High prevalence of B2-ST131 clonal group among extended-spectrum ß-lactamase-producing Escherichia coli isolated from bloodstream infections in Quito, Ecuador.

OBJECTIVES: The purpose of this study was to describe the clonal relationships and phylogroups of extended-spectrum ß-lactamase-producing Escherichia coli (ESBL-Ec) isolated from patients with bacteraemia in three hospitals in Quito, Ecuador. METHODS: Between June 2013 and September 2014, a total of 4354 blood cultures were performed in three hospitals located in different areas of Quito. A BACTECTM system was used for blood culture, and the VITEK®2 system was used for species identification and in vitro antimicrobial susceptibility testing. The ESBL genotype, presence of the blaCTX-M, blaTEM and blaSHV genes, and the phylogenetic group of E. coli isolates was determined by PCR. Clonal groups were established by multilocus sequence typing (MLST). RESULTS: Of 929 blood cultures positive for Gram-negative bacilli, 181 (19.5%) were positive for E. coli, representing the most frequent bacteraemia isolates in each hospital. Of the 181 E. coli isolates, 57 (31.5%) were ESBL-Ec. The main sources of ESBL-Ec bacteraemia were urinary tract infection (40; 70.2%), biliary tract infection (10; 17.5%) and other infections (7; 12.3%). The majority of ESBL-Ec isolates (39; 68.4%) from the three hospitals belonged to the virulent phylogenetic group B2, of which 36/39 (92.3%) were ST131 and 33/36 (91.7%) carried the blaCTX-M-15 gene. CONCLUSION: These results provide knowledge of the phylogenetic relationships of E. coli from bacteraemia in Ecuadorian patients. ST131 has emerged in ESBL-Ec, representing an important public-health problem because this multiresistant clone is considered to be a vehicle for the propagation of antimicrobial resistance genes and is a highly virulent, well-adapted human pathogen.

Draft genome sequence of Enterobacter cloacae ST520 harbouring blaKPC-2, blaCTX-M-15 and blaOXA-17 isolated from coastal waters of the South Atlantic Ocean.

OBJECTIVES: Aquatic environments have contributed to the dissemination of multidrug-resistant (MDR) bacteria, representing a risk for humans and animals. The aim of this study was to report the first draft genome sequence of a MDR Enterobacter cloacae strain recovered from seawater in a public beach in Brazil. METHODS: The genome was sequenced on an Illumina MiSeq platform. De novo genome assembly was performed using SPAdes 3.10.1 and the whole genome sequence was analysed using bioinformatics tools from the Center of Genomic Epidemiology. RESULTS: This draft genome resulted in 5 228 857bp with 5331 protein-coding sequences, revealing the presence of blaKPC-2, blaCTX-M-15 and blaOXA-17 genes, responsible for resistance to all ß-lactam antibiotics. In addition, the strain was assigned to sequenced type 520 (ST520). CONCLUSION: These data provide useful information for comparative genomic analysis regarding the dissemination of antibiotic resistance genes.

Allodemic distribution of plasmids co-harbouring blaCTX-M-15/aac(6')-Ib-cr/qnrB in Klebsiella pneumoniae is the main source of extended-spectrum ß-lactamases in Uruguay's paediatric hospital.

OBJECTIVES: This study aimed to describe the characteristics of clinical isolates of extended-spectrum ß-lactamase (ESBL)-producing enterobacteria (EPE) in Uruguay's paediatric hospital. METHODS: ESBLs, qnr alleles and aac(6')-Ib-cr were sought and characterised in EPE isolated between March 2010 and March 2012. Transfer of resistance determinants was assessed by conjugation. Incompatibility (Inc) groups, plasmid toxin-antitoxin systems (TAS) and plasmid size were determined in transconjugants. Clonality was analysed by pulsed-field gel electrophoresis. Multilocus sequence typing was done for ESBL-producing Klebsiella pneumoniae. RESULTS: A total of 77 EPE isolates were characterised, comprising 43% K. pneumoniae, 19.5% Serratia marcescens, 19.5% Escherichia coli, 17% Enterobacter cloacae and 1% Klebsiella oxytoca. ESBLs belonged mainly to the blaCTX-M family (69.6%) [blaCTX-M-15 (45%) and blaCTX-M-2 (31%)]. The aac(6')-Ib-cr/qnrB duplex was the most frequently detected plasmid-mediated quinolone resistance mechanism; this association was detected in K. pneumoniae harbouring blaCTX-M-15. Transconjugants were obtained for 71% of the EPE. Amongst transconjugants, certain combinations were found between ESBLs and Inc group, e.g. IncA/C-blaCTX-M-2, IncHI1/HI2-blaCTX-M-9 and IncHI1/HI2-blaSHV-12. In addition, the combination ccdAB-blaCTX-M-15 was also found. K. pneumoniae isolates harbouring blaCTX-M-15/aac(6')-Ib-cr/qnrB showed allodemic behaviour, with a predominance of ST14, ST45 and ST48. CONCLUSIONS: In this study, epidemiological changes in ESBL distribution could be explained by the spread of K. pneumoniae harbouring blaCTX-M-15/aac(6')-Ib-cr/qnrB, encoded mainly on conjugative plasmids featuring ccdAB TAS. Since reports of TAS in K. pneumoniae plasmids are scarce, new strategies are needed to combat intrinsic selection pressure exerted by the association, in conjugative plasmids, of resistance mechanisms with TAS.

Draft genome sequence of a CTX-M-15-producing Klebsiella pneumoniae sequence type 340 (clonal complex 258) isolate from a food-producing animal.

Klebsiella pneumoniae carrying blaCTX-M-15 have been widely disseminated in hospital settings. In this regard, most clinically important strains belong to clonal complex 28 (CC258), which includes sequence type 340 (ST340). In this study, we present the draft genome sequence of a CTX-M-15-producing ST340 K. pneumoniae strain isolated from a food-producing animal in Brazil.