Bovine Bacillus anthracis isolates from Cameroon were genetically characterized. They showed a strong homogeneity, and they belong, together with strains from Chad, to cluster A␤, which appears to be predominant in western Africa. However, one strain that belongs to a newly defined clade (D) and cluster (D1) is penicillin resistant and shows certain phenotypes typical of Bacillus cereus.Extensive genetic analysis of a large number of strains of Bacillus anthracis, the causative agent of anthrax, led to robust molecular epidemiological data, making this bacterium a model for microbial evolution and the global spread of pathogens and even making it possible for researchers to follow migration or movement of its hosts or host products (5)(6)(7)(8)15). This is possible by virtue of the large data set based on canonical single nucleotide polymorphisms (canSNPs), which classify B. anthracis strains into clades (22), and on multiple-locus variable-number tandem-repeat (VNTR) analysis (MLVA), which groups them further into clusters (6). Although certain geographical regions are extensively sampled, others are poorly studied, which may lead to bias in the analysis of the spread and diversity of strain populations. This, in particular, is the case for western and central African countries, such as Cameroon, where most of Africa's anthrax outbreaks occur (22). A broader genetic diversity of B. anthracis strains is expected in that region due to the higher incidence of anthrax there than elsewhere. In order to improve our knowledge regarding the genetic diversity of B. anthracis, we analyzed bovine strains from seven sites in Cameroon and compared the results with data from a worldwide strain collection. In addition, we characterized in detail a penicillin-resistant strain that caused bovine anthrax in that area. This strain represents a new clade and a new cluster of B. anthracis and shows some genetic traits of Bacillus cereus.Strains of B. anthracis isolated from bovines in various areas of Cameroon (Table 1) were identified using standard methods as described previously (17,23). They all harbored the virulence factor markers pag and cap, which are specific to B. anthracis plasmids pXO1 and pXO2 (19). They were all nonhemolytic and ␥ phage sensitive (Table 1). One strain, JF3964, showed particular phenotypes that are normally found in B. cereus, such as resistance to the B. anthracis-specific ␥ phage and resistance to penicillin. However, in contrast to B. cereus, strain JF3964 was nonhemolytic. These phenotypic criteria are used to discriminate B.anthracis from B. cereus. Additionally, the chromosomal markers sap and Ba813 that were used as specific markers for B. anthracis (17,19) were absent in JF3964. However, JF3964 contained the virulence genes which are associated with the two B. anthracis plasmids pXO1 and pXO2 (19).Genetic strain characterization was performed by canSNP analysis, which best roots the phylogenetic relationship of B. anthracis strains (22), and MLVA, which allows a finer subtyping of the strains (...