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A C Rodloff

Publications and source records attributed to A C Rodloff.

At least 55 records · Page 3Linked to original sources
PubMed1997

Use of polymerase chain reaction fingerprinting to compare clinical isolates of Bacteroides fragilis and Bacteroides thetaiotaomicron from Germany and the United States.

Accurate identification of Bacteroides species is often problematic. Therefore, we used a polymerase chain reaction (PCR) fingerprinting technique with either a single nonspecific primer derived from tDNA intergenic spacer or a single primer that anneals to mini- and microsatellite DNA sequences to compare 34 clinical isolates of B. fragilis and 21 clinical isolates of B. thetaiotaomicron from Southern California with 32 clinical isolates of B. fragilis and 10 isolates of B. thetaiotaomicron from Germany. All German B. fragilis isolates (32 of 32) formed one PCR fingerprint group that matched the PCR profile of the B, fragilis reference strain ATCC (American Type Culture Collection) 25285, representative of DNA homology group I. In contrast, the isolates from Southern California formed two PCR fingerprint groups. Although most of these strains (29 of 34) also matched B. fragilis ATCC 25285, some strains (4 of 34) matched the DNA homology group II reference strain VPI (Virginia Polytechnic Institute) 2393. One of the 34 strains showed a unique profile. German B. thetaiotaomicron strains (10 of 10) formed one PCR fingerprint group, matching the reference strain B. thetaiotaomicron ATCC 29742, whereas the B. thetaiotaomicron isolates from Southern California showed heterogenous profiles.

Bacteroides↗
PubMed1997

[Aspects of calculated and controlled antibiotic therapy].

Strategies for selection of antimicrobial agents may include estimation of the most appropriate agent (empirical therapy), or planned escalation or de-escalation therapy. Severe and life-threatening infections such as peritonitis have a particularly poor prognosis if the initial therapy fails. Hence, in these cases a de-escalation therapy employing broad spectrum agents with proven high efficacy should be employed, and selection pressure arguments and cost considerations should be immaterial. After 48 to 72 hours, this initial therapy should be reconsidered (de-escalated to less powerful agents), especially in light of the microbiological test results.

Anti-Bacterial Agents↗
PubMed1996

[Comparative study of the cost-/effectiveness relationship of initial therapy with imipenem/cilastatin in nosocomial pneumonia. Group study].

AIM OF THE STUDY: The present study assessed the total cost involved in the therapy of nosocomial pneumonia. Cost for patients receiving Imipenem as initial antibiotic therapy was compared with that for patients treated by selected alternative regimens. Secondary objectives included the evaluation of fever days, days of antibiotic therapy, days at ICU and days of overall hospitalisation required for the treatment of the nosocomial pneumonia for both methods of treatment. METHODS: A prospective randomised open study involving multiple study sites was conducted. Total cost, efficacy and safety of an initial therapy with Imipenem were compared to results achieved with selected other antibiotic regimens. Altogether 109 patients were enrolled into the study; 85 patients could be assessed. RESULTS: Both treatment methods showed equal clinical efficacy. Total cost of the therapy of nosocomial pneumonia for all patients was in the range between 1,616 DM and 82,141 DM, the arithmetic mean was calculated to be 11,307 DM and the median was found to be 6,507 DM. Imipenem-treated patients incurred lower cost (median 5,649 DM, mean 10,009 DM) than patients treated with other antibiotics (median 9,334 DM, mean 12,701 DM). CONCLUSION: The total cost of treatment of nosocomial pneumonia was lower for Imipenem-treated patients than for patients receiving initially other selected antibiotic regimens. The savings are apparently due to a faster recovery of the patients resulting in reduced duration of therapy. The study shows that assessment of cost of therapy per day might be misleading in the economic analysis of antimicrobial chemotherapy.

Adolescent↗
PubMed1996

Characterization of indole-negative Bacteroides fragilis group species with use of polymerase chain reaction fingerprinting and resistance profiles.

