Analysis for correlation between drug resistance and positive pattern of virulence genes in Acinetobacter baumannii / 临床检验杂志

ABSTRACT

Objective@#To investigate the drug resistance and positive virulence genes of Acinetobacter baumannii (A.baumannii) and analyze the correlation between drug resistance and the positive pattern of virulence genes. @*Methods@#A total of 67 strains of A.baumannii were collected and identified by matrix assisted laser desorption ionization time of flight mass spectrometry technology (MALDI-TOF MS). Drug susceptibility tests were carried out by turbidimetric and redox indicator method. The homology of A.baumannii stains was explored by cluster analysis. The 8 virulence genes including bacterial outer membrane protein (ompA), biofilm formation (adeH, csuA, pgaA), iron uptake system (basJ), phospholipase D (plcD), capsular positive phenotype (ptk) and regulation of quorum sensing system (abaI) were amplified by PCR and sequenced. The correlation between virulence genes and drug resistance in the 67 strains of A. baumannii was investigated. @*Results@#The positive rates of virulence genes ompA, adeH, csuA, pgaA, abaI, basJ, ptk and plcD were 94%, 100%, 94%, 99%, 93%, 96%, 82% and 99%, respectively. Among the 67 strains of A. baumannii, 3 genes were simultaneously detectable in 1 strain (1.5%), 5 genes were positive in 2 strains (3.0%), 6 genes were positive in 2 strains (3.0%), 7 genes were positive in 14 strains (20.9%) and all the 8 genes were positive in 48 strains (71.6%). Among the 48 strains with 8 positive virulence genes, the drug resistance rate of polymyxin was only 2.1%, but tetracycline was 58.2%, piperacillin and other 13 antibiotics was more than 80%. The 14 strains with 7 positive virulence genes showed more than 78% of resistance rate for all the tested antibiotics except for tetracycline and polymyxin. Cluster analysis showed that the 67 strains of A. baumannii were divided into 2 genotypes A (41 strains) and B (26 strains). The 41 strains of A type were divided into A1 (27 strains) and A2 (14 strains) subtypes. The strains of A1 subtype were mainly from neurosurgery department (7 strains), ICU (5 strains) and pneumology department (3 strains). The strains of A2 subtype were mainly from pneumology department (3 strains), cardiothoracic surgery department (3 strains), ICU (2 strains) and neurosurgery department (2 strains). The 26 strains of B type were divided into B1 (19 strains) and B2 (7 strains). The strains of B1 type were mainly from ICU (7 strains), neurosurgery department (4 strains) and respiratory department (3 strains). The strains of B2 type were mainly from ICU (2 strains) and respiratory department (3 strains). @*Conclusion@#The cross infection from A. baumannii may present in our hospital. There was no correlation between drug resistance and positive pattern of virulence gene in Acinetobacter baumannii.