| Stenotrophomonas maltophilia(SMA)is an important pathogenic bacteria of nosocomial infection.Sulfonamides are the first choice in clinical infection.Because sulfonamides are widely used in human medicine,especially in animal breeding,the level of drug resistance of resistant bacteria is increasing,which endangers the effectiveness of clinical treatment of human medicine and the healthy development of animal breeding.In this paper,we investigated the similarity of sulfonamides resistance between pig derived SMA and human SMA in large-scale pig farms in Guizhou Province,and the prevalence of drug-resistant genes,and discussed the influence of sulfonamides on human SMA resistance.Objective to investigate the expression of Sul gene in SMA treated with different concentrations of sulfonamides for different times,and explore the molecular mechanism of SMA resistance and drug resistance,so as to provide help for finding ways to reduce SMA resistance and improve the success of infection treatment.1.In this study,236 strains of SMA were isolated from 11 large-scale pig farms in three regions of Guizhou Province by using selective culture and isolation combined with biochemical and molecular identification methods.The drug resistance of SMA was tested by broth dilution method recommended by CLSI.The results showed that the sensitivity rates of SMA from pigs to sulfamethoxazole,sulfamethoxazole,sulfadiazine,Sulfamethoxine,sulfamethazine and sulfathiazole were 23.4%,28.7%,1.8%,2.3%,1.8% and 2.9%,respectively;The sensitivity rates of human SMA to sulfamethoxazole,sulfamethoxazole,sulfadiazine,Sulfamethoxine,sulfamethazine and sulfathiazole were 16.9%,23.1%,16.9%,13.8%,13.8% and 13.8%,respectively;The sensitivity of human SMA to sulfadiazine,sulfamonomethoxine,sulfamethazine and sulfathiazole was higher than that of swine SMA.Since no animal specific sulfonamides have been used by pig farm workers,the resistance of human SMA to animal specific sulfonamides may come from pig derived SMA.2.PCR was used to detect the Sul 1,Sul 2 and sul 3 resistance genes of SMA.The results showed that the detection rate of Sul 2 was the highest(15.4%),and the detection rates of Sul 1 and sul 2 were 6.2%.The detection rate of all three drug-resistant genotypes was 6.2%;the most common type of drug-resistant genes was Sul 2 + Sul 3(21.5%);the next was Sul 1 + Sul 2(13.8%),and then Sul 1 + Sul 3(1.5%);29.2% did not carry the three resistance genes.The results showed that there was a positive correlation between the resistance rate of sulfanilamide gene and the detection rate of sulfonamides resistance gene.(P<0.05)The results showed that Sul 2 was the highest(11.1%),followed by Sul 1(8.2%)and sul 2(3.5%);the detection rate of all three drug-resistant genotypes was 33.9%;the most common type of two drug-resistant genes was Sul 2 + Sul 3(12.9%);the next was Sul 1 + Sul 3(10.5%)and sul 1 + Sul 2(5.3%);the detection rate of no three genotypes was 14.6%.The correlation analysis between drug resistance phenotype and drug resistance gene showed that the detection rate of sulfonamides resistance gene was positively correlated with the resistance to sulfanilamide.(P<0.05)3.Fluorescence quantitative PCR was used to investigate the transcription of sul1,sul2 and sul3 resistance genes in different growth stages and different concentrations of sulfadiazine.The results showed that the expression of sul1,sul2 and sul3 genes was inhibited at 8192 μ g / ml of sulfadiazine.In almost all growth stages,the peak expression of sul1 and sul2 was about 64 μ g / ml,and the expression levels of sul1 and sul2 at low concentrations were slightly higher than those at high concentrations.The relative expression rate of sul1 and sul2 was not as high as that of sul3 at different growth stages,which may indicate that sul3 gene is more sensitive to sulfonamides pressure than sul1 and sul2 genes.It is speculated that sul3 gene may have an important correlation with sulfonamides resistance. |
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