Stability of related human and chicken Campylobacter jejuni genotypes after passage through chick intestine studied by pulsed-field gel electrophoresis.
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The genomic stability of 12 Campylobacter jejuni strains consisting of two groups of human and chicken isolates was studied by analysis of their PFGE (pulsed-field gel electrophoresis) patterns after passage through newly hatched chicks' intestines. The patterns of SmaI, SalI, and SacII digests remained stable after intestinal passage, except for those of two strains. One originally human strain, FB 6371, changed its genotype from II/A (SmaI/SacII) to I/B. Another strain, BTI, originally isolated from a chicken, changed its genotype from I/B to a new genotype. The genomic instability of the strains was further confirmed by SalI digestion and ribotyping of the HaeIII digests. In addition, heat-stable serotype 57 of strain FB 6371 changed to serotype 27 in all isolates with new genotypes but remained unchanged in an isolate with the original genotype. Serotype 27 of strain BTI remained stable. Our study suggests that during intestinal colonization, genomic rearrangement, as demonstrated by changed PFGE and ribopatterns, may occur. (+info)
Humoral immune responses to Neisseria meningitidis in children.
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An understanding of the nature of immunity to serogroup B meningococci in childhood is necessary in order to establish the reasons for poor responses to candidate vaccines in infancy. We sought to examine the nature of humoral immune responses following infection in relation to age. Serum bactericidal activity was poor in children under 12 months of age despite recent infection with Neisseria meningitidis. The highest levels of bactericidal activity were seen in children over 10 years of age. However, infants produced levels of total immunoglobulin G (IgG) and IgG subclass antibodies similar to those in older children in a meningococcal enzyme-linked immunosorbent assay. Most antibody was of the IgG1 and IgG3 subclasses. This striking age dependency of bactericidal antibody response following infection is not apparently due to failure of class switching in infants but might be due to qualitative differences in antibody specificity or affinity. (+info)
Comparative physical and genetic maps of the virulence plasmids of Salmonella enterica serovars typhimurium, enteritidis, choleraesuis, and dublin.
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Using fragment profiling, PCR, and Southern hybridization, we found that Salmonella enterica serovar Choleraesuis harbored virulence plasmids of various sizes, whereas serovars Typhimurium, Enteritidis, and Dublin carried a plasmid of a unique size. Also, the virulence plasmid of Typhimurium contained genes in the same order detected in the other three plasmids, all of which contained deletions. (+info)
Streptococcus intestinalis Robinson et al. 1988 and Streptococcus alactolyticus Farrow et al. 1984 are phenotypically indistinguishable.
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The one-dimensional whole-cell protein patterns and a variety of biochemical characteristics of the type and reference strains of Streptococcus intestinalis and Streptococcus alactolyticus were studied. All the data revealed that strains of both species were indistinguishable. Reported differences in haemolytic activity and presence of Lancefield antigens were not reproduced. All strains were alpha-haemolytic. The S. intestinalis type strain possessed the group G antigen, but a second S. intestinalis reference strain and all of the S. alactolyticus strains possessed the group D antigen. All strains produced urease activity (albeit some after prolonged incubation), a characteristic considered important for S. intestinalis. Given the congruence between whole-cell protein electrophoresis and percentage of DNA-DNA hybridization, these data suggest that Streptococcus intestinalis Robinson et al. 1988 is a junior synonym of Streptococcus alactolyticus Farrow et al. 1984. (+info)
Further determination of DNA relatedness between serogroups and serovars in the family Leptospiraceae with a proposal for Leptospira alexanderi sp. nov. and four new Leptospira genomospecies.
