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Effect of iron limitation on slime production by Staphylococcus aureus.

The aim of this study was to examine the effect of growth conditions on slime production by Staphylococcus aureus clinical isolates. The addition of glucose to the medium enhanced slime production in the majority of Staphylococcus aureus isolates cultured from infections associated with orthopaedic prostheses. Iron limitation also stimulated this ability even in the absence of the additional carbohydrate source. Staphylococcus aureus isolates were classified as Group 1 [strains producing slime only in trypticase soy broth supplemented with 1% glucose (TSBG) or in iron-limited trypticase soy broth (TSB/Fe-)]; Group 2 (slime + only in TSB/Fe-); or Group 3 (slime+ only in TSBG). Seven repeatedly slime-negative strains were stimulated to produce slime by subpassaging in iron-limited medium. Low iron levels, usually found in vivo, could stimulate slime production by Staphylococcus aureus and support chronic infections associated with orthopaedic prostheses.

Bacterial Proteins↗

Survey of staphylococcal enterotoxin genes, exfoliative toxin genes, and toxic shock syndrome toxin 1 gene in non-Staphylococcus aureus species.

The aim of this study was to analyze the presence of staphylococcal exotoxin genes in staphylococci other than Staphylococcus aureus. Whereas for Staphylococcus aureus a large spectrum of different exotoxins responsible for toxin-mediated diseases has been described, only few and conflicting data are available regarding toxin production in all other staphylococcal species. A collection of clinical non-Staphylococcus aureus staphylococcal isolates were systematically screened for the presence of genes for toxic shock syndrome toxin 1, exfoliative toxins, and classical enterotoxins by using multiplex polymerase chain reaction enzyme immunoassays. In a total of 461 isolates of 18 different (sub)species derived from clinical specimens, no toxin gene sequences were amplified. The results indicate that the occurrence of toxin genes involved in staphylococcal toxin-mediated diseases is at least very rare in human-derived isolates of non-Staphylococcus aureus species.

Bacterial Toxins↗

Life-threatening hemoptysis in adults with community-acquired pneumonia due to Panton-Valentine leukocidin-secreting Staphylococcus aureus.

Three new consecutive cases of life-threatening hemoptysis in adults with community-acquired pneumonia due to Panton-Valentine leukocidin-secreting Staphylococcus aureus are presented, focusing on the particular clinical presentation of this new entity. Between December 1999 and March 2001, three adults aged from 23 to 67 years were admitted to our respiratory intensive care unit for massive hemoptysis and septic shock associated with community-acquired Staphylococcus aureus pneumonia. Isolates were sent to the Centre National de Référence des Toxémies Staphylococciques in Lyon, France, where they were found to secrete Panton-Valentive leukocidin. The clinical course was similar in the three patients, with massive hemoptysis and septic shock necessitating mechanical ventilation. Two patients died rapidly; necropsy showed pulmonary vascular necrosis in one of them. The third patient recovered after appropriate antibiotic therapy. Leukocidin/neutrophil interactions in the pulmonary vasculature may cause severe hemoptysis in patients with community-acquired Staphylococcus aureus pneumonia secreting Panton-Valentine leukocidin. Adult patients with massive hemoptysis and suspected community-acquired pneumonia should receive antibiotic regimens covering Staphylococcus aureus.

Adult↗

Bacteremic pneumococcal cellulitis compared with bacteremic cellulitis caused by Staphylococcus aureus and Streptococcus pyogenes.

In order to better characterize bacteremic cellulitis caused by Streptococcus pneumoniae, a review was conducted of 10 cases of bacteremic pneumococcal cellulitis, which represented 0.9% of all cases of pneumococcal bacteremia (n=1,076) and 3.2% of all cases of community-acquired bacteremic cellulitis (n=312) that occurred in the Hospital de Bellvitge, Barcelona, from 1984 to 2001. In addition to these 10 cases, 28 cases of bacteremic pneumococcal cellulitis from the literature (Medline 1975-2001) were reviewed. Pneumococcal cellulitis of the face, neck, and trunk was observed more frequently in patients with systemic lupus erythematosus and hematologic disorders, while pneumococcal cellulitis of the limbs was more common in patients with diabetes, alcoholism, and parenteral drug use. In the Hospital de Bellvitge group, bacteremic cellulitis due to Streptococcus pneumoniae was more frequently associated with severe underlying diseases than that due to Staphylococcus aureus or Streptococcus pyogenes (100%, 57%, and 72%, respectively;P=0.01). A concomitant extracutaneous focus of infection (e.g., respiratory tract infection) suggesting hematogenous spread with metastatic cellulitis was more frequent in patients with pneumococcal cellulitis, while a local cutaneous entry of microorganisms was feasible in most patients with Staphylococcus aureus or Streptococcus pyogenes cellulitis. The 30-day mortality was 10% in patients with pneumococcal cellulitis, 13% in patients with Staphylococcus aureus cellulitis, and 23% in patients with Streptococcus pyogenes cellulitis (P=0.3). Thus, bacteremic pneumococcal cellulitis is an unusual manifestation of pneumococcal disease and occurs mainly in patients with severe underlying diseases. In most cases, pneumococcal cellulitis has a different pathophysiologic mechanism than cellulitis caused by Staphylococcus aureus or Streptococcus pyogenes.

