Staphylococcus haemolyticus
A Microbial Biorealm page on the genus Staphylococcus haemolyticus
Classification
Higher order taxa
Bacteria; Firmicutes; Bacilli; Bacillales; Staphylococcaceae; Staphylococcus
Species
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NCBI: Taxonomy |
Staphylococcus haemolyticus
Description and significance
Staphylococus haemolyticus is a coagulase-negative member of the genus Staphylococcus. The bacteria can be found on normal human skin flora and can be isolated from axillae, perineum, and ingunial areas of humans. S.haemolyticus is also the second most common coagulase-negative staphylocci presenting in human blood.
Coagulase-negative staphylococci are usually considered low-virulent pathogens comparing to the well-known pathogenic coagulase-positive Staphylococcus aureus. However, recent studies suggest that coagulase-negative staphylococci have emerged as a major cause of infection. Staphylococcus haemolyticus itself is also a remarkable opportunistic baterial pathogen that is well-known for its highly antibiotic-resistant phenotype. The bacteria can cause meningitis, skin or soft tissue infections, prosthetic join infections, or bacteremia. The ability of the bacteria to simultaneously resist against multiple types of antibiotic has been observed and studied for a long time. Common antibiotics that are subject to resistance in S haemolyticus include methicillin, gentamycin, erythormycin, and uniquely among staphylococci, glycopeptide antibiotics. The resistance genes for each type of anitbiotic can be located on the chromosome (methicillin), on the plasmids (erythromycin) or on both chromosome and plasmids (gentamycin).
In order to study the multi-drug resistant ability of Staphylococcus haemolyticus and its pathogenic characters, researchers have sequenced the whole genome of one strain, JCSC1435. Beside the bacteria’s antibiotic resistance genes, the study of the sequence also revealed a surprising number of homologous insertion sequences which might be responsible for the frequent genomic arrangement observed in this organism.
Genome structure
The genome of Staphylococcus haemolyticus (strain JCSC1435) includes a circular chromosome of 2,685,015 bp and 3 plasmids of 2,300 bp, 2,366 bp and 8,180 bp.
Comparative genomic analysis has revealed significant similarities and differences between the genomes of S.haemolyticus and those of the other two well-known staphylococci, S.aureus and S.epidermis. Beside the comparable genome sizes, a large proportion of open reading frames (orfs) are conserved both in the sequences and in their order on the chromosome.However, the study also found a region on the chromosome that is unique for each of the 3 organisms. This region locates near the chromosome origin of replication (oriC), and therefore is called “oriC environ”.
Only 2% of the orfs found in S.haemolyticus are pathogenic factors. The corresponding number in the more virulent S.aureus is 6%. Many genes coding for important virulent determinants of S.aureus such as protein A and coagulase locate in the oriC environ and are not found in S.haemolyticus. On the other hand, the oriC environ of S.haemolyticus contains the operon coding for the biosynthesis of its polysaccharide capsule. It has been suggested that the capsule operon of S.haemolyticus might have been introduced exogenously into the species and give them a survival advantage within human host
Cell structure and metabolism
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Ecology
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Pathology
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Application to Biotechnology
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Current Research
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References
Edited by Bao D. Truong, student of Rachel Larsen
