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A C Rodloff

Publications and source records attributed to A C Rodloff.

16 recordsLinked to original sources
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↗
PubMed1984

Synergistic lethality in experimental infections with Escherichia coli and Bacteroides fragilis.

Using an animal model, a synergism in lethality of infections with Escherichia coli and Bacteroides fragilis is described. This synergism was dependent on certain dosage combinations of the infectious agents. It was demonstrated that animal-passaged, laboratory-passaged, and heat-killed B. fragilis alike were capable of producing this synergism. However, animal-passaged B. fragilis showed superior recovery rates from animal organs.

Animals↗
PubMed1983

Intravenous injection of mice with bacteroides fragilis and Escherichia coli: role of Thioglycollate medium in the infectious process.

Mice were intravenously infected with E. coli, B. fragilis, and combinations of both, and the bacterial contents of livers, kidneys, and spleens were monitored from the first up to the 9th day postinfection. If Thioglycollate medium was added to otherwise sublethal doses of E. coli, the inoculum was able to induce severe and for some animals lethal infections. B. fragilis was not capable to produce prolonged infections; however, when given together with E. coli and Thioglycollate medium, both bacteria were recovered from some animal organs even on day 9 postinfection. Employing this experimental model of a mixed anaerobic/facultative bacterial infection, previous reports attributing animal lethality to E. coli were confirmed, but a synergism between E. coli and B. fragilis could not be demonstrated.

Animals↗
PubMedDate not supplied

Combined activity of trospectomycin and colloidal bismuth subcitrate against Helicobacter pylori in vitro.

The combined activities of trospectomycin, a spectinomycin analogue, and colloidal bismuth subcitrate against Helicobacter pylori were investigated, the agar dilution method being employed. Forty-seven strains of H. pylori were examined. An additive effect was observed in 89%, and a synergistic interaction in 11% of the isolates. There was no antagonism observed. The MIC50 of trospectomycin against H. pylori was 2 mg/l; the MIC ranged from 0.5 to 4 mg/l.

Antacids↗
PubMedDate not supplied

Induction of an atypical interferon by bacteroides fragilis and Escherichia coli in experimental infections and in leukocyte cultures.

Previous reports have shown that Bacteroides fragilis may enhance the pathogenicity of coinfecting enterobacteriaceae by interfering with the host's immune response. With the present study, we have investigated the possible role of interferons (IFN) in mediating these effects. Mice injected with B. fragilis developed moderate serum levels of IFN that appeared just prior to alterations of the animals' immunity described earlier. The IFN was neutralized by treatment with anti-IFN-alpha/beta-antibodies or hydrochloric acid; hence it displayed the same "atypical" characteristics as IFN found in patients with immuno-compromising diseases such as AIDS, systemic lupus erythematosus or rheumatoid arthritis. Escherichia coli displayed the same induction patterns as B. fragilis, while gram-positive bacteria induced "regular" IFN alpha/beta and gamma. Spleen cells, peritoneal macrophages, or liver leukocytes taken from B. fragilis or E. coli-injected animals 6 h post infection were refractory to IFN induction by E. coli lipopolysaccharide in vitro; cells from mice infected with gram-positive organisms showed normal or enhanced responsiveness.

Animals↗
PubMedDate not supplied

Identification and susceptibility patterns of anaerobic bacteria isolated from clinical specimens during a one-year period.

During the whole of 1983, all anaerobes cultured from clinical specimens were identified using both the Minitek system and gas chromatography. Antimicrobial susceptibility patterns were established using a broth microdilution test. The results show isolation rates for the individual species to be in good agreement with previous studies. Despite widespread use (even for prophylactic purposes), mezlocillin, latamoxef, cefoxitin, metronidazole and clindamycin retained their high activity against anaerobic bacteria and no clusters of resistance were observed. Augmentan also showed excellent in vitro activity. Penicillin was found to be inactive against most gram-negative anaerobic rods while tetracycline showed a rather high degree of resistance.

Anti-Bacterial Agents↗