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PubMed1975

Membrane mutations and production of enterotoxin B and alpha hemolysin in Staphylococcus aureus.

Staphylococcus aureus strain S-6, which produces enterotoxin type B (SEB), and strain 10-275, a high toxin-producing mutant derived from S-6, display pronounced differences in dye sensitivity, osmotic stability, and bacitracin sensitivity. Such characteristics are consistent with the concept that strain 10-275 is a membrane mutant of strain S-6. Some membrane mutants of S. aureus strain 14458 exhibit about two- to three-fold increases in SEB production whereas other membrane mutants show about twofold increases in alpha-hemolysin production. It is suggested that specific and independent membrane mutations control the secretory processes resulting in the extracellular elaboration of these exoproteins.

Acriflavine↗

PubMed1971

Effect of water activity on enterotoxin B production and growth of Staphylococcus aureus.

Staphylococcus aureus C-243, an enterotoxin B-producing strain, was cultured on media adjusted to various water activity (a(w)) levels by means of two different solute systems. Total numbers and rate of growth were diminished at low a(w) levels, and enterotoxin synthesis was extremely sensitive to reduction in a(w). A reduction of a(w) from 0.99 to 0.98 in one medium and from 0.99 to 0.97 in the other medium resulted in extremely low levels of enterotoxin in spent culture media despite the attainment of high numbers of staphylococci.

Bacteriological Techniques↗

PubMed1972

Isolation by electrofocusing of two lymphocyte mitogens produced by Staphylococcus aureus.

Staphylococcus aureus strain DA352, grown in a diffusate of Todd-Hewitt broth, produced two extracellular nondialyzable lymphocyte mitogens having isoelectric points of 5.5 to 5.7 and 8.6 to 9.0. The mitogens were separable from one another by isoelectric focusing and could be isolated free of detectable amounts of other staphylococcal products by ethanol precipitation followed by isoelectric focusing. Dose-response curves with both mitogens showed a maximum per cent transformation in the range (90%+) obtained with phytohemagglutinin (PHA), a decrease of transformation with excess mitogen, and, with decreasing concentrations, a slope somewhat less steep than that obtained with PHA. Incubation with undigested or pepsin-digested pooled human gamma globulin enhanced the activity of the basic mitogen.

Ammonium Sulfate↗

PubMed1974

Isolation of an acidic surface antigen from a conventional strain of Staphylococcus aureus.

Staphylococcus aureus strain 7007, a prototype isolated from a hospital burn unit, was shown to exhibit a significant degree of resistance to ingestion by mouse polymorphonuclear leukocytes. An acidic surface antigen was isolated from strain 7007 by a combination of 10% trichloroacetic acid extraction, ion-exchange chromatography, and gel filtration. Chemical analysis indicated that the surface antigen consists of an unknown aminouronic acid and an amino sugar. Immunochemical analysis suggested that the 7007 antigen is a common feature of all the strains collected from the burn unit. No cross-reactivity was observed between the carbohydrate preparations of various hospital staphylococcal strains and the 7007 heteropolymer. These results suggested the possibility that the surface antigen of strain 7007 represents a strain- or type-specific antigen.

Agglutination Tests↗

PubMed1971

Effect of benzo(a) pyrene and piperonyl butoxide on formation of respiratory system, phospholipids, and carotenoids of Staphylococcus aureus.

Staphylococcus aureus formed an electron transport system when exponentially growing cells were aerated. Formation of the electron transport system occurred concomitantly with increases in the phospholipids and the carotenoids. The addition of piperonyl butoxide or benzo(a)pyrene at the onset of aeration (i) slowed the formation of the electron transport system, (ii) both inhibited cytochrome oxidase o synthesis and decreased its stability, (iii) simultaneously depressed the increase in total phospholipid (especially cardiolipin), and (iv) depressed the synthesis of the carotenoid rubixanthin. Benzo(a)pyrene was the more inhibitory of the two, both on the rate of synthesis of the electron transport system and on rubixanthin formation. Evidence obtained with the inhibitors suggested that inhibition of the lipid synthesis was related to the formation of the electron transport system.

Benzopyrenes↗

PubMed1975

Immunochemistry of an acidic antigen isolated from a Staphylococcus aureus.

