Detection of ESBLs,AmpC β-Lactamase and AmpC genotype in Enterobacter cloacae and analysis of their drug resistance

Objective To investigate the production of ESBLs and AmpC β-Lactamase in Enterobacter cloacae,and identify AmpC β-lactamase-producing strains and their resistance to common antibiotics,providing the basis for drug options in clinical treatment.Methods Microbiological identification was performed with the VITEK 60 System.The confirmatory test recommended by CLSI was carried out to detect ESBLs,and the Kirby-Bauer method was used to determine drug sensitivity.AmpC β-lactamase-producing suspects were screened by cefoxitin disk diffusion,and their genotypes were analyzed using the cefoxitin three-dimensional test,conjugation test and PCR sequencing.Results Of 157 isolates,31.32% were ESBLs-producing and 32.48% were AmpC β-lactamase-producing strains.The proportion of simple AmpC β-lactamase-producing,AmpC β-lactamase-producing plus ESBLs-producing,and simple ESBLs-producing strains amounted to 17.20%,7.64% and 23.57%,respectively.As for the drug-resistant genotypes of AmpC β-lactamase-producing strains,30 were of DHA type and 9 of CIT type.The resistance of β-lactamase-producing isolates was obviously higher than non-β-lactamase-producing ones;and this difference was more noticeable when comparing to AmpC β-lactamase-and ESBLs-producing ones.However,the sensitivity to imipenem was almost 100% in both groups regardless of the capability of producing β-lactamase and/or ESBLs.Conclusion ESBLs-and AmpC-β-lactamase-producing Enterobacter cloacae are prevalent in Taizhou.DHA-1 genotype strains are the predominant AmpC-β-lactamase-producing bacteria.It is important to restrict the application of β-lactam antibiotics to control the occurrence of these highly drug-resistant AmpC and ESBLs-producing germs.