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PubMed2003

The role of fibronectin binding proteins in the pathogenesis of Staphylococcus aureus infections.

PURPOSE OF REVIEW: Staphylococcus aureus produces two closely-related fibronectin-binding proteins (FnBPs) that facilitate attachment by this versatile pathogen. Recent studies of staphylococcal FnBP have increased our understanding of the molecular mechanisms that are critical in bacterial-host cell interactions and in infection. RECENT FINDINGS: This review will summarize current knowledge of the role of the FnBPs of Staphylococcus aureus in the pathogenesis of infection. The FnBPs, which facilitate attachment of this pathogen to host cells and to fibronectin-coated biomaterials, are important mediators of infection in experimental endocarditis. In addition, recent vaccine studies utilizing FnBP derivatives have shown partial protection in animals. FnBPs also act as invasins permitting uptake of the staphylococcus by cultured non-professional phagocytes using host fibronectin to bridge with integrins on the cell surface. However, the precise role of FnBP in tissue invasion and the relevance of intracellular invasion in disease remain to be elucidated. SUMMARY: FnBP is one of many adhesins expressed by S. aureus that influence host tissue adherence by binding to host fibronectin. FnBP-based vaccine strategies and novel anti-adherence tools based upon FnBP derivatives are in the early stages of investigation but may show promise in preventing staphylococcal infections.

Adhesins, Bacterial↗

PubMed1994

Use of commercial particle agglutination systems for the rapid identification of methicillin-susceptible and methicillin-resistant Staphylococcus aureus.

The performance of a recently introduced Staphylococcus aureus identification system (Slidex Staph-Kit) was compared with that of currently available systems (Immuno Scan Staphlatex, Staphyloslide, Staphaurex and SeroSTAT II) for the identification of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-susceptible Staphylococcus aureus. The new system, which detects a capsular antigen common in MRSA, performed with equal or greater sensitivity than the other systems. None of the commercial systems was adversely affected by the methicillin susceptibility of the staphylococci when isolates were recovered from non-selective media. The greatest advantage of the anti-capsular monoclonal reagent was its improved performance on isolates recovered from selective media.

Humans↗

PubMed2001

[Study of methicillin-resistant Staphylococcus aureus colonization among intermediate-care facility patients].

PURPOSE: Prevalence of methicillin-resistant Staphylococcus aureus is high in the Poitiers teaching hospital, particularly in the intermediate care facilities. We performed a survey of methicillin-resistant Staphylococcus aureus colonization in the intermediate care facilities and 265 patients were included. METHODS: Nasal, cutaneous and wound swab cultures were done at the time of admission and at the time of the patients' departure. A decolonization procedure of methicillin-resistant Staphylococcus aureus carriers was performed using nasal application of fusidic acid and different soaps for the skin. At entry, 17.7% of patients were methicillin-resistant Staphylococcus aureus carriers (of at least one location). At departure, 30.4% were methicillin-resistant Staphylococcus aureus carriers. Among methicillin-resistant Staphylococcus aureus non-carriers at entry, 24.3% became methicillin-resistant Staphylococcus aureus carriers. RESULTS: The principal risk factor of carriage was the initial presence of a wound (RR = 3.6). The incidence rate of methicillin-resistant Staphylococcus aureus infection among the 265 patients included was 3%. CONCLUSION: The systematic screening of patients at the time of admission is expensive and isolation technically hard to manage in the intermediate care facilities. The risk factor we found in this study allow us to propose a 'light' screening limited to patients with wounds.

Aged↗

PubMed1992

Conjugative trimethoprim resistance in Staphylococcus aureus.

A multiply resistant Staphylococcus aureus isolate, WBG7410, harbours plasmids of 38, 26, 2.8, 2.4 and 1.9 kb and transfers trimethoprim and kanamycin resistance at high frequencies by conjugation. The transconjugants contained the 38-kb plasmid, pWBG707, and the 2.8-kb plasmid. Plasmid pWBG707 was shown to encode trimethoprim resistance, was conjugative and mobilised at high frequencies the 2.8-kb plasmid which presumably encodes kanamycin resistance. Plasmid pWBG707 was isolated mostly in the open circular form and analysis with EcoRI restriction endonuclease suggests that pWBG707 is a new conjugative plasmid distinct from the other conjugative plasmids reported in S. aureus.

