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Biomedical subjects

U Fluckiger

Publications and source records attributed to U Fluckiger.

10 recordsLinked to original sources
PubMed2000

Clinical impact of an infectious disease service on the management of bloodstream infection.

The impact of an infectious disease (ID) service on the optimal antibiotic management of 103 patients with bloodstream infections, defined as bacteremia and systemic inflammatory response syndrome, was evaluated. The optimal antibiotic management was defined according to the Sanford Guide to Antimicrobial Therapy (1996) or written internal guidelines. The judgment on optimal antibiotic management was made at the time of reporting the positive blood culture results. Switching from a broad-spectrum to a narrow-spectrum agent was carried out significantly more often by the ID service than by the attending physicians (25 of 25 vs. 20 of 40; P<0.001). In patients without empirical therapy, the ID service initiated optimal antimicrobial therapy significantly more often than physicians without training in infectious diseases (12 of 12 vs. 4 of 10, P=0.0028). Three of 12 patients in whom the attending physician misinterpreted the positive blood culture result needed 8 days to 4 months of additional hospitalization. In summary, patients for whom an ID service was provided received appropriate treatment more often and experienced significantly fewer complications.

Adult↗
PubMed2000

C-reactive protein and fever in neutropenic patients.

The predictive value of daily C-reactive protein (CRP) monitoring to distinguish causes of fever in neutropenic patients was studied retrospectively. A total of 143 fever episodes during 113 consecutive hospitalizations were studied in 71 patients who had been referred for chemotherapy or haemopoietic stem cell transplantation (HSCT). There were, on average, 1.3 fever episodes per hospital stay, attributed to: infection (55, 27 invasive bacterial, 5 fungal, 3 viral and 20 probable infections); acute graft vs host disease (GvHD) (20); drugs (22); transfusions (7); and not attributable (39). 130 (91%) fever episodes were accompanied by a rise in CRP, 6 (4%) episodes were fatal. Maximal CRP levels (CRPmax) and maximal temperature (Tmax) were higher in invasive bacterial infections than in aGvHD and higher in aGvHD than in drug- or transfusion-related fever (p < 0.0001). Temperature and CRP rose in parallel. A total of 16 patients developed grade II-IV aGvHD by day 11 (9-21) (median, range) after allogeneic HSCT. Acute GvHD was preceded by fever for 3 d (1-7), and by CRP increase for 5 d (0-15) (p < 0.0001). CRP monitoring may be useful to distinguish between causes of fever. Very high CRP levels tend to be associated with invasive bacterial infections. CRP is not an early warning sign. An increase in CRP and fever may precede other clinical manifestations of aGvHD.

Adolescent↗
PubMed1998

Immunoglobulins to group A streptococcal surface molecules decrease adherence to and invasion of human pharyngeal cells.

The M protein is one of the most important virulence factors of group A streptococci (Streptococcus pyogenes) and may play an important role in the first steps of streptococcal infection. Since acute pharyngitis is a frequently occurring infectious disease caused by these bacteria, we wished to know whether antibodies to the M protein or other surface components inhibit adherence and internalization of streptococci to pharyngeal cells. We investigated the role of whole human secretory immunoglobulin A (sIgA), M6 protein-specific sIgA, and M6 protein-specific serum IgG in the inhibition of streptococcal adherence and internalization to cultured human pharyngeal cells. S. pyogenes D471, which produces a type 6 M protein (M+), and its isogenic M-negative (M-) derivative JRS75 were tested. Purified whole sIgA, M protein-specific sIgA, and sIgA preabsorbed with M protein were able to decrease significantly the adherence of streptococci to pharyngeal cells. Purified IgG against the M6 protein did not diminish the attachment of streptococci to the pharyngeal cells but did reduce internalization. Thus, our data suggest that secretory IgA may play a key role in preventing streptococcal infection at mucosal surfaces by blocking adherence while affinity-purified anti-M protein-specific IgG blocks epitopes responsible for invasion.

Animals↗
PubMed1998

Characterization of a sar homolog of Staphylococcus epidermidis.

Coagulase-negative staphylococci are common nosocomial pathogens. A regulatory element, designated sar, partially controls exoprotein synthesis in coagulase-positive Staphylococcus aureus by modulating the expression of another regulatory locus, called agr. We report here the cloning of a sar homolog in S. epidermidis. The major open reading frame within sar in S. epidermidis is highly homologous (84%) to the S. aureus SarA protein. Primer extension studies revealed three sar transcripts (0.64, 0.76, and 0.85 kb) initiated from three distinct promoters. The interpromoter region in S. epidermidis differs from its S. aureus counterpart, possibly suggesting target gene differences and a disparate pattern for sar activation. Remarkably, the S. epidermidis sar homolog interacts with an agr promoter fragment of S. aureus in gel shift assays. Additionally, S. epidermidis sar fragments could restore hemolysin production in an S. aureus sar mutant. As typical virulence determinants controlled by sar in S. aureus are not present in S. epidermidis, an examination of functional and structural similarities and divergence of sar in staphylococci will be of major interest.

Amino Acid Sequence↗
PubMed1997

Immunoglobulins inhibit adherence and internalization of Streptococcus pyogenes to human pharyngeal cells.

Purified human sIgA against group A streptococci inhibited streptococcal adherence to pharyngeal cells whereas rabbit serum raised against the whole M+ strain did not. Of note, inhibition of adherence by sIgA occurred despite a much lower immunreactivity against the M6 protein as compared to the hyperimmune serum against the whole M+ strain. The M protein does probably not mediate the adherence of group A streptococci to respiratory cells, as shown by previous studies. However, since the isogenic M- derivative was less invasive to human pharyngeal cells than the M+ strain, our invasion experiments suggest that the M protein may play a role in internalization of group A streptococci into eukaryotic cells. More importantly, internalization and not adherence could be blocked by rabbit serum immunized with recombinant M6 protein.

