Isolation and Identification of Carbapenemase KPC Producing Strains of Enterobacteriaceae and Determination of Their Antibiotic Susceptibility Patterns

The aim of this study was to isolate and identify KPC (Klebsiella pneumonia carbapenemase) enzyme producing strains of Enterobacteriaceae، and determine their antibiotic susceptibility pattern in three hospitals of Isfahan، Iran. This subject has not previously been investigated comprehensively. KPC detection was done by Modified Hodge Test (MHT) and their antibiotic susceptibility patterns were determined by disc diffusion method. The total of 475 strains were isolated and detected as Enterobacteriaceae during the period of 9 months (July 2012-March 2013) in three hospitals in Isfahan province، Iran. These isolates contained Escherichia coli: 285 strains (60%)، Klebsiella: 128 strains (27%)، Enterobacter aerogenes: 16 strains (3. 4%)، Enterobacter cloacae: 9 strains (1. 9%)، Proteus vulgaris: 12 strains (2. 5%)، Proteus mirabilis: 4 strains (0. 84%)، Citrobacter freundii: 8 strains (1. 7%)، Citrobacter diversus: 3 strains (0. 6%)، Serratia marcescens: 3 strains (0. 6%)، Shigella sonnei: 4 strains (0. 84%)، Salmonella paratyphi A: 2 strains (0. 42%)، and Providencia stuartii: 1 strain (0. 2%). Percentage resistant to ceftazidime and cefotaxime and non-susceptibility to imipenem and meropenem for above isolates were، respectively، as follows: for Escherichia coli isolates 60، 63، 6، and 9; for Klebsiella isolates 70، 75، 55، and 58; for Klebsiella pneumoniae 100، 100، 95، and 94; and for other Enterobacteriaceae isolates 20، 17، 5، and 3. Our results showed that KPC test was positive for 2 isolates (0. 7%) among Escherichia coli strains، 65 (87%) isolates among Klebsiella pneumoniae، and 1 isolate (6%) among Proteus strains. This was approved by Etest based MIC method. In general، our results showed that among Enterobacteriaceae isolates، Klebsiella pneumoniae isolates had higher KPC enzyme production، and most strains had multidrug resistant.