Biochemical tests alone do not adequately differentiate the various Bacteroides species, groups, and antimicrobial-resistant variants. Consequently, we used a polymerase chain reaction (PCR) fingerprinting technique, with either a single nonspecific primer derived from the t-DNA intergenic spacer region (T3B) or a single primer that anneals to minisatellite DNA sequences (M13 core), to identify and characterize 58 clinical isolates of Bacteroides fragilis group species (B. fragilis, B. distasonis, and B. caccae). In addition to species- and subspecies-specific differences, 4 strains of B. fragilis, 1 of B. distasonis, and 3 of B. caccae that showed increased resistance to imipenem, ampicillin, and ampicillin/sulbactam also produced unique PCR fingerprint profiles. Analysis by the clinical source of isolation (i.e. blood or intraabdominal, skin, or soft-tissue infection) indicated that no particular PCR fingerprint type was associated with greater pathogenicity of any individual clinical source. The PCR fingerprinting technique proves to be a useful tool for species identification and taxonomic studies, as well as for epidemiological studies of Bacteroides species.

Bacterial Typing Techniques↗
PubMed1995

Identification and strain differentiation of 'Bacteroides fragilis group' species and Prevotella bivia by PCR fingerprinting.

Using single consensus primers of genomic nucleotide sequences, PCR-generated fingerprints were used for identification and differentiation of the Bacteroides fragilis group (B. fragilis, B. thetaiotaomicron, B. ovatus, B. distasonis, B. vulgatus) and Prevotella bivia (B. bivius) by comparing the DNA profiles with those of reference strains from the American Type Culture Collection and German Culture Collection. When primed by a single primer phage M13 core sequence, intra-species specific differences and species-specific bands were detected. Using primers derived from the evolutionarily conserved tRNA gene sequence, species-specific patterns were produced. A computer program, GelManager, was used to analyze the profiles and generate dendrograms. The correlation coefficients determined from the DNA fingerprint profiles of the clinical isolates (using the M13 core primer) fell within a narrow range, reflecting a high level of homology within the species. Based on the dendrograms, strains of one species were clearly differentiated from strains of other species. For comparison, SDS-PAGE analysis of whole cell extracts was also performed to obtain protein band patterns of various strains. Because of the simplicity of the PCR fingerprinting method and the ease of performance of computerized evaluation of data, this technique is a useful method for both species and strain differentiation, as well as for characterization of Bacteroides species and Prevotella bivia.

Journal Article↗
PubMed1995

Discrepancies in susceptibility test results for imipenem employing different in vitro test methods and DIN 58,940 breakpoints.

During the first half of 1993, bacteria that were isolated from clinical materials and found to have intermediate susceptibility by an agar dilution breakpoint method were collected in a large service laboratory in Germany. All of these isolates were gram-negative bacteria. They were re-tested employing full-scale agar dilution, broth microdilution, E-test and agar diffusion procedures. The results obtained indicated that 76.9% of the isolates were actually susceptible upon re-testing with a reference agar dilution technique. The reason for the discrepant results remained largely unclear. There was a high correlation between agar dilution and E-test results while the agreement with broth microdilution and agar diffusion was less satisfactory. It is suggested that the breakpoint between susceptible and intermediate categories currently recommended by DIN 58,940 (standard set by Deutsches Institut für Normung e.V.) be raised to reduce erroneous interpretations of minimum inhibitory concentrations.

Bacteriological Techniques↗
PubMed1993

[Possibilities for the use of basic cephalosporins].

The always growing number of cephalosporins constitutes a significant part of the betalactam antibiotics. Depending on antibacterial spectrum and in vitro activity, different groups, e.g. the "cefuroxime-group" and the "cefotaxime-group" have been defined. Based on epidemiologic and comparative in vitro data, the present review offers some guidance where the less expensive cephalosporins of the "cefuroxime-group" may still be clinically useful.

Bacteria↗
PubMed1992

German multicentre study on the in vitro susceptibility of Bacteroides species. The German Bacteroides Study Group.

