McCaskill Michelle L, Mason Edward O, Kaplan Sheldon L, Hammerman Wendy, Lamberth Linda B, Hultén Kristina G
Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA.
Pediatr Infect Dis J. 2007 Dec;26(12):1122-7. doi: 10.1097/INF.0b013e31814536e0.
Methicillin-resistant Staphylococcus aureus (MRSA) USA300 is a predominant cause of community-acquired (CA) infection in the United States. We compared clinical characteristics of children with USA300 versus non-USA300 CA-methicillin-susceptible S. aureus (CA-MSSA) invasive infections at Texas Children's Hospital (TCH).
Medical records were reviewed from children with invasive CA-MSSA infections at TCH between August 1, 2001 and September 30, 2006. Isolates were characterized by pulsed-field gel electrophoresis and polymerase chain reaction for Panton-Valentine leukocidin genes (pvl).
Invasive CA-MSSA infections increased from 14 in year 1 to 36 in year 5 (5-year total = 122 patients). Among the CA-MSSA isolates available for typing in the 5-year period, USA300 MSSA strains increased from 14% (2 of 14) to 35% (11 of 31) (P = 0.03). USA300 MSSA strains were more likely than non-USA300 MSSA strains to be nonsusceptible to erythromycin [66% (19 of 29) versus 28% (25 of 88); P < 0.01]. Osteomyelitis cases increased from 43% (6 of 14) in year 1 to 67% (24 of 36) in year 5. The majority of pvl(+) MSSA isolates were USA300 (71% (25 of 35); only 5% (4 of 82) of pvl(-) MSSA isolates were USA300. Patients with osteomyelitis caused by pvl isolates had significantly higher mean values for erythrocyte sedimentation rate at admission (P = 0.005) and erythrocyte sedimentation rate maximum value (P = 0.002), maximum C-reactive protein (P = 0.04), and absolute neutrophil count at presentation (P = 0.04) compared with patients whose isolates were pvl(-).
USA300 accounted for a growing proportion of CA-MSSA isolates among children and was associated with increased numbers of invasive CA-MSSA infections at TCH, especially osteomyelitis. Associations were found in CA-MSSA osteomyelitis between pvl and increased concentrations of systemic inflammatory markers in patients.
耐甲氧西林金黄色葡萄球菌（MRSA）USA300是美国社区获得性（CA）感染的主要病因。我们比较了德克萨斯儿童医院（TCH）中感染USA300与非USA300的社区获得性甲氧西林敏感金黄色葡萄球菌（CA-MSSA）侵袭性感染患儿的临床特征。
回顾了2001年8月1日至2006年9月30日期间在TCH发生侵袭性CA-MSSA感染患儿的病历。通过脉冲场凝胶电泳和针对杀白细胞素基因（pvl）的聚合酶链反应对分离株进行特征分析。
侵袭性CA-MSSA感染从第1年的14例增加到第5年的36例（5年总计 = 122例患者）。在5年期间可用于分型的CA-MSSA分离株中，USA300 MSSA菌株从14%（14例中的2例）增加到35%（31例中的11例）（P = 0.03）。USA300 MSSA菌株比非USA300 MSSA菌株更易对红霉素不敏感[66%（29例中的19例）对28%（88例中的25例）；P < 0.01]。骨髓炎病例从第1年的43%（14例中的6例）增加到第5年的67%（36例中的24例）。大多数pvl(+) MSSA分离株为USA300（71%（35例中的25例）；pvl(-) MSSA分离株中只有5%（82例中的4例）为USA300。与分离株为pvl(-)的患者相比，由pvl分离株引起骨髓炎的患者入院时红细胞沉降率平均值（P = 0.005）、红细胞沉降率最大值（P = 0.002）、最大C反应蛋白（P = 0.04）及就诊时绝对中性粒细胞计数（P = 0.04）显著更高。
USA300在儿童CA-MSSA分离株中所占比例越来越大，并且与TCH侵袭性CA-MSSA感染数量增加相关，尤其是骨髓炎。在CA-MSSA骨髓炎中发现pvl与患者全身炎症标志物浓度升高有关。
