Instability of multiple drug resistance plasmids inSalmonella typhimuriumisolated from poultry

Abstract

SUMMARYPlasmids in five strains of Salmonella typhimurium resistant to ampicillin, chloramphenicol, gentamicin, neomycin/kanamycin, streptomycin, sulphonamides, tetracyclines and trimethoprim (ACGKSSuTTm), CGKSSuTTm, ACSSuT or CSSuT which had been isolated from poultry in the first 3 months of 1989 have been characterized and compared with plasmids in two strains of R-types ACGKSSuTTm and ASSuTTm isolated from two patients later in the year. With the exception of the human isolate of R-type ASSuTTm, all strains carried two non-conjugative plasmids, one coding for SSu and belonging to incompatibility group Q, and a second coding for multiple resistance and belonging to the Flme

Occurrence of FImeplasmids in multiply antimicrobial-resistantEscherichia coliisolated from urinary tract infection

“…The johannesburg [29], in S. wien [30] and more recently, in untypable strains of S. typhimurium isolated in England [8], the coefficients of similarity between related plasmids remained in excess of 60% [8]. In this study, with the exception of pDEP37, pDEP38 and pDEP40, the coefficients of similarity between pDEP10 and the remaining F1me plasmids were less than 50 %, which is considerably less than has been observed from evolutionary divergence within a single F1me plasmid type.…”

“…The strains examined by Colonna and colleagues [27] were all clonal derivatives of either epidemic S. wien or epidemic S. typhimurium and were consequently very similar. Furthermore, it is known that the genes coding for aerobactin production and drug resistance can be spontaneously lost from Flme plasmids [8]. The finding of IS1 elements flanking the aerobactin iron-uptake system has led to the suggestion that a composite transposon may have facilitated the dissemination of the aerobactin system [27].…”

“…Fime plasmids were first identified in multiply drug-resistant Salmonella typhimurium of Middle Eastern origin [3,4] and have subsequently been identified in epidemic strains of S. wien and S. typhimturium which have been commonly associated with severe infections in paediatric hospitals in developing countries [5,6], in sporadic drug-resistant isolates of S. typhi [7] and more recently, in strains of S. typhimurium isolated from turkeys and chickens in England [8]. However, before the outbreak of E. coli 015 K52 HI in 1986, this plasmid group had not been described in E. coli.…”

Partial characterization of a genomic island associated with the multidrug resistance region of Salmonella enterica Typhymurium DT104

“…It has been suggested that the chromosomal integration of resistance genes may result in a stable structure which may persist even in the absence of selective pressure [23]. Attempts to transfer the MDR phenotype of S. enterica Typhymurium DT104 to strains of E. coli have been unsuccessful [24], which provides support for this hypothesis.…”

Diversity of Strains of Salmonella enterica Serotype Enteritidis from English Poultry Farms Assessed by Multiple Genetic Fingerprinting

“…The present study, in agreement with previous experiments (11), found that the vast majority of serovar Enteritidis strains carry just the serospecific virulence plasmid. Extrachromosomal DNA is regarded as an unstable genetic marker (2,5). Also, it is recognized that strains with the same chromosomal features may show different plasmid restriction patterns (28) and that the same plasmid profile may be present in strains which are different at a chromosomal level (24).…”