Tolerance to vancomycin in pneumococci: detection with a molecular marker and assessment of clinical impact

BACKGROUND: Vancomycin is often added to therapy for meningitis caused by Streptococcus pneumoniae. Tolerant bacteria without classic resistance that escape killing by multiple antibiotics have been reported sporadically. We determined the prevalence of tolerance to vancomycin in pneumococci and its effect on the outcome of meningitis. METHODS: Archival samples of 215 nasopharyngeal (NP) and 113 meningitis isolates were tested for the killing efficacy of vancomycin. Specific DNA sequence changes in a transporter locus were identified for tolerant isolates. Similar tests were conducted prospectively on 517 NP isolates from healthy children. RESULTS: In archival isolates, tolerance to vancomycin was detected in 3.7% of NP and 10.6% of invasive isolates. Patients with meningitis caused by tolerant isolates had a worse estimated 30-day survival than did patients with meningitis caused by nontolerant isolates (49% vs. 86%; P = .048); 62.5% of tolerant archival NP isolates harbored a specific sequence change for pep27 and vex2 (P = .021). Prospective analysis of 517 carriage isolates indicated that 8.1% were tolerant to vancomycin and that 82.1% of tolerant isolates harbored the specified marker gene sequences (P = .001). CONCLUSIONS: Tolerance to vancomycin exists in the population of pneumococci. Tolerant isolates are associated with meningitis of increased mortality, and these isolates can be tracked by specific marker sequences in 2 genes.     

B 超诊断前置胎盘分型的再探讨

目的 对Ｂ超诊断前置胎盘分型的改进探讨。方法 对３６例前置胎盘患者进行Ｂ超探查。观察胎盘下缘与子宫内口的关系。结果 前置胎盘的Ｂ超声像图可分四类：①胎盘中央部位于宫内口。②胎盘边缘部完全覆盖宫内口。③胎盘下缘至宫内口边缘,未覆盖宫内口。④盈盘位于子宫下截,未达到宫内口。结论 部分性前置胎盘的超声诊断分型担法不确切可予取消。将中央性前置胎盘诊断分两个亚型：中央型、边缘型。