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PubMed1997

Interaction of von Willebrand factor with Staphylococcus aureus.

Intravascular infection due to Staphylococcus aureus requires colonization of subendothelium in the presence of shear forces. von Willebrand factor (VWF) is a large multimeric glycoprotein playing a key role in platelet adhesion to subendothelium. To determine whether VWF may also play a role in adhesion of S. aureus to endovascular sites, binding of VWF to S. aureus and adhesion of S. aureus to VWF-adsorbed substrates was examined. Binding isotherms revealed a dose-dependent reaction of purified VWF with S. aureus Cowan 1 as well as VWF binding to other S. aureus strains. On solid phase, VWF showed saturable adsorption kinetics to polymethylmethacrylate and promoted S. aureus adhesion up to 67-fold in a trypsin-sensitive reaction. Similar adhesion promotion was observed when recombinant VWF was used. These results show that VWF interacts with S. aureus in suspension and promotes S. aureus adhesion to surfaces, suggesting a role of VWF in the pathogenesis of intravascular S. aureus infections.

Bacterial Adhesion↗
PubMed1989

Growth and production of enterotoxin A by Staphylococcus aureus in cream.

Behavior of Staphylococcus aureus strains 100-A, 196-E, 254, 473, 505, and 521 in sweet (18 to 80% milk fat) and neutralized sour cream was studied. Cream was inoculated to contain approximately 10(3) to 10(4) S. aureus/ml, depending on milk fat content, and was incubated at 4, 22, or 37 degrees C. Determinations were made of aerobic plate count, S. aureus count, and pH. When growth in cream exceeded 10(7) S. aureus/ml, enterotoxin analysis was done. Sweet and neutralized sour cream supported growth of all strains of S. aureus tested. Strains 100-A, 196-E, 473, 505, and 521 grew sufficiently to produce enterotoxin in sweet cream of 18 or 32% milk fat held at 37 degrees C for 18 h or at 22 degrees C for 52 h. Populations of strains 100-A, 196-E, 505, and 521 exceeded 10(6) cells/ml in sweet cream of 36% milk fat held for 18 h at 37 degrees C. Strains 100-A and 521 grew to more than 10(6) cells/ml in sweet cream of 40% milk fat held for 18 h at 37 degrees C. No strain of S. aureus grew to levels associated with detectable enterotoxin production at 4 degrees C within 14 d in any cream. Incubation temperature, milk fat content of cream, and variation among strains influenced the ability of S. aureus to grow and produce enterotoxin.

Aerobiosis↗
PubMed2002

The effect of antibiotics on the production of superantigen from Staphylococcus aureus isolated from atopic dermatitis.

Staphylococcus aureus (S. aureus) often colonizes on the skin of patients with atopic dermatitis. It is known that superantigens which are staphylococcal enterotoxins can activate T cells without processing by antigen presenting cells. It has been suggested that activated T cells release various cytokines which may exacerbate or prolong the cutaneous inflammation associated with atopic dermatitis. Reduction of bacterial colonization from skin lesions has been reported to be effective in the treatment of atopic dermatitis. Therefore, antimicrobial therapy using antibiotics may be a treatment option for atopic dermatitis in selected patients. We examined the effect of antibiotics on the production of superantigen from S. aureus in vitro to determine the action mechanism of antibiotics in the treatment of atopic dermatitis. It was found that antibiotics with inhibitory effect on protein synthesis can suppress the production of superantigen. On the other hand, the superantigen production was not suppressed by antibiotics having either the inhibitory effect on cell wall synthesis or on nucleic acid synthesis. Levels of the suppressive effect on superantigen production by S. aureus varied with strains tested in this study. Moreover, we demonstrated that replication of DNA coding of superantigen produced by S. aureus was suppressed only by roxithromycin (ROX), which is a new macrolide. This finding suggests that ROX may have an effect at the gene level. These results suggested that the suppressive effects of antimicrobial agents that act as inhibitors of protein synthesis on superantigen production from S. aureus may be useful in the treatment of atopic dermatitis.

Anti-Bacterial Agents↗
PubMed2006

Nose picking and nasal carriage of Staphylococcus aureus.

