CROMagar KPC evaluation for detection of carbapenemase-producing Enterobacteriaceae
Abstract number: P1627
Panayea F., Galani I., Adamou P., Souli M., Antoniadou A., Giamarellou H.
Objectives: Our aim was to compare CROMagar KPC with MacConkey agar with imipenem 1mg/mL for the detection of KPC and VIM producing Enterobacteriaceae strains from surveillance cultures.
Methods: 135 rectal swabs from 120 patients (78 ICU and 42 pathology/surgery wards) were tested. Swabs were plated on both MacConkey agar No3 + imipenem 1mg/mL (MC) and CROMagar KPC (Hy labs)(CR) and were incubated at 35°C, O2 for 48 h. Identification and antimicrobial susceptibility testing of all different colonies from MC and all different blue colonies from CR was performed by Phoenix (BD). Strains were screened for KPC and VIM by merop-merop+boronic acid and merop-EDTA, ceftaz-EDTA disc respectively and confirmed by PCR methodology. Isolation of Enterobacteriaceae on CR was also tested with known VIM + and KPC+ strains.
Results: Carbapenem resistant strains recovered from MC were: Kl. pneumoniae 44 (36 KPC+, 8 VIM+), Ps. aeruginosa 20, Pr. mirabilis 4, E. cloacae 1 (KPC+), E. aerogenes 1 (KPC+) and A. baumannii 21. CR recovered 54 carbapenemase producing Kl. pneumoniae strains (41 KPC+, 13 VIM+), isolated the first day of incubation. KPC+ strains were 100% non-susceptible to imipenem (MIC8) and 95.3% to meropenem (8) and VIM+ strains were 93.3% non-susceptible to imipenem and 46.7% to meropenem. Enterobacter spp. strains were not isolated, most probably due to the resemblance of their colonies to the coexisting Kl. pneumoniae strains. Ps. aeruginosa and A. baumannii strains exhibited white colonies. Pr. mirabilis strains were not recovered. Collectively, Kl. pneumoniae isolated strains were 43 KPC+ (34 both plates, 7 only CR, 2 only MC) and 15 VIM+ (6 both plates, 7 only CR, 2 only MC). Sensitivity of MC and CR for Kl. pneumoniae KPC+ strains was 83.7 and 95.3 and for VIM+ strains 53.3 and 86.6 respectively. All false (-) results on CR were due to the coexistence of VIM+ and KPC+ Kl. pneumoniae strains in the sample (same colonies). On the contrary, in 10 out of 14 false (-) results on MC there was no growth of lac(+) colonies, although strains' imipenem MIC was within non-susceptible range. MC and CR detected carbapenemase producing Kl. pneumoniaestrains with an overall sensitivity 81.5, 100 and specificity 100, 100 respectively.
Conclusion: CR detects with high sensitivity and specificity within 24 h either KPC or VIM producing Enterobacteriaceae strains in surveillance cultures, allowing immediate implementation of infection control measures to avoid spread of resistant clones.
|Session name:||Abstracts 20th European Congress of Clinical Microbiology and Infectious Diseases|
|Location:||Vienna, Austria, 10 - 13 April 2010|
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