Plasmid profiles of antibiotic-resistant<i>Shigella dysenteriae</i>types 2, 3, 4, 6 and 7 isolated in Ethiopia during 1976–85

Gebre-Yohannes, A; Drašar, B. S.

doi:10.1017/s0950268800047658

Cited by 10 publications

(7 citation statements)

References 23 publications

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“…It was also shown elsewhere that the core plasmids (140, 6, and 2 MDa) were present in both the epidemic and nonepidemic isolates of S. dysenteriae type 1, which correlated with the results of our study. Other than type 1, no study has yet been performed on plasmid profiles of other S. dysenteriae serotypes, except for a study in Ethiopia which focused on plasmid-mediated antibiotic resistance (4,5). This is the first report on the diversity of plasmid profiles of different serotypes of S. dysenteriae, which we believe will provide useful insights into the epidemiology of this organism in Bangladesh.…”

Section: Discussionmentioning

confidence: 99%

Temporal Shifts in the Dominance of Serotypes of Shigella dysenteriae from 1999 to 2002 in Dhaka, Bangladesh

et al. 2003

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A total of 358 Shigella dysenteriae strains isolated from patients attending the Dhaka treatment center of the International Centre for Diarrheal Disease Research, Bangladesh, between the years 1999 and 2002 were included in this study. S. dysenteriae type 1, the dominant serotype in 1999 (76.4%), declined to 6.5% in 2002. On the other hand, S. dysenteriae types 2 to 12 were isolated with increasing frequencies of 19, 67, 73.5, and 87% in 1999, 2000, 2001, and 2002, respectively. Of these, types 2 and 4 were the most dominant serotypes, accounting for more than 18.7 and 28.5% of the total isolates, respectively. There was no isolation of serotypes 5, 7, 8, and 13 during this period. Twenty-eight (7.8%) of the isolates were atypical and agglutinated only with the polyvalent antiserum of S. dysenteriae. More than 98% of type 1 strains isolated between 1999 and 2001 were resistant to ampicillin, sulfamethoxazole-trimethoprim, and nalidixic acid. Among other serotypes of S. dysenteriae, Nal r type 2 strains were isolated in 2001 and 2002. Although heterogeneous plasmid profiles were obtained depending on the presence or absence of a single plasmid, core plasmids were defined for particular serotypes. On the other hand, the same plasmid profile was found to be shared by different serotypes. Interestingly, plasmid patterns of types 2 and 4 were almost identical except that a middle-range plasmid of 70 to 60 MDa was present in type 4 in addition to the core plasmids. All the strains harboring the 140-MDa plasmid were positive for the ipaH gene, had Congo red binding abilities, and were positive by the Sereny test, demonstrating their invasive properties.Shigellosis is one of the major diarrheal diseases afflicting humans in the developing and underdeveloped parts of the world, especially Bangladesh. Shigellosis produces inflammatory reactions and ulceration on the intestinal epithelium followed by bloody diarrhea and mucus in the stool. Shigellosis is endemic in Bangladesh, and it is estimated that dysentery accounts for 20% of deaths related to diarrhea among children (32). The genus Shigella, the causative agent of shigellosis, is comprised of four species, namely, S. flexneri, S. dysenteriae, S. boydii, and S. sonnei, and each of these species is further classified into 15 (including subtypes), 13, 18, and 1 serotypes, respectively, based on the O antigen component of lipopolysaccharide present on the outer membrane of the cell wall. S. flexneri and S. dysenteriae are the major concerns for developing countries. The manifestation of S. dysenteriae type 1 infection is more severe because of its capacity to produce Shiga toxin, which is exclusively produced by this type. Clinical infection can be transmitted by as few as 10 Shigella organisms (3), even without neutralization of gastric acid.At least three periods of epidemic outbreaks of dysentery due to S. dysenteriae 1 have been recorded previously in the Indian subcontinent, in 1972-1973, 1983-1984, and 1993-1994 (1, 9, 18, 24). Despite improvement of municipal wa...

