Clinical Case-Based Image Portfolios in Medical Histopathology.

This descriptive article describes the use of clinical case-based portfolios in histopathology teaching laboratories in conjunction with virtual microscopy not only to integrate histology and pathology disciplines for first and second year medical students but also to stimulate student engagement, promote self-directed and group-based learning and enhance student-to-student interaction in a structured manner. Portfolios consisted of PowerPoint files encompassing four to five clinical case studies relevant to the topics covered that week. Portfolios integrated study materials provided in the module-specific lectures, clinical skill lectures, and online interactive content. Two sets of portfolios, Individual and Group, were used. Individual Portfolios were completed by each student and uploaded prior to the laboratory session. Group Portfolios were completed by students working together in small groups during the laboratory session with minimal faculty assistance. The functional utility and acceptance of Individual and Group Portfolios among first- and second-year medical students was evaluated using electronic surveys and examination performances. Both first- and second-year students agreed that the use of portfolios in conjunction with virtual microscopy promoted understanding and encouraged discussion of the topics covered during the week and that group members worked well together and contributed to the completion of the portfolios. Performances on the Histology and Cell Biology and Pathology sections on the United States Medical Licensing Examination® (USMLE® ) remained consistent and in line with national averages. Overall, use of portfolios promoted peer teaching and contributed towards successful transition to the new system-based integrated curriculum with continued strong performance on the USMLE.

Fibrin ring granulomas in Rickettsia typhi infection.

We describe a 71-year-old man hospitalized for fever and productive cough. Laboratory investigation showed anemia, thrombocytopenia, elevated transaminases, hyponatremia, and hypoalbuminemia. Computerized tomography of the abdomen, thorax, and sinuses, echocardiography, and a gallium scan did not reveal the source of the fever. The patient remained febrile despite courses of piperacillin-tazobactam/azithromycin and ceftriaxone/vancomycin. A bone marrow biopsy showed fibrin ring granulomas, and 2 rickettsial serologic panels were positive for Rickettsia typhi infection and negative for Q fever. The patient was given doxycycline, and the fever resolved within 48 h. We propose that fibrin ring granulomas also occur in murine typhus.

Susceptibility of Neisseria meningitidis to 16 antimicrobial agents and characterization of resistance mechanisms affecting some agents.

Neisseria meningitidis represents a pathogen of great public health importance in both developed and developing countries. Resistance to some antimicrobial agents used either for therapy of invasive infections or for prophylaxis of case contacts has long been recognized, although specific guidelines for susceptibility testing have not been fully developed. We have examined the susceptibilities of a collection of 442 meningococcal clinical isolates from 15 countries to 16 antimicrobial agents. These included isolates recovered between 1917 and 2004, with representatives of all major serogroups. All isolates were tested by the Clinical and Laboratory Standards Institute (formerly NCCLS) broth microdilution method using Mueller-Hinton lysed horse blood broth, while a subset of 102 isolates was tested by agar dilution using Mueller-Hinton sheep blood agar. Most isolates provided adequate growth for MIC determinations by both broth and agar methods. Growth in broth was enhanced by CO(2) incubation and was required for two strains (1.7%). MICs of the study drugs compared favorably between the broth and agar methods (79 to 100% essential agreement), and MICs also generally agreed closely (92 to 100% essential agreement, excluding azithromycin) between broth tests incubated in the two different atmospheres. Elevated penicillin and ampicillin MICs (> or =0.12 microg/ml and > or =0.25 microg/ml, respectively) occurred in 14.3% and 8.6% of strains and were associated with polymorphisms of the penA gene encoding a modified penicillin-binding protein 2. None of the 442 isolates produced beta-lactamase. Elevated tetracycline and doxycycline (but not minocycline) MICs were associated with efflux-mediated resistance encoded by tet(B) in 13 strains. Resistance to sulfisoxazole in 21.7% of strains and to trimethoprim-sulfamethoxazole in 21.0% resulted from polymorphisms of folP encoding a modified dihydropteroate synthetase. Seven strains were resistant to rifampin due to mutations in the rpoB gene, and two strains were resistant to chloramphenicol due to production of chloramphenicol acetyltransferase mediated by catP. Two strains had reduced quinolone susceptibility due to mutations of gyrA. The determination of the susceptibilities of a large group of meningococcal strains (including strains with characterized resistance mechanisms) to 16 antimicrobial agents has served as the essential first step in defining susceptibility testing breakpoints specific for this organism.

Induction of telithromycin resistance by erythromycin in isolates of macrolide-resistant Staphylococcus spp.

