Novel Class 1 Integrons in Multi-drug Resistant Isolates from Eastern China

Abstract

Integrons are mobile genetic elements able to capture, express and excise resistance genes, playing an important role in the spread of bacterial resistance. The present study was to investigate the occurrence and diversity of integrons in 120 clinical multi-drug resistant Gram-negative isolates from eastern China. Screening of integrons was performed by PCR and gene cassettes were further characterized by PCR-RFLP and sequencing. Class 1 integrons were detected in 70.8 % of isolates and no class 2 and class 3 integrons were detected in any isolates. A total of 19 resistant gene cassettes were identified, four representative of novel gene cassettes: an aacA3 variant (aacA3c), an aacA4 variant (aacA4 0 -17), a bla OXA variant (bla OXA-251 ), and a catB8 gene cassette interrupted by an insertion sequence IS10 (catB8::IS10). In addition, 14 cassette arrays were detected, including three novel integrons:gcuD1-aacA4 0 -17-gcu38B-catB8::IS10 (In712), aacA3c-aadA13-bla OXA-251 (In713) and dfrA1-gcu37-aadA5 (In714). The presence of novel integron structures in clinical isolates suggests hospital environments may favor the formation of novel combination of gene cassettes. Moreover, the high prevalence of integrons in multi-drug resistant isolates highlights the urgent need to employ effective means to avoid dissemination of drug-resistant bacteria.

The frequency of class1 and 2 integrons in Pseudomonas aeruginosa strains isolated from burn patients in a burn center of Ahvaz, Iran

“…While the prevalence of int2 gene is documented in some reports [ 24 , 27 ], none of P . aeruginosa strains in this study were found to carry int2 gene, which was in concordant to other previous reports [ 6 , 25 ].…”

“…The prevalence of int1 gene in clinical isolates of P . aeruginosa , is reported differently in similar investigations from Iran ranged from 43% to 56.3% [ 17 , 23 ], and around the world [ 6 , 15 , 24 ]. In mentioned reports and other documented studies, the prevalence is lower compared to the present study and this could be due to a trend of rapid increasing of integron positive rate among clinical isolates of P .…”

“…Dissemination of antibiotic resistance genes by mobile genetic elements is an increasing concern worldwide which can cause the evolution of multi-drug resistant (MDR) strains among clinical isolates [ 6 ].…”

Occurrence of Transferable Integrons and sul and dfr Genes Among Sulfonamide-and/or Trimethoprim-Resistant Bacteria Isolated From Chilean Salmonid Farms

“…Otherwise, while the occurrence of int2 gene in Pseudomonas aeruginosa has been previously reported (Xu et al, 2009; Goudarzi et al, 2015), none of the Pseudomonas strains included in this study were found to carry the int2 gene, which was in concordant to other reports of P. aeruginosa from clinical settings (Rossolini and Mantengoli, 2005; Sun et al, 2014; Khosravi et al, 2017). It must be noted that class 2 integrons are not usually detected in Pseudomonas strains from environmental sources, being most commonly associated with members of the family Enterobacteriaceae, such as E. coli and Salmonella enterica (Ahmed et al, 2005; Antunes et al, 2006; Cocchi et al, 2007; Essen-Zandbergen et al, 2007; Laroche et al, 2009; Ozgumus et al, 2009).…”

Characterization of integrons and novel cassette arrays in bacteria from clinical isloates in China, 2000-2014

“…Six studies claimed they found the novel gene cassette array which was not found in any species previously [ 4 , 7 – 8 , 20 , 33 , 54 ] . All the novel gene cassette arrays were detected from Gram-negative bacteria.…”