Objective: To study the antibacterial activity of aqueous extract of Urena lobata (DTH) on Staphylococcus aureus in vivo. Method: One hundred and eight KM mice were randomly divided into 9 groups:the normal group

the model group

the high-

medium-

low-dose DTH groups (40

20

10 g·kg-1)

the cefazolin group (0.5 g·kg-1)

the DTH plus cefazolin group (DTH 20 g·kg-1

cefazolin 0.5 g·kg-1)

the levofloxacin group (0.09 g·kg-1)

the DTH plus levofloxacin group (DTH 20 g·kg-1

levofloxacin 0.09 g·kg-1) of 12 each. The mouse pneumonia model of S. aureus infection was established by nasal cavity instillation. The different medicines were administrated to the mice after inoculation for 4 days. The lung tissue homogenate colony culture numbers of the mouse were monitored. The white blood cell count (WBC)

the percent of neutrophile granulocyte (NEU%)

absolute neutrophil count (NEU)

immune globulin G (IgG) and IgM were detected. The antibacterial effects on bacterial pneumonia mice were tested. Result: The lung tissue homogenate colony culture number was (7.212±0.578)

(6.210±0.570)×108 CFU·g-1

respectively

in the medium-and high-dose DTH groups

was (3.928±0.165)

(2.042±0.076)×108 CFU·g-1

respectively

in the cefazolin group and DTH plus cefazolin group

which were lower than those in the model group (P <0.01). Meanwhile

the results were better in the DTH plus cefazolin group. The lung tissue homogenate colony culture number was (5.375±0.837)

(4.888±0.820)×108 CFU·g-1

respectively

in the levofloxacin group and the DTH plus levofloxacin group

which were lower than those in the model group (P <0.01). Meanwhile

the results were better in the DTH plus levofloxacin group. The inflammatory exudate in the bronchial lumen and alveolar inflammatory cells infiltration decreased

alveolar structure was restored in the high-

medium-dose DTH groups and the DTH plus cefazolin

DTH plus levofloxacin groups. Moreover

the counts of WBC

NEU%

NEU and IgG

IgM decreased in the high-dose DTH group and the DTH plus cefazolin

DTH plus levofloxacin groups. Conclusion: The results suggest that DTH has a certain degree of antibacterial effects on S. aureus in vivo. There are different degrees of combination effects against S. aureus when combined with cefazolin sodium or levofloxacin.