Oral source of Staphylococcus epidermidis septicemia in a neutropenic patient.
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Biomedical subjects
Publications and source records attributed to J Etienne.
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An antibiotic prophylaxis of infective endocarditis is recommended in patients at high risk for infective endocarditis (patients with valvular prosthesis, or cyanogen congenital or obstructive cardiac defect) or those with aortic, mitral or tricuspid valvulopathy, a non-cyanogen congenital or obstructive cardiac defect. Dental procedures (except treatment for superficial decay and preparation for the fitting of prostheses to teeth with intact pulp) are to be carried out under local antisepsis and a prophylactic antibiotics, such as 3 g of oral amoxicillin or in case of allergy to penicillin, 600 mg of clindamycin or 1g of pristinamycin, administered one hour prior to the procedure. A similar prophylaxis is recommended for the procedures on the upper respiratory tract. Amoxicillin, or vancomycin or teicoplanin are recommended for procedures under general anaesthesia. For surgery on the intestinal or urogenital tract, regimens combine amoxicillin with gentamicin, or in case of allergy to penicillin, vancomycin or teicoplanin with gentamicin.
Cardiac surgery enters mainly into the class I of Altemeier ("clean surgery"). However, many factors may explain an intraoperative contamination: surgery of long duration, extra-corporeal circulation, aspiration of blood and air, immunodepression...). In fact, the infectious risk decreases from about 25% with placebo to 5% with prophylactic antibiotics. The staphylococcal infections are the most frequent (mediastinitis, endocarditis, parietal infections...). Cephalosporins, particularly of second-generation type (cefamandole, cefuroxime), perform better than antistaphylococcal penicillins. The combination with an amino-side may be used when Gram negative bacilli infection prevalence is high. Vancomycin is efficient but hypotension and renal impairment have been reported. Therefore, vancomycin is used in patients allergic to cephalosporins, when a high prevalence of methicillin-resistant Staphylococcus or enterococci infections is reported, or when the patient has recently received broad-spectrum antimicrobial therapy. The antibiotic doses must take into account the haemodilution due to extracorporeal circulation and the necessity to obtain sufficient serum concentrations throughout surgery. A prophylaxis of more than 48 hours is not associated with an improved outcome. In cardiac transplantation a prophylaxis is essential, but is still questioned during the insertion of pace-markers. In any case, the antibiotic prophylaxis must take into account the bacterial prevalence of each institution.
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The molecular basis of the non-expression of coagulase was investigated for 14 coagulase-negative isolates of Staphylococcus aureus obtained from different clinical samples. These isolates had typical S. aureus characteristics such as production of clumping factor, DNAase and protein A, but, with one exception, failed to produce detectable amounts of alpha-haemolysin. All 14 strains had DNA homologous to the coagulase gene (coa), but a coa-specific transcript was found in only seven of them. alpha-Haemolysin mRNA was detected in only eight strains without direct correlation to coa-mRNA expression. Thus, coagulase and alpha-haemolysin deficiencies in S. aureus may involve either transcriptional or post-transcriptional alterations although additional regulatory factors may influence the expression of both genes.
Expression of staphylocoagulase by agr+ Staphylococcus aureus depends on the growth phase, being maximal during exponential growth and decreasing sharply postexponentially, while an agr-deleted strain continuously expresses an intermediate level of coagulase. Therefore, coagulase expression appears to be both positively and negatively modulated by an agr-dependent mechanism.
Staphylococcus schleiferi subsp. schleiferi is a coagulase-negative staphylococcus, usually present as a contaminant in human specimens. A near relative, S. schleiferi subsp. coagulans, possesses coagulase activity but has not been reported from humans. We here describe three isolates of pseudocoagulase-positive S. schleiferi subsp. schleiferi and one isolate of S. schleiferi subsp. coagulans from human patients. The pseudocoagulase from the S. schleiferi subsp. schleiferi isolates differs from S. aureus staphylocoagulase by being sensitive to a combination of protease inhibitors (aprotinin, N-ethylmaleimide, and heparin). These isolates could all easily be confused with S. aureus in a typical clinical laboratory, since they all possess a heat-stable DNase and promote clotting formation. Moreover, S. schleiferi subsp. coagulans produces protein A, and S. schleiferi subsp. schleiferi expresses a clumping factor (fibrinogen affinity factor). Southern blot hybridization with an S. aureus coa-specific probe revealed no sequence related to the coa gene in any of the S. schleiferi isolates, and their riboprobe profiles and biochemical characteristics were typical of S. schleiferi subspecies, not of S. aureus. This study demonstrates that both subspecies of S. schleiferi can promote clotting of rabbit plasma in the standard tube test for coagulase.
