title: Intestinal Colonization by Extended-Spectrum Beta-Lactamase-Producing Enterobacteriaceae in Infants.
abstract: BACKGROUND
  Members of the Enterobacteriaceae family are common agents of nosocomial infections. Intestinal colonization by these microorganisms represents a major step in the development of systemic infection. Extended-spectrum b-lactamase-producing bacteria are usually associated with outbreaks, but endemic infections are common in intensive care units.
  
  
  OBJECTIVE
  To determine the frequency of intestinal colonization with extended-spectrum b-lactamase-producing Enterobacteriaceae in newborns.
  
  
  METHODS
  This was a descriptive cohort study. Newborns from two general hospitals (A and B) in Mexico City were included during a five-month period; those with a hospital stay > 7 days were selected. Fecal samples were obtained by rectal swab on day 7 and every week until discharge. Extended-spectrum b-lactamase production was confirmed in enterobacteria by the Etest. Clonal relatedness was established by pulsed-field gel electrophoresis.
  
  
  RESULTS
  102 newborns were included; 63/102 (61.7%) were colonized by extended-spectrum b-lactamase-producing Enterobacteriaceae on day 7, 17/21 (81%) on day 14, and 6/8 (75%) on day 21 of hospitalization. Klebsiella pneumoniae was recovered most frequently (75.4%). A predominant clone (95%) was found in hospital B, and a major clone (75%) in Hospital A. Other extended-spectrum b-lactamase-producing Enterobacteriaceae isolates were Enterobacter spp. (16%) and Escherichia coli (7.6%).
  
  
  CONCLUSIONS
  High rates of colonization and horizontal transmission of extended-spectrum b-lactamase-producing Enterobacteriaceae were found in the newborn care units of two general hospitals. Clonal relatedness was identified. Lack of adherence to standard precautions and hand hygiene were determining factors.
authors.affiliation: Department of Infectious Diseases, Hospital de Pediatría, Centro Medico Nacional Siglo XXI, IMSS, México D.F, México.
authors.forename: Gloria Concepción
authors.initials: GC
authors.lastname: Huerta-García
authors.affiliation: Medical Research Unit in Hospital Epidemiology, Coordinación de Investigación en Salud, IMSS, México D.F, México.
authors.forename: Guadalupe
authors.initials: G
authors.lastname: Miranda-Novales
authors.affiliation: Coordinación de Unidades Medicas de Alta Especialidad, IMSS, México D.F, México.
authors.forename: Rita
authors.initials: R
authors.lastname: Díaz-Ramos
authors.affiliation: Department of Infectious Diseases, Hospital de Pediatría, Centro Medico Nacional Siglo XXI, IMSS, México D.F, México.
authors.forename: Guillermo
authors.initials: G
authors.lastname: Vázquez-Rosales
authors.affiliation: Department of Infectious Diseases, Hospital de Pediatría, Centro Medico Nacional Siglo XXI, IMSS, México D.F, México.
authors.forename: Fortino
authors.initials: F
authors.lastname: Solórzano-Santos
mesh_terms: D015331:Cohort Studies; D003428:Cross Infection / Q000453:epidemiology* / Q000382:microbiology; D016521:Electrophoresis, Gel, Pulsed-Field; D004755:Enterobacteriaceae / Q000201:enzymology / Q000302:isolation & purification*; D004756:Enterobacteriaceae Infections / Q000453:epidemiology* / Q000382:microbiology; D005260:Female; D006769:Hospitals, General; D006801:Humans; D007231:Infant, Newborn; D007363:Intensive Care Units, Neonatal; D007422:Intestines / Q000382:microbiology; D008297:Male; D008800:Mexico; D001618:beta-Lactamases / Q000096:biosynthesis*
chemical_list: D001618:beta-Lactamases