Study On Molecular Epidemiology And The Antiseptic Resistance Gene Of Acinetobacter Baumannii

Acinetobacter baumannii is Gram-negative non-fermenting coccobacilli.Its ability to resistant to desiccation and produce biofilm allows it to survivelong-term in healthcare environment. Acinetobacter baumannii often involveenvironmental contamination of items such as resuscitation equipment,ventilators, suctioning equipment, infusion pumps, shower trolleys,washbasins, bedrails, bedside tables, sinks, pillows and mattresses, bandagesand steel carts. Host contributions to pathogenicity include a history ofhematonosis, chronic nephritis, diabetes and cancer, invasive procedures suchas surgery, mechanical ventilation, catheters and underlyingimmunocompromised conditions. It causes various infections, such asventilator-associated pneumonia, bloodstream infection, urinary tract infection,wound infection, endocarditis, osteomyelitis, and infection associated withperitoneal dialysis. In addition Acinetobacter baumannii has become resistantto almost all commonly used multiple antimicrobial agents, includingβ-lactams, aminoglycosides, quinolones and appears pan-drug resistant totigecycline and/or polymyxin. It has been a serious nosocomial pathogen. So itshould be taken effective disinfection and isolation measures to prevent theirinhabitation and transmission in healthcare settings.Biocides (preservatives, disinfectants, and sterilants) play an essentialrole in infection control and the prevention of nosocomial transmission ofinfectious microorganisms. However, as with more-frequent use ofdisinfectants, its actual concentration is unknown. Bacteria may adapt to thesub-lethal concentrations of disinfectants, it contributes to the emergenceand/or selection of pathogens that are less susceptible to disinfectants. Severalgenes associated with disinfectants were detected, such as qacEΔ1-sul1gene.It seems to be widely disseminated in gram-negative bacteria，qacEΔ1-sul1 gene is located on class1integron and associated with QACs (such asbenzalkonium chloride, benzalkonium bromide and cetylpyridinium chloride)and biguanides (such as chlorhexidine and alexidine). Several studies havereported the carrying rate of qacEΔ1-sul1gene was high in Acinetobacterbaumannii. Carrying qacEΔ1-sul1gene may be reduced susceptibility orresistance to QACs and biguanides in Acinetobacter baumannii. Infectioncontrol department and healthcare staff should pay attention to Acinetobacterbaumannii. Disinfectants based on QACs and biguanides and symclosene areextensively used in hospitals, it is worth checking the susceptibility todisinfections of Acinetobacter baumannii to adjust the concentration ofdisinfections and infection control.Objective:The purpose of this study was to investigate the clinical distribution,antibiotic susceptibility of clinical isolated Acinetobacter baumannii. Allisolates were examined for the homology to provide a better understanding ofAcinetobacter baumannii epidemiology within the hospital and the possibletransmission routes. Monitoring the sensitivity of disinfectants and thepresence of the antiseptic resistance gene can contribute to select and usedisinfectants, in order to prevent transmission in hospitals.Methods:73isolates of non-repetitive multidrug resistant Acinetobacter baumanniiwere collected from The Third Hospital of He Bei Medical University fromOctober2012to June2013, isolates were identified by ID32E. Thesusceptibility to different antibiotics was assessed with Kirby-Bauer diskdiffusion method. Epidemiological typing was performed by enterobacterialrepetitive intergenic consensus-polymerase chain reaction (ERIC-PCR).Polymerase chain reaction (PCR) was used to detect the antiseptic resistancegene (qacEΔ1-sul1). Broth dilution method was used to determine theminimum inhibitory concentrations of symclosene.Results:73isolates of multidrug resistant Acinetobacter baumannii are resistant to multiple clinical antimicrobial agents. The resistance level to Piperacillin97.26%, Ceftazidime95.89%, Imipenem94.52%, Cefoperazone97.26%,Ceftriaxone95.89%, Gentamicin94.52%, Ciprofloxacin95.89%, Amikacin94.52%, Piperacillin-Tazobactam95.89%, Cefepime95.89%, Cefoperazone-Sulbactam43.84%, Levofloxacin86.30%, Trimethoprim-Sulfamethoxazole95.89%. Genotypic analysis of these isolates revealed8distinct patterns, A(n=31), B (n=15), C (n=12), D (n=8), E (n=3), F (n=2), G (n=1), H(n=1).Pattern A and B were the dominating clone, distributed in differentwards. ICU had6distinct patterns, A (10), B (7), C (5), D (5), F (1), G (1)respectively. Department of orthopedics had4distinct patterns, A (10), B (4),C (5), D (1). Emergency department had5distinct patterns, A (3), B (1), C (1),D (1), E (1), respectively. Internal medicine had6distinct patterns, A (5), B(3), C (1), E (1), F (1), H (1), respectively. Surgical department had3distinctpatterns, A (3), D (1), E (1), respectively. The qacEΔ1-sul1gene was detectedin50.68%of the isolates. ICU had12isolates; Department of orthopedics had7isolates; emergency department had5isolates; Internal medicine had3isolates, surgical department had3isolates. The MIC of symclosene for7isolates was250mg/L, the MIC of symclosene for28isolates was300mg/L,the MIC of symclosene for25isolates was400mg/L, and the MIC ofsymclosene for13isolates was500mg/L.Conclusion:The resistance level of Acinetobacter baumannii is high. Multiplegenotypes of Acinetobacter baumannii spread in hospital. The carrying rate ofantiseptic resistance gene is high, but the concentration of chlorine-containingdisinfectant in practice can kill Acinetobacter baumannii. So it should strengththe management of disinfection. Timely monitoring antiseptic resistance geneand susceptibility to disinfectants of main clinical target bacteria contributes tohospital infection control.