Results from the meropenem yearly susceptibility test information collection (MYSTIC) programme: report from two Croatian hospitals

Abstract number: r1936

Bedenic  B., Tonkic  M., Goic-Barisic  I., Mihaljevic  L., Bubonja  M., Suto  S., Kalenic  S., Punda-Polic  V., Bosnjak  Z.


Meropenem Yearly Susceptibility test Information Collection (Mystic) Programme is a global, longitudinal resistance surveillance network that monitors the activity of meropenem, only in selected centres that are prescribing meropenem.

We now report the four years period results (2002-2005) for the antimicrobial potency of meropenem compared to other agents, from the two Croatian Hospitals.

Materials and methods: 

The 2 hospitals in Croatia (Clinical Hospital Center Zagreb and University Hospital Split) participate in the MYSTIC Programme. The minimum-inhibitory concentrations (MICs) were determined by broth microdilution method according to NCCLS.


There was no resistance to either imipenem or meropenem observed for E. coli, K. pneumoniae and Proteus mirabilis in both medical centres. E. coli strains from Split were more resistant to ceftazidime (8%) and cefepime (4%) than those from Zagreb (1%, and 0.7%, 2% respectively) whereas isolates from Zagreb were more resistant to ciprofloxacin (7%) and gentamicin (13%) compared to those from Split (2% and 12% respectively). There was a higher percentage of resistance among K. pneumoniae isolates in comparison to E. coli from both centers to ceftazidime (28% from Zagreb and 44% from Split) and to cefepime (14% from Zagreb and 20% from Split). Genamicin and ciprofloxacin were also less active against K. pneumoniae from both centres (28% strains resistant to gentamicin from Zagreb and 37% from Split, 10% of the strains resistant to ciprofloxacin from Zagreb and 8% from Split). Meropenem was the most potent agent against A. baumannii and P. aeruginosa strains from both centres. There was a high percentage of A. baumanii strains from Split resistant to all beta-lactam agents (above 80%). More P. aeruginosa strains from Zagreb were resistant to gentamicin and ciprofloxacin compared to those from Split. Imipenem showed best activity against Gram-positive cocci from both centres.


According to our results meropenem remains the antibiotic of choice for the treatment of severe infections caused by Gram-negative bacteria. Resistance to carbapenems observed in some P. aeruginosa strains could be due to production of metallo-beta-lactamases, which are already detected in some of our strains (unpublished data), alterations in outer membrane proteins and efflux. Carbapenem resistance found in A. baumannii isolates from Split could be explained by the production of oxacillinases (unpublished data).

Session Details

Date: 01/08/2007
Time: 00:00-00:00
Session name: XXIst ISTH Congress
Location: Oxford, UK
Presentation type:
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