The performance of antimicrobial susceptibility testing programmes relevant to aquaculture and aquaculture products

Antimicrobial susceptibility testing of bacteria isolated from aquatic animals and their environments may be performed either as part of a monitoring or surveillance programme or to provide guidance for clinical treatments of diseased animals. This technical paper addresses best practice guidelines for the performance of these susceptibility tests. Section 1 discusses the relevance of this document to The FAO Action Plan on Antimicrobial Resistance 2016- 2020. Section 2 provides a general background to the principles of antimicrobial susceptibility testing. It stresses the absolute need for the use of internationally agreed standardized test protocols and the adherence to the quality control requirement of those protocols. It also stresses the importance of the use of consensus-based, internationally harmonized criteria in the interpretation of the meanings that can be given to in-vitro susceptibility data. It provides a discussion of the theory of interpretive criteria and the methods by which they can be calculated. Section 3 discusses the current status of the standard protocols that can be recommended for use in antimicrobial susceptibility testing of bacteria isolated from aquatic animals. Following a consideration of 44 species of bacteria that represent those most frequently isolated from aquatic animals, it demonstrates that the currently available standardized protocols are adequate for the determination of the antimicrobial susceptibility of 37 of them (84 percent). Section 4 discusses the importance of the design of programmes aimed at monitoring or surveillance of antimicrobial resistance associated with the use of antimicrobial agents in the rearing of aquatic animals. These programmes may be performed to address various questions. It is important that the design adopted in any programme generates data appropriate to the question being asked. In this paper four designs are outlined, each of which will provide data for programmes aimed at answering different questions. Section 5 provides some conclusions, while Section 6 gives a list of references. The technical paper is supported by four annexes that provide: (i) a listing of Clinical and Laboratory Standards Institute (CLSI) documents cited in the paper; (ii) a list of the antimicrobial agents most commonly used in aquaculture; (iii) notes on the selection of test protocols for selected Gram-positive cocci; and (iv) guidance on the possible use of epidemiological cut-off values in a clinical context.non-peer-reviewe