Staphylococcus aureus, strain 7007, was shown to possess an anti-phagocytic surface antigen. This surface antigen was separated from the species-specific teichoic acid by a combination of DEAE-cellulose chromatography and Bio-Gel filtration. Chemical analyses indicated that the 7007 surface antigen consisted of aminomannuronic acid and fucosamine. Immunochemical analyses suggested that this polymer, although consisting of the same components as the staphylococcal T-antigen described by Wu and Park was, in fact, immunologically distinct from the T-antigen. Antibodies directed against the surface antigen were isolated from anti-7007 rabbit serum by affinity chromatography. These antibodies were shown to belong to the IgG class of immunoglobulins and were effective in enhancing in vitro phagocytosis of 7007 cells by polymorphonuclear leukocytes.

Acids↗

PubMed2002

The Genomic Aspect of Virulence, Sepsis, and Resistance to Killing Mechanisms in Staphylococcus aureus.

Staphylococcus aureus is widely appreciated as a pathogen, despite the fact that this microorganism is usually a benign colonizer of the host, rarely if ever causing infection. However, this bacterium, in response to changing environments, will occasionally switch from a commensal to a lethal pathogen. S. aureus uses an array of two-component signal transduction systems, winged-helix transcription proteins, and alternate sigma factor to create an intricate network of regulation in response to environmental change/stimuli. The interactions between members of this large cast of regulatory elements are beginning to be appreciated. Predicated upon recent genomic data, this review focuses on how this regulatory apparatus functions to control the expression of the multitude of virulence factors this "Jekyl and Hyde" organism produces.

Journal Article↗

PubMed1984

Skin and skin structure infections in the patient at risk: carrier state of Staphylococcus aureus.

Staphylococcus aureus is a ubiquitous organism that is normally carried on the skin and body surfaces of man. The nares are sites frequently colonized, and patients and hospital personnel represent the major source of infection. The occurrence of staphylococcal infection depends on the availability of staphylococci and the host resistance to infection. Factors that influence the carrier rate of S. aureus include minimal colonizing dose, effects of antimicrobial therapy, disinfectants in the environment, coincidental respiratory infections, possible effect of immune factors, duration of hospital stay, and regular needle injections. Certain patients such as drug abusers, patients with diabetes, and patients with chronic renal failure are at high risk of S. aureus infections. although underlying immune deficiencies are present, increased carrier rate also might be related to regular needle use, as shown among allergy patients. The significance of carrier state has been defined in outbreaks in hospital nurseries, postoperative patients, and systemic infections such as endocarditis in the drug abuser, the toxic shock syndrome, and dermatologic infections.

Carrier State↗

PubMed2000

Contribution of clumping factor B to pathogenesis of experimental endocarditis due to Staphylococcus aureus.

Staphylococcus aureus Newman with an insertion mutation in clfB, the gene encoding clumping factor B, only marginally decreased infection rate (P>0.05) in rats with experimental endocarditis. In contrast, clfB complementation on a multicopy plasmid significantly increased infectivity (P<0.05) over the deleted mutants. Although clfB could affect endovascular infection, its importance in experimental endocarditis was limited.

Adhesins, Bacterial↗

PubMed2023

Teicoplanin associated gene tcaA inactivation increases persister cell formation in Staphylococcus aureus.

Staphylococcus aureus is part of normal human flora and is widely associated with hospital-acquired bacteremia. S. aureus has shown a diverse array of resistance to environmental stresses and antibiotics. Methicillin-resistant S. aureus (MRSA) is on the high priority list of new antibiotics discovery and glycopeptides are considered the last drug of choice against MRSA. S. aureus has developed resistance against glycopeptides and the emergence of vancomycin-intermediate-resistant, vancomycin-resistant, and teicoplanin-resistant strains is globally reported. Teicoplanin-associated genes tcaR-tcaA-tcaB (tcaRAB) is known as the S. aureus glycopeptide resistance operon that is associated with glycopeptide resistance. Here, for the first time, the role of tcaRAB in S. aureus persister cells formation, and ΔtcaA dependent persisters' ability to resuscitate the bacterial population was explored. We recovered a clinical strain of MRSA from a COVID-19 patient which showed a high level of resistance to teicoplanin, vancomycin, and methicillin. Whole genome RNA sequencing revealed that the tcaRAB operon expression was altered followed by high expression of glyS and sgtB. The RNA-seq data revealed a significant decrease in tcaA (p = 0.008) and tcaB (p = 0.04) expression while tcaR was not significantly altered. We knocked down tcaA, tcaB, and tcaR using CRISPR-dCas9 and the results showed that when tcaA was suppressed by dCas9, a significant increase was witnessed in persister cells while tcaB suppression did not induce persistence. The results were further evaluated by creating a tcaA mutant that showed ΔtcaA formed a significant increase in persisters in comparison to the wild type. Based on our findings, we concluded that tcaA is the gene that increases persister cells and glycopeptide resistance and could be a potential therapeutic target in S. aureus.

