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

Abstract

Introduction: 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. Methodology: 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-molecularweight plasmids in both wild-type strains and E. coli transformants. Results: 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. Conclusions: 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.

Sites of colonization in hospitalized patients with infections caused by extended-spectrum beta-lactamase organisms: a prospective cohort study

“…This is in congruence with previous data from our center that showed CTX-M-15 to be the most common ESBL enzyme produced among E. coli and Klebsiella species [18]. High prevalence of the CTX-M gene has been described in various reports from different geographical regions including Europe [21], Asia [22], and the Americas [23]. Of interest is evidence suggesting that this enzyme is expressed in bacterial strains harbored by dogs, livestock, and birds [24, 25].…”

A Review of SHV Extended-Spectrum β-Lactamases: Neglected Yet Ubiquitous

“…A few variants seem to be geographically constrained: (i) bla SHV-106 , only described in Portuguese isolates of K. pneumoniae together with bla TEM-1 , and/or bla CTX- M -32 (Mendonça et al, 2009); (ii) bla SHV-55 , in Portugal (Mendonça et al, 2006; Machado et al, 2007) and recently in Brazil (Dropa et al, 2015); and (iii) bla SHV-57 , in E. coli isolates from Taiwan and China (Ma et al, 2005; Tian et al, 2012). A variant worth to mention is bla SHV-27 (Corkill et al, 2001), that has been detected on different plasmids in E. coli, K. pneumoniae and Enterobacter cloacae , associated with a vast array of antibiotic resistance genes ( bla DHA−1 , bla TEM-1 , bla TEM−1b , bla CMY-2 , bla IMP , bla CTX- M -14 , bla CTX- M -15 , bla SHV-12 , bla SHV-45 , bla OXA-1 , dfrA5, ereA2 ; Muratani et al, 2006; Abbassi et al, 2008; Kiratisin et al, 2008; Duval et al, 2009; Hammami et al, 2011).…”

“…These variants have been described worldwide (Brazil, Portugal, Algeria, USA, Tunisia, Netherlands, France, South Africa, Colombia, and China) and are mostly associated to plasmids (Table 1). Some of these variants are sporadically accompanied by other antibiotic resistance genes like in the case of: (i) bla SHV-45 encoded by an IncA/C plasmid together with bla CTX- M -2 and bla SHV-27 (Dropa et al, 2015); (ii) bla SHV-134 encoded by an IncFII plasmid accompanied by a second plasmid carrying bla VIM−1 (Sánchez-Romero et al, 2012); (iii) and bla SHV-105 , conferring reduced susceptibility to ceftazidime, ceftriaxone, and aztreonam together with bla SHV-1 , and bla SHV-5 (Jones et al, 2009). One of the oldest variants, bla SHV-6 , was only described in France in 1991 in a K. pneumoniae clinical case (Arlet et al, 1991).…”

Multidrug-resistant Gram-negative bacteria from patients, hospital environment and healthcare workers: a six-month cross-sectional study

“…The bla CTX-M-2 was identified with lower frequencies and only in E. coli , as previously reported (38, 45). However, other studies reported higher bla CTX-M-2 frequencies in Enterobacteriaceae, with results ranging between 52.3% and 89.3% (41, 42, 46). For the bla KPC-like we found a 6.4% frequency for Enterobacteriaceae and 33.3% for K. pneumoniae isolated from patients, in accordance with previous studies (38, 47-50).…”