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Identification of aminoglycoside resistance genes by Triplex PCR in Enterococcus spp. isolated from ICUs
Reza Mirnejad1, Nikta Sajjadi2, Sara Masoumi Zavaryani3
1Molecular Biology Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran.
Abstract:
Early detection of antibiotic-resistant enterococci is an important part of patient treatment. Therefore, the aim of the present study was to evaluate the resistance patterns and simultaneously identify and characterise the resistance genes in Enterococcus spp. using a triplex polymerase chain reaction (PCR) method. In all, 150 consecutive Enterococcus spp were collected from several hospitals in Tehran (Iran) from January to December 2015. The Enterococcus species were identified by standard phenotypic/biochemical tests and PCR. The antimicrobial resistance patterns were determined using a disk diffusion method. The triplex PCR method was designed to identify gentamicin and other aminoglycoside resistance genes. Among the 150 Enterococcus specimens, 87 cases (58%) were Enterococcus faecalis, and 63 cases (42%) were Enterococcus faecium. The highest frequency of resistance was observed for tetracycline while the lowest was found for vancomycin. Among the identified samples, 56.9% contained the aac(6')-Ie-aph(2'')-Ia gene, 22.2% contained the aph(3')-IIIa gene, and 38.8% contained the ant(4')-?a gene. Eight percent of the isolates contained the three aminoglycoside resistance genes. Data analysis showed that there was a significant correlation between the phenotypic gentamicin resistance and the presence of the aminoglycoside resistance genes (18.9%, p <0.05), while the correlation between the phenotypic streptomycin resistance and the corresponding genes was not significant (2.8%, p ≥0.5). Nearly half of the identified Enterococcus strains had increased aminoglycoside resistance. The direct correlation between resistance genes, such as the aminoglycoside resistance factor, and phenotypic resistance was not significant (p > 0.05).
Insights
Early detection of antibiotic-resistant enterococci is crucial for patient care. This study identified resistance genes in Enterococcus species using triplex PCR, finding high rates of aminoglycoside resistance and specific resistance genes.
Area of Science:
- Microbiology
- Molecular Biology
- Clinical Research
Background:
- Antibiotic resistance in Enterococcus species poses a significant threat to patient treatment.
- Early identification of resistance mechanisms is essential for effective patient management.
Purpose of the Study:
- To evaluate antimicrobial resistance patterns in Enterococcus species.
- To identify and characterize specific resistance genes using a triplex polymerase chain reaction (PCR) method.
Main Methods:
- Collected 150 Enterococcus specimens from Tehran hospitals (2015).
- Identified species using phenotypic/biochemical tests and PCR.
- Determined antimicrobial resistance patterns via disk diffusion.
- Employed triplex PCR to detect gentamicin and aminoglycoside resistance genes.
Main Results:
- Enterococcus faecalis (58%) and Enterococcus faecium (42%) were identified.
- Highest resistance observed for tetracycline; lowest for vancomycin.
- Prevalence of resistance genes: aac(6')-Ie-aph(2'')-Ia (56.9%), aph(3')-IIIa (22.2%), ant(4')-?a (38.8%).
- Significant correlation found between phenotypic gentamicin resistance and specific aminoglycoside resistance genes (18.9%, p <0.05).
Conclusions:
- Nearly half of Enterococcus strains exhibited increased aminoglycoside resistance.
- While specific resistance genes were prevalent, direct correlation with phenotypic resistance was not always significant.
- Triplex PCR is effective for identifying resistance genes in Enterococcus species.
