Molecular detection of ESBL-producing Enterobacteriacee in northeastern Italy

Abstract number: R2304

Busetti M., Comar M., Fiermonte F., Campello C.

Objectives: The prevalence of extended spectrum b-lactamases (ESBL), especially the CTX-M type, increased dramatically during the past 10 years. Moreover, a molecular epidemiology shift was observed in Europe from TEM and SHV types to the predominant CTX-M enzyme. Among ESBL producers, E. coli emerged as a cause of urinary tract infections either in hospital or community settings.

Aim of this study was to assess by molecular methods the prevalence of different enzymes among ESBL-producing Enterobacteriacee in Trieste, North-Eastern Italy.

Methods: During 2007 we analysed 80 ESBL-producing bacteria (70 E. coli, 5 K. pneumoniae and 5 K. oxytoca) isolated from urinary tract (n= 60), respiratory tract (n = 6), blood (n = 5) or various other sites (n = 13). 57 strains were isolated from hospitalised patients and 23 from outpatients.

E. coli was recovered in 65 cases (92.8%) from adult patients, 43 hospitalised and 22 outpatients, while the majority of Klebsiella spp. (7 out of 9) were isolated in paediatric patients.

Identification and screening for ESBL was performed with VITEK 2 ID-GN and AST-N041cards. All isolates tested positive were confirmed by ESBL Etest strips with cefotaxime/ cefotaxime+clavulanate and ceftazidime/ ceftazidime+clavulanate. The confirmed isolates were examined by PCR for the presence of ESBL-encoding genes blaTEM, blaSHV and blaCTX-M, according to Mugnaioli et al (Antimicrob Agents Chemother, 2006).

Results: Of the 70 ESBL-producing E. coli, 61 (87.1%) were positive for blaCTX-M, alone (30, corresponding to 42.8%) or in combination with blaTEM (31, 44.3%). Only 8 isolates showed other resistance genes (1 blaTEM alone, 1 blaSHV and 7 with associated blaTEM and blaSHV). In K. pneumoniae, bla SHV was present in all 5 isolates, alone (n = 1) or associated with blaTEM (n = 2) or blaTEM and CTX-M (n = 2). In K. oxytoca, 3 strains carried blaSHV and 1 blaTEM, while bla CTX-M was absent; only one strain resulted negative for all the ESBL tested.

Conclusion: In our area, ESBL-producing Klebsiella spp. are rarely detected, while E. coli is becoming the predominant ESBL-producing species, as reported in other Italian areas and other European countries. Among ESBL-positive Enterobacteriacee, CTX-M type is most frequently encountered, involving about 87% of E. coli strains. Finally, ESBL resistance is not exclusively found in hospital settings, but it is spreading even in the community, involving especially elderly patients with urinary tract infection.

Session Details

Date: 19/04/2008
Time: 00:00-00:00
Session name: 18th European Congress of Clinical Microbiology and Infectious Diseases
Location: Barcelona, Spain
Presentation type:
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