Five years of Belgian MIST (meropenem information on bacterial susceptibility testing) surveillance: 2001–2005

Abstract number: P661

Govaerts D., Coppens G., Fameree D., Masschelin B., Meunier F., Sion C., Turner P., Vandenhoven G.

Objectives: The activity of meropenem and 6 comparators was studied in the MIST trial, on a total of 2.553 isolates (706 Gram-positives and 1.847 Gram-negatives) from 6 general non teaching hospitals in Belgium, collected from 2001 to 2005.

Materials and Methods: Centres collected consecutively up to 50 and 75 unduplicated, aerobic Gram+ and Gram- isolates respectively from patients admitted in ICU, haematology and general wards. CLSI methods and E-tests were used for susceptibility testing. ESBL and AmpC production were confirmed by at least a geqslant R: gt-or-equal, slanted3log2 reduction in ceftazidime MIC in the presence of clavulanate and a ceftazidime MIC > 8mg/l not lowered by the presence of clavulanate respectively.

Results:S. aureus (n = 237) was the most frequently isolated Gram+ bacteria with 98–100% susceptibility for the carbapenems. Among the Enterobacteriaceae (n = 1371), meropenem was the most active antibiotic (99.9%), followed by imipenem (98.5%), cefepime (98.3%) and amikacin (93.1%). Lower susceptibility rates were observed for piperacillin–tazobactam (83.1%), ceftazidime (80.2%) and ciprofloxacin (75.8%). More than 50% of E. aerogenes isolates (n = 232) were resistant to ceftazidime, piperacillin–tazobactam and ciprofloxacin, while the carbapenems and cefepime were extremely active (>95% susceptibility). Susceptibility rates among all Enterobacteriaceae remained stable for all antibiotics tested between 2001 and 2005. The prevalence of ESBL-producing isolates varied from 1.7 to 3.9% for all Enterobacteriaceae, from 0 to 4.3% for E. coli (n = 322), 0 to 9.5% for K. pneumoniae (n = 160) and 0 to 4.9% for E. aerogenes. The prevalence of AmpC producers among E. aerogenes isolates varied from 0 to 42%. Susceptibilities of ESBL and AmpC producers to carbapenems varied between 98–100%.

Against P. aeruginosa isolates (n = 273), the rank order of susceptibilities during the study period was: meropenem (88.3%), ceftazidime (87.9%), piperacillin–tazobactam (86.1%), amikacin (85.7%), imipenem (84.2%), cefepime (77.9%) and ciprofloxacin (76.9%). Susceptibility rates for P. aeruginosa remained stable for all antibiotics tested, excepted cefepime, which declined between 2001 and 2005.

Conclusions: During the study period, the carbapenems and cefepime were the most active agents against the Enterobacteriaceae, including ESBL and/or AmpC producers. Meropenem and ceftazidime were the most active agents against P. aeruginosa.During 5 years of Belgian MIST surveillance, susceptibility rates for meropenem remained stable.

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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