Extensively drug-resistant Acinetobacter baumannii: role of conjugative plasmids in transferring resistance.

Acinetobacter baumannii is one of the most successful pathogens that can cause difficult-to-treat nosocomial infections. Outbreaks and infections caused by multi-drug resistant A. baumannii are prevalent worldwide, with only a few antibiotics are currently available for treatments. Plasmids represent an ideal vehicle for acquiring and transferring resistance genes in A. baumannii. Five extensively drug-resistant A. baumannii clinical isolates from three major Jordanian hospitals were fully sequenced. Whole-Genome Sequences (WGS) were used to study the antimicrobial resistance and virulence genes, sequence types, and phylogenetic relationship of the isolates. Plasmids were characterized In-silico, followed by conjugation, and plasmid curing experiments. Eight plasmids were recovered; resistance plasmids carrying either aminoglycosides or sulfonamide genes were detected. Chromosomal resistance genes included blaOXA-66, blaOXA-91, and blaOXA-23, and the detected virulence factors were involved in biofilm formation, adhesion, and many other mechanisms. Conjugation and plasmid curing experiments resulted in the transfer or loss of several resistance phenotypes. Plasmid profiling along with phylogenetic analyses revealed high similarities between two A. baumannii isolates recovered from two different intensive care units (ICU). The high similarities between the isolates of the study, especially the two ICU isolates, suggest that there is a common A. baumannii strain prevailing in different ICU wards in Jordanian hospitals. Three resistance genes were plasmid-borne, and the transfer of the resistance phenotype emphasizes the role and importance of conjugative plasmids in spreading resistance among A. baumannii clinical strains.

The oxygen dilemma: The challenge of the anode reaction for microbial electrosynthesis from CO2.

Microbial electrosynthesis (MES) from CO2 provides chemicals and fuels by driving the metabolism of microorganisms with electrons from cathodes in bioelectrochemical systems. These microorganisms are usually strictly anaerobic. At the same time, the anode reaction of bioelectrochemical systems is almost exclusively water splitting through the oxygen evolution reaction (OER). This creates a dilemma for MES development and engineering. Oxygen penetration to the cathode has to be excluded to avoid toxicity and efficiency losses while assuring low resistance. We show that this dilemma derives a strong need to identify novel reactor designs when using the OER as an anode reaction or to fully replace OER with alternative oxidation reactions.

Molecular epidemiology of carbapenem-resistant Acinetobacter baumannii isolated from three major hospitals in Jordan.

BACKGROUND: In the last decade, incidences of carbapenem-resistant Acinetobacter baumannii have been increasingly reported worldwide. Consequently, A. baumannii was included in the World Health Organization's new list of critical pathogens, for which new drugs are desperately needed. The objective of this research was to study the molecular epidemiology and antimicrobial susceptibility of clinical carbapenem-resistant A. baumannii isolated from Jordanian hospitals. METHODS: A total of 78 A. baumannii and 8 Acinetobacter spp. isolates were collected from three major hospitals in Jordan during 2018. Disc diffusion and microdilution methods were used to test their susceptibility against 19 antimicrobial agents. Multilocus sequence typing (MLST) was performed using the Pasteur scheme, followed by eBURST analysis for all isolates. PCR was used to detect ß-lactam resistance genes, blaOXA-23-like , blaOXA-51-like , and blaNDM-1 . RESULTS: Of the 86 tested isolates, 78 (90.6%) exhibited resistance to carbapenems, whereas no resistance was recorded to tigecycline or polymyxins. Based on the resistance profiles, 10.4% and 84.8% of isolates were classified into multidrug resistant (MDR) or extensively drug resistant (XDR), respectively. The most prevalent carbapenems resistance genes amongst isolates were blaOXA-51-Like (89.5%), followed by blaOXA-23-Like (88.3%) and blaNDM-1 (10.4%). MLST revealed the presence of 19 sequence types (STs), belonging to eight different international complexes. The most commonly detected clonal complex (CC) was CC2, representing 64% of all typed isolates. CONCLUSIONS: This is the first study to report the clonal diversity of A. baumannii isolates in Jordan. A high incidence of carbapenem resistance was detected in the isolates investigated. In addition, our findings provided evidence for the widespread of blaOXA-23-like harbouring carbapenem-resistant A. baumannii and belonging to CC2. The number of XDR isolates identified in this study is alarming. Thus, periodic surveillance and molecular epidemiological studies of resistance factors are important to improve treatment outcomes and prevent the spread of A. baumannii infections.