Class 1 integrons in environmental and clinical isolates of Pseudomonas aeruginosa

Abstract

The aims of this study were to ascertain the presence and spread of class 1 integrons among environmental and clinical isolates of Pseudomonas aeruginosa and to characterise their variable regions. A total of 76 isolates (56 clinical and 20 environmental) were studied. The presence of plasmids was explored, and polymerase chain reaction (PCR) was used for integron detection. All amplicons were sequenced. PCR detected class 1 integrons in 26 of the 56 clinical isolates; environmental isolates were integron-free. No plasmids were found, thus all the integrons found are possibly on the chromosome. Most isolates presented one amplicon, except PA110514 and PA116136, which showed two PCR products each.Variable regions revealed that 18 strains carried only one gene involved in aminoglycoside resistance, whereas in 3 strains gene cassettes were not found. The most prevalent cassettes among isolates were those encoding aminoglycoside adenyltransferase B (aadB). Several of the strains had acquired the same or a highly similar cassette array as those detected in geographically distant P. aeruginosa. This finding suggests that contact with bacterial reservoirs contributes to the evolution of this pathogen towards multiresistance. Empty structures found may represent a reservoir increasing the capacity to adapt to the environment. However, these integrons are not retained when the selective pressure disappears. It is hypothesised that integrons containing gene cassettes are crucial vehicles for the rapid horizontal transfer of resistance. If this is so, reduced use of antibiotics may lead to a significant decrease in the carriage of integrons among P. aeruginosa strains.

Prevalence of Antibiotic Resistance and Class 1 Integrons in Clinical and Environmental Isolates ofPseudomonas aeruginosa

“…The results of the current study were consistent with those of the study by Ruiz et al in Spain (30). In that study, 26 out of 56 clinical isolated P. aeruginosa strains contained class 1 integron that had the highest prevalence in the aadB gene cassette.…”

Class 1 Integron in Pseudomonas aeruginosa Isolates From Different Places and Devices of ICU in Babol, Iran

“…The present study investigating the existence of integron revealed that 39.4% of the isolates contained integron classes 1. This is comparable with previously reported frequencies of 40.8% in China, 41.5% in Brazil (P. aeruginosa), 60% in the United Kingdom (Acinetobacter baumannii), 43% in Europe (Gram-negative isolates), 50% in The Netherlands (Enterobacteriaceae), 59% in France (Enterobacteriaceae), and 52% in Taiwan (Escherichia coli) (16,17). The reported percentages were higher compared to our study, which can be all due to the differences among geographical regions and the bacteria strains.…”

Comparison of Local Features from Two Spanish Hospitals Reveals Common and Specific Traits at Multiple Levels of the Molecular Epidemiology of Metallo-β-Lactamase-Producing Pseudomonas spp

“…Furthermore, the Southern blot hybridization following described protocols (15) using the North2South complete biotin random primer labeling and detection kit (Thermo Scientific), over the I-CeuI/S1 nuclease-digested genomes, suggested the chromosomal location of MBL genes in all the strains, given that the respective MBL gene probes hybridized with bands which also hybridized with the rRNA gene probe (data not shown). This finding is supported by several previous studies that have also shown that the majority of MBL genes are chromosomally located in P. aeruginosa, probably due to a poor replication of plasmids within this species, and the necessity of a chromosome integration of the genes (24,25). Moreover, chromosomal location was also observed in all P. putida strains analyzed.…”