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PubMed1977

Function of cell wall teichoic acid in thermally injured Staphylococcus aureus.

Thermally injured cells of Staphylococcus aureus lack the ability to grow on tryptic soy agar containing 7.5% NaCl. This injury phenomenon was examined in three strains of S. aureus: MF-31; H (Str); and, isolated from H (Str), 52A5, a mutant which lacks teichoic acid in the cell wall. Temperatures for sublethal heat treatment were selected to produce maximum injury with minimum death for each strain. Examination of isolated cell walls showed that magnesium was lost from the wall during heating, and that the degree of cell injury was accentuated when magnesium ions were either removed from or made unavailable to the cell. S. aureus 52A5 was more heat sensitive than its parent strain. Cells containing higher levels of wall teichoic acid generally showed less injury than normal cells. Cells with the weaker cation-binding polymer, teichuronic acid, in the cell wall generally showed greater injury. These data suggest that cell wall teichoic acid of S. aureus aids in the survival of the cell by the maintenance of an accessible surface pool of magnesium.

Calcium Chloride↗

PubMed1990

Emergence of teicoplanin resistance during therapy of Staphylococcus aureus endocarditis.

Serial isolates of Staphylococcus aureus showing two- to eightfold increases in teicoplanin minimum inhibitory concentrations (MICs) and twofold or less increases in MICs of other glycopeptides were recovered from the blood of a patient with endocarditis in whom drug therapy was unsuccessful. Comparable resistance emerged during teicoplanin treatment of rabbits with endocarditis caused by the original susceptible parent strain. For the parent strain, spontaneous resistance to teicoplanin at concentrations of 2-10 times the MIC was detected in vitro at frequencies of 10(-7) to 10(-9). Similar results were found for isolates of S. aureus from other geographic locations. Resistance was constitutive and not plasmid mediated, and its acquisition was not associated with changes in cytoplasmic membrane proteins. Teicoplanin was less effective than vancomycin at inhibiting peptidoglycan synthesis in resistant strains, suggesting that there is differential interference with the access of teicoplanin to or interaction with its target(s). Alternatively, teicoplanin and vancomycin may differ in some detail(s) of their mechanism of action against S. aureus.

Adult↗

PubMed1998

Association of borderline oxacillin-susceptible strains of Staphylococcus aureus with surgical wound infections.

Staphylococcus aureus isolates which produce type A staphylococcal beta-lactamase have been associated with wound infections complicating the use of cefazolin prophylaxis in surgery. To further evaluate this finding, 215 wound isolates from 14 cities in the United States were characterized by antimicrobial susceptibility and beta-lactamase type and correlated with the preoperative prophylactic regimen. Borderline-susceptible S. aureus isolates of phage group 5 (BSSA-5), which produce large amounts of type A beta-lactamase and exhibit borderline susceptibility to oxacillin, comprised a greater percentage of the 120 wound isolates associated with cefazolin prophylaxis than they did of the 95 isolates associated with other prophylactic regimens (25% versus 12.6%, respectively; P < 0.05). In contrast, methicillin-resistant S. aureus isolates were distributed evenly between the two groups (8.3% versus 11.6%, respectively). In vitro assays demonstrated that cefazolin was hydrolyzed faster by BSSA-5 strains than by other beta-lactamase-producing, methicillin-susceptible strains (1.54 versus 0.50 microg/min/10(8) CFU, respectively; P < 0.0001). These data demonstrate that BSSA-5 strains are a distinct subpopulation of methicillin-susceptible S. aureus which frequently cause deep surgical wound infections. Cefazolin use in prophylaxis is a risk factor for BSSA-5 infection.

Cefazolin↗

PubMed2025

Genome-wide analysis of fitness determinants of Staphylococcus aureus during growth in milk.

