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PubMed2003

Clinical identifiers of complicated Staphylococcus aureus bacteremia.

BACKGROUND: Complications of Staphylococcus aureus bacteremia (SAB) are often difficult to identify. The ability to accurately predict the likelihood of these complications would impact patient management. This investigation sought to define readily available clinical characteristics that could help identify patients at risk for complicated SAB. METHODS: A prospective, observational cohort study was conducted from September 1994 through December 1999. Patients were followed up for 12 weeks after the initial positive blood culture result. The primary end point was complicated SAB (attributable mortality, complicated infection, embolic stroke, or recurrent S aureus infection during the 12-week follow-up period). The predictive model was validated using bootstrap resampling. RESULTS: Complicated SAB was present in 43% of 724 consecutive adult hospitalized patients identified during the study period. The full predictive model had a high discriminative ability (bootstrap-corrected c index, 0.78). The strongest predictor of complicated SAB was a positive follow-up blood culture result at 48 to 96 hours. A scoring system based on the presence or absence of 4 risk factors (community acquisition, skin examination findings suggesting acute systemic infection, persistent fever at 72 hours, and positive follow-up blood culture results at 48-96 hours) accurately identified complicated SAB (bootstrap-corrected c index, 0.76). CONCLUSION: Readily available clinical variables can help identify patients at risk for complicated SAB.

Adult↗
PubMed1979

Activation of human lymphocyte subpopulations by protein A from Staphylococcus aureus bacteria.

Cowan I strain Staphylococcus aureus bacteria were found to be mitogenic for human peripheral and cord blood lymphocytes. Experiments with lymphocyte supopulations otained by nylon wool filtration and/or E-rosette separation revealed that T-lymphocytes are the main target cells, whereas isolated B cells did not respond significantly. Further experiments suggested that B cells could be activated in the presence of mitomycin-treated T cells. Null cell-enriched lymphocyte suspensions could be stimulated by Con A but not by the bacteria or by PHA.

B-Lymphocytes↗
PubMed1999

Methicillin-Resistant Staphylococcus aureus Infections.

Methicillin-resistant Staphylococcus aureus (MRSA) has continued to spread and cause serious nosocomial infections. Failure to control MRSA may result in higher rates of use of glycopeptides, which may, in turn, lead to higher rates of glycopeptide resistance. Resistance to glycopeptides has recently begun to appear in S. aureus. Transfer of glycopeptide-resistance genes from enterococci to S. aureus has been documented in laboratory experiments but has not yet been found in clinical isolates. Over time, MRSA is becoming more common in various subsets of the general population. Some studies claim that many MRSA-colonized outpatients and their close contacts have had no health care contacts, but these studies have usually not considered contacts in outpatient clinics. Several other recent studies have found that all or a vast majority of patients with MRSA have had frequent contact with health care providers. Failure to wash hands and disinfect equipment between patients, which has been commonly seen in studies of health care worker compliance with infection control measures, may explain much of the continuing spread. The source of spread of antibiotic-resistant microbes can be likened to an iceberg, with clinically obvious infections representing the tip of the iceberg and most of the spread coming from clinically inapparent colonized patients who represent most of the reservoir for transmission. Surveillance cultures to identify this reservoir are important to the control of spread with effective barrier precautions. Such precautions have been shown to reduce the spread of MRSA 15.6-fold compared with standard precautions.

Journal Article↗
PubMed2000

Prevention of diseases caused by Staphylococcus aureus using the peptide RIP.

Staphylococcus aureus causes many diseases including cellulitis, keratitis, osteomyelitis, septic arthritis and mastitis. The heptapeptide RIP has been shown to prevent cellulitis in mice, which was induced by S. aureus strain Smith diffuse. Here we show that RIP can also significantly reduce the overall pathology and delay the onset of disease symptoms in several other models of S. aureus infections, including: keratitis (tested in rabbits against S. aureus 8325-4), osteomyelitis (tested in rabbits against S. aureus MS), mastitis (tested in cows against S. aureus Newbould 305, AE-1, and environmental infections) and septic arthritis (tested in mice against S. aureus LS-1). These findings substantiate that RIP is not strain specific in its inhibitory activity and that RIP is an effective inhibitor of bacterial pathology at multiple body sites following diverse routes and doses of administration. These findings strongly evidence the potential value of RIP as a chemotherapeutic agent.