Conjugation, Genetic↗

PubMed2001

Synergy between Staphylococcus aureus and Pseudomonas aeruginosa in a rat model of complex orthopaedic wounds.

BACKGROUND: We observed an interaction in animals inoculated concomitantly with Staphylococcus aureus and Pseudomonas aeruginosa during a study of the efficacy of surfactants for disinfection of orthopaedic wounds. This led us to investigate whether synergy could be demonstrated between Staphylococcus aureus and Pseudomonas aeruginosa in a rat model of complex orthopaedic wounds. METHODS: A wire was implanted into the spinous process of a lumbar vertebra of Sprague-Dawley rats through a dorsal incision. Animals were divided into two groups: group one was inoculated with either Staphylococcus aureus or Pseudomonas aeruginosa, and group two received a polymicrobial inoculation with both test organisms in varying concentrations. After inoculation, the wounds were irrigated and closed. On postoperative day 14, all animals were killed and specimens from the wounds were cultured. The number of colony-forming units (CFU) of Staphylococcus aureus or Pseudomonas aeruginosa needed to cause infection in 50% of the animals (ID50) was determined with use of the Reed-Muench method. The infection rate associated with each inoculum combination was calculated, and the two groups were compared. RESULTS: The ID50 was 2.8 x 10(4) CFU for Staphylococcus aureus and 4.8 x 10(5) CFU for Pseudomonas aeruginosa. The combination of 10(3) CFU of Staphylococcus aureus with low concentrations (10(2), 10(3), or 10(4) CFU) of Pseudomonas aeruginosa yielded infection rates that were higher than those found with either organism alone at the same concentrations. The combination of 10(3) CFU of Staphylococcus aureus and 10(3) CFU of Pseudomonas aeruginosa yielded a 75% infection rate, which was significantly higher (p = 0.004) than that associated with 10(3) CFU of either organism alone. As the Pseudomonas aeruginosa concentration was increased (to 10(5), 10(6), and 10(7) CFU), this trend reversed, and the infection rate decreased to 33% (p = 0.004). Low concentrations of Pseudomonas aeruginosa (0 to 10(5) CFU) combined with 10(6) CFU of Staphylococcus aureus yielded infection rates ranging from 83% to 100%. At the higher concentrations of Pseudomonas aeruginosa (10(6) and 10(7) CFU), however, the infection rate again decreased, to 33% (p = 0.005). Only Staphylococcus aureus was isolated from the cultures of the specimens from the animals that had received a polymicrobial inoculum. CONCLUSIONS: Synergy between Staphylococcus aureus and Pseudomonas aeruginosa was demonstrated when low levels of each organism were present in the wound. As the Pseudomonas aeruginosa concentration was increased, the infection rates fell well below what would be anticipated, suggesting that low concentrations of Pseudomonas aeruginosa enhance the ability of Staphylococcus aureus to cause infection in this orthopaedic wound model. At the same time, the presence of Staphylococcus aureus in the ratios tested decreased the rate of infection by Pseudomonas aeruginosa. CLINICAL RELEVANCE: Staphylococcus aureus is a pathogen commonly seen in orthopaedic patients. The pathogenicity of Staphylococcus aureus was shown to be increased in the presence of anaerobic bacteria. This study is the first one that we are aware of that demonstrated synergy between Staphylococcus aureus and Pseudomonas aeruginosa, at low concentrations, in a wound model while at the same time showing that Staphylococcus aureus lowers the rate of Pseudomonas aeruginosa infection.

Animals↗

PubMed1992

Association between Staphylococcus aureus nasopharyngeal colonization and septicemia in patients infected with the human immunodeficiency virus.

