- Interleukin-1beta (IL-1beta) and interleukin-6 (IL-6) levels in 20 patients with bacteremic Streptococcus pneumoniae community-acquired pneumonia (CAP) were compared with these cytokine levels in 20 patients with Mycoplasma pneumoniae CAP. All 40 patients survived hospitalization and underwent a follow-up examination one month later. Serum IL-1beta and IL-6 levels were determined by the enzyme immunoassay (EIA) method using commercial kits. In the acute phase of CAP, IL-6 levels were significantly higher in the S. pneumoniae group (p = 0.014), while IL-1beta levels were higher in the M. pneumoniae group (p = 0.046). In the convalescence phase, the two cytokines were detected in a considerable number of patients in both groups. In this phase, only the level of IL-1beta was significantly higher in the M. pneumoniae group than in the S. pneumoniae group (p = 0.03). We conclude that the levels of IL-1beta and IL-6 are different between patients with S. pneumoniae-CAP and M. pneumoniae-CAP during the acute phase. In the convalescence phase, cytokine levels remain high in some of the CAP patients, but a significant difference between the groups exists only for IL-1beta. Further studies are required.