Abstract
Burkholderia pseudomallei are a causative agent of melioidosis and ceftazidime is the drug of choice for treatment. However, the motility rate is high in endemic areas. This study aimed to investigate an incident of the blaPenA and blaOXA mutation and tendency of β-lactam antibiotics in B. pseudomallei from patients admitted to hospitals in lower North-East Thailand. A total of 1,340 isolates of patients with B. pseudomallei admitted to Sappasitthiprasong Hospital, Sisaket Hospital, and Amnatcharoen Hospital between January 2013 and February 2015 were determined for antimicrobial susceptibility by standard disk diffusion and minimum inhibitory concentration (MIC). The conventional polymerase chain reaction (PCR) was used for the detection of blaPenA and blaOXA in β-lactamase genes with the specific primers. Almost all of the clinical isolates of B. pseudomallei were susceptible to ceftazidime, piperacillin, cotrimoxazole, cipofloxacin, and imipenem by the standard disk diffusion test. Cefatzidime MIC was ≤1-≥32 μg/ml and imipenem MIC was ≤0.5-≥8 μg/ml. MIC50 and MIC90 of ceftazidime were 2 μg/ml and 4 μg/ml respectively, and MIC50 and MIC90 of imipenem were ≤0.5 μg/ml and 1 μg/ml respectively. The conventional PCR followed by gel electrophoresis revealed that only Class D beta-lactamase gene or oxa was detected in all DNA samples isolated from B. pseudomallei. DNA sequencing followed by amino acid analysis and comparison by the bioinformatic approach found that all translated amino acid sequences showed 100% identity to those reported in the National Center for Biotechnology Information (NCBI) database. This result demonstrated that there were no any mutations in oxa gene in B. pseudomallei. PenA gene was not detected in all DNA samples. However, the penA gene with the length of 300-500 bp was detected from the beginning of this study. It is suggested that this amplified product be sent for sequencing to confirm that it is penA.
