Spread of CTX-M extended-spectrum b-lactamases among Escherichia coli and Klebsiella pneumoniae isolates in Italian long-term care facilities: results of the first nationwide prevalence study

Abstract number: P625

Pagani L., Migliavacca R., Spalla M., Saviane D., Regattin L., Botti V., De Luca C., Raglio A., Goglio A., Brusaferro S.

Objectives: In the present century CTX-M Extended-Spectrum Beta-Lactamases (ESBLs) have become predominant mainly in E. coli, and the producers are increasingly isolated from community patients. Over 60 different CTX-M-type enzymes have been identified from around the world. Reports of Italian isolates with CTX-M ESBLs only began to appear in 2003. The objective of this study was to evaluate the diffusion of CTX-M type b-lactamases among E. coli and K. pneumoniae clinical isolates recovered from Long-Term Care Facilities (LTCFs) residents across Italy.

Methods: All catheterised inpatients at the 37 facilities involved in the study were surveyed in the same day between Sept. 2006 and Jan. 2007. Susceptibility testing of urinary isolates was performed with VITEK 2 System (Bio-Mérieux). All isolates identified as ESBL producers according to CLSI criteria were tested at first for blaCTX-M alleles by PCR with universal primers. ESBL-CTX-M producers detected by phenotypic and genotypic methods were then investigated by using specific primers for various blaCTX-M groups. The clonal relationships between epidemiologically relevant E. coli and K. pneumoniae strains were evaluated by PFGE.

Results: A total of 496 Enterobacteriaceae isolates were recovered. The overall ESBL producers rate was 39.7%. All isolates were characterised by co-resistances but all retained susceptibility to carbapenems.

The prevalence rates of E. coli, the most frequent uropathogen, and of K. pneumoniae were 40.5% and 8.5% respectively. Seventy-two E. coli (35.8%) and ten K. pneumoniae (23.8%) produced ESBLs, with 75% and 60% respectively producing CTX-M enzymes. CTX-M-1-group ESBLs were the most prevalent in E. coli (49/54 strains) but CTX-M-9-group variants were also identified (5/54 strains). K. pneumoniae isolates produced CTX-M-1 group enzymes exclusively. The five E. coli CTX-M-9-type producers were from 4 LTCFs: two located in Southern Italy and the others in Northern Italy. E. coli CTX-M-9-type producers were clustered in three clonal lineages, one of which responsible for an epidemic in a LTCF in Catania.

Conclusions: Our data confirm that LTCFs are reservoirs of MDR pathogens and that CTX-M-type ESBLs are widespread also in these settings. The overall CTX-M producers rate in LTCFs is higher than that reported in the second Italian nationwide survey (2003) for isolates from acute-care hospitals. Our results document the dissemination of CTX-M-9-type genes also in Italian area.

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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