Presence of the esp gene in Enterococcus faecium derived from oropharyngeal microbiota of haematology patients

Antibiotic use and immunocompromised status in haematology patients have been shown to determine the constituents of commensal microbiota with highly increased resistance, including vancomycin resistant enterococci. We compared the carriage of virulence factor genes and the capacity for biofilm formation in vancomycin resistant enterococci (VRE) originating from the oropharyngeal and stool cultures of haematology patients. PCR tests were used to investigate the presence of genes encoding pathogenicity factors ( esp and hyl ) in VRE isolates. The genotype of vancomycin resistance was investigated by multiplex PCR tests for vanA and vanB genes. PFGE typing was conducted to exclude the duplicate isolates. Of 3310 pharyngeal swabs taken from inpatients at a clinic for haematology, Enterococcus species were recovered in 6.46%. All VRE investigated were identified as Enterococcus faecium and were highly vancomycin resistant. VanA genotype was confirmed in all. In the group of oropharyngeal carriers ( n  = 8 patients), 15 strains were recovered from oropharyngeal specimens and PFGE typing revealed 5 types and 3 subtypes. Identical types of VRE in the oropharynx and stool cultures were found in three patients from this group. In the group of stool carriers ( n  = 24 patients) VRE were obtained from stools only and placed in 21 macro-restriction patterns. The esp gene was more common in VRE isolated from the oropharynx than in isolates from stools ( p  = 0.014). Results were not significant when we compared the presence of hyl genes in oropharyngeal isolates with those from stool cultures ( p  = 0.66) or when we investigated the association between esp and hyl gene carriage and capability of biofilm formation in non-repeated VRE. In the present study, isolation of VRE from the oropharynx in haematology patients was associated with esp gene carriage. Further research is needed to investigate the clinical and long-term effects of this finding.