Clinical Deterioration in Community Acquired Infections Associated with Lymphocyte Upsurge in Immunocompetent Hosts

Abstract

Clinical deterioration during the course of community-acquired infections can occur as a result of an exaggerated immune response of the host towards the inciting pathogens, leading to immune-mediated tissue damage. Whether a surge in the peripheral lymphocyte count can be used as a surrogate marker indicating the onset of immunopathological tissue damage is not known. In this study, we report the clinical presentations and outcomes of a cohort of immunocompetent patients with non-tuberculous community acquired infections who experienced clinical deterioration during hospital stay (n=85). 12 (14.1%) patients had a surge in lymphocyte count preceding their clinical deteriorations, and their diagnoses included viral pneumonitis <citeref rid="b4">(4)</citeref>, viral encephalitis <citeref rid="b3">(3)</citeref>, scrub typhus <citeref rid="b2">(2)</citeref>, leptospirosis <citeref rid="b1">(1)</citeref>, brucellosis <citeref rid="b1">(1)</citeref>, and dengue haemorrhagic fever <citeref rid="b1">(1)</citeref>. The clinical manifestations during deterioration ranged from interstitial pneumonitis <citeref rid="b6">(6)</citeref>, airway obstruction <citeref rid="b1">(1)</citeref>, CNS disturbances <citeref rid="b4">(4)</citeref>, and systemic capillary leak syndrome <citeref rid="b1">(1)</citeref>, all of which were thought to represent immunopathological tissue damages. When compared with patients without lymphocyte surge, these patients were more likely to be infected with fastidious/viral pathogens (0 vs 12; p<0.05), in addition to having lower mean baseline lymphocyte counts (403±181 vs 1143±686 cells/μl; p<0.05). We postulate that the peripheral lymphocyte count may be a useful surrogate marker indicating the presence of immunopathological damage during clinical deterioration in certain infectious diseases.