Staphylococcus haemolyticus

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Staphylococcus haemolyticus
Staphylococcus haemolyticus.png
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Bacteria
Phylum: Bacillota
Class: Bacilli
Order: Bacillales
Family: Staphylococcaceae
Genus: Staphylococcus
Species:
S. haemolyticus
Binomial name
Staphylococcus haemolyticus
Schleifer & Kloos, 1975 [1]

Staphylococcus haemolyticus is a member of the coagulase-negative staphylococci (CoNS). [2] It is part of the skin flora of humans, [3] and its largest populations are usually found at the axillae, perineum, and inguinal areas. [4] S. haemolyticus also colonizes primates and domestic animals. [4] It is a well-known opportunistic pathogen, and is the second-most frequently isolated CoNS ( S. epidermidis is the first). [5] Infections can be localized or systemic, and are often associated with the insertion of medical devices. [6] [7] [8] The highly antibiotic-resistant phenotype and ability to form biofilms make S. haemolyticus a difficult pathogen to treat. [5] Its most closely related species is Staphylococcus borealis . [9]

Contents

Biology and biochemistry

S. haemolyticus is nonmotile, nonsporulating, facultatively anaerobic, and Gram-positive. Cells are typically coccus-shaped and range from 0.8-1.3 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 [2]

Growth conditions

Optimal growth occurs between 30 and 40 °C in the presence of oxygen and 10% NaCl. However, some strains can grow at temperatures that range between 18 and 45 °C. Growth at 15 °C or 15% NaCl is poor or absent. [2]

Genome structure

The S. haemolyticus strain JCSC1435 genome contains a 2,685,015 bp chromosome and three plasmids of 2,300 bp, 2,366 bp, and 8,180 bp. The chromosome is comparable in size to those of S. aureus and S. epidermidis and contains a similar G+C content. In addition, a large proportion of the open reading frames (ORFs) are conserved across all three species. On average, orthologous ORFs are 78% identical. However, S. haemolyticus does have unique chromosome regions distributed near oriC (the origin of chromosomal DNA replication), and these regions are collectively referred to as the “oriC environ”. [10]

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. [10]

The S. haemolyticus genome also contains many insertion sequences (ISs). These IS elements may promote frequent genomic rearrangements which accelerate the diversification of the species. Theoretically, these adaptations might help S. haemolyticus overcome the adverse effects of chemical exposure (i.e. the use of antibiotics). The table below contains a list of genes known to be associated with S. haemolyticus antibiotic resistance. [10] [11]

ClassAntimicrobial Agent MIC (mg/L) ORF ID Gene NameProductLocation
Penicillins Oxacillin >512SH0091mecA Penicillin-binding protein 2' ΨSCCmec(h1435)
Ampicillin 64SH1764blaZ β-Lactamase Tn552
methicillin mecA Penicillin-binding protein 2' ΨSCCmec(h1435)
Cephalosporins Ceftizoxime >512SH0091mecA Penicillin-binding protein 2' ΨSCCmec(h1435)
Macrolides Erythromycin >512pSHaeB1ermCrRNA adenine N-6-methyltransferase Plasmid pSHaeB
SH2305msrSAATP-dependent efflux systemπSh1
SH2306mphBMMacrolide 2'-phosphotransferaseπSh1
Quinolones Ofloxacin 8SH0006gyrA DNA gyrase (topoisomerase II) subunit A (point mutation C7313T)
SH1553parC (grlA) Topoisomerase IV subunit A (point mutation G1598138A)
Tetracyclines Tetracycline 2
Minocycline 0.5
Aminoglycosides Kanamycin >512SH1611aacA-aphDBifunctional aminoglycoside N-acetyltransferase and aminoglycoside phosphotransferaseTn4001
Tobramycin 16SH1611aacA-aphDBifunctionalTn4001
Gentamicin 64SH1611aacA-aphDBifunctionalTn4001
Glycopeptides Vancomycin 4
Teicoplanin 64
Fosfomycin Fosfomycin >512pSHaeA1fosB 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-NH2 and COOH-Ala-Gly-Ser-Gly-Gly-NH2. [2] [12] Alterations of these cross-bridges are implicated in glycopeptide resistance. [12] S. haemolyticus teichoic acids are water-soluble polymers with repeating phosphodiester groups covalently linked to peptidoglycan. Peptidoglycan type L-Lys-Gly 3.5-4.0, L-Ser0.9-1.5 Teichoic acid contains both glycerol and N-acetylglucosamine. The major cell wall fatty acids are CBr-15, CBr-17, C18, and C20. [2]