Staphylococcus aureus is a major concern in the dairy industry due to its significance as a pathogen causing bovine mastitis as well as a source of food poisoning. The nutrient-rich milk environment supports bacterial growth, but the specific genetic determinants that facilitate S. aureus proliferation and persistence in milk are poorly understood. In this study, we conducted a genome-wide CRISPR interference sequencing (CRISPRi-seq) screen with the laboratory strain S. aureus NCTC8325-4, to identify fitness determinants essential for S. aureus growth and survival in milk. We identified 282 milk-essential genes, including those with key roles in DNA replication, protein synthesis, and metabolism. Comparative analysis with brain heart infusion (BHI) as growth medium, revealed 79 genes with differential fitness, highlighting specific adaptations required for growth in milk. Notably, we found that purine biosynthesis, folate cycle pathways, and metal acquisition were particularly important in this environment. Based on this, we further demonstrate that S. aureus is more sensitive to the folate inhibitors trimethoprim-sulfamethoxazole (TMP-SMX) in milk and identify several genes whose knockdown results in hypersensitivity to TMP-SMX in milk. Additionally, our analysis showed a relatively reduced importance of cell wall components, such as teichoic acids, for S. aureus fitness in milk, which is also reflected in reduced efficiency of antimicrobials targeting teichoic acids. Together, these findings provide new insights into the genetic basis of S. aureus fitness and antibiotic susceptibility in milk, offering directions for novel treatment strategies against bovine mastitis.

Animals↗

PubMed2006

Daptomycin versus standard therapy for bacteremia and endocarditis caused by Staphylococcus aureus.

BACKGROUND: Alternative therapies for Staphylococcus aureus bacteremia and endocarditis are needed. METHODS: We randomly assigned 124 patients with S. aureus bacteremia with or without endocarditis to receive 6 mg of daptomycin intravenously per kilogram of body weight daily and 122 to receive initial low-dose gentamicin plus either an antistaphylococcal penicillin or vancomycin. The primary efficacy end point was treatment success 42 days after the end of therapy. RESULTS: Forty-two days after the end of therapy in the modified intention-to-treat analysis, a successful outcome was documented for 53 of 120 patients who received daptomycin as compared with 48 of 115 patients who received standard therapy (44.2 percent vs. 41.7 percent; absolute difference, 2.4 percent; 95 percent confidence interval, -10.2 to 15.1 percent). Our results met prespecified criteria for the noninferiority of daptomycin. The success rates were similar in subgroups of patients with complicated bacteremia, right-sided endocarditis, and methicillin-resistant S. aureus. Daptomycin therapy was associated with a higher rate of microbiologic failure than was standard therapy (19 vs. 11 patients, P=0.17). In 6 of the 19 patients with microbiologic failure in the daptomycin group, isolates with reduced susceptibility to daptomycin emerged; similarly, a reduced susceptibility to vancomycin was noted in isolates from patients treated with vancomycin. As compared with daptomycin therapy, standard therapy was associated with a nonsignificantly higher rate of adverse events that led to treatment failure due to the discontinuation of therapy (17 vs. 8, P=0.06). Clinically significant renal dysfunction occurred in 11.0 percent of patients who received daptomycin and in 26.3 percent of patients who received standard therapy (P=0.004). CONCLUSIONS: Daptomycin (6 mg per kilogram daily) is not inferior to standard therapy for S. aureus bacteremia and right-sided endocarditis. (ClinicalTrials.gov number, NCT00093067 [ClinicalTrials.gov].).

Adult↗

PubMed1990

Effect of Cd2+ on ATP synthesis coupled to electron transfer in cadmium-resistant and -sensitive Staphylococcus aureus.

In the Cd2(+)-resistant Staphylococcus aureus 17810R which contains the plasmid-coded Cd2+ efflux system, accumulation of Cd2+ was highly reduced. Consequently, neither respiration nor ATP synthesis coupled to electron transfer were inhibited. The plasmidless S. aureus strain 17810S accumulated Cd2+ via the Mn2+ porter down the membrane potential (delta phi) which resulted in inhibition of respiration and of ATP synthesis.

Adenosine Triphosphate↗

PubMed2006

Gold nanoparticle-based immunochromatographic test for identification of Staphylococcus aureus from clinical specimens.

BACKGROUND: Staphylococcus aureus is one of the most important human pathogens, causing both nosocomial and community-acquired infections. Therefore, a method for rapidly detecting for S. aureus would be useful. We describe an analytical system of immunochromatographic assay based on gold nanoparticles developed for the detection of S. aureus in patient specimen. METHODS: The assay was in the sandwich format, using anti-protein A IgG with 2 distinct specificities. One anti-protein A IgG was immobilized in a defined detection zone on a porous nitrocellulose membrane, while the other anti-protein A IgG was conjugated with gold nanoparticles. The mixture was then passed along the porous membrane by capillary action past the anti-protein A IgG in the detection zone, binding the particles that to which surface protein A was already bound to their surface, yielding a red color. RESULTS: The sensitivity and specificity in the immunochromatographic test were 100% and 94.7-100% for 130 S. aureus strains and 36 non-S. aureus strains, respectively. The results were comparable to the conventional coagulase test and latex agglutination test of different bacteria. CONCLUSION: This method may be useful for analyzing S. aureus in patient specimen. It was quick, easy to perform, and with a long shelf life at room temperature.