MRSA↗

PubMed1998

The Staphylococcus aureus and Staphylococcus epidermidis transferrin-binding proteins are expressed in vivo during infection.

Staphylococci express a 42 kDa cell-wall-associated protein which functions as a receptor for the mammalian iron-binding glycoprotein transferrin. To determine whether this transferrin-binding protein (TBP) is expressed during infection, Staphylococcus aureus and Staphylococcus epidermidis were grown in vivo in chambers implanted intraperitoneally in rats. SDS-PAGE and Western blotting of cell wall proteins prepared from staphylococci recovered directly from the chambers revealed the presence of both the TBP and bacterial-surface-associated rat transferrin. To obtain evidence for the in vivo expression of the staphylococcal TBPs in humans, sera and human peritoneal dialysate (HPD) from non-infected patients undergoing continuous ambulatory peritoneal dialysis (CAPD) and sera from healthy human volunteers were screened for anti-TBP antibodies. Western immunoblots revealed that three out of ten samples from the latter group, seven out of ten HPD samples and ten of ten CAPD patient serum samples contained antibodies to the TBP of both S. aureus and S. epidermidis. To gain further insights into the appearance of TBP antibodies, HPD samples were collected over time from CAPD patients whose HPD samples taken immediately after catheter insertion lacked anti-TBP antibodies. In two of these patients, each of whom experienced an episode of peritonitis due to S. epidermidis or Staphylococcus hominis, antibodies to the TBP appeared in the HPD collected immediately post-infection. To determine whether such TBP antibodies were capable of blocking interactions between transferrin and its staphylococcal receptor, HPD immunoglobulin fractions were purified using protein A-Sepharose beads. In competition assays, these immunoglobulins blocked the binding of 125I-labelled transferrin both to whole bacteria and to the isolated 42 kDa TBPs of S. aureus and S. epidermidis. These provide evidence to show that staphylococcal TBPs are expressed in vivo during infection.

Animals↗

PubMed1996

Comparison of the beta-toxins from Staphylococcus aureus and Staphylococcus intermedius.

The beta-toxins produced by Staphylococcus aureus and Staphylococcus intermedius were purified to homogeneity from culture supernatants. Although the toxin from S. aureus has been throughly studied, less is known about its unique counterpart from S. intermedius. This is the first reported purification and analysis of the S. intermedius beta-toxin. Both toxins have similar enzymatic properties, belong to the class of neutral sphingomyelinases C, and have a high specificity for sphingomyelin. They also hydrolyze lysophosphatidylcholine at a much slower rate, but have no activity toward phosphatidylcholine, phosphatidylethanolamine, or phosphatidylserine. The kinetic parameters determined for both proteins (apparent Km 1.4 mM, Vmax 100 mmol/min/microg protein) are identical. Despite these similarities, the size and amino acid composition of the two beta-toxins differ. Molecular mass values, determined by electrophoresis and gel filtration, indicate that the both enzymes are single polypeptides. The decrease in sphingomyelinase activity of S. aureus beta-toxin upon pretreatment with dithiothreitol (DTT) indicates the presence of a disulfide bond in the protein. In contrast, DTT has no effect on the enzymatic activity of S. intermedius beta-toxin. This observation is consistent with the absence of detectable cysteine residue in the protein. N-terminal amino acid sequences determined for the first 19 residues of both beta-toxins also differ, only nine of the first 19 residues are identical. Further evidence that the two proteins differ was obtained by immunological analysis which demonstrated crossreactivity but a lack of identity.

