First cultivation and characterization of Mycobacterium ulcerans from the environment.
BACKGROUND
Mycobacterium ulcerans disease, or Buruli ulcer (BU), is an indolent, necrotizing infection of skin, subcutaneous tissue and, occasionally, bones. It is the third most common human mycobacteriosis worldwide, after tuberculosis and leprosy. There is evidence that M. ulcerans is an environmental pathogen transmitted to humans from aquatic niches; however, well-characterized pure cultures of M. ulcerans from the environment have never been reported. Here we present details of the isolation and characterization of an M. ulcerans strain (00-1441) obtained from an aquatic Hemiptera (common name Water Strider, Gerris sp.) from Benin.


RESULTS
One culture from a homogenate of a Gerris sp. in BACTEC became positive for IS2404, an insertion sequence with more than 200 copies in M. ulcerans. A pure culture of M. ulcerans 00-1441 was obtained on Löwenstein-Jensen medium after inoculation of BACTEC culture in mouse footpads followed by two other mouse footpad passages. The phenotypic characteristics of 00-1441 were identical to those of African M. ulcerans, including production of mycolactone A/B. The nucleotide sequence of the 5' end of 16S rRNA gene of 00-1441 was 100% identical to M. ulcerans and M. marinum, and the sequence of the 3' end was identical to that of the African type except for a single nucleotide substitution at position 1317. This mutation in M. ulcerans was recently discovered in BU patients living in the same geographic area. Various genotyping methods confirmed that strain 00-1441 has a profile identical to that of the predominant African type. Strain 00-1441 produced severe progressive infection and disease in mouse footpads with involvement of bone.


CONCLUSIONS
Strain 00-1441 represents the first genetically and phenotypically identified strain of M. ulcerans isolated in pure culture from the environment. This isolation supports the concept that the agent of BU is a human pathogen with an environmental niche.
Portaels
Françoise
F
Institute of Tropical Medicine, Antwerpen, Belgium. portaels@itg.be
Meyers
Wayne M
WM
Ablordey
Anthony
A
Castro
António G
AG
Chemlal
Karim
K
de Rijk
Pim
P
Elsen
Pierre
P
Fissette
Krista
K
Fraga
Alexandra G
AG
Lee
Richard
R
Mahrous
Engy
E
Small
Pamela L C
PL
Stragier
Pieter
P
Torrado
Egídio
E
Van Aerde
Anita
A
Silva
Manuel T
MT
Pedrosa
Jorge
J
D000818:Animals; D001427:Bacterial Toxins / Q000378:metabolism; D002478:Cells, Cultured; D004783:Environmental Microbiology; D005260:Female; D005528:Foot / Q000382:microbiology; D005838:Genotype; D006430:Hemiptera / Q000382:microbiology; D018942:Macrolides; D008264:Macrophages / Q000382:microbiology; D013058:Mass Spectrometry; D051379:Mice; D008807:Mice, Inbred BALB C; D019911:Mycobacterium ulcerans / Q000145:classification / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism / Q000502:physiology*; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012336:RNA, Ribosomal, 16S / Q000235:genetics
D001427:Bacterial Toxins; D018942:Macrolides; D012336:RNA, Ribosomal, 16S; C117218:mycolactone