Abstract: A bacteria filter has a base member with an open circular groove in which an adhesive bonding material anchors one end of a generally cylindrical filter element. The filter element has longitudinally extending pleats and the opposite end of the filter is adhesively secured in an open circular channel in an end cap element opposing the base member. A housing for the filter is sealed to the base member in spaced surrounding relationship with the filter element and has an inlet passage therethrough whereby air may enter the filter device through the inlet passage, flow through the filter element, and be emitted through the outlet passage in the base member. The method of assembling the filter device includes a unique method of retaining the pleated filter element in the desired cylindrical form while bonding the filter element to the base member and/or end cap.