Amino Acid Sequence↗

PubMed1980

Identity and interspecific transfer of gentamicin-resistance plasmids in Staphylococcus aureus and Staphylococcus epidermidis.

The hypothesis that emergence of gentamicin-resistant strains of Staphylococcus aureus and Staphylococcus epidermidis in a neonatal special care nursery was the result of transfer of a single plasmid between these two species was examined. In experiments with mixtures of staphylococci, either in mixed cultures or on human skin, isolates of S. aureus and S. epidermidis transferred their gentamicin-resistance plasmids both intra- and interspecifically. By electron microscopy, the molecular masses of the plasmids from S. aureus and S. epidermidis were the same, 12.2 +/- 0.36 (standard deviation) and 12.3 +/- 0.56 megadaltons, respectively. Restriction endonuclease analysis of the plasmids from five isolates of S. aureus and two isolates of S. epidermidis, with use of the enzymes HaeIII, EcoRI, XbaI, and HindIII, showed no differences in the digestion patterns of the seven gentamicin-resistance plasmids. The results supported the hypothesis that plasmid transfer between S. aureus and S. epidermidis occurs in nature.

Conjugation, Genetic↗

PubMed1983

Conjugational transfer of gentamicin resistance plasmids intra- and interspecifically in Staphylococcus aureus and Staphylococcus epidermidis.

We have previously reported the transfer of gentamicin resistance (Gmr) plasmids in a mixed culture inter- and intraspecifically between strains of Staphylococcus aureus and Staphylococcus epidermidis isolated at Michael Reese Hospital (Jaffe et al., Antimicrob. Agents Chemother. 21:773-779, 1982). We have now shown that representatives of these plasmids were transferred between apparently nonlysogenic strains of S. aureus either in mixed culture in broth or by filter-mating on agar medium. The mechanism of transfer appeared to be conjugation. A transferable Gmr plasmid (pSH8) mobilized or cotransferred a tetracycline R-plasmid and a chloramphenicol R-plasmid that were not independently transferable. The transfer of Gmr plasmids was accompanied by a high incidence of deletion mutations with varied loss of plasmid resistance determinants and, with some mutants, loss of the ability to effect self-transfer. Restriction endonuclease digestion of pSH8 and its deletion mutants made it possible to assign the property of self-transfer to a specific segment of the pSH8 genome and provided the basis for a physical and genetic map of that plasmid. Similar Gmr plasmids from S. aureus strains isolated in locations remote from Michael Reese Hospital had resistance determinants and transfer properties comparable to those of pSH8. Our observations provide evidence for the conjugal transfer of some staphylococcal plasmids, apparently independent of the presence of phage. This mechanism may be of significance in the intra- and interspecific dissemination of resistance to aminoglycosides and other antibiotics in Staphylococcus spp.

Chromosome Mapping↗

PubMed1988

Staphylococcal phosphoenolpyruvate-dependent phosphotransferase system: purification and characterization of the mannitol-specific enzyme IIImtl of Staphylococcus aureus and Staphylococcus carnosus and homology with the enzyme IImtl of Escherichia coli.

Enzyme IIImtl is part of the mannitol phosphotransferase system of Staphylococcus aureus and Staphylococcus carnosus and is phosphorylated by phosphoenolpyruvate in a reaction sequence requiring enzyme I (phosphoenolpyruvate-protein phosphotransferase) and the histidine-containing protein HPr. In this paper, we report the isolation of IIImtl from both S. aureus and S. carnosus and the characterization of the active center. After phosphorylation of IIImtl with [32P]PEP, enzyme I, and HPr, the phosphorylated protein was cleaved with endoproteinase Glu(C). The amino acid sequence of the S. aureus peptide carrying the phosphoryl group was found to be Gln-Val-Val-Ser-Thr-Phe-Met-Gly-Asn-Gly-Leu-Ala-Ile-Pro-His-Gly-Thr-Asp- Asp. The corresponding peptide from S. carnosus shows an equal sequence except that the first residue is Ala instead of Gln. These peptides both contain a single histidyl residue which we assume to carry the phosphoryl group. All proteins of the PTS so far investigated indeed carry the phosphoryl group attached to a histidyl residue. According to sodium dodecyl sulfate gels, the molecular weight of the IIImtl proteins was found to be 15,000. We have also determined the N-terminal sequence of both proteins. Comparison of the IIImtl peptide sequences and the C-terminal part of the enzyme IImtl of Escherichia coli reveals considerable sequence homology, which supports the suggestion that IImtl of E. coli is a fusion protein of a soluble III protein with a membrane-bound enzyme II. In particular, the homology of the active-center peptide of IIImtl of S. aureus and S. carnosus with the enzyme IImtl of E. coli allows one to predict the N-3 histidine phosphorylation site within the E. coli enzyme.

