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Biomedical subjects

K Dornbusch

Publications and source records attributed to K Dornbusch.

At least 73 records · Page 4Linked to original sources
PubMed1979

Factors contributing to resistance to beta-lactam antibiotics in Bacteroides fragilis.

Fifteen strains of Bacteroides fragilis, five highly resistant, five moderately resistant, and five susceptible to benzylpenicillin and cephaloridine, were tested for beta-lactamase production. In the highly resistant and the moderately resistant groups of strains, a correlation between formation of beta-lactamase and minimal inhibitory concentrations was demonstrated. In the presence of the beta-lactamase inhibitors clavulanic acid and CP-45,899 at concentrations of 1 mug/ml, the susceptibility to cephaloridine increased fourfold or more in the beta-lactamase-producing strains. Crypticity measurements (beta-lactamase activity broken/intact cells) with cephaloridine as substrate could indicate a diffusion barrier in the cell wall.

Anti-Bacterial Agents↗
PubMed1979

Bacteriuria diagnosis and antibiotic susceptibility testing in a group practice by dipslide techniques.

In group practice, screening for bacteriuria and antibacterial susceptibility testing of bacteria in urine specimens were performed by dipslide methods (Uricult and Sensicult, Orion Diagnostica) and the results were evaluated with respect to conventional cultivation of urine specimens and standardized susceptibility testing by the disc diffusion method at a bacteriological laboratory. Bacteriuria diagnosis by screening by the Uricult method seemed to be satisfactorily performed except for some streptococcal strains. In the case of direct susceptibility testing by the Sensicult dipslide method, however, the results obtained by personnel at the surgeries and by trained bacteriologists displayed unacceptable disparities, despite the fact that a continuously running training programme was established.

Anti-Bacterial Agents↗
PubMed1979

Antibiotic susceptibility of anaerobic bacteria with special reference to Bacteroides fragilis.

It was shown that recent Swedish clinical isolates of anaerobic bacteria are susceptible to many antibiotics by the agar dilution method with the exception of the Bacteroides group versus beta-lactam antibiotics or tetracyclines. Strains of B. fragilis were inhibited by 4--greater than 128 micrograms benzylpenicillin or cephalothin/ml, 1.0--64 micrograms cefoxitin/ml, 0.064--2 micrograms clindamycin or metronidazole/ml, 2--8 micrograms chloramphenicol/ml, 2--16 micrograms fusidic acid/ml and 0.032--32 micrograms doxycycline/ml. Resistance to beta-lactam antibiotics was partly due to the production of beta-lactamase. Growth of beta-lactamase producing strains in the presence of enzyme inhibitors such as clavulanic acid or CP-45899 together with cephaloridine lowered the MIC's manyfold. Cefoxitin with relative resistance to beta-lactamases inhibited the majority of the strains at 8 micrograms/ml. Cefoxitin-resistant strains (MIC greater than or equal to 16 micrograms/ml) were also resistant to the new cephalosporins BL-S786 and HR-756 as well as to the new cefamycins A, B, CL619-183, CS-1170 and Sq-14359 and to thienamycin. Cefamycin CL619-183, only showed a slightly higher in vitro activity than cefoxitin. Resistance to the cefamycins could not be correlated to the production of beta-lactamases.

Anti-Bacterial Agents↗
PubMed1978

Evaluation of microdilution trays (sensititre) for antimicrobial susceptibility testing of Bacteroides fragilis.

Microdilution trays (Sensititre) for antimicrobial susceptibility testing of Bacteroides fragilis has been compared for accuracy with the standard agar dilution method. The microtrays were found to be reliable for all antimicrobials tested (benzylpenicillin, clindamycin, doxycycline, chloramphenicol, fusidic acid, cefoxitin, and cephalotin) but not for metronidazole.

Anti-Bacterial Agents↗
PubMed1978

Concentrations of azidocillin, erythromycin, doxycycline and clindamycin in human mandibular bone.

Postoperative complications after surgery in the mandible are still a clinical problem. Levels of four antibiotics--azidocillin, erythromycin, doxycycline and clindamycin--were measured in serum, dental alveolar serum, saliva and mandibular bone in 24 patients undergoing surgical removal of mandibular third molars. The concentration in mandibular bone for azidocillin was 0.8 microgram/g +/- 0.4 microgram/g, erythromycin 0.2 microgram/g +/- 0.1 microgram/g, doxycycline 2.6 microgram/g +/- 2 microgram/g and clindamycin 0.6 microgram/g +/- 0.4 microgram/g. No saliva levels were achieved with azidocillin and erythromycin, whereas doxycycline and clindamycin gave measurable saliva levels.