Animals↗
PubMed2004

Residues 10-18 within the C5a receptor N terminus compose a binding domain for chemotaxis inhibitory protein of Staphylococcus aureus.

Chemotaxis inhibitory protein of Staphylococcus aureus (CHIPS) is excreted by the majority of S. aureus strains and is a potent inhibitor of C5a- and formylated peptide-mediated chemotaxis of neutrophils and monocytes. Recently, we reported that CHIPS binds to the C5a receptor (C5aR) and the formylated peptide receptor, thereby blocking activation by C5a and formylated peptides, respectively. The anaphylatoxin C5a plays an important role in host immunity and pathological inflammatory processes. For C5a a two-site binding model is proposed in which C5a initially binds the C5aR N terminus, followed by interaction of the C5a C-terminal tail with an effector domain on the receptor. We have shown here that CHIPS does not affect activation of the C5aR by a peptide mimic of the C5a C terminus. Moreover, CHIPS was found to bind human embryonic kidney 293 cells expressing only the C5aR N terminus. Deletion and mutation experiments within this C5aR N-terminal expression system revealed that the binding site of CHIPS is contained in a short stretch of 9 amino acids (amino acids 10-18), of which the aspartic acid residues at positions 10, 15, and 18 plus the glycine at position 12 are crucial. Binding studies with C5aR/C3aR and C5aR/IL8RA chimeras confirmed that CHIPS binds only to the C5aR N terminus without involvement of its extracellular loops. CHIPS may provide new strategies to block the C5aR, which may lead to the development of new C5aR antagonists.

Amino Acid Sequence↗
PubMed1971

Induction of hemolysin synthesis by tranformation in Staphylococcus aureus.

A nonhemolytic strain of Staphylococcus aureus was transformed with deoxyribonucleic acid extracted from two hemolytic strains of S. aureus. In each case the hemolysin pattern after transformation was identical to that of the donor strain. However, bacteriophage type, serotypes, and other biological properties of the recipient strain remained unaffected.

Bacteriological Techniques↗
PubMed1994

Staphylococcus aureus cellulitis: an unusual presentation.

Staphylococcus aureus has long been known as one of the most virulent microbes, with capabilities that make it threatening in both nosocomial and community-acquired infections. It remains the most frequent cause of skin-structure and traumatic infections in the community. S. aureus infections in the maxillofacial region are likely to be associated with a known portal of entry, but this is not always the case. Once invasion occurs, the organism may produce virulent enzymes including coagulase, hyaluronidase, proteases, DNA-ase, lipases, hemolysins, and lysozyme as well as exotoxins. Markel et al point out that cellulitis associated with coagulase-positive staphylococci will often resolve without abscess formation. Hence, there is often no site from which to obtain specimens, making this infection a diagnostic and therapeutic challenge. This report describes an infection in which the etiologic organism was identified as S. aureus. The source of the infection, however, remained unclear.

Cellulitis↗
PubMed1992

Percutaneous endoscopic gastrostomy as an unrecognized source of methicillin-resistant Staphylococcus aureus colonization.

Methicillin-resistant Staphylococcus aureus (MRSA) caused colonization or infection around the gastrostomy site of seven hospitalized patients, five of whom were in the long-term care unit. All cultures of gastrostomy sites were retrospectively reviewed, and 28% had MRSA. The gastrostomy site was responsible for 6.3% of all MRSA cultures, and 12.5% of all MRSA-positive patients with gastrostomy site cultures had involvement at that site. The implications of MRSA and gastrostomy tubes are discussed.

Aged↗
PubMed1981

Quantitative aspects of binding of canine serum immunoglobulins of Staphylococcus aureus protein A.

