Interleukin-1 and interleukin-6 in community acquired pneumonia: Bacteremic pneumococcal pneumonia vs Mycoplasma pneumoniae pneumonia

Purpose: To determine and compare interleukin-1 (IL-1) and interleukin-6 (IL-6) levels in 2 groups of patients with community-acquired pneumonia (CAP) caused by S. pneumoniae (SP) or M. pneumoniae (MP) in the acute and convalescent phases. We assumed that the difference in the clinical manifestations of the disease would be expressed in the cytokine levels. Methods: Twenty patients with bacteremic SP CAP and 20 patients with MP CAP (diagnosed serologically) comprised the SP and MP groups, respectively. All 40 patients survived hospitalization and underwent a follow-up examination one month after discharge. Results: In the acute phase of CAP, IL-6 levels were significantly higher in the SP group than in the MP group (p=0.014). In the same phase IL-1 levels were higher in the MP group compared to the SP group (p=0.046). In the convalescent phase cytokines were identified in a considerable number of patients in both groups, in part at levels above those of normal controls. The level of IL-1 was significantly higher in this phase in the MP group than in the SP group (p=0.03), but there was no significant difference between the groups in IL-6 levels. Conclusions: The levels of IL-1 and IL-6 were different between patients with SP CAP and MP CAP during the acute phase. In the convalescent phase cytokine levels remained high in CAP patients, but a difference between the patient groups was seen only for IL-1. Further studies are required on this issue. Clinical implications: An association may exist between the clinical pictures of CAP caused by different etiological agents and the IL-1 and IL-6 levels.