In an attempt to identify risk factors for Staphylococcus aureus septicemia, 136 consecutive HIV-infected patients were investigated for the presence of nasopharyngeal colonization with Staphylococcus aureus and subsequent Staphylococcus aureus infection. Sixty of 136 (44.1%) HIV-infected patients had staphylococci which were detected in the nasopharynx on initial culture compared to 12 of 39 (30.8%) patients with chronic diseases and 11 of 47 (23.4%) healthy hospital staff. Another 12 HIV-infected subjects proved to be Staphylococcus aureus carriers on follow-up cultures. Patients with full-blown AIDS had a higher carriage rate compared to subjects who were only HIV-positive (p < 0.05), indicating that Staphylococcus aureus colonized patients were more severely ill. Eight patients with Staphylococcus aureus septicemia were observed, all of whom were carriers; no septicemia occurred in the non-colonized patients (p < 0.01). Colonized patients with neutropenia (< 1000/microliters) were significantly more likely to develop septicemia (p < 0.01). Nasopharyngeal colonization with Staphylococcus aureus and the presence of an indwelling catheter were established to be factors that help identify patients at risk of acquiring subsequent Staphylococcus aureus infection.

Adult↗

PubMedDate not supplied

Much ado about nothing: methicillin-resistant Staphylococcus aureus.

The pathogenic methicillin-resistant Staphylococcus aureus (MRSA) has received a voluminous amount of notoriety. The four major reasons are its morbidity, mortality rate, cost of treatment, and constant appearance in intensive care units. Both Staphylococcus aureus and S. epidermidis (MRSE) account for 82% of our gram-positive wound isolates, whereas the gram-negative account for 34% of all isolates. Therefore we compared the morbidity, mortality rate, and cost factors related to MRSA-MRSE and gram-negative infections for a 4-year period, assessing more than 214 documented infections. Morbidity and mortality rates were minor for MRSA. Pseudomonas aeruginosa and Escherichia coli accounted for 57.5% of the total gram-negative isolates. Gram-negative antimicrobial therapy usually requires two therapeutic drugs, which increases morbidity and costs, whereas the staphylococci usually can be treated by one antimicrobial. During this period there were 47 gram-negative infections requiring 10 to 15 additional days of hospital stay, with a daily antibiotic cost of $293.40. Costs for MRSA or MRSE are 28% less. Therefore our preoccupation with MRSA or MRSE infections is unwarranted and unsubstantiated.

Adolescent↗

PubMed1986

Experimental mandibular Staphylococcus aureus osteomyelitis; antibody response and treatment with dicloxacillin.

Staphylococcus aureus mandibular osteomyelitis was produced in 20 rabbits by injection of a sclerosing agent and 1 X 10(9) colony-forming units of Staphylococcus aureus V8 into the medullary cavity of the mandible. After 2 weeks all rabbits developed infections. 10 of the rabbits were then treated with dicloxacillin (22.5 mg/kg body weight) every 12 h for 7 days and 10 were left untreated. The animals were sacrificed after 8 weeks and histopathological examination was performed. An enzyme-linked immunosorbent assay (ELISA) was used to measure IgG response against staphylococcal teichoic acid and alpha-toxin during the observation period. In the treated group, there was a decrease in clinical symptoms after the treatment period, while in the untreated group, progression of the infection was a common finding. At the end of the treatment period, Staphylococcus aureus V8 could not be recovered from aspirates obtained from animals in the treatment group, while in the non-treatment group, Staphylococcus aureus V8 could be recovered from abscesses in 6 rabbits. Both in the treated group and in the untreated group, the rabbits showed increasing IgG titers against teichoic acid and alpha-toxin during the first 2-3 weeks. No significant differences in antibody response patterns were noted between the treated and untreated groups and no clear correlation between the immunological response and the severity of the disease was observed.

Animals↗

PubMed2006

Therapies and vaccines for emerging bacterial infections: learning from methicillin-resistant Staphylococcus aureus.

Methicillin-resistant Staphylococcus aureus (MRSA) is an emerging bacterial infection worldwide, and community-acquired MRSA (CA-MRSA) infection, which has increased dramatically in frequency in many areas, is of particular clinical and public health concern. CA-MRSA outbreaks and severe infections have been reported more frequently in children, often manifesting in one of two distinct clinical syndromes, furunculosis or necrotizing pneumonia. This article outlines the molecular biology of MRSA, how molecular biology has contributed to the understanding of MRSA infections, current therapy and prevention of MRSA, and the prospects for a vaccine against S aureus.

