These results indicate that beta-defensins and LL37 have versatile antibacterial activity against oral bacteria.

SummaryEnteropathogenic Escherichia coli (EPEC) and enterohaemorrhagic E. coli (EHEC) are closely related pathogens. Both use a type III secretion system (TTSS) encoded by the 'locus of enterocyte effacement' (LEE) to subvert and attach to epithelial cells through the injection of a repertoire of effector molecules. Here, we report the identification of a new TTSS translocated effector molecule called Cif, which blocks cell cycle G 2 /M transition and induces the formation of stress fibres through the recruitment of focal adhesions. Cif is not encoded by the LEE but by a lambdoid prophage present in EPEC and EHEC. A cif mutant causes localized effacement of microvilli and intimately attaches to the host cell surface, but is defective in the ability to block mitosis. When expressed in TTSS competent LEE-positive pathogens, Cif is injected into the infected epithelial cells. These cells arrested at the G 2 / M phase displayed accumulation of inactive phosphorylated Cdk1. In conclusion, Cif is a new member of a growing family of bacterial cyclomodulins that subvert the host eukaryotic cell cycle.

We identified a novel pathogenicity island inInterestingly, these strains are mainly isolated from other sources of infections and not from patients with bullous impetigo or staphylococcal scalded-skin syndrome. This strongly suggests that ETD might play a pathogenic role in a broader spectrum of bacterial infections than previously considered.

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The complete nucleotide sequence of pETB, a 38.2-kb Staphylococcus aureus plasmid encoding the exfoliative toxin B (ETB), was determined. A total of 50 open reading frames were identified on the plasmid genome and, among these, 32 showed sequence similarity to known proteins. pETB contains three copies of IS257, which divide the pETB genome into three regions: (i) a cadmium resistance operon-containing region, (ii) a lantibiotic production gene-containing region, and (iii) the remaining part where genes for plasmid replication and/or maintenance are dispersed. In the third region, genes of various kinds of functions are present among the replication-and maintenance-related genes. They include two virulence-related genes, the etb gene and a gene encoding a novel ADP-ribosyltransferase closely related to EDIN, which belongs to the C3 family of ADPribosyltransferases modifying Rho GTPases. They also include genes for a cell wall-anchoring surface protein and a phage resistance protein. Based on the determined sequence of pETB, the genome structures of etb-bearing plasmids (ETB plasmids) from various clinical isolates were analyzed by the PCR scanning method. The data indicate that, although the ETB plasmids are highly heterogeneous in genome size, the fundamental genome organization is well conserved. The size variation of the plasmid is mainly attributed to defined regions which may be hot spots for gene shuffling.Exfoliative toxin (ET) is an exotoxin produced by staphylococcal species, causing blisters in human and animal skin (29). ET-producing Staphylococcus aureus is involved in staphylococcal scalded-skin syndrome (SSSS), or Ritter disease, and bullous impetigo in neonates (18,29,32). Serologically, ETs causing diseases in human have been divided into two major serotypes: ETA and ETB (5, 28). Both types cause intraepidermal cleavage in the granular layer, without epidermal necrolysis or inflammatory response of skin (5,16,28). The mechanism whereby ETs produce exfoliation of the skin has been unknown for a long time, but several lines of evidence have suggested that they are acting as a protease: (i) amino acid sequences of ETA and ETB show similarity with the S. aureus V8 serine protease (14), and the catalytic site of V8 protease is conserved in ETA (6); (ii) partially purified ETs preincubated with serine protease inhibitors exhibits delayed skin exfoliation (14); (iii) substitution of the serine residue with glycine in the putative catalytic site of ETA completely abolishes the exfoliative activity of the toxin (37, 38); and (iv) crystal structures of ETA (12, 56) and ETB (55) have recently been determined, and both types were shown to structurally belong to the chymotrypsin family of serine proteases. More recently, it has been shown that ETA digests desmoglein I, which is one of the major desmosome proteins present in the epidermal layer of human skin (4).The genes for ETs are detected only in some S. aureus clinical strains. This limited distribution of the ET genes suggested that certain S. aureus str...