Identification of different species of Acinetobacter Strains, and determination of their antibiotic resistance pattern and MIC of Carbapenems by E-Test

The Gram-negative emerged an important nosocomial pathogen, especially in intensive care units. These bacteria are cause of health infections, specifically in intensive care units (ICUs). Recent reports present an increase in acinetobacters resistance to carbapenems. This study set out to determine the antibiotic resistance pattern and minimum inhibitory concentration (MIC) of carbapenems in different species of acinetobacters isolated from clinical specimens of Shahid Mohammadi Hospital in Bandar Abbas.
This descriptive-cross sectional study investigated 81 acinetobacter isolates, collected from different clinical specimens, to the species level, using biochemical tests and Microgen GNA-ID System. The antibiotic resistance pattern of the species was screened by the Kirby-Bauer method performed on Mueller–Hinton agar. In addition, the MIC of imipenem and meropenem antibiotics was evaluated using E-test.
Among the investigated 81 acinetobacter species, 79 (97.5%), 1, and 1 species were of acinetobacter baumannii, acinetobacter lwoffii, and acinetobacter haemolyticus families, respectively. According to the Kirby-Bauer method, the maximum antibiotic resistance of acinetobacter baumannii was to ceftriaxone (98.73%), ciprofloxacin (96.20%), and imipenem (82.28%); in addition, the maximum sensitivity was to polymyxin B and colistin (97.5%), and tigecycline (82.28%). Determination of the minimum inhibitory concentration with R-test showed that 79.75% and 78.48% of acinetobacter baumannii strains were resistant to imipenem and meropenem, respectively. The acinetobacter lwoffii with MIC=0.074μg⁄m and 32≤MIC μg⁄m were resistant to imipenem and meropenem, respectively.
The most prevalent species of acinetobacters in Shahid Mohammadi Hospital, Bandar Abbas, was acinetobacter baumannii. Three types of antibiotics (polymyxin B, tigecycline, and colistin) shown effective in the treatment of infections induced by these bacteria.