The enterobacteria from this study were isolated from samples collected in four different types of origin. Among the total bacterial isolates, 40% are from human clinic, 20% from animal clinic, 10% from human hospital environment and 30% from veterinary hospital environment.
This study of antimicrobial resistance in enterobacteria characterized a phenotypic profile of resistance to beta-lactam antibiotics, in which among the 70 bacterial samples studied, 52 (74.28%) were resistant to ampicillin, 44 (62.85%) were resistant to amoxicillin associated with the beta-lactamase inhibitor clavalunate, 38 (54.28%) were resistant to cefazolin, and 6 (8.57%) were resistant to cefuroxime. The Table 2 shows the percentage of antimicrobial resistance by sample source of Enterobacteriaceae.
Phenotypically, through the antibiogram method, the species E. aerogenes, E. agglomerans and C. neteri stand out exhibiting the highest rate of resistance, being resistant to 10 of the 11 antibiotics tested (90.9%).
The MDR, XDR and PDR profiles, found phenotypically in this study, determined that among the enterobacteria studied here there was a predominance of 68.57% XDR profiles, in which there was sensitivity to at least two groups among the four that form the β- lactams. These data can be observed in Figure 1.
Fortunately no PDR profile was found because no bacteria were resistant to all antibiotics but because the acquisition of antimicrobial resistance is a natural phenomenon and can be accentuated by other factors, it should not be ruled out that they may present new profiles in the future including the PDR profile.
Still on the phenotypic profiles, it was observed that 28.57% were MDR and that the penicillin group was the antibiotic for which there was the highest resistance rate. There was resistance to at least one of the penicillins studied here in approximately 85.71% of the bacteria. For cephalosporins, there was resistance to at least one of those tested here in 77.14% of bacteria, a relatively high number demonstrating that such drugs, from the first to the fourth generation, are also losing their effect on enterobacteria.
In relation to β-lactams used as drugs of last resource- carbapenems - in this study there was phenotypic resistance to imipenem in 35.71% of the isolated bacteria. The antibiotic that presented the lowest percentage of resistance was the monobactam aztreonam with a resistance rate of 34.28%, which corresponds to a rate close to that of carbapenems, showing that these antibiotics were the most effective against most bacterial samples studied.
The specie E. agglomerans showed phenotypic resistance data with profiles ranging from completely sensitive to XDR. This shows that within a same bacterial specie the resistance possibilities are very variable.
Following the analyzes of the results of this work, the mechanism of greatest strength that has been the ESBL (17.14%), while the others were: AmpC (4.2%), MBL (1.4%) and Carbapenemase (0%). The specie Y. ruckeri, was the one that promoted more number of mechanisms (ESBL, MBL and AmpC). The species that did not present any of the mechanisms were: E. blattae, H. alvei, R. terrigena and C. freundii.
The percentages of amplification of the beta-lactamase genes, through the qPCR method, found among Enterobacteriaceae were: 66.66% for the blaGIM and blaSIM genes, 61.11% for the blaDHA and blaTEM genes, 55.55% for the blaCMY, blaCTX-M, blaNDM, blaOXA genes, 50% for the blaIMP gene, 44.44% for the blaSHV and blaSPM genes, 38.88% for the blaKPC gene, 33.33% for the blaSME gene and 16.66% for the blaVIM gene.
The fenotypic profile of resistance to beta-lactam antimicrobials was determined in 19 bacterial species among enterobactérias: among all the phenotypic resistances found, the species E. aerogenes, E. agglomerans, C. freundii and C. neteri, stood out showing the highest resistance rate (90.9%). The molecular profile of resistance to beta-lactam antimicrobials was determined in 18 bacterial species among enterobacteria: 94.44% showing resistance for aztreonam, ceftazidima, cefoxitin and piperacillin associated with beta-lactamase inhibitor tazobactam. Phenotypic and molecular data are compared in Table 4.
By analyzing the amplification rate of the genes that confer beta-lactam resistance and making an association of the same with the literature review carried out in this study, it was observed that the species that showed potential for resistance of a greater number of antibiotics were: E aerogenes, R. terrigena, M. morganii, E. ictaluri, C. neteri, S. paratyphi and Y. ruckeri.,, exhibiting resistance potential for all antibiotics (100%) tested. C. freundii, Klebsiella spp., E. coli, E blattae, P. rustigiani and E. persicina were studied, showing resistance potential for 10 of the 11 antibiotics (90.9%) tested.
The resistance information obtained in this study shows that 100% of the analyzed species present a high potential for resistance to several beta-lactams. Among the potential profiles suggested by the qPCR analyzes, the XDR and PDR data were, respectively, 67,14% and 32,8% among the studied species. These data can be observed in Figure 1.
In molecular analyzes, PDR should be considered. The rate found for these pages was 38.88% and, although not very high, has repercussion on the degree to a clinical problem that may represent for the population.
The Pearson coefficient was calculated to linearly correlate two variables. The Pearson correlation coefficient varies between –1 and 1. The signal indicates the direction of correlation (negative or positive) while the value indicates the magnitude. The closer to 1 the stronger the level of linear association between variables 3.
In this study the detection rate of antimicrobial resistance by molecular methodology was generally higher than the detection rate by phenotypic methodology. But as already mentioned, the mere presence of the resistance gene in the bacterial genome does not necessarily imply its expression, and the phenotypic methodology is still necessary.
Were done a experiment to verify the plasmid perfil, and from plasmid DNA digested were no identifyed sites to EcoR I and Hind III restriction enzymes. After these results the authors decided that the best experiment to observe the restriction plasmid profile must be the sequencing experiments that will be done in another study.