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PubMed1972

Reliability of the Kirby-Bauer disc diffusion method for detecting methicillin-resistant strains of Staphylococcus aureus.

The resistance of Staphylococcus aureus to methicillin and related drugs can be reliably determined by using the Kirby-Bauer method of susceptibility testing if the incubation temperature is 35 C or below, but resistance may be missed at 37 C. The 1-mug discs of oxacillin and nafcillin or the 5-mug discs of methicillin may be used for this purpose but not the 1-mug discs of cloxacillin. The latter fail to discriminate between sensitive and resistant staphylococci by zone measurement; some resistant strains of staphylococci may show larger zones of inhibition than sensitive strains. Stability of these antibiotic-containing discs was studied under conditions of temperature and humidity variation that might be encountered in a clinical laboratory refrigerator. Oxacillin discs were the most stable and are to be preferred for susceptibility testing. Nafcillin discs were less stable, and methicillin discs lose their potency rapidly unless carefully stored in a refrigerator with a desiccant.

Cloxacillin↗
PubMed1998

Methicillin resistant Staphylococcus aureus as a cause of chorioamnionitis.

BACKGROUND: Chorioamnionitis is a leading cause of morbidity and mortality in preterm infants. Only rarely is Staphylococcus aureus implicated. A case of methicillin resistant Staphylococcus aureus causing chorioamnionitis and endometritis is presented. CASE REPORT: A 39-year-old gravida 2 para 1 female, who previously worked as the unit clerk in the pediatric pulmonary unit of a children's hospital, was initially admitted at 22 weeks with a shortened cervix. The patient refused emergency cerclage. She was released from the hospital and returned at 25 4/7 weeks' estimated gestational age with possible spontaneous rupture of membranes. An amniocentesis was performed and revealed a gram stain positive for many gram positive cocci as well as a glucose of < 2 mg%. The patient was started on intravenous ampicillin and gentamicin and induction of labor with oxytocin was begun. Approximately 1 day after the patient's delivery, the culture from the amniocentesis was noted to have grown methicillin resistant Staphylococcus aureus, and the patient's (as well as the neonate's) regimen was switched to vancomycin. CONCLUSION: A Medline search revealed no cases of methicillin resistant Staphylococcus aureus causing chorioamnionitis. When chorioamnionitis or refractory endometritis is encountered in a patient who works in the health care industry, methicillin resistant staphylococcus aureus must be considered.

Adult↗
PubMed1967

Protein synthesis in a cell-free extract from Staphylococcus aureus.

Cell-free Staphylococcus aureus extracts have been prepared which actively incorporate amino acids into protein. The requirements for amino acid incorporation of this preparation were strongly suggestive of de novo protein synthesis, since it showed an absolute requirement for ribosomes, 105,000 x g supernatant fluid, energy source, and magnesium ion. The stability of these extracts was greatly improved by use of dithiothreitol instead of mercaptoethanol as a sulfhydryl protecting reagent. Data were presented to show that the binding of aminoacyl-soluble ribonucleic acid to ribosomes did not require guanosine triphosphate and supernatant enzyme. The major characteristic which distinguishes this system from other cell-free systems is the much higher magnesium concentration required to maintain ribosomes intact and to obtain the maximal incorporation of amino acids. Addition of polyuridylic acid, polyadenylic acid, or polycytidylic acid caused about 60-fold, 30-fold, or 4-fold stimulation of the incorporation of phenylalanine, lysine, or proline, respectively. Studies by density gradient sedimentation indicated that radioactive polyuridylic acid or polyadenylic acid was associated with the monosomes. This complex can actively synthesize polypeptides. On the other hand, the nascent protein synthesized under the direction of endogenous messenger ribonucleic acid was associated with both polysomes and monosomes.

Amino Acids↗
PubMed1974

Nature of the genetic determinant controlling exfoliative toxin production in Staphylococcus aureus.

