Biomedical subjects

S C Edberg

Publications and source records attributed to S C Edberg.

At least 73 records · Page 4Linked to original sources

PubMed1985

An animal model of Curvularia geniculata and its relationship with human disease.

The conidiospore of Curvularia geniculata was observed in the bronchial washings of a patient who subsequently developed pulmonary aspergillosis. Curvularia geniculata was grown in culture and used in experiments in mice to explore its possible role as a disease causing agent. The fungus, after intraperitoneal injection, produced granulomas in the liver and spleen. Studies on the pathogenicity of this fungus in mice produced similar lesions to those observed in the human case. A comparison of the lesions in the patient's lung and in the animal experimental model is presented.

Adult↗

PubMed1985

Assay of extracellular proteinases using a colorimetric collagen substrate for the differentiation of Serratia in the tribe Klebsielleae.

The gelatin test has been utilized for many years as a characteristic to separate the genus Serratia from other members of the tribe Klebsielleae. Gelatin is a large protein matrix that cannot diffuse into bacterial cells. Microbes that attack gelatin do so by producing extracellular proteinases. The measurement of gelatinase has suffered from the lack of a definable endpoint and the inability to quantitate the enzyme. A method was developed utilizing an azo-dye-labelled collagen substrate that could measure the extracellular proteinase of serratia. The test was easy to perform, inexpensive, and potentially quantifiable. The azo-dye test corresponded completely with the gelatinase tests.

Collagen↗

PubMed1985

Measurement of active constitutive beta-D-glucosidase (esculinase) in the presence of sodium desoxycholate.

The hydrolysis of esculin in the presence of bile has been utilized for many years for the identification of bacteria. It is especially useful in differentiating species of the genus Streptococcus. The procedure is a two-step one. First, the bacterium must grow in a particular concentration of bile, and second, it must hydrolyze esculin. The hydrolysis of esculin has traditionally been determined by the brown-black color that results when one of the hydrolysate products, esculetin, reacts with iron in the medium. The procedure requires incubation for 24 h or more. A method was developed based on the measurement of constitutive beta-glucosidase (esculinase) with the repression of this enzyme by bile equivalent (sodium desoxycholate) that required only 30 min. p-Nitrophenyl-beta-D-glucopyranoside was the esculinase substrate, and sodium desoxycholate was substituted for bile salts. After inoculation, a yellow color was equivalent to the brown-black seen in the 40% bile-esculin reaction. The reagent was dispensed in test tubes and was stable for 6 months. The 30-min procedure correlated well with the conventional 24-h bile-esculin agar tube. Streptococcus pneumoniae could also be identified because of the rapid lysis it exhibited in the substrate solution.

Bacteria↗

PubMed1985

Lack of constitutive beta-glucosidase (esculinase) in the genus Fusobacterium.

Esculin has been incorporated into both a medium and test with 20% bile for many years to differentiate Bacteroides from Fusobacterium organisms. After 24 to 48 h, all members of the Bacteroides fragilis group grow in 20% bile and hydrolyze esculin. Fusobacterium mortiferum can both grow in bile and hydrolyze esculin, thus limiting the use of the bile-esculin medium and test. The hypothesis that constitutive esculinase (beta-glucosidase) could differentiate Bacteroides from Fusobacterium organisms was investigated. Clinical isolates and American Type Culture Collection clones of the B. fragilis group and other species of Bacteroides and Fusobacterium were tested. All B. fragilis were positive within 30 min. In no case was a Fusobacterium organism positive for constitutive enzyme in a hydrolyzable substrate-based test. The percentage of positive results for other species of Bacteroides agreed with those published in the literature for the esculin test. The genus Fusobacterium can be separated from Bacteroides organisms based on a lack of constitutive beta-glucosidase in the former in a 30-min one-tube test.

Bacteroides↗

PubMed1984

Corynebacterium diphtheriae endocarditis: sustained potential of a classical pathogen.

This communication concerns a case of endocarditis caused by Corynebacterium diphtheriae. The patient was a 35-year-old male drug addict who was brought to the hospital with fever, chills, and abdominal pain. Two days after admission, blood cultures were found to be growing gram-positive rods suggestive of diphtheroids. Repeated blood cultures grew the same organism, which was identified as a nontoxigenic strain of C. diphtheriae. The patient subsequently was identified as having acquired immune deficiency syndrome. Although isolates are divided into toxigenic and nontoxigenic strains, all isolates of C. diphtheriae should be considered potentially toxigenic. Because diphtheria generally is considered only of historic interest, few laboratories perform tests to identify it and instead report all isolates as "diphtheroids" or Corynebacterium. Because all isolates are potentially toxigenic, and because there is a large reservoir of nonimmunized people, laboratories must be alert to possible serious epidemiologic situations.