In 1990 the first German multicentre study on the in vitro susceptibility of Bacteroides species was completed. Employing a commercially prepared microbroth dilution assay, nine participating institutions evaluated approximately 100 consecutive isolates of Bacteroides species from relevant clinical specimens. A total of 911 strains (449 Bacteroides fragilis, 201 Bacteroides thetaiotaomicron, 79 Bacteroides ovatus, 78 Bacteroides vulgatus, 77 Bacteroides distasonis, 25 Bacteroides uniformis, 2 others) were tested. Most of the isolates came from surgical patients (72%); other sources included gynaecological patients (9%) and medical patients (5%). Seventy-eight percent of the anaerobes were found in mixed culture together with at least one aerobic organism (Escherichia coli 36%, streptococci 15%, or enterococci 13%), while in 22% of the cases, the anaerobes were the only bacteria grown from the specimens. The results showed that many of the strains were potent beta-lactamase producers (as judged by resistance to amoxicillin). However, all but one of the isolates demonstrated susceptibility in vitro when clavulanic acid was added to amoxicillin or ticarcillin. At the same time, 13% of the organisms were resistant to mezlocillin, 5% to cefoxitin and 4% to clindamycin. Three strains were reported resistant to imipenem and one strain to metronidazole.

Anti-Bacterial Agents↗
PubMed1992

Overproduction of a penicillin-binding protein is not the only mechanism of penicillin resistance in Enterococcus faecium.

In 1989 and 1990, a large number of ampicillin-resistant strains of Enterococcus faecium were isolated from infected patients treated at intensive care units in Berlin, Germany. Twenty-five clinical isolates, including five different biotypes as classified by acid production from various sugars and a wide range of susceptibilities to ampicillin (MICs between 0.5 and 128 micrograms/ml), were selected for a detailed analysis of penicillin-binding proteins (PBPs). All strains contained a slowly reacting PBP with low penicillin affinity known to be present in enterococci. Overproduction of this PBP relative to susceptible isolates was noted, especially in all strains for which the MIC of ampicillin was 8 micrograms/ml, to a lesser degree in the more resistant strains, but not at all in the three highly resistant isolates for which the MIC was 128 micrograms/ml. In these three strains, this PBP appears to have a reduced affinity for beta-lactams. The results suggest that overproduction of PBP 6 correlates only with intermediate resistance levels and that higher resistance is mediated by yet another, still unknown mechanism, probably including reduction of beta-lactam affinity in one or more PBPs.

Bacterial Proteins↗
PubMed1991

[Bacteriologic findings before and in transcervical chorionic villi biopsy and their clinical relevance].

Between August 1987 and May 1989, bacteriological examinations of smears from the cervical canal was performed in 358 pregnant women, who underwent transcervical sampling of chorionic villi. The outcome of 349 of these pregnancies is documented. 12 of these patients (3.5%) had an artificial abortion for genetic reasons. In 12 other patients, the pregnancy ended before 28 weeks (one child surviving). Microbiological examinations showed that in 187 women (52%), it was possible to culture one or more microorganisms from the cervical canal. The most frequently detected pathogen was Chlamydia trachomatis (111 women, 31%). In pregnancies, where more than one microorganism could be cultured, the risk of following abortion was 8.9 times higher than in those, where no pathogens could be found. In only two of the 12 women with a subsequent spontaneous abortion (16.6%), no microorganism could be found. The bacterial contamination of the cervical canal during TC-CVS seems to be a risk factor for subsequent abortion. Therefore, a bacteriological examination of cervical flora should be performed before as well as during TC-CVS, and antibiotic therapy should be initiated in case of positive results.

Abortion, Septic↗
PubMed1990

Suppression of blastogenic transformation of lymphocytes by Bacteroides fragilis in vitro and in vivo.

