Search PubMed⌕ Search

Biomedical subjects

C von Eiff

Publications and source records attributed to C von Eiff.

At least 37 records · Page 2Linked to original sources
PubMed2000

Staphylococcus aureus small colony variants: formation and clinical impact.

S. aureus small-colony variants are a naturally occurring subpopulation which grow slowly and produce small colonies on routine media. They also demonstrate a number of other characteristics that are atypical for S. aureus including reduced alpha-toxin production and delayed coagulase activity. The connection of S. aureus SCVs with persistent and relapsing infections has been defined over the past decade, especially in patients with chronic osteomyelitis and in cystic fibrosis patients as demonstrated by prospective studies. While the studies with clinical isolates of SCVs suggested a link between electron transport-defective strains and persistent infections, a defined hemB mutant with the SCV phenotype provided strong additional evidence for these connections. The hemB mutant was phagocytosed by cultured endothelial cells, but did not lyse these cells, because the mutant produced very little alpha-toxin. The intracellular location may shield the SCVs from host defenses and antibiotics, thus providing one explanation for the difficulty in clearing S. aureus SCVs from host tissues.

Colony Count, Microbial↗
PubMed1999

Reconstructive treatment of sclerosing osteomyelitis of the entire femur of 30 years' duration with avoidance of segmental resection.

We describe the successful operative treatment of a patient with chronic sclerosing osteomyelitis of the femur in which en bloc resection was avoided. Therapy consisted of combined endoscopic, computed tomography and bone scan-guided fenestration and intramedullary reaming, with removal of all sclerotic zones and normalization of the cortical thickness. An adequate supply of oxygen to the area was ensured by improved vascularisation and the application of hydrogen peroxide. At the medium term follow-up no recurrence was seen, and hip and knee function was normal.

Bone Cements↗
PubMed1999

New aspects in the molecular basis of polymer-associated infections due to staphylococci.

Coagulase-negative staphylococci, particularly Staphylococcus epidermidis, cause the majority of infections associated with both temporarily inserted and permanently implanted foreign bodies. In recent years, the pathogenesis of polymer-associated staphylococcal infection has become better understood, due in part to the characterization of further associated factors. The bacterial factors involved in the two phases of biofilm formation, i.e. the rapid adherence of bacteria to the polymer surface and the subsequent, more prolonged, accumulation phase, are presented in this review. The biofilm present on infected devices plays an important role in the pathogenicity of the infecting organism by protecting the embedded staphylococci and reducing the efficacy of host defenses and antimicrobial killing.

Bacterial Adhesion↗
PubMed1999

Bloodstream infections caused by small-colony variants of coagulase-negative staphylococci following pacemaker implantation.

Small-colony variants (SCVs) of Staphylococcus aureus cause persistent and relapsing infections. Relatively little is known regarding infections caused by SCVs of coagulase-negative staphylococci. We report two cases of pacemaker electrode infections due to SCVs of Staphylococcus epidermidis and Staphylococcus capitis. Sequence analysis of a portion of the 16S rRNA gene (16S rDNA) confirmed the identity of the staphylococcal species as S. capitis and S. epidermidis. Isolates from cultures of blood obtained over at least a 2-week interval were compared by pulsed-field gel electrophoresis and found to be clonal even though the colony morphology was very different. Analysis for auxotrophism revealed hemin dependencies for all isolated SCVs. The two cases have several clinical and laboratory characteristics (which are also seen with S. aureus SCV infections) and strongly suggest that SCVs of coagulase-negative staphylococci must be actively sought, because they grow very slowly and can be easily missed.

Bacteremia↗
PubMed1999

Comparative in-vitro activities of moxifloxacin, trovafloxacin, quinupristin/dalfopristin and linezolid against staphylococci.

The antistaphylococcal activities of four newly developed antibiotics, moxifloxacin (an 8-methoxyfluoroquinolone), trovafloxacin (a naphthyridone), quinupristin/dalfopristin (a semisynthetic streptogramin) and linezolid (an oxazolidinone), were examined and compared with those of ciprofloxacin, vancomycin and teicoplanin, using an agar dilution method. A total of 245 clinical isolates of staphylococci, including a large number of clonally different methicillin-resistant strains, were tested. The new agents tested exhibited wide-spectrum antistaphylococcal activity against both methicillin-susceptible and methicillin-resistant strains. In contrast to the quinolones, the in-vitro activities of quinupristin/dalfopristin, linezolid and the glycopeptides remained almost unchanged, irrespective of the resistance phenotype for methicillin. A number of isolates with elevated quinolone MICs were observed.

Acetamides↗
PubMed1999

Detection of Staphylococcus aureus and Staphylococcus epidermidis in clinical samples by 16S rRNA-directed in situ hybridization.

