Antimicrobial resistance pattern and molecular genetic distribution of metallo-β-lactamases producing Pseudomonas aeruginosa isolated from hospitals in Minia, Egypt

Background: Pseudomonas aeruginosa (P. aeruginosa) represents a great threat to public health worldwide, due to its high ability to acquire resistance to different antibiotic classes. Carbapenems are effective against multidrug resistant (MDR) P. aeruginosa, but their widespread use has resulted in the emergence of carbapenem-resistant strains, which is considered a major global concern. This study aimed to determine the prevalence of carbapenem resistance among P. aeruginosa strains isolated from different sites of infection. Methods: Between October 2016 and February 2018, a total of 530 clinical specimens were collected from patients suffering from different infections, then processed and cultured. Isolates were tested for extended spectrum β-lactamase (ESBL) and metallo-β-lactamase (MBL) production using double-disk synergy test, modified Hodge tests, and disc potentiation test. PCR was used for the detection of selected OXA carbapenemases encoding genes. Results: Of 530 samples, 150 (28.3%) P. aeruginosa isolates were obtained. MDR strains were found in 66.6% (100 of 150) of isolates. Of 100 MDR P. aeruginosa isolates, 54 (54%) were ESBL producers and 21 (21%) carbapenem resistant P. aeruginosa. MBL production was found in 52.3% (eleven) carbapenem-resistant isolates. CTX-M15 was found among 55.5% of ESBL- producing P. aeruginosa. Carbapenemase genes detected were bla(IMP) (42.8%, nine of 21), bla(VIM) (52.3%, eleven of 21), bla(GIM) (52.3%, eleven of 21), bla(SPM) (38%, 8/21). In addition, isolates that were positive for the tested genes showed high resistance to other antimicrobials, such as colistin sulfate and tigecycline. Conclusion: Our study indicates that P. aeruginosa harboring ESBL and MBL with limited sensitivity to antibiotics are common among the isolated strains, which indicates the great problem facing the treatment of serious infectious diseases. As such, there is a need to study the resistance patterns of isolates and carry out screening for the presence of ESBL and MBL enzymes, in order to choose the proper antibiotic.