Mechanism Of Drug Resistance To Macrolides In The Streptococcus Anginosus Group And Analysis Of Clinical Infection Characteristics

Objective This study aims to analyze clinical infection characteristics and drug resistance of the Streptococcus anginosus Group,and preliminary studyi ng macrolides and lincosamides resistant mechanism may exist,understandin g the Streptococcus anginosus Group of molecular epidemiology mechanism in Ning Xia,as to provide theoretical basis for clinical diagnosis and guidin g clinical rational use of antibiotics.Methods Strains of the Streptococcus anginosus Group were collected from patients admitted to the hospital in Ning Xia from January 2017 to Septembe r 2018,the type,source,infection characteristics and drug susceptibility res ults of the strains were analyzed using the software WHONET2018.MALDITOF MS was used to identify the Streptococcus anginosus Group to species,and 16 S r RNA and sod A gene sequencing were performed to confirm the r esults,and the specificity of the detection method was compared.Disk Diffus ion Test(K-B method)and E-test were used to detect its drug sensitivity,a nd macrolide drug resistance genes erm A,erm B,mef A and lincoamide drug resistance genes lnu A,lnu B,lnu C and lnu H were tested to preliminarily und erstand its possible drug resistance mechanism.Results Clinical specimens were isolated from 224 strains of the Streptococ cus anginosus Group,including 138 strains of the Streptococcus constellans,76 strains of the Streptococcus anginosus,and 10 strains of the Streptococ cus intermadius,accounting for 61.8%,33.8% and 4.4%.The most common s pecimens were respiratory tract specimens,purulent secretions and drainage fluid,accounting for 34.8%,33.5% and 11.2%.The most common diseases c aused by the Streptococcus anginosus Group were respiratory tract infection,suppurative infection and bloodstream infection,accounting for 34.8%,33.5% and 8.5%.Strains of the Streptococcus anginosus Group combined with other strains accounted for 39.1%,and Enterobacteriaceae Bacteria were co mmon.Three strains of clinical infectious diseases,are predominantly male p atients,mostly in elderly patients,the Streptococcus anginosus is given prio rity to respiratory specimens,the Streptococcus constellans is given from re spiratory tract specimens and purulent secretion specimens,the Streptococcus intermadius is given priority to purulent secretion specimens,whicn are co mmon in the emergency department,the Streptococcus constellans and the Streptococcus anginosus exist differences in the pyogenic infection obviously.(P < 0.05).The resistance rate of the Streptococcus anginosus Group to ma crolides(erythromycin)and lincoamides(clindamycin)was higher than 50%,and the sensitivity rate to cephalosporins and penicillin drugs was higher t han 80%.The identification results from sod A were used as the standard,a nd 16 S r RNA could be used to identify the strains of the Streptococcus ang inosus Group to the species.MALDI-TOF MS was more specific for the ide ntification of the Streptococcus constellans.After screening 224 strains of ba cteria,180 strains of bacteria were subjected to D-test and drug resistance gene amplification.No positive D-test results were found.104 strains of erm B(+)were found,among which three strains showed simultaneous erm A(+),all of which showed erythromycin resistance.mef A and erm B genes were f ound in both erythromycin resistant and clindamycin sensitive strains,while one strain only had mef A gene.Among the 48 erythromycin sensitive strains,13 erm B(+)strains were detected,which did not conform to the drug-sens itive phenotype.lnu A,lnu B,lnu C and lnu E resistance genes were amplified i n 145 clindamycin-resistant strains,but only one positive strain was found.Conclusions1?In this study,Streptococcus anginosus Group mostly caused respiratory tr act infection and suppurative infection,and the clinical manifestations weren ot specific.2?Streptococcus anginosus Group showed a high rate of resistance to macr olides and lincomylamides,among which resistance to erythromycin may be related to erm B gene,and a small amount of erm A and mef A exist.Only 1case of lnu B gene was detected in lincomylamide resistant strains,and the rest were not detected,which may have other drug resistance mechanisms.3?Among the identification methods for the Streptococcus anginosus Group,the MAIDI-TOF MS technique can rapidly identify the strains of streptococ cus yanistidis to species.