Staphylococcal isolates were examined for possible macrolide-inducible resistance to telithromycin. All macrolide-resistant isolates demonstrated telithromycin D-shaped zones. This result did not discriminate between resistance due to an efflux mechanism (msrA) or a ribosomal target modification (ermA or ermC). Inducible telithromycin resistance in staphylococci does not appear to be analogous to inducible clindamycin resistance.

International clone of Neisseria meningitidis serogroup A with tetracycline resistance due to tet(B).

Thirteen Neisseria meningitidis clinical isolates from Africa, Asia, and the United States for which the tetracycline MICs were elevated (> or =8 microg/ml) were examined for 14 recognized resistance genes. Only the drug efflux mechanism encoded by tet(B) was detected. All isolates were in serogroup A, belonged to complex ST-5, and were closely related by pulsed-field gel electrophoresis analysis.

Development and verification of an automated sample processing protocol for quantitation of human immunodeficiency virus type 1 RNA in plasma.

We developed and verified an automated sample processing protocol for use with the AMPLICOR HIV-1 MONITOR test, version 1.5 (Roche Diagnostics, Indianapolis, Ind.). The automated method uses the MagNA Pure LC instrument and total nucleic acid reagents (Roche Applied Science, Indianapolis, Ind.) to extract human immunodeficiency virus type 1 (HIV-1) RNA from plasma specimens. We compared the HIV-1 load results for a dilution series (1 to 5 nominal log(10) copies/ml) and 175 clinical specimens processed by the automated method to those for the same samples processed by the manual methods specified by the manufacturer. The sensitivity, dynamic range, and precision of the viral load assay obtained by automated processing of specimens were similar to those obtained by an ultrasensitive manual processing method. The results were highly correlated (R(2), 0.95), and were in close agreement, with a mean difference of 0.09 log(10) (standard deviation, 0.292). The limits of agreement were +/-0.58 log(10) for results for samples processed by both the manual and the automated methods. These performance characteristics were achieved with a smaller sample volume (200 versus 500 microl) and without a high-speed centrifugation step and required only 15 min of labor for a batch of 32 samples. In conclusion, the automated sample preparation protocol can replace both the standard and the ultrasensitive manual methods used with the AMPLICOR HIV-1 MONITOR test and can substantially reduce the labor associated with this test.

Clinical evaluation of two methods for genotyping hepatitis C virus based on analysis of the 5' noncoding region.

We compared the performance characteristics of a standardized direct sequencing method (TRUGENE HCV 5'NC; Visible Genetics Inc., Toronto, Ontario, Canada) and a reverse hybridization line probe assay (INNO-LiPA HCV II; Bayer Corp., Tarrytown, N.Y.) for genotyping of hepatitis C virus (HCV). Both methods are based on detection of sequence heterogeneity in the 5' noncoding (5'NC) region. Concordance between the genotyping methods was assessed by testing 172 samples representing the six major genotypes. Sequence analysis of the more phylogenetically informative nonstructural 5B (NS5B) region was also done with 148 (86%) samples to confirm the accuracy of and resolve discrepancies between the 5'NC genotyping results. The sensitivities of the methods were assessed by using the 5'NC amplicon from both the qualitative and quantitative AMPLICOR HCV tests (Roche Diagnostics Corp., Indianapolis, Ind.). The ability of the methods to detect mixed-genotype infections was determined with mixtures of two different genotypes at relative concentrations ranging from 1 to 50%. Both 5'NC methods were able to genotype 99.4% of the samples with type agreement for 99.5% and subtype agreement for 68.2% of the samples. No or ambiguous subtype results were found by the line probe assay for 16.5% and by the TRUGENE 5'NC test for 17.1% of the samples. Discrepancies occurred between the line probe assay and NS5B results at the type level for 1.4% of the samples and at the subtype level for 14.2% of the samples. Discrepancies also occurred between the TRUGENE 5'NC and NS5B results at the type level for 2% of the samples and at the subtype level for 8.1% of the samples. We also found two distinct strains of HCV classified as type 2 by analysis of the 5'NC region that were type 1 by analysis of the NS5B region. The sensitivities of the two 5'NC genotyping methods were comparable and dependent on the amplification test used ( approximately 10(3) IU/ml with the qualitative HCV RNA tests and approximately 10(5) IU/ml with the quantitative HCV RNA tests). Genotype mixtures were successfully identified at a relative concentration of 5% by the line probe assay and 10% by the TRUGENE 5'NC test. In conclusion, the performance characteristics of the 5'NC methods were similar and both methods produced accurate results at the genotype level but neither method should be used for subtyping.