ABSTRACT
Horizontal gene transfer contributes to the spread of antibiotic-resistance cassettes, the distribution of toxin-encoding phages and the transfer of pathogenicity islands. Natural transformation, which is the process of competent cells to uptake free DNA from environment and to recombine this DNA into the chromosome, is a mode of horizontal gene transfer. Natural transformation promotes the spread of antibiotic-resistance cassettes among different bacteria, resulting in the emergence of antibiotic resistant bacteria. The emergence of antibiotic resistant pathogens poses an enormous threat to the treatment of infections. Natural transformation could occur in many bacteria, but the mechanism many be different in different bacteria. Also, the inducer and efficiency of natural transformation in different bacteria are influenced by various factors. This review focuses on the mechanism and influencing factors of natural transformation in bacteria.
ABSTRACT
We investigated the antibiotic‐resistant genes and genetic diversity of Pseudomonas aeruginosa from patients in hospital ,the smear samples from hospital and clinic environment ,and from medical staff’ hands respectively in 2011‐2012 in Nanshan District of Shenzhen .Polymerase chain reaction were used to detect the 20 kinds of antibiotic‐resistant genes (TEM , VEB,CARB,OXA,SHV,PER,GES,GTX,SPM,GIM,IMP,VIM,DHA,oprD,Aac(6′)‐Ⅰ ,Aac(6′)‐Ⅱ ,Aac (3′)‐Ⅰ ,A ac(2″)‐Ⅰ ,qacE1‐sull and int‐Ⅰ) .Multilocus sequencing typing was used to analyze the clonal complexes .The 11 kinds resistant genes TEM ,SHV ,IMP ,DHA ,Aac(6′)‐Ⅰ ,Aac(6′)‐Ⅱ ,Aac(3′)‐Ⅰ ,Aac(2″)‐Ⅰ ,qacE1‐sull ,int‐Ⅰand oprD were detected ,for the positive rates respectively ,and which were 8 .1% ,6 .4% ,4 .8% ,9 .7% ,4 .8% ,14 .5% ,9 .7% , 56 .5% ,8 .1% ,and 8 .1% ;the loss rate of oprD gene was 61 .2% .The 19 antibiotic resistance gene profiles existed in 52 Pseudomonas aeruginosa strains .Multilocus sequencing typing found 39 sequence types and 5 clonal complexes in 62 Pseudo‐monas aeruginosa strains ,CC244 and ST856 were dominant .There were some differences of antibiotic resistance gene profiles between different samples ,the Pseudomonas aeruginosa strains from patients carried multiple resistant genes .In our research , the Pseudomonas aeruginosa had the genetic diversity and the dominant clonal complexes existed .
ABSTRACT
OBJECTIVE To study the epidemiology of the drug-resistant genes in meticillin-resistant coagulase negative staphylococcus(MRCNS).METHODS mecA,aac(6′)/aph(2″) and aph(3′)-Ⅲgenes of aminoglycoside-modifying enzyme(AME) and ermA/B/C genes of erythromycin methyltransferase were detected by polymerase chain reaction(PCR) from 40 MRCNS strains.RESULTS Thirty-nine strains carried mecA gene,32 strains with aac(6′)/aph(2″) gene,15 strains with aph(3′)-Ⅲ gene,30 strains with ermA/B/C gene and 2 strains with tetM gene in 40 MRCNS strains.CONCLUSIONS About 65% MRCNS strains carry mecA,aac(6′)/aph(2″),/aph(3′)-Ⅲ and ermA/B/C genes at the same time.