Adolescent↗
PubMed1978

Antibiotics in bone tissues. Methodological and practical aspects.

With regard to determination of antibiotic levels in bone, variance in results may be obtained as a consequence of type of the bones involved, degree of penetration of the drug used and of assay method performed. Measurements of antibacterial activity in bone from patients undergoing orthopaedic surgery were performed after preoperative treatment with doxycycline, lincomycin, clindamycin or cefuroxime. In performing the assay by the agar diffusion method, after extraction of the bone specimens in buffer according to classical systems, the concentrations of doxycyline were in the range of 0.05--0.6 microgram/g, clindamycin 0.4--4.9 microgram/g, lincomycin 1.7--2.9 microgram/g and of cefuroxine about 0.4 microgram/g. After electrophoresis in agarose-gel and followed by microbiological assay higher levels of these drugs were estimated possibly as a consequence of a diminution in the binding capacity of bone.

Anti-Bacterial Agents↗
PubMed1978

beta-lactamases in bacteroides.

Bacteroides fragilis is responsible for most anaerobic infections in man. Most isolates of B. fragilis show resistance to beta-lactam antibiotics. This resistance might be due to beta-lactamase production or permeability barrier in the cell wall. B. fragilis produce beta-lactamase with mainly cephalosporinase activity. Other Bacteroides species such as B. clostridiformis, B. melaninogenicus and B. oralis also produce beta-lactamase but with different biochemical characteristics.

Amidohydrolases↗
PubMed1978

beta-lactamase production by strains of Escherichia coli of intermediate susceptibility to beta-lactam antibiotics. A study of their clinical significance in urinary tract infection.

In a prospective study of patients treated with cephalexin or co-trimoxazole, almost all isolated E. coli strains of intermediate susceptibility to ampicillin or cephalosporin (MIC 2-16 microgram/ml) were shown to produce beta-lactamase detectable with a chromogenic cephalosporin substrate, or by the clover-leaf test or the acidimetric method. When assayed in preparations of sonicated bacteria, the enzyme had a cephalosporinase-substrate profile in a large majority of cases. In order to evaluate the clinical significance of this beta-lactamase production, 48 patients with urinary tract infection (UTI) were treated with cephalexin, an antibiotic hydrolysed by the enzyme. Forty-three additional patients were treated with co-trimoxazole for comparison. A statistically significant difference in cure rate (p less than 0.05) was found after 2 weeks. Six recurrences occurred in the cephalexin group and none in the co-trimoxazole group. However, after six weeks there were 8 and 5 recurrences, respectively (p less than 0.05). There were no differences in beta-lactamase activity or MIC/MBC between initial strains and isolates from recurrent UTI. Thus, the recurrent infections were not due to emergence of resistance.

Adolescent↗
PubMed1977

Susceptibility to beta-lactam antibiotics and production of beta-lactamase in Bacteroides fragilis.

Using the agar dilution technique, 231 strains of Bacteroides fragilis, isolated during a 2-year period from human infections, were identified at subspecies level and were tested for susceptibility to 13 beta-lactam antibiotics. The penicillins were benzylpenicillin, ampicillin, carbenicillin, cloxacillin, and the recently described penicillin derivatives cyclacillin, ticarcillin, and PC-904. The following cephalosporin derivatives were tested: cephaloridine, cephalothin, cephalexin, cefamandole and cefuroxime. The cephamycin C derivative cefoxitin was also included in the study. Cefoxitin was the most effective drug tested since more than 80% of the strains were inhibited by 8 microgram/ml or less, and no strain had a minimal inhibitory concentration (MIC) of more than 64 microgram/ml. There was no marked difference in sensitivity among the subspecies with exception of subspecies vulgatus, which was slightly more sensitive to all antibiotics tested. The size of the inoculum was an important factor for obtaining reproducible results in the sensitivity tests. Increased inocula resulted in markedly higher MICs for cephaloridine and cefuroxime. Production of beta-lactamase was performed on all isolates by a chromogenic cephalosporin substrate and about 90% of the strains were found to be beta-lactamase producers.

Amidohydrolases↗
PubMed1977

Antimicrobial in vitro susceptibility of actinomyces israelii and arachnia propionica.