Quantitative interactions of Staphylococcus aureus protein A (SPA) and canine immunoglobulins (Ig) are described. The S aureus Cowan strain I bound canine IgG, IgM, and IgA, whereas binding was not observed with the SPA-negative Wood 46 strain of S aureus. In a quantitative adsorption experiment, the results indicated that IgA, though present in the lowest amounts in the samples, appeared to be substantially bound by SPA. Adsorption of sera with SPA-negative Wood strain bacteria resulted in nonspecific protein losses in supernatants of 0% to 15%.

Adsorption↗
PubMed1995

Staphylococcus aureus infections in diabetic patients.

Staphylococcus aureus infections may occur with greater frequency among patients with diabetes mellitus. This article reviews the available literature as it pertains to diabetes and S. aureus in three categories: colonization/carriage, bacteremia with or without metastatic complications, and dialysis-related infections. The clinical entity of pyomyositis is also discussed.

Bacteremia↗
PubMed1994

[Application of molecular epidemiology techniques in the study of food poisoning caused by Staphylococcus aureus].

BACKGROUND: The use of molecular epidemiology techniques has provided better knowledge as to the clonal organization of bacterian populations and thus allows better follow up of epidemics. An alimentary toxiinfection in a Barcelona school produced by Staphylococcus aureus was analyzed by the combination of epidemiologic, phenotype and genotype markers with the aim of determining the source of the alimentary contamination. METHODS: Nine strains of Staphylococcus aureus isolated in 6 food manipulators and 3 patients were studied with the following markers: biotype, antibiotype, phagotype, plasmid profile, polymorphism of the size of the restriction fragments of total DNA and ribotype. RESULTS: Epidemiologic study of the strains analyzed showed that both the phenotype markers and the plasmid profile are thecniques of little discriminatory value. The only clearly discriminatory technique used was ribotyping which defined 3 clones in the 9 strains of Staphylococcus aureus studied. CONCLUSIONS: Molecular study of isolated strains of Staphylococcus aureus was able to identify the causal origin of the alimentary toxiinfection in one of the 6 food manipulators studied.

Bacterial Typing Techniques↗
PubMed1996

The lipase from Staphylococcus aureus. Expression in Escherichia coli, large-scale purification and comparison of substrate specificity to Staphylococcus hyicus lipase.

The genes coding for the mature part of the lipases from Staphylococcus aureus NCTC8530 and Staphylococcus hyicus have been cloned and overexpressed in Escherichia coli as fusion proteins with an N-terminal hexa-histidine tag. The enzymes accumulated in the cytoplasm and were purified using sequential precipitation with protamine sulphate and ammonium sulphate, followed by metal-affinity and hydroxyapatite chromatography. The yield of pure lipase was 4.5 mg/g wet cells for S. aureus lipase and 13 mg/g for S. hyicus lipase. The purified enzymes need calcium for activity, albeit with different affinities, and a low residual activity was found in the absence of calcium. In contrast to S. hyicus lipase, not only strontium but also barium can replace calcium with full retention of activity of S. aureus lipase. Whereas S. hyicus lipase is optimally active at pH 8.5, the optimum pH for enzymatic activity for S. aureus lipase was found to be pH 6.5. The S. aureus lipase has a narrow substrate specificity: short-chain triacylglycerols and acyl esters of both p-nitrophenol and umbelliferone are readily degraded, whereas medium- and long-chain lipids, as well as phospholipids, are poor substrates. In contrast, S. hyicus lipase prefers phospholipids as substrate and hydrolyses neutral lipids irrespective of their chain length. The results are discussed in view of the large sequence similarity between both lipases.

Esters↗
PubMed2001

Recruitment of the mecA gene homologue of Staphylococcus sciuri into a resistance determinant and expression of the resistant phenotype in Staphylococcus aureus.