Antibodies↗

PubMed1981

Further studies on antigen variation in Staphylococcus aureus.

The plating of successive Staphylococcus aureus subcultures of daily transfers proved that discontinuous variation resembling a genetic mutation and selective outgrowth of the variant are responsible for antigen variation. Every subculture of S. aureus, when repeatedly transferred, contained a mixture of cells with original antigen 17 (or 13) and final antigen 1 (or 3) that are relevant for research, serological diagnosis, and epidemiological study of staphylococcal diseases.

Antigens, Bacterial↗

PubMed2006

Panton-Valentine leukocidin genes are associated with enhanced inflammatory response and local disease in acute hematogenous Staphylococcus aureus osteomyelitis in children.

BACKGROUND: Staphylococcus aureus strains carrying the genes encoding Panton-Valentine leukocidin (pvl-positive [pvl+]) are associated with more febrile days and higher complication rates of osteomyelitis in children than are pvl-negative (pvl-) strains. OBJECTIVES: Selected clinical, laboratory, and radiographic findings in children with osteomyelitis caused by pvl+ and pvl- S aureus strains were compared. METHODS: The demographics, selected clinical features, laboratory values, and radiographic findings of children with community-acquired S aureus osteomyelitis prospectively identified at Texas Children's Hospital between August 2001 and July 2004 were reviewed. Polymerase chain reaction was performed to detect the genes for pvl (luk-S-PV and luk-F-PV) and fibronectin-binding protein (fnbB) in S aureus isolates. Chi2, 2-sample t test, and multiple logistic regression were used for statistical analysis. RESULTS: Methicillin-susceptible and methicillin-resistant S aureus (MSSA and MRSA, respectively) caused osteomyelitis in 33 and 56 children, respectively. Twenty-six isolates were pvl- (26 MSSA), 59 were pvl+ (3 MSSA, 56 MRSA), and 4 were not available for analysis (4 MSSA). On univariate analysis, patients with pvl+ S aureus isolates had significantly higher erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) level both at presentation and as a maximum value during hospitalization and were more likely to have a blood culture positive for S aureus during their admission. Patients with pvl+ S aureus isolates were significantly more likely to have concomitant myositis or pyomyositis compared with patients with pvl- S aureus isolates on MRI. In a multivariate analysis pvl remained significantly associated with ESR and CRP levels at presentation and blood culture positive for S aureus. pvl+ status and younger age were associated with myositis on MRI. CONCLUSIONS: Osteomyelitis caused by pvl+ S aureus strains were associated with more severe local disease and a greater systemic inflammatory response compared with osteomyelitis caused by pvl- S aureus.

Acute Disease↗

PubMed2004

The role of B cell CD22 expression in Staphylococcus aureus arthritis and sepsis.

Severe Staphylococcus aureus infections give rise to a pronounced antigen-specific and polyclonal B cell response with elevated serum immunoglobulin levels. However, it has been difficult to correlate the antibody levels with the clinical outcome of sepsis and/or arthritis concerning both protection and pathogenic aspects. Earlier studies have shown that macrophages and neutrophils are of great importance for bacterial clearance. However, deletion of the complete B cell compartment affected neither S. aureus-induced arthritis nor survival. MZ B cells are believed to be of importance for clearance of blood-borne antigens and have been implicated in protection against S. aureus infections. CD22 is a B-cell-specific inhibitory receptor binding to alpha2,6-linked sialic acids, and deficiency in CD22 leads to a 75% reduction of the MZ B cell compartment. CD22-/- mice and congeneic controls were inoculated intravenously with an arthritogenic dose of live S. aureus. No differences between the groups were detected regarding frequency and severity of arthritis, survival, bacterial clearance, or induction of inflammatory response. This study shows explicitly that a reduced MZ B cell compartment in the absence of CD22 expression does not interfere with the inflammatory response during S. aureus infection.

