Characterization of multi-drug resistant ESBL producing nonfermenter bacteria isolated from patients blood samples using phenotypic methods in Shiraz (Iran)

The emergence of nonfermenter bacteria that are resistant to multidrug resistant ESBL are nowadays a principal problem for hospitalized patients. The present study aimed at surveying the emergence of nonfermenter bacteria resistant to multi-drug ESBL producing isolated from patients blood samples using BACTEC 9240 automatic system in Shiraz. In this cross-sectional study, 4825 blood specimens were collected from hospitalized patients in Shiraz (Iran), and positive samples were detected by means of BACTEC 9240 automatic system. The isolates containing nonfermenter bacteria were identified based on biochemical tests embedded in the API-20E system. Antibiotic sensitivity test was performed and identification of ESBL producing strains were done using phenotypic detection of extended spectrum beta-lactamase producing isolates(DDST) according to CLSI(2013) guidelines. Out of 4825 blood samples, 1145 (24%) specimen were gram-positive using BACTEC system. Among all isolated microorganisms, 206 isolates were non-fermenting gram- negative bacteria. The most common non-fermenter isolates were Pseudomonas spp. (48%), Acinetobacter spp. (41.7%), and Stenotrophomonas spp. (8.2%). Seventy of them (81.4%) were Acinetobacter spp. which were ESBL positive. Among β-lactam antibiotics, Pseudomonas spp. showed the best sensitivity to piperacillin-tazobactam (46.5%). It was found that β-lactam antibiotics are not effective against more than 40% of Pseudomonas spp. infections and 78% Acinetobacter infections. Emergence of multi-drug resistant strains that are resistant to most antibiotic classes is a major public health problem in Iran. To resolve this problem using of practical guidelines is critical.