Antibiotic-resistance Patterns and Frequency of TEM and CTX Type Extended-spectrum β-lactamases in Acinetobacter Clinical Isolates

Background and Acinetobacter has emerged as a significant opportunistic pathogen responsible for nosocomial infections. Treatment of infections due to this organism is becoming a serious clinical concern and this bacterium is frequently resistant to multiple classes of antibiotics such as family of β-lactam drugs. β-lactamases enzyme represent the main mechanism of bacterial resistance to β-lactam antibiotics. This study was conducted to determine the prevalence of TEM-1and CTX β-lactamases in acinetobacter isolates collected from two teaching hospitals in Sari (north of Iran). This study included 100 acinetobacter isolates that were collected from various clinical specimens. Susceptibility of isolates toward the antibiotics was determined by standard disk diffusion method. ESBL production was determined by the combination disk method. Using disks containing ceftazidime and cefotaxime alone and in combination with Clavulanic acid and TEM and CTX types of ESBL producing genes was detected by PCR test. Among all acinetobacter isolates, the highest resistance was seen for cefotaxime (100%) and ceftazidim (100%), whereas the highest susceptibility was observed for colistin (65%). Combined Disc Test showed that 24% of isolates were ESBL positive and among them 79.1% and 31.5% were positive for blaTEM and blaCTX genes. TEM-1and CTX β-lactamases in acinetobacter isolates According to this study the drug-resistance pattern in acinetobacter isolates was seen in 24% of TEM and CTX which were β lactamas producers. Thus, other mechanisms such as secretory pump, purines, and biofilm formation could have a role in drug resistance.