Animals↗

PubMed1995

In-vitro and in-vivo selection of Staphylococcus aureus mutants resistant to ciprofloxacin.

Staphylococcus aureus mutants resistant to ciprofloxacin were selected both in vitro and in vivo. In-vitro selection was achieved by incubating two strains of S. aureus (MICs of ciprofloxacin of 0.5 and 4 mg/L respectively) in the presence of ciprofloxacin in concentrations equivalent to 1/2 x MIC for 24 h and isolating the mutants on agar containing the quinolone at 1, 2 or 5 x MIC. Stably-resistant mutants of both strains were isolated, although the frequency of mutation of the susceptible strain was higher than that of the resistant strain. A murine subcutaneous abscess model was used for in-vivo selection. Mice which had been infected with a ciprofloxacin-susceptible strain of S. aureus were treated for 24 h with ciprofloxacin in a dosage which yielded concentrations in the abscess cavity equivalent to 1/2 or 1 x MIC for the pathogen. Additional groups of infected mice received ciprofloxacin for varying periods in a dosage which produced concentrations at the site of infection equivalent to 1/2 x MIC. Stably-resistant mutants were isolated from the abscesses, the number of mice from which mutants were isolated and the mutational frequency being inversely proportional to the dosage of ciprofloxacin administered and the duration of treatment. The results of this study confirm that, in the treatment of patients with infections caused by S. aureus, the dosage of ciprofloxacin should be adequate to ensure inhibitory concentrations at the site of infection.

Abscess↗

PubMed1999

Mechanisms of Staphylococcus aureus invasion of cultured osteoblasts.

Staphylococcus aureus is a bacterial pathogen causing approximately 80% of all cases of human osteomyelitis. This bacterium can adhere to and become internalized by osteoblasts and previous studies indicate that osteoblasts are active in the internalization process. In the current study, we examined the roles of microfilaments, microtubules and clathrin-dependent receptor-mediated endocytosis in the internalization of S. aureus by MC3T3-E1 mouse osteoblast cells. Microfilament and microtubule polymerization was inhibited with cytochalasin D and colchicine. Clathrin-coated pit formation was examined by using the transaminase inhibitor, monodanslycadaverine. The results of this study indicate that mouse osteoblasts utilize actin microfilaments, microtubules and clathrin-coated pits in the internalization of S. aureus; however, microfilaments seem to play the most significant role in the invasion process.

Animals↗

PubMed2000

A new two-component regulatory system involved in adhesion, autolysis, and extracellular proteolytic activity of Staphylococcus aureus.

A transposition mutant of Staphylococcus aureus was selected from the parent strain MT23142, a derivative of strain 8325. The site of transposition was near the 5' terminus of the gene arlS. ArlS exhibits strong similarities with histidine protein kinases. Sequence analysis suggested that arlS forms an operon with upstream gene arlR. The predicted product of arlR is a member of the OmpR-PhoB family of response regulators. The arlS mutant formed a biofilm on a polystyrene surface unlike the parent strain and the complemented mutant. Biofilm formation was associated with increased primary adherence to polystyrene, whereas cellular adhesion was only slightly decreased. In addition, the arlS mutant exhibited increased autolysis and altered peptidoglycan hydrolase activity compared to the parental strain and to the complemented mutant. As it has been shown for coagulase-negative staphylococci that some autolysins are able to bind polymer surfaces, these data suggest that the two-component regulatory system ArlS-ArlR may control attachment to polymer surfaces by affecting secreted peptidoglycan hydrolase activity. Finally, the arlS mutant showed a dramatic decrease of extracellular proteolytic activity, including serine protease activity, in comparison to the wild-type strain and the complemented mutant, and cells grown in the presence of phenylmethylsulfonyl fluoride (a serine protease inhibitor) showed an increased autolysin activity. Since the locus arlR-arlS strikingly modifies extracellular proteolytic activity, this locus might also be involved in the virulence of S. aureus.

Amino Acid Sequence↗

PubMed2003

[Cell wall components of gramicidin S resistant Staphylococcus aureus].