Phage group II Staphylococcus aureus has been identified as the etiological agent of the staphylococcal scaleded skin syndrome. The development of an animal model system permitted fulfillment of Koch's postulates and recognition of exfoliative toxin (ET) as being responsible for some of the clinical manifestations of this syndrome. Initial studies directed toward associating a lysogenic phage with the genetic control of ET synthesis failed to support this hypothesis. Growth of two Tox(+) strains at 44 C was more effective than growth in ethidium bromide or sodium dodecyl sulfate in eliminating the ability to produce ET. The early and rapid accumulation of ET-negative (Tox(-)) variants during growth of strain UT 0007 at 44 C, the lack of any selective advantage of the Tox(-) variants over Tox(+) cells during growth at 44 C, and an enhanced elimination frequency at 44 C of 97.9% over the spontaneous frequency of loss strongly suggest that the gene for ET synthesis is extrachromosomal. Additional evidence suggests that this gene is located on a plasmid which is not associated with genes for penicillinase synthesis and cadmium resistance. Two Tox(+) strains harbored lysogenic phage capable of transducing cadmium resistance, but not penicillin resistance, to specific Tox(-) recipients.

Animals↗
PubMed2006

Real-time quantitative PCR of Staphylococcus aureus and application in restaurant meals.

Staphylococcus aureus is considered the second most common pathogen to cause outbreaks of food poisoning, exceeded only by Campylobacter. Consumption of foods containing this microorganism is often identified as the cause of illness. In this study, a rapid, reliable, and sensitive real-time quantitative PCR was developed and compared with conventional culture methods. Real-time quantitative PCR was carried out by purifying DNA extracts of S. aureus with a Staphylococcus sample preparation kit and quantifying it in the LightCycler system with hybridization probes. The assay was linear from a range of 10 to 10(6) S. aureus cells (r2 > 0.997). The PCR reaction presented an efficiency of >85%. Accuracy of the PCR-based assay, expressed as percent bias, was around 13%, and the precision, expressed as a percentage of the coefficient of variation, was 7 to 10%. Intraday and interday variability were studied at 10(2) CFU/g and was 12 and 14%, respectively. The proposed method was applied to the analysis of 77 samples of restaurant meals in Valencia (Spain). In 11.6% of samples S. aureus was detected by real-time quantitative PCR, as well as by the conventional microbiological method. An excellent correspondence between real-time quantitative PCR and microbiological numbers (CFU/g) was observed with deviations of < 28%.

Colony Count, Microbial↗
PubMedDate not supplied

[Staphylococcus aureus sepsis in hospitalized non neutropenic patients: retrospective clinical and microbiological analysis].

Staphylococcus aureus is one of the leading agents of nosocomial infection among adult patients. The aim of this study was to determine the predisposing factors and secondary complications of Staphylococcus aureus septicemia (SAS) in non neutropenic patients, as well as the predictors of the outcome in non neutropenic patients with SAS. We performed a retrospective study of 56 cases of SAS that occurred from January 1997 through June 2001 in patients hospitalized in medical wards at the Policlinico Umberto I, "La Sapienza" University of Rome; we excluded surgical patients and those admitted to the intensive care unit. The median age was 61.9 years (range 24-89 years), 29 (51%) patients were male, and infection was hospital-acquired in 83.5% of cases. Metastatic infections were found in 12 patients (21.4%), with 6 (10.7%) developing infectious endocarditis; the relapse rate was 8.9%; 30.3% of Staphylococcus aureus isolates were methicillin-resistant. The overall mortality was 41% and the attributable mortality 28.5%. Twenty-nine patients who developed metastatic infections or died for sepsis were compared with 27 patients who did not develop complications. At univariate analysis, the following factors were associated with a complicated course: delay to adequate antibiotic therapy (2.46 vs 1.15 days, p < 0.03), persistent Staphylococcus aureus bacteremia during antibiotic therapy (3.56 vs 1.51 days, p = 0.01), septic shock (58.6 vs 3.7%, p < 0.002), bacteremic pneumonia as the source of bacteremia (17.2 vs 0%, p = 0.02), and the increased severity of illness at the onset of SAS as evaluated using an "illness score" (4.2 vs 2.1, p < 0.002). At multivariate analysis, septic shock (p < 0.01) and delay to adequate antibiotic therapy (p = 0.05) were confirmed as associated with a complicated outcome. SAS in non neutropenic patients is associated with significant morbidity consequent to a high rate of metastatic infectious disease and with a considerable related mortality.

