Detection of sasX Gene and Distribution of SCCmec Types in Invasive and Non-invasive Coagulase-negative Staphylococci

Background: Coagulase-negative staphylococci, which belong to the normal microbiota of the skin and mucous membranes, are opportunistic pathogens. sasX, a newly described protein, is thought to play an important role in nasal colonization and methicillin-resistant Staphylococcus aureus virulence, and it may be acquired from coagulase-negative staphylococci by horizontal gene transfer. It has been considered that understanding the function of sasX gene may help clarify the relevance of the different adhesion mechanisms in the pathogenesis of infections associated with biofilm. Aims: To investigate the sasX gene presence, staphylococcal cassette chromosome mec types, and antimicrobial resistance patterns of invasive and noninvasive coagulase-negative staphylococci isolates. Study Design: Cross-sectional study. Methods: The study included a total of 180 coagulase-negative staphylococci strains. Non-invasive isolates (n=91) were obtained from the hands of healthy volunteers who do not work at the hospital (n=30), the nasal vestibule of healthy volunteer hospital workers (n=26), and central venous catheter (n=35). Invasive isolates (n=89) were isolated from peripheral blood cultures of inpatients who do not have catheters. All isolates were identified by conventional microbiological methods, automated systems, and, if needed, with matrix-assisted laser desorption/ionization-time of flight. Staphylococcal cassette chromosome mec typing, sasX and mec gene detection, antibiotic susceptibility, and sasX gene sequence analysis were performed. Results: Peripheral blood, central venous catheter colonization, and nasal vestibule isolates were positive for the sasX gene, whereas hand isolates were negative. sasX gene was present in 17 isolates, and no statistical significance was found between invasive and noninvasive isolates (p=0.173). Sequence analysis of the sasX genes showed high homology to related proteins of Staphylococcus phage SPbeta-like and Staphylococcus epidermidis RP62A. staphylococcal cassette chromosome mec type V was the most prevalent regardless of species. staphylococcal cassette chromosome mec type II was more frequent in invasive isolates and found to be statistically important for invasive and noninvasive S. epidermidis isolates (p=0.029). Staphylococcus haemolyticus isolates had the overall highest resistance rates. Resistance to ciprofloxacin, trimethoprim-sulfamethoxazole, and erythromycin was found to be higher in isolates from catheter and blood culture. Staphylococcus hominis isolates had the highest rate for inducible clindamycin resistance. None of the isolates were resistant to vancomycin, teicoplanin, and linezolid. Conclusion: The sasX gene is detected in 9.44% of the isolates. There is no statistical difference between the sasX-positive and -negative isolates in terms of antibacterial resistance and the presence of sasX and SCCmec types. Further studies about the role of sasX at virulence in coagulase-negative staphylococci, especially from clinical samples such as tracheal aspirate and abscess isolates, and distribution of staphylococcal cassette chromosome mec types are needed.

Evidence of latent molecular diversity determining the virulence of community-associated MRSA USA300 clones in mice.

INTRODUCTION: The USA300 clone of community-associated MRSA is reported to be hypervirulent and epidemic in the United States. This clone causes a variety of diseases from lethal pneumonia to mild skin infections. We hypothesized that evolutionary diversity may exist among USA300 clones, which may link virulence traits with host responses and mortality rates. METHODS: USA300 isolates from severe pneumonia (IP) and skin infection (IS) were characterized by pulsed-field gel electrophoresis (PFGE) and next-generation sequencing. Their virulence traits and host responses were compared in a lung infection model. RESULTS: The two USA300 isolates were found to be identical in genomic analysis. Robust IL-6 production, aggregation of bacteria, and hemorrhaging were observed in IP-infected lungs, which were associated with a higher rate of mortality than that observed with strain IS. Few neutrophils were detected in the lungs infected with strain IP, even at high bacterial loads. Massive production of α-toxin and coagulase were evident during the early phase of IP infection, and robust gene expression of hla (α-toxin) and lukS-PV (Panton-Valentine leukocidin), but not coa, agrA, or rnaIII, was confirmed in vitro. Strain IP also induced strong hemolysis in red blood cells. CONCLUSIONS: The present data demonstrated latent diversity in the virulence of USA300 clones. Unknown regulatory mechanisms, probably involving a host factor(s) as a trigger, may govern the virulence expression and resultant high mortality in certain sub-clones of USA300.

