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PubMed2004

The teicoplanin-associated locus regulator (TcaR) and the intercellular adhesin locus regulator (IcaR) are transcriptional inhibitors of the ica locus in Staphylococcus aureus.

Infections involving Staphylococcus aureus are often more severe and difficult to treat when the organism assumes a biofilm mode of growth. The polysaccharide poly-N-acetylglucosamine (PNAG), also known as polysaccharide intercellular adhesin, is synthesized by the products of the intercellular adhesin (ica) locus and plays a key role in biofilm formation. Numerous conditions and exogenous factors influence ica transcription and PNAG synthesis, but the regulatory factors and pathways through which these environmental stimuli act have been only partially characterized. We developed a DNA affinity chromatography system to purify potential regulatory proteins that bind to the ica promoter region. Using this technique, we isolated four proteins, including the staphylococcal gene regulator SarA, a MarR family transcriptional regulator of the teicoplanin-associated locus TcaR, DNA-binding protein II, and topoisomerase IV, that bound to the ica promoter. Site-directed deletion mutagenesis of tcaR indicated that TcaR was a negative regulator of ica transcription, but deletion of tcaR alone did not induce any changes in PNAG production or in adherence to polystyrene. We also investigated the role of IcaR, encoded within the ica locus but divergently transcribed from the biosynthetic genes. As has been shown previously in Staphylococcus epidermidis, we found that IcaR was also a negative regulator of ica transcription in S. aureus. We also demonstrate that mutation of icaR augmented PNAG production and adherence to polystyrene. Transcription of the ica locus, PNAG production, and adherence to polystyrene were further increased in a tcaR icaR double mutant. In summary, TcaR appeared to be a weak negative regulator of transcription of the ica locus, whereas IcaR was a strong negative regulator, and in their absence PNAG production and biofilm formation were enhanced.

Acetylglucosamine↗
PubMed2006

Discrimination of Staphylococcus aureus strains from different species of Staphylococcus using Fourier transform infrared (FTIR) spectroscopy.

Staphylococcus aureus is a widespread opportunistic pathogen that can cause food-borne illness and is sometimes associated with raw milk and raw milk cheese products. The traditional taxonomic procedures for classification of staphylococcal species are time consuming and often several tests are required. FTIR spectroscopy offers a rapid method for the discrimination and identification of S. aureus strains isolated from raw milk and raw milk cheeses. FTIR spectroscopy was used to discriminate S. aureus from other species of Staphylococcus. This was achieved by using a model composed of 39 species and subspecies of Staphylococcus. The model was validated using a set of spectra of strains isolated from raw milk and different varieties of French raw milk cheese. S. aureus was successfully discriminated from the other species of Staphylococcus and all the strains of S. aureus isolated from raw milk and different varieties of French raw milk cheese were also successfully identified as such. These results demonstrated that FTIR spectroscopy is a rapid (results obtained within 24 h starting from a pure strain or a single colony) and robust method for the identification of S. aureus isolates of dairy origin and food-borne origin in general.

Animals↗
PubMedDate not supplied

[Treatment and prevention of Staphylococcus aureus].

The number of Staphylococcus aureus (S. aureus) community and nosocomial acquired infections have increased in the last twenty years. Between 1990 and 1992, this pathogen has become the most frequent source of nosocomial infections 1,2. On the other hand, as result of antibiotherapy selection pressure, we observe a dramatic increase in the methicillin-resistant S. aureus (MRSA) infections 3,4. With the recent emergence of multiresistant strains, including glycopeptides resistance, the treatment of these infections became still more difficult 2,4-6. It's important to prevent resistant strains emergence. To prevent further emergence of resistant strains, the use of antibiotherapy must be optimised, laboratory methods for the detection of resistant pathogens must be enhanced and strict precautions should be taken following of the infection or colonization of patients 6-10. In this paper, we review anti-staphylococci history evolution and point out the present recommendations for the treatment and prevention of Staphylococcus aureus infections and colonization.

Community-Acquired Infections↗
PubMed1999

Analysis of vancomycin population susceptibility profiles, killing activity, and postantibiotic effect against vancomycin-intermediate Staphylococcus aureus.