Acquired Immunodeficiency Syndrome↗

PubMed1984

Measurement of microbial alpha-amylases with p-nitrophenyl glycosides as the substrate complex.

The detection of alpha-amylase is commonly used in clinical microbiology laboratories to aid in differentiating Streptococcus bovis from other streptococci. It is also useful in identifying Eikenella corrodens and the gravis subspecies of Corynebacterium diphtheriae and in separating species of the genera Bacteroides, Clostridium, Actinomyces, and Bacillus. Currently, the most frequently used procedure utilizes starch as the substrate and iodine as the indicator. Starch is incorporated into a agar medium, the isolate is inoculated on the surface, and the medium is incubated for 24 to 48 h. A 15-min test containing p-nitrophenyl polyglycosides as the substrate complex was developed to yield results comparable with the agar-based starch test. The reagent was made in liquid form, 0.20 ml per tube, and could be incubated either in ambient air or at 35 degrees C. When dried, the p-nitrophenyl polyglycoside reagent could be stored at 0 degrees C for 4 weeks.

Bacteria↗

PubMed1984

Methylumbelliferyl-beta-D-glucuronide-based medium for rapid isolation and identification of Escherichia coli.

Escherichia coli is the most common gram-negative microbe isolated and identified in clinical microbiology laboratories. It can be identified within 1 h by oxidase, indole, lactose, and beta-glucuronidase tests. The oxidase and indole tests are performed as spot tests, and lactose fermentation is read directly from MacConkey agar. It was found that 4-methylumbelliferyl-beta-D-glucuronide could be incorporated directly into a modified MacConkey agar to directly detect the presence of beta-glucuronidase. Other characteristics of MacConkey agar were not affected. The incorporation of 4-methylumbelliferyl-beta-D-glucuronide into modified agar obviated the need for manufacture, quality control, and incubation of reagent-containing test tubes. The time needed to identify E. coli strains was reduced from 1 h to 5 min, and the ability to detect this species in mixed specimens was also enhanced.

Agar↗

PubMed1984

Differentiation of Neisseria gonorrhoeae from other Neisseria species by use of the restriction endonuclease HaeIII.

We used the restriction endonuclease HaeIII to differentiate Neisseria gonorrhoeae from other Neisseria species and Branhamella catarrhalis. A total of 16 clinical isolates and four American Type Culture Collection strains of N. gonorrhoeae were resistant to HaeIII digestion, whereas 17 isolates and four American Type Culture Collection strains from eight different bacterial species were susceptible. This resistance was not caused by an enzyme inhibitor. We propose that protection of the HaeIII recognition sequence by methylation is the mechanism of resistance since N. gonorrhoeae DNA became susceptible to digestion when passed in Escherichia coli as part of a plasmid clone.

Base Sequence↗

PubMed1984

In vitro susceptibility of Streptococcus bovis to six antibiotics.

A recent report of two isolates of Streptococcus bovis resistant to killing by low levels of penicillin G prompted this study of the in vitro susceptibility of 100 clinical isolates of S bovis to six antibiotics. Using a microdilution method, we found the minimum bactericidal concentrations for 99% of the isolates to be as follows: penicillin G, 0.5 microgram/ml; methicillin, 16 micrograms/ml; ampicillin, 0.5 microgram/ml; cephalothin, 2 micrograms/ml; clindamycin, 2 micrograms/ml; and vancomycin, 2 micrograms/ml. The high-level resistance of S bovis to penicillin G previously described was not seen. This study suggests that penicillin G can still prove effective in treating most infections caused by S bovis, including infective endocarditis, and that cephalothin and vancomycin are useful alternative agents.

Ampicillin↗

PubMed1983

Inactivation of the polyanionic detergent sodium polyanetholsulfonate by hemoglobin.

Sodium polyanetholsulfonate (SPS) has been added to blood culture media for many years. Its incorporation results in a higher yield of positive blood cultures due to its inactivation of antimicrobial cationic compounds. The most active of these cations include complement components, aminoglycoside-aminocyclitol antibiotics, and receptors on polymorphonuclear leukocytes. There have been reports from studies conducted outside patient blood culture bottles that SPS itself may possess antibacterial activity against some isolates of Neisseria meningitidis, Neisseria gonorrhoeae, and Peptostreptococcus anaerobius. Conversely, in patient clinical trials there has been no significant difference in pathogen isolation rates in the presence or absence of SPS. In an attempt to explain this in vitro/in vivo disparity, a search was undertaken to elucidate which variable constituent in blood, heretofore not studied quantitatively, might have a major effect on modulating the activity of SPS. It was found that hemoglobin combined stoichiometrically with SPS with a Kd of approximately 10(-7) mol/liter. Optimum SPS inactivation occurred at an SPS/hemoglobin ratio of 1:6 (wt/wt). SPS-sensitive isolates of N. gonorrhoeae and N. meningitidis were protected by the addition of hemoglobin from the antimicrobial effects of this polyanion in time-kill studies. This protection was directly related to the amount of SPS combined in solution. Therefore, the amount of free hemoglobin in solution must be measured when studying the antimicrobial activity of polyanions or when evaluating the effect of different polyanions on the recovery rates of pathogens in patient blood culture clinical trials.