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DNA relatedness was determined among 303 strains of Leptospira and Leptonema. Included in the analysis were reference strains from 228 well-characterized and recognized serovars. The study included 268 serovars from 29 named and one or more unnamed serogroups. The strains clustered into 17 DNA hybridization groups, representing 12 previously described species (292 strains) and five new genomospecies (11 strains). The largest groups included Leptospira interrogans (91 strains from 82 serovars), Leptospira santarosai (65 strains from 59 serovars), Leptospira borgpetersenii (49 strains from 43 serovars), Leptospira kirschneri (29 strains from 26 serovars) and Leptospira noguchii (20 strains from 20 serovars). The new genomospecies include Leptospira genomospecies 1 (two strains, serovars pinagchang and sichuan), Leptospira genomospecies 2 (six strains, serovars lushui, manhao 3, manzhuang, nanding, mengla and yunnan), Leptospira genomospecies 3 (one strain, serovar holland), Leptospira genomospecies 4 (one strain, serovar hualin) and Leptospira genomospecies 5 (one strain, serovar saopaulo). With the exception of Ballum, all serogroups with greater than one serovar studied were genetically heterogeneous. Phenotypic tests, including optimal growth temperature, lipase activity and growth inhibition by copper sulfate or 2,6-diaminopurine, were of little use in differentiating DNA relatedness groups. The name Leptospira alexanderi sp. nov. is proposed for Leptospira genomospecies 2 (type strain L 60T = ATCC 700520T, serovar manhao 3). (+info)
Antibiotic resistance of Escherichia coli isolated from poultry workers, patients and chicken in the eastern province of Saudi Arabia.
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The prevalence of antibiotic-resistant Escherichia coli isolates from faecal samples from 117 poultry industry workers, 100 patients and119 healthy chicken were compared. Resistance of E. coli chicken isolates to ampicillin, chloramphenicol, gentamicin, spectinomycin, tetracycline and trimethoprim + sulphamethoxazole (TMP + SMX) (range 57% - 99.1%) were significantly higher than those isolated from patients (range 21.9% - 71.4%) and workers (range 35% - 71.8%). However, for drugs not used in poultry, such as amoxicillin + cluvalanate (AMX + CLV), ceftazidime and nitrofurantoin, resistance rates of chicken isolates (range 0% - 2.6%) were significantly lower than those of patient isolates (range 8.7% - 30%). Resistance to spectinomycin reached 96% in E. coli chicken isolates and 71% in organisms isolated from humans. Use of this drug in Saudi Arabia is mostly limited to veterinary purposes. Multidrug resistance is alarmingly high in all groups but was highest in chicken isolates (77.4%). Serotyping of E. coli isolates showed that 27% of the organisms isolated from patients were overlapping with 10.9% of the chicken isolates, indicating the possibility of chicken being a source of the resistance pool for humans. We therefore call for the banning of antibiotics in the poultry industry as growth promoters and recommend that their use be restricted to treating infections. (+info)
Assessment of strain relatedness among Salmonella serotypes Salinatis, Duisburg, and Sandiego by biotyping, ribotyping, IS200 fingerprinting, and pulsed-field gel electrophoresis.
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Salinatis (antigenic formula, 4,12:d:eh:enz15) is a rare Salmonella serotype currently designated a triphasic variant of the diphasic serotype Duisburg (1,4,12,27:d:enz15) (underlining indicates that the O antigen is determined by phage lysogenization). Salinatis could also be related to serotype Sandiego (4,[5],12:eh:enz15), from which it might have been derived by loss of H-d flagellin genes. Nineteen Salmonella strains of serotypes Salinatis, Duisburg, and Sandiego were examined by biotyping, PvuII and SmaI ribotyping, IS200 fingerprinting, and pulsed-field gel electrophoretic profiling. Results from these methods, used alone or together, indicate that serotype Salinatis is more likely to be related to serotype Sandiego than to serotype Duisburg. For future lists of serotype names, it is recommended that Salinatis be considered a variant of Sandiego. (+info)
Molecular typing of Vibrio parahaemolyticus isolates, obtained from patients involved in food poisoning outbreaks in Taiwan, by random amplified polymorphic DNA analysis.
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Vibrio parahaemolyticus is one of the most important food-borne pathogens in Taiwan, Japan, and other countries with long coastlines. This paper reports on the development of a new random amplified polymorphic DNA (RAPD) method for the molecular typing of this pathogen. The 10-mer primer 284 (5'-CAG GCG CAC A-3') was selected to generate polymorphic amplification profiles of the genomic DNA at an annealing temperature of 38 degrees C. A total of 308 clinical isolates of V. parahaemolyticus collected during food poisoning outbreaks in Taiwan, mostly occurring between 1993 and 1995, plus 11 environmental and clinical reference strains were analyzed by this RAPD method. A total of 41 polymorphic RAPD patterns were recognized, and these patterns were arbitrarily grouped into 16 types (A to P). Types A, B, C, D, and E were the major types, and subtypes C3, C5, E1, B1, D2, and A2 were the major patterns. The major types were phylogenetically more closely related to each other than to any of the minor types. (+info)