Adult↗

Management of catheter-related Staphylococcus aureus bacteremia: when may sonographic study be unnecessary?

This study reviews the outcome of patients with uncomplicated catheter-related Staphylococcus aureus bacteremia diagnosed in our hospital from January 1997 to December 1999 and treated with short-course antibiotic therapy. Our aim was to assess the effectiveness of this regimen for minimizing complications (relapses, endocarditis and metastatic foci). A total of 213 episodes of bacteremia were registered and 167 (78.4%) were nosocomial. Among these, 87 (52.1%) were catheter-related Staphylococcus aureus bacteremia and 20 were primary nosocomial bacteremia. Endocarditis was diagnosed during the acute episode in 7/107 of these patients (2 by persistent fever after catheter removal and 5 by metastatic foci; 3 of them also had cardiac risk factors) and confirmed with transesophageal echocardiography. Among the 84/87 catheter-related Staphylococcus aureus bacteremia and 16/20 primary nosocomial bacteremia patients who did not develop endocarditis, 31 patients died during the acute episode (16 due to sepsis despite initiation of antibiotic treatment and 15 due to the underlying disease) and five had osteoarticular foci. The remaining 64 episodes were considered to be uncomplicated bacteremia (no cardiac risk factors, persistent fever, metastatic foci, or clinical signs of endocarditis) and were treated with 10-14 days of high-dose antistaphylococcal antibiotics. Echocardiography was not mandatory in these patients. Of the 64 uncomplicated episodes, 62 were followed for at least 3 months and none relapsed or developed endocarditis. Even though some of the patients might have had subclinical endocarditis, short-course therapy with high doses of antistaphylococcal antibiotics was effective for treating uncomplicated catheter-related Staphylococcus aureus bacteremia. Transesophageal echocardiography may not be necessary in these cases.

Anti-Bacterial Agents↗

Staphylococcus aureus carriage among participants at the 13th European Congress of Clinical Microbiology and Infectious Diseases.

The aim of this study was to measure the rate of Staphylococcus aureus nasal colonization among attendees of the 13th European Congress of Clinical Microbiology and Infectious Diseases (ECCMID), particularly with regard to methicillin-resistant (MRSA) strains. The 31.4% rate of Staphylococcus aureus colonization detected among the participants was in line with colonization rates reported previously for healthcare workers. A statistical difference was found between the rates of Staphylococcus aureus carriage in physicians (37.4%) and non-physicians (21.7%) but not between males (35.0%) and females (28.9%). Only one participant (a Belgian physician) was found to carry MRSA. Surprisingly, the rate of methicillin-susceptible Staphylococcus aureus carriage was significantly higher among participants from countries with a low prevalence of MRSA.

Carrier State↗

Comparison of genotypes of methicillin-resistant and methicillin-sensitive Staphylococcus aureus in Finland.

The frequency of horizontal transfer of the staphylococcal cassette chromosome mec to methicillin-susceptible Staphylococcus aureus is unknown. In order to gain more information regarding this frequency in Finland, the genotypes of 299 clinical methicillin-sensitive Staphylococcus aureus isolates were compared to representatives of 24 epidemic methicillin-resistant Staphylococcus aureus genotypes. Sixty-eight percent of the methicillin-sensitive isolates had a genotype similar to eight of the epidemic methicillin-resistant strains. The remaining isolates (32%) showed 22 different genotypes. The results indicate that, in Finland, several methicillin-sensitive Staphylococcus aureus genotypes may have acquired the staphylococcal cassette chromosome mec.

