Microbiologica最新文献

Xylan induced the production of xylanase by Verticillium dahliae. Other cellulolytic enzymes such as glucanase and beta-glucosidase were synthesized in smaller quantities. The process of degradation indicated that xylanase behaved like a typical endo-enzyme causing first production of high mol, wt. products, and indicated that V. dahliae produced at least three enzymes which degrade xylan.

Fourteen strains of Clostridium difficile, previously characterized by SDS-PAGE, were examined for the presence of surface structures. None of the strains were fimbriated but, when grown in the presence of glucose, all exhibited a thin ruthenium red-positive layer. Two strains, belonging to different electrophoretic groups, were also observed after treatment with homologous and heterologous antisera. The strain belonging to the electrophoretic group 2, usually associated with the disease, showed a 30-80nm thick capsule in ultrathin sections. The strains belonging to group 5, mainly observed in isolates from healthy children, exhibited a thinner polysaccharide layer (10-20 nm). No stabilization was observed when these strains were treated with heterologous antisera. This capsule-like material did not seem to be associated with adhesive properties of C. difficile strains.

A series of 52 serum samples from chronic HBsAg carriers was tested for the presence of HBV-DNA by means of the Polymerase Chain Reaction (PCR) and Liquid Phase Hybridization (LPH). The samples were obtained from two groups of patients: group A included 34 chronic HBsAg carriers ("healthy" individuals) without hepatocytolysis or viral replication; group B included 18 chronic HBsAg carriers with signs of hepatocytolysis (ALT levels at least twice the normal value) and activated markers of viral replication. PCR was superior to LPH in group A, with 7/34 versus 5/34 positive samples being detected, respectively. No difference in sensitivity was found between the two techniques in group B, since 9/18 samples were positive both cases. The data stress the need to adopt PCR for the HBV-DNA screening of HBeAg-/HBsAg+-carriers.

A comparative study on the endotoxic effects of lipopolysaccharide (LPS) from Veillonella parvula ATCC 10790 and from Bacteroides intermedius BMH was performed using an in vivo approach in the C57BL/6 mouse. Phenol-water extracted LPS of such anaerobes was purified by ultracentrifugation and DNase/RNase digestion, and characterized by a metachromatic assay for endotoxins and by electrophoresis on SDS-polyacrylamide gel and silver staining. Mouse LD50 for V. parvula LPS was 1.479 mg and for B. intermedius greater than 3.160 mg. Sublethal amounts of the LPS from anaerobes as well as from facultative aerobes decreased daily water intake and body weight in the mouse. Endotoxin from Salmonella typhimurium SL1102, Escherichia coli 0128:B12 and V. parvula had a strong effect on water intake and body weight, whereas Bacteroides intermedius LPS activity was very weak. The results of the present report suggest that V. parvula LPS has a toxic in vivo activity on mouse, which is comparable to LPS from classic enteric organisms and stronger than B. intermedius LPS.

Lyme Borreliosis is an infectious disease caused by the Borrelia burgdorferi spirochete transmitted to man by a tick bite. The aim of this study was to assess the predictive value of tick bites for the diagnosis of Borreliosis in a sample of 266 subjects residing in an endemic area of north-eastern Italy. In the serological diagnosis of Borreliosis, positive and negative predictive values of tick bites were found to be 24% and 88% respectively.

Three strains of Shigella dysenteriae type 2 were isolated from a small household outbreak which occurred in Palermo, Sicily, during summer 1990. Two isolates were recovered from hospitalized patients and one from an asymptomatic carrier. The infection could not be associated with travel to foreign countries or contact with travellers returned from abroad. Since 1953 S. dysenteriae has been never isolated in Southern Italy. The isolates from dysentery cases were susceptible to antibiotics and carried a plasmid of 120 MDa associated with a small cryptic plasmid; in contrast, the strain isolated from the healthy carrier contained an additional plasmid of approximately 40 MDa, which codified for resistance to ampicillin, streptomycin, sulfamethoxazole and trimethoprim. All strains showed some atypical biochemical properties, but their rRNA-DNA patterns of hybridization were closely similar to that of the reference strains of type 2 and easily distinguishable from those of the other types of non-Shiga bacillus reference strains. Epidemiological isolation features of these strains suggest a possible circulation of this Shigella species in Sicily. Genetic characterization of these strains may be useful for surveillance of infections by this organism.

Between 1987 and 1989, the prevalence of antibodies to Toxoplasma gondii was determined by ELISA in serum samples from 1,494 apparently healthy subjects, 3-18 years old. Subjects were selected by a systematic cluster sampling from five geographical areas in Italy. The overall prevalence of antibodies was 17.9%, increasing from 4.7% in 4-6 year olds to 28.4% in 17-18 year olds (P less than 0.01). A slight predominance was observed among males (18.2% vs. 17.5% in females), as well as among subjects residing in Southern Italy and the Islands (21.9% vs. 19.2% in subjects residing in the North), but neither difference was statistically significant. Toxoplasma infection was associated with sociodemographic factors. Subjects belonging to a household with six or more persons had a 1.8-fold risk (C.I. 95% = 1.3-2.6) and subjects whose fathers had less than six years of schooling had a 2.7-fold rosk (C.I. 95% = 1.8-3.9) of previous exposure to toxoplasma infection. Considering the large proportion (70%) of young women entering childbearing age without toxoplasma antibodies, it appears that the risk of congenital toxoplasmosis will not be negligible in Italy in forthcoming years.

In January 1989, the prevalence of antibodies to hepatitis A virus (anti-HAV) was determined by ELISA in 702 apparently healthy children 5-14 years old in Kumba City, Cameroon. Children were recruited from those attending six different primary schools, representative of the socio-demographic characteristics of the inhabitants, using a systematic random sampling. The overall IgG anti-HAV prevalence was 96.9%, reaching 100% by the age of 11 years. In primary school beginners the prevalence was very high, 94.0%, contrary to what has been observed in developed countries. The anti-HAV prevalence was not associated with family size, but was related to parent's occupation, children from the lower class having a 5.9 fold risk (C.I. = 1.9-18.3) of past exposure to HAV. These results suggest a persistently high prevalence of anti-HAV in children despite improving hygienic conditions. The spread of HAV in this population may be the result of domestic water and/or food contamination.

The present work investigated antigenic variations of the most immunogenic polypeptides of Cytomegalovirus (CMV), namely two nonstructural polypeptides of MW 72 Kd and 52 Kd, and 5 structural proteins of MW 150, 65, 58, 38 and 28 Kd, in several low-passage CMV isolates from urine of infected children. The polypeptides showing the greatest variations were the non structural p72 and p52, and the structural proteins p65 and p38. Furthermore the reactivity of the children's sera was studied with regard to the antigenic proteins of the homologous virus strain. We failed to recognize any reactivity pattern typical of an acute CMV infection and the results obtained indicate that CMV-infected children may have a very low and variable IgG and IgM response, p150 and p65 being the two most often recognized antigens.

Pigs which had been vaccinated with the Lapinized Chinese strain of Hog Cholera Virus previously adapted in a minipig cell line cultures (MPK-LC-HCV), resultet to be protected when they were subjected to challenge infection with virulent Hog Cholera Virus (HCV) 6 or 11 months later. The challenge virus was never isolated from any of the vaccinated pigs. The MPK-LC-HCV vaccine induced a significant rise of the antibody titer to the HCV in pigs kept under field conditions.