In a mouse model of secondary bacterial pneumonia (SBP), at 3 h postbacterial infection (PBI), EF3030 burden and lung damage were equivalent, but halothane (HAL)-induced alterations in cytokine expression were observed in flu-infected mice. CD-1 mice were inoculated intranasally with 40 plaque-forming units A/PR/8/34 influenza virus (SBP) or mock infected (mock). Mock-HAL and SBP-HAL mice (white bars) were exposed to 2% HAL for 2 h just before infection (day 0) and again for 2 h on day 4 postviral infection (PVI). Mock-cont and SBP-cont mice (black bars) received ketamine sedation. On day 6 PVI, mice were inoculated with 2.5 × 10⁶ CFU EF3030, and 3 h later (3 h PBI), mice were killed, BAL was performed, and lungs were harvested. (A) Nonclarified recovered BAL fluid and lung homogenates were titered for EF3030 to determine the total EF3030 lung burden. Cell-free BAL fluid was assessed for (B) albumin, (C) interleukin (IL)-1β, (D) IL-6, (E) tumor necrosis factor (TNF)-α, (F) MCP-1, (G) MIP-2, (H) KC, and (I) interferon (IFN)-γ. Sample sizes are displayed above groups. *P < 0.05, **P < 0.01 SBP-HAL compared with SBP-cont. Data are expressed as mean ± SEM. BAL = bronchoalveolar lavage; CFU = colony-forming units; cont = control; EF3030 = Streptococcus pneumoniae.