Students in compensatory education programs: analysis of scores on performance assessments for the Iowa Test of Basic Skills.

Analysis of Mathematics and Language Arts scores for 11,438 fourth- and 8,972 seventh-grade students in compensatory education programs on the performance assessments for the Iowa Test of Basic Skills indicated the students performed poorly, particularly in mathematics.

Rapid and effective method for preparation of fecal specimens for PCR assays.

We have developed a novel method for the preparation of fecal specimens for PCR assays. Approximately 100 mg of solid stool or 200 microliters of liquid fecal sample was thoroughly suspended in 1 ml of water. Fecal debris was removed by low-speed centrifugation (2,800 x g for 2 min). The supernatant was then boiled for 10 min in a water bath and further clarified by high-speed centrifugation (12,000 x g for 5 min). Fifty microliters of the clarified supernatant was then purified by Sepharose CL-6B spin column chromatography, and a portion of the purified supernatant was used for PCR. By this method, stools containing enterotoxigenic Escherichia coli H10407 were amplified by colonization factor antigen I fimbrial gene PCR, with a sensitivity of 100 organisms per reaction. The method was also effective for processing stool specimens for Clostridium difficile toxin A and B gene PCRs. This method is rapid, effective, and simple to perform and will improve the applications of PCR to stool specimens for diagnostic purposes.

Multicenter evaluation of four methods for Clostridium difficile detection: ImmunoCard C. difficile, cytotoxin assay, culture, and latex agglutination.

A three-center study was undertaken to compare several test methods for the detection of Clostridium difficile, associated toxin, or related markers by using 927 stool specimens. Methods included direct assay of cytotoxin in stool by tissue culture, C. difficile bacterial culture followed by cytotoxin assay, bacterial culture alone, latex agglutination assay, and the ImmunoCard C. difficile test (Meridian Diagnostics, Inc.). The sensitivities, as determined against direct cytotoxin assay results, of the ImmunoCard C. difficile and latex agglutination assays were 84 and 67%, respectively (92 and 77%, respectively, when adjusted for bacterial culture outcomes). Evaluation for C. difficile-associated disease (CDAD) among 864 patients was based on clinical criteria for antibiotic-associated diarrhea combined with laboratory evidence of toxin or toxin-producing C. difficile in stool specimens. The sensitivity of each test method for screening of CDAD was as follows: bacterial culture, 95%; culture with cytotoxin assay of isolates, 90%; ImmunoCard C. difficile test, 83%; cytotoxin assay 82%; and latex agglutination assay, 67% (P < or = 0.05 versus all other methods). The standard deviations of the test sensitivity statistics between study sites were ranked as follows: cytotoxin assay (+/- 3.1%) < ImmunoCard C. difficile test (+/- 5.7%) < latex agglutination assay (+/- 12.3%) < culture (+/- 24.7%) < culture with cytotoxin assay (+/- 28.0%). The data support the use of the ImmunoCard C. difficile test as an adjunct for the diagnosis of CDAD.

Current issues and problems in dealing with anaerobes in the clinical laboratory.

Because of the current concern for health care reform and the demands placed in the clinical microbiology laboratory by decreased resources, questions regarding appropriate work-up of anaerobes remains unresolved. Although anaerobes are ubiquitous, the number of anaerobes causing disease is relatively few. This article focuses on the need for isolation and identification of these anaerobes and emphasizes proper collection, culture, and identification techniques. Varying levels of expertise in isolation and identification of anaerobes are proposed, and the role of "rapid" identification kits in identification of these organisms is discussed.

Cellular fatty acid analysis in the differentiation of Clostridium in the clinical microbiology laboratory.

The identification of Clostridium species can be problematic for the diagnostic microbiology laboratory. The introduction of the MIDI Microbial Identification System (MIS) has enabled personnel in diagnostic laboratories to perform cellular fatty acid analyses on a variety of microorganisms. We used the Virginia Polytechnic Institute (Blacksburg, VA) Anaerobe Library (Moore Version 3.8) to perform analyses on 216 strains representing 18 species of Clostridium. The organisms were characterized with use of traditional biochemical methods that employ prereduced anaerobically sterilized media and other reference diagnostic methods. The MIS identified 86% of the strains correctly to the species level without the need for supplemental tests, and identified an additional 6% of the strains to species levels with the aid of a few supplemental tests. Only 3% of strains were identified by genus incorrectly. The cellular fatty acid patterns of selected, medically important clostridia were so distinctive that 100% of these species were identified correctly. The MIS has many practical benefits, including speed of identification, and few disadvantages (such as equipment cost) for the clinical microbiology laboratory.

Comparison of five cultural procedures for isolation of Clostridium difficile from stools.