Molecular epidemiology of coagulase-negative bloodstream isolates: detection of Staphylococcus epidermidis ST2, ST7 and linezolid-resistant ST23

Abstract The mechanisms contributing to persistence of coagulase-negative staphylococci are diverse; to better understanding of their dynamics, the characterization of nosocomial isolates is needed. Our aim was to characterize phenotypic and molecular characteristics of Staphylococcus epidermidis and Staphylococcus haemolyticus human blood isolates from two tertiary care hospitals in Mexico, the Hospital Universitario in Monterrey and the Hospital Civil in Guadalajara. Antimicrobial susceptibility was determined. Biofilm formation was assessed by crystal violet staining. Detection of the ica operon and Staphylococcal Cassette Chromosome mec typing were performed by PCR. Clonal relatedness was determined by Pulsed-fiel gel electrophoresis and Multi locus sequence typing. Methicillin-resistance was 85.5% and 93.2% for S. epidermidis and S. haemolyticus, respectively. Both species showed resistance >70% to norfloxacin, clindamycin, levofloxacin, trimethoprim/sulfamethoxazole, and erythromycin. Three S. epidermidis and two S. haemolyticus isolates were linezolid-resistant (one isolate of each species was cfr+). Most isolates of both species were strong biofilm producers (92.8% of S. epidermidis and 72.9% of S. haemolyticus). The ica operon was amplified in 36 (43.4%) S. epidermidis isolates. SCCmec type IV was found in 47.2% of the S. epidermidis isolates and SCCmec type V in 14.5% of S. haemolyticus isolates. No clonal relatedness was found in either species. Resistance to clindamycin, levofloxacin, erythromycin, oxacillin, and cefoxitin was associated with biofilm production for both species (p < 0.05). A G2576T mutation in 23S rRNA gene was detected in an S. haemolyticus linezolid-resistant isolate. All linezolid-resistant S. epidermidis isolates belonged to ST23; isolate with SCCmec type IV belonged to ST7, and isolate with SCCmec type III belonged to ST2. This is the first report of ST7 in Mexico. There was a high genetic diversity in both species, though both species shared characteristics that may contibute to virulence.

Molecular epidemiology of coagulase-negative bloodstream isolates: detection of Staphylococcus epidermidis ST2, ST7 and linezolid-resistant ST23.

The mechanisms contributing to persistence of coagulase-negative staphylococci are diverse; to better understanding of their dynamics, the characterization of nosocomial isolates is needed. Our aim was to characterize phenotypic and molecular characteristics of Staphylococcus epidermidis and Staphylococcus haemolyticus human blood isolates from two tertiary care hospitals in Mexico, the Hospital Universitario in Monterrey and the Hospital Civil in Guadalajara. Antimicrobial susceptibility was determined. Biofilm formation was assessed by crystal violet staining. Detection of the ica operon and Staphylococcal Cassette Chromosome mec typing were performed by PCR. Clonal relatedness was determined by Pulsed-fiel gel electrophoresis and Multi locus sequence typing. Methicillin-resistance was 85.5% and 93.2% for S. epidermidis and S. haemolyticus, respectively. Both species showed resistance >70% to norfloxacin, clindamycin, levofloxacin, trimethoprim/sulfamethoxazole, and erythromycin. Three S. epidermidis and two S. haemolyticus isolates were linezolid-resistant (one isolate of each species was cfr+). Most isolates of both species were strong biofilm producers (92.8% of S. epidermidis and 72.9% of S. haemolyticus). The ica operon was amplified in 36 (43.4%) S. epidermidis isolates. SCCmec type IV was found in 47.2% of the S. epidermidis isolates and SCCmec type V in 14.5% of S. haemolyticus isolates. No clonal relatedness was found in either species. Resistance to clindamycin, levofloxacin, erythromycin, oxacillin, and cefoxitin was associated with biofilm production for both species (p<0.05). A G2576T mutation in 23S rRNA gene was detected in an S. haemolyticus linezolid-resistant isolate. All linezolid-resistant S. epidermidis isolates belonged to ST23; isolate with SCCmec type IV belonged to ST7, and isolate with SCCmec type III belonged to ST2. This is the first report of ST7 in Mexico. There was a high genetic diversity in both species, though both species shared characteristics that may contibute to virulence.

