Abstract
BackgroundAntimicrobial resistance in multidrug-resistant Acinetobacter baumannii (MDR-AB) isolated from burn wound infections is a major concern in intensive care or burns units worldwide, and molecular studies are considered critical strategies for control of MDR-AB outbreaks in this regard. Thus, in this study, antibiotic resistance, biofilm-forming ability, molecular epidemiology of MDR A. baumannii strains recovered from patients with burns were investigated in three major hospital centers of Iran.MethodsIn this cross-sectional research, 163 non-repetitive A. baumannii strains were tested for susceptibility to antimicrobial agents. Polymerase chain reaction (PCR) was performed to characterize ambler classes A, B, and D β-lactamases, ISAba1 and integrons, biofilm formation was also investigated. Clonal relatedness was analyzed using Pulsed-Field Gel Electrophoresis (PFGE).ResultsAmong 163 A. baumannii strains collected, 94.5% of them were Carbapenem-Non-Susceptible A. baumannii (CNSAB) and also 90.1 and 52.2% of them were Metallo-β-Lactamases (MBL) and Extended-Spectrum β-Lactamases (ESBL) producing isolates, respectively. Colistin and polymyxin B exhibited excellent activity against CNSAB strains. High prevalence of blaOXA − 23-like (85.1%), blaVIM (60.5%), blaPER − 1 (42.3%), tetB (67.8%), and Class 1 integrons (65.6%) were identified in CNSAB strains. ISAba1 element was associated with 42 (25.8%) and 129 (98.5%) of blaOXA-51-like and blaOXA-23-like genes, respectively. 6 clusters with the ability to form strong biofilms were found to be dominant and endemic in our entire areas.ConclusionsResults of the present study show that antimicrobial resistance in CNSAB isolates from burn wound infections in monitored hospitals in Iran is multifactorial, and also findings of the study suggested that local antibiotic prescription policies should be regularly reviewed, and efficient infection control measures should be observed. Therefore, further strengthening of surveillance of antimicrobial resistance is urgently needed in these regions.
Highlights
Antimicrobial resistance in multidrug-resistant Acinetobacter baumannii (MDR-AB) isolated from burn wound infections is a major concern in intensive care or burns units worldwide, and molecular studies are considered critical strategies for control of MDR-AB outbreaks in this regard
Multidrug resistance conferred by Extended-spectrum beta-lactamases (ESBL) and Metallo beta-lactamase (MBL) genes has recently been raised around the world among Carbapenem-Non-Susceptible A. baumannii (CNSAB) strains, and these resistance genes can be harbored by a transferable plasmid containing integrons or Insertion Sequence (IS) elements into chromosome becoming widely disseminated among other strains, and conferring resistance to almost all β-lactam antibiotics [3, 6]
Clinical isolates Throughout the study period, 163 A. baumannii isolates were recovered from burn wound infections in three major hospital centers located in different parts of Iran, including Valiasr Hospital (n = 52), Taleghani hospital (n = 76), and Imam Khomeini hospital (n = 35)
Summary
Antimicrobial resistance in multidrug-resistant Acinetobacter baumannii (MDR-AB) isolated from burn wound infections is a major concern in intensive care or burns units worldwide, and molecular studies are considered critical strategies for control of MDR-AB outbreaks in this regard. In this study, antibiotic resistance, biofilm-forming ability, molecular epidemiology of MDR A. baumannii strains recovered from patients with burns were investigated in three major hospital centers of Iran. Coexistence of various antibiotic resistance mechanisms including extrusion of drugs by active efflux pumps (encoded by various tet genes), Carbapenem-Hydrolyzing Class D β-Lactamases (CHDLs) (OXA-23, OXA-24/40, OXA-58, OXA-143, and OXA-235), MBLs (IMP, VIM, NDM, SPM, GIM, and SIM), ESBLs (PER, TEM, SHV,and CTX), contributes to the increase in the number of MDR- AB strains [3, 5]. Multidrug resistance conferred by ESBLs and MBLs genes has recently been raised around the world among Carbapenem-Non-Susceptible A. baumannii (CNSAB) strains, and these resistance genes can be harbored by a transferable plasmid containing integrons or Insertion Sequence (IS) elements into chromosome becoming widely disseminated among other strains, and conferring resistance to almost all β-lactam antibiotics [3, 6]. Much attention has been focused on biofilm formation in A. baumannii, because microbial cells grown in biofilms are less sensitive to antimicrobial agents and more persistent to environmental conditions such as intubation tubes, catheters, and cleaning instruments [7, 8]
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