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Differences in the epidemiology of extended-spectrum beta-lactamase producing Escherichia coli according to the types of enzymes

Abstract number: o268

Rodríguez-Bano  J., Navarro  M.D., Romero  L., Muniain  M.A., Hernández-Bello  J.R., Pascual  A.

Objectives: 

Extended-spectrum beta-lactamase-producing Escherichia coli (ESBLEC) are an emergent cause of community and nosocomial infections. We analyse the epidemiology of ESBLEC in our area according to the type of ESBL produced.

Methods: 

All patients from whom an ESBLEC was isolated in our area (550,000 population) from January 2001 to May 2002 were included. The following data were collected: age, sex, chronic underlying diseases, previous health-care relation (HCR), invasive procedures, previous antimicrobial use, and types of infection. ESBL production and antimicrobial susceptibility were studied by microdilution (NCCLS guidelines). ESBLs were characterized by isoelectric focusing, PCR, and sequencing. Clonal relationships among the isolates were determined by REP-PCR.

Results: 

Ninety-six cases were included; 77% of them had previous HCR. Forty-nine (51%) were outpatients. Among these, 65% were being attended in primary care, 20% in the emergency service and 14% in the outpatient's clinic. The other 47 patients (49%) were hospitalized. Seventy-four (77%) were considered to have an infection: UTI, 66%; skin and soft tissues, 18%; primary bacteraemia, 10%; and respiratory tract, 6%. Seventy-two percent of the isolates produced one ESBL, 26% produced 2, and 2% produced 3; 63% of the isolates produced CTX-M enzymes (mainly CTX-M-14), 47% produced SHV (mainly SHV-12), and 21% TEM. Two homogeneous groups were identified for comparison: patients with isolates producing only CTX-M (n = 47) and those producing TEM + SHV but not CTX-M (n = 14). Significant differences were found in nosocomial acquisition (36% vs 100%, p < 0.001), non-fatal disease (70% vs 36%, p = 0.05), diabetes (49% vs 21%, p = 0.06), urinary catheter (32% vs 64%, p = 0.03), and fluoroquinolone use (30% vs 64%, p = 0.01). Isolates producing only CTX-M enzymes were more frequently susceptible to gentamicin (83% vs 43%, p = 0.01) and ciprofloxacin (24% vs 0, p = 0.05). There was no clonal relationship among the CTX-M-producing isolates, while those producing TEM + SHV belonged to 2 clonal groups.

Conclusions: 

There are significant differences in the epidemiology of ESBLEC according to the types of enzyme produced. Isolates producing CTX-M enzymes are most commonly community-acquired, are less frequently resistant to non-betalactams, and are not clonally related, while those producing TEM + SHV cause nosocomial outbreaks. These differences should be taken into account for the design of control measures.

Session Details

Date: 01/08/2007
Time: 00:00-00:00
Session name: XXIst ISTH Congress
Subject:
Location: Oxford, UK
Presentation type:
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