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Veterinary bacteriology

Species/Subspecies: Paenibacillus larvae
Categories: Causes hemolysis; spore forming; motile
Etymology: Genus name: Almost a Bacillus sp.
Species epithet: from larvae.
Significance:American foulbrood is common in the United States, but also occurs in Sweden, Finland and other European countries. The disease can cause significant economic losses where it is prevalent.
Old Species Name(s):Paenibacillus larvae subsp. larvae och P. larvae subsp. pulvifaciens har nu sammanförts till en art.
Type Strain: ATCC 9545 = CCUG 28515.
Macromorphology (smell): Produces mostly greyish-white colonies with diffuse edges. However, there are strains, which form orange pigmented colonies. Some of these (genotype ERIC 3) gives a clear hemolysis zone on blood agar.
Spore forming and motile rods (0.5-0.8 x 2.5-5.0 µm), which have peritrichous flagella.
Gram +/Gram -:G+, but difficult to gram stain.
Metabolism: Facultatively anaerobic
Other Enzymes: Esculinase +, tryptophanase +, urease -
Biochemical Tests: Citrate -, has mixed acid fermentation (Voges-Proskauer +)
Fermentation of carbohydrates:
Other carbohydrates: Adonitol -, galactose +.
Spec. Char.:
Disease:American foulbrood of honeybees.
Hosts: Honeybee (Apis mellifera)
Clinical Picture: Abnormally high number of dead larvae (even in closed cells). Dead larvae produce a brown viscous residue in the cell, which can be pulled out with a match to a long thread. These residues contain large amounts of bacterial spores and can have a foal smell.
Genome Sequence:
Acc-noStrainSize (bp)Genome
CP003355 04-310 (= DSM 25430) 4 046 337 1c + 1c 
At least three strains have been sequenced and these strains have 0 to 1 circular plasmids.

16S rRNA Seq.:
Acc-noStrainNumber of NTOperon
X60619 ATCC 9545T 1425 

About 75 species and subspecies have been described within the genus Paenibacillus. Many of them were earlier regarded as members of the genus Bacillus.
Legislation: On suspicion of American foulbrood (AFB) in Sweden, a complaint is required to the bee inspector or the provincial government by Swedish law. AFB is included in OIE's A-list of major animal diseases.
Comment:Compare Melisococcus plutonius, which causes European foulbrood.
Reference(s): No. 97, 128, 137
Link: Amerikansk yngelröta - biologi, diagnos och bekämpning


"Dear child has many names" (call it what you will...)

For a long time, Rhodococcus hoagii was refer­red to Rhodo­coccus equi on VetBact, because we experienced some resistance to the name that is now considered to be the correct one, i.e. Rhodococcus hoagii. Now you can find the bacterium in question under the correct name in VetBact, but you can also find the bacterium when searching for the old name. 

Published 2021-10-10. Read more...

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