Fused and mixed clusters were excluded giving a data set of 204 orthologs across 113 organisms.
Only 2 such mixed clusters were found, representing a mere 0.3% of the total number of clusters (Fig. 3).
Interestingly, the only two mixed clusters were both associated with the large subunit ribosomal RNA (rrnL) gene, the only chloroplast encoded gene found in our analyses.
Of the nine studies reporting detailed information on the nationality of clustered foreign-born cases, 0 80% (median 40%) of the "foreign-born only clusters", and 40 100% (median 68.8%) of the mixed clusters, were multinational [ 20– 27, 32].
Mixed clusters were also categorized according to cluster origin, into one of three categories: "Danish" (if comprising predominantly Danish cases), "migrant" (if comprising predominantly migrant cases), or "uncertain" (if comprising an even number of Danes and migrants).
This is an overall estimate and it must be noted that the age of diagnosis for German cases in mixed clusters is lower than for Germans in German-only clusters (8.7 years lower in males and 11.6 years lower in females).
However, TB patients in mixed clusters were no more likely than patients in clusters containing only foreign-born persons to be diagnosed with TB within 1 year, from 1 5 years, or >5 years of arrival (chi square for trend 0.038, p=0.85).
While we observe comparatively low integration indexes in the immigrant cluster, the integration index in the mixed cluster is much higher.
As origin of a mixed cluster is more uncertain than a cluster containing only one nationality of cases, five different criteria were applied to define likely origin of the mixed clusters.
The five criteria used to define origin of a mixed cluster were: 1) ethnicity of first patient in the cluster; 2) ethnicity of first sputum smear positive patient in the cluster; 3) ethnicity of most patients in the cluster; 4) two of three criteria 1-3 meet; and 5) three of three criteria 1-3 met, defines the cluster origin.
