Linezolid Susceptibility Surveillance in Europe for 2013: ZAAPS Program (5,076 strains)

Results: LZD potency for indicated species in the ZAAPS Program was consistent across species (MIC 90 at 1 mg/L), see Table. Nearly all MIC values for LZD were 0.5, 1 or 2 mg/L. One LZD-R isolate was detected among SA which contained the cfr gene. LZD-R strains were also detected in the CoNS group (2 S. epidermidis) both with G2576T mutations (1 strain with the L3 mutation M156R and 1 strain with L3 mutation M156T). These countries had LZD-R strains: Italy (Genova; 2 S. epidermidis strains) and Spain (Madrid; S. aureus) with LZD-R MIC values at 8-32 mg/L. Agents other than LZD with >90% S rates versus SA were: clindamycin (90.3), gentamicin (95.6%), tetracycline (93.0%), teicoplanin (100.0%), trimethoprim/sulfamethoxazole (99.5%) and vancomycin (100.0%). MRSA rates varied greatly among countries. Six countries exhibited rates greater than 40%, four countries rates between 20-30%, eight countries between 1020% and two countries (Sweden and Slovenia) less than 10%. Sweden had the lowest rate (0.6%, 1/177) and Portugal the highest (78.1%, 57/73). Erythromycin-R and clindamycin-R rates among MRSA were 72.1% and 33.7%, respectively. The vancomycin-non-susceptible rate for Enterococci was 12.2%. LZD was active against all streptococci with an MIC 90 , of 1 mg/L. Penicillin-R rate for SPN was 12.0% and ceftriaxone–non-S for SPN was 4.7% (CLSI criteria) or 14.0% (EUCAST criteria). Conclusions: LZD-R rate for 2013 EU ZAAPS Program was only 0.06% and showed no escalation of R compared to previous reports from the ZAAPS programs. LZD-R occurrences were among CoNS and SA, which included one acquired cfr gene among the 3,041 staphylococci screened in EU. • Linezolid activity in monitored European medical centers remains stable by covering nearly all strains (99.94% susceptible); and resistance continues to be most common among staphylococci (CoNS>S. aureus) and enterococci (none in 2013 at ≥4 mg/L) isolates. • Epidemic or endemic occurrences of linezolid-resistant strains have become more common in some European medical centers, especially in Italy (Catania, Genova, Rome) and Spain (Madrid).