Molecular Detection of Van A and bap Genes in Staphylococcus Species Isolated from Hemodialysis Patients with Blood Stream Infections

Abstract

Background:Bloodstream infections (BSIs) are a frequent consequence of hemodialysis caused by bacterial pathogens associated with Staphylococcus spp. especially Staphylococcus aureus followed by coagulase-negative Staphylococci, which can produce biofilms, and also show its ability to increase resistance to vancomycin. Objectives:Estimate the percentage of Staphylococcus spp. associated with BSIs in hemodialysis (HD) patients. Study the antibiogram pattern of isolates and detection of the resistance gene van A and virulence bap gene. Materials and Methods:A total of 120 blood samples, 60 from patients on hemodialysis and 60 patients suspected of bacteremia, were collected. The isolation of bacteria was performed by blood samples inoculated in BacT/ALERT bottles and then subcultured on blood agar. Identification and antibiotic sensitivity testing detection were performed by the Vitek-2 system; then a conventional polymerase chain reaction for van A and bap genes was done. Results:The percentage of S. aureus was 64.7% within the group of HD patients followed by Staphylococcus lentus 11.8%, Staphylococcus hemolyticus 8.8%, and Staphylococcus hominis 5.9%, whereas in non-HD patients’ group, S. aureus was 50.0% and S. lentus 25.0%. All Staphylococcus spp. was completely resistant to vancomycin in HD and non-HD patients. The percentage of van A gene was 91.2% and 83.3% within HD and non-HD patients, respectively. The percentage of bap gene was 55.9% and 58.3% within HD and non-HD patients, respectively. Conclusion:Staphylococcus aureus is the most common bacterium that causes bacteremia in dialysis patients, while other types contribute with a lower frequency.

Keywords

• bacteremia
• bap gene
• van a