Bacteriological Techniques↗

PubMed1983

Rapid and economical identification and antimicrobial susceptibility test methodology for urinary tract pathogens.

To decrease the time and cost of processing urine cultures, we devised a critical pathway to identify and perform antibiotic susceptibility tests on commonly isolated microbial pathogens within 6 h of growth detection. The strategy was based on eliminating expensive kits and automated procedures when not required. A pathway utilizing a statistical matrix and three rapid biochemical tests required to identify the most common pathogen, Escherichia coli, was developed. This species, which represented 82% of urinary isolates, was identified in 1 h for less than 10% the cost of a commercial kit. The specificity of the 1-h E. coli identification battery was greater than or equal to 99.9% with a sensitivity of 93%. In addition, this critical pathway, adapting published methods, permitted the identification of other enteric pathogens, the group D streptococci, and Pseudomonas aeruginosa within 4 to 6 h. Furthermore, it accounted for other microbes that required longer periods of incubation. The pathway also included a rapid disk diffusion sensitivity test. Utilizing the critical pathway strategy, 76% (E. coli frequency of 0.82 X E. coli sensitivity of 0.93) of all urinary pathogens were identified within 1 h, and 98% were identified within 4 h with an antibiotic sensitivity test available within 6 h after the observation of growth. Costs were reduced from 2.5 to 5.0 times. This methodology is applicable to other specimen types.

Anti-Bacterial Agents↗

PubMed1982

Comparison of carriage rates of group B streptococcus in diabetic and nondiabetic persons.

In several published studies, diabetic persons appeared to be at increased risk for Group B streptococcal disease. Since colonization with pathogens frequently antedates disease, the authors studied the carriage rate of Group B streptococcus in 38 diabetic and in 39 nondiabetic age- and sex-matched subjects. Fifty-four per cent of the controls and 34% of the diabetics carried Group B streptococci in at least one of five sites cultured (p less than 0.05). The data indicate that an increased carriage rate of Group B streptococci cannot be invoked as a reason for the increased numbers of diabetic persons among patients with Group B streptococcal infections.

Adult↗

PubMed1981

A DL-DOPA drop test for the identification of Cryptococcus neoformans.

A simple melanin assay using DL.DOPA as the substrate was developed to aid in the identification of Cryptococcus neoformans. The DL-DOPA drop test was simple and efficient. The best results (100% of the C. neoformans isolates were positive) occurred when C. neoformans was grown for two days at room temperature on Sabouraud agar modified. One to three loopfuls of yeast cells were then transferred to a starvation medium for 18-24 hours. Two of three drops of 0.3% DL-DOPA solution was applied to the transferred yeast cells. Only C. neoformans produced a brown or blackgrey pigment within 24 hrs, with 85% of the isolates becoming brown or black-grey within thirty minutes.

Cryptococcus↗

PubMed1981

Methods of quantitative microbiological analyses that support the diagnosis, treatment, and prognosis of human infection.

The microorganisms responsible for the production of an infection may be considered to be in two classes: classical microbes and host-defined microbes. Classical microbes are those pathogens which fulfill the Koch-Henle postulates, and their isolation from a host indicates infection. They are not normally part of the body's normal flora, although they may be acquired by the host and enter into a passive relationship known as the carrier state. Examples of this type of microbe are Bacillus anthracis (anthrax), Yersinia pestis (plague), and Bordetella pertussis (whooping cough). Pathogens that require specific hosts have largely replaced the classical pathogen as a cause of infection in hospitalized patients. Especially in recent years, with the advent of new modes of anticancer treatment and the general ability of the medical community to extent a patient's life span by chemotherapy and innovative surgery, the contribution to morbidity and mortality by microbes has substantially increased. These host-specific pathogens are largely part of the body's normal flora. It is incumbent upon the clinical microbiologist to be able to distinguish the patient's normal microbial load, an increased load due to physiological factors, but not representing infection, and a significant change from normal which should be considered infection. The ability to distinguish infection from noninfection is one of the prime responsibilities of the clinical microbiology laboratory and has contributed to the development of the infectious disease subspecialty of internal medicine. This article will examine a critical question: Is there a relationship between the numbers of microorganisms isolated from a specimen and the production of infection, and, if so, does this relationship vary for the different anatomical sites of the body?

