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Biomedical subjects

D Amsterdam

Publications and source records attributed to D Amsterdam.

72 records · Page 4Linked to original sources
PubMed1972

Plate-slide for the culture and morphological observation of fungi.

Adaptation of a polystyrene plate-slide is extremely well suited for the simultaneous macroscopic and microscopic diagnosis of fungi. This technique obviates the disorientation of identifying structures when cultures are mechanically disaggregated during preparation of slides for microscopy.

Fungi↗
PubMed1970

Plaquelike Clearings Induced by Antimicrobial Agents on Lawns of Pseudomonas aeruginosa.

Plaques similar in appearance to those induced by phage were observed adjacent to chloramphenicol and tetracycline discs on Pseudomonas aeruginosa lawns used for the determination of antibiotic susceptibility. Thirteen strains were selected for study, 10 of which exhibited the plaquing phenomenon. The ability to form plaques induced by tetracycline was not related to any of the biochemical properties of the strains studied, their overall antimicrobial susceptibility pattern, or their pathological source. Some pseudomonad strains were capable of pyocin production; however, the relationship between plaque formation and pyocin production was not apparent. Supernatant fluids of resuspended plaque contents of eight strains originally demonstrating clearings could induce plaques on sensitive indicator lawns only when collected from tetracycline-induced plaque areas; supernatant fluids of the same strains could not produce clearings without previous exposure to the drug. Of the eight supernatant fluids capable of plaque induction, three were active on their homologous indicator lawns. In a subsequent survey of 95 P. aeruginosa strains, it was found that 28 isolates exhibited plaques. Of these, 17 were associated with tetracycline, 7 were associated with chloramphenicol, 3 were associated with triple sulfa; and 1 was associated with nalidixic acid.

Journal Article↗
PubMed1969

Electronic data processing system for the clinical microbiology laboratory.

Owing to the increased volume of laboratory services and the shortage of skilled medical microbiologists who presently spend up to 30% of their time in clerical matters, pragmatic applications of electronic sorting techniques and computers should be considered to alleviate this problem. Moreover, surveillance of the hospital community, with particular reference to changing patterns of microbial resistance and the distribution of potentially infectious pathogens, requires detailed information which can be readily supplied by electronic sorting analysis. Mark-sense and prescored Port-A-Punch IBM cards were used to: (i) analyze antibiotic susceptibility data; (ii) tabulate total test loads according to conditions set down by the American Society for Clinical Pathologists; and (iii) to prepare a bacteriological report on the surveillance of hospital infections. After proper sorting and analysis, the cards also serve as a convenient reference file in the laboratory for pertinent information recorded by either blackening the appropriate areas (mark-sense style) or pushing out the preperforated rectangular holes with a simple inexpensive board and stylus (Port-A-Punch). No one scheme can fulfill the requirements of all laboratories or purposes, but ideas contained herein might serve as starting points for the design of similar systems in other laboratories.

Cross Infection↗
PubMed1968

Comparison of reagent-impregnated paper strips and conventional tests for distinguishing Escherichia from Aerobacter: correlation with colonial morphology.

The means for distinguishing Escherichia from Aerobacter (Enterobacter) differ in laboratories and range from complete dependence on colonial reactions on typical gram-negative media to reliance on one or more of the classical indole, methyl red, Voges-Proskauer, citrate (IMViC) parameters. Three colonial types (one prejudged as Escherichia) of lactose-positive rods were catalogued on each of the most commonly used selective media, MacConkey Agar, Endo Agar, and E M B Agar. Each cultural type was presumptively diagnosed and then compared with the expected outcome of individual IMViC tests. The distribution of preliminary identifications was similar from growth patterns on MacConkey Agar and E M B Agar, but it differed markedly from Endo Agar. When organisms initially diagnosed by cultural methods were compared by single IMViC tests, it was found that for each colonial type one of the biochemical parameters was best suited. Thus, for those types initially considered Escherichia, the methyl red or Voges-Proskauer test results agreed most consistently; for other types, the citrate reaction was most satisfactory. In addition, when newly formulated reagent-impregnated paper strip methods for indole, Voges-Proskauer, and citrate were evaluated and compared to the standard methods, agreement was 97% for indole, 90% for Voges-Proskauer, and 95% for Simmons' citrate.

Bacteriological Techniques↗
PubMed1968

New diagnostic system for the identification of lactose-fermenting gram-negative rods.

The identification of prompt lactose-fermenting gram-negative rods has generally relied heavily upon colonial morphology coupled with one or more indole, methyl red, Voges-Proskauer, citrate (IMViC) parameters, hydrogen sulfide, and motility. Studies were undertaken to compare diagnoses dependent solely upon the more orthodox criteria to a system for identification based upon hydrogen sulfide, ornithine decarboxylase, and citrate utilization (HOC). The results suggest that the IMViC scheme of identification is neither consistent nor applicable when applied to the current nomenclature of the above group of organisms and should be discarded, whereas the HOC system may prove to be of significant value to clinical microbiologists.

Bacteriological Techniques↗
PubMedDate not supplied

Comparative in vitro susceptibilities of 504 bacteremic isolates to ticarcillin plus clavulanic acid and other antimicrobial agents.

