Enterococci normally inhabit the intestinal tract of humans and are also a potential pathogen in causing nosocomial infections. The increase in antibiotic resistance and transfer of antibiotic resistance gene to Staphylococcus aureus (S. aureus) due to co-colonization has increased its importance in research. Yameen, et al. (2013) sought to evaluate local epidemiology of nasal and rectal colonization with Enterococcus faecalis (E. faecalis) and Enterococcus faecium (E. faecium) in patients of the Pediatrics Intensive Care Unit (PICU) and correlation with clinical and socioeconomic factors.
The nasal and perirectal swab samples were collected from 110 patients admitted in PICUs of three tertiary care hospitals of Rawalpindi Medical College, Pakistan. The identification of enterococci was done by biochemical tests and by PCR for ddl, vanA and vanB genes. Antibiotic susceptibility testing was performed by disc diffusion and MICs were determined for vancomycin, tetracycline, ciprofloxacin and oxacillin only.
Out of 220 nasal and perirectal samples, nine vancomycin-resistant enterococci (VRE) and 76 vancomycin-susceptible enterococci (VSE), consisting of 40 E. faecalis and 45 E. faecium were isolated. PCR successfully identified both species with ddl primers and VRE with vanA primer. With disc diffusion method, all isolates were resistant to most of the antibiotics tested except linezolid, quinupristin/dalfopristin, teicoplanin and vancomycin. VRE showed resistance to teicoplanin and vancomycin both and none was resistant to linezolid and quinupristin/dalfopristin. Generally, E. faecium isolates were more resistant than E. faecalis. MICs of vancomycin for nasal and perirectal VRE were 512 mg/L and 64 to 512 mg/L respectively. VRE were more in patients with prolonged hospitalization, from urban localities and those having pneumonia.
The researchers conclude that there is high colonization and antibiotic resistance in enterococcal isolates from nasal and perirectal area. Nasal colonization by enterococci in PICU is more alarming as VRE may cause infection and can transfer this resistance gene to other microorganisms like S. aureus. Their research was published in BMC Infectious Diseases.
Reference: Yameen MA, et al. Nasal and perirectal colonization of vancomycin sensitive and resistant enterococci in patients of paediatrics ICU (PICU) of tertiary health care facilities. BMC Infectious Diseases 2013, 13:156 doi:10.1186/1471-2334-13-156