Rapid Detection Of Enteropathogenic Bacteria And The Drug-resistance Of Staphylococcus Aureus Based On Surface-Enhanced Raman Scattering

Human health is seriously threatened by the bacterial infections throughout the world.Antibiotics are commonly used drugs for the treatment of bacterial diseases.Recently,the bacterial resistance has become a hot issue in the biomedical fields because of the excessive abuse of antibiotics.Therefore,there is an urgent need to develop the accurate and rapid detection method for monitoring and identification of resistant bacteria in the clinical treatment.As a biometric fingerprinting technique,surface enhanced Raman scattering（SERS）has opened a new research perspective for the rapid and accurate detection of pathogenic bacteria in recent years.In this study,a portable Raman spectrometer had been applied for rapid detection of single and mixture pathogenic bacterial contamination by applying Au nanoparticles sol as enhanced substrate.The results indicated that Escherichia coli,Salmonella typhimirium,Shigella flexner and Staphylococcus aureus showed specific Raman phenotypes at 600～1700 cm^-1.Generally,different bacteria could be easily and instantly recognized by its Raman phenotypes.The PC-LDA classification model was set up by combined bacterial Raman phenotypes with the multivariate statistical analysis.With the short-time inoculation,four enteropathogenic bacteria could be rapidly,precisely,sensitively and specifically identified.Furthermore,the model also had a good ability to predict the mixed contamination and the accuracy rate could reach 100%.Dynamic and rapid identification of bacterial resistance is the basis for identifying drug-resistant bacteria and their resistance mechanisms.In this study,the uses of oxazolin and cefazolin on sensitive S.aureus in order to induce and screen the drug-resistant strains.The identification and methodlogical validation of bacterial resistance were accomplished by MIC,drug sensitive disk,PCR,SERS and the laser confocal Raman microscopy.The results showed that:（1）The drug-resistant strains of S.aureus were all multidrug-resistant bacteria.The producation of bacterial resistance is a dynamic accumulation process.The resistance spectra of Staphylococcus aureus induced by different drugs were also different from each other.（2）A rapid SERS method for the identification of drug-sensitive bacteria and drug-resistant bacteria was established.The drug-sensitive and resistant bacteria were significantly different in the characteristic band range of 636～1300 cm^-1.The peak intensity of S.aureus ATCC 29213 was stronger than the OX-S.aureus and KZ-S.aureus.LDA and PCA were established by this characteristic band and the results show that the accuracy rate can reach 100%,which indicates that the model has a high reliability.（3）Take the ratio of peak intensity between the characteristic peaks and MIC as targets,two corresponding identification model was established to predict the sensitivity of S.aureus to antimicrobial agents（oxazolin and cefazolin）and the dynamic monitoring of the process.This will provide the theoretical and technical support for clinically accurate medication.（4）The established SERS method was validated by using the laser confocal Raman microscopy and PCR technology.The result is further proved the validity and reliablilty of the SERS method for the rapid identification of drug-sensitive and resistant bacteria.The results show that SERS technology has great potential in identifying pathogenic bacteria and its drug-resistance.The qualitative analysis model based on SERS has high accuracy and high sensitivity.It provides an important basis for the application and popularization of SERS in the clinical rapid diagnosis of pathogenic microbial resistance.