Anti-Bacterial Agents↗

PubMed2003

[Staphylococcus aureus, a successful pathogen].

Staphylococcus aureus is a dreadful pathogen for mankind, causing boils, abscesses, wound infections, osteomyelitis, septicaemia, endocarditis, pneumonia, toxic shock syndrome, scalded skin syndrome, and food poisoning. The development of penicillin-, methicillin-, and vancomycin-resistant strains shows that S. aureus has an enormous adaptive power. Most methicillin-resistant strains of S. aureus (MRSA) are hospital-acquired, although an increasing number are reported to be community-acquired. A limited number of clones of MRSA have spread all over the world. Since most community-acquired MRSA can be traced back to some contact with health care, MRSA can still best be combatted by control measures in health care institutions. In this respect, the Netherlands and Scandinavian countries have been very successful so far. S. aureus has many virulence factors at its disposal: structural components, enzymes and three types of toxins. Panton-Valentine leukocidin (PVL) has received attention as a factor causing severe pneumonia with high mortality. A strain combining methicillin resistance and PVL has spread through France. Recently, the genome of an MRSA strain has been unravelled. Its structure illustrates how well S. aureus can adapt itself and acquire properties of other microorganisms. This genetic knowledge may lead to new strategies to combat S. aureus.

Adaptation, Physiological↗

PubMed2000

Evaluation of a latex agglutination assay for rapid detection of oxacillin resistant Staphylococcus aureus.

Oxacillin resistance in Staphylococcus aureus is mediated by the mecA gene, resulting in production of penicillin-binding protein 2a (PBP2a), which is not present in the oxacillin susceptible strains. We evaluated the ability of a 30-min latex agglutination (LA) test (Seiken, Tokyo, Japan) to detect production of PBP2a in 315 clinical isolates of S. aureus. The LA results were compared with results of susceptibility testing using the Vitek GPS-SV test card. The latex test was positive for all 206 isolates determined to be methicillin resistant by Vitek (sensitivity 100%), the latex test was negative for 108 of 109 isolates determined to be oxacillin susceptible by Vitek, and the latex test was positive for 1 isolate determined to be susceptible by Vitek (specificity 99.1%). The discrepant isolate was negative for the mecA gene by polymerase chain reaction (PCR). The LA test is a rapid and reliable method for detecting oxacillin resistant S. aureus.

Evaluation Studies as Topic↗

PubMed1992

Role of fibronectin in the adherence of Staphylococcus aureus to dermal tissues.

Staphylococcus aureus has a fibronectin receptor on its surface. Fibronectin seems to play a role in the initiation and modification of infection with S. aureus. We studied the role of fibronectin in the binding of S. aureus (clinical isolates) to dermal tissues in mice, and the relationship between the fibronectin binding ability of S. aureus and clinical features of S. aureus skin infections. Mice were inoculated with S. aureus incubated with gold-particles bound fibronectin and skin specimens were taken for electron microscopic examination. The number of gold particles surrounding the S. aureus cells decreased with time, with none detected 4 h after inoculation. At both 5 min and 1 h after inoculation, gold particles were only found on the free surface of S. aureus cells and not in the interface between S. aureus cells and fibroblasts. Fibronectin-bound gold particles were bound more extensively to S. aureus strains isolated from furunculosis or furuncle than to those from bullous impetigo. These results suggest that the matrix fibronectin on the surface of the fibroblasts of mice contributes to the adherence of S. aureus to the fibroblasts, and that the number of fibronectin binding sites on S. aureus cells is related to the degree of local invasiveness.

Animals↗

PubMedDate not supplied

Effects of chlorhexidine gluconate and chlorous acid-chlorine dioxide on equine fibroblasts and Staphylococcus aureus.