Strains of methicillin-resistant Staphylococcus aureus (MRSA) have become the most important causative agents of hospital-acquired diseases worldwide. The genetic determinant of resistance, mecA, is not a gene native to S. aureus but was acquired from an extraspecies source by an unknown mechanism. We recently identified a close homologue of this gene in isolates of Staphylococcus sciuri, a taxonomically primitive staphylococcal species recovered most frequently from rodents and primitive mammals. In spite of the close sequence similarity between the mecA homologue of S. sciuri and the antibiotic resistance determinant mecA of S. aureus, S. sciuri strains were found to be uniformly susceptible to beta-lactam antibiotics. In an attempt to activate the apparently "silent" mecA gene of S. sciuri, a methicillin-resistant derivative, K1M200 (for which the MIC of methicillin is 200 microg/ml), was obtained through stepwise exposure of the parental strain S. sciuri K1 (methicillin MIC of 4 microg/ml) to increasing concentrations of methicillin. DNA sequencing of the mecA homologue from K1M200 revealed the introduction of a point mutation into the -10 consensus of the promoter: the replacement of a thymine residue at nucleotide 1577 in the susceptible strain K1 by adenine in the resistant strain K1M200, which was accompanied by a drastic increase in transcription rate and the appearance of a new protein that reacted with monoclonal antibody prepared against the penicillin-binding protein 2A (PBP2A), i.e., the gene product of S. aureus mecA. Transduction of mecA from K1M200 (cloned into a plasmid vector) into a methicillin-susceptible S. aureus mutant resulted in a significant increase of methicillin resistance (from a methicillin MIC of 4 micro/ml to 12 and up to 50 microg/ml), the appearance of a low-affinity PBP detectable by the fluorographic assay, and the production of a protein that reacted in a Western blot with monoclonal antibody to PBP2A. Antibiotic resistance and the protein products disappeared upon removal of the plasmid-borne mecA homologue. The observations support the proposition that the mecA homologue ubiquitous in the antibiotic-susceptible animal species S. sciuri may be an evolutionary precursor of the methicillin resistance gene mecA of the pathogenic strains of MRSA.

Anti-Bacterial Agents↗
PubMed2001

[Evaluation of the efficacy of a program to control nosocomial spread of methicillin-resistant Staphylococcus aureus].

OBJECTIVE: To evaluate the efficacy of a program to control nosocomial spread of methicillin-resistant Staphylococcus aureus (MRSA). METHODS: Analysis of the incidence of infection and contamination due to MRSA in patients admitted to the hospital of Cremona 6 months before and 3 years after the introduction of the guidelines (July 1997). RESULTS: During the 42 months of the study period, on 80705 admissions, 511 cases of MRSA contamination/infection were identified, the incidence being 0.57 cases per 100 admissions. The infection rate dropped from 0.34 (IC95%: 0.25-0.45) in the first 6 months of the study, before the introduction of guidelines, to 0.17 (IC95%: 0.14-0.20) in the following 3 years (p=0.01). Severe infection decreased from 0.18 to 0.1 per 100 admissions, with a 44% decrease (p=0.058), while mild infections diminished from 0.16 to 0.07 per 100 admissions (p=0.045). Methicillin resistance among nosocomial isolates of Staphylococcus aureus was reduced from 53 % to 35 % (p<0.0001). CONCLUSIONS: The introduction of a program to control the nosocomial spread of MRSA proved effective in reducing both the incidence of infection and the methicillin-resistance of Staphylococcus aureus isolates. The cost effectiveness of the program seems very favourable.

Body Fluids↗
PubMed2006

Effects of combined 405-nm and 880-nm light on Staphylococcus aureus and Pseudomonas aeruginosa in vitro.