OBJECTIVE: Nasal carriage of Staphylococcus aureus is an important risk factor for S. aureus infection and a reservoir for methicillin-resistant S. aureus. We investigated whether nose picking was among the determinants of S. aureus nasal carriage. SETTING AND PARTICIPANTS: The study cohort comprised 238 patients who visited the ear, nose, and throat (ENT) disease outpatient clinic of a tertiary care hospital and did not have a nose-specific complaint (defined as ENT patients) and 86 healthy hospital employees (including medical students and laboratory personnel). MEASUREMENTS: All participants completed a questionnaire on behavior regarding the nose and were screened for S. aureus nasal carriage; only ENT patients underwent nasal examination by an ear, nose, and throat physician for clinical signs of nose picking. RESULTS: Among ENT patients, nose pickers were significantly more likely than non-nose pickers to carry S. aureus (37 [53.6%] of 69 vs 60 [35.5%] of 169 patients; relative risk, 1.51 [95% confidence interval, 1.03-2.19]). Among healthy volunteers, there was a statistically significant positive correlation between the self-perceived frequency of nose picking and both the frequency of positive culture results (R=0.31; P=.004) and the load of S. aureus present in the nose (R=0.32; P=.003). CONCLUSION: Nose picking is associated with S. aureus nasal carriage. The role of nose picking in nasal carriage may well be causal in certain cases. Overcoming the habit of nose picking may aid S. aureus decolonization strategies.

Adult↗
PubMedDate not supplied

Surface proteins of Staphylococcus aureus.

Crude cell walls of Staphylococcus aureus of potential immunologic or epidemiologic importance were prepared for study by mechanically disrupting whole cells and applying differential centrifugation. Cell-wall proteins were then released from the wall by lysostaphin digestion and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Distinct electrophoretic protein patterns were found for each of the 12 serologically distinct strains examined. There were two major groups of cell-wall proteins identified in the 45-57-kilodalton (kdal) and 100-190-kdal range, respectively. Proteins in the 45-57-kdal range appeared to represent protein A variants of different apparent molecular mass. Localization experiments with 125I labeling demonstrated the surface location of most of the proteins. These data suggest that selected surface-exposed proteins may be important in defining host immune responses to S. aureus infections.

Autoradiography↗
PubMed2001

Diminished virulence of an alpha-toxin mutant of Staphylococcus aureus in experimental brain abscesses.

Staphylococcus aureus is one of the major etiologic agents of brain abscesses in humans, occasionally leading to focal neurological deficits and even death. The objective of the present study was to identify key virulence determinants contributing to the pathogenesis of S. aureus in the brain using a murine brain abscess model. The importance of virulence factor production in disease development was demonstrated by the inability of heat-inactivated S. aureus to induce proinflammatory cytokine or chemokine expression or brain abscess formation in vivo. To directly address the contribution of virulence determinants in brain abscess development, the abilities of S. aureus strains with mutations in the global regulatory loci sarA and agr were examined. An S. aureus sarA agr double mutant exhibited reduced virulence in vivo, as demonstrated by attenuated proinflammatory cytokine and chemokine expression and bacterial replication. Subsequent studies focused on the expression of factors that are altered in the sarA agr double mutant. Evaluation of an alpha-toxin mutant revealed a phenotype similar to that of the sarA agr mutant in vivo, as evidenced by lower bacterial burdens and attenuation of cytokine and chemokine expression in the brain. This suggested that alpha-toxin is a central virulence determinant in brain abscess development. Another virulence mechanism utilized by staphylococci is intracellular survival. Cells recovered from brain abscesses were shown to harbor S. aureus intracellularly, providing a means by which the organism may establish chronic infections in the brain. Together, these data identify alpha-toxin as a key virulence determinant for the survival of S. aureus in the brain.

Animals↗
PubMed2006

Application of molecular techniques in the study of Staphylococcus aureus clonal evolution--a review.

Staphylococcus aureus is an important agent of healthcare-associated and community-acquired infections. A major characteristic of this microorganism is the ability to develop resistance to antimicrobial agents. Several molecular techniques have been applied for the characterization of S. aureus in epidemiological studies. In the present review, we discuss the application of molecular techniques for typing S. aureus strains and describe the nomenclature and evolution of epidemic clones of this important pathogen.