Equine fibroblasts and Staphylococcus aureus were exposed for 30 minutes to six dilutions of chlorhexidine gluconate, a chlorous acid-chlorine dioxide irrigation solution, a chlorous acid-chlorine dioxide disinfectant, and phosphate buffered saline controls. Cell viability was determined by trypsinizing the cells, staining them with trypan blue, and counting cells that did not take the stain. All fibroblasts were killed when exposed to 1.0% and 0.5% chlorhexidine. The survival rate of fibroblasts increased linearly with decreasing concentrations of chlorhexidine gluconate, with a peak survival of 50% at 0.005% chlorhexidine. The chlorous acid-chlorine dioxide irrigation solution was the least toxic to fibroblasts, with survival rates equivalent to those of controls. The chlorous acid-chlorine dioxide disinfectant was 100% cytotoxic even when diluted 1:1 with phosphate buffered saline. S. aureus growth was inhibited by 1.0% and 0.5% chlorhexidine gluconate; concentrations of 0.05%, 0.01%, and 0.005% did not differ from sterile water controls. The chlorous acid-chlorine dioxide irrigation solution did not inhibit growth of S. aureus in brain-heart infusion broth. The chlorous acid-chlorine dioxide disinfectant inhibited growth of S. aureus.

Animals↗

PubMed2004

Staphylococcus aureus: superbug, super genome?

Staphylococcus aureus is a common cause of infection in both hospitals and the community, and it is becoming increasingly virulent and resistant to antibiotics. The recent sequencing of seven strains of S. aureus provides unprecedented information about its genome diversity. Subtle differences in core (stable) regions of the genome have been exploited by multi-locus sequence typing (MLST) to understand S. aureus population structure. Dramatic differences in the carriage and spread of accessory genes, including those involved in virulence and resistance, contribute to the emergence of new strains with healthcare implications. Understanding the differences between S. aureus genomes and the controls that govern these changes is helping to improve our knowledge of S. aureus pathogenicity and to predict the evolution of super-superbugs.

Drug Resistance, Bacterial↗

PubMedDate not supplied

Shear stress affects the kinetics of Staphylococcus aureus adhesion to collagen.

Staphylococcus aureus is a major human pathogen that has been shown to bind collagen under static conditions. However, many staphylococcal infections are hematogenously acquired and adhesion events may be influenced by shear stress. In this study, we used a dynamic experimental system consisting of a parallel-plate perfusion chamber and phase-contrast video microscope to study the effects of shear stress on the adhesion kinetics of intact S. aureus to collagen surfaces in vitro. The adhesion of S. aureus Phillips to collagen types I, II, and IV was investigated over a physiologically relevant range of wall shear stresses at 37 degrees C. S. aureus PH100, a collagen adhesin-deficient mutant strain, was used as a control strain for the experiments. We found that S. aureus Phillips could adhere to collagens I, II, and IV at wall shear stresses less than 15 dyn/cm(2) and that the kinetics of the adhesion process were wall shear stress-dependent. Similar studies with PH100 demonstrated that these cells are unable to adhere firmly to collagen surfaces. Transient interactions between PH100 and the collagen surfaces were observed at low levels of shear stress suggesting that S. aureus may also interact with collagen by an alternative mechanism that does not lead to firm adhesion.

Bacterial Adhesion↗

PubMed1986

Specific attachment of Staphylococcus aureus to immobilized fibronectin.

Staphylococcus aureus cells have been shown to possess surface-associated proteins with affinity for soluble fibronectin. We have investigated the ability of these surface proteins to mediate attachment to immobilized fibronectin and collagen. Attachment was quantified by determination of bacterial ATP in a bioluminescence assay. The ability to attach to fibronectin- or collagen-coated plastic surfaces was investigated for four S. aureus strains: Cowan 1, Newman, SA113(83A), and Wood 46. Cells from the different strains varied in their attachment properties, but all cells except those of strain Wood 46 attached readily to substrates coated with fibronectin. Only cells from strain Cowan 1 attached reproducibly to collagen-coated substrates in the absence of fibronectin. The attachment of cells from strain SA113(83A) to fibronectin-coated surfaces was shown to be dependent on time, fibronectin concentration, and bacterial growth phase. Soluble fibronectin or NH2-terminal fibronectin fragment (Mr, 29,000) disturbed the attachment to surfaces coated with fibronectin bound to denatured collagen type I. The attachment process to such substrates was also effectively inhibited by preincubating the substrate with fibronectin-binding proteins isolated from S. aureus Newman and SA113 (83A) and purified with affinity chromatography.