Methicillin-resistant Staphylococcus aureus strains with decreased vancomycin susceptibility have been isolated from patients in the United States and Japan. The impact of decreased vancomycin susceptibility on the drug's pharmacodynamic parameters has not been addressed. We studied the activity of vancomycin against three clinical strains of vancomycin intermediate-susceptible Staphylococcus aureus (VISA) under high- and low-inoculum conditions, with stationary- and logarithmic-growth-phase kill curves, and in postantibiotic effect (PAE) experiments. We also investigated the stability of the decreased vancomycin susceptibility by using population susceptibility profiles. The respective vancomycin microdilution MICs and MBCs for VISA strains HIP5836, 14379, and Mu50 were 8 and 8, 8 and 8, and 8 and 16 microg/ml. HIP5836 had the most homogeneous elevation of vancomycin MICs, because the MIC for nearly all bacteria in the inoculum was 8 microg/ml. The population MICs (defined as the lowest vancomycin concentration inhibiting 99. 9% of growth) for the first serial passages of HIP5836, Mu50, and 14379 were 8, 4, and 2 microg/ml, respectively. After 10 passages, they decreased to 4, 2, and 1 microg/ml, respectively. The Mu50 population MIC increased to 12 microg/ml after five serial passages on vancomycin agar. In the low- and high-inoculum kill curves, time to 99.9% killing was significantly (P < 0.05) longer for both Mu50 and HIP5836 than that for 14379 and a control strain. However, colony counts at 24 h were similar to those of the vancomycin-sensitive strain for all VISA strains. The PAE (at 4x MIC) ranged from 1.3 h for 14379 to 2.0 h for HIP5836 and was similar to or greater than the PAE against the vancomycin-sensitive strain. In conclusion, we found that the decreased vancomycin susceptibility increased during persistent exposures to the drug and decreased upon removal of the selective pressure. The decreased vancomycin susceptibility decreased the rate of vancomycin killing, but did not affect the extent of killing or the PAE.

Anti-Bacterial Agents↗
PubMed2003

Assessment of the opsonic activity of purified bovine sIgA following intramammary immunization of cows with Staphylococcus aureus.

The phagocytosis of Staphylococcus aureus by bovine polymorphonuclear neutrophils (PMN) requires the presence of antibodies. Among the major isotypes of bovine antibodies, IgG2 and IgM are considered opsonic for bovine PMN. However, the role of purified bovine secretory IgA (sIgA) as an opsonin has not been assessed. In the present study, IgG2 were obtained from serum and sIgA, IgG1, and IgM were purified from the colostrums of three cows intramammarily immunized with heat-killed Staphylococcus aureus. The Ig preparations were assayed for specific antibodies, and the opsonic capacity of every isotype was investigated. Despite the presence of antibodies, we observed no distinct chemiluminescence response of PMN stimulated with sIgA- or IgG1-opsonized S. aureus, whereas IgM or IgG2 bound to bacteria induced a marked chemiluminescence response. Moreover, the counting of internalized bacteria per PMN after phagocytosis revealed a low uptake of S. aureus opsonized with sIgA or IgG1, in contrast to IgM or IgG2, which triggered efficient ingestion of bacteria. Priming of neutrophils by TNF-alpha, IFN-gamma, or C5adesArg did not promote an oxidative burst or uptake of sIgA-opsonized S. aureus to a greater extent than with IgG1-opsonized bacteria. Furthermore, analysis of uningested bacteria by flow cytometry after incubation with PMN showed a preferential uptake of IgM-opsonized S. aureus by PMN and only few sIgA-positive stained bacteria were PMN-associated. These experiments indicate that sIgA, like IgG1 and unlike IgM or IgG2, could not be considered as a major opsonin for phagocytosis of S. aureus by bovine blood PMN.

Animals↗
PubMed1997

Molecular cloning and sequence analysis of the dnaA gene of Staphylococcus aureus.

The dnaA gene of Staphylococcus aureus has now been cloned and sequenced. The deduced amino acid sequence of Staphylococcus aureus DnaA protein is 62% and 39% identical to those of the DnaA protein from Bacillus subtilis and Escherichia coli, respectively. Expression of the dnaA gene of Staphylococcus aureus in Escherichia coli caused lethality in an oriC-dependent manner.

Amino Acid Sequence↗
PubMed1989

Comparison of test systems for recognition of methicillin resistance in Staphylococcus aureus.

