Widespread occurrence of specific restriction endonucleases in Salmonella infantis, Salmonella thompson, and Salmonella blockley isolated from humans in Japan

Emergence ofSalmonellaBlockley, possible association with long-term reactive arthritis, and antimicrobial resistance

We previously reported the case of a patient who became ill with Salmonella serotype Blockley after eating a chicken meal and who was still suffering symptoms of salmonella-reactive arthritis 10 years after the initial infection. The immunological consequences of infection were of concern and prompted a literature review because of the possibility that Salmonella Blockley may be more likely to cause long-term illness in certain patients than more common serovars. The review revealed the additional cause for concern of plasmid-borne extended spectrum beta-lactamases and the high frequency of integron-associated multidrug resistance in some isolates. The serovar was described in 1955 in the USA and Europe. It has become common in South East Asia and recently has been reported more often in Europe. A review of reactive arthritis outbreaks shows that information on the incidence and duration of the condition caused by serovars other than Salmonella serotype Enteritidis and Salmonella serotype Typhimurium is very limited. Rheumatologists can assist microbiologists and epidemiologists by reporting relevant cases of long-term reactive arthritis.

Identification of a DNA restriction-modification system in Pectobacterium carotovorum strains isolated from Poland

AIMS

Polish isolates of pectinolytic bacteria from the species Pectobacterium carotovorum were screened for the presence of a DNA restriction-modification (R-M) system.

METHODS AND RESULTS

Eighty-nine strains of P. carotovorum were isolated from infected potato plants. Sixty-six strains belonged to P. carotovorum ssp. atrosepticum and 23 to P. carotovorum ssp. carotovorum. The presence of restriction enzyme Pca17AI, which is an isoschizomer of EcoRII endonuclease, was observed in all isolates of P. c. atrosepticum but not in P. c. carotovorum. The biochemical properties, PCR amplification, and sequences of the Pca17AI restriction endonuclease and methyltransferase genes were compared with the prototype EcoRII R-M system genes. Only when DNA isolated from cells of P. c. atrosepticum was used as a template, amplification of a 680 bp homologous to the gene coding EcoRII endonuclease.

CONCLUSIONS

Endonuclease Pca17AI, having a relatively low temperature optimum, was identified. PCR amplification revealed that the nucleotide sequence of genes for EcoRII and Pca17AI R-M are different. Dcm methylation was observed in all strains of Pectobacterium and other Erwinia species tested. The sequence of a DNA fragment coding Dcm methylase in P. carotovorum was different from that of Escherichia coli.

SIGNIFICANCE AND IMPACT OF THE STUDY

Pca17AI is the first psychrophilic isoschizomer of EcoRII endonuclease. The presence of specific Dcm methylation in chromosomal DNA isolated from P. carotovorum is described for the first time. A 680 bp PCR product, unique for P. c. atrosepticum strains, could serve as a molecular marker for detection of these bacteria in environmental samples.

Isolation and characterization of new restriction endonucleases from Vibrio parahaemolyticus: VpaK32I enzyme with the class-IIS heptanucleotide specificity, GCTCTTCN1/N4

Six restriction endonucleases (ENases), classified into four different specificities, were found in a screen among 68 reference strains of Vibrio parahaemolyticus of human origin. Five of these ENases are isoschizomers of well-known ENases, while the remaining one, designated VpaK32I, is a novel and highly efficient class-IIS ENase with the hepatanucleotide recognition site, 5'-GCTCTTC(1/4)-3'.