Analytica Chimica Acta 586 (2007) 304–311 Degradation of incurred tylosin to desmycosin—Implications for residue analysis of honey Thomas S. Thompson a,∗ , Stephen F. Pernal b , Donald K. Noot a , Adony P. Melathopoulos b , Johan P. van den Heever a a Alberta Agriculture, Food & Rural Development (AAFRD), Food Safety Division, Agri-Food Laboratories Branch, 6909, 116th Street, Edmonton, Alberta, Canada T6H 4P2 b Agriculture & Agri-Food Canada (AAFC), P.O. Box 29, Beaverlodge, Alberta, Canada T0H 0C0 Received 19 June 2006; received in revised form 13 September 2006; accepted 20 September 2006 Available online 29 September 2006 Abstract As a result of the application of tylosin to honey bee colonies for the control of American foulbrood disease, antibiotic residues may exist in honey destined for human consumption. It has been recognized that the parent compound, tylosin A, degrades in acidic media such as honey to yield the antimicrobially active degradation product, desmycosin. Data is presented documenting levels of incurred tylosin and desmycosin in honey resulting from simulated therapeutic applications of a commercial formulation of tylosin during the fall. It is demonstrated that honey destined for human consumption should be analyzed for both tylosin A and desmycosin (tylosin B) rather than the parent antibiotic alone. An analytical method that permits the simultaneous determination of tylosin A and desmycosin in honey using liquid chromatography–tandem mass spectrometry is also presented. Crown Copyright © 2006 Published by Elsevier B.V. All rights reserved. Keywords: Tylosin; Desmycosin; Antibiotics; Honey; Residues; Liquid chromatography–tandem mass spectrometry (LC–MS/MS); American foulbrood (AFB); Paenibacillus larvae 1. Introduction Similar to humans and animals, honey bees (Apis mellifera L.) are afflicted with a variety of diseases caused by bacteria, fungi, protozoa and viruses [1]. American foulbrood (AFB), caused by the spore-forming bacterium Paenibacillus larvae [2], is considered to be the most serious disease plaguing apiculture today and is nearly cosmopolitan in its distribution [3]. To ini- tiate infection, larval bees must consume the bacterial spores within 48 h of hatching, and normally die during the late larval or pre-pupal stages [4]. AFB is highly contagious and can be readily disseminated by bees robbing honey from neighbour- ing hives, the feeding of spore-contaminated pollen and honey, or the reuse of contaminated beekeeping equipment. Though honey bees possess inherent mechanisms of resistance against P. larvae [5–8], high levels of spores produce clinical infections that inevitably lead to the demise of colonies. The long-lived ∗ Corresponding author. Tel.: +1 780 415 4530; fax: +1 780 415 4527. E-mail address: tom.thompson@gov.ab.ca (T.S. Thompson). nature of the spores [9,10], their virulence [11], as well as their resistance to heat, desiccation, and chemical disinfectants [12], have resulted in the establishment of AFB as a global threat to apiculture. Unlike humans and animals, a very small number of antibi- otics have been used to treat bacterial diseases in honey bees. In some parts of the world, AFB is controlled through cultural prac- tices such as the isolation and destruction of infected colonies and burning of contaminated equipment. In areas such as the western hemisphere, American foulbrood has been controlled primarily through the use of antibiotics. Sulfathiazole was used as early as the 1940s, however the persistence of residues in har- vested honey resulted in its discontinuation for use in beekeeping [13]. Oxytetracycline was also discovered to be an effective treatment for AFB [14] and has been used continuously since the 1950s. Unlike sulfathiazole, it has a relatively short half-life in honey and therefore problems with antibiotic residues are less likely to occur [15–17]. Currently, oxytetracycline is the only antibiotic registered in Canada for the treatment of honey bee bacterial brood dis- eases [18]. It has been used prophylactically in many countries 0003-2670/$ – see front matter. Crown Copyright © 2006 Published by Elsevier B.V. All rights reserved. doi:10.1016/j.aca.2006.09.043