The differences in conjugation frequencies among pA/C + pX1 and pX1::CMY transconjugants with those of pX1, led us to determine that the transposition and co-integration events occurred within YU39 at frequencies ranging between 10-6 and 10-9, which were in the range of those reported for other transposition or co-integration events [18, 43, 44]. These results indicated that the first round conjugation frequencies combined the low frequency of co-integration or transposition VX-689 manufacturer with the high frequency of conjugation of pX1 (Table 5); while the second round conjugations directly measured the conjugation frequencies of pA/C + pX1 or pX1::CMY, which were high in most of
the cases due to the use of the pX1 conjugative machinery
(Table 3 and Table 4). trans-mobilization of pColE1-like The mobilization capacities of ColE1 related plasmids have been recognized for decades, and plasmids from several incompatibility groups have been shown to mobilize them [46]. ColE1-like plasmids are prevalent in Salmonella serovars [11], and most of them carry the Km resistance gene aph[47, 48]. The YU39 pColE1-like did not confer Km resistance nor to any other of the YU39 antibiotic resistances tested (data not shown). Despite the high frequency of transfer of the pColE1-like plasmids, our hybridization assays demonstrated that this plasmid was not involved in the genetic re-arrangements displayed by pA/C and pX1, or the acquisition of the bla CMY-2 gene. Taken together, these results suggest that pColE1-like is a www.selleckchem.com/products/NVP-AUY922.html very efficient molecular parasite. However, only the determination of its complete nucleotide sequence could provide information Napabucasin in vitro regarding the presence of a gene increasing the fitness of its host bacteria. Epidemiological implications Our study demonstrated that pSTV and pA/C can indeed co-exist within E. coli and Typhimurium strains. Therefore, our original epidemiological observations that each of these plasmids was restricted to distinct genotypes [4] cannot Suplatast tosilate be explained by negative interactions between them. In our previous studies
we showed that the only strain capable of conjugative transfer of bla CMY-2 was YU39 [5]. We screened the Mexican population for the presence of pX1, but YU39 was the only positive strain (data not shown), explaining why the other ST213 pA/C lacked the capacity to be transferred. We hypothesize that pA/C emerged in ST213, which is a genotype lacking pSTV, and that the non-conjugative pA/C failed to colonize ST19 strains. The widespread dissemination of pA/C and bla CMY-2 in the ST213 population by the action of YU39 pX1 is a rare, but not negligible, event. Future epidemiological studies designed to track the prevalence of pX1 in the Mexican populations will shed light on these interactions.