Plasmid typing of Shigella sonnei epidemic strains and molecular relationship of their R-plasmids

Abstract

We conducted a surveillance program on epidemic and/or endemic Shigella strains in Asturias (Spain), their frequency and dispersion in our community, and their R-plasmids. We analyzed initial isolates of Shigella sonnei from two epidemic outbreaks using antibiotic resistance patterns and plasmid profile analysis as epidemiological markers. We found that the 2 outbreaks were caused by different S. sonnei strains, which respectively carried one and two R-plasmids together with other plasmids. The molecular relationship among these and three other R-plasmids from two S. sonnei strains isolated during a previous outbreak, were studied by restriction enzyme analysis and DNA-DNA hybridizations. We were able to establish different levels of relationship among the six R-plasmids.

Usefulness of ribotyping in a molecular epidemiology study of shigellosis

“…For the latter, the total number of unrelated strains considered was 38. The 8 organisms tested from the Oviedo outbreak were considered as 2 strains (0-I and 0-Il) which differed in their pattern of resistance, plasmid content [8,9] . The 13 clinical isolates and the reference strain CECT 585 of S.flexneri were also ribotyped using the 6 REs.…”

“…Even in industrialized countries where shigellosis is in decline its epidemiological surveillance continues to be important because: (1) As few as 100 organisms can lead to infection even in a well-nourished individual, hence, shigellas are among the most communicable bacterial agents of diarrhoeal disease. (2) The main infection sources are faecal contaminated food and water, being the cause of sporadic national or international epidemics and more frequently of small community outbreaks [8,9,[16][17][18][19][20][21][22]. The person-toperson spread is also a factor particularly in institutional outbreaks such as schools and nurseries [21].…”

“…None of these outbreaks took place in the Principality of Asturias, although in this region between 1982 and 1984 three water-borne outbreaks of S. sonnei shigellosis occurred in three localities with different water supplies and sewage facilities.The cases registered were about 1000 in the Oviedo outbreak [8], 65 in the Blimea outbreak and 250 in the Luanco outbreak [9] Organisms of S. flexneri, line XVII, seem to have been relatively frequent before 1986 but have not been found in the period following this year. On the other hand, line XXII includes organisms causing one sporadic episode of shigellosis registered in 1994, and the strain CECT 585 (NCTC 1) reputed to be the first case reported in France (Catalogue CECT).…”

Phage typing and drug resistance ofShigella sonneiisolated in England and Wales

“…This phage typing scheme is now used in several European countries including Sweden, Germany [5], Spain [6] and Italy [7]. In a survey of S. sonnei from Czechoslovakia [8], 83 % typability was reported with phage types 2 and 6 accounting for 34 % and 19 % respectively.…”

Molecular epidemiology of shigella infections in Israel

“…Plasmid profile analysis has been used in the differentiation of isolates belonging to S. sonnei and S. dysenteriae type 1 isolates, mostly during the investigation of outbreaks [5,6,7]. However the loss of plasmids due to long-term storage or numerous passages represents a serious drawback in this method [3,8,9].…”