An apparatus and method are provided for visually monitoring, detecting, and/or determining the presence, absence, and/or growth of harmful or potentially harmful bacterial microorganisms beneath a wound dressing, in one example used to cover an indwelling central venous catheter or other catheter. A bacteria detection apparatus includes a barrier membrane, a permeable membrane for placement proximate a wound or a catheter insertion site, and an indicator between the barrier membrane and the permeable membrane for indicating the presence of bacteria proximate the permeable membrane. A method of using a bacterial growth detection apparatus is also provided.