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Objective: Multidrug-resistant bacteria, including carbapenem-resistant Acinetobacter baumannii (CRAB), are considered a major public health threat, particularly those which are responsible for nosocomial infections. This study aimed to investigate the molecular mechanism of carbapenem resistance and the clonal relationship of CRAB isolates of a probable outbreak in the intensive care unit (ICU) of Saydet Zgharta University Medical Center, in north Lebanon. Methods: Thirty-two non-duplicate CRAB isolates were collected from patients hospitalised in the ICU. Antibiotic susceptibility testing was carried out using the disk diffusion method and carbapenemase-encoding genes were searched for using standard polymerase chain reaction. Epidemiological relatedness was studied using multilocus sequence typing. Results: Polymerase chain reaction and multilocus sequence typing results suggested the presence of two different periods: period 1 (November 2018 to February 2019), where 15 CRAB isolates were collected harbouring the blaOXA-23 and blaOXA-24 genes mainly and belonging to several clones; and period 2 (March to May 2019), considered an outbreak period where 17 carbapenem-resistant isolates were isolated, harbouring mostly the blaNDM-2 gene, never previously described in Lebanon and belonging to ST103. Infection control measures implemented in Saydet Zgharta University Medical Center successfully eradicated the NDM-2-producing CRAB ST103 clone, thus putting an end to this outbreak in the ICU department. Conclusions: This study showed that infection control measures and adequate identification of NDM-producing A. baumannii remain a powerful tool to limit the spread of such resistant micro-organisms.

Cassava is an important root crop that is produced by smallholder farmers across Sub-Saharan Africa. Cassava mosaic disease (CMD), which is caused by a group of cassava mosaic begomoviruses (CMBs), is one of the most devastating diseases of cassava. A previous study showed that SEGS-1 (sequences enhancing geminivirus symptoms), which occur both in the cassava genome and as episomes during CMD, can increase CMD disease severity and overcome host resistance. In this report, we examined the effects of exogenously applied SEGS-1 on the incidence of CMB infection, symptom severity, and viral DNA copy number in five cassava cultivars that ranged from highly susceptible to highly resistant to CMD. These studies revealed that the effect of SEGS-1 is cultivar dependent. Susceptible cultivars developed severe CMD with or without exogenous SEGS-1, while exogenous SEGS-1 increased disease severity in cultivars carrying CMD2 resistance, which is conferred by a single locus, but not CMD1 resistance, which is polygenic. Analysis of infected plants in the absence of exogenous SEGS-1 revealed that some, but not all, cultivars form SEGS-1 episomes during CMD. The presence of endogenous SEGS-1 episomes in TME14, a CMD2 resistant cultivar, correlated with CMD severity. In contrast, TME3, a closely related CMD2 cultivar, did not produce endogenous SEGS-1 episomes and was more resistance than TME14. The different capacities of TME3 and TME14 to form SEGS-1 episomes is unlikely due to sequence differences in and around their genomic SEGS-1 loci. The functional regions of SEGS-1 were mapped using TME3 to sequences flanking the episome junction, but the junction itself was not required for activity. All cassava cultivars have SEGS-1 sequences in their genomes that have the potential to negatively impact the development of stable CMD resistance by cassava breeding programs.