Complex class 1 integrons harboring CTX-M-2-encoding genes in clinical Enterobacteriaceae from a hospital in Brazil

• Published in: Journal of infection in developing countries Vol. 9; no. 8; pp. 890 - 897
• Main Authors: Dropa, Milena, Balsalobre, Livia Carminato, Lincopan, Nilton, Matté, Glavur Rogério, Matté, Maria Helena
• Format: Journal Article
• Language: English
• Published: Italy Journal of Infection in Developing Countries 29.08.2015
• Subjects: Bacterial Proteins - classification; Bacterial Proteins - genetics; beta-Lactamases - classification; beta-Lactamases - genetics; Brazil - epidemiology; Cross Infection - epidemiology; Cross Infection - microbiology; DNA Primers; DNA, Bacterial - analysis; Drug Resistance, Bacterial; E coli; Enterobacteriaceae - enzymology; Enterobacteriaceae - genetics; Enterobacteriaceae - isolation & purification; Enterobacteriaceae Infections - epidemiology; Enterobacteriaceae Infections - microbiology; Humans; Plasmids; Polymerase Chain Reaction; Brazil
• ISSN: 1972-2680; 2036-6590; 1972-2680
• DOI: 10.3855/jidc.6241

CTX-M enzymes are the most prevalent extended-spectrum beta-lactamases (ESBLs) in Brazil and around the world. The spread of CTX-M lies in their ability to be mobilized by insertion sequences and integrons. This study aimed to identify the mobile genetic structures associated with bla(CTX-M) genes from clinical Enterobacteriaceae strains. Twenty-eight clinical non-clonal Enterobacteriaceae were screened by PCR for the presence of bla(CTX-M) genes and class 1 integrase (int1), and for the association of bla(CTX-M) with class 1 integrons. Plasmid incompatibility groups were assessed by PBRT. Wild-type plasmids were transformed into electrocompetent E. coli, and the S1-PFGE technique was used to verify the presence of high-molecular-weight plasmids in both wild-type strains and E. coli transformants. Sequencing showed that strains carried bla(CTX-M-2) (n = 25) and bla(CTX-M-59) (n = 3) genes inserted into the 3'-end of complex class 1 integrons. Thirteen strains also carried bla(TEM) and bla(SHV) genes. CTX-M-2/59-containing complex class 1 integrons were also present in E. coli transformants. The most frequent Inc groups were IncA/C (n = 10) and IncF (n = 8). Heavy plasmids were observed in both wild-type strains and E. coli transformants. The presence of the same bla(CTX-M-2-group)-containing genetic structure in seven Enterobacteriaceae species isolated at seven hospital wards shows the great mobility potential of complex class 1 integrons. Also, this is the first report of TEM-15, SHV-45, and SHV-55 in Latin America. The genetic environment of bla(CTX-M-2) accounts for their maintenance and spread among Gram-negative bacteria.