Community-Associated Staphylococcus aureus from Sub-Saharan Africa and Germany: A Cross-Sectional Geographic Correlation Study

Abstract

Clonal clusters and gene repertoires of Staphylococcus aureus are essential to understand disease and are well characterized in industrialized countries but poorly analysed in developing regions. The objective of this study was to compare the molecular-epidemiologic profiles of S. aureus isolates from Sub-Saharan Africa and Germany. S. aureus isolates from 600 staphylococcal carriers and 600 patients with community-associated staphylococcal disease were characterized by DNA hybridization, clonal complex (CC) attribution, and principal component (PCA)-based gene repertoire analysis. 73% of all CCs identified representing 77% of the isolates contained in these CCs were predominant in either African or German region. Significant differences between African versus German isolates were found for alleles encoding the accessory gene regulator type, enterotoxins, the Panton-Valentine leukocidin, immune evasion gene cluster, and adhesins. PCA in conjunction with silhouette analysis distinguished nine separable PCA clusters, with five clusters primarily comprising of African and two clusters of German isolates. Significant differences between S. aureus lineages in Africa and Germany may be a clue to explain the apparent difference in disease between tropical/(so-called) developing and temperate/industrialized regions. In low-resource countries further clinical-epidemiologic research is warranted not only for neglected tropical diseases but also for major bacterial infections.

Figure 1

Distribution of the 22 most prevalent clonal complexes (CC) in Africa and Germany among isolates from colonization and infection. CCs of low prevalence (<6 isolates) where grouped together (others). The CCs were sorted in ascending order according to the total number of isolates in the respective CC. The proportions of clinical (red) and nasal (green) isolates in the African and German group are shown. Differences in the distribution of CCs between Africa and Germany were calculated with Fisher’s exact test; *p < 0.05, **p < 0.001.

Figure 2

Characteristic genotypic patterns of isolate subgroups detected by DNA microarray. The cluster analysis of 1200 S. aureus isolates was performed using the principal component analysis (PCA). Each dot represents one isolate. Dots are colour coded according to the study sites in Africa (Ifakara, Tanzania (IT), Lambarene, Gabon (LG), Manhiça, Mozambique (MM)) and Germany (Münster (MW), Freiburg (FR), Homburg (HS)). Major clusters that correspond to multilocus sequence typing clonal complexes (CC) are highlighted. Genes that were significantly (p < 0.01) associated with the respective CC are mentioned. Virulence factors that were significantly associated with ≥4 CCs are not displayed. Isolates encircled with a dashed line belong to CC1, CC5, CC6, CC7, CC9, CC12, CC20, CC25, CC49, CC50, CC59, CC80, CC88, CC97, CC101, CC188, CC395, CC509, CC707, CC913, CC1021, CC1290 or ST580, ST1093, ST2370, ST2733, ST2734, ST2735, ST2744, and ST2678.