Frequent nasopharyngeal suctioning as a risk factor associated with neonatal coagulase-negative staphylococcal colonisation and sepsis.

INTRODUCTION: This case-control study aimed to determine whether catheter use was significantly associated with coagulase-negative staphylococci (CoNS) colonisation and/or sepsis in neonates. METHODS: Weekly swabs of the nose, umbilicus, rectum, wounds, eye discharge and intravenous catheter tips (after removal) of infants admitted to the neonatal intensive care unit of Universiti Kebangsaan Malaysia Medical Centre, Malaysia, were cultured. CoNS sepsis was diagnosed if pure growth of CoNS was cultured from the peripheral blood specimen of symptomatic infants. For each infant with CoNS colonisation or sepsis, a control infant was retrospectively and randomly selected from unaffected infants in the ward. Multivariate analyses were performed to determine whether catheter use was a significant risk factor. RESULTS: CoNS colonisation was detected in 113 (8.7%) infants. CoNS sepsis was found in 12 (10.6%) infants with CoNS colonisation and 7 (0.6%) infants without CoNS colonisation. Multivariate analysis showed that the following were significantly associated with CoNS colonisation: conjunctivitis (adjusted odds ratio [OR] 8.2, 95% confidence interval [CI] 1.9­34.8, p = 0.005); central venous catheters (adjusted OR 5.8, 95% CI 1.9­17.8, p = 0.002); and nasopharyngeal and/or oral suctioning more than twice in the 48 hours before positive culture (adjusted OR 7.3, 95% CI 3.3­16.2, p < 0.001). Exposure to frequent nasopharyngeal and/or oral suctioning (adjusted OR 20.8, 95% CI 3.5­125.3, p = 0.001) was the only significant factor associated with CoNS sepsis. CONCLUSION: Infants requiring more than two nasopharyngeal and/or oral suctions in the previous 48 hours were found to have a higher risk of developing CoNS colonisation and sepsis.

Multiple ligands of von Willebrand factor-binding protein (vWbp) promote Staphylococcus aureus clot formation in human plasma.

Staphylococcus aureus secretes coagulase (Coa) and von Willebrand factor-binding protein (vWbp) to activate host prothrombin and form fibrin cables, thereby promoting the establishment of infectious lesions. The D1-D2 domains of Coa and vWbp associate with, and non-proteolytically activate prothrombin. Moreover, Coa encompasses C-terminal tandem repeats for binding to fibrinogen, whereas vWbp has been reported to associate with von Willebrand factor and fibrinogen. Here we used affinity chromatography with non-catalytic Coa and vWbp to identify the ligands for these virulence factors in human plasma. vWbp bound to prothrombin, fibrinogen, fibronectin, and factor XIII, whereas Coa co-purified with prothrombin and fibrinogen. vWbp association with fibrinogen and factor XIII, but not fibronectin, required prothrombin and triggered the non-proteolytic activation of FXIII in vitro. Staphylococcus aureus coagulation of human plasma was associated with the recruitment of prothrombin, FXIII, and fibronectin as well as the formation of cross-linked fibrin. FXIII activity in staphylococcal clots could be attributed to thrombin-dependent proteolytic activation as well as vWbp-mediated non-proteolytic activation of FXIII zymogen.

Relação entre a resistência a oxacilina e a produção de biofilme de amostras de origem comunitária e hospitalar pertencentes a diferentes espécies de Staphylococcus coagulase negativo / Relationship between resistance to oxacillin and biofilm production samples of Community and hospital belonging to different species of coagulase-negative Staphylococcus