Bacterial Typing Techniques↗
PubMed1991

Comparison between lactoferrin and subepithelial matrix protein binding in Staphylococcus aureus associated with bovine mastitis.

Staphylococcus aureus strains (n = 100) isolated from bovine mastitis were classified according to the presence of capsular polysaccharide serotype 5 (n = 46), type 8 (n = 26), and non-5/8 (n = 28). Strains from each type were tested for protein interaction in a 125I-labeled ligand binding assay. A majority of type 5 and type 8 strains showed a higher degree of binding to lactoferrin, fibronectin, and IgG than the non-5/8 strains. Fibrinogen binding was low in all serotypes. Most of the type 5 and non-5/8 strains bound less than 10% laminin, whereas type 8 strains bound laminin in the 11 to 20% range. Non-5/8 strains significantly differed from type 5 in lactoferrin, fibronectin, fibrinogen, and IgG and also from type 8 in fibrinogen and IgG binding. The differences in protein binding between type 5 and type 8 were nonsignificant. The degree of lactoferrin binding in all types positively correlated with laminin binding. Lactoferrin and fibrinogen bindings were correlated in type 5 and type 8 strains. Lactoferrin and fibronectin bindings were correlated only in type 5 strains. These data suggest that bovine lactoferrin binding is common and associated with subepithelial matrix protein interactions in certain serotypes of S. aureus.

Animals↗
PubMed2002

New methods to investigate infectious disease transmission and pathogenesis--Staphylococcus aureus disease in drug users.

Staphylococcus aureus is the single most important bacterial pathogen in infections among drug users. It is responsible for several diseases, ranging from superficial cutaneous abscesses to life-threatening intravascular infections. Although the nature of these infections is well described in published work, there is limited understanding of their epidemiology and pathogenesis. This limitation is in part due to the difficulty of studying disease transmission among drug users in the community, and the limitations of the investigative tools that have so far been used. We review the current understanding of the pathogenesis of staphylococcal disease in drug users and argue for the integration of molecular epidemiological techniques and social network methodology to increase our understanding of the basis for the persistence, distribution, and transmission dynamics of S aureus among drug users. Finally, we propose a framework for investigating the transmission of pathogens in community-based settings.

HIV Infections↗
PubMed2003

Evidence for the absence of Staphylococcus aureus in land applied biosolids.

Staphylococcus aureus is an important human pathogen both within the hospital setting and as a community-acquired infection. Recently there has been concern that land applied biosolids may transmit S. aureus. However, no scientific data are available to document whether biosolids are a source of S. aureus. To determine if S. aureus is present in biosolids, we collected samples from 15 sites across the United States. Samples analyzed were as follows: 3 raw untreated sewage samples and 2 undigested primary sewage sludge samples; 23 different biosolid samples; and 27 aerosols obtained during biosolid land application (biosolid aerosols). Although S. aureus were detected in raw sewage samples, none were found in any of the treated biosolids nor in any biosolid aerosol samples. These results suggest that biosolids are not a likely source of S. aureus human exposure or infection.

Aerosols↗
PubMed1993

[Methicillin resistance, production of toxic shock syndrome toxin-1 and types of enterotoxin, protease and coagulase at vaginal isolates of Staphylococcus aureus].

The vaginal colonization with Staphylococcus aureus, including strains that have methicillin resistance and production of toxic shock syndrome toxin-1 (TSST-1), enterotoxins and protease was studied in 308 women at the time of delivery. Thirty-six of these women were colonized with S. aureus in the vagina. All of the isolates were methicillin sensitive S. aureus (MSSA), except one women who had both methicillin resistant S. aureus (MRSA) and MSSA. The strains, included MRSA, did not elaborate the TSST-1 and produced protease. The distribution of protease pattern (types) observed by MSSA strains on standard methods caseinate agar plates was type A, 1 strain; type B, 15 strains; type C, 6 strains; type D, 14 strains. Sixteen of the 36 strains produced non of the enterotoxins and 20 strains produced enterotoxins and the type distribution was enterotoxin type A, 6 strains; type B, 10 strains; type C, 1 strain; A and B, 1 strain; A, B and C, 2 strains. These results provide the possibility of pathogenic S. aureus colonized in vagina transmit to neonates at the time of delivery.