A commensal organism of the buccal cavity, Actinobacillus actinomycetemcomitans (AAC) has been responsible for at least four new cases of infectious endocarditis by year in France. This retrospective study was based on 90 new cases of infectious endocarditis by AAC, including 8 personal observations. One third of patients had no known cardiac disease before their infectious endocarditis, the portal of entry of which was usually dental. In cases of suspected infectious endocarditis, rapid and severe weight loss (43% of cases) and, less commonly, anicteric cholestasis (8%) should alert the physician for the possible pathological role of AAC. The echocardiographic appearances are non-specific. The diagnosis is confirmed on blood cultures but the organism grows slowly in CO2 enriched atmosphere. Initially, the course of the disease was favourable in one third of patients but, in two thirds of cases, complications were observed almost renal (26%), cardiac (24%) and neurological (18%). Two thirds of patients were cured by the time they were discharged whereas the remainder had sequellae, mainly valvular and neurological. The hospital mortality was 9%; late mortality was 6%. Therefore, the prognosis of AAC endocarditis, seems to be better than that of other bacteriological forms. A combination of cephalosporin and aminoside, or even a simple third generation cephalosporin antibiotic therapy for at least 4 weeks are usually effective. The complementary surgical indications are the same as for other forms of infectious endocarditis. Prophylaxis depends on strict prophylactic amoxicillin therapy for all cardiac patients at risk of infectious endocarditis before dental treatment and on good bucco-dental hygiene.
The objective of this study was to investigate in vivo the effects of various durations of hyperinsulinemia on inguinal white adipose tissue lipoprotein lipase (LPL). Adult genetically-obese (fa/fa) rats were used as a model of chronic hyperinsulinemia. Normal rats infused with insulin as well as with glucose to maintain euglycemia for four days were used as a model of short-term hyperinsulinemia. Normal rats studied during a euglycemic-hyperinsulinemic clamp were used as a model of acute effects of hyperinsulinemia. The levels of LPL mRNA, LPL protein and LPL total activity in inguinal white adipose tissue were measured. In both chronic and long-term hyperinsulinemia, a marked increase in total LPL activity was observed which was associated with an increase in tissue LPL protein abundance. After five hours of hyperinsulinemia, as achieved during the clamps, only total LPL activity was increased. An increase in LPL mRNA was measured only in adipose tissue of obese rats. The differences observed in the regulation of LPL mRNA between insulin-treated rats and genetically-obese animals may be explained either by the large increase in adipose tissue glucose metabolism of insulin-treated rats compared to obese rats and/or by other factors that may be present in genetically-obese (fa/fa) rats.
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Sequences related to the Staphylococcus aureus accessory gene regulator (agr) were demonstrated in S. lugdunensis by Southern blot analysis of 13 strains and sequencing of the S. lugdunensis agr-like locus (agr-sl). Northern blot analysis of cellular RNA revealed the presence of a transcript having homology with the agr-P3 transcript (RNAIII) for three of the six strains tested. The three strains containing this transcript produce a hemolysin with phenotypic properties similar to that of S. aureus delta-hemolysin. Nevertheless, unlike agr-P3 from S. aureus, agr-sl does not encode any potential peptide homologous to S. aureus delta-hemolysin, suggesting that the hemolytic activity detected in S. lugdunensis is encoded elsewhere and may be controlled by agr-sl.
DNA analysis using pulsed-field gel electrophoresis (PFGE) has emerged as one of the most sensitive epidemiological tools for the characterization of coagulase-negative staphylococci (CNST). The significance of some minor differences observed between the DNA restriction pulsed patterns of two CNST strains are difficult to interpret since they can theoretically be due to minor chromosomal rearrangements or to phage DNA integration. The latter possibility was investigated by comparing DNA restriction patterns of Staphylococcus epidermidis strains with those of their lysogenized derivatives. In vitro lysogenisation was obtained by exposing the strains to phage 118II. The pulsed patterns of the lysogenized strains were compared to those of their parental strains, revealing a shift in size of approximately 50 kb in a single band which was shown by Southern blotting to contain prophage. One strain was lysogenized ten times, revealing a potential preferred attachment site for phage 118II. These results confirm that chromosomal integration of a phage can be responsible for minor stable variations in DNA restriction patterns.
