Abstract
Understanding the biology behind the epidemicity and persistence of Acinetobacter baumannii in the hospital environment is critical to control outbreaks of infection. This study investigated the contributing factors to the epidemicity of carbapenem-resistant A. baumannii (CRAB) sequence type (ST) 191 by comparing the differences in biofilm formation, expression of biofilm-associated genes, and resistance to desiccation between major epidemic (n = 16), minor epidemic (n = 12), and sporadic (n = 12) clones. Biofilm mass was significantly greater in the major epidemic than the minor epidemic and sporadic clones. Major and minor epidemic clones expressed biofilm-associated genes, abaI, bap, pgaABCD, and csuA/BABCDE, higher than the sporadic clones in sessile conditions. The csuC, csuD, and csuE genes were more highly expressed in the major epidemic than minor epidemic clones. Interestingly, minor epidemic clones expressed more biofilm-associated genes than the major epidemic clone under planktonic conditions. Major epidemic clones were more resistant to desiccation than minor epidemic and sporadic clones on day 21. In conclusion, the epidemic CRAB ST191 clones exhibit a higher capacity to form biofilms, express the biofilm-associated genes under sessile conditions, and resist desiccation than sporadic clones. These phenotypic and genotypic characteristics of CRAB ST191 may account for the epidemicity of specific CRAB ST191 clones in the hospital.
Highlights
Acinetobacter baumannii is a Gram-negative lactose non-fermenting pathogen capable of causing nosocomial infections among severely ill patients [1,2]
We previously demonstrated that carbapenem-resistant A. baumannii (CRAB) sequence type (ST) 191 emerged as an epidemic clone and circulated in our hospital between 2011 and 2012 [17]
Epidemic and sporadic CRAB ST191 clones were defined based on the pulsotypes generated by pulsedfield gel electrophoresis (PFGE) of CRAB isolates in the previous study [17]
Summary
Acinetobacter baumannii is a Gram-negative lactose non-fermenting pathogen capable of causing nosocomial infections among severely ill patients [1,2]. Once considered intrinsically tolerant to many antimicrobial agents, A. baumannii has become increasingly resistant to clinically. Contributing Factors to the Epidemicity of CRAB ST191 useful antibiotics through the capacity to acquire antimicrobial resistance determinants. Multi-drug resistant clones have emerged and circulated globally [3,4,5]. Resistance to myriad numbers of antimicrobial agents coupled with the ability of A. baumannii to persist and spread in healthcare settings has emerged as a global issue. Understanding the factors associated with the persistence and epidemicity of this opportunistic pathogen in healthcare environments may aid in the control of outbreaks in hospitals
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