title: SHV-type extended-spectrum beta-lactamase (ESBL) are encoded in related plasmids from enterobacteria clinical isolates from Mexico.
abstract: OBJECTIVE
  In this work we report the molecular characterization of beta-lactam antibiotics resistance conferred by genes contained in plasmids from enterobacteria producing extended-spectrum beta-lactamases (ESBL).
  
  
  METHODS
  Fourteen enterobacterial clinical isolates selected from a group of strains obtained from seven different hospitals in Mexico during 1990-1992 and 1996-1998 were analyzed at the Bacterial Resistance Laboratory (National Institute Public Health, Cuernavaca). Molecular characterization included PFGE, IEF of beta-lactamases, bacterial conjugation, PCR amplification and DNA sequencing, plasmid extraction and restriction.
  
  
  RESULTS
  Isolates were genetically unrelated. ESBL identified were SHV-2 (5/14) and SHV-5 (9/14) type. Cephalosporin-resistance was transferable in 9 of 14 (64%) clinical isolates with only one conjugative plasmid, DNA finger printing showed a similar band pattern in plasmids.
  
  
  CONCLUSIONS
  The dissemination of cephalosporin resistance was due to related plasmids carrying the ESBL genes.
authors.affiliation: Departamento de Resistencia Bacteriana, Centro de Investigaciones Sobre Enfermedades Infecciosas, Instituto Nacional de Salud Pública, Mexico.
authors.forename: Ulises
authors.initials: U
authors.lastname: Garza-Ramos
authors.forename: Esperanza
authors.initials: E
authors.lastname: Martínez-Romero
authors.forename: Jesús
authors.initials: J
authors.lastname: Silva-Sánchez
mesh_terms: D001426:Bacterial Proteins / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D003428:Cross Infection / Q000453:epidemiology / Q000382:microbiology*; D016172:DNA Fingerprinting; D004269:DNA, Bacterial / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000382:microbiology*; D029968:Escherichia coli Proteins / Q000145:classification / Q000235:genetics / Q000302:isolation & purification; D006801:Humans; D007709:Klebsiella / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D007710:Klebsiella Infections / Q000453:epidemiology / Q000382:microbiology*; D008800:Mexico / Q000453:epidemiology; D011815:R Factors / Q000235:genetics*; D018440:beta-Lactam Resistance / Q000235:genetics*; D001618:beta-Lactamases / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; C062760:beta-lactamase SHV-2; C117193:beta-lactamase SHV-5; D001618:beta-Lactamases