Nas últimas décadas, os Staphylococcus coagulase-negativo, têm sido considerados como patógenos verdadeiros, sendo um dos principais grupos bacterianos responsáveis pelas infecções relacionadas a assistência a saúde (IRAS). O presente estudo teve como objetivo geral: avaliação da relação entre a resistência a oxacilina e a produção de biofilme de amostras Staphylococcus coagulase-negativo de origem comunitária e hospitalar. Neste sentido, foram desenvolvidos os seguintes objetivos específico: identificar ao nível de espécie os Staphylococcus coagulase-negativo; analisar por técnica fenotípica (Ágar vermelho do Congo) a produção de slime; avaliar quantitativamente, a produção de biofilme; correlacionar a produção de polissacarídeos extracelulares (slime) com a produção de biofilme; avaliar a relação da resistência a oxacilina como indicador da presença do gene mecA; avaliar a relação entre a concentração inibitória mínima e a concentração bactericida mínima para oxacilina; pesquisar a presença dos genes mecA, icaAD e atlE, pela técnica de PCR. Foi estudado um total de 150 amostras, sendo 50 isoladas de fômites, 50 isoladas de sangue e 50 isoladas de comunidade. Independente da origem, foram identificadas 14 espécies de Staphylococcus coagulase-negativo, sendo mais frequentes S. epidermidis 42,6%, S. haemolyticus 13,3% e S. cohnii cohnii 10,7%. A análise geral da expressão fenotípica de slime mostrou que 64% das amostras avaliadas eram produtoras de slime. Das 150 amostras testadas neste estudo, 95,3% foram produtoras de biofilme. Ao considerarmos a análise da quantificação do biofilme em relação às origens das amostras estudadas não encontramos diferenças significativas e a maioria das amostras foi considerada moderadamente produtora de biofilme. O gene mecA foi detectado em 6 amostras comunitárias, 34 amostras de fômites e 34 amostras de sangue. Não houve diferença significativa entre as amostras de fômites e sangue...

In recent decades, coagulase-negative Stapphylococci have been considered as true pathogen, one of the major bacterial groups responsible for hospital infection. The present study aimed to: assess the relationship between oxacillin resistance and biofilm production samples coagulase-negative Stapphylococci of community and hospital. In this sense, we have developed the following specific objectives: to identify to species level coagulase-negative Staphylococci; analyze by phenotypic test (Congo red Agar) slime production, evaluate quantitatively the biofilm production; correlate the production of extracellular polysaccharides (slime) with biofilm production; evaluate the relationship of resistance to oxacillin as an indicator of the presence of the mecA gene; evaluate the relationship between minimal inhibitory concentration and minimum bactericidal concentration for oxacillin; investigate the presence of the mecA gene, atlE and icaAD, by PCR. We studied a total of 150 samples, 50 were isolated from fomites, 50 from community and 50 isolated from blood. Regardless of origin, 14 species of coagulase-negative Stapphylococci were identified , being more frequent 42.6% S.epidermidis, 13.3% S. haemolyticus and 10.7% S. cohnii cohnii. A general analysis of the phenotypic expression of slime showed that 64% of the samples were slime producers...

Shortening the antibiotic course for the treatment of neonatal coagulase-negative staphylococcal sepsis: fine with three days?

BACKGROUND: The incidence of coagulase-negative staphylococcal (CoNS) sepsis is high in neonatal intensive care units (NICUs) and treatment significantly adds to the antibiotic pressure, increasing the threat of resistance. Because infants recover within 24-48 h, blood cultures are negative within 48 h and CRP normalizes within 72 h, we reduced anti-CoNS treatment from 7 to 3 days in infants with uncomplicated CoNS sepsis. OBJECTIVES: The aim of the study was to evaluate the effect of short (3 days) treatment duration for CoNS sepsis. METHODS: All infants with CoNS sepsis from January 2006 to September 2010 were evaluated. Before 2008 the duration of anti-CoNS treatment was 7 days, but in 2008 it was reduced to 3 days, provided that infants recovered within 48 h, CRP value decreased, thrombocytes were normal and central venous catheters were either not present or removed. Clinical results of treatment for 3 days were compared with 7 days of treatment. RESULTS: There were 142 infants with CoNS sepsis who were eligible for 3 days of antimicrobial treatment duration, 62 (44%) from the period 2006-2008 were treated over 7 days (Group 1) and 80 (56%) from the period 2008-2010 were treated over 3 days (Group 2). Clinical characteristics were not different between the groups. All infants recovered within 48 h and CoNS sepsis did not relapse. CONCLUSIONS: Antibiotic treatment for CoNS sepsis may be shortened to 3 days when clinical improvement is rapid and central lines are not present. Prospective randomized studies are needed to confirm the results of this single-center study. Future studies may reveal the effects on the development of antimicrobial resistance.

Epidemiology and significance of coagulase-negative staphylococci isolated in blood cultures from critically ill adult patients.

