Atypical epidemiology of CTX-M-15 among Enterobacteriaceae from a high diversity of non-clinical niches in Angola

• Published in: Journal of antimicrobial chemotherapy Vol. 71; no. 5; pp. 1169 - 1173
• Main Authors: Ribeiro, T G, Novais, Â, Peixe, L, Machado, E
• Format: Journal Article
• Language: English
• Published: England Oxford Publishing Limited (England) 01-05-2016
• Subjects: Angola; Animals; Antibiotics; Bacteria; beta-Lactamases - genetics; Cloning; Conjugation, Genetic; Electrophoresis, Gel, Pulsed-Field; Enterobacteriaceae - classification; Enterobacteriaceae - enzymology; Enterobacteriaceae - genetics; Enterobacteriaceae - isolation & purification; Environmental Microbiology; Epidemiology; Gene Transfer, Horizontal; Genes; Genotype; Healthy Volunteers; Humans; Microbial Sensitivity Tests; Multilocus Sequence Typing; Plasmids; Plasmids - analysis
• ISSN: 0305-7453; 1460-2091
• DOI: 10.1093/jac/dkv489

The objective of this study was to investigate the distribution and molecular epidemiology of ESBLs, acquired AmpCs and carbapenemases in Enterobacteriaceae from non-clinical niches in Angola, an under-researched sub-Saharan country.
Eighty-one samples were recovered from healthy persons (n = 18), healthy animals (n = 33) and their environments (n = 10) or aquatic settings (n = 20) in south Angola (2013). Samples were plated onto CHROMagar™ Orientation with/without antibiotics. Standard methods were used for bacterial identification, characterization of bla genes, antibiotic susceptibility testing and conjugation assays. Clonal analysis (XbaI-PFGE, MLST and Escherichia coli phylogroups), location of bla and plasmid characterization (S1-PFGE, I-CeuI-PFGE, replicon typing and hybridization) were also performed.
ESBLs (almost exclusively CTX-M-15, 98%) were detected in 21% (45/216) of the isolates, recovered from diverse non-clinical niches and belonging to different Enterobacteriaceae species (mainly E. coli). Acquired AmpCs or carbapenemases were not found. The pandemic B2-ST131 E. coli clone was not identified, but some widespread clonal complexes (CCs) from A (CC10 and CC168), B1 (CC156) or D (CC38) phylogroups were detected. blaCTX-M-15 was variably identified on typeable (29%; 100-335 kb; IncFII, IncFIIK6, IncHI2 and IncY) or non-typeable (16%; 70-330 kb) plasmids or on the chromosome (14%), while for 41% of the isolates its specific location was not determined.
This study reports, for the first time in Angola, an unexpected high occurrence of CTX-M-15 in diverse non-clinical niches and Enterobacteriaceae species, and uncovers novel plasmid replicons in under-researched geographical regions. The diffusion of blaCTX-M-15 through such a high diversity of genetic backgrounds (clones, typeable/non-typeable plasmids and genetic environments) unveils an extraordinary ability for blaCTX-M-15 acquisition and mobilization favoured by unrecognized ecological factors.