title: ESBL-producing Escherichia coli isolated from children with acute diarrhea - antimicrobial susceptibility, adherence patterns and phylogenetic background.
abstract: BACKGROUND
  Escherichia coli remains the principal bacterial pathogen in childhood diarrhea and constitutes an important public health problem, especially in developing countries. Diarrheagenic E. coli strains often display resistance to beta-lactams due to the production of extended-spectrum beta-lactamases (ESBLs).
  
  
  OBJECTIVE
  A total of thirty ESBL-producing E. coli strains colonizing the gastrointestinal tracts of children with acute diarrhea were studied in order to determine their antimicrobial susceptibility, adherence patterns to the HEp-2 cell line and phylogenetic background.
  
  
  METHODS
  ESBL production was detected by the double disk synergy test (DDST). The minimal inhibitory concentrations (MICs) of antibacterial drugs were determined by an agar dilution technique on Mueller-Hinton agar. The presence of bla(TEM), bla(SHV) and bla(CTX-M) determinants in the strains studied was ascertained by polymerase chain reaction (PCR).
  
  
  RESULTS
  The strains displayed the resistance pattern typical of ESBL producers. The majority of them (23 out of 30) were found to produce CTX-M-type ESBLs conferring a high level of resistance to oxyimino-beta-lactams, especially to cefotaxime and ceftriaxone. In many cases, the strains exhibited resistance to non-beta-lactam antimicrobials, such as gentamicin, amikacin, co-trimoxazole and tetracycline. On the other hand, these strains were uniformly susceptible to carbapenems, to oxyimino-beta-lactams combined with clavulanic acid and to tigecycline. The E. coli strains were distributed among the four main phylogenetic groups: A, B1, B2 and D. The in vitro adhesion assay revealed that all but two of the strains adhered to the HEp-2 epithelial cell line. Aggregative and diffuse adherence patterns were found to be the most prevalent.
  
  
  CONCLUSIONS
  CTX-M-type enzymes were the most prevalent ESBLs among the strains studied. As many as 40% of the diarrheagenic E. coli isolates were found to belong to phylogenetic group D, which usually comprises E. coli strains associated with extra intestinal infections. The effectiveness of tigecycline against ESBL-producing E. coli strains was similar to that of imipenem and meropenem.
authors.affiliation: Department of Microbiology, Wroclaw Medical University, Wrocław, Poland. roman.franiczek@am.wroc.pl
authors.forename: Roman
authors.initials: R
authors.lastname: Franiczek
authors.forename: Beata
authors.initials: B
authors.lastname: Sobieszczańska
authors.forename: Michał
authors.initials: M
authors.lastname: Turniak
authors.forename: Urszula
authors.initials: U
authors.lastname: Kasprzykowska
authors.forename: Barbara
authors.initials: B
authors.lastname: Krzyzanowska
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Jermakow
authors.forename: Grazyna
authors.initials: G
authors.lastname: Mokracka-Latajka
mesh_terms: D000208:Acute Disease; D000890:Anti-Infective Agents / Q000494:pharmacology*; D001422:Bacterial Adhesion; D002460:Cell Line; D002675:Child, Preschool; D003967:Diarrhea / Q000382:microbiology*; D004926:Escherichia coli / Q000145:classification / Q000187:drug effects / Q000201:enzymology / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification*; D004927:Escherichia coli Infections / Q000382:microbiology*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D005243:Feces / Q000382:microbiology; D006801:Humans; D007223:Infant; D008826:Microbial Sensitivity Tests; D010802:Phylogeny; D011044:Poland; D016133:Polymerase Chain Reaction; D018440:beta-Lactam Resistance / Q000235:genetics; D001618:beta-Lactamases / Q000235:genetics / Q000378:metabolism*
chemical_list: D000890:Anti-Infective Agents; D029968:Escherichia coli Proteins; D001618:beta-Lactamases