BACKGROUND: Little published data are available on the epidemiology and significance of coagulase-negative staphylococci (CoNS) in blood culture isolates among critically ill adult patients. OBJECTIVES: To describe the epidemiology and frequency of CoNS blood culture isolates in critically ill adults, and investigate the association between time to positivity (TTP) of blood cultures and number of culture-positive bottles with organ dysfunction and mortality. DESIGN, SETTING AND PARTICIPANTS: A retrospective chart audit in the intensive care unit of a tertiary hospital comprising all patients who had positive blood cultures for CoNS in 2009. MAIN OUTCOME MEASURES: TTP, number of culture-positive bottles, Sequential Organ Failure Assessment (SOFA) scores, resolution of fever and white cell response and inotrope requirement, length of stay in ICU and mortality. RESULTS: In 2009, there were 1514 and 109 positive blood culture sets for the hospital and ICU patients, respectively. Of these, 515 sets from patients outside the ICU (34% of all hospital positive blood cultures) and 54 from the ICU (49.5% of all ICU positive blood cultures) were positive for CoNS. Patients with TTP ≤24 hours had higher organ failure scores by 0.9 (95% CI, 0-3.4; P = 0.052). There was a trend towards an association between increased 28-day mortality and TTP ≤24 hours (7/22 v 3/32; P = 0.071). There was no significant correlation between number of bottles positive for culture and mortality, length of stay, SOFA score, resolution of fever, white cell response, and inotrope requirement. CONCLUSIONS: Early TTP of blood cultures with CoNS may be associated with poorer outcome and may be a marker of true infection. Given the relatively high frequency of this microbiological problem, larger prospective observational studies are required to more clearly define the significance of a CoNS blood culture isolates in critically ill adult patients.

Comparison of dog and rabbit plasmas in the tube coagulase test for Staphylococcus aureus.

The tube coagulase test, an invaluable laboratory tool for identifying Staphylococcus aureus, is most often done using rabbit plasma. However, there is evidence that depending on the origin of the isolates, other plasmas may be superior. The current study sought to compare the utility of dog and rabbit plasma in the coagulase test for S. aureus isolated from canine (n = 28), bovine (n = 29), and human (n = 30) hosts. Overall, coagulation times were significantly faster for dog (2.38 hr) than rabbit (3.19 hr) plasma. When coagulation times were compared by isolate origin, no significant differences were found for rabbit plasma, whereas bovine isolates clotted dog plasma significantly faster (1.86 hr) than canine (2.79 hr) or human (2.38 hr) isolates. Investigators should be aware that rabbit plasma may not be the ideal coagulase-testing medium for S. aureus from all sources.

Neonate twin with staphylococcal scalded skin syndrome from a renal source.

OBJECTIVE: To understand the underlying mechanism of exfoliative toxins causing staphylococcal scalded skin syndrome or Ritter's Disease that predominantly affects newborns and infants, although it is sometimes found in adults. Staphylococcal scalded skin syndrome is typically diagnosed by the characteristic fluid-filled bullae together with superficial skin loss. A histopathological diagnosis may be made by looking for subcorneal acantholytic cleavage with minimal inflammation on biopsy, although this is not normally required. Exfoliative toxin A and B are both responsible for the "acantholytic" infection of Staphylococcus aureus as they target desmoglein-1 leading to loss of cell-to-cell cohesion and subsequent spread of infection. Other factors produced by S. aureus can cause a myriad of other problems including neutralization of antimicrobial peptides, inactivation of neutrophils, proteolysis, T-cell anergy, and immunosuppression. DESIGN: Individual care report. SETTING: Pediatric intensive care unit. PATIENT: We describe a normal male infant who was born at term and developed 100% total body surface area staphylococcal scalded skin syndrome on the 14 day of life with associated renal sepsis. INTERVENTIONS: After cultures from the lesions, bloodstream, and urine were obtained, intravenous Vancomycin and Ceftriaxone were commenced. The initial lesions increased in size over a 36-hr period to cover the entire body surface; this was associated with a decline in hemodynamic status. MEASUREMENTS AND MAIN RESULTS: Cultures from the urine and blood grew coagulase-positive S. aureus. An ultrasound scan revealed bilateral pyonephroses, which necessitated the placement of percutaneous nephrostomies with subsequent decompression of the collecting system. CONCLUSIONS: After the decompression hemodynamic status stabilized and over the ensuing 10 days, the patient made a full recovery with no scarring. No similar lesions were noticed on the infant's twin brother. We discuss the recent developments in understanding the underlying mechanism of exfoliative toxins causing staphylococcal scalded skin syndrome, review current treatment guidelines, and outline the need for new therapeutic options.