Several procedures have been described for the culture of Clostridium difficile from stool specimens. The goal of this study was to determine the effectiveness of five of these methods for the isolation of C. difficile from feces of patients suspected of having C. difficile-associated illness. A total of 564 stool specimens were cultured by using heat shock, ethanol treatment (ET), and direct plating on Carr-Scarborough cycloserine-cefoxitin-fructose agar (CCFA) with horse blood (C/S medium), BBL CCFA medium, and Remel C. difficile agar. Cytotoxin assays were performed on all specimens. A total of 113 specimens (20%) were positive for C. difficile by one or more methods. The numbers of positive cultures by using heat shock, ET, and direct plating on C/S medium, BBL CCFA medium, and Remel C. difficile agar were 79 (70%), 89 (79%), 91 (81%), 79 (70%), and 52 (46%), respectively. We concluded that ET and direct plating on C/S medium were the most effective procedures for isolating C. difficile from stool specimens and found significant variation in the performance of modified CCFA from different manufacturers.

Evaluation of the new RapID-ANA II system for the identification of clinical anaerobic isolates.

The RapID-ANA II System (Innovative Diagnostic Systems, Inc., Atlanta, Ga.) is a recently revised and marketed 4-h system for the identification of anaerobic bacteria. The system was compared with conventional identification methods for its ability to identify 566 clinical anaerobic isolates. Overall, the system identified correctly to genus and species 68% of the total isolates (62% of 204 gram-negative bacilli, 70% of 69 nonsporeforming gram-positive bacilli, 74% of 130 Clostridium isolates, and 72% of 163 anaerobic cocci), without the use of additional tests. With the additional tests suggested by the manufacturer, 78% of the total isolates were identified correctly to species. The routine use of a few simple and practical tests (e.g., egg yolk agar for Clostridium spp.), in addition to the RapID-ANA II, would improve significantly the accuracy of the system in the identification of anaerobic bacteria. This second-generation system offers a number of improvements over the original system, including an updated data base and the option of overnight refrigeration of the system before the addition of reagents.

Characterization of anaerobic bacteria by using a commercially available rapid tube test for glutamic acid decarboxylase.

A rapid glutamic acid decarboxylase microdilution test for presumptive identification of certain anaerobic bacteria was marketed recently by Carr-Scarborough Microbiologicals, Inc., Stone Mountain, Ga. The test was evaluated with 474 clinical isolates, representing 11 genera and 54 species, and was found to be a useful aid in the presumptive identification of Bacteroides fragilis, B. distasonis, B. vulgatus, B. thetaiotaomicron, B. ovatus, B. uniformis, B. eggerthii, Clostridium perfringens, C. barati, C. sordellii, and Eubacterium limosum.

Evaluation of a commercial latex test for Clostridium difficile for reactivity with C. difficile and cross-reactions with other bacteria.

Seventy-eight species of bacteria (739 isolates) were tested for reactivity with a commercial latex test for Clostridium difficile. All noncytotoxic as well as cytotoxic strains of C. difficile reacted positively. Immuno-specific cross-reactions were found only with C. sporogenes, proteolytic C. botulinum, and Peptostreptococcus anaerobius.

DNase production by Clostridium septicum.

Sixty-two Clostridium septicum isolates were assayed for extracellular DNase activity. All of the C. septicum isolates tested produced greater DNase activity than did the other DNase-producing clostridial isolates tested. The molecular weight of the DNase of C. septicum was determined to be approximately 45,000. DNase is a major extracellular protein produced by this organism.

Diabetic foot infections. Bacteriologic analysis.

Diabetic patients with foot infections were prospectively evaluated over a two-year period. Cultures from reliable specimens avoiding contamination with foot ulcers were obtained in 54 infectious episodes. Staphylococcus species, Enterococcus species, Corynebacterium species, and various species of Enterobacteriaceae were commonly isolated. Common anaerobic isolates included Peptostreptococcus magnus, Peptostreptococcus prevotii, and Bacteroides species. Results of cultures from 94 unreliable specimens were similar. Results of reliable and unreliable specimens obtained simultaneously in 26 patients agreed in seven (27%), but antibiotics selected for organisms isolated from unreliable specimens would have adequately covered pathogens found in the reliable culture in 24 (93%). Diabetic foot infections usually involve mixed bacterial flora, including aerobic, facultatively anaerobic, and anaerobic microorganisms. Specimens should be obtained from infected tissue that does not communicate directly with the foot ulcer if possible. If such specimens are not available, cultures of purulent exudate within the foot ulcer or soft-tissue sinuses may provide useful information on which to base decisions about antibiotic therapy. Broad-spectrum beta-lactam antibiotics or a combination of antibiotics active against facultatively anaerobic cocci and bacilli as well as anaerobes provide the best empirical antimicrobial coverage in these patients.

Discrimination of computer-synthesized speech.

The effects of learning on the discrimination of computer-synthesized speech was assessed by presenting 100 computer-produced monosyllabic words to 2 groups of 15 adult subjects. One group's errors were corrected while the other group's errors were uncorrected. A comparison of errors on the first 50 vs the second 50 presentations showed significant improvement for corrected group only. It was concluded that the discrimination of computer-synthesized monosyllables can be improved with correction of errors but is still about 14% poorer than the discrimination of human speech.