Capsule

Certain strains of S. haemolyticus are capable of producing a capsular polysaccharide (CP). [10] [13] S. haemolyticus strain JCSC1435 contains a capsule operon located within the “oriC environ”. [10] This operon contains 13 ORFs in a 14,652-bp region and is referred to as the capsh locus. The first seven genes of capsh (capAsh through capGsh) are homologous to the S. aureuscap5 or cap8 locus. However, capH through capM are unique to S. haemolyticus, [10] and this region encodes enzymes for a unique trideoxy sugar residue that is N-acylated by aspartic acid. [13]

CP production is influenced by culture medium and growth phase. Cultivation in tryptic soy broth (TSB)], TSB with 1% glucose, brain heart infusion broth, or Columbia broth with 2% NaCl favors the production of CP; cultivation on Columbia salt agar plates is suboptimal. Only trace amounts of CP are generated before the end of exponential phase, and the maximal rate of CP production does not occur until early stationary phase. [13]

CP is considered a virulence factor because it provides resistance against complement-mediated polymorphonuclear neutrophil phagocytosis.[ citation needed ]

Biofilm formation

The ability to adhere to medical devices and subsequently form biofilms is a major virulence factor associated with S. haemolyticus. [3] [5] [14] [15] Biofilm formation increases antibiotic resistance [5] [14] [15] and often leads to persistent infections. [16] [17] 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. [3] [13] [15]

Biofilm formation is influenced by a variety of factors including carbohydrates, proteins, and extracellular DNA. Detachment assays with NaIO4, proteinase K, or DNase result in 38%, 98%, and 100% detachment, respectively. The high level of detachment associated with DNase treatment has led several authors to suggest a cell-to-surface and/or cell-to-cell adhesion function for extracellular DNA. Biofilm formation also appears to be influenced by the presence of glucose and NaCl. Biofilm formation is enhanced when cultivated in TSB with 1% glucose and decreased when cultivated in TSB with 3% NaCl. [15] The production of a capsular polysaccharide decreases biofilm formation. [13]

Subinhibitory concentrations (subminimum inhibitory concentrations) of the antibiotic dicloxacillin also affect the growth of S. haemolyticus biofilms. Biofilms formed in the presence of subinhibitory concentrations of dicloxacillin contain less biomass and have an altered composition. They are thinner, cover less surface area, and are less hydrophobic, but they also have an increased level of resistance to dicloxacillin. [14]

Toxins

Some S. haemolyticus strains produce enterotoxins (SE) and/or hemolysins. [10] [18] 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. [18]

Identification

S. haemolyticus can be identified on the species level using a variety of manual and automated methods. The most frequently employed are: the reference method (based on growth tests), API ID 32 Staph (bioMe´rieux), Staph-Zym (Rosco), UZA (a rapid 4-h method), and polymerase chain reaction and electrophoretic analysis of the 16S rRNA, hsp60, or sodA gene sequence. Preference towards a particular method usually depends on convenience, economics, and required specificity (some species have identical 16S rRNA). [7] [19] The most closely related species of S. haemolyticus is Staphylococcus borealis . [9]