Amino Acid Sequence↗

PubMed1989

Influence of magnesium concentration on production of exoprotein and beta-lactamase by Staphylococcus aureus and Staphylococcus hemolyticus.

Earlier investigations demonstrated that production and secretion of toxic shock syndrome toxin-1 (TSST-1) and total exoprotein by strains of Staphylococcus aureus were maximal when magnesium ion was limiting and diminished when the concentration of magnesium increased. This investigation studied the influence of magnesium concentration on production of total exoprotein and beta-lactamase by strains of S. aureus and Staphylococcus hemolyticus, isolated from the genital tracts of women. These strains were resistant to penicillins. Each organism was incubated in chemically defined medium with various concentrations of magnesium, and total exoprotein production and beta-lactamase activity in supernatants were determined. In all strains, total exoprotein production and beta-lactamase activity per bacterial cell were markedly increased in the presence of low concentrations of magnesium. When the concentration of magnesium was elevated, production of total exoprotein and beta-lactamase was decreased. Therefore, magnesium-deficient strains of S. aureus and S. hemolyticus may secrete more exoproteins and be more resistant to beta-lactam drugs than when magnesium is not limiting.

Bacterial Proteins↗

PubMed1992

In vitro activity of sparfloxacin and three other fluoroquinolones against methicillin-resistant Staphylococcus aureus and Staphylococcus epidermidis.

Fluoroquinolones are variably active against methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant Staphylococcus epidermidis (MRSE). The purpose of this study was to test the in vitro susceptibility of 50 isolates each of MRSA and MRSE to four of the new fluoroquinolones--sparfloxacin, ciprofloxacin, ofloxacin and norfloxacin--and to see if resistance could be induced in five susceptible strains of each species by serial passages with increasing concentrations of drug. A standard microdilution technique was used to determine minimal inhibitory concentrations (MICs) and minimal bactericidal concentrations (MBCs) of each drug for each isolate. Agar dilution plates were also prepared containing concentrations of drug varying from one-half of the reported MIC to 128 times the reported MIC, and microorganisms persisting were serially passaged. Initially, 98% of the strains of MRSA were susceptible to the fluoroquinolones. MBCs were essentially identical to MICs. Similarly, 96% of the strains of MRSE were susceptible. Following exposure to increasing concentrations of each fluoroquinolone, resistance appeared to emerge less rapidly to sparfloxacin and ofloxacin than to norfloxacin and ciprofloxacin.

Anti-Infective Agents↗

PubMed1992

Frequency and transferability of trimethoprim and sulfonamide resistance in methicillin-resistant Staphylococcus aureus and Staphylococcus epidermidis.

A total of 374 Staphylococcus aureus and 126 Staphylococcus epidermidis strains from 14 countries were studied for their resistance to methicillin, trimethoprim (Tp) and sulfonamides (Su), alone and combined (TpSu). The frequency of resistance to Tp, Su and TpSu was much higher in methicillin-resistant S. epidermidis (MRSE) than in methicillin-resistant S. aureus (MRSA). Considerable differences, however, existed in isolates from different countries. Resistance to Tp, Su or TpSu in MRSA was low or absent in isolates from Switzerland, Spain, Japan, Mexico, Argentina and Chile, but high in isolates from Germany and Brazil. High level Tp resistance mostly resided on large plasmids. It could be transferred in 17 out of 97 strains. Su resistance was never cotransferred. Strains cured of their large Tp resistance plasmids remained Su-resistant, which suggests a chromosomal location of Su resistance.

Anti-Bacterial Agents↗