Adult↗
PubMed1992

The role of capsular antigens in Staphylococcus aureus immunity.

Most clinical blood isolates of Staphylococcus aureus have been shown to be encapsulated. Techniques are now available for the preparation of type-specific capsular antisera and to provide reliable serologic methods for the identification of clinical isolates of Staphylococcus aureus. Epidemiologic studies in the U.S.A. and Europe indicated the prevalence of capsular types 5 and 8 among clinical isolates from human, bovine, and poultry. Encapsulated types 5 and 8 resisted in vitro phagocytosis and specific anti-capsular serum facilitated type-specific opsonization of S. aureus by polymorphonuclear leukocytes (PMN). The structure of the prevalent types 5 and 8 capsular polysaccharides (CP) have been elucidated. Vaccines of CP conjugated to exotoxin A of Pseudomonas aeruginosa have been prepared and have been injected into animals and human volunteers. Antibodies elicated by these conjugates facilitated opsonization of specific S. aureus types by human PMN.

Antigens, Bacterial↗
PubMed1984

Opsonic activity of fibronectin in the phagocytosis of Staphylococcus aureus by polymorphonuclear leukocytes.

The effect of the opsonic activity of human purified fibronectin on phagocytosis of Staphylococcus aureus by human polymorphonuclear leukocytes was investigated. After opsonization with fibronectin there was a significant increase in the rate of phagocytosis of four out of six Staphylococcus aureus strains. Both attachment to and ingestion by leukocytes was affected, as revealed by lysostaphin treatment. Incubation of leukocytes with fibronectin prior to phagocytosis did not enhance the phagocytosis of Staphylococcus aureus. This shows that the observed enhancement of phagocytosis was dependent on the binding of fibronectin to Staphylococcus aureus. The ability of fibronectin to opsonize different strains of Staphylococcus aureus varied with the strain. A variation was also observed in fibronectin-induced phagocytosis by leukocytes from different donors.

Blood Bactericidal Activity↗
PubMed1978

Activation of human B and T lymphocytes by protein A of Staphylococcus aureus.

Protein A from Staphylococcus aureus, in soluble form or coupled to Sepharose beads, acts as a polyclonal B cell activator (PBA) for human lymphocytes in blood and spleen. PBA activity was demonstrated in spleen cells by the ability of protein A to induce the formation of intracellular immunoglobulin synthesis and to activate polyclonal antibody secretion demonstrated against fluorescein isothiocyanate-coupled sheep erythrocytes in a modified hemolysis in gel assay. More plaqueforming cells (PFC) were seen in unseparated cells than in purified B cells. In blood lymphocytes, only few PFC were activated by soluble protein A. Protein A increased DNA synthesis in blood and spleen cells. At a concentration of 100 microgram/ml the peak response was on day 4 or 5, but at 1 microgram/ml the peak response occurred later. On day 4 of culture, high mitogenic activity was seen in unseparated lymphocytes or mixtures of separated B and T cells, whereas in enriched B and T cell suspensions activity was low. On day 7, however, DNA synthesis in both the enriched B and T cells was higher than in mixtures of B and T cells. Protein A stimulated DNA synthesis in thymus cells with a peak response on day 6. It is concluded that protein A alone or as an IgG complex can activate both B and T cells, though the mechanism of activation is not known and may be different for B and T cells.

B-Lymphocytes↗
PubMed1997

Brucellosis of the spine with a synchronous Staphylococcus aureus pyogenic elbow infection.

