Listeria Monocytogenes Infections in Metropolitan Toronto: A Clinicopathological Study

The clinical and laboratory findings in 21 patients with listeriosis are described and the subject is reviewed. Eleven of the infections were septicemias of newborns, eight were meningitis in infants or adults, and two other children had unusual manifestations.Neonatal septicemia was rapidly fatal; one of 11 infants survived. The disease often seemed traceable to mild maternal infection during the third trimester usually leading to premature delivery of critically ill babies. Only awareness of the possible presence of listeriosis and early antibiotic therapy seem capable of reducing this high mortality.Tissues from autopsies showed characteristic microscopic necrotic foci with mononuclear infiltration progressing to microabscesses containing small Gram-positive rods. Lesions were found in the one placenta examined.Five infants with meningitis recovered, and one of three affected adults. Specific diagnosis depends on demonstrating Listeria monocytogenes; differentiation from other forms of acute meningitis cannot be made clinically.One older child had septicemia and another had listerial pharyngitis. Both recovered.     

Orcein staining and the study of the effect of chemicals on chromosomes

Summary Plant materials of both dicotyledonous and monocotyledonous groups were subjected to treatment with alloxan followed by coumarin, phenols, oxyquinoline etc. for 3 to 4 hours.Root tips were then heated in an orcein-acid mixture for 10 to 40 seconds and studied after mounting in 1% orcein. Clear metaphase plates were obtained after 10 seconds of heating, whereas after 20 and 30 seconds considerable erosion and fragmentation respectively were recorded. Complete loss of stainability resulted after heating for 40 seconds.Fragmentation is caused only by orcein under heat conditions. This is demonstrated by control series checking all variables.Pretreatment with the chemicals stated is of absolute necessity for fragmentation. It is suggested that this pretreatment causes depolymerisation of DNA and lability of nucleoprotein linkage at certain segments from which the DNA becomes detached during subsequent heating.Of all the chemicals tested for pretreatment effects, marked positive results were obtained with alloxan (1 hour) followed by coumarin (2 hours at 16–20 ° C.). Phenols also gave positive results. The other chemicals tried need slightly longer time of treatment for fragment induction.