Novel non-mecA-containing staphylococcal chromosomal cassette composite island containing pbp4 and tagF genes in a commensal staphylococcal species: a possible reservoir for antibiotic resistance islands in Staphylococcus aureus.
Among methicillin-resistant Staphylococcus aureus isolates, a staphylococcal chromosomal cassette containing the mecA gene (SCCmec) is integrated into the chromosome at a unique site. SCCmec also contains unique ccrAB recombinase genes mediating its integration and excision from the genome and is flanked by characteristic left and right direct- and inverted-repeat sequences. A few non-mecA-containing SCC elements that have the other molecular features described above have recently been described. The origin of these cassettes is not clear. We have identified two new members of the SCC family integrated within orfX in Staphylococcus epidermidis strain ATCC 12228, neither of which carries mecA. One is a 57-kb element flanked by a unique 28-bp SCC direct repeat. It was called the SCC composite island (SCC-CI) because it carries a 19-kb SCC element (SCCpbp4) nested within it. SCCpbp4 contains pbp4 and tagF genes, as well as one pair of ccrAB genes (allotype 2) flanked by classical SCC-specific terminal repeats. External to SCCpbp4, SCC-CI contains a second pair of ccrAB genes (allotype 4), three IS431 elements, and genes mediating resistance to heavy metals. Genes mediating restriction-modification that may facilitate horizontal transfer are also present within SCC-CI, both within and outside SCCpbp4. Several novel arrangements of the SCC direct and inverted repeats were identified. Several long stretches of homology with other SCCs were found within and outside SCCpbp4. In view of the fact that SCC-CI was found in a commensal species, it may represent a reservoir for sequences involved in genetic shuffling between staphylococci and may contribute to the diversity found in SCC elements.
Mongkolrattanothai
Kanokporn
K
Section of Pediatric Infectious Diseases, Department of Pediatrics, University of Chicago, Chicago, Illinois 60637, USA.
Boyle
Susan
S
Murphy
Trudy V
TV
Daum
Robert S
RS
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics*; D002648:Child; D002876:Chromosomes, Bacterial / Q000235:genetics*; D004269:DNA, Bacterial / Q000235:genetics; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D006602:Hexosyltransferases / Q000235:genetics*; D006801:Humans; D016106:Methicillin Resistance / Q000235:genetics; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000235:genetics; D002267:Muramoylpentapeptide Carboxypeptidase / Q000235:genetics*; D046915:Penicillin-Binding Proteins; D010458:Peptidyl Transferases / Q000235:genetics*; D012150:Polymorphism, Restriction Fragment Length; D011257:Pregnancy Proteins / Q000235:genetics*; D011995:Recombination, Genetic; D012091:Repetitive Sequences, Nucleic Acid; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013203:Staphylococcal Infections / Q000382:microbiology; D013210:Staphylococcus / Q000187:drug effects / Q000235:genetics*; D013211:Staphylococcus aureus / Q000187:drug effects / Q000235:genetics; D013212:Staphylococcus epidermidis / Q000187:drug effects / Q000235:genetics; D017855:Transferases (Other Substituted Phosphate Groups) / Q000235:genetics*
D001426:Bacterial Proteins; D002352:Carrier Proteins; D004269:DNA, Bacterial; D046915:Penicillin-Binding Proteins; D011257:Pregnancy Proteins; C034156:pregnancy-associated growth factor; D010458:Peptidyl Transferases; D006602:Hexosyltransferases; D017855:Transferases (Other Substituted Phosphate Groups); C072175:CDP glycerol glycerophosphotransferase; D002267:Muramoylpentapeptide Carboxypeptidase