内蒙古地区纹带棒杆菌临床分离株的耐药性及协同溶血活性

Antimicrobial resistance and cooperative hemolytic activity of Corynebacterium striatum isolates in Inner Mongolia region

目的了解内蒙古地区临床分离的纹带棒杆菌的耐药性及协同溶血活性,进一步认识其临床意义及致病性。方法2013年11月至2020年5月间,在内蒙古医科大学附属医院和内蒙古巴彦淖尔市人民医院住院患者送检临床样本中共分离500株纹带棒杆菌菌株,采用微量肉汤稀释法进行体外药敏试验,采用协同溶血试验检测纹带棒杆菌与金黄色葡萄球菌(ATCC 25923)和铜绿假单胞菌(ATCC 27853)的协同溶血活性。结果500株纹带棒杆菌分离株对青霉素、环丙沙星、头孢吡肟、复方磺胺甲唑、红霉素、亚胺培南和克林霉素等7种抗菌药物的耐药率均≥90.0%;对庆大霉素耐药率较低,为41.8%;对万古霉素和利奈唑胺均敏感。依据耐药表型进行分类,500株纹带棒杆菌分离株可划分为19个耐药表型,主要耐药表型为R1型(198株,39.6%),该型菌株对除万古霉素和利奈唑胺之外的所有测试抗菌药物均耐药或中介。500株菌株中分别有79.0%(395株)和78.6%(393株)的菌株与金黄色葡萄球菌和铜绿假单胞菌呈现协同溶血活性;与两类菌株协同溶血活性均为阳性的393株菌株耐药表型集中在R1~R5型,其中99.7%菌株呈现多重耐药表型。结论纹带棒杆菌临床分离株多为多重耐药株,仅对万古霉素和利奈唑胺敏感。大多数纹带棒杆菌可促进金黄色葡萄球菌和铜绿假单胞菌的溶血活性。临床样本中同时检出纹带棒杆菌、金黄色葡萄球菌和(或)铜绿假单胞菌时,要关注纹带棒杆菌的致病性。

Objective To investigate the antimicrobial resistance and cooperative hemolytic activity of clinical Corynebacterium striatum(C.striatum)isolates in Inner Mongolia region,so as to understand its clinical significance and pathogenicity.Methods A total of 500 strains of C.striatum were collected from clinical samples of inpatients admitted to Affiliated Hospital of Inner Mongolian Medical University and Bayannur People’s Hospital from November 2013 to May 2020.The antimicrobial susceptibility testing in vitro was performed by the broth microdilution method.Furthermore,the synergistic hemolytic activity of C.striatum with Staphylococcus aureus(S.aureus,ATCC 25923)and Pseudomonas aeruginosa(P.aeruginosa,ATCC 27853)was tested.Results The resistance rates of 500 strains of C.striatum to 7 kinds of antimicrobials were all above 90.0%,including penicillin,ciprofloxacin,cefepime,sulfamethoxazole-trimethoprim,erythromycin,imipenem and clindamycin.The resistance rate to gentamicin was relatively lower as to 41.8%.All of the C.striatum strains were sensitive to vancomycin and linezolid.According to the classification of drug-resistance phenotypes,500 strains of C.striatum were divided into 19 different phenotypes.The dominant resistance phenotype was R1 type(198 strains,39.6%),which was resistant or intermediate to all the antimicrobials except vancomycin and linezolid.Among 500 strains of C.striatum,395 strains(79.0%)and 393 strains(78.6%)showed synergistic hemolytic activities with S.aureus and P.aeruginosa,respectively.The resistance phenotypes of 393 strains showing synergistic hemolytic activity with both S.aureus and P.aeruginosa were mainly distributed among R1-R5 types.And 99.7%of the strains were multi-drug-resistant.Conclusions The clinical isolates of C.striatum are mostly multi-drug resistant and are sensitive to vancomycin and linezolid.Most of the C.striatum isolates can promote the hemolysis of S.aureus and P.aeruginosa.When C.striatum,S.aureus and P.aeruginosa are simultaneously detected in the same specimen,more attentions should be paid to the clinical significance and pathogenicity of C.striatum.