课件：MRSA的现状和挑战.ppt

* * * The infectious organisms that are responsible for nosocomial pneumonia are generally different from pathogens associated with community-acquired respiratory infections. Nosocomial pneumonia infections can be caused by a wide variety of pathogens, though the most common are Staphylococcus aureus and the enteric gram-negative bacteria (such as Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa). However, it has been estimated that up to 50% of infections in mechanically ventilated patients are polymicrobial. This can make choosing targeted antimicrobial therapy difficult even after the pathogens are identified. Thus, broad spectrum antimicrobials and combination antimicrobial therapy are typically used to treat these infections empirically. * * * * Treatment options for MRSA Infections Key Point: Vancomycin remains the gold standard for MRSA treatment All treatments for MRSA have limitations Supplemental Information: Exposure to vancomycin may affect susceptibility to daptomycin Cell wall changes observed in glycopeptide-intermediate S aureus strains may interfere with daptomycin activity by decreasing the ability of daptomycin to access relevant binding regions on the bacterial cell membrane Reference: Sakoulas G, et al. Antimirob Agents Chemother. 2006;50:1581-1585. * * * * Implications of Decreasing Vancomycin Susceptibility Key Points: MRSA strains with reduced susceptibility to vancomycin have emerged Increasing vancomycin MICs for S aureus Potential for treatment failure may increase as the MIC increases, even within the defined “susceptible” MIC range Supplemental Information: Wang et al reported the results of susceptibility tests routinely performed for isolates submitted to the UCLA Clinical Microbiology Laboratory between January 2000 and December 2004 Sakoulas et al performed a multicenter prospective surveillance study of patients with MRSA bacteremia (n = 87) between July 1998 and November 2001. A subset of 30 isolates from 30