Epidemiology and virulence of VIM-4 metallo-beta-lactamase-producing Pseudomonas aeruginosa isolated from burn patients in eastern Algeria

• A high rate of P. aeruginosa infections (62%) among burn patients was observed.
• The rate of carbapenem-resistant P. aeruginosa (CRPA) was 48.3%.
• We describe the first report of VIM-4-producing P. aeruginosa in North Africa.
• Risk factors for CRPA infection were urinary catheter use and intubation.
• A high percentage of virulence factors and antimicrobial resistance were observed.

In this study, we investigated the prevalence of carbapenem-resistant Pseudomonas aeruginosa (CRPA) in burn patients from eastern Algeria, CRPA virulence factors and the molecular epidemiology of CRPA. The overall prevalence of CRPA was 48.38%. Seven (46.66%) isolates were metallo-β-lactamases (MBL) producers and contained the MBL genes blaVIM-4 (n = 6) and blaVIM-2 (n = 1). Risk factors for CRPA infection were urinary catheter use and intubation (p = 0.008). A high percentage of virulence factors (86.6% of these isolates were able to produce protease; 73.3% of isolates has DNase; and 66.6% were haemolysin positive) was observed in CRPA isolates. Among the seven MBL-producing isolates, four had the same clonal profile. The class 1 integrons, which contained the aadA7 gene cassette, were detected in six isolates. The 16SrRNA methylase gene, rmtB, was detected in one strain. All CRPA isolates were biofilm formers. A study on the kinetics of biofilm production revealed that biofilm production increased when the concentration of imipenem or ciprofloxacin and the incubation time increased. This is the first study to report the presence of VIM-4-producing P. aeruginosa from North Africa and also of the high prevalence of CRPA isolates. Based on our study of burn unit patients, the high percentage of P. aeruginosa with virulence factors and multi-drug resistance is alarming.