Staphylococcus epidermidis and Staphylococcus aureus are the most common causes of medical device-associated infections, including septicemic loosenings of orthopedic implants. Frequently, the microbiological diagnosis of these infections remains ambiguous, since at least some staphylococci have the capacity to reduce their growth rate considerably. These strains exhibit a small-colony phenotype, and often they are not detectable by conventional microbiological techniques. Moreover, clinical isolates of S. aureus and S. epidermidis adhere to polymer and metal surfaces by the generation of thick, multilayered biofilms consisting of bacteria and extracellular polysaccharides. This study reports improved detection and identification of S. aureus and S. epidermidis by an in situ hybridization method with fluorescence-labeled oligonucleotide probes specific for staphylococcal 16S rRNA. The technique has proven to be suitable for the in situ detection of staphylococci, which is illustrated by the identification of S. epidermidis in a connective tissue sample obtained from a patient with septicemic loosening of a hip arthroplasty. We also show that this technique allows the detection of intracellularly persisting bacteria, including small-colony variants of S. aureus, and the differentiation of S. epidermidis from other clinically relevant staphylococci even when they are embedded in biofilms. These results suggest that the 16S rRNA in situ hybridization technique could represent a powerful diagnostic tool for the detection and differentiation of many other fastidious microorganisms.

Genes, rRNA↗
PubMed1998

Staphylococcal small colony variants have novel mechanisms for antibiotic resistance.

Over the past 4 years, a variant subpopulation of Staphylococcus aureus has been characterized that is defective in electron transport. These organisms grow slowly and are typical of the previously described small colony variants (SCVs). Indeed, many earlier papers included data that are consistent with defective respiratory activity in SCVs. We present a hypothesis that serves as biochemical basis for the development of SCVs. These variants are particularly interesting because they have been associated with very persistent infections, and they are more resistant to many antibiotics than normal S. aureus. Because of their slow growth, atypical colonial morphology, and unusual biochemical profile, they are easily missed or misidentified in the clinical laboratory. This is of some significance, as this subpopulation is more resistant to antibiotics than the parent population from which they arose. When an infection is particularly resistant to therapy, persists for a long period, or fails to respond to apparently adequate antimicrobial therapy, clinicians and clinical laboratory personnel should consider special efforts to search for SCVs.

Animals↗
PubMed1997

Left ventricular assist device infection is associated with increased mortality but is not a contraindication to transplantation.

BACKGROUND: Left ventricular assist devices (LVADs) are increasingly used as a bridge to transplantation. Infection is a frequent and major complication associated with the use of these devices, however, the correlation of infection and outcome has not yet been evaluated in a prospective fashion. METHODS AND RESULTS: Twenty-five patients (24 male, 1 female) with end-stage cardiac failure and resulting organ dysfunction were included. Patients were bridged with the Novacor N100 portable LVAD (median duration of support, 55 days) and were evaluated prospectively by device surface cultures on explantation, molecular typing of isolates, and correlation of infection with survival to transplant. Twelve (48%) of 25 patients had LVAD infection as defined by recovery of multiple isolates of identical genotype from the device surface. Whereas only 5 (42%) of 12 patients with LVAD infection survived until transplantation, 11 (85%) of 13 patients without infection were successfully transplanted (P < .05). Death of the 7 patients with proven LVAD infection was associated with multiple organ failure or other signs of acute infection. CONCLUSIONS: LVAD infection is associated with a significantly decreased survival probability. It does not preclude successful bridging but rather may pose an indication for urgent transplantation.

Adult↗
PubMed1997

A 140-kilodalton extracellular protein is essential for the accumulation of Staphylococcus epidermidis strains on surfaces.

Two distinct pathogenic mechanisms, adhesion to polymer surfaces and subsequent accumulation of sessile bacterial cells, are considered important pathogenic steps in foreign body infections caused by Staphylococcus epidermidis. By using mitomycin mutagenesis, we have recently generated a mutant, strain M7, from S. epidermidis RP62A which is unaffected in adhesion but deficient in accumulation on glass or polystyrene surfaces and lacks a 115-kDa extracellular protein (designated the 140-kDa antigen; F. Schumacher-Perdreau, C. Heilmann, G. Peters, F. Götz, and G. Pulverer, FEMS Microbiol. Lett. 117:71-78, 1994). To evaluate the role of this protein in accumulation, we harvested extracellular proteins from S. epidermidis RP62A grown on dialysis membranes placed over chemically defined medium, purified the protein by using ion-exchange chromatography, determined its N-terminal amino acid sequence, and raised antiserum in rabbits. The antibody recognized only a single band in a Western immunoblot of the crude extracellular extract. With the microtiter biofilm test, antiserum at a dilution of < or =1:1,000 blocked accumulation of RP62A up to 98% whereas preimmune serum did not. The 140-kDa antigen was found only in extracellular products from bacteria grown under sessile conditions. Of 58 coagulase-negative clinical isolates, 32 strains were 140-kDa antigen positive and produced significantly larger amounts of biofilm than the 26 strains that were 140-kDa antigen negative. The 140-kDa protein appears to be biochemically and functionally unrelated to any previously described factors associated with biofilm formation. Thus, the 140-kDa antigen, referred to as accumulation-associated protein, may be a factor essential in S. epidermidis accumulation and, due to its immunogenicity, may allow the development of novel immunotherapeutic strategies for prevention of foreign body infection.

