report suggests a basis for the existence of CAs in HIV-positive cases. Definitive diagnosis may be done only when CA detection is used in conjunction with a specific test.