[Septic shock with purpura fulminans after a dog bite]. / Sepsis mit Purpura Fulminans nach Hundebiss.

HISTORY AND CLINICAL FINDINGS: A 61-year-old man presented with a four-day history of back pain and nonspecific abdominal pain. His condition had significantly worsened since the day before admission with generalized weakness and dyspnea. His temperature was 39.1 C, he had tachycardia and was tachypneic. Peripheral cyanosis was noted. The abdomen was soft with mild epigastric tenderness. A diffuse skin rash developed with increasing petechial bleeding and central necrosis. It was revealed that he had been bitten by a dog several weeks before admission. INVESTIGATIONS: Laboratory data indicated an acute inflammatory process with a marked increase in white blood cells and C-reactive protein. An elevated procalcitonin level suggested a systemic bacterial infection. Chest X-ray and abdominal CT scan were unremarkable. Echocardiography revealed a globally hypokinetic heart with no evidence of valvular vegetations. One set of blood cultures grew micro-aerophilic, Gram-negative rods. Gene sequencing identified the slow growing, fastidious bacillus as CAPNOCYTOPHAGA CANIMORSUS. TREATMENT AND COURSE: The patient was admitted to the intensive care unit and initially treated with intravenous piperacillin/tazobactam and hydrocortisone for septic shock. Transfusions of platelets and blood products were given because of disseminated intravascular coagulation. The patient developed multi-organ failure requiring ventilation and hemodialysis; he died four days after admission. CONCLUSIONS: As a rare cause of septicemia, especially in immunocompromised patients, Capnocytophaga canimorsus infection should be considered after an animal bite. Given the slow growth of this bacterium in culture, Gram-staining of a peripheral blood smear may provide an early diagnosis and avoid delay before appropriate antibiotic therapy, which may favorably influence the potentially fatal course, is started.

Medical students and radiology residents: can they learn as effectively with the same educational materials?

RATIONALE AND OBJECTIVES: The purpose of this study was to evaluate the effectiveness of resident-prepared, independent-learning materials for teaching chest radiology to medical students. MATERIALS AND METHODS: Students from three U.S. medical schools enrolled in radiology clerkships between March 1998 and June 1998 were randomly divided into control (n = 27) and experimental (n = 31) groups. The experimental group studied 12 chest radiology independent-learning cases (intervention) used to teach radiology residents in a previous study. Both groups took a 36-item, multiple-choice test (previously used to test radiology residents) on three occasions (before intervention [pretest], 1 day after intervention [posttest], and 2-4 weeks after intervention [final examination]). Student scores were then compared with resident scores. RESULTS: Mean scores were similar across institutions at pretest, but increases at posttest and final examination scores differed across time, school, and group (P < .005). Mean differences in scores between experimental and control groups at pretest, posttest, and 2-4-week final examination were -0.22, 9.79, and 9.14, respectively, demonstrating increased performance at posttesting that remained present (though slightly attenuated) 2-4 weeks later. Comparing performance, residents had mean pretest scores of 19.2 and students of 14.1, a five-point difference attributable to the residents' greater experience. Both residents and students gained approximately nine points at posttest. At final examination, the difference between residents and students was only 1.4 points, suggesting the experimental program (teaching materials) brought students close to the long-term retention shown by residents. CONCLUSION: Independent study of resident-prepared chest radiology teaching cases increased medical student knowledge for at least 2 or 4 weeks after instruction. Although starting at lower knowledge levels, students experienced gains in knowledge comparable to those of residents, suggesting the same materials can be used to teach both students and residents.

Effects of 17alpha,20beta-dihydroxy-4-pregnen-3-one on cortisol production by rainbow trout interrenal tissue in vitro.

