Identification of ESBL-producing and blaSHV gene Harboring Enterobacter spp. Isolated from Bloodstream Infections of Hospitalized Patients During 10 Years in South of Iran (Shiraz)

Multidrug resistance is emerging among gram negative bacteria that cause hospital infections or community acquired around the world. The aims of this study were (1) determination of antibiotic susceptibility profile of Enterobacter spp. isolates recovered from blood, (2) phenotypic identification of ESBL and AmpC-producing isolates, (3) identify MDR strains, and (4) identification isolates harboring blaSHV gene using PCR method.
In this cross-sectional study, 90 isolates of Enterobacter spp. isolated from blood stream infection from patients admitted to hospitals in Shiraz using BACTEC 9240 automated system during 10 years (2004-2014). The isolates again were identified by using embedded biochemical tests in the Enterobacteriaceae API-20E diagnostic system. According to proposed protocol by CLSI (2014), standard disc diffusion method and DDST phenotypic test were used for antibiotic susceptibility test, and identification of ESBL-producing strains, respectively. PCR molecular method was used to identify blaSHV gene in strains.
In this study, as observed, meropenem (98.9%), imipenem (95.6%) and colistin (93.3%) were the most effective antibiotics against isolates. Isolates showed the best response to ceftazidime (47.8%) and ceftriaxone (42.2%), respectively, among the third generation of cephalosporins which were investigated. Results showed that 11.1% of isolates were MDR. 15.5% isolates were positive ESBL and positive AmpC, simultaneously. As revealed, 11.1% of isolates were MDR. The results of PCR to search for blaSHV gene in Enterobacter isolates revealed that 7.8% of the strains harboring this gene.
Results showed that the resistance of Enterobacter isolates to the third generation of cephalosporins has become a national health-threatening problem. Epidemiologic studies are crucial in order to presentation of comprehensive national program to preventing emergence and dissemination of resistant bacteria in the country. We believe that carbapenems should be used for the treatment of strains resistant to other antibiotics in order to preservation of carbapenems as strategies for the treatment of Enterobacter spp.