MethodTests performedInterpretation
Reference16 conventional growth tests including: colony pigment, DNase, alkaline phosphatase, ornithine decarboxylase, urease, acetoin production, novobiocin sensitive, polymyxin resistance, and acid production from D-trehalose, D-mannitol, D-mannose, D-turanose, D-xylose, D-cellobiose, maltose, and sucroseResults are compared to the literature on staphylococcal species [19]
API ID 32 Staph (bioMe´rieux)A bacterial suspension is added to a set of wells containing dried substrates for 26 colorimetric tests.After 24 hours of incubation at 37 °C, and the addition of a few other reagents, the results are determined by an automated computer using APILAB ID 32 software [19]
Staph-Zym (Rosco)A bacterial suspension is added to minitubes for 10 metabolic or enzymatic testsThe results are determined by color changes, after 24 hours of incubation, and tests for polymyxin and novobiocin susceptibility [19]
UZA (a rapid 4-hour method)This method is a two-step process. Step one consists of three tests measured after four hours incubation at 37 °C: acid production from D-trehalose, urease, and alkaline phosphatase. Step two includes four possible tests, which are administered as needed after 24 hours of incubation at 37 °C. They are: ornithine decarboxylase, novobiocin susceptibility, fosfomycin susceptibility, and anaerobic growthResults are compared to the literature on staphylococcal species [19]
PCR and electrophoresisUses gene specific degenerate primers to amplify pieces of DNA, these fragments are resolved using electrophoresis, and then purified for DNA sequencingResults are determined by a sequence analysis [7]

Clinical importance

S. haemolyticus is the second-most clinically isolated CoNS (S. epidermidis is the first) and it is considered an important nosocomial pathogen. [20] Human infections include: native valve endocarditis, sepsis, peritonitis, and urinary tract, wound, bone, and joint infections. [3] [4] [5] [13] Infrequent soft-tissue infections usually occur in immunocompromised patients. [21] 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. [6] [7] [8] S. haemolyticus is multi-drug resistant [22] and able to form biofilms, which makes infections especially difficult to treat. [17]

Vascular catheter-associated infections

Staphylococcus on a catheter Staphylococcus on catheter.png
Staphylococcus on a catheter

S. haemolyticus can colonize central venous catheters and cause serious medical complications. Colonization occurs when S. haemolyticus migrates from the skin, along the external surface of the device, or from the hub, due to manipulation by health care workers. In either scenario, a high probability exists that the microbe will form a biofilm. These infections can remain localized or become systemic (i.e. bacteremia). The severity of infection varies depending on the type of catheter, frequency of manipulation, and virulence factors of the S. haemolyticus strain. Removal of the catheter is usually considered to be the best treatment, but this is not always possible. Alternatively, vancomycin or teicoplanin may be administered. [8] Recent evidence suggests that glycopeptides can be supplemented with β-lactams to work synergistically. [20]

Antibiotic resistance

S. haemolyticus has the highest level of antibiotic resistance among the CoNS. [15] Various strains are resistant to one or more of these antibiotics: penicillins, cephalosporins, macrolides, quinolones, tetracyclines, aminoglycosides, glycopeptides, and fosfomycin (see table in Genome structure), [5] [10] [22] [23] and multidrug resistance is common. [22] As indicated above, even glycopeptide-resistant (vancomycin and teicoplanin) strains have begun to emerge. [6] [20] [24] [25]

Related Research Articles

<i>Staphylococcus aureus</i> Species of Gram-positive bacterium

Staphylococcus aureus is a Gram-positive spherically shaped bacterium, a member of the Bacillota, and is a usual member of the microbiota of the body, frequently found in the upper respiratory tract and on the skin. It is often positive for catalase and nitrate reduction and is a facultative anaerobe that can grow without the need for oxygen. Although S. aureus usually acts as a commensal of the human microbiota, it can also become an opportunistic pathogen, being a common cause of skin infections including abscesses, respiratory infections such as sinusitis, and food poisoning. Pathogenic strains often promote infections by producing virulence factors such as potent protein toxins, and the expression of a cell-surface protein that binds and inactivates antibodies. S. aureus is one of the leading pathogens for deaths associated with antimicrobial resistance and the emergence of antibiotic-resistant strains, such as methicillin-resistant S. aureus (MRSA), is a worldwide problem in clinical medicine. Despite much research and development, no vaccine for S. aureus has been approved.

