Multiple sequence types responsible for healthcare-associated Acinetobacter baumannii dissemination in a single centre in Egypt

Abstract

Background Acinetobacter baumannii is an increasingly worrying organism in the healthcare setting, due to its multidrug resistance and persistence. Prolonged hospitalisation, immunocompromised patients and excessive antibiotic exposure all contribute to increasing the risk of A. baumannii infections, which makes cancer patients a significant risk group. This study aims to investigate the dissemination of A. baumannii at the National Cancer Institute (NCI) in Cairo – Egypt. Methods All bacterial isolates were typed using Multi-locus Sequence Typing (MLST) to characterise the epidemiology of isolates. The intrinsic OXA-51-like, and the acquired carbapanemases OXA-23, − 24/40, − 58, NDM, IMP, and VIM were also amplified and sequenced to genetically identify mechanisms of carbapenem resistance. Results MLST results show a high degree of multi-clonal dissemination, with 18 different Sequence Types (STs) identified, including 5 novel. The majority of isolates belonged to International Clone (IC) 2, and carbapenem resistance was detected in 93% of isolates and mediated by blaOXA-23, blaOXA-58, blaNDM-1 and blaVIM-1. We also report the presence of a resistant ST732 (OXA-378) which has been previously identified in migratory birds. Conclusions Multiple highly resistant clones were identified in a Cancer hospital in Cairo. It is vital that clinicians and healthcare workers are aware of the population of A. baumannii present in order to have appropriate treatment and infection control practices.

Acquisition of Colistin Resistance Links Cell Membrane Thickness Alteration with a Point Mutation in the lpxD Gene in Acinetobacter baumannii

“…In our study, 70% of the isolates were resistant to imipenem, similar to what reported in a study conducted in 2014 [26]. Unfortunately, imipenem resistance in Egypt has recently increased to around 92% of the studied cases [27,28], indicating the decrease of carbepenem effectiveness against A. baumannii infections.…”

Diversity of carbapenem-resistantAcinetobacter baumanniiand bacteriophage-mediated spread of the Oxa23 carbapenemase

“…This was reflected in our study, where oxa23 was carried by 100% of carbapenem-resistant isolates. Reports of the metallo-β-lactamases NDM-1 and NDM-2 being encoded by isolates from Egypt indicate frequencies of blaNDM-1 can typically reach up to 30% (18,71,72), though reports from specific hospitals can occasionally report higher frequencies (16,73). This is in line with our study where 6 isolates (11%) carried a blaNDM-1 gene and only 1 isolate (2%) carried a blaNDM-2 gene.…”

“…Previous studies of A. baumannii in Egypt have found that rates of carbapenem resistance are high, typically >70% (17,70), and that this is usually associated with isolates carrying the oxa23 gene with carriage frequencies reaching as high as 100% in carbapenem-resistant isolates (16)(17)(18). This was reflected in our study, where oxa23 was carried by 100% of carbapenem-resistant isolates.…”

“…The most common of these resistance mechanisms globally is oxa23 (15). In Egypt, and other countries in the region, oxa23 is so prevalent it can be found in up to 100% of carbapenem-resistant isolates, with frequencies greater than 70% being the norm (16)(17)(18)(19). In A. baumannii oxa23 is usually located on a transposon mobilised by one or more insertion sequences (IS), which has enabled the resistance gene to be spread to many different plasmids and many different lineages within the species (20).…”

“…In many low-and middle-income countries MLST is too costly to perform on large numbers of isolates, and so at present we often rely on a small number of studies to provide an indication of what the national epidemiology may be. In Egypt, studies have indicated that CC PAS 2 is the most common CC, but that a large number of isolates from other CCs or that don't belong to any of the defined CCs make up a substantial portion of the population (16,18,19,27). The aim of our study was to define the local population structure of A. baumannii in Alexandria Main University Hospital, Egypt, and identify the mobile genetic elements responsible for resistance gene dissemination.…”