A total of 504 clinical bacteremic isolates were tested for susceptibility to ticarcillin-clavulanic acid and 12 other antibiotics. Ticarcillin-clavulanic acid showed superior antibacterial activity compared to penicillin, mezlocillin, piperacillin, ticarcillin, gentamicin, and amikacin against bacteremic isolates of methicillin-susceptible Staphylococcus aureus and Staphylococcus epidermidis. However, ticarcillin-clavulanic acid's activity was inferior to that of vancomycin against methicillin-resistant isolates of S. aureus and S. epidermidis. For Escherichia coli, Klebsiella oxytoca, Proteus mirabilis, Providencia stuartii, and lactose nonfermenting aerobic gram-negative bacilli, the activity of ticarcillin-clavulanic acid surpassed that of mezlocillin, piperacillin, and ticarcillin. Of the antimicrobial agents tested, ticarcillin, piperacillin, ceftazidime, and amikacin were the most active antibiotics against Pseudomonas aeruginosa.

Anti-Bacterial Agents↗
PubMedDate not supplied

Evaluation of the modified Visuwell Strep-A enzyme immunoassay for detection of group-A Streptococcus from throat swabs.

The modified Visuwell Strep-A enzyme immunoassay (EIA) was compared with culture for detection of group-A Streptococcus from throat swabs. Throat swabs in modified Stuarts medium obtained after culture at two institutions were tested in Visuwell. Cumulative results were n = 417, sensitivity 87.8%, specificity 89.9% predictive value positive (PVP) 67.9%, predictive value negative (PVN) 96.8%, and accuracy 89.5%. At another site, swabs were delivered to the laboratory without transport medium, cultured, and subsequently tested by Visuwell (n = 202, sensitivity 79.6%, specificity 84.5%, PVP 65.2%, PVN 91.9%, accuracy 83.2%). When 1+ culture-positive specimens were considered negative, the sensitivity and PVN increased from 79.6% to 90.2% and 91.9% to 97.1% respectively. Overall performance of the modified Visuwell was comparable with that of the initial assay for throat swabs transported with or without modified Stuarts medium. Cross reaction with organisms other than group-A Streptococcus normally found in the oropharynx was negligible in Visuwell and the limit of detection of group-A Streptococcus was 5 x 10(4) colony-forming units.

Cross Reactions↗
PubMedDate not supplied

Polymerase chain reaction assays for the detection of cytomegalovirus in organ and bone marrow transplant recipients.

Cytomegalovirus (CMV) infection is ubiquitous and results in a wide spectrum of clinical manifestations ranging from asymptomatic infection to severe life threatening disease. Infection in normal children and adults usually causes no symptoms but in the immunocompromised host, CMV may result in severe opportunistic infections with high morbidity and mortality. Historically, virus detection was dependent on culture of the virus or on a centrifugation culture system referred to as a shell vial assay. The shell vial assay frequently lacked sensitivity and was unable to detect infection in its early phase. Also, as with culture assays, the results were affected by antiviral therapy. The CMV antigenemia assay was developed to provide more rapid results and has gained wide usage. This assay is limited to detection of the virus in white blood cells and is more sensitive than culture or the shell vial assay. Application of the polymerase chain reaction (PCR) to these problems has resulted in the development of assays for CMV which are more sensitive than previously available methods. This method employs liquid hybridization with 32P labeled probes and gel retardation analysis for detection of amplified DNA specific for each virus. A comparison of the detection of CMV by an antigenemia assay or the PCR method in the leukocytes of renal transplant patients revealed that the PCR assay detects cytomegalovirus earlier and more consistently than the antigenemia assay. Finally, the application of a fluorescent dye detection system and image analysis of the acrylamide gel with a laser scanner provides additional sensitivity to the detection of cytomegalovirus, as well as avoiding the use of radioactivity, making the assay more adaptable to the clinical laboratory.

Bone Marrow Transplantation↗
PubMedDate not supplied

The laboratory diagnosis of tuberculosis in a period of resurgence: challenge for the laboratory.

OBJECTIVE: To review the current and contemporary approaches to the laboratory diagnosis of Mycobacterium tuberculosis and related mycobacteria. DATA SOURCES: Current literature. STUDY SELECTION: Determined by the author. DATA EXTRACTION: Determined by the author. DATA SYNTHESIS: The definitive diagnosis of mycobacterial disease depends upon the laboratory for the isolation and identification of the infecting microorganism. Laboratory studies encompass microscopic examination for the presence of AFB; isolation and recovery of the organism by cultural methods; phenotypic biochemical or other contemporary means to identify the recovered organism; and anti-tuberculosis susceptibility testing. Because of the extended growth period of this group of organisms, it is imperative that the lab use the most rapid means to provide information to the clinician for isolation of the patient if needed and for the initiation of prompt rational therapy as determined by susceptibility testing. More than 25 species in the Mycobacterium genus are capable of causing human disease. In the United States, the five most frequently encountered species are M. tuberculosis, M. avium, M. kansasii, M. fortuitum and M. chelonei. CONCLUSION: Tuberculosis is a reemerging disease with significant health problem implications in the US and worldwide. Diagnosis and appropriate treatment are dependent on the prompt response of the laboratory.

Bacteriological Techniques↗
PubMedDate not supplied

Evaluation of HLA-DR typing by ethidium bromide fluorescence.

Sixty individuals were typed for D-related human leukocyte antigens (HLA-DR) using two methods: the standard eosin exclusion method and a recently described one-color ethidium bromide technique. As a result, 88 of the 90 DR antigens detected by the standard technique were also detected by one-color fluorescence (sensitivity = 97.8 percent). However, of the 99 DR antigens identified by ethidium bromide fluorescence, 11 were left undetected by eosin exclusion (sensitivity = 88.9 percent). The one-color ethidium bromide fluorescence technique, although originally intended to conserve technical time, demonstrated an additional advantage in our laboratory. The enhanced sensitivity of the procedure may help in the identification of previously undetected DR antigens.

Ethidium↗