Adolescent↗
PubMed1979

Oxacillin-induced lysis of Staphylococcus aureus.

Six clinical isolates of Staphylococcus aureus were compared for their relative susceptibilities to the killing effects of oxacillin. Three of the strains had minimum bactericidal concentrations which were >10 times the minimum bacteriostatic concentration for this antibiotic and were designated tolerant (Tol(+)). The other strains had minimum bactericidal concentrations which were comparable to the minimum bacteriostatic concentration (Tol(-)). Lysis curves of these strains revealed that the Tol(+) strains exhibited a diminished rate of lysis when inhibited by oxacillin. This reduced rate of lysis was reflected also in a reduced rate of viability loss when the cells were exposed to oxacillin. During log growth the uptake of [(14)C]glycerol by Tol(+) cells was 1.5-fold greater than that by Tol(-) cells. Glycerol-labeled cells of each phenotype secreted radioactivity when inhibited by oxacillin. However, the Tol(+) strains released over twice as much label as the Tol(-) strains. No difference in the proportion of lipid secreted by the two phenotypes was found. The behavior of 60 to 65% of the labeled material released by inhibited cells during both sodium dodecyl sulfate gel electrophoresis and Sepharose 6B chromatography corresponded to that of lipoteichoic acid. When the major component of secreted material was added to oxacillin-inhibited Tol(-) strains, an inhibition of the lytic response was observed. These results suggest that oxacillin tolerance in S. aureus could be related to the enhanced secretion of an autolysin inhibitor, such as lipoteichoic acid.

Bacteriolysis↗
PubMed1994

Antibacterial activity of human mononuclear leukocytes against Staphylococcus aureus.

Human mononuclear leukocytes kill Staphylococcus aureus cells in vitro. The killing of the bacteria takes place even in the absence of antibodies. The presence of antibodies (in an autologous inactivated serum) usually enhances the antibacterial activity of mononuclear leukocytes. In some cases, however, this activity is markedly decreased by the serum, probably depending of the spectrum of antibodies contained in the serum. The antibacterial activity of mononuclear leukocytes is mostly due to monocytes because their depletion causes substantial drop or the activity disappearance. We failed to demonstrate in the case of S. aureus the antibacterial cytotoxicity of T lymphocytes described by some authors dealing with Gram-negative bacteria. Large differences in the structure of the bacterial cell wall underlie apparently the different sensitivity of G+ and G- bacteria to some protective mechanisms of the host. In the antibacterial assay against S. aureus, electron microscopy revealed a maximal activation of monocytes which phagocytized the bacteria although extracellular killing is not excluded. Electronoptical findings point also to a possible participation of NK cells in the antibacterial cytotoxicity against S. aureus.

Adult↗
PubMed1993

Higher overall nosocomial infection rate because of increased attack rate of methicillin-resistant Staphylococcus aureus.

BACKGROUND: Methicillin-resistant Staphylococcus aureus has become a frequent cause of hospital-acquired infectious disease. However, the impact of methicillin-resistant S. aureus on the overall nosocomial infection rate has not been clearly defined. METHODS: The University of Alabama at Birmingham Hospital is a tertiary care facility and participant in the National Nosocomial Infections Surveillance system. Prospective, hospital-wide surveillance for nosocomial infections was conducted for 8 months per year during 1986 through 1991. RESULTS: The total nosocomial infection rate increased from 4.5% in 1987 to 5.9% in 1990. This was temporally associated with a rise in the attack rate of methicillin-resistant S. aureus from 0% to 0.4%. The remainder of the increase was caused by other gram-positive microorganisms, including methicillin-sensitive S. aureus. We identified methicillin-resistant S. aureus most commonly in the surgical intensive care unit and as a cause of lower respiratory tract infections. In contrast, methicillin-sensitive S. aureus was most frequently found in the neurologic intensive care unit and as the etiologic agent of surgical wound infections. CONCLUSIONS: Methicillin-resistant S. aureus has become a common nosocomial pathogen. There has been no decrease in the attack rate of methicillin-sensitive S. aureus or other gram-positive cocci. The total nosocomial infection rate has increased as a result equally of the emergence of methicillin-resistant S. aureus and of the renewed activity of other gram-positive pathogens. Methicillin-resistant S. aureus has added to the overall burden of nosocomial infectious disease.

