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Rapid dissemination and diversity of CTX-M extended-spectrum beta-lactamase genes in commensal Escherichia coli isolates from healthy children from low-resource settings in Latin America.

Abstract：

:A survey carried out in 2005 among members of a healthy population of children living in Bolivia and Peru revealed that fecal carriage of Escherichia coli strains resistant to expanded-spectrum cephalosporins was remarkably increased compared to that observed in the same settings in 2002 (1.7% in 2005 versus 0.1% in 2002). In this work, we demonstrated that this phenomenon was mainly related to the dissemination of CTX-M-type extended-spectrum beta-lactamase (ESBL) determinants among commensal E. coli strains. Of 50 ESBL-producing isolates collected in the 2005 survey, 44 harbored a CTX-M-type and 6 an SHV-type (SHV-2 or SHV-12) ESBL. Compared to 2002 results, an increased diversity of CTX-M-type ESBLs was also observed: members of the CTX-M-1 group (CTX-M-15) emerged in Bolivia (where only CTX-M-2 was observed in 2002), while members of the CTX-M-9 group (CTX-M-14 and CTX-M-24) emerged in Peru (where only CTX-M-15 and CTX-M-2 were observed in 2002). A new CTX-M-2 variant named CTX-M-56 was also detected. Molecular characterization of the CTX-M-producing isolates and gene transfer experiments suggested that different mechanisms could be involved in the spreading of different CTX-M group determinants and revealed that additional resistance determinants for non-beta-lactam antibiotics were preferentially carried by plasmids encoding certain CTX-M variants (CTX-M-15 and variants of the CTX-M-2 group). Three CTX-M-15-encoding conjugative plasmids from Peruvian isolates carried the new fluoroquinolone resistance gene aac(6')-Ib-cr. To our best knowledge, this is the first report of the detection of aac(6')-Ib-cr in Latin America.

journal_name

Antimicrob Agents Chemother

journal_title

Antimicrobial agents and chemotherapy

authors

Pallecchi L,Bartoloni A,Fiorelli C,Mantella A,Di Maggio T,Gamboa H,Gotuzzo E,Kronvall G,Paradisi F,Rossolini GM

doi

10.1128/AAC.00026-07

subject

Has Abstract

pub_date

2007-08-01 00:00:00

pages

2720-5

issue

eissn

0066-4804

issn

1098-6596

pii

AAC.00026-07

journal_volume

pub_type

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Rapid dissemination and diversity of CTX-M extended-spectrum beta-lactamase genes in commensal Escherichia coli isolates from healthy children from low-resource settings in Latin America.