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Volume 7, Number 3—June 2001

Synopsis

Spoligotype Database of Mycobacterium tuberculosis: Biogeographic Distribution of Shared Types and Epidemiologic and Phylogenetic Perspectives

Christophe Sola*Comments to Author , Ingrid Filliol*, Maria Cristina Gutierrez†, Igor Mokrousov*, Véronique Vincent†, and Nalin Rastogi*Comments to Author 
Author affiliations: *Institut Pasteur de Guadeloupe, Pointe à Pitre, Guadeloupe; †Centre National de Référence des Mycobactéries, Institut Pasteur, Paris, France

Main Article

Table 2

Geographic distribution of potentially specific shared types of Mycobacterium tuberculosis reported in a single location (n=122)

Region Country No. of types Types
Americas Guadeloupe 7 12,13,14,15,30,103,259
French Guiana 4 66,76,94,96
Cuba 4 71,74,80,81
USA 46 192,194,197-199,201,202, 205,206,208,210-217,219-235, 237-239,241,243,246,248,256-258
Europe The Netherlands 4 9,18,28,90
United Kingdom 6 16,23,27,38,43,100
France 27 55,57,107-114,116,120,122, 140,141,143-148,170,171, 173,174,184,186
Italy 9 155,157-160,163,165,166,169
Spain 2 104,106
Russia 3 251,252,253
Africa Zimbabwe 6 79,82-85,87
Guinea-Bissau 1 188
Asia Philippines 1 69
Mongolia 2 97, 98

Main Article

1For this purpose, the independent sampling sizes for Europe and the USA were taken as n1 and n2, the number of individuals within a given shared-type "x" was k1 and k2, and in this case, the representativeness of the two samples was p1=k1/n1 and P2=k2/n2, respectively. To assess if the divergence observed between p1 and p2 was due to sampling bias or the existence of two distinct populations, the percentage of individuals (p0) harboring shared-type "x" in the population studied was estimated by the equation p0= k1+k2/n1+n2=n1p1+n2p2/n1+n2. The distribution of the percentage of shared-type "x" in the sample sizes n1 and n2 follows a normal distribution with a mean p0 and a standard deviation of formula imageand formula imagerespectively, and the difference d=p1-p2 follows a normal distribution of mean p0-p0=0 and of variance σd2p12p22 = p0q0/n1+p0q0/n2 or σd2=p0q0 (1/n1+1/n2). The two samples being independent, the two variances were additive; the standard deviation σd= was calculated, and the homogeneity of the samples tested was assessed using the quotient d/σd=p1-p2/formula image. If the absolute value of the quotient d/σd<2, the two samples were considered to belong to a same population (CI 95%) and the variation observed in the distribution of isolates for given shared types could be due to a sampling bias. Inversely, if d/σd>2, then the differences observed in the distribution of isolates for given shared types were statistically significant and not due to potential sample bias.

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