During the period March 2003 – May 2004 at the Laboratory of Clinical Microbiology “Redaelli” LTCRF in Milan, Italy, a total of 529 E. coli, obtained from inpatients of 3 different Long Term Care Rehabilitation Facilities (LTCRFs) in Northern Italy, were processed and 77 ESßLs producers (14.5%) were identified by Vitek System. The results were confirmed by double-disk synergy test with tazobactam (TZP). 61/77 isolates were characterized by higher levels of resistance to cefotaxime (CTX) than to ceftazidime (CAZ). (ß-lactamase production was investigated by analytical isoelectric focusing (IEF) coupled with a bioassay and showed multiple (ß-lactamase bands including one enzyme with pI 8.4 that, in a bioassay, was more active on CTX,ATM than on CAZ. The presence of (ß-lactamase genes was investigated by colony blot hybridization and by PCR amplification of blaTEM, blaSHV and blaCTX-M alleles. 43/61 isolates produced both TEM-1 and CTX-M-type enzymes, 14/61 expressed only CTX-M-type while in 4 cases were found blaCTX-M, blaTEM and blaSHV genes.The remainders (16/77), characterized by high levels of resistance to both CTX and CAZ, produced TEM-1 and SHV-5 enzymes (1/16) and TEM type ESßLs (15/16). Conjugation experiments, performed in liquid medium, confermed that the ESßLs determinants were transferable. Pulsed-field gel electrophoresis profiles of genomic DNA, digested with NotI, were analysed and revealed clonal heterogeneity. Our work confirms the emergence of CTX-M-type enzymes and their spread in Northern Italy also in longterm care and rehabilitation facilities that may be an important reservoir of ES?L producing E. coli.
Diffusione di Extended-Spectrum-ß-Lattamasi di tipo CTX-M in isolati clinici di E. coli provenienti da strutture di lungodegenza e riabilitazione geriatriche del Nord Italia
NUCLEO, ELISABETTA;MIGLIAVACCA, ROBERTA;SPALLA, MELISSA;PAGANI, LAURA
2008-01-01
Abstract
During the period March 2003 – May 2004 at the Laboratory of Clinical Microbiology “Redaelli” LTCRF in Milan, Italy, a total of 529 E. coli, obtained from inpatients of 3 different Long Term Care Rehabilitation Facilities (LTCRFs) in Northern Italy, were processed and 77 ESßLs producers (14.5%) were identified by Vitek System. The results were confirmed by double-disk synergy test with tazobactam (TZP). 61/77 isolates were characterized by higher levels of resistance to cefotaxime (CTX) than to ceftazidime (CAZ). (ß-lactamase production was investigated by analytical isoelectric focusing (IEF) coupled with a bioassay and showed multiple (ß-lactamase bands including one enzyme with pI 8.4 that, in a bioassay, was more active on CTX,ATM than on CAZ. The presence of (ß-lactamase genes was investigated by colony blot hybridization and by PCR amplification of blaTEM, blaSHV and blaCTX-M alleles. 43/61 isolates produced both TEM-1 and CTX-M-type enzymes, 14/61 expressed only CTX-M-type while in 4 cases were found blaCTX-M, blaTEM and blaSHV genes.The remainders (16/77), characterized by high levels of resistance to both CTX and CAZ, produced TEM-1 and SHV-5 enzymes (1/16) and TEM type ESßLs (15/16). Conjugation experiments, performed in liquid medium, confermed that the ESßLs determinants were transferable. Pulsed-field gel electrophoresis profiles of genomic DNA, digested with NotI, were analysed and revealed clonal heterogeneity. Our work confirms the emergence of CTX-M-type enzymes and their spread in Northern Italy also in longterm care and rehabilitation facilities that may be an important reservoir of ES?L producing E. coli.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