Animals↗

PubMed1980

Turbidimetric determination of blood aminoglycoside levels by growth curve analysis.

A procedure to assay rapidly blood aminoglycoside levels was developed based on growth curve analysis of continuous absorbance measurements of a bacterial test strain. Of the means available for monitoring bacterial growth quantitatively, turbidimetric measurement was selected because it can be used to perform a clinical assay in less than 4 hr. Continuous turbidimetric measurements provide information as soon as the antimicrobial agent affects growth, which often occurs within 60 min of the start of an assay. Several bacterial isolates were evaluated before Staphylococcus aureus (MHMC 386) was chosen as the test microorganism. This isolate was quite sensitive to the aminoglycoside antibiotics, permitted the rapid measurement of blood levels of amikacin, gentamicin, kanamycin, and tobramycin, and exhibited a linear dose-response relationship of turbidity over a wide range of antibiotic concentrations.

Aminoglycosides↗

PubMed1980

Gentamicin uptake in wild-type and aminoglycoside-resistant small-colony mutants of Staphylococcus aureus.

Gentamicin uptake and killing were studied in aminoglycoside-susceptible wild-type Staphylococcus aureus strains and aminoglycoside-resistant small-colony mutants selected by gentamicin from these strains. In wild-type S. aureus three phases of gentamicin accumulation were noted, and killing occurred during the last and most rapid phase of uptake. Uptake and killing were abolished by anaerobic growth and sodium azide, suggesting that energy-dependent active drug transport required respiration. Treatment of wild-type strains with the uncouplers N,N'-dicyclohexyl carbodiimide (DCCD) and carbonyl cyanide-m-chlorophenyl hydrazone showed disparate effects on gentamicin uptake, producing enhanced and diminished accumulations, respectively. Small-colony mutants demonstrated markedly deficient uptake compared with the wild-type strains and were not killed by gentamicin in concentrations up to 10 mug/ml. Several classes of aminoglycoside-resistant mutant strains are described. One mutant strain was a menadione auxotroph which, when grown in the presence of menadione, exhibited normal gentamicin uptake and killing. Gentamicin uptake and killing in this strain were abolished by KCN when the strain was grown in a medium supplemented with menadione. The membrane adenosine triphosphatase inhibitor DCCD was lethal for this mutant but not for other mutants or wild-type strains. Preincubation with menadione prevented the lethal effect of DCCD, and this strain demonstrated normal gentamicin accumulation when exposed to both DCCD and menadione. A second mutant strain demonstrated both gentamicin uptake and killing in the presence but not the absence of DCCD. Studies with small-colony mutants of S. aureus indicated that the defect in aminoglycoside uptake is very likely related to an inability to generate or maintain energized membranes from respiration. These studies suggest that the membrane energization associated with active aminoglycoside accumulation requires electron transport for the generation of a protonmotive force.

Aminoglycosides↗

PubMed1980

Rapid biochemical characterization of Haemophilus species by using the micro-ID.

Biotyping of Haemophilus influenzae into five type and H. parainfluenzae into three types based on indole production, ornithine decarboxylase, and urease has been reported (M. Kilian, Acta Pathol. Microbiol. Scand. Sect. B 82:835--842, 1976). A commercially available test system designed for the 4-h identification of Enterobacteriaceae. Micro-ID, proved efficacious for the rapid biotyping of these two Haemophilus species. The nitrate reductase, indole production, ornithine decarboxylase, urease, and o-nitrophenyl-beta-D-galactopyranoside hydrolysis tests in Micro-ID correlated over 99% with conventional methodology. By utilizing the indole and o-nitrophenyl-beta-D-galactopyranoside tests it was possible, with 261 of 272 (96.1%) isolates, to distinguish H. influenzae from H. parainfluenzae. Cerebrospinal fluid isolates were over 90% H. influenzae biotype I, and conjunctival isolates were approximately 70% biotype II. Type b H. influenzae were predominantly biotypes I and II; these type b isolates were also overwhelmingly indole producers. Although over 90% of biotypes I and II have been reported to produce beta-lactamase, this was not confirmed by the small number of beta-lactamase producers encountered here. The 4-h Micro-ID should prove a useful mechanism, amenable to the routine clinical laboratory, for the further exploration of the association of Haemophilus with the site of isolation, antigenicity, and antibiotic resistance.

Bacteriological Techniques↗

PubMed1980

Photograms for microbiological assays.

The use of photograms provides a permanent record of microbiological assays in which diffusion of a substance in agar is measured. The accuracy of this procedure is comparable to direct measurement. This technique is inexpensive, does not require special photographic equipment, and is applicable to many tests commonly employed in clinical microbiology and immunology laboratories.

Agar↗