Staphylococcus Heterogeneously Resistant to Vancomycin in China and Antimicrobial Activities of Imipenem and Vancomycin in Combination against It

Of 115 methicillin-resistant Staphylococcus strains collected from sputum specimens, 34 strains reduced susceptibility to vancomycin, 9 of which emerged as heterogeneous vancomycin-resistant strains (hetero-VRS), with various degrees of vancomycin resistance at a frequency of 10(−6) or higher. Seventy-six percent (19 of 25) of non-hetero-VRS and 100% (9 of 9) of hetero-VRS were susceptible to synergistic treatment with vancomycin and imipenem. Clinical clearance between 9 hetero-VRS and 25 non-hetero-VRS had an obvious statistical significance (P = 0.001). The hetero-VRS may play an important role in vancomycin therapy failure.