Free Access
Volume 40, Number 1, January-February 2009
Page(s) 73 - 81
Published online 05 December 2008
Apidologie 40 (2009) 73-81
DOI: 10.1051/apido:2008061

Molecular epidemiology of Paenibacillus larvae infection in Finland

Jaana Pentikäinen1, 2, Eija Kalliainen1, 3 and Sinikka Pelkonen1

1  Veterinary Bacteriology, Research Department, Evira Finnish Food Safety Authority, PO Box 92, 70701 Kuopio, Finland
2  Present address: Eastern Finland Laboratory Centre Joint Authority Enterprise (ISLAB) Department of Clinical Microbiology, Kuopio, Finland
3  Present address: 98800 Savukoski, Finland

Received 4 July 2008 – Revised 15 September 2008 – Accepted 13 October 2008 - Published online 5 December 2008

Abstract - The epidemiology of a Paenibacillus larvae infection, causing American Foulbrood (AFB), was studied regionally in Finland and temporally in the apiaries. Altogether 156 P. larvae isolates from honey or brood samples supplied by 114 beekeepers were analysed by NotI pulsed-field gel electrophoresis (PFGE) and biotyping, as well as for tetracycline resistance. Fifty-two NotI macrorestriction profiles (MRP) and three biotypes were detected. All isolates were susceptible to tetracycline. Most MRPs and biotypes IV and V were widely spread throughout the country, though a few MRPs and biotype I were clustered around certain areas. Analysis of subsequent isolates from 25 beekeepers usually showed persistence of the infection in the apiaries, but in six cases unrelated infections emerged. Typing of contemporary isolates from one beekeeper revealed the presence of the same infection in distant apiaries, thus indicating that the spread of infection was through apicultural practices instead of neighbourhood. NotI PFGE allowed efficient strain discrimination and can be recommended for epidemiological surveillance of AFB.

Key words: Apis mellifera / Paenibacillus larvae / American foulbrood / NotI pulsed-field gel electrophoresis / biotyping

© INRA, DIB-AGIB, EDP Sciences 2008