<span class="mw-page-title-main">Vancomycin</span> Antibiotic medication

Vancomycin is a glycopeptide antibiotic medication used to treat a number of bacterial infections. It is used intravenously as a treatment for complicated skin infections, bloodstream infections, endocarditis, bone and joint infections, and meningitis caused by methicillin-resistant Staphylococcus aureus. Blood levels may be measured to determine the correct dose. Vancomycin is also taken orally as a treatment for severe Clostridium difficile colitis. When taken orally it is poorly absorbed.

Methicillin-resistant <i>Staphylococcus aureus</i> Bacterium responsible for difficult-to-treat infections in humans

Methicillin-resistant Staphylococcus aureus (MRSA) is a group of gram-positive bacteria that are genetically distinct from other strains of Staphylococcus aureus. MRSA is responsible for several difficult-to-treat infections in humans. It caused more than 100,000 deaths worldwide attributable to antimicrobial resistance in 2019.

<span class="mw-page-title-main">Linezolid</span> Antibiotic medication

Linezolid is an antibiotic used for the treatment of infections caused by Gram-positive bacteria that are resistant to other antibiotics. Linezolid is active against most Gram-positive bacteria that cause disease, including streptococci, vancomycin-resistant enterococci (VRE), and methicillin-resistant Staphylococcus aureus (MRSA). The main uses are infections of the skin and pneumonia although it may be used for a variety of other infections including drug-resistant tuberculosis. It is used either by injection into a vein or by mouth.

<span class="mw-page-title-main">Teicoplanin</span> Pharmaceutical drug

Teicoplanin is an antibiotic used in the prophylaxis and treatment of serious infections caused by Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus and Enterococcus faecalis. It is a semisynthetic glycopeptide antibiotic with a spectrum of activity similar to vancomycin. Its mechanism of action is to inhibit bacterial cell wall synthesis.

Vancomycin-resistant <i>Staphylococcus aureus</i> Antibiotica resistant bacteria

Vancomycin-resistant Staphylococcus aureus (VRSA) are strains of Staphylococcus aureus that have acquired resistance to the glycopeptide antibiotic vancomycin. Bacteria can acquire resistant genes either by random mutation or through the transfer of DNA from one bacterium to another. Resistance genes interfere with the normal antibiotic function and allow a bacteria to grow in the presence of the antibiotic. Resistance in VRSA is conferred by the plasmid-mediated vanA gene and operon. Although VRSA infections are uncommon, VRSA is often resistant to other types of antibiotics and a potential threat to public health because treatment options are limited. VRSA is resistant to many of the standard drugs used to treat S. aureus infections. Furthermore, resistance can be transferred from one bacterium to another.

<span class="mw-page-title-main">Glycopeptide antibiotic</span> Class of antibiotic drugs

Glycopeptide antibiotics are a class of drugs of microbial origin that are composed of glycosylated cyclic or polycyclic nonribosomal peptides. Significant glycopeptide antibiotics include the anti-infective antibiotics vancomycin, teicoplanin, telavancin, ramoplanin and decaplanin, corbomycin, complestatin and the antitumor antibiotic bleomycin. Vancomycin is used if infection with methicillin-resistant Staphylococcus aureus (MRSA) is suspected.

<i>Staphylococcus saprophyticus</i> Species of bacterium

Staphylococcus saprophyticus is a Gram-positive coccus belonging to the genus Staphylococcus. S. saprophyticus is a common cause of community-acquired urinary tract infections.

Staphylococcus hominis is a coagulase-negative member of the bacterial genus Staphylococcus, consisting of Gram-positive, spherical cells in clusters. It occurs very commonly as a harmless commensal on human and animal skin and is known for producing thioalcohol compounds that contribute to body odour. Like many other coagulase-negative staphylococci, S. hominis may occasionally cause infection in patients whose immune systems are compromised, for example by chemotherapy or predisposing illness.