The pitfall of coagulase-negative staphylococci: a case of Staphylococcus lugdunensis endocarditis.

We report a case of a 60-year-old woman. She was transferred from a local hospital to our cardiovascular medicine department with a diagnosis of infectious endocarditis due to Staphylococcus lugdunensis. Transthoracic echocardiograph confirmed the presence of large vegetations on the native aortic and mitral valve, and subsequent severe regurgitation due to the aortic and mitral valve destruction. Emergent operation was performed and patient's life was barely rescued. However, S. lugdunensis belongs to coagulase-negative staphylococci, which are generally regarded as relatively avirulent bacterium, the endocarditis caused by S. lugdunensis can be invasive and often resembles endocarditis due to Staphylococcus aureus. Therefore, whenever this organism is found in patients with endocarditis, early surgical treatment of the infected valve should be considered.

Pharmacoeconomic analysis of microbiologic techniques for differentiating staphylococci directly from blood culture bottles.

Differentiating staphylococci in blood cultures is a critical issue, particularly when only one of two cultures is positive by Gram staining for staphylococci. New tests for the identification of Staphylococcus aureus allow faster results and definitive treatment compared to the tube coagulase test interpreted at 24 h (TCT24). These newer tests, peptide nucleic acid fluorescence in situ hybridization (PNA-FISH) and real-time PCR (RT-PCR), offer improved sensitivity at higher cost. Data suggest that the tube coagulase test may be interpreted at 4 h (TCT4) with little loss of sensitivity. The impact of variability in turnaround time, sensitivity, specificity, and cost on comparative cost-effectiveness is unknown. Our aim was to establish the cost-effectiveness of TCT24, PNA-FISH, RT-PCR, and TCT4 for direct identification of staphylococci in blood cultures. Decision analysis comparing these strategies was done from the institutional perspective. Besides test variables, other variables included patient risk factors, empirical treatment, and follow-up cultures. Probability and cost estimates came from the literature and institutional data. Base case estimates were derived from institutional rates of 73% contamination when coagulase-negative staphylococci were identified, 67.6% prevalence of risk factors, and 12.4% prevalence of S. aureus when one of two cultures yielded staphylococci. Sensitivity analysis was done across a range of probabilities and costs. In the base case, TCT4 and TCT24 were more cost-effective than RT-PCR and PNA-FISH ($78 versus $120 versus $165 per patient, respectively). The advantage of TCT4 and TCT24 remained robust upon sensitivity analysis. TCT4 should be further evaluated as a rapid, cost-effective means for identification of S. aureus in blood cultures.

Persistent strains of coagulase-negative staphylococci in a neonatal intensive care unit: virulence factors and invasiveness.

Coagulase-negative staphylococci (CoNS) are the major cause of nosocomial bacteraemia in neonates. The aim of this study was to investigate whether persistent strains of CoNS possess specific bacterial characteristics as compared with sporadic non-cluster isolates. In total, 180 blood culture isolates (95 contaminants and 85 invasive isolates) obtained from a single neonatal unit over a 12-year period were studied. Pulsed-field gel electrophoresis (PFGE) identified 87 persistent CoNS strains (endemic clones). The two largest PFGE clusters belonged to a single clonal complex according to multilocus sequence typing. Patients colonised or infected with endemic clones were of lower gestational age than those infected with non-cluster strains. One Staphylococcus haemolyticus cluster appeared to selectively colonise and infect the most extreme pre-term infants. Endemic clones were characterised by high levels of antibiotic resistance and biofilm formation. All 51 isolates belonging to the two largest PFGE clusters were ica operon-positive. Genes encoding Staphylococcus epidermidis surface protein B and the production of phenol-soluble modulins (PSMs) were also more prevalent among endemic clones than among non-cluster strains. However, endemic clones were not more prevalent among invasive isolates than among contaminants. These findings indicate that multiple selective factors, including antibiotic resistance, biofilm formation, surface proteins with adhesive properties, and PSMs regulated by agr, increase the ability of CoNS to persist in a hospital environment. It may be more prudent, when searching for new therapeutic targets, to focus on ubiquitous components of CoNS instead of putative virulence factors that do not clearly contribute to increased invasive capacity.

