Nosocomial Infection Of Carbapenem-resistant Acinetobacter Baumannii At Multiple Medical Centers In Anhui Province

Objective To explore the epidemiological charateristics of the antibiotic resistance of Acinetobacter baumannii at multiple medical centers in Anhui Province so that it might be helpful to provide a guideline for clinical reasonable usage of antibiotics.This study also aims to examine the epidemiologic features of CRAB so that nosocomial infections can be reduced and to further provide useful information for the establishment of standard clinical performance.Materials and Methods Isolates A total of 540 strains of non-repeat Acinetobacter baumannii isolated from the specimens from patients(sputum,urine,secretion and blood)in 38 tier 3 level hospitals in Anhui Province in September,2015 and in September,2016.For quality control,two widelyused bacterial strains Escherichia coli ATCC25922 as well as Pseudomonas aeruginosa ATCC27853 were also included in the test of antimicrobial susceptibility.These control strains used in this study were safely saved in Anhui Center of Surveillance of Bacterial Resistance.Methods 1.460 strains out of the 540 non-repeat Acinetobacter baumannii isolated from thespecimens from patients in 38 tier 3 level hospitals in Anhui Province in September,2015 and in September,2016 mentioned above were further confirmed by the First Affiliated Hospital of Anhui Medical University by using VITEK-2 Compact totallyautomatic Microbe Identifier and the AP120 Kit.2.Agar plate dilution method was used to determine the MIC of 16 antibiotics to these 460 strains of non-repeat Acinetobacter baumannii according to Clinical and Laboratory Standards Institute guideline(CLSI,2016).3.312 strains of Carbapenem-resistant A.baumannii(CRAB)were selected and analyzed based on the MIC to 16 antibiotics by using agar plate dilution method.4.Only 145 strains out of these 312 strains of CRAB isolated from the specimens from patients in the same or different Department within the same hospitals from these 38 tier 3 level hospitals in Anhui Province(11 hospitals in total)in September,2015 and in September,2016 mentioned above were further investigated.For these 145 strains,PCR and clonal sequencing was used to determine the corresponding gene types.5.In these 145 strains,specifically,the carbapenemase genes(bla OXA-23-like gene,bla OXA-24-like gene,bla OXA-51-like gene,bla OXA-58-like gene,bla VIM,bla NDM,bla IMP and bla KPC gene)were analyzed by PCR and clonal sequencing.PFGE was used to analyze the homology of these 145 strains.Results 1.Our results revealed that all of the 460 strains of non-repeat Acinetobacter baumannii isolates showed resistance to these 16(14)antibiotics tested to some extent.Regarding the resistance to the 16 antibiotics,only 0.43% of the isolates showed resistance to POL B and 32.2% of the isolates showed resistance to MNO.Over 54% of the isolates showed drug resistance to the other drugs and over 70% of the isolates showed drug resistance to cephalosporins?The drug resistance rates of these isolatesto Imipenem and Meropenem were 67.9% and 70.6% respectively.2.312 out of 460 isolates were CRAB and showed resistance multiple drugs including cephalosporins,penicillins,aminoglycosides,fluorquinolones,Sulfonamides and tetracyclins 3.Genotype analysis was also performed for the 145 strains of CRAB.bla OXA-51 was detected in 100%(145/145)of strains,bla OXA-23 was detected in 92.41%(134/145)of strains,bla OXA-24 was detected in 1 strain(1/145),and the subtype of bla IMP-4 was detected in 4 strains(4/145).No other drug resistance genotypes were detected.By PFGE analysis,80 different types(PT1-PT80)were identified in these 145 isolates.60 types were identified in single strain and the other 20 types were identified in two or more strains.Conclusions 1.A.baumannii has become one of the most critical microbes which are responsible for the nosocomial infections in Anhui province,China.A.baumannii isolated from hospital in Anhui Province showed a higher resistance to 14 widely used drugs in clinics tested except POL B or MNO.Over 54% of isolates have been shown to be resistant to drugs which are higher than that of national average which are 50% of isolates.Thus,Anhui Province is one of the most infected provinces by A.baumannii.2.CRAB in Anhui Providence has demonstrated multiple types of drug resistance and its rate for drug resistance is higher that data previously reported in CHINET.The higher incidence of the infection by A.baumannii together with the incurrence of XDRAB is a great challenge for the efficacy of antibiotic treatment to patients.3.In these 145 clinical CRAB strains,bla OXA-51 was detected in 100%(145/145)of strains,bla OXA-51 was the inherent drug resistant associated gene in the chromosome of AB.Bla OXA-23 was the Carbapenemase in bacterium which wasthe most common cause of nosocomial infection in Anhui Province.Homologous analysis indicated that all of these 145 CRAB strains might play a role in the interhospital,intrahospital,interdepartmental and intradepartmental infection of CRAB.Clearly,nosocomial CRAB infection is widespread in Anhui Province.