Investigation on hemolysis, resistance and homology of Staphylococcus cohnii urealyticum

Objective To investigate the characteristics of hemolysis, resistance and homology of Staphylococcus cohnii urealyticum. Methods A retrospective study was carried out on thirteen clinical strains of Staphylococcus cohnii urealyticum. They were re-identified by MALDI-TOF MS. Their colony and hemolytic characteristics on blood agar plates were observed. The co-hemolysis between Staphylococcus cohnii urealyticum and Staphylococcus aureus was demonstrated. The hemolysin genes and drug resistance genes were detected by PCR. Pulsed field gel electrophoresis and mass spectrometry were used to analyze the homology of strains. The susceptibility of strains to antimicrobial agents was detected by agar dilution. Results The confirmed 13 strains of Staphylococcus cohnii urealyticum showed various levels of hemolysis and had enhanced synergistic hemolysis with Staphylococcus aureus. All strains were susceptible to vancomycin and tigecycline. There were 12 strains which carried mecA gene, 7 strains carried cfr gene, 7 strains carried ermC gene. The 13 strains were divided into 3 groups by MALDI-TOF MS, and 6 types by pulsed field gel electrophoresis. Conclusions Clinical strains of Staphylococcus cohnii urealyticum demonstrated various levels of hemolysis which could be enhanced by Staphylococcus aureus. Although they carried different drug resistance genes, they were all susceptible to vancomycin and tigecycline. Key words: Staphylococcus; Drug resistance, bacterial; Sequence homology