Table 1.
Description of groups (treated and control) used in the therapeutic assay.
Fig 1.
Bacterial load in kidneys after systemic infection with different MRSA strains.
Groups (four mice per group) of treated (MAb) and untreated (control) mice were infected via IP injection with 2.4x108 CFU of Iberian (black) or 1.6x108 BEC (white) MRSA clones, and bacterial quantitation was performed after 5 days. A. Bacterial load in individual mice: Iberian Control (2.1x105, 4.4x104, 3.1x105, and 2.9x104 CFU); Iberian MAb-treated (8.0x101, 2.0x102, 1.0x101, and 6.0x101 CFU); BEC control (2.0x103, 2.9x104, 2.2x105, and 5.2x104 CFU); BEC MAb-treated (2.0x101, 1.0x101, 1.0x101, and 3.0x101 CFU) (*p<0.05 for Iberian and BEC assays). B. Comparative mean for both groups challenged with Iberian and BEC MRSA, respectively (Iberian control: 2.11x105 CFU; Iberian MAb treated: 8.75x101 CFU; BEC control: 7.57x104 CFU; BEC MAb treated: 1.75x101 CFU).
Fig 2.
Bacterial load in kidneys of mice treated with MAb (IgG) and F(ab’)2 fragment.
Mice (n = 7 mice/group) treated with MAb or F(ab’)2 anti-PBP2a fragment and controls (mAb 4G2 and not treated) were infected via IP administration of 2x108 CFU of the BEC MRSA clone. Bacterial quantitation was performed 5 days later. Significant difference between treated and control groups was seen (*p<0.05). There was no significant difference between the control groups (untreated and mAb 4G2-treated).
Fig 3.
Effect of prophylactic treatment with anti-PBP2a MAb in a challenge with a lethal dose of BEC and Iberian MRSA clones.
Previous treatment increased survival rates in the treated groups. Mice were challenged by IP inoculation with 4.2x108 or 3.3x108 CFU of the Iberian and BEC MRSA clones, respectively (*p<0.05).
Fig 4.
Effect of anti-PBP2a MAb and vancomycin monotherapy and MAb + vancomycin combination therapy.
The bacterial load in kidneys are represented by group (five mice/group). Mice were infected with an IP inoculum of 7.0x106 CFU of the BEC MRSA clone and then euthanized after 3 days. (*p<0.05 between the control group versus the other groups). The mean of recovered CFU by groups: Control group: 5020 CFU; Vancomycin-treated group: 336 CFU; MAb-treated group: 186 CFU; group treated with the MAb + vancomycin combination therapy: 52 CFU. The number of CFU/mice are represented in Supporting Information (S1 Table).
Fig 5.
Biodistribution of the MAb in vivo.
Serum, lungs, spleen, and kidneys of 9-week-old female BALB/c mice were obtained at different time points (12, 24, 48, 72, and 96 h) after IP injection of purified murine MAb (500 μg). Serum and tissues were processed and submitted for an ELISA to estimate the MAb concentration (μg/mL of serum or homogenated tissue) as described in the Material and methods. Control animal concentrations were estimated to be 0 (absorbance values were very close to those found at 0 μg of each respective standard curve, ranging from– 0.0044 to 0.0055). Results are shown as the mean ± S.E.M. of two measurements of three different animals for each timepoint.