FIGURE 6.

Chlorogenic acid protects against S. aureus-induced abscess formation in kidney of BALB/c mice. Kidneys of BALB/c mice (N = 8 per group) infected with 2 × 10⁸ CFU S. aureus Newman D2C (WT), ΔSrtA or WT after treatment with CHA (50 mg/kg, three times a day) were removed from mice on the 6 days after intravenous infection. (A–P) Kidneys were inspected for surface abscesses (A,F,K) or fixed in formalin, embedded, thin sectioned and stained with H&E. Histopathology images were acquired with light microscopy at ×100 (B,C,G,H,L,M) and ×400 (D,E,I,J,N,O). Kidneys from mice challenged with WT had a big size of abscesses and enclosed a central population of staphylococci (D, yellow arrowheads), surrounded by a layer of eosinophilic, amorphous material and a large cuff of polymorphonuclear leukocytes (PMNs; D,E, blue rectangular box). There is no abscess founded in kidneys from mice infected with SrtA. Sizes of abscesses were significantly decreased after treated with CHA. Only some slight influx of PMNs (N, blue rectangular box) existed and harbored a few discernable organization of staphylococci (N, yellow arrowheads). (P) Bacterial burden in kidney tissue was measured on the 6 days after intravenous infection. Mean ± SEM of staphylococcal load were calculated as log₁₀ CFU/g in homogenized renal tissues. Statistical significance was calculated with the Student’s t-test; ^∗∗P < 0.01 vs. the WT group.