Amino Acid Sequence↗

PubMed1999

Impact of the high-affinity proline permease gene (putP) on the virulence of Staphylococcus aureus in experimental endocarditis.

Staphylococcus aureus causes a wide variety of invasive human infections. However, delineation of the genes which are essential for the in vivo survival of this pathogen has not been accomplished to date. Using signature tag mutagenesis techniques and large mutant pool screens, previous investigators identified several major gene classes as candidate essential gene loci for in vivo survival; these include genes for amino acid transporters, oligopeptide transporters, and lantibiotic synthesis (W. R. Schwan, S. N. Coulter, E. Y. W. Ng, M. H. Langhorne, H. D. Ritchie, L. L. Brody, S. Westbrock-Wadman, A. S. Bayer, K. R. Folger, and C. K. Stover, Infect. Immun. 66:567-572, 1998). In this study, we directly compared the virulence of four such isogenic signature tag mutants with that of the parental strain (RN6390) by using a prototypical model of invasive S. aureus infection, experimental endocarditis (IE). The oligonucleotide signature tag (OST) mutant with insertional inactivation of the gene (putP) which encodes the high-affinity transporter for proline uptake exhibited significantly reduced virulence in the IE model across three challenge inocula (10(4) to 10(6) CFU) in terms of achievable intravegetation densities (P, <0.05). The negative impact of putP inactivation on in vivo survival in the IE model was confirmed by simultaneous challenge with the original putP mutant and the parental strain as well as by challenge with a putP mutant in which this genetic inactivation was transduced into a distinct parental strain (S6C). In contrast, inactivation of loci encoding an oligopeptide transporter, a purine repressor, and lantibiotic biosynthesis had no substantial impact on the capacity of OST mutants to survive within IE vegetations. Thus, genes encoding the uptake of essential amino acids may well represent novel targets for new drug development. These data also confirm the utility of the OST technique as an important screening methodology for identifying candidate genes as requisite loci for the in vivo survival of S. aureus.

Amino Acid Transport Systems, Neutral↗

PubMed2006

Evidence for clonal evolution among highly polymorphic genes in methicillin-resistant Staphylococcus aureus.

The evolution of Staphylococcus aureus has been described as predominantly clonal, based on evidence from seven housekeeping genes. We aimed to test if this was also true for more polymorphic genes. In a collection of 60 isolates including major European epidemic methicillin-resistant S. aureus (MRSA) and sporadic MRSA strains, we compared the partial gene sequences of seven housekeeping genes (arcC, aroE, glpF, gmk, pta, tpi, and yqiL), six core adhesion genes (present in all strains) (clfA, clfB, fnbA, map, sdrC, and spa), and four accessory adhesion genes (not present in all strains) (ebpS, fnbB, sdrD, and sdrE). Nucleotide diversity of adhesion genes was 2- to 10-fold higher than genes used for multilocus sequence typing. All genes showed evidence for purifying selection with a weakly reduced level among accessory adhesion genes. Among these highly variable genes, there was no evidence for a difference in molecular evolution between epidemic and sporadic strains. Gene trees constructed from concatenated sequences of housekeeping, core adhesion, and accessory adhesion genes were highly congruent, indicating clonality, despite some evidence for homologous exchange. Further evidence for clonality was found with an overall positive correlation of allelic and nucleotidic divergence for both seven housekeeping genes and six core adhesion genes. However, for small allelic differences that fit the demarcations of clonal complexes (CCs) there was no such correlation, suggesting that recombination occurred. Therefore, despite an overall clonal population structure, recombination between related isolates within CCs might have contributed to S. aureus evolution.

Bacterial Proteins↗