The barriers of the body are the skin, mucous membranes, the lacrimal apparatus, saliva, the epiglottis, sebum, perspiration, gastric juice, urine and vaginal secretions, and transferrin. Each of these plays a role in inhibiting pathogens but remember that this function is not necessarily the primary role for these systems.
The complement system is comprised of a number of molecules that work in sequence to destroy bacterial cells by essentially punching a hole in the bacterial cell. Recall that in the sequence of reactions associated with compliment there are several places where the ancillary effects of the reaction can include inflammation or opsonization.
The initial response to this break in the integrity of the skin will be fostered by the release of chemicals from the damaged tissues. These chemicals act as a chemoattractant for white blood cells such as neutrophils and these cells will follow the chemical scent to the site of the damage and begin phagocytizing any bacteria that have entered through the site. These cells will be followed by monocytes that will differentiate on arrival into macrophages which are powerful phagocytic cells. The entire process will be part of the overall inflammatory response which is part of the innate immune response.