Vancomycin-resistant <i>Enterococcus</i> Bacterial strains of Enterococcus that are resistant to the antibiotic vancomycin

Vancomycin-resistant Enterococcus, or vancomycin-resistant enterococci (VRE), are bacterial strains of the genus Enterococcus that are resistant to the antibiotic vancomycin.

<i>Staphylococcus epidermidis</i> Species of bacterium

Staphylococcus epidermidis is a Gram-positive bacterium, and one of over 40 species belonging to the genus Staphylococcus. It is part of the normal human microbiota, typically the skin microbiota, and less commonly the mucosal microbiota and also found in marine sponges. It is a facultative anaerobic bacteria. Although S. epidermidis is not usually pathogenic, patients with compromised immune systems are at risk of developing infection. These infections are generally hospital-acquired. S. epidermidis is a particular concern for people with catheters or other surgical implants because it is known to form biofilms that grow on these devices. Being part of the normal skin microbiota, S. epidermidis is a frequent contaminant of specimens sent to the diagnostic laboratory.

<span class="mw-page-title-main">Oritavancin</span> Pharmaceutical drug

Oritavancin, sold under the brand name Orbactiv among others, is a semisynthetic glycopeptide antibiotic medication for the treatment of serious Gram-positive bacterial infections. Its chemical structure as a lipoglycopeptide is similar to vancomycin.

Lysostaphin is a Staphylococcus simulans metalloendopeptidase. It can function as a bacteriocin (antimicrobial) against Staphylococcus aureus.

mecA is a gene found in bacterial cells which allows them to be resistant to antibiotics such as methicillin, penicillin and other penicillin-like antibiotics.

<i>Staphylococcus capitis</i> Species of bacterium

Staphylococcus capitis is a coagulase-negative species (CoNS) of Staphylococcus. It is part of the normal flora of the skin of the human scalp, face, neck, scrotum, and ears and has been associated with prosthetic valve endocarditis, but is rarely associated with native valve infection.

<i>Staphylococcus</i> Genus of Gram-positive bacteria

Staphylococcus is a genus of Gram-positive bacteria in the family Staphylococcaceae from the order Bacillales. Under the microscope, they appear spherical (cocci), and form in grape-like clusters. Staphylococcus species are facultative anaerobic organisms.

SCCmec, or staphylococcal cassette chromosome mec, is a mobile genetic element of Staphylococcus bacterial species. This genetic sequence includes the mecA gene coding for resistance to the antibiotic methicillin and is the only known way for Staphylococcus strains to spread the gene in the wild by horizontal gene transfer.

Staphylococcus schleiferi is a Gram-positive, cocci-shaped bacterium of the family Staphylococcaceae. It is facultatively anaerobic, coagulase-variable, and can be readily cultured on blood agar where the bacterium tends to form opaque, non-pigmented colonies and beta (β) hemolysis. There exists two subspecies under the species S. schleiferi: Staphylococcus schleiferi subsp. schleiferi and Staphylococcus schleiferi subsp. coagulans.

Staphylococcus pseudintermedius is a gram positive coccus bacteria of the genus Staphylococcus found worldwide. It is primarily a pathogen for domestic animals, but has been known to affect humans as well. S. pseudintermedius is an opportunistic pathogen that secretes immune modulating virulence factors, has many adhesion factors, and the potential to create biofilms, all of which help to determine the pathogenicity of the bacterium. Diagnoses of Staphylococcus pseudintermedius have traditionally been made using cytology, plating, and biochemical tests. More recently, molecular technologies like MALDI-TOF, DNA hybridization and PCR have become preferred over biochemical tests for their more rapid and accurate identifications. This includes the identification and diagnosis of antibiotic resistant strains.

Kerry L. LaPlante is an American pharmacist, academic and researcher. She is a Professor of Pharmacy and the Chair of the Department of Pharmacy Practice at the University of Rhode Island, an Adjunct Professor of Medicine at Brown University, an Infectious Diseases Pharmacotherapy Specialist, and the Director of the Rhode Island Infectious Diseases Fellowship and Research Programs at the Veterans Affairs Medical Center in Providence, Rhode Island.

References

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