Analysis Of Resistance To Antimicrobial Agents And Homogy Of Acinetobacter Baumannii Isolated From Neurosurgery ICU

Objective:To investigate the distribution characteristic of Acinetobacter baumannii in neurosurgical intensive care unit(NICU) in a hospital of grade III level A ; To investigate the incidence of resistance for Acinetobacter baumannii to common antibiotics; To characterize the antibiotic and genetic homology of Acinetobacter baumannii isolated from NICU by pulsed-field gel electrophoresis. So to verify wheather nosocomial infection occurs in NICU, and to detern whether they were derived from the same clone, and to offer evidence for establishing the measure to prevent and control hospital onset of infection.Method:41 strains of Acinetobacter baumannii were collected from patients in NICU of a hospital of grade III level A between febrary 2007 and August 2008. The identificatian of Acinetobacter baumannii was done using Microscan WalkAway96. The antimicrobial susceptibility testing was performed with Kirby-Bauer(KB) method. The result was judged by the standard of CLSI(2007): susceptible(S), intermediate(I), and resistant(R). The clinical data which included name, gender, age, diagnosis, basic disease, time of in hospital, invasive operation, types and time of antibiotics used was analysised using SPSS13.0. The homology of 17 strains was examined by pulsed field gel electrophoresis(PFGE). The result was judged by the cirteria introducd by Tenover: a)impossible to distinguish: no different strap;b) closely related: 2-3 different straps;c) maybe related:4-6 different straps;d)no related:more than 7 different straps. The strains between which there are less than 3 different straps were considered highly homologous. They are belong to the same clone and closely related epidemiologically.Results:1. The antibiotic resistance rate of Acinetobacter baumannii to gentamycin, Cefuroxime Sodium, tobramycine, sinomin, aztreonam, amikacin, cefotaxim, and ciprofloxacin were above 50%. and that to piperacillin- sulbactam, cefoperazone- sulbactam was 41.2%and 26.8%, respectively, and that to imipenem and meropenem were both 24.4%.2. There was no relationship between the antibiotic resistance rate of Acinetobacter baumannii and gender, age and time of in hospital, however, severity of basic diseases, invasive operation such as incision of trachea, and improper use of antibiotics was connected to the antibiotic resistance rate of Acinetobacter baumannii.3. Of the 17 isolates, the spectrum of the three trains (1, 5 and 13) was identical, they are of one clone and was identified for type A. The spectrum of the two trains (3 and 4) was identical, they are of one clone and was identified for type B. The spectrum of other two trains (10 and 11) was identical, they are of one clone and was identified for type C1. There are three different straps between 10, 11 and 14, they are highly similar and maybe of one clone and was identified for type C2. There are more than 4 different straps in other isolates: and they were identified for type D, E, F, G respectively. Conclusion:Acinetobacter baumannii is one of the important pathogenic bacteria of nosocomial infection in neurosurgical intensive care unit; The risk factors that facilitate infection of Acinetobacter baumannii included severity of basic diseases, invasive operation such as incision of trachea, and improper use of antibiotics; There is serious bacterial resistance of Acinetobacter baumannii in NICU. Multiple antibiotic resistant strains and pan-drug resistant strains can be detected; Pulsed-field gel electrophoresis reveals that there are small scale infection with same clone of Acinetobacter baumannii in NICU.