Methicillin resistance in Staphylococcus aureus can be difficult to recognize because it may be expressed in only a small portion of the population. The optimal reference to use in comparing different test systems is controversial. In this study MIC values of less than or equal to 4 mg/l as observed in two experiments, each including 12 test systems (24 h incubation), were used to define strains as methicillin-susceptible. This strict standard was used to compare 24 quantitative and 36 agar diffusion test systems applied to 61 strains. These test systems included six agar media (Mueller Hinton, Oxoid and BBL; and Iso-Sensitest, Oxoid; all with and without 5% NaCl), three broth media of the same type, two incubation temperatures (30 degrees C and 37 degrees C), two incubation times (24 h and 48 h) and five disc types [methicillin 10 micrograms (M 10), three types of methicillin 5 micrograms (M 5) and oxacillin 1 microgram (O 1)]. Standardized high inocula were used. It was concluded that 24 h incubation is preferable to 48 h; at 24 h, differences in recognition of methicillin-resistant Staphylococcus aureus (MRSA) among 12 quantitative test systems were not statistically significant; incubation at 30 degrees C gave slightly better results in diffusion tests. Reproducibility of quantitative data (Friedman test) was better on Mueller Hinton media (p less than 0.001) than on Iso-Sensitest medium in both dilution and agar diffusion test systems. The rank order of discs was M 5 greater than M 10 greater than O 1 (p less than 0.001). An inhibition zone of less than 13 mm with a M 5 micrograms (BBL) disc should be interpreted as MRSA.

Culture Media↗
PubMedDate not supplied

Vancomycin intermediate-resistant Staphylococcus aureus (VISA).

Methicillin-resistant Staphylococcus aureus (MRSA) has been an infectious disease problem since the early 1980s and until recently was uniformly susceptible to vancomycin, the drug known as the "last resort." Recent reports indicate that Staphylococcus aureus has continued to mutate and has developed intermediate resistance to vancomycin (VISA). This article lists some of the potential clinical manifestations of Staphylococcus aureus as well as a possible explanation of the phenomenon of antibiotic resistance. The reported cases of VISA are reviewed, and intervention strategies for prevention and control are discussed.

DNA, Bacterial↗
PubMedDate not supplied

Petrifilm rapid S. aureus Count Plate method for rapid enumeration of Staphylococcus aureus in selected foods: collaborative study.

A rehydratable dry-film plating method for Staphylococcus aureus in foods, the 3M Petrifilm Rapid S. aureus Count Plate method, was compared with AOAC Official Method 975.55 (Staphylococcus aureus in Foods). Nine foods-instant nonfat dried milk, dry seasoned vegetable coating, frozen hash browns, frozen cooked chicken patty, frozen ground raw pork, shredded cheddar cheese, fresh green beans, pasta filled with beef and cheese, and egg custard-were analyzed for S. aureus by 13 collaborating laboratories. For each food tested, the collaborators received 8 blind test samples consisting of a control sample and 3 levels of inoculated test sample, each in duplicate. The mean log counts for the methods were comparable for pasta filled with beef and cheese; frozen hash browns; cooked chicken patty; egg custard; frozen ground raw pork; and instant nonfat dried milk. The repeatability and reproducibility variances of the Petrifilm Rapid S. aureus Count Plate method were similar to those of the standard method.

Colony Count, Microbial↗
PubMed1995

Frequency of toxic shock syndrome toxin- and enterotoxin-producing clinical isolates of Staphylococcus aureus.

In 183 clinical isolates of Staphylococcus aureus, toxic shock syndrome toxin was detected in 13.7%, enterotoxin A in 20.2%, enterotoxin B in 7.7%, enterotoxin C in 5.5% and enterotoxin D in 3.3%. Seventy-three (39.9%) of the strains were found to produce one or more toxins. Multiple secretion of toxins was rare (< 1% of all strains) except for the combinations enterotoxin A with toxic shock syndrome toxin and enterotoxin A with enterotoxin D. These combinations were observed at significantly higher frequencies (4.9% and 2.2%, respectively) than would have been expected from values calculated from respective individual frequencies (0.88% and 0.06%) (p < 0.0001). In comparison with Staphylococcus aureus strains isolated from miscellaneous material, Staphylococcus aureus blood culture isolates produced enterotoxin D in significantly larger amounts and at higher frequencies (p = 0.01 in both cases). These toxins might play an important pathogenic role in Staphylococcus aureus infections.

Bacterial Toxins↗
PubMed2005

Trends and outcome of nosocomial and community-acquired bloodstream infections due to Staphylococcus aureus in Finland, 1995-2001.

