Molecular characterization of ESBL-producing Enterobacteriaceae in northern Portugal

Abstract

Extended-spectrum β-lactamases (ESBLs) prevalence was studied in the north of Portugal, among 193 clinical isolates belonging to citizens in a district in the boundaries between this country and Spain from a total of 7529 clinical strains. In the present study we recovered some members of Enterobacteriaceae family, producing ESBL enzymes, including Escherichia coli (67.9%), Klebsiella pneumoniae (30.6%), Klebsiella oxytoca (0.5%), Enterobacter aerogenes (0.5%), and Citrobacter freundii (0.5%). β -lactamases genes blaTEM, blaSHV, and blaCTX-M were screened by polymerase chain reaction (PCR) and sequencing approaches. TEM enzymes were among the most prevalent types (40.9%) followed by CTX-M (37.3%) and SHV (23.3%). Among our sample of 193 ESBL-producing strains 99.0% were resistant to the fourth-generation cephalosporin cefepime. Of the 193 isolates 81.3% presented transferable plasmids harboring bla ESBL genes. Clonal studies were performed by PCR for the enterobacterial repetitive intragenic consensus (ERIC) sequences. This study reports a high diversity of genetic patterns. Ten clusters were found for E. coli isolates and five clusters for K. pneumoniae strains by means of ERIC analysis. In conclusion, in this country, the most prevalent type is still the TEM-type, but CTX-M is growing rapidly.

Figure 1

Occurrence of ESBL-TEM, ESBL-SHV, and ESBL-CTX-M types in the north of Portugal. The present study, territory, Minho, is represented at the map in yellow. Other regions either from Portugal vs Spain are represented in different shades of green and gray or, respectively. Data was collected from the present study (yellow) and from several studies in these two countries [–, , , –26]. [ECO:Escherichia coli; ENT:Enterobacter spp.; KP:Klebsiella pneumoniae; K:Klebsiella spp.; SAL:Salmonella enterica].