The relationship between acquired carbapenemases and resistance of gram-negative bacill / 中华检验医学杂志

ABSTRACT

Objective To investigate acquired carbapenemases and prevalence of carbapenem- resistant gram-negative bacill.Methods The antimicrobial susceptibility was determined by agar dilution method.Metallo-B-lactamase(MBLs)were screened by EDTA-disk synergy tesL The encoding genes of MBLs were amplified by PCR followed by sequencing.Strain homology Was investigated by pulsed-field gel electronphoresis(PFGE).Results In 141 carbapenem-resistant Pseudomonas aeruginosa(P.aeruginosa), there were three resistant patterns which were imipenem(IMP)-resistant+meropenem(MEM)-resistant (66.7%),IMP-resistant+MEM-sensitive(32.6%),and IMP-resistant+MEM-sensitive(0.7%).AⅡthe carbapenem-resistan Acinetobacter baumannii(A.baumannii),Acinetobacter lwoffi(A.lwoffi),Citrobactor freundii(C.freundii),Klebsielta pneumoniac(K.pneumoniac)and Serratia were resistant to imipenem and meropenem.Four strains of 141 P.aeruginosa were positive by EDTA-disk synergy test,and they produced VIM-2-type Metallo-B-1actamase.Of 34 carbapenem-resistan A.baumannii,30 strains produced OXA-tllrpe.Among them, OXA23, OXA24 and OXA66 accounted for 79.4%,38.2% and 67.6%,respectively.And 22 of 34 strains(64.7%)produced multiple OXA-carbapenemases.All 7 strains A.lwoffi produced OXA-23-type carbapenemases.A11 11 strains C.freundii,5 strains k pneumoniac and 1 strains Serratia produced KPC-2-type carbapencmases.And 6 of 11 strains C.freundii produced new subtype IMP-8.Of 15 PFGE type in 34 strains A.baumannii,14 strains belonged to A-type,7 strains belonged to B-type.Seven A.lwoffi strains distilbuted in difierent PFGE type.Four strains of P.aeruginosa producing VIM-2.type Metallo-8-lactamase did not have the same PFGE type.Eleven C.freundii strains had the same PFGE type.Five k pneumoniae strains had the sanle PFGE type.Conclusions Drug resistance to 12 common antibiotics in carbapenem-resistant gram-negative bacill was higher than non-carbapenem-resistant gram-negative.The former produced many kinds of carbaponemases and the strains prducing carbapenemases were prevalent in the C.freundii, A.baumanii, and k pneumoniae.