In Finland, Staphylococcus aureus bloodstream infections are caused predominantly (>99%) by methicillin-sensitive strains. In this study, laboratory-based surveillance data on Staphylococcus aureus bloodstream infections occurring in Finland from 1995 to 2001 were analyzed. Preceding hospitalizations for all persons with Staphylococcus aureus bloodstream infections were obtained from the national hospital discharge registry, and data on outcome was obtained from the national population registry. An infection was defined as nosocomial when a positive blood culture was obtained more than 2 days after hospital admission or within 2 days of admission if there was a preceding hospital discharge within 7 days. A total of 5,045 cases were identified. The annual incidence of Staphylococcus aureus bloodstream infection rose by 55%, from 11 per 100,000 population in 1995 to 17 in 2001. The increase was detected in all adult age groups, though it was most distinct in patients >74 years of age. Nosocomial infections accounted for 51% of cases, a proportion that remained unchanged. The 28-day death-to-case ratio ranged from 1% in the age group 1-14 years to 33% in patients >74 years of age. The 28-day death-to-case ratios for nosocomial and community-acquired infections were 22% and 13%, respectively, and did not change over time. The increase in incidence among elderly persons resulted in an increase in the annual rate of mortality associated with Staphylococcus aureus bloodstream infections, from 2.6 to 4.2 deaths per 100,000 population per year. Staphylococcus aureus bloodstream infections are increasing in Finland, a country with a very low prevalence of methicillin resistance. While the increase may be due in part to increased reporting, it also reflects a growing population at risk, affected by such factors as high age and/or severe comorbidity.

Adolescent↗
PubMed1963

ABSCESS-FORMING FACTOR(S) PRODUCED BY STAPHYLOCOCCUS AUREUS. II. ABSCESS FORMATION AND IMMUNITY BY A STAPHYLOCOCCUS AND ITS MUTANTS.

Lam, Gow T. (Jefferson Medical College, Philadelphia, Pa.), Francis J. Sweeney, Jr., Charlotte M. Witmer, and Robert I. Wise. Abscess-forming factor(s) produced by Staphylococcus aureus. II. Abscess formation and immunity by a Staphylococcus and its mutants. J. Bacteriol. 86:87-91. 1963.-Three mutants were derived from a virulent parent strain of Staphylococcus aureus by ultraviolet irradiation. One mutant retained coagulase but lost its hemolytic activity; a second had no coagulase but retained its hemolysin; and a third contained hemolysin and bound coagulase but no free coagulase. The parent strain was coagulase-positive, hemolysin-positive, and possessed all the known extracellular products. All four strains were compared by bacteriophage typing, mannitol utilization, and antibiotic sensitivity tests. The four isolates were studied for their pathogenicity in Swiss albino mice and four strains of inbred mice. Their immunological characteristics as studied by repeated subcutaneous injections are reported. The importance of hemolysin and the coagulase in abscess formation is discussed. Local immunity was produced only by the parent strain, but abscesses were produced by all the strains containing coagulase.

Abscess↗
PubMed1996

Genomic variability of Staphylococcus aureus and the other coagulase-positive Staphylococcus species estimated by macrorestriction analysis using pulsed-field gel electrophoresis.

The genomic DNAs of 95 culture collection and hospital Staphylococcus aureus subsp. aureus strains of various origins, as well as the genomic DNAs of other coagulase-positive Staphylococcus species, were cleaved with restriction endonuclease SmaI and subjected to pulsed-field gel electrophoresis. The levels of similarity of the SmaI restriction patterns of the S. aureus subsp. aureus strains varied from 30 to 100%, which is considered characteristic of this species; thus, these organisms belonged to the same species restriction group. Within this range of similarity values 13 S. aureus intraspecies restriction groups were identified, and each group consisted of strains whose levels of similarity ranged from 65 to 100%. S. aureus subsp. aureus CCM 885T (T = type strain) belonged to the major intraspecies restriction group that comprised 39% of the S. aureus strains which we studied. The strains of the other coagulase-positive staphylococci, including Staphylococcus aureus subsp. anaerobius, Staphylococcus hyicus, Staphylococcus intermedius, Staphylococcus delphini, and Staphylococcus schleiferi subsp. coagulans, clustered with their type strains in separate restriction groups. S. aureus subsp. aureus exhibited almost no similarity to these species. We found 44-kb SmaI fragments in all of the S. aureus subsp. aureus and S. aureus subsp. anaerobius strains studied, and these fragments are considered characteristic of the species S. aureus. The high level of homology of these fragments was confirmed by the results of DNA hybridization experiments in which we used representatives of individual intraspecies restriction groups. Of the other staphylococci studied, only Staphylococcus epidermidis and one strain of S. hyicus contained these fragments. However, the levels of homology between these fragments and the fragments of S. aureus were found to be very low.

Coagulase↗
PubMed1982

Studies on multi-antibiotic resistant strains of Staphylococcus aureus.

