血培养凝固酶阴性葡萄球菌阳性的临床意义

目的 :评价血培养中凝固酶阴性葡萄球菌 (CNS)阳性的临床意义。方法 :对本院 1995～ 1999年血中分离到CNS的70例住院患者进行回顾性分析 ,判定是菌血症还是血样本污染。结果 :70例患者中 37例 (5 2 .9% )为菌血症 ,其入侵部位 15例 (4 0 .5 % )为静脉插管及人工装置 ,8例 (2 1.6 % )为术后伤口感染 ,4例为呼吸道 ,4例为脐带 ,1例为眼部 ,5例不明。 37例菌血症主要发生于重症监护病房、新生儿病房、外科病房和血液科病房。入院 48h内检出的CNS中 ,2 4株 (39.3% )为污染菌 ,入院 48h以后检出的CNS ,均为污染菌 (9株 ) ;污染菌的检出时间显著长于病原菌 (36 .2h/2 1.9h ,P =0 .0 1)。病原菌与污染菌对青霉素、苯唑西林、庆大霉素、环丙沙星、万古霉素的敏感性差异无显著性 (P >0 .2 5 )。在 15例由静脉插管及人工装置引起的菌血症中 ,10例经拔除导管后 ,菌血症得到控制 ;另 5例还同时使用了万古霉素 ,菌血症才得以控制。结论 :CNS血培养阳性时污染率较高 ,需综合临床和实验室的资料判定其临床意义 ,避免不必要地使用万古霉素等抗微生物药物

Clinical significance of coagulase-negative staphylococci in blood culture

Objective:To evaluate the clinical significance of coagulase negative staphylococci(CNS) in blood culture. Methods: A retrospective analysis of coagulase negative staphylococci in blood culture from 70 hospitalized patients in Peking Union Medical College Hospital from 1995 to 1999 was done. Strains of true bacteremia pathogens or contaminants were identified. Results: 37 of 70(52.9%) strains were from patients with CNS bacteremia, 15 strains(40.5%) were from inserted catheter of prothetic medical devices, 8(21.6%) from postoperative wounds, 4 from respiratory tract, 4 from umbilicus, 1 from eye and 4 strains of unknown origin. Most of 37 bactereima cases were in intensive care units, neonatal ward, surgical wards and hematological disease ward, 18 of 46(39.3%) strains were isolated within 48 hours of admission, 6 of 15(40%) strains isolated within 25 to 48 hours of admission and all 9 strains isolated after 48 hours of adminssion were contaminants. The mean growth time of contaminants was significantly longer than that of the true pathogens(36.2h/21.9h, P=0.01). No significant difference were found between the susceptibility of contaminants and pathogens(P>0.25). 10 of 15 true bacteremia cases due to catheters and prothetic medical devices cured after the removal of catheters. The other 5 cases cured by removing catheters in combinationwith with vaucomycin. Conclusions: The incidence of CNS contamination in blood culture was relatively high. It is important to identify true bacetermia or contamination by carefully review all the clinical, epidemiological and laboratory data so ao to reduce the abuse of antimicrobials, especially vancomycin.