Physiological levels of 17alpha,20beta-dihydroxy-4-pregnen-3-one (17, 20-P) stimulated time- and dose-dependent increases in cortisol production by rainbow trout (Oncorhynchus mykiss) interrenal tissue cultured in vitro. Significant stimulation occurred in response to 100, 300, and 1000 ng/ml of 17,20-P. Lower doses were ineffective. Elevated cortisol levels were observed 1 hr after addition of 300 ng/ml 17,20-P. No additive or synergistic interaction was evident between human adrenocorticotropin fragment 1-24 (ACTH1-24) and 17, 20-P in stimulating cortisol secretion, although 300 ng/ml 17,20-P could further enhance cortisol production above levels already stimulated by 300 ng/ml ACTH. 17alpha, 20alpha-dihydroxy-4-pregnen-3-one also stimulated cortisol secretion, but was only half as effective as 17,20-P. Estradiol-17beta, testosterone, and 11-ketotestosterone had no effect on cortisol secretion. Inhibitors of mRNA and protein synthesis had no effect on 17,20-P-stimulated cortisol production. Radiotracer studies demonstrated that the bioconversion of 17,20-P to cortisol could fully account for the cortisol produced by the interrenal in response to 17,20-P and demonstrated that rainbow trout interrenal cells contain an active 20beta-hydroxysteroid dehydrogenase. These data suggest that 17,20-P may be a regulator of cortisol production during the periovulatory period in salmonid fishes.

Isolation of catalase-negative Listeria monocytogenes strains from listeriosis patients and their rapid identification by anti-p60 antibodies and/or PCR.

Two catalase-negative Listeria monocytogenes serovar 1/2b strains were isolated from listeriosis patients in 1995 in Germany. The infections appeared in individuals from different cities at different seasons and were caused by L. monocytogenes strains of different clonal types. In particular, the catalase reaction of one strain isolated from blood was consistently negative, whereas this reaction was only reversibly blocked when the strain was freshly isolated from ascitic fluid. After subculturing, the catalase-positive reaction was restored. Initially, identification of these isolates was difficult to achieve not only because of the lack of a catalase reaction, which generally distinguishes L. monocytogenes from other morphologically similar pathogenic gram-positive bacteria, but also because other routinely used biochemical tests such as CAMP and the commercial API test gave unclear results. However, rapid and unequivocal identification of these strains was possible by analyzing secretions of the p60 protein in culture supernatants by enzyme-linked immunosorbent assay or Western blot (immunoblot) analysis with our recently developed Listeria- and L. monocytogenes-specific anti-p60 antibodies. Additionally, the identifications were confirmed by Listeria- and L. monocytogenes-specific PCR analyses with primers derived from the iap, hly, and prfA genes. Immunoanalyses also allowed for the differentiation of these two strains, whereas no differentiation was possible by PCR when the internal, variable repetitive iap gene portion was analyzed. However, size variations of the PCR products comprising these gene portions which were obtained from a number of L. monocytogenes strains belonging to the same serotypes indicated that this type of PCR is not only useful for specific identifications but may be used in parallel as an additional marker for epidemiological studies. In conclusion, the data suggest that catalase production should not be taken as a strict criterion for the identification of listeriae. Furthermore, at least the infection caused by the stably catalase-negative strain supports the notion that catalase does not seem to be necessary for the intracellular growth of L. monocytogenes.

Adherence to bovine neutrophils and suppression of neutrophil chemiluminescence by Mycoplasma bovis.

The adherence of viable and heat-treated Mycoplasma bovis to bovine peripheral blood neutrophils was studied by specific immunofluorescence staining and flow cytometry. Viable and heat-treated M. bovis cells, adhered to bovine neutrophils in dose-dependent fashion within a 30 min incubation. Fluorescence quenching using crystal violet indicated that unopsonized M. bovis cells remained on the surface of bovine neutrophils without experiencing significant ingestion. The effect of M. bovis adherence on neutrophil microbicidal function was examined by measuring luminol enhanced chemiluminescence (CL). Adherent M. bovis cells did not elicit a bovine neutrophil CL response over a 75 min incubation period. M. bovis inhibited the capacity of bovine neutrophils to mount a CL response. Inhibition occurred whether viable or heat-treated M. bovis cells were used and it occurred when neutrophils were stimulated with opsonized zymosan (OZ) or phorbol myristate acetate (PMA). Inhibition of the PMA stimulated neutrophil CL response required cytadherence by M. bovis cells. These findings suggest that activation of the bovine neutrophil respiratory burst was inhibited at or distal in the pathway to the activation of protein kinase C (PKC), the site of PMA stimulation, and that it was mediated by a direct interaction between the adhering M. bovis cells and the bovine neutrophil membrane.