Staphylococcus aureus osteomyelitis and pyogenic arthritis has a different pattern in the elderly than in the young. The axial skeleton is the most frequent site of infection and treatment is usually by intravenous antibiotics. We report a case of Staph. aureus septic arthritis of the elbow with concomitant osteomyelitis of the spine that was thought to be due to Staph. aureus, but culture of debrided material from the lesion grew Brucella in culture. We suggest that in the elderly it is advisable to obtain a tissue culture diagnosis and not to instigate therapy based on positive blood cultures or a concomitant infection.

Aged↗
PubMed2005

Changes in blood and milk lymphocyte sub-populations during acute and chronic phases of Staphylococcus aureus induced bovine mastitis.

Staphylococcus aureus (S. aureus) often causes long-lasting chronic sub-clinical udder infections in dairy cows. To investigate if this can be due to a negative impact of S. aureus on lymphocytes important for the immune defence, alterations in proportions and expression intensity of CD4+, CD8+, WC1+, B and IL-2R+ lymphocytes was studied in blood and milk, as S. aureus mastitis developed from acute clinical to chronic sub-clinical form. Six healthy dairy cows were inoculated with S. aureus in one udder quarter per cow, and one quarter per cow acted as an uninfected control. Blood samples, and milk samples from infected and non-infected quarters were collected before infection and for five weeks after infection. All infected quarters developed acute clinical mastitis, of which five turned into chronic sub-clinical mastitis. In infected quarters, the proportions of all lymphocyte sub-sets, except WC1+ cells, differed in acute phase compared to pre-infection, while the dominant finding in the chronic phase was increased expression intensities per cell. An impact on blood lymphocytes and milk lymphocytes in non-infected quarters also occurred, mainly during the chronic phase. The most prominent finding was the increased proportion and expression of B-lymphocytes in blood, infected and non-infected quarters during chronic sub-clinical mastitis. As S. aureus can invade and survive intracellularly, a preferential stimulation of B-cells, suggesting development of a humoral response, may not be sufficient to eliminate intracellular bacteria, which could explain the persistence of the infection.

Acute Disease↗
PubMed1967

Liberation of surface-located penicillinase from Staphylococcus aureus.

1. Growth of Staphylococcus aureus (8325; alphai(-)p(+)), constitutive for the production of penicillinase, in CY medium results in about 40% of the enzyme being free in the medium. By modifying the medium, 98% of the enzyme remains cell-bound. 2. Part of this is bound ionically to the surface of the cell wall and may be liberated instantaneously by certain inorganic anions. Maximum liberation was achieved with either phosphate or arsenate, both of which showed marked pH-dependence. 3. Polyanions that do not penetrate the cell wall, such as heparin, RNA and dextran sulphate, are also effective in liberating penicillinase. 4. Polyanions added to the growth medium prevent the appearance of ionically bound penicillinase owing to their strong affinity for the sites on the cell wall required for binding of the enzyme.

Journal Article↗
PubMed2006

Combination therapy with daptomycin, vancomycin, and rifampin for recurrent, severe bone and prosthetic joint infections involving methicillin-resistant Staphylococcus aureus.

Methicillin-resistant Staphylococcus aureus (MRSA) infections are commonly treated with vancomycin (VAN) or another glycopeptide antibiotic. However, when vancomycin fails or infections recur, there are few other therapeutic options. Presented here are 2 cases where a novel combination of daptomycin, vancomycin, and rifampin resolved recurrent MRSA bone and prosthetic joint functions.

Anti-Bacterial Agents↗
PubMed1981

Induction of human gamma interferon by protein A from Staphylococcus aureus.

