Staphylococcus haemolyticus is a member of the coagulase-negative staphylococci (CoNS). It is part of the skin flora of humans, and its largest populations are usually found at the axillae, perineum, and inguinal areas. S. haemolyticus also colonizes primates and domestic animals. Infections can be localized or systemic, and are often associated with the insertion of medical devices. The highly antibiotic-resistant phenotype and ability to form biofilms make S. haemolyticus a difficult pathogen to treat.
Biology and biochemistry
S. haemolyticus is nonmotile, nonsporulating, facultatively anaerobic, and Gram-positive. Cells are typically coccus-shaped and range from 0.8 to 1.3 μm in diameter. It lives on a wide variety of substrates, including glucose, glycerol, maltose, sucrose, and trehalose. It also tests positive for acetoin production, arginine, dihydrolase, benzidine, catalase, hemolysis, and lipase; it tests negative for coagulase, DNase, ornithine decarboxylase and phosphatase
As noted, some S. haemolyticus ORFs differ from S. aureus and S. epidermidis. Some of these ORFs encode gene products with known biological features, such as the regulation of RNA synthesis, the transport of ribose and ribitol, and the essential components of nucleic acid and cell wall teichoic acid biosynthesis. Other unique ORFs likely encode products involved with bacterial pathogenesis and at least three of these ORFs show homology to staphylococcal hemolysins.
{| class="wikitable"
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! Class !! Antimicrobial Agent !! MIC (mg/L) !! ORF ID !! Gene Name !! Product !! Location
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| Penicillins || Oxacillin || >512 ||SH0091 || mecA || Penicillin-binding protein 2' || ΨSCCmec(h1435)
|-
| || Ampicillin || 64 || SH1764 || blaZ || β-Lactamase || Tn552
|-
| || methicillin || || || mecA || Penicillin-binding protein 2' || ΨSCCmec(h1435)
|-
| Cephalosporins || Ceftizoxime || >512 || SH0091 || mecA || Penicillin-binding protein 2' || ΨSCCmec(h1435)
|-
| Macrolides || Erythromycin || >512 || pSHaeB1 || ermC || rRNA adenine N-6-methyltransferase || Plasmid pSHaeB
|-
| || || || SH2305 || msrSA || ATP-dependent efflux system || πSh1
|-
| || || || SH2306 || mphBM || Macrolide 2'-phosphotransferase || πSh1
|-
| quinolones || Ofloxacin || 8 || SH0006 || gyrA || DNA gyrase (topoisomerase II) subunit A (point mutation C7313T) ||
|-
| || || || SH1553 || parC (grlA) || Topoisomerase IV subunit A (point mutation G1598138A) ||
|-
| Tetracyclines || Tetracycline || 2 || || || ||
|-
| || Minocycline || 0.5 || || || ||
|-
| Aminoglycosides || Kanamycin || >512 || SH1611 || aacA-aphD || Bifunctional aminoglycoside N-acetyltransferase and aminoglycoside phosphotransferase || Tn4001
|-
| || Tobramycin || 16 || SH1611 || aacA-aphD || Bifunctional || Tn4001
|-
| || Gentamicin || 64 || SH1611 || aacA-aphD || Bifunctional || Tn4001
|-
| Glycopeptides || Vancomycin || 4 || || || ||
|-
| || Teicoplanin || 64 || || || ||
|-
| Fosfomycin || Fosfomycin || >512 || pSHaeA1 || fosB || Glutathione transferase || Plasmid pSHaeA
|}
Cell wall
Like other Gram-positive microbes, S. haemolyticus has a thick, rather homogenous, cell wall (60-80 nm) composed of peptidoglycan, teichoic acid, and protein. Peptidoglycan of group A3 (with L-lysine as the diamino acid in position 3 of the peptide subunit and a glycine-rich interpeptide bridge) is a characteristic feature of this microbe, and the two predominant cross-bridges are COOH-Gly-Gly-Ser-Gly-Gly-NH<sub>2</sub> and COOH-Ala-Gly-Ser-Gly-Gly-NH<sub>2</sub>. Alterations of these cross-bridges are implicated in glycopeptide resistance. S. haemolyticus strain JCSC1435 contains a capsule operon located within the “oriC environ”. Biofilm formation increases antibiotic resistance S. haemolyticus biofilms are not polysaccharide intercellular adhesin (PIA) dependent, and the lack of the ica operon (the gene cluster that encodes the production of PIA) can be used to distinguish S. haemolyticus isolates from other CoNS species. In a study of 64 S. haemolyticus strains, production of SEA, SEB, SEC, and/or SEE was noted (only SED was absent). In addition, 31.3% of the strains were found to produce at least one type of enterotoxin. The most closely related species of S. haemolyticus is Staphylococcus borealis. Human infections include: native valve endocarditis, sepsis, peritonitis, and urinary tract, wound, bone, and joint infections. Like other CoNS, S. haemolyticus is often associated with the insertion of foreign bodies, such as prosthetic valves, cerebrospinal fluid shunts, orthopedic prostheses, and intravascular, urinary, and dialysis catheters. and able to form biofilms, which makes infections especially difficult to treat. and multidrug resistance is common.