Alabama↗
PubMed2001

Fibronectin and fibrinogen contribute to the enhanced binding of Staphylococcus aureus to atopic skin.

BACKGROUND: Staphylococcus aureus colonizes the skin lesions of more than 90% of patients with atopic dermatitis (AD). The mechanism for increased S aureus colonization in AD is unknown. However, the initial event in colonization requires adherence of S aureus to the skin. OBJECTIVE: The purpose of this study was to examine the roles of various bacterial adhesins on S aureus binding to AD skin. METHODS: In an attempt to delineate the mechanism behind this adherence process, an in vitro bacterial binding assay was developed to quantitate the adherence of various S aureus strains to AD, psoriatic, and normal skin sections. S aureus strains used in this study were obtained either from cultures of AD skin lesions or from genetically manipulated strains of S aureus that lacked specific microbial surface components recognizing adhesive matrix molecules (MSCRAMMs)--namely, fibronectin-binding protein (Fnbp), fibrinogen-binding protein (Clf), collagen-binding protein (Cna), and their parent strains. In addition, S aureus strains from patients with AD were pretreated with fibronectin or fibrinogen to block MSCRAMM receptors and interfere with binding. RESULTS: Under all experimental conditions, binding of S aureus was localized primarily to the stratum corneum. Immunocytochemical staining of AD skin sections showed a redistribution of fibronectin to the cornified layer, an observation not seen in normal skin. S aureus binding to uninvolved AD skin was significantly greater than the binding to uninvolved psoriatic skin (P <.0001) and normal skin (P <.0005). The Fnbp-negative S aureus showed a significant reduction in binding to the AD skin (P <.0001) but not to the psoriatic and normal skin. In the AD skin, a significant reduction in the binding of S aureus was also observed in the Clf-negative strain (P <.0001) but not in the Cna-negative S aureus. Preincubation of S aureus with either fibronectin or fibrinogen also inhibited bacterial binding to AD skin (P <.0001). CONCLUSION: These data suggest that fibronectin and fibrinogen--but not collagen--play a major role in the enhanced binding of S aureus to the skin of patients with AD.

Bacterial Adhesion↗
PubMed1985

Growth and enterotoxin production of Staphylococcus aureus in shrimp.

Strains of Staphylococcus aureus isolated from shrimp were examined for phage pattern and enterotoxin production; 63% of the strains isolated from North Sea shrimp were typable with the International and additional set of phages, as were 38% of the strains isolated from South-East Asian shrimp. Staphylococcal enterotoxin(s) (SE) were produced by 48% and 35% of strains isolated from North Sea and South-East Asian shrimp respectively. Growth and enterotoxin production by S. aureus in shrimp was examined in storage experiments at 22 degrees C. S. aureus increased by 1-2 log units in 24 h when the organism was only a minor part of the total microflora of shrimp. When S. aureus was an equivalent part of the total flora its numbers increased by 3-4 log units in 24 h. Enterotoxins A and B became detectable when the number of S. aureus exceeded 10(7) per g in aseptically peeled shrimp. Results indicate that S. aureus is able to produce enterotoxin in shrimp, but its production depends upon a number of factors, including the relationship between S. aureus and competitive micro-organisms. It is concluded that the presence of S. aureus on commercially produced shrimp represents a potential hazard to health.

Animals↗
PubMed2000

In vivo deletion of the methicillin resistance mec region from the chromosome of Staphylococcus aureus strains.

Two sets of Staphylococcus aureus isolates recovered from two patients exhibited similar susceptibility profiles except for oxacillin susceptibility (MSSA) or resistance (MRSA). SMA:I macrorestriction and inter-IS256 PCR analysis showed patterns closely related to the Belgian epidemic MRSA clone 1 in each pair of MSSA/MRSA strains. Loss of one large SMA:I DNA fragment and concurrent gain of a smaller fragment in the MSSA isolates was observed. The mecA sequence present in the MRSA was absent in the MSSA variant. Therefore, in vivo deletion of the mec region may occur in some lineages of S. aureus more frequently than previously thought.

Bacterial Proteins↗