Replication of influenza virus A/Swine/Guangdong/7/06 (H3N2) in guinea pigs. Groups of 18 animals were inoculated intranasally with 100 μL (106 EID50) of virus, or a 100 μL mixture of virus (106 EID50) and S. maltophilia (1.5 × 107 CFU). On days 1, 2, 4, 6 and 8 post-inoculation, three animals from each group were euthanized. Nasal wash, tracheas and lungs were collected for virus titration in eggs. (A) Virus titers in nasal washes. (B) Virus titers in tracheas. Each bar represents the virus titer expressed as mean log10 EID50/mL ± SD. The lower limit of detection was 101.5 EID50/mL, or 101.5 EID50/mL of tissue homogenate. Virus titers at each time point were compared between single virus-inoculated and virus-bacterial co-inoculated groups. * indicates statistically significant difference of means with p < 0.05, ** indicates statistically significant differences of means with p < 0.01.