Increase of resistance to glycopeptides and epidemiological changes among nosocomial enterococci detected during 2007 in a Portuguese hospital

Abstract number: O516

Almeida F., Fernándes F., Carvalho S., Ferreira T., Mato R.

Objectives: To monitor the prevalence and epidemiology of glycopeptide resistant (GR) and high-level gentamicin resistant (HLGR) Enterococcus faecalis (Efl) and E. faecium (Efm) in a Lisbon hospital during the first semester of 2007. To compare the results with data obtained during year 2006.

Methods: Microbial identification and antimicrobial susceptibility were performed with the VITEK 2 system. GR and HLGR Efl and Efm were confirmed by PCR detection of vanA/B and aac(6')-aph(2") genes. Other aminoglycoside resistance genes (aph(2")-Ib, aph(2")-Ic, aph(2")-Id) and virulence genes (cylA, asaI, gelE, hyl) were detected by Multiplex-PCR. Clonal relationships were assigned by PFGE and virulence profiles. Multilocus sequence typing was performed among GR isolates.

Results: A total of 138 enterococci were collected in the first semester of 2007: 73% Efl, 26% Efm, and 1% E. casseliflavus. 6% of Efl and 14% of Efm were GR and approx. 46% were HLGR. Most (>80%) Efl were resistant to erythromycin, quinupristin-dalfopristin-Q/D and tetracycline-TE, 50% to ciprofloxacin-CIP, and 0% to ampicillin-AMP. One and 11 Efl were resistant and intermediate to linezolid, respectively. Comparing with Efl, Efm were resistant to AMP/CIP (100%) and resistance to TE (33%) and Q/D (5%) was lower. Only the aac(6')-aph(2") genes were detected (56 out of 63 HLGR). GR-Efl (n = 6) and GR-Efm (n = 5) were vanA-genotype. HLGR/GR-Efl (n = 45) were of 9 PFGE patterns, 6 of them not identified in 2006. PFGE-AO was prevalent (36 isolates) associated with genotypes cylA-asaI-gelE-esp (33%), cylA-asaI-gelE (28%), asaI-gelE (17%) and asaI-gelE-esp (11%). GR-Efl belong to the lineage ST6 (PFGE AO/cylA-asaI-gelE-esp or cylA-asaI-gelE). HLGR/GR Efm (n = 18) were of 10 PFGE patterns of which 5 were co-dominant (11 isolates). Distribution of virulence genes by proportion of PFGE patterns was: esp-45%; 22%-hyl/esp; 11%-hyl and 22% without virulence genes detected. GR-Efm belong to lineages ST17 (PFGE-x/hyl-esp), ST18 (PFGE-d/hyl-esp) and ST125 (PFGE-d/hyl).

Conclusions: Enterococcal infections increased in 2007 (138 isolates in 6 months), comparing with 2006 (171 isolates in 12 months) and GR increased from 3% to 9%. PFGE AO remains prevalent but carriage of the esp gene decreased from 90% to 40%. New Efm clones with different genetic backgrounds emerged in 2007 indicating the need for active surveillance in this particular hospital as well as in other Portuguese hospitals where a similar trend may be observed.