Staphylococcus caprae strains carry determinants known to be involved in pathogenicity: a gene encoding an autolysin-binding fibronectin and the ica operon involved in biofilm formation

The atlC gene (1,485 bp), encoding an autolysin which binds fibronectin, an d the ica operon, involved in biofilm formation, were isolated from the chr omosome of an infectious isolate of Staphylococcus caprae and sequenced. At lC (155 kDa) is similar to the staphylococcal autolysins Atl, AtlE, Aas (48 to 72% amino acid identity) and contains a putative signal peptide of 29 a mino acids and two enzymatic centers (N-acetylmuramoyl-L-alanine amidase an d endo-beta -N-acetylglucosaminidase) interconnected by three imperfect fib ronectin-binding repeats. The glycine-tryptophan (GW) motif found in the ce ntral and end part of each repeat may serve for cell surface anchoring of A tlC as they do in Listeria monocytogenes. The S, caprae ica operon contains four genes closely related to S, epidermidis and S, aureus icaA, icaB, ica C, and icaD genes (greater than or equal to 68% similarity) and is preceded by a gene similar to icaR (greater than or equal to 70% similarity). The p olypeptides deduced from the S, caprae ica genes exhibit 67 to 88% amino ac id identity to those of S, epidermidis and S, aureus ica genes. The ica ope ron and icaR gene were analyzed in 14 S, caprae strains from human specimen s or goats' milk Some of the strains produced biofilm, and others did not. All strains carry the ica operon and icaR of the same sizes and in the same relative positions, suggesting that the absence of biofilm formation is no t related to the insertion of a mobile element such as an insertion sequenc e or a transposon.