The Movable Resistance Genomic Island In Proteus Mirabilis

With Proteus mirabilis resistant isolates increased, the mechanism of antibiotic resistance become focus by researchers in recent years. As a bacterial mobile element encoding resistance, Salmonella genomic island 1, found in the P. mirabilis strains in 2007, which played an important role in transferring resistance genes. The purpose of this study was to determine the key mechanisms in horizontal transfer of antibiotic resistance genes in SGI1. P. mirabilis food and clinical isolates were examined for their susceptibility to 17 antibiotics and the presence of antibiotic resistance integrons?,?,?and gene cassette. After all the P. mirabilis isolates were genotyped by PFGE,the results were analyzed according to integrons?,?and gene cassettes. The SGI1s were detected in P. mirabilis isolates and their structures were analyzed. The results were as follows:P. mirabilis food and clinical isolates were detected by plate-culture and the tuf gene PCR methods, and the results of the both methods were in agreement. 14 P. mirabilis strains were isolated from food. The clinical isolates results of PCR and biochemical test were both consistent with the report from the samples donor the first Affiliated Hospital of Jinan University, indicating that the authenticity of P. mirabilis clinical isolates were proved. Forty-six P. mirabilis clinical isolates with multiple drug resistance in general, of which more than 10 kinds of antibiotic-resistant up to 69.6%. 14 P. mirabilis isolates from food were resistant to antibiotics, 28.6% resistant to 3~5 antibiotics. Chloramphenicol, tetracycline, erythromycin and cotrimoxazole were not suitable for infections caused by P. mirabilis in this region. The sensitive rate of ceftriaxone and cefoxitin were 88.3%~91.7%, indicating that the two antibiotics can be used for patients.Integron?was found in 34 (56.7%) P. mirabilis isolates, of which 4 isolates carring aadA2 and blaP1 gene cassettes, resistance to?-lactams and aminoglycosides; 19 isolates carrying dfrA17 and aadA5 gene cassettes, resistance to sulfonamides and aminoglycosides; 3 isolates carring blaP1, dfrA1 and aadB gene cassettes, respectively; 8 isolates carrying dfrA5 gene cassette. Integron?and dfrA1, sat2 and aadA1 gene cassettes were found in 17 (28.3%) P. mirabilis isolates, in which 16 (94.1%) isolates carring integron?and dfrA17 and aadA5 gene cassettes. Integron?and?were both found in 26.7% P. mirabilis isolates. Integron?was not detected in all isolates.The similarity value of 0.40 to 1.00 in 56 P. mirabilis isolates was shown by PFGE analysis. 12 groups, 42 P. mirabilis isolates had the same PFGE patterns, respectively, indicating that they may be the same clone strains. The value of Phylogenetic relationships of the isolates carring integron?and?was up to 0.72 to 1.00.Two P. mirabilis clinical isolates were detected to carry SGI1-B and SGI1-O, respectively. 4 P. mirabilis clinical isolates which might be clone to each other were detected to carry SGI1. 5 clinical isolates and 3 food isolates were found to carry a new SGI1 variant SGI1-U, and cloning for the same strain, suggesting that the possibility of SGI1-U horizontal transmission from food to human beings. SGI1, SGI1-B and SGI1-O were located between thdF and hipB genes, and SGI1-U was inserted between thdF and PMI3124 genes and the 8 isolates carring SGI1-U were detected missing hipA and hipB genes.In summary, many P. mirabilis isolates carried a variety of SGI1s and the results were useful to the study on epidemiology, bacterial multi-drug resistance mechanisms and dissemination.