Rice Louis B
Department of Medicine, Case Western Reserve University, Cleveland, Ohio, USA.
Am J Med. 2006 Jun;119(6 Suppl 1):S11-9; discussion S62-70. doi: 10.1016/j.amjmed.2006.03.012.
Gram-positive bacteria are common causes of bloodstream and other infections in hospitalized patients in the United States, and the percentage of nosocomial bloodstream infections caused by antibiotic-resistant gram-positive bacteria is increasing. Methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) are of particular concern. In the United States, approximately 60% of staphylococcal infections in the intensive care unit are now caused by MRSA, and percentages continue to rise. Outbreaks of hospital-acquired MRSA (HA-MRSA) are typically the result of clonal spread by MRSA being transferred from patient to patient, frequently using healthcare personnel as intermediaries. HA-MRSA strains are generally multidrug resistant. Vancomycin is the standard treatment for serious MRSA infections, but a few cases of vancomycin-resistant S aureus (VRSA) have recently emerged in the United States. Community-acquired MRSA (CA-MRSA) is also increasing. Soft tissue infections are the most frequent presentations of CA-MRSA, but life-threatening invasive infections occur as well, including necrotizing pneumonia. The mechanisms of methicillin resistance are the same for CA-MRSA and HA-MRSA, but susceptibilities to non-beta-lactam antibiotics often differ. CA-MRSA exhibits broader antibiotic susceptibility than does HA-MRSA. The proportion of enterococci resistant to vancomycin continues to rise in the hospital setting, with the overwhelming majority of infections due to Enterococcus faecium. Clonal spread of VRE has been documented, but polyclonal outbreaks associated with antimicrobial use are also common. The relations between antibiotic use and VRE colonization are complex and related to the antienterococcal activity, biliary excretion, and antianaerobic activity of the antibiotic. Recent results show a decline in invasive pneumococcal disease (IPD) since the introduction of 7-valent pneumococcal conjugate vaccine, and suggest that, where available, vaccines may be useful in the battle to slow the spread of resistant gram-positive cocci.
在美国，革兰氏阳性菌是住院患者血流感染和其他感染的常见病因，并且由耐抗生素革兰氏阳性菌引起的医院血流感染比例正在上升。耐甲氧西林金黄色葡萄球菌（MRSA）和耐万古霉素肠球菌（VRE）尤其令人担忧。在美国，重症监护病房中约60%的葡萄球菌感染现在由MRSA引起，且这一比例持续上升。医院获得性MRSA（HA-MRSA）的暴发通常是由于MRSA通过患者之间的传播进行克隆扩散，医护人员常常充当传播媒介。HA-MRSA菌株通常具有多重耐药性。万古霉素是严重MRSA感染的标准治疗药物，但美国最近出现了几例耐万古霉素金黄色葡萄球菌（VRSA）病例。社区获得性MRSA（CA-MRSA）也在增加。软组织感染是CA-MRSA最常见的表现形式，但也会出现危及生命的侵袭性感染，包括坏死性肺炎。CA-MRSA和HA-MRSA对甲氧西林耐药的机制相同，但对非β-内酰胺类抗生素的敏感性往往不同。CA-MRSA比HA-MRSA表现出更广泛的抗生素敏感性。在医院环境中，对万古霉素耐药的肠球菌比例持续上升，绝大多数感染是由粪肠球菌引起的。VRE的克隆传播已有记录，但与抗菌药物使用相关的多克隆暴发也很常见。抗生素使用与VRE定植之间的关系很复杂，与抗生素的抗肠球菌活性、胆汁排泄和抗厌氧活性有关。最近的结果显示，自引入7价肺炎球菌结合疫苗以来，侵袭性肺炎球菌疾病（IPD）有所下降，这表明在可行的情况下，疫苗可能有助于减缓耐药革兰氏阳性球菌的传播。
