Prevalence and association of sIgA in saliva and Pseudomonas aeruginosa infection in TB patients: a cross-sectional study

Abstract Objectives Pseudomonas aeruginosa is pathogenic in immunocompromised individuals. It has several complex mechanisms for evading human immunity. The objective of the study was to examine the secretory immunoglobulin A (sIgA) mediated immune response in saliva to detect P. aeruginosa in pulmonary tuberculosis. Methods The infection with P. aeruginosa was categorized according to the Leeds criteria in the final 86 individuals who were proven to have pulmonary tuberculosis by polymerase chain reaction. Levels of serum immunoglobulin G (IgG) and sIgA which are specific to P. aeruginosa were measured using the method of ELISA. Results Patients in the “free of infection (patients who were infected with P. aeruginosa in the lower respiratory tract at the beginning of the study later became negative)” and “intermittent colonized (patients who were infected with P. aeruginosa throughout the study)” groups had substantially higher median baseline sIgA levels in saliva and a much greater proportion of sIgA positive than patients who were never colonized (patients who were found to be P. aeruginosa negative throughout the study) (p=0.038). Median baseline IgG level was 10.7 (1.7–145.0), 8.3 (2.5–22.9), and 6.7 (3.3–17.1) for the patients categorized as “intermittent colonization”, “free of infection” and “never colonized”, respectively. After 3 years of study, sIgA level was found in significant high level among the patients with infection of P. aeruginosa (p=0.003). Conclusions Secretory IgA may be readily collected from saliva and is a useful diagnostic technique for determining whether P. aeruginosa infection has occurred.