Finland↗

In vitro zones of inhibition of coated vascular catheters predict efficacy in preventing catheter infection with Staphylococcus aureus in vivo.

This report summarizes data from 35 rabbit model experiments investigating the relationship between in vitro anti-infective catheter coating zones of inhibition and in vivo efficacy. The rabbit model studies involving 15 anti-infective coatings demonstrate an inverse correlation between the sizes of zones of inhibition of Staphylococcus aureus and both the quantity of Staphylococcus aureus removed from the catheter and the risk of a purulent infection. The review of seven previously published clinical trials reveals that the use of anti-infective coated catheters, efficacious in the rabbit model, was associated with a higher success rate than the use of uncoated catheters in preventing both Staphylococcus aureus catheter colonization (odds ratio: 1.28; 95% confidence interval: 0.84-1.93) and Staphylococcus aureus catheter-related bloodstream infection (odds ratio: 3.07; 95% confidence interval: 0.98-9.60) in humans. These findings strongly suggest a correlation between zones of inhibition and in vivo efficacy. In vitro zones of inhibition may serve as a useful screening test for evaluating new anti-infective coatings.

Animals↗

Molecular characterization and transfer among Staphylococcus strains of a plasmid conferring high-level resistance to mupirocin.

In this work, mupirocin resistance was correlated with the presence of plasmids in methicillin-resistant Staphylococcus aureus (MRSA) strains isolated in the Rio de Janeiro Federal University Hospital in Brazil, where topical mupirocin has been used extensively since 1990. Of 19 strains studied, those exhibiting high-level resistance carried a large and relaxable plasmid of about 35 kb. Mupirocin-sensitive derivatives, obtained by growth at 42 C of a strain exhibiting high-level resistance, were devoid of the large plasmid, which was designated pMG1. Mupirocin resistance was transferred to strain RN8411 during overnight filter-matings at low frequencies (7.0 x 10(-9)/donor). The pMG1 plasmid was shown to be responsible for high-level mupirocin resistance in our isolates and to be incompatible with pGO1. Hybridization experiments suggested that mupirocin resistance in pMG1 is due to the presence of the ileS-2 gene. The pMG1 plasmid was successfully and bidirectionally transferred from Staphylococcus aureus to Staphylococcus epidermidis, suggesting that the latter may be a reservoir of this resistance plasmid. No transfer was detected to Staphylococcus haemolyticus. The development of self-transferable high-level mupirocin resistance should be considered when using mupirocin to control the spread of MRSA in hospitals.

Anti-Bacterial Agents↗

Staphylococcus aureus adherence to nasal epithelial cells in a physiological in vitro model.

Nasal carriage of Staphylococcus aureus represents a risk factor for subsequent invasive infections and interpatient transmission of strains. No physiological in vitro model of nasal epithelial cells is available to study both patient- and bacteria-related characteristics and their interaction, leading to adherence and colonization. Starting with tissues from human nasal polyps, a confluent, squamous, nonkeratinized epithelium in collagen-coated 96-well microtiter plates was obtained after 14 d. This in vitro cell-layer was characterized histologically, ultrastructurally, and immunohistochemically and showed features that were indistinguishable from those observed in the squamous nonkeratinized epithelium found in the posterior part of the vestibulum nasi. Adherence experiments were performed with four different 3H-thymidine-labeled Staphylococcus aureus strains. The effect of bacterial inoculum size, temperature of incubation, and incubation medium were studied. The adherence results were found to be reproducible, reliable and sensitive, allowing detection of small quantitative differences in adherence between the Staphylococcus aureus strains. There was no significant difference in adherence at 23 degrees C and 37 degrees C, nor between the incubation medium M199 and phosphate-buffered saline. Plastic adherence could be reduced and standardized with use of siliconized tips and a constant bacterial inoculum volume of 100 microl/well. This physiological and reliable in vitro cell-culture model offers a unique opportunity to study Staphylococcus aureus adherence to squamous, nonkeratinized nasal epithelial cells and both patient and bacterial characteristics involved in this interaction.

Bacterial Adhesion↗

Successful treatment of Staphylococcus lugdunensis endocarditis complicated by multiple emboli: a case report and review of the literature.

