Detection of CTX-M-14 b-lactamase in Escherichia coli from a long-term care and rehabilitation facility in northern Italy

Abstract number: 1732_278

Migliavacca R., Balzaretti M., Nucleo E., D'Andrea M.M., Mugnaioli C., Spalla M., Giani T., Rossolini G.M., Pagani L.

Objectives: The presence of ESBL producers (particularly among uropathogens) in geriatric long-term care and rehabilitation facilities (LTCRFs) has not been investigated in Italy, until now. The objective of this study was to evaluate the diffusion of CTX-M type b-lactamases among Escherichia coli clinical isolates from LTCRFs.

Methods: During the period April 2003–May 2004, a total of 529 E. coli consecutive non-replicated isolates were collected from inpatients at the LTCRF-RSA ASP ``Golgi-Redaelli'' of Milan. All isolates were identified and screened for ESBL production using the GNS-530 card of the VITEK 1 system, the double-disk synergy test and/or the confirmatory CLSI method. IEF coupled with a bioassay, PCR amplification and sequencing were carried out to identify the nature of the blaCTX-M-type determinants. Conjugation experiments, plasmidic DNA extraction followed by restriction analisys were also performed. The clonal relationships between the isolates were evaluated by PFGE of genomic DNA digested with NotI.

Results: All the E. coli clinical isolates resulted susceptible to piperacillin-tazobactam; 69/529 (13%) were ESBL producers. Such strains were obtained mainly from urinary samples (92.8%), in most cases from catheterised patients (90.6%). The CTX-M-type enzymes detected in 52/69 (75.4%) E. coli isolates showed a pI 8.2 or 8.4 active on cefotaxime, cefepime, and aztreonam. 40/52 (76.9%) CTX-M positive isolates were found to produce also a TEM-1 enzyme. The CTX-M determinants were transferable in 20/52 (38.4%) cases.

Sequencing results showed that 4/52 (7.7%) strains were CTX-M-14 producers while the remaining were CTX-M-1 producers. There was a common plasmid in 2/4 of the CTX-M-14 producers, both strains have been isolated from the Golgi institute. After plasmids restriction analysis, the CTX-M-1 coding plasmids exhibited different restriction profiles, while 2/4 CTX-M-14 producers resulted clonally related. PFGE profiles demonstrated the presence of at least 9 different clones.

Conclusions: Finding the different CTX-M-1-encoding plasmids in clonally related and unrelated strains of E. coli from the RSA ASP ``Golgi-Redaelli'' indicates a notable spreading potential for these plasmids and suggests that horizontal transfer could be the principal, but not the only mechanism of CTX-M enzymes spreading in the hospital environment. This is the first report of a CTX-M-14 gene in E. coli in Italy.

Session Details

Date: 31/03/2007
Time: 00:00-00:00
Session name: European Society of Clinical Microbiology and Infectious Diseases
Location: ICC, Munich, Germany
Presentation type:
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