Protein A from Staphylococcus aureus (SpA) has been observed to stimulate the production of human gamma interferon (HuIFN gamma) by peripheral blood mononuclear cells (MNC). Dose-dependent experiments showed donor-to-donor variation in the concentration of SpA required for maximum IFN production although 50 micrograms/ml consistently produced near peak IFN gamma titers for each donor. Kinetic studies revealed that peak IFN gamma production occurred 24 hr after SpA stimulation. Physicochemical and antigenic characterization showed that SpA-induced IFN possessed the characteristics of IFN gamma in that it was inactivated by treatment at pH 2, heating at 56 C and anti-HuIFN gamma serum but not by anti-HuIFN alpha serum. Further studies showed tha maximum IFN gamma production could be achieved by stimulating 5 x 10(6) MNC/ml and IFN gamma could be harvested for 3 successive days by removing IFN gamma-containing supernatant fluids and adding fresh medium to stimulated MNC cultures. Preliminary cell fractionation studies suggest that the mononuclear cell that produces IFN gamma after SpA stimulation is a nonadherent lymphocyte that lacks high affinity receptors for sheep erythrocytes and expresses Fc receptors for IgG. Moreover, unlike other mitogen inducers, SpA appears to be less dependent on the presence of macrophages for IFN gamma production.

Humans↗
PubMed1971

Serum Bacteriostasis of Staphylococcus aureus.

Serum bacteriostasis of Staphylococcus aureus was characterized quantitatively and quantitatively. Bacteriostasis was proportional to the concentration of serum. Reproducibility was good; freezing and thawing did not materially affect the end point. Four of six different strains, including the propagating S. aureus strain for phage 73 which does not produce coagulase, were susceptible to serum bacteriostasis in similar titers; two were not susceptible at all. All six strains were effective inhibitors of bacteriostasis. Active and inactive coagulase were also inhibitors. In contrast to sensitive S. aureus, S. epidermidis and Streptococcus salivarius were not uniformly susceptible to bacteriostasis by different serums. Escherichia coli, Enterobacter aerogenes, Klebsiella pneumoniae, Salmonella montevideo, S. zymogenes, and Diplococcus pneumoniae were not susceptible. Among gram-positive bacteria, only D. pneumoniae inhibited S. aureus bacteriostasis. Agglutinins of S. aureus and nonspecific substances such as lysozyme, beta-lysin, C-reactive protein, and transferrin were not responsible for S. aureus serum bacteriostasis. After diethylaminoethyl column fractionation of serum, the bacteriostatic principle was eluted in proximity to blood group antibody; immunoglobulins A, G, and M appeared to be present in bacteriostatic fractions. It is suggested that S. aureus bacteriostasis by serum is due to natural antibody and that inhibitory reactions with pneumococci and coagulase are due to common antigens.

Journal Article↗
PubMed1966

Staphylococcus aureus on the hair.

Staphylococcus aureus was found to be present on the hair of about 10% of people having no hospital contact and on that of about 50% of patients with skin diseases. The ;resident' carrier rate was higher in patients with eczema and psoriasis than in others and appeared to be related to carriage of the organisms on the skin. Much of the ;transient' carriage could be attributed to contamination from other sources in the ward.

Carrier State↗
PubMed1980

Stimulation of human lymphocyte subpopulations by protein A from Staphylococcus aureus.

Protein A from Staphylococcus aureus is known to stimulate human lymphocytes. Using 3H-thymidine incorporation, virus plaque assay and induction of cytotoxic T lymphocytes (CTL), this study showed that soluble or insoluble protein A stimulated different lymphocyte subpopulations. Soluble protein A is highly mitogenic to T lymphocytes. In both 3H-thymidine incorporation and virus plaque assay, its maximum stimulation was as high as the stimulation by the nonspecific mitogens phytohemagglutinin and concanavalin A, and a higher CTL response than that induced by phytohemagglutinin or concanavalin A was induced. Mitogenic activity to B lymphocytes was negligible. S. aureus (Cowan I strain) is itself considered to be an insoluble form of protein A and is 3--4 times more mitogenic to B lymphocytes than pokeweed mitogen without any increase in virus plaque-forming cells. No mitogenicity was noted to T lymphocytes. Sepharose CL-4B-protein A, also known as insoluble protein A, stimulated both T and B lymphocytes effectively, but its mitogenicity to T lymphocytes was considered to be due to the soluble protein A released from the Sepharose CL-4B beads.

B-Lymphocytes↗