We describe the prompt diagnosis and successful treatment of mitral valve endocarditis in a 52-year-old woman due to a recently described coagulase negative staphylococcus, Staphylococcus lugdunensis. Endocarditis due to this organism has a high mortality rate with 8 out of 12 published cases ending in fatality. Review of the literature revealed that use of commercial identification systems can lead to misidentification of Staphylococcus lugdunensis and consequently delay appropriate treatment. It is clinically important to distinguish Staphylococcus lugdunensis from other coagulase negative staphylococci by detailed microbiological testing. The awareness of this from of endocarditis and its natural history is important since it differs significantly from other coagulase negative staphylococci. It highlights the need for early surgical intervention not only for haemodynamic complications but also for recurrent emboli. Multiple emboli appears to be a frequent finding on review of the literature.

Anti-Bacterial Agents↗

Staphylococcus hominis endophthalmitis associated with a capsular hypopyon.

PURPOSE: To report a case of Staphylococcus hominis endophthalmitis associated with a capsular hypopyon. DESIGN: Interventional case report. METHODS: A 51-year-old man presented with chronic postcataract extraction inflammation and underwent vitrectomy, partial capsulectomy, and intravitreal antibiotic injections, followed by explantation of the intraocular lens and capsule. RESULTS: A capsular hypopyon in the absence of an anterior chamber hypopyon was noted. Cultures of the vitreous and capsule revealed Staphylococcus hominis, a coagulase-negative gram-positive organism. CONCLUSIONS: We are unaware of previous reports of endophthalmitis caused by Staphylococcus hominis, and could find none in a computerized search using MEDLINE. This case adds Staphylococcus hominis to the list of causative organisms in chronic endophthalmitis and illustrates the rare finding of a capsular hypopyon.

Amikacin↗

Biofilm formation by Staphylococcus aureus and Pseudomonas aeruginosa is associated with an unfavorable evolution after surgery for chronic sinusitis and nasal polyposis.

OBJECTIVES: To determine whether biofilm-forming capacity of bacteria demonstrated in chronic rhinosinusitis (CRS) has an impact on persistence of the disease following endoscopic sinus surgery (ESS). METHOD: Thirty-one bacterial strains recovered from 19 patients with CRS at least 1 year post-ESS. Evolution of disease was assessed by questionnaire and endoscopy as favorable or unfavorable. The bacteria were cultured on a 96-well culture plaque and a semi-quantitative method using crystal violet to quantify biofilm production was used. RESULTS: Twenty-two of 31 samples produced a biofilm thicker or equal to the positive control. Biofilm production was noted in 6/10 Pseudomonas aeruginosa isolates, 8/10 Staphylococcus aureus, and 8/11 coagulase-negative staphylococci. Biofilm formation was associated with a poor evolution for Pseudomonas aeruginosa and Staphylococcus aureus, but not coagulase-negative staphylococcus. CONCLUSION: There is a correlation between in vitro biofilm-producing capacity by Pseudomonas aeruginosa and Staphylococcus aureus and unfavorable evolution after ESS, suggesting a role for biofilm production in chronic sinusitis. EBM RATING: B-2b.

Adult↗

Epidemiosurveillance of antimicrobial compound resistance of Staphylococcus intermedium clinical isolates from canine pyodermas.

In a retrospective study, 131 Staphylococcus intermedius strains isolated from apparently healthy dogs, and 187 Staphylococcus intermedius strains isolated from dog pyodermas in the clinical microbiology laboratory at the National Veterinary School in Nantes, during three successive periods: 1986-87, 1992-93 and 1995-96, were investigated and compared for their antimicrobial susceptibility. Results indicated that 60% to 65% of the strains were susceptible to Chloramphenicol and Doxycyclin, 65% to 80% of the strains were susceptible to macrolides (Erythromycin, Lincomycin and Clindamycin) and to Trimethoprim/Sulfonamide association. More than 95% of the strains were susceptible to three betalactamins tested: Oxacillin, Amoxycillin/Clavulanic acid, Cephalexin, to Gentamicin, to Fucidic Acid and to two quinolones: Enrofloxacin and Marbofloxacin. This last group is made up of choice antibacterials for the treatment of dog pyoderma. Many different resistance patterns were observed in each period with no really predominant profile, because of low plasmidic vs chromosomal balance of the genetic basis of antibacterial resistance in Staphylococcus intermedius. However, the proportion of multiresistant (> or = 3 drugs) strains increased from 10.8% in the first period, to 28% in the third period. This increased frequency of resistance suggests strongly that, as in Staphylococcus aureus human infections, the prescription of antibiotic compounds increases the prevalence of resistant strains.

