Ruotsalainen Eeva, Kardén-Lilja Minna, Kuusela Pentti, Vuopio-Varkila Jaana, Virolainen-Julkunen Anni, Sarna Seppo, Valtonen Ville, Järvinen Asko
Division of Infectious Diseases, Department of Medicine, Helsinki University Central Hospital, Helsinki, Finland.
J Infect. 2008 Apr;56(4):249-56. doi: 10.1016/j.jinf.2008.01.009. Epub 2008 Mar 7.
Endocarditis has been associated with lower mortality and fewer complications among injection drug users (IDUs) than nonaddicts in Staphylococcus aureus bacteraemia (SAB). The better prognosis of IDUs has not been clarified but it has generally been explained by younger age and other host factors. In this study, bacterial strains, their virulence factors, and host immune responses were compared among IDUs and nonaddicts with SAB, including those with and without endocarditis.
A total of 430 consecutive adult patients with methicillin-sensitive SAB were followed prospectively for 3 months. All 44 IDUs were included, and 44 nonaddicts as controls for them. According to the modified Duke criteria, 20 patients in both groups had endocarditis. For each addict without endocarditis, an age and sex matched nonaddict was selected as a control. S. aureus isolates were assigned a genotype by PFGE, Panton-Valentine leukocidin (PVL), staphylokinase (SAK), protease, and haemolysin production. Acute and convalescent sera were tested for antibodies to alpha-haemolysin (ASTA) and teichoic acid (TAA).
There were no differences between IDUs and nonaddicts with SAB in the proportion of patients with a deep infection (98% vs 86%, P=0.06) or a thromboembolic complication (30% vs 14%, P=0.12). Endocarditis among IDUs was not associated with any specific strains, and only the FIN-4 strain was observed more often in IDUs than in nonaddicts (21% vs 5%, P=0.03). The majority of isolates (98%) were PVL negative, and there were no differences in the numbers of SAK, protease and haemolysin production among strains between IDUs and nonaddicts. However, haemolytic properties were found more frequently in strains from IDUs without endocarditis than those with endocarditis (88% vs 47%, P=0.007). IDUs displayed more often elevated TAA titers than nonaddicts, especially in endocarditis at acute phase (33% vs 5%, P=0.04) and at convalescent phase (50% vs 10%, P=0.01). The ASTA titer was more frequently initially positive among IDUs without endocarditis than with endocarditis (44% vs 6%, P=0.01).
Characterization of the bacterial strains and their virulence factors, and host immune responses did not reveal significant differences between IDUs and nonaddicts with similar clinical picture of SAB. Serological tests were not helpful in identifying patients with endocarditis.
在金黄色葡萄球菌菌血症（SAB）中，与非成瘾者相比，注射吸毒者（IDU）患心内膜炎的死亡率更低，并发症更少。IDU预后较好的原因尚未明确，但一般认为是年龄较轻和其他宿主因素所致。在本研究中，对患有SAB的IDU和非成瘾者（包括有心内膜炎和无心内膜炎者）的细菌菌株、其毒力因子和宿主免疫反应进行了比较。
对430例连续的对甲氧西林敏感的SAB成年患者进行了为期3个月的前瞻性随访。纳入了所有44例IDU，并选取44例非成瘾者作为对照。根据改良的杜克标准，两组各有20例患者患有心内膜炎。对于每例无心内膜炎的成瘾者，选择一名年龄和性别匹配的非成瘾者作为对照。通过脉冲场凝胶电泳（PFGE）、杀白细胞素（PVL）、葡萄球菌激酶（SAK）、蛋白酶和溶血素的产生对金黄色葡萄球菌分离株进行基因分型。检测急性期和恢复期血清中抗α溶血素（ASTA）和磷壁酸（TAA）的抗体。
患有SAB的IDU和非成瘾者在深部感染患者比例（98%对86%，P = 0.06）或血栓栓塞并发症比例（30%对14%，P = 0.12）方面没有差异。IDU的心内膜炎与任何特定菌株均无关联，仅FIN - 4菌株在IDU中比在非成瘾者中更常见（21%对5%，P = 0.03）。大多数分离株（98%）为PVL阴性，IDU和非成瘾者之间菌株产生SAK、蛋白酶和溶血素的数量没有差异。然而，无心内膜炎的IDU菌株的溶血特性比有心内膜炎的菌株更常见（88%对47%，P = 0.007）。IDU的TAA滴度比非成瘾者更常升高，尤其是在急性期的心内膜炎（33%对5%，P = 0.04）和恢复期（50%对10%，P = 0.01）。无心内膜炎的IDU中ASTA滴度最初呈阳性的情况比有心内膜炎的IDU更常见（44%对6%，P = 0.01）。
细菌菌株及其毒力因子以及宿主免疫反应的特征表明，患有类似SAB临床表现的IDU和非成瘾者之间没有显著差异。血清学检测对识别心内膜炎患者没有帮助。
