Genomic Surveillance Uncovers a 10-Year Persistence of an OXA-24/40 Acinetobacter baumannii Clone in a Tertiary Hospital in Northern Spain

Infections caused by carbapenem-resistant Acinetobacter baumannii are a global threat causing a high number of fatal infections. This microorganism can also easily acquire antibiotic resistance determinants, making the treatment of infections a big challenge, and has the ability to persist in the hospital environment under a wide range of conditions. The objective of this work was to study the molecular epidemiology and genetic characteristics of two bla(OXA24/40)Acinetobacter baumannii outbreaks (2009 and 2020-21) at a tertiary hospital in Northern Spain. Thirty-six isolates were investigated and genotypically screened by Whole Genome Sequencing to analyse the resistome and virulome. Isolates were resistant to carbapenems, aminoglycosides and fluoroquinolones. Multi-Locus Sequence Typing analysis identified that Outbreak 1 was mainly produced by isolates belonging to ST3(Pas)/ST106(Oxf) (IC3) containing bla(OXA24/40), bla(OXA71) and bla(ADC119). Outbreak 2 isolates were exclusively ST2(Pas)/ST801(Oxf) (IC2) bla(OXA24/40), bla(OXA66) and bla(ADC30), the same genotype seen in two isolates from 2009. Virulome analysis showed that IC2 isolates contained genes for capsular polysaccharide KL32 and lipooligosacharide OCL5. A 8.9 Kb plasmid encoding the bla(OXA24/40) gene was common in all isolates. The persistance over time of a virulent IC2 clone highlights the need of active surveillance to control its spread.