Form used to assess the relative quality of studies identified by the systematic review search strategy. For each section (Arabic numerals), three options are given((i)-(iii)). The one that best describes the study being analysed is chosen and allocated as a score. At the bottom of the form, these scores are added (maximum possible score = 12) and the relative reliability of the study scored accordingly as high, medium or low. The form also allowed the noting of any other relevant information about the study described, such as the source of the micro-organism looked at.