Bacteroides species and Enterobacteriaceae are known to cause synergistic infections. However, the mechanisms behind this synergy are not completely understood. Several authors have shown that Bacteroides species may inhibit the phagocytosis of Enterobacteriaceae by polymorphonuclear leukocytes as well as by macrophages. With the present study we have addressed the question of whether Bacteroides fragilis (BF) is also capable of suppressing specific immune functions. When incubated together with murine lymphocytes, BF significantly inhibited the blastogenic transformation of these cells stimulated by Escherichia coli-lipopolysaccharide (LPS) or concanavalin A. This effect was dose dependent and was not mediated by prostaglandins. Other bacteria such as E. coli or Listeria monocytogenes did not show such an extensive suppression, while Streptococcus pneumoniae was equally active. BF also inhibited the pokeweed mitogen induced blastogenic transformation of human lymphocytes. Moreover, lymphocytes from BF-injected animals obtained 3 to 12 hours after infection proved to be partly refractory for LPS-stimulation. Finally, BF injections also affected T-cell dependent immunity as judged from the aggravation of an experimental listeriosis in mice.

Animals↗
PubMed1988

Effects of Staphylococcus epidermidis on cellular immunity to infection with Listeria monocytogenes.

With the present study, the effects of intravenous applications of Staphylococcus epidermidis (SE) on the course of experimental infections of mice with Listeria monocytogenes were evaluated. SE treatment 24 h prior to Listeria infection led to a reduced growth of Listeria organisms in both livers and spleens and to an increased resistance of infected animals against a lethal Listeria challenge. SE treatment 24 h after Listeria infection resulted in an enhanced growth of and retarded elimination of Listeria organisms from animal organs as well as in a reduction of delayed-type hypersensitivity to soluble Listeria antigen. Adoptive immunotherapy accomplished by transferring immune peritoneal exudate T-lymphocyte-enriched cells (PETLEs) to Listeria-infected recipients 24 h before SE treatment did not prevent the delay in clearance of Listeria organisms. When Listeria-infected recipients compromised in their immune response by SE treatment were infused with immune PETLEs either immediately or 24 h after the application of SE, the immunosuppression induced by SE proved to be reversible. It is concluded that, in analogy to other bacterial immunomodulators, Staphylococcus epidermidis is able to either nonspecifically activate macrophages or interfere with T-lymphocyte functions.

Animals↗
PubMed1986

Effects of anti-Bacteroides-antibodies on Escherichia coli and different Bacteroides species in vitro and vivo.

Bacteroides species are known to cause synergistic pathogenicity in mixed infections with Enterobacteriaceae. In vitro studies showed that anaerobes may compete with aerobes for opsonisation thus interfering with the phagocytosis and killing of the latter by leukocytes. The present study investigated the effect of anti-Bacteroides-antibodies on in vitro phagocytosis of E. coli and on experimental mixed infections. It was shown that in vitro, B. fragilis suppressed the phagocytosis of E. coli by leukocytes only moderately. The addition of specific antibodies to the phagocytosis mixture could enhance this effect. However, antibodies in the absence of B. fragilis were also active suggesting a nonspecific mechanism such as blockade of Fc receptors. Prophylactic treatment with the immunoglobulin preparations failed to protect mice from experimental infections with E. coli and Bacteroides species.

Animals↗
PubMed1986

Inhibition of macrophage phagocytosis by Bacteroides fragilis in vivo and in vitro.

A number of investigators have provided experimental evidence for synergistic effects in mixed infections with Escherichia coli and Bacteroides fragilis. In vitro studies have suggested that competition for serum opsonins and diminished subsequent phagocytosis by polymorphonuclear leukocytes might explain these effects. In the present study we evaluated the effect of B. fragilis on macrophage phagocytosis. It was shown that peritoneal macrophages from mice injected intravenously 6 to 12 h earlier with 10(8) CFU of encapsulated B. fragilis were markedly suppressed in their phagocytic ability. Injections of laboratory-passaged, less-encapsulated B. fragilis, other bacteria, or latex particles were either not suppressive of macrophage phagocytosis or less effective. When peritoneal macrophages were treated in vitro for 24 h with the same challenge organisms prior to assessing their phagocytic capacity, encapsulated B. fragilis also proved significantly more suppressive than challenges with other organisms or latex particles. We conclude that suppression of macrophage phagocytosis by B. fragilis seems to be an important mechanism contributing to synergistic effects described for mixed aerobic and anaerobic infections.

Animals↗