Evaluation of kinetic behaviour of two preparations of tylosin administered in beehives for American foulbrood control

Abstract

We compared the kinetic behaviour of tylosin administered to beehives by dusting or paper-pack placement through three treatment protocols (D, PP, CONTROL). D (dusting): tylosin, divided in four portions, was sprinkled over the ends of the hives' top bars weekly for four weeks (n=3); PP (paper-pack placement): tylosin in paper packs was administered at two-week intervals (n=3); CONTROL (control): the hives were left untreated (n=3). In every inspection, from each of the nine hives, fifty young (2-day-old) larvae were sampled for drug analysis. The concentration of tylosin in the young larvae was determined by a microbiological assay with Geobacillus stearothermophilus ATCC 12980 as test organism. The (mean±SD) maximum concentration (C max ) for D was 136.0±194.0 and for PP -144.0±187.4 µg/mL; the time to reach C max (t max ) was 1.5±0.9 h for D and 1.8 ± 1.8 h for PP. The area under the tylosin behaviour kinetics curve between 0-1392 h with D was 308.7±185.2 and with PP: 326.4±141.0 µg/h/mL, indicating no statistical difference between the treatments (P>0.05). The shorter duration of paper-pack-administered tylosin observed in the larvae implied a lower risk of antibiotic residues in the resulting honey.

Antimicrobial Resistance Genes in Bacteria Isolated From Japanese Honey, and Their Potential for Conferring Macrolide and Lincosamide Resistance in the American Foulbrood Pathogen Paenibacillus larvae

“…In another previous study, honey bee colonies containing around 30,000 worker bees were fed 500 g of synthetic honey with 200 mg or 400 mg of TS for 48 h, and the maximum concentration of TS in 48-h-old larvae was less than 1 μg/g even when treated with 400 mg of TS ( Bernal et al, 2011 ). Similar to the study by Reynaldi et al (2017) , TS is used by dusting methods in Japan, and only 150 mg of TS is used for 10,000 adult bees. The dose of TS in Japan is lower than and almost equivalent to those in the studies by Reynaldi et al (2017) and Bernal et al (2011) , respectively; therefore, the TS concentration in young larvae is expected to be less than 1–4 μg/ml.…”

“…Similar to the study by Reynaldi et al (2017) , TS is used by dusting methods in Japan, and only 150 mg of TS is used for 10,000 adult bees. The dose of TS in Japan is lower than and almost equivalent to those in the studies by Reynaldi et al (2017) and Bernal et al (2011) , respectively; therefore, the TS concentration in young larvae is expected to be less than 1–4 μg/ml. In contrast, MICs of TS for DTK384ermC and DTK384pJ18TS1mac were 8–16 μg/ml, suggesting that ermC -positive P. larvae is clinically resistant to TS.…”

“…However, proliferation of ermC -positive P. larvae in larvae will hardly be arrested even by TS. In the previous study by Reynaldi et al (2017) , beehives with 25,000 adult bees were treated with TS by dusting methods; i.e., the mixture consisting of 114 g of confectioner’s sugar, 5 g of cherry jelly and 1 g of TS was divided into four, 250 mg of TS to 30-g portions, and each portion was sprinkled over the ends of the hives’ top bars for four weeks at one-week intervals. According to the article, the mean concentration of TS in 2-day-old larvae measured by microbiological assay with Geobacillus stearothermophilus ATCC 12980 was always less than 4 μg/ml ( Reynaldi et al, 2017 ).…”

“…In the previous study by Reynaldi et al (2017) , beehives with 25,000 adult bees were treated with TS by dusting methods; i.e., the mixture consisting of 114 g of confectioner’s sugar, 5 g of cherry jelly and 1 g of TS was divided into four, 250 mg of TS to 30-g portions, and each portion was sprinkled over the ends of the hives’ top bars for four weeks at one-week intervals. According to the article, the mean concentration of TS in 2-day-old larvae measured by microbiological assay with Geobacillus stearothermophilus ATCC 12980 was always less than 4 μg/ml ( Reynaldi et al, 2017 ). In another previous study, honey bee colonies containing around 30,000 worker bees were fed 500 g of synthetic honey with 200 mg or 400 mg of TS for 48 h, and the maximum concentration of TS in 48-h-old larvae was less than 1 μg/g even when treated with 400 mg of TS ( Bernal et al, 2011 ).…”