Detection and Distribution of various HLAR Gene in Enterococcus faecalis and Enterococcus faecium by Multiplex-PCR

Background: In recent years, three new aminoglycoside resistance genes such as aph (3ʹ)-IIIa and ant (4ʹ)-Ia, that encode for the APH (3ʹ) and ANT (4ʹ) have also been identified. The aim of this study was to come up with a multiplex-PCR procedure for detection of aac(6ʹ)-Ie–aph(2ʹʹ)-Ia, aph(3ʹ)-IIIa, ant(4ʹ)-Ia genes in the Enterococcus spp. clinical isolates. Material and Method: 100 samples were isolated from various specimens, from various hospitals in Tehran, Iran. The grown colonies were identified by standard biochemical and disc diffusion tests. Multiplex-PCR for aac (6’)-Ie -aph(2’’)-Ia , aph(3ʹ)-IIIa, ant(4ʹ)-Ia genes amplification were performed in order to confirm bacterial colonies as Enterococcus spp. Results: Eighty four (84%) Enterococcus spp. isolates were collected from the 100 specimens. The highest and lowest isolates were related to urine (48%) and sputum (2%). Antibiotic susceptibility test results showed that the highest and lowest resistance was related to tetracycline and nitrofurantoin, respectively. Multiplex PCR results revealed that aac (6ʹ)-Ie-aph (2ʹʹ)-Ia, ant (4ʹ)-Ia and aph (3ʹ)-IIIa genes were present in 6% of the isolated bacteria from the urine, 2% from the wound and 1% from the pleural samples. the aac (6ʹ)-Ie-aph (2ʹʹ)-Ia and aph (3ʹ)-IIIa genes were present in 25% of the isolated strains from the urine, 3% from the wound and 2% from the plural specimens. Nine percent of the strains were isolated from the urine, 3% from the wound and 1% from the plural were positive for aac (6ʹ)-Ie-aph (2ʹʹ)-Ia and ant (4ʹ)-Ia genes. Conclusion: we had observed enterococci isolates with phenotypic resistance to HLAR and demonstrated aac(6′)-Ie-aph(2′′)-Ia and aph(3′)-IIIa genes more frequently occurring than other genes. A collection of AMEs are accountable for HLAR status among Enterococcus species. The aac (6ʹ)-Ie-aph (2ʹʹ)-Ia gene was detected more frequently than the other genes.