Amino Acid Sequence↗
PubMed1997

A site-directed Staphylococcus aureus hemB mutant is a small-colony variant which persists intracellularly.

Although small-colony variants (SCVs) of Staphylococcus aureus have been recognized for many years, this phenotype has only recently been related to persistent and recurrent infections. Clinical S. aureus SCVs are frequently auxotrophic for menadione or hemin, two compounds involved in the biosynthesis of the electron transport chain elements menaquinone and cytochromes, respectively. While this observation as well as other biochemical characteristics of SCVs suggests a link between electron-transport-defective strains and persistent infections, the strains examined thus far have been genetically undefined SCVs. Therefore, we generated a stable mutant in electron transport by interrupting one of the hemin biosynthetic genes, hemB, in S. aureus by inserting an ermB cassette into hemB. We isolated a hemB mutant, due to homologous recombination, by growth at a nonpermissive temperature and selection for erythromycin resistance. This mutant showed typical characteristics of clinical SCVs, such as slow growth, decreased pigment formation, low coagulase activity, reduced hemolytic activity, and resistance to aminoglycosides. Additionally, the mutant was able to persist within cultured endothelial cells due to decreased alpha-toxin production. Northern and Western blot analyses showed that expression of alpha-toxin and that of protein A were markedly reduced, at both the mRNA and the protein level. The SCV phenotype of the hemB mutant was reversed by growth with hemin or by complementation with intact hemB. Hence, a defect in the electron transport system allows S. aureus SCVs to resist aminoglycosides and persist intracellularly.

Aminoglycosides↗
PubMed1996

Hospital-acquired candida and aspergillus pneumonia--diagnostic approaches and clinical findings.

Bronchoscopy with bronchoalveolar lavage (BAL), collection of bronchial secretions (BS) and/or high resolution computed tomography (CT) of the lungs was performed in 70 patients with candida and/or aspergillus pneumonia. The sensitivity of bronchoscopy in detecting histologically proven fungal disease was 59%. Characteristic CT signs were found in 11 of 14 patients with candida pneumonia and 16 of 19 patients with aspergillosis. The more frequent use of bronchoscopy and CT scans between 1990 and 1992 compared with 1986-1989 for the differential diagnosis of new pulmonary infiltrates in immunocompromised patients resulted in earlier antifungal treatment (14 vs. nine days; P < 0 center dot 025). In the second treatment period survival was improved from 36 to 50% (not significant). Bronchoscopy and high resolution CT scans are mutually complementary diagnostic tools and should be performed as early as possible in the course of pneumonia in patients at high risk of fungal diseases.

Adolescent↗
PubMed1996

In-vitro activity of RP 59500, a new semisynthetic injectable pristinamycin against staphylococci.

We compared the in vitro activity of RP 59500, a new streptogramin, with that of vancomycin and ciprofloxacin against 130 strains of S. aureus and 117 strains of coagulase-negative staphylococci, using the agar dilution method. The antistaphylococcal activity of RP 59500 was similar to that of vancomycin. All staphylococcal strains were inhibited by < or = 2 micrograms/mL, including 61 methicillin-resistant S. aureus, 28 methicillin-resistant S. epidermidis and 23 methicillin-resistant S. haemolyticus strains. In contrast to ciprofloxacin, the in vitro activity of RP 59500 as well as of vancomycin remained almost unchanged, irrespective of the resistance phenotype for methicillin.

Anti-Bacterial Agents↗
PubMed1996

In-vitro activity of ofloxacin, levofloxacin and D-ofloxacin against staphylococci.

The in-vitro activity of levofloxacin was compared with ofloxacin and D-ofloxacin against 130 isolates of Staphylococcus aureaus and 117 isolates of coagulase-negative staphylococci, using the agar dilution method. In general, levofloxacin was equally active or up to fourfold more active than ofloxacin against all staphylococci, including 61 methicillin-resistant S. aureus. In contrast, D-ofloxacin showed little activity against all isolates tested.

Anti-Infective Agents↗