OBJECTIVE: Chronic Q fever is seldom recognized; before 1989, only 234 cases had been reported in the literature. The 92 cases of chronic Q fever collected at the French National Reference Center for Rickettsioses from 1982 through 1990 represent the largest series ever reported. PATIENTS: The patients included in the study were diagnosed between July 31, 1982, and August 1, 1990, at the French National Reference Center for Rickettsioses as having chronic Q fever by the following criteria: presence of antibody against Coxiella burnetii phase I antigen at a titer greater than or equal to 800 for IgG and 50 for IgA by the indirect immunofluorescence test. Epidemiologic, clinical, laboratory, and treatment data were collected from 39 different collaborative hospitals throughout France. MAIN OUTCOME MEASURE: For each serologically selected patient, a computerized questionnaire was utilized to record 188 different items of demographic, epidemiologic, clinical, laboratory, and therapeutic data, which were analyzed. RESULTS: Chronic Q fever occurs more frequently in city dwellers than in rural inhabitants, and exposure to domestic ruminants and raw milk is an important feature. Immunocompromising conditions (20.2%) and underlying heart disease (88.4%) or vascular disease are the most important risk factors to consider in potential cases of chronic Q fever. The mortality in these patients with endocarditis was high (23.5%). The clinical spectrum of 84 patients included 57 cases of endocarditis, three cases of vascular prosthesis infection, three cases of aneurysmal infection, three cases of osteoarthritis, four cases with lung localizations, nine asymptomatic cases, three cases of hepatitis, and two cases with cutaneous forms of the disease. CONCLUSIONS: In patients with unexplained fever, negative blood cultures, and a history of underlying vascular or cardiac disease, Q fever should be considered.
Clusterin (gene symbol: CLI) is a post-translationally nicked, two-chain plasma and tissue glycoprotein of 80 kDa. It forms high-density lipoprotein complexes with apolipoprotein A-I in plasma, functions as an inhibitor of the cytolytic reaction of the terminal complement proteins C5 to C9, and is secreted by Sertoli cells in large amounts into the seminal fluid. By isolating and characterizing three partially overlapping cosmid clones, we have established the complete physical map of the clusterin gene which spans about 20 kb. The subchromosomal position of the clusterin gene (CLI) and the order of CLI and the lipoprotein lipase (LPL) gene were determined by fluorescence in situ hybridization. We show that CLI, previously assigned to chromosome 8, is located on 8p21 proximal to the LPL locus. Based on this localization we consider clusterin as a novel candidate gene determining susceptibility to atherosclerosis.
Several different epidemiological typing methods have been used in studies of coagulase-negative staphylococci; these include biotyping, antibiotic susceptibility pattern analysis, serological typing, phage typing, slime production detection, protein profile analysis, immunoblot fingerprinting and DNA typing. The most frequently used tests are antibiotic susceptibility and extrachromosomal DNA banding patterns. Comparison of chromosomal DNA restriction patterns is facilitated when the fragments are separated by pulsed-field electrophoresis. Typing variations occur quite frequently even in isolates of demonstrated clinical significance. Caution should therefore be exercised in denying the clinical relevance of coagulase-negative staphylococci, even when successive isolates show distinct typing differences.
Staphylococcus lugdunensis is a recently described coagulase-negative staphylococcus that has been associated with human infections, including nine reported cases of infective endocarditis. The present study describes 11 other cases of infective endocarditis caused by this organism. The infection occurred in patients whose mean age was 61 years and was community-acquired in most cases. A preexisting cardiac abnormality was present in eight patients. Three of the 11 infections involved prosthetic valves. Ten strains were susceptible to penicillin. The destructive course of the infection, the need for valve replacement, and the high mortality suggest that S. lugdunensis causes a virulent form of endocarditis.
The molecular characteristics of 31 unrelated strains of Staphylococcus schleiferi isolated from 13 hospitals between 1973 and 1991 were determined by ribosomal DNA fingerprinting by using a digoxigenin-labeled DNA probe, genomic DNA restriction patterns, and plasmid profiles. Only six strains harbored one or two plasmids. DNA restriction analysis, which was carried out with five endonucleases (EcoRI, HindIII, PstI, PvuII, and ClaI), did not allow us to discriminate between isolates. Ribotyping with HindIII, ClaI, or EcoRI enzymes generated six, seven, and nine distinct patterns, respectively. With the combination ClaI-EcoRI, 13 ribotypes were obtained among the 31 strains, suggesting a relative heterogeneity within the species. Moreover, all strains shared two or three common bands, according to the endonuclease used, which were relatively specific for S. schleiferi in comparison with the ribosomal banding patterns described for other coagulase-negative staphylococci. These results illustrate that ribotyping can be used for the epidemiological investigation of S. schleiferi isolates and possibly for taxonomic analysis in this species.