2.1 Data collection
A systematic literature review was performed using a rigorous search strategy in the online version of the Science Citation Index Expanded (SCI-EXPANDED) from the Web of Science (WoS) database (http://www.isiknowledge.com), which is one of the largest and comprehensive bibliographic databases covering multidisciplinary areas. WoS was chosen as it is the oldest citation database, including records that go back to 1900 (Aghaei Chadegani et al., 2013). Search results were delimited based on the following Boolean query executed within a single search (conducted in November 2019). No time and geographical location restrictions were placed on these searches, and only those published in English were retrieved. The searches were last updated on 26th November 2019. The search strategy consisted of compiling three search strings, one for each category (antimicrobial resistance and wildlife) and combining these by the Boolean operator “AND” to obtain only the intersection. Specifically, we used the following Boolean search statement: #1 “antimicrobial resistance”: “ANTIMICROBIAL” OR “ANTIBIOTIC” AND “RESISTANT” OR “RESISTANCE” and #2 “wildlife”: “WILDLIFE” “MAMMAL” “BIRD” “REPTILE” “FERAL” “FREE RANGE” and the interception consisted in #1 AND #2. The search was made to the whole data series available, that is, in the last 40 years, from 1979 to 2019. Articles originating from England, Scotland, Northern Ireland, and Wales were reclassified as being from the United Kingdom (UK).