Comparative study of two staphylococcus aureus 209P strains--resistant and susceptible to gramicidin S demonstrated that peptidoglycanes of two strains differ by ratio glycine/serine at peptide bridges. Besides peptidoglycanes significantly differ by amidation of alfa-carboxyles of glutamic acid in muropeptide. This peptidoglycane modification of resistant cells along with enhanced content of etherized D-alanine in teichoic acid provides lower negative charge of cell wall components. It may influence the cell wall ability to react with positively charged gramicidin molecules. It was shown that isolated cell walls and peptidoglycane of resistant cells binds significantly less gramicidin than cell walls and peptodoglyce of susceptable cells. Simultaneous determination of gramicidin binding by intact S. aureus cells and their killing revealed that lower ability of resistant cells to bind gramicidin is significant but not critical factor of gramicidin resistance.

Anti-Bacterial Agents↗

PubMed1995

Cloning, nucleotide sequence determination and expression of the Staphylococcus aureus hyaluronate lyase gene.

The Staphylococcus aureus 8325-4 hyaluronate lyase gene (hysA) was identified after detecting hyaluronate lyase activity expressed by phages from a genomic library. The hysA open reading frame, capable of encoding a protein of 91 980 Da, was identified by Tn5 mutagenesis and nucleotide sequencing. HysA shares 35 and 36% amino acid sequence identity with group B streptococcal hyaluronate lyase and pneumococcal hyaluronidase, respectively. A 94-kDa protein was expressed in Escherichia coli minicells, a result consistent with the coding capacity of hysA. Identification of the S. aureus 8325-4 hyaluronate lyase gene will allow the regulation of this putative virulence determinant to be studied.

Amino Acid Sequence↗

PubMed1983

Activation of purified human plasma prekallikrein triggered by cell wall fractions of Escherichia coli and Staphylococcus aureus.

Whether Escherichia coli and Staphylococcus aureus cell wall fractions can trigger the activation of prekallikrein was investigated in a mixture of purified human factor XII, prekallikrein, and high-relative-molecular-weight (Mr) kininogen. After exposure for 30 min to bacterial preparations (0.02-5 mg/ml) at 0 C, lallikrein amidolytic activity was expressed as a percentage of the optimal activation of prekallikrein induced by dextran sulfate. Lipopolysaccharide (LPS) fractions of five E coli strains and lipid A of E coli O111B4 induced 50%-90% optimal activity. However, the polysaccharide fraction induced less than 5% activity. Peptidoglycan and teichoic acid of S aureus induced 70%-100% optimal activity at 5 mg/ml, but protein A did not generate activity. No activation of prekallikrein occurred in the absence of factor XII. Thus, LPS and lipid A of E coli and peptidoglycan and teichoic acid of S aureus can generate kallikrein amidolytic activity in a mixture of purified factor XII, prekallikrein, and high-Mr kininogen.

Cell Wall↗

PubMed1995

Possible receptor for exfoliative toxins produced by Staphylococcus hyicus and Staphylococcus aureus.

Exfoliative toxin produced by Staphylococcus hyicus bound to the GM4-like glycolipid extracted from the skin of 1-day-old chickens but did not bind to glycolipid from adult chickens or suckling mice. Exfoliative toxin produced by Staphylococcus aureus bound to the GM4-like glycolipid extracted from the skin of suckling mice but not to glycolipid from 1-day-old or adult chickens. S. hyicus and S. aureus exfoliative toxins lost their toxicity by preincubation with GM4-like glycolipid from 1-day-old chickens and suckling mice, respectively.

Animals↗

PubMed2006

Multiplex PCR assay for the detection of high virulence rabbit Staphylococcus aureus strains.

High virulence rabbit Staphylococcus aureus strains, which are clonal in origin, are responsible for the spread of chronic staphylococcosis at the rabbit flock level. The aim of the present study was to develop a multiplex PCR assay that can be used for the identification of these high virulence strains. Two targets of the assay were the bbp and the selm genes, which have recently been shown to occur specifically in high virulence isolates. A third target was a sequence designated "flank", which was derived from a previously generated high virulence specific RAPD pattern. Furthermore, the femA gene, which is specific for S. aureus, was incorporated in order to avoid false negative results due to insufficient DNA preparation. The multiplex PCR was successful at differentiating the 26 typical high virulence and 50 low virulence rabbit S. aureus strains incorporated in the present study. Therefore it is useful for the initial screening of newly acquired breeding stock, in order to prevent the intake of high virulence strains in rabbitries.

Animals↗