OBJECTIVE: The aim of this study was to determine the effect of a combination of 405-nm blue light and 880-nm infrared light on Staphylococcus aureus and Pseudomonas aeruginosa in vitro. BACKGROUND DATA: Reports indicate that certain wavelengths and treatment parameters of light promote the growth of bacteria, but our earlier study indicates that light at specific wavelengths and intensities are bactericidal for specific organisms (1). METHODS: Two common aerobes, Staphylococcus aureus and Pseudomonas aeruginosa were tested because of their frequent isolation from skin infections and wounds. Each organism was treated simultaneously with a combination of 405-nm and 880-nm light emitted by a cluster of Super Luminous Diodes (SLDs). Doses of 1, 3, 5, 10, and 20 Jcm2 were used. Colony counts were performed and compared to untreated controls using Student t tests and one-way ANOVA with Tukey and Scheffe post hoc analyses. RESULTS: The results revealed significant dose-dependent bactericidal effects of the combined blue and infrared light on Staphylococcus aureus (F 4,94 = 5.38, p = 0.001) and Pseudomonas aeruginosa (F 4,95 = 21.35, p < 0.001). With P. aeruginosa, the treatment reduced the number of bacteria colonies at all doses, achieving statistical significance at 1, 3, and 20 J cm2 doses and reducing bacterial colony by as much as 93.8%; the most effective dose being 20 J cm2. Irradiation of S. aureus resulted in statistically significant decreases in bacterial colonies at all dose levels; the most decrease, 72%, was also achieved with 20 Jcm2. CONCLUSION: Appropriate doses of combined 405-nm and 880-nm phototherapy can kill Staphylococcus aureus and Pseudomonas aeruginosa in vitro, suggesting that a similar effect may be produced in clinical cases of bacterial infection.

Colony Count, Microbial↗
PubMed1985

Evaluation of protein A and a commercial bacterin as vaccines against Staphylococcus aureus mastitis by experimental challenge.

Protein A and a commercial staphylococcal bacterin were evaluated by experimental challenge with Staphylococcus aureus (ATCC 29740). Thirty cows in first lactation were in three treatment groups, protein A, bacterin, and nonvaccinated controls. Studies were through three lactations and included bacteriological and cytological analyses of quarter milk samples. Rate of intramammary infection with Staphylococcus aureus was similar for vaccinated and unvaccinated cows. Rates of spontaneous cure within each lactation were significantly higher for vaccinated cows. For all three lactations, spontaneous cure rates were 83, 73, and 47% for protein A, bacterin, and control cows. Somatic cell counts were significantly lower for vaccinated cows for quarters infected with Staphylococcus aureus, but no differences were demonstrated for milk production by lactation. Incidence of clinical mastitis was higher in unvaccinated cows, but too few developed for a valid comparison.

Animals↗
PubMed1991

Cloning of the gene conferring resistance to mupirocin in Staphylococcus aureus.

A plasmid known to be associated with mupirocin resistance of Staphylococcus aureus has been isolated and a restriction enzyme map constructed. An EcoRI fragment of 4.05 kb from this plasmid has been cloned into an Escherichia coli-Staphylococcus aureus shuttle vector and shown to carry the gene for resistance to mupirocin. The DNA sequence of a small section of the gene has been determined and the derived amino acid sequence compared with a data bank. The amino acid sequence is identical for eight amino acids with the sequence of isoleucyl tRNA synthetase of E. coli. This finding adds to the evidence that mupirocin resistance is the result of a modified isoleucyl tRNA synthetase.

Amino Acid Sequence↗
PubMedDate not supplied

[Comparison of rapid latex and conventional methods for the identification of Staphylococcus aureus].

Rapid latex agglutination assay, staphaurex (Wellcome Diagnostics) was compared with the tube coagulase, thermo-stable nuclease, deoxyribonuclease and mannitol fermentation test for the identification of Staphylococcus aureus. A total of 277 clinical isolates of Staphylococcus aureus, 201 Staphylococcus epidermidis, and 25 Staphylococcus saprophyticus were tested. The results showed that sensitivities were: staphaurex, 99.6%; rabbit plasma, 99.6%; human plasma, 99.2%; thermostable nuclease, 100%; deoxyribonuclease, 100%; mannitol fermentation, 98.9%; as for specificities results showed: staphaurex, 96.6%; rabbit plasma 100%; human plasma, 100%; thermo-stable nuclease, 98.7%; deoxyribonuclease 95.7%; mannitol fermentation, 91.1%; respectively. In our study, staphaurex is recommended because it is simple to operate, save in time and economic in cost.

Animals↗