Twenty-seven isolates of Staphylococcus aureus were found to be resistant to methicillin, nafcillin, tobramycin, gentamicin, amikacin, cefoxitin, clindamycin, erythromycin and chloramphenicol by disc diffusion testing and tube dilution studies; they were sensitive to cefamandole, cephalothin and vancomycin by disc testing. A discrepancy between minimum inhibitory and bactericidal concentrations was noted for the cephalosporins which was not appreciated on disc testing. All isolates were very sensitive to rifampin (minimum bactericidal concentration 0.3 mg/l). All isolates were susceptible to phage type 83A. A subpopulation of variant small-colony forms of Staphylococcus aureus was recovered when superinhibitory amounts of aminoglycosides and methicillin were used. The variant Staphylococcus aureus strains retained the same antibiotic susceptibility patterns and phage type as their parent strain of Staphylococcus aureus. Further studies are in progress concerning these isolates and their impact on the hospital flora at our institution.

Anti-Bacterial Agents↗
PubMed1969

Effect of sublethal heat on the metabolic activity of Staphylococcus aureus.

Cells of Staphylococcus aureus MF-31 which have been heat-injured at 52 C have an altered metabolic activity. Analyses of whole-cell preparations by means of the Thunberg technique and Warburg manometry showed decreased dehydrogenase activity and oxygen uptake on a variety of substrates. In cell-free extracts prepared from injured cells, it was demonstrated that the specific activity of fructose diphosphate aldolase, lactate dehydrogenase, and butanediol dehydrogenase was less than that of extracts prepared from normal unheated cells. Recovery of the heat-injured cells in a suitable medium supported a return of the dehydrogenase activity and oxygen uptake, but the activity of the enzymes in cell-free extracts prepared from such partially recovered cells did not fully return to the level of normal (unheated) preparations. Addition of chloramphenicol or actinomycin D to the recovery medium, singly or in combination, retarded the return of the normal metabolic activity. Radiorespirometric experiments indicated that the percentage participation of the Embden-Meyerhoff Parnas and hexose monophosphate pathways remained the same for normal and heat-injured cells. The sublethal heat treatment decreased the catabolic capabilities of S. aureus and the production of selected end products associated with the metabolism of glucose.

Alcohol Oxidoreductases↗
PubMed1974

Genetic evidence for the physiological significance of the D-tagatose 6-phosphate pathway of lactose and D-galactose degradation in staphylococcus aureus.

Mutants of Staphylococcus aureus were isolated which were unable to utilize d-galactose or lactose, but which were able to utilize all other carbohydrates tested. Growth of the mutants on a peptone-containing medium was inhibited by d-galactose. Of those mutants selected for further study, one (tagI2) was missing d-galactose 6-phosphate isomerase, one (tagK3) was missing d-tagatose 6-phosphate kinase, and one (tagA4) was missing d-tagatose 1, 6-diphosphate aldolase. Each of these mutants accumulated the substrate of the missing enzyme intracellularly. Spontaneous revertants of each of the mutants simultaneously regained their ability to utilize d-galactose and lactose, lost their sensitivity to d-galactose, regained the missing enzymatic activities, and no longer accumulated intermediates of the d-tagatose 6-phosphate pathway. These data support our previous contention that the physiologically significant route for the metabolism of d-galactose and the d-galactosyl moiety of lactose in S. aureus is the d-tagatose 6-phosphate pathway. Furthermore, a mutant constitutive for all three enzymes of this pathway was isolated, indicating that the products of the tagI, tagK, and tagA genes are under common genetic control. This conclusion was supported by the demonstration that d-galactose 6-phosphate isomerase, d-tagatose 6-phosphate kinase, and d-tagatose 1, 6-diphosphate aldolase are coordinately induced in the parental strain.

Aldehyde-Lyases↗
PubMed1967

Effect of high oxygen concentration on virulence of Staphylococcus aureus.

Cultures of Staphylococcus aureus were agitated and treated with oxygen or air for a period of 29 days. At intervals of 1, 3, 9, 15, and 29 days, samples of washed cells were tested for coagulase activity and for abscess-producing ability. It was found that aeration with agitation initially increased abscess formation and that the increase was of the same magnitude for oxygen and air. Continued treatment beyond 1 day resulted in a progressive decrease in this activity which was more pronounced in the oxygenated cultures. Throughout the treatment, the bound coagulase activity remained constant. Thus, there appeared to be no quantitative relationship of coagulase titer with virulence as expressed by lesion formation.

Bacteriological Techniques↗