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Section: Discussionmentioning

confidence: 99%

Temporal Shifts in the Dominance of Serotypes of Shigella dysenteriae from 1999 to 2002 in Dhaka, Bangladesh

et al. 2003

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“…In many cases, resistance genes are found to reside on easily transferable R plasmids. However, chromosomally borne resistance genes have recently been identified in a number of studies (10,15,29,41,42), although the basis of chromosomal resistance has not been widely investigated.…”

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Nested Deletions of the SRL Pathogenicity Island of Shigella flexneri 2a

et al. 2001

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In this study, we determined the boundaries of a 99-kb deletable element of Shigella flexneri 2a strain YSH6000. The element, designated the multiple-antibiotic resistance deletable element (MRDE), had recently been found to contain a 66-kb pathogenicity island (PAI)-like element (designated the SRL PAI) which carries the Shigella resistance locus (SRL), encoding resistance determinants to streptomycin, ampicillin, chloramphenicol, and tetracycline. The YSH6000 MRDE was found to be flanked by two identical IS91 elements present at the S. flexneri homologs of the Escherichia coli genes putA and mdoA on NotI fragment D. Sequence data from two YSH6000-derived MRDE deletants, YSH6000T and S2430, revealed that deletion of the MRDE occurred between the two flanking IS91 elements, resulting in a single IS91 element spanning the two original IS91 loci. Selection for the loss of tetracycline resistance confirmed that the MRDE deletion occurred reproducibly from the same chromosomal site and also showed that the SRL PAI and the SRL itself were capable of independent deletion from the chromosome, thus revealing a unique set of nested deletions. The excision frequency of the SRL PAI was estimated to be 10 ؊5 per cell in the wild type, and mutation of a P4-like integrase gene (int) at the left end of the SRL PAI revealed that int mediates precise deletion of the PAI.

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“…of major clinical significance is the high prevalence of antibiotic multiresistant strains. Most of these strains harbour easily mobilisable resistance plasmids [2 1,221, but strains exhibiting non-transferable, possibly chromosomally located resistance genes have been identified [23]. However, no molecular studies have been performed to elucidate the basis of chromosomal resistance.…”

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A spontaneous 99-kb chromosomal deletion results in multi-antibiotic susceptibility and an attenuation of contact haemolysis in Shigella flexneri 2a

Rajakumar

Sasakawa

Adler

1996

Journal of Medical Microbiology

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A Tn5-generated mutant (strain S2430) of Shigella flexneri 2a (strain YSH6000) exhibited attenuated virulence and, in addition to the Tn5 insertion in the SalI K fragment of its virulence plasmid, had a 99-kb deletion within its chromosome. Unlike its wild-type parent, strain S2430 was susceptible to ampicillin, streptomycin, tetracycline and chloramphenicol. An independent multi-antibiotic susceptible variant of strain YSH6000 had a similar deletion. Southern blot analysis of pulsed field electrophoresis gels enabled the sizing of this deletion and its mapping to a region of the chromosome on Not1 fragment D bounded by the S. flexneri homologues of ompA and pyrC. Hybridisation experiments with a probe specific to the multi-antibiotic resistance region indicated that this large deletion was responsible for antibiotic susceptibility. Both strain S2430 and a derivative of the antibiotic-susceptible variant, with a Tn5 insertion in its SalI K fragment, exhibited an equal reduction in contact haemolysis compared with the Tn5-bearing derivative of strain YSH6000. However, strain S2430 alone clearly displayed delayed plaque forming ability in LLC-MK2 monolayers, suggesting that the two examples of this deletion may not be identical.

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Plasmid profiles of antibiotic-resistantShigella dysenteriaetypes 2, 3, 4, 6 and 7 isolated in Ethiopia during 1976–85

Cited by 10 publications

References 23 publications

Temporal Shifts in the Dominance of Serotypes of Shigella dysenteriae from 1999 to 2002 in Dhaka, Bangladesh

Temporal Shifts in the Dominance of Serotypes of Shigella dysenteriae from 1999 to 2002 in Dhaka, Bangladesh

Nested Deletions of the SRL Pathogenicity Island of Shigella flexneri 2a

A spontaneous 99-kb chromosomal deletion results in multi-antibiotic susceptibility and an attenuation of contact haemolysis in Shigella flexneri 2a

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