Clonal Spread Of Per-1 And Oxa-23 Producing Extensively Drug Resistant Acinetobacter Baumannii During An Outbreak In A Burn Intensive Care Unit In Tunisia

Extensively drug resistant Acinetobacter baumannii (XDR-Ab), has emerged as an important pathogen in several outbreaks. The aim of our study was to investigate the eventual genetic relatedness of XDR-Ab strains recovered from burn patients and environment sites in the largest Tunisian Burn Intensive Care Unit (BICU) and to characterize beta-lactamase encoding genes in these strains. Between March 04th, 2019 and April 22nd, 2019 an outbreak of XDR-Ab was suspected. Environmental screening was done. All isolates were screened by simplex PCR for beta-lactamase genes. Genetic relatedness was determined by pulsed field gel electrophoresis (PFGE) of ApaI-digested total DNA. During the study period, 21 strains of A. baumannii were isolated in burn patients, mainly in blood culture (n - 7) and central vascular catheter (n - 6). All strains were susceptible to colistin but resistant to imipenem (n = 23), ciprofloxacin (n - 23), amikacin (n - 22), tigecyclin (n - 5) and rifampicin (n - 4). The bla(OXA-51) like, bla(OXA23), and bla(ADC) genes were present in all strains. These resistance determinants were associated with bla(FER-1) in 10 strains. The ISAbaI was inserted upstream of bla(OXA-23) in all isolates. PFGE revealed two major clusters A (n = 11) and B (n = 5). This is the first description in Tunisia of clonally related PER-1 producing XDR-Ab in burn patients with probable environmental origin.