Background and Objectives: Pseudomonas aeruginosa is a frequent opportunistic pathogen in health care associated infections
that is highly resistant to the majority of β-lactams. The aims of this study were to access the antimicrobial susceptibility
pattern of P. aeruginosa isolated from educational hospitals of Qazvin and Alborz provinces, to determine the prevalence of
metallo-β-lactamase (MBL) among carbapenem non-susceptible isolates by combined disk (CD) method, and to detect the
blaIMP, blaVIM, blaSIM, blaGIM, blaSPM and blaNDM-1-MBL genes.
Materials and Methods: In this cross-sectional study, 300 P. aeruginosa isolates were collected from different clinical specimens
in two provinces of Qazvin and Alborz hospitals, Iran. After identification of isolates by standard laboratory methods,
antimicrobial susceptibility was done against 17 antibiotics according to clinical and laboratory standards institute (CLSI)
guideline. CD method was carried out for detection of MBLs and the presence of blaIMP, blaVIM, blaSIM, blaGIM, blaNDM-1 and
blaSPM-genes was further assessed by PCR and sequencing methods.
Results: In this study, 107 (35.66%) isolates were non-susceptible to imipenem and/or meropenem among those 56 (52.3%)
isolates were metallo-β-lactamase producer. Twenty-four of 56 (42.85%) MBL-positive isolates were confirmed to be positive
for MBL-encoding genes in which 14 (25%) and 10 (17.85%) isolates carried blaIMP-1 and blaVIM-1 genes either alone or
in combination. Three (5.35%) isolates carried blaIMP and blaVIM genes, simultaneously.
Conclusion: Considering the moderate prevalence and clinical importance of MBL-producing isolates, rapid identification
and use of appropriate infection control (IC) measures are necessary to prevent further spread of infections by these resistant
organisms.
Keywords: Pseudomonas aeruginosa, Antibiotic resistance, Metallo-β-lactamas
