Clonal evolution multi-drug resistant Acinetobacter baumannii by pulsed-field gel electrophoresis

Abstract

An isolate from the emergency ward of these hospitals had indistinguishable isolates PFGE profile and similar resistance profile to isolates from intensive care unit (ICU), suggesting likely transmission from ICU to emergency via patient or hospital staff contact.

Study of genetic diversity, biofilm formation, and detection of Carbapenemase, MBL, ESBL, and tetracycline resistance genes in multidrug-resistant Acinetobacter baumannii isolated from burn wound infections in Iran

“…Our study results demonstrated high prevalence rates of CNSAB, MDR-AB, and XDR-AB isolates and emergence of them in respective hospitals as a worrying tendency. In line with other studies conducted in Iran, colistin, and polymyxin B exhibited excellent activity against CNSAB strains [6, 21]. In the present study, high MIC50 and MIC90 values for carbapenems were detected and indicated a markedly reduced efficacy of these agents that could be due to their overuse.…”

“…DNA fragments were separated in 1% ultra-pure agarose gels (Invitrogen) using the CHEF Mapper apparatus (Bio-Rad, Munich, Germany) under the following conditions: voltage 6 V/cm; temperature at 14 °C; with switch times ranging from 5 s to 30s; at an angle of 120°, for 19 h. After that, the gels were stained by ethidium bromide, and the DNA bands were visualized and photographed under UV transilluminator. DNA banding pattern images were analyzed using Bionumeric 7.6.3 software (Applied Maths NV, St-Martens-Latem Belgium) and the dendrogram was constructed by UPGMA method (Unweighted Pair Group Method with Arithmetic Mean), based on Dice’s similarity coefficient at a 1.5% tolerance [6]. The similarity of 80% or higher was defined as the same PFGE genotype, whereas the similarity of < 80% indicated various PFGE genotypes.…”

“…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 also 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]. Recently, 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].…”

“…Nowadays, understanding molecular characteristics of various antibiotic resistance mechanisms along with molecular epidemiology analysis in regions with high prevalence rates of MDR A. baumannii infection plays an essential role in developing therapeutic strategies and controlling MDR-AB outbreaks, both in community and hospitals [1, 7, 10]. Among molecular typing methods, Pulsed-Field Gel Electrophoresis (PFGE) is usually considered gold standard for epidemiological typing of A. baumannii [6]. Therefore, this study was carried out to determine antimicrobial susceptibility profiles, biofilm-forming ability, resistance determinants, and clonal relatedness among MDR A. baumannii strains recovered from patients with burns in Iran.…”

The Evaluation of Four In Vitro Susceptibility Testing Methods for Colistin on Carbapenenm-Resistant Acinetobacter baumannii

“…Acinetobacter baumannii is often spread, causing outbreaks in the hospitals, throughout the cities, countries, and continents (15). Colistin is the most important available antibiotic in China, which is effective against CRAB.…”