46 reference strains and clinical isolated of Actinomyces israelli and 8 strains of Arachnia propionica--the causative microorganisms of actinomycosis in man--were tested for their in vitro susceptibility to penicillin, sulfaisodimidine, erythromycin, tetracycline, lincomycin, clindamycin, metronidazole and tinidazole by the agar dilution method. All strains were susceptible to benzylpenicillin (minimum inhibitory concentrations, MICs of less than or equal to 0.064 mug/ml). Many strains were resistant in vitro to sulfaisodimidine (MICs 4.0-32.0 mug/ml). Erythromycin, tetracycline, clindiamycin and lincomycin possessed in vitro activity at concentrations readily attainable in serum. Due to adverse side-effects associated with clindamycin and lincomycin therapy, erythromycin and tetracycline may be the best alternative drugs to penicillin in the treatment of actinomycosis. In contrast, in vitro resistance (MICs greater than or equal to 4.0 mug/ml) of the pathogenic actinomycetes to metronidazole and tinidazole implies that these drugs may not be valuable in the therapy of human actinomycosis.

Actinomyces↗
PubMed1977

Use of electrophoresis in the identification and quantitation of antibiotics administered in combinations.

The investigation presents a method of electrophoretic separation of antibacterial drugs which are used in combinations in clinical medicine. Subsequent to electrophoresis in agarose gel, a microbiological assay was performed. This technique permitted the determination of the concentrations of beta-lactam antibiotics, rifampicin, and clindamycin in the presence of aminoglycosides. In therapeutic combinations of fusidic acid and clindamycin, the concentrations of each drug could be determined.

Aminoglycosides↗
PubMed1977

Studies on the clinical efficacy, serum levels and side effects of clindamycin phosphate administered intravenously.

Clindamycin phosphate was administered intravenously to 41 patients with different types of infections including osteomyelitis, septicaemia and soft tissue infections. All bacterial strains tested showed low MIC values for clindamycin. Maximum serum concentrations after 600 mg intravenously were 6.0--29.0 microgram/ml, after 300 mg intravenously 2.6--26.0 microgram/ml. The therapeutic effect of the drug was considered good in 26 of 31 patients with proven or probable bacterial aetiology. Side effects were noted in 16 of the 41 patients. However, in only 5 of these the treatment had to be terminated, all due to pruritic rashes. In the 7 cases with diarrhoea as side effect, the symptoms were mild and of short duration.

Adult↗
PubMed1977

Assay of gentamicin concentrations in serum specimens by microbiological and radioenzymatic methods.

Assay of gentamicin concentrations were performed on 167 patient sera by two methods in the routine work. A radioenzymatic method that measures the acetylation of getamicin by a bacterial enzyme extract and the overnight agar diffusion method, using cups as diffusion centres, were used. The methods correlated well (r = 0.87), although the results of the microbiological assay in some cases were higher than the results of the enzymatic assay. When artificial samples were tested the microbiological methods gave variable results. Therefore careful standardization is necessary for accuracy and reproducibility. The enzymatic assay, however, offered advantages of specificity, reproducibility and rapidity.

Acetylation↗
PubMed1977

Occurrence and transfer of ampicillin resistance associated with ampicillin-resistant Haemophilus influenzae isolated from a case at a day-care centre.

A 1-year-old boy with recurrent otitis media had been repeatedly treated with antibiotics. A few days after withdrawal of administered ampicillin he again contracted otitis media and ampicillin-resistant Haemophilus influenzae was isolated. The strain was serologically untypable. No ampicillin-resistant H. influenzae was found in his family or at the day-care centre that he attended. The ability to produce the beta-lactamase elaborated from this strain could be transferred to ampicillin-sensitive strains of H. influenzae and Escherichia coli in frequencies of 0.7 X 10(-7) and 4.1 X 10(-4) respectively. The transcipients obtained were ampicillin-resistant and beta-lactamase producing. In the transcipients of E. coli, however, the marker for ampicillin resistance was quite unstable.

Amidohydrolases↗
PubMed1976

Some properties of coagulase-negative deoxyribonuclease-producing strains of staphylococci from human infections.

Twenty-seven coagulase-negative and deoxyribonuclease-positive staphylococci were isolated from more than 3000 specimens from human infections. The strains were tested by conventional biochemical tests and by simple agar plate assays for production of different extracellular enzymes and toxins. Three strains were lysed by S. epidermidis phages and 7 strains by S. aureus phages. All strains produced thermolabile nuclease but only 21 strains produced thermostable nuclease. The investigated strains belonged to a heterogeneous intermediate group sharing characters of S. aureus and S. epidermidis. Tests for production of coagulase and thermostable nuclease should be used in the classification of these intermediate strains in diagnostic bacteriology.

Bacteriophage Typing↗