Animals↗
PubMed1994

Role of amoxicillin serum levels for successful prophylaxis of experimental endocarditis due to tolerant streptococci.

The importance of amoxicillin serum profiles for successful prophylaxis of experimental endocarditis in rats was assessed. Animals with catheter-induced vegetations were challenged intravenously with large inocula of Streptococcus sanguis and received one of the following amoxicillin dosages: single or multiple bolus injection of 40 mg/kg; 40 mg/kg administered as a continuous infusion over 12 h; or either 9 or 18 mg/kg administered over 12 or 24 h, respectively. The regimen producing a single transient high peak serum level failed to prevent experimental endocarditis; in contrast, a second injection 6 h after the first resulted in successful prophylaxis. Likewise, the three regimens of continuous, relatively low-dose regimens prevented infections. Thus, the most important parameter for successful prophylaxis was the duration of inhibitory concentration of the drug in the serum. The total dose of antibiotic, the peak serum levels, or the area-under-the-curve values were not predictive of successful prophylaxis.

Amoxicillin↗
PubMed1994

Antibiotic treatment of experimental endocarditis due to methicillin-resistant Staphylococcus epidermidis.

The natural history and treatment of experimental endocarditis due to heterogeneous and homogeneous methicillin-resistant Staphylococcus epidermidis was investigated. Amoxicillin/clavulanate or vancomycin were administered for 3 days via a computerized pump to mimic human drug kinetics in animals. After challenge with the minimum inoculum producing 90% of infections (ID90), bacteria in the vegetations grew logarithmically for 16 h. Then, bacterial densities stabilized (at approximately 10(8) cfu/g) and growth rates sharply declined. Both regimens cured > or = 60% of endocarditis (due to heterogeneous or homogeneous bacteria) when started 12-16 h after infection, although the bacterial densities in the vegetations had increased by 20 times in between. In contrast, treatment started after 24 h failed in most animals, while bacterial densities had not increased any more. Thus, while both regimens were equivalent, the therapeutic outcome was best predicted by growth rates in the vegetations, not by bacterial densities. These observations highlight the importance of phenotypic tolerance developing in vivo.

Amoxicillin↗
PubMed1994

Simulation of amoxicillin pharmacokinetics in humans for the prevention of streptococcal endocarditis in rats.

The pharmacokinetic determinants of successful antibiotic prophylaxis of endocarditis are not precisely known. Differences in half-lives of antibiotics between animals and humans preclude extrapolation of animal results to human situations. To overcome this limitation, we have mimicked in rats the amoxicillin kinetics in humans following a 3-g oral dose (as often used for prophylaxis of endocarditis) by delivering the drug through a computerized pump. Rats with catheter-induced vegetations were challenged with either of two strains of antibiotic-tolerant viridans group streptococci. Antibiotics were given either through the pump (to simulate the whole kinetic profile during prophylaxis in humans) or as an intravenous bolus which imitated only the peak level of amoxicillin (18 mg/liter) in human serum. Prophylaxis by intravenous bolus was inoculum dependent and afforded a limited protection only in rats challenged with the minimum inoculum size infecting > or = 90% of untreated controls. In contrast, simulation of kinetics in humans significantly protected animals challenged with 10 to 100 times the inoculum of either of the test organisms infecting > or = 90% of untreated controls. Thus, simulation of the profiles of amoxicillin prophylaxis in human serum was more efficacious than mere imitation of the transient peak level in rats. This confirms previous studies suggesting that the duration for which the serum amoxicillin level remained detectable (not only the magnitude of the peak) was an important parameter in successful prophylaxis of endocarditis. The results also suggest that single-dose prophylaxis with 3 g of amoxicillin in humans might be more effective than predicted by conventional animal models in which only peak levels of antibiotic in human serum were stimulated.

Amoxicillin↗
PubMed1993

Simulated human serum profiles of one daily dose of ceftriaxone plus netilmicin in treatment of experimental streptococcal endocarditis.

We performed experiments in rats aimed at determining whether a combination of ceftriaxone (CRO) and netilmicin (NET), by using once-daily administration in rats, which simulated profiles of drug in human serum, was more effective than either agent alone in the treatment of endocarditis caused by viridans group streptococci. A programmable infusion pump system enabled the production of profiles of CRO in serum that simulate those found in humans after the intravenous administration of 2 g. The subcutaneous administration of 18 mg of NET per kg of body weight produced levels in the sera of rats comparable to those after the intravenous administration of a dose of 5 mg of NET per kg in humans. Rats with catheter-induced aortic vegetations were infected intravenously with two test strains, a CRO-susceptible Streptococcus sanguis strain (MICs of CRO and NET, 0.064 and 8 mg/liter, respectively) and a relatively CRO-resistant Streptococcus mitis strain (MICs of CRO and NET, 2 and 8 mg/liter, respectively). Against both strains, the combination of CRO and NET was synergistic in vitro as determined by time-kill curves. Treatment of rats was started 48 h postinfection and lasted for 3 days. CRO alone was effective against the susceptible strain (P < 0.001 compared with control animals) but was not effective against the resistant organism. A significantly enhanced antibacterial activity of the CRO-NET combination in reducing the valvular bacterial counts was observed with both test strains (P < 0.001). The synergistic effect was obtained with a single daily injection of NET which provided detectable levels in serum for only 8 h, suggesting that in vivo synergism in the treatment of infections caused by viridans group streptococci can be obtained without 24 h of aminoglycoside coverage. These experimental data might provide a rationale for clinical trials of a once-a-day dosing regimen in the treatment of streptococcal but nonenterococcal endocarditis.

Animals↗