Three Novel Class 1 Integrons Detected in Multidrug-Resistant Pseudomonas aeruginosa Hospital Strains

The antibacterial resistance of healthcare-associated infection (HAI) agents is a major public health problem worldwide. Pseudomonas aeruginosa is one of the main HAI agents, especially in intensive care units (ICUs). The present study focuses on the identification of antibacterial resistance genetic determinants and on determining the structure of mobile genetic elements—novel class 1 integrons of P. aeruginosa. P. aeruginosa strains (n = 105) were collected in the Department of the Moscow Neurosurgery ICU in 2013–2016 from the respiratory system (60.0%), urine (28.6%), surgical wounds (5.7%), blood (2.9%), and cerebrospinal fluid (2.9%). The majority (92.4%) of strains were characterized by a phenotype of multidrug-resistance. Beta-lactamase genes bla_VIM-2-like, which are widely distributed in Russia, were identified in 37.7% of strains. The bla_CTX-M-15 gene was carried by 3.0% of strains that is the first report of such gene identification in P. aeruginosa in Russia. Class 1 integrons were detected in 63.0% of strains, with 36.7% of strains carrying seven types of gene cassette arrays: (bla_VIM-2-like), (aadA6-gcuD), (aacA7-bla_VIM-2-like), (aac(3 ')Ic-cmlA5), (aadA6Δ3::ISPa21e-gcuD), (gcu87-aadB-aphA15d-aadA1a), and (bla_PBL-1-aacA4). The latter three gene cassette arrays are new for class 1 integrons. Identification numbers have been assigned to novel integrons: In1379, In1360, and In1375. New genetic structures were described: the aadA6 gene cassette with inserted ISPa21уe element (In1379); the gsu87 gene cassette coding hypothetical protein which is not represented in the GenBank database (In1360); novel allele of aphA15d gene cassette and the bla_PBL-1 gene cassette coding new, not previously described, beta-lactamase of class A (In1375). Identification of novel genetic structures of antibacterial resistance in P. aeruginosa strains isolated in the course of 3 years indicates the activity of genetic processes associated with antibiotic resistance in hospital pathogens in the Department of Neuro-ICU, which indicates the activity of genetic processes associated with the formation of multiple drug resistance of hospital pathogens.