Molecular Detection of vanA Gene among Vancomycin Resistance Clinical Isolates of Enterococcus Faecalis in Al-Najaf Hospitals, Iraq

Background: Enterococcus faecalis is one of the major causes of nosocomial infections, which can be problematic to treat because the bacteria can become resistant to most of the antimicrobial drugs used in hospitals. Antibiotic resistance to vancomycin is a significant threat. The aim of this study was to examine the antimicrobial resistance pattern in E. faecalis isolates from clinical specimens in two main hospitals in al-Najaf, Iraq, focusing on vancomycin resistance and the prevalence of the vanA gene in vancomycin-resistant E. faecalis (VREF) isolates.

Methods: This study analyzed 162 E. faecalis isolates from patient samples taken from the two largest hospitals in Najaf, Iraq. A conventional biochemical test and subsequent confirmation by an automated Vitek®2 system were used to identify all isolates. Ten antibiotics were tested for susceptibility using the disc diffusion method. The minimum inhibitory concentration (MIC) value of each E. faecalis isolates against vancomycin was determined using the E-test method. The presence of the vanA gene in VREF isolates was investigated by the polymerase chain reaction (PCR) method.

Results: Antimicrobial susceptibility patterns against 162 E. faecalis isolates collected from different clinical samples in two main hospitals in Najaf showed the highest rate of resistance to cephalosporin and aminoglycoside. The incidence of VREF was in13 (8.0%) after MIC testing. Among 13 VREF isolates, the vanA gene was detected in four isolates (31%). These isolates show susceptibility to linezolid antimicrobial.

Conclusion: The emergence of the VREF carrying the vanA gene is alarming; therefore, early detection of this gene type in E. faecalis isolates will help obtain the most appropriate antibiotics and control the spread of this resistance gene.