Substantial myocardial abscess in an immunocompromised patient: fatal outcome after coagulase-negative Staphylococcal native valve infection.

We present the fatal case of a patient with a 3-month history of malaise, fatigue, low-grade fever and increasing signs of heart failure. Because of a sudden loss of sight and elevated sedimentation rate, arteritis temporalis was mistakenly suspected and treatment with high dose prednisolone was initiated. Five weeks later the patient presented with worsening of symptoms and septicemia with coagulase negative staphylococcus (CoNS). Transesophageal echocardiography revealed a left atrial mass and stenosis of a severely calcified aortic valve, but no definite vegetations. The diagnose of infectious endocarditis was established during surgery, with the discovery of an abscess cavity at the non-coronary cusp of the aortic valve and by the growth of the same CoNS from tissue samples from the abscess in the atrial wall, as had been found in blood cultures. A systolic murmur was heard initially, but echocardiography was not performed until 5 weeks later and illustrates the pivotal role of echocardiography in the early diagnosis and treatment of infectious endocarditis.

The neutralizing effects of hyperimmune antibodies against extracellular fibrinogen-binding protein, Efb, from Staphylococcus aureus.

Staphylococcus aureus is a significant cause of acute and chronic infection and boasts a diverse array of virulence factors. S. aureus produces and secretes a protein, extracellular fibrinogen (Fg)-binding protein (Efb), which contributes to virulence in wound infection. Efb binds to both Fg and platelets and inhibits platelet function in vitro and in vivo. In this study, we have characterized the antibody response against Efb. Antibodies generated in response to immunization with Efb can neutralize the biological effects of Efb. Hyperimmune sheep immunoglobulin (Ig)G against Efb blocked the binding of Efb to Fg and prevented Efb-mediated inhibition of platelet aggregation. Furthermore, these antibodies cross-reacted with coagulase and blocked coagulase activity in plasma. Immunization of mice with Efb resulted in the generation of high titre specific antibodies. When subjected to a foreign-body-associated wound infection, the vaccinated animals developed significantly less severe wound infection than the unvaccinated controls. Also, human IgG against Efb was prepared from commercial IgG pools; however, the monospecific human anti-Efb that was enriched was unable to neutralize Efb. We conclude that immunization with Efb is required in order to generate a protective antibody response to Efb from S. aureus.

Coagulase-negative staphylococcal sepsis as a predictor of bronchopulmonary dysplasia.

AIM: To determine whether sepsis caused by coagulase-negative staphylococci (CoNS) is a risk factor for developing bronchopulmonary dysplasia (BPD) in premature newborns. METHODS: All newborns born at < or = 30 wk of gestation at Orebro University Hospital during 1994-2001 with clinical sepsis caused by CoNS (group A, n = 22) or by other bacteria (group B, n = 17) were included and compared with premature newborns without sepsis (group C, n = 53). Clinical sepsis was defined as a positive blood culture (monoculture) plus clinical symptoms and laboratory findings. BPD was defined as treatment with oxygen > 21% for at least 28 d. RESULTS: The incidence of BPD differed between the three groups, as follows: CoNS sepsis (A) 64%, other sepsis (B) 41% and control (C) 24%. The difference between the control group and the sepsis groups was highly significant (p = 0.006). In a univariate model the crude estimates of relative risk (RR) for occurrence of BPD increased with presence of sepsis and particularly with presence of sepsis with CoNS (A: RR 2.6, 95% CI 1.5-4.6, p = 0.001; B: RR 1.7, CI 0.8-3.5, p = 0.17). When regression was performed with two additional predictive variables in multivariate models including sepsis, gestational age and mechanical ventilation (group A: RR 1.5, CI 1.1-2.0, p = 0.004; group B: RR 0.9, CI 0.6-1.4, p = 0.67), the estimates were lower. CONCLUSION: The relative risk for BPD is significantly increased in premature newborns with sepsis caused by CoNS compared with those with sepsis caused by other bacteria and compared with premature newborns with no sepsis.

Expression of plasma coagulase among pathogenic Candida species.

Candida coagulase production was assessed by the classical tube test. All Candida krusei strains were coagulase negative, but most C. albicans and C. tropicalis strains can produce coagulase. Some strains agglutinated the Pastorex Staph-Plus reagent, probably because of antigen similarities to coagulase produced by Staphylococcus aureus that may cause mistakes in clinical laboratories.