Aminoglycosides↗

Presence of glutamine at position 74 of pocket 4 in the BoLA-DR antigen binding groove is associated with occurrence of clinical mastitis caused by Staphylococcus species.

Potential relationships between amino acid motifs in the antigen binding groove of various alleles of the bovine major histocompatibility complex DR (BoLA-DR) molecule and occurrence of clinical mastitis caused by Staphylococcus species (non-Staphylococcus aureus) were investigated in a case-control study. A significant association (P< or =0.05) was detected between the presence of glutamic acid at position beta 74 and occurrence of mastitis caused by Staphylococcus spp. with a relative risk of 11. This motif is present in BoLA-DRB3.2*22, *23 and *24 alleles. Presence of a positively charged residue (arginine or lysine) at position 13 also showed a tendency (P< o r=0.1) towards an association with a higher risk of clinical mastitis caused by the same bacteria. This motif is present in BoLA-DRB3.2*23 and *8 alleles. Similarly, presence of arginine at position beta 71 (present in alleles *23 and *22) was associated with occurrence of this disease. These positions (beta 13, beta 71 and beta 74) form pocket 4 of the antigen binding groove, which plays an instrumental role in antigen binding and recognition by T-lymphocytes. Thus, it can be concluded that pocket 4 of the BoLA-DR molecule is involved in conferring susceptibility to clinical mastitis caused by Staphylococcus spp.

Alleles↗

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↗

"Staphylococcus pettenkoferi," a novel staphylococcal species isolated from clinical specimens.

In this report we describe a novel species of coagulase-negative novobiocin susceptible staphylococci obtained from an epidemiologically unrelated blood culture and a wound infection. These isolates significantly differed from all other validated Staphylococcus species based on phenotypic characteristics and 16S rRNA gene sequencing. Both isolates had identical 16S rRNA sequences and phylogenetic trees constructed from evolutionary distances showed that this species formed a distinct and deep subline that was most closely related to members of the Staphylococcus saprophyticus cluster group (S. kloosii, S. gallinarum, S. arlettae, S. saprophyticus, S. xylosus, S. equorum, S. succinus and S. cohnii) and Staphylococcus auricularis. Furthermore these strains could each be distinguished from all other staphylococci based on at least one phenotypic trait. Therefore we propose the designation of "Staphylococcus pettenkoferi" a novel species of coagulase-negative staphylococci.

Adult↗

Toll-like receptor 2 expression on human conjunctival epithelial cells: a pathway for Staphylococcus aureus involvement in chronic ocular proinflammatory responses.

BACKGROUND: Staphylococcus aureus colonization is common in atopic keratoconjunctivitis, potentially activating epithelial cells via toll-like receptor 2 (TLR-2) and the receptor for platelet-activating factor (PAFR). OBJECTIVES: To examine human conjunctival epithelial cells for the expression of TLR-2 in vitro and in vivo and to evaluate the role of TLR-2 in S aureus-mediated activation of these cells. METHODS: Conjunctival epithelial cells isolated from cadaveric tissues were stimulated with interferon gamma (IFN-gamma) or a commercial S aureus cell wall extract (Staphylococcus aureus-CWE) (with or without anti-TLR-2 blocking antibody or PAFR antagonist) and were analyzed for tumor necrosis factor alpha (TNF-alpha) and interleukin 8 (IL-8) release; surface expression of TLR-2, intercellular adhesion molecule-1, HLA, and CD14; and TLR-2 messenger RNA expression. Ocular surface cells collected via impression cytology were examined for TLR-2 expression via flow cytometry. RESULTS: Expression of TLR-2 was up-regulated on conjunctival epithelial cells by IFN-gamma and Staphylococcus aureus-CWE. Expression of TLR-2 messenger RNA was increased by IFN-gamma. Staphylococcus aureus-CWE up-regulated intercellular adhesion molecule 1, HLA, and CD14 expression and increased TNF-alpha and IL-8 release in a dose-dependent manner. Anti-TLR-2 significantly inhibited TNF-alpha release, whereas PAFR antagonist significantly inhibited IL-8 release. Toll-like receptor 2 was expressed on conjunctival epithelial cells from 4 of 5 patients with atopic keratoconjunctivitis, 3 of 5 with seasonal allergies, and 0 of 3 without allergies. CONCLUSIONS: Conjunctival epithelial cells express TLR-2 and may play an active role in the chronic ocular inflammatory response to S aureus through pathways that involve TLR-2 and PAFR.

Adolescent↗