Key Laboratory of Clinical In Vitro Diagnostic Techniques of Zhejiang Province, Center of Clinical Laboratory, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China.
Department of Respiratory Diseases, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China.
BMC Infect Dis. 2018 Jul 31;18(1):358. doi: 10.1186/s12879-018-3263-x.
Klebsiella pneumoniae bloodstream infections (BSIs) occur with significant prevalence and high mortality worldwide. Antimicrobial resistance and virulence are two main factors participating in the pathogenicity of K. pneumoniae. Here we investigated the prevalence of bla and virulence factors in K. pneumoniae isolated from patients with BSIs and their association with clinical outcome.
The clinical data of 285 K. pneumoniae BSI cases diagnosed from January 2013 to December 2015 in a Chinese university hospital were retrospectively evaluated. The "string test" was performed to identify hypermucoviscous K. pneumoniae (HMKP). bla, rmpA, magA and serotype-specific genes were detected by PCR amplification. Finally, a Cox proportional hazards model was employed to determine the predictors of 14-day mortality.
Of these isolates, the prevalence of bla and rmpA were 33.3% (95/285) and 31.6% (90/285) respectively. 69 isolates (24.2%, 69/285) were HMKP. rmpA was strongly associated with HM phenotype. The KPC-producing KP and HMKP were almost non-overlapping and only three HMKP isolates harbored bla. K1 (28, 40.6%) and K2 (22, 31.9%) were the most common serotypes in HMKP. 44.9% of HMKP BSIs had origin of biliary tract infection or liver abscess. The 14-day mortality was 100% in bla/HM subgroup (3/3), followed by bla/HM (39/92, 42.4%), bla/HM (5/66, 7.6%) and bla/HM (7/124, 5.6%). The 14-day cumulative survival was significantly different between bla and bla subgroup (Log-rank p < 0.001) but almost equal between bla/HM and bla/HM subgroup (Log-rank p = 0.578) under the condition of comparable illness severity between bla/HM and bla/HM subgroup. Independent risk factors for 14-day mortality were Pitt bacteremia score (HR 1.24, CI 95% 1.13-1.36, p < 0.001), Charlson comorbidity index (HR 1.24, CI 95% 1.09-1.41, p = 0.001), septic shock (HR 2.61, CI 95% 1.28-5.35, p = 0.009) and bla (HR 2.20, CI 95% 1.06-4.54, p = 0.034).
Most of HMKP were antibiotic-susceptible and people infected received appropriate antimicrobial therapy, which may explain the favorable outcome of HMKP BSIs. The KPC-producing HMKP BSIs were scarce but life-threatening. bla was valuable in predicting 14-day mortality.
肺炎克雷伯菌血流感染（BSI）在全球范围内具有较高的发病率和死亡率。抗生素耐药性和毒力是参与肺炎克雷伯菌致病性的两个主要因素。本研究旨在调查我院 2013 年 1 月至 2015 年 12 月期间 285 例 BSI 患者分离的肺炎克雷伯菌的 bla 和毒力因子的流行情况及其与临床结局的关系。
回顾性分析我院 2013 年 1 月至 2015 年 12 月期间收治的 285 例肺炎克雷伯菌血流感染患者的临床资料。采用“string 试验”鉴定高黏液性肺炎克雷伯菌（HMKP）。采用 PCR 扩增法检测 bla 、rmpA 、magA 和血清型特异性基因。最后采用 Cox 比例风险模型确定 14 天死亡率的预测因素。
285 株分离株中 bla 和 rmpA 的检出率分别为 33.3%（95/285）和 31.6%（90/285）。69 株（24.2%，69/285）为 HMKP。rmpA 与 HM 表型密切相关。产 KPC 的肺炎克雷伯菌和 HMKP 几乎没有重叠，只有 3 株 HMKP 分离株携带 bla 。K1（28 株，40.6%）和 K2（22 株，31.9%）是 HMKP 中最常见的血清型。44.9%的 HMKP BSI 起源于胆道感染或肝脓肿。bla/HM 亚组的 14 天死亡率为 100%（3/3），其次是 bla/HM （39/92，42.4%）、bla/HM （5/66，7.6%）和 bla/HM （7/124，5.6%）。在 bla/HM 和 bla/HM 亚组之间疾病严重程度相匹配的情况下，bla 和 bla 亚组之间的 14 天累积生存率差异有统计学意义（Log-rank p<0.001），但 bla/HM 和 bla/HM 亚组之间的差异无统计学意义（Log-rank p=0.578）。14 天死亡率的独立危险因素为 Pitt 菌血症评分（HR 1.24，95%CI 1.13-1.36，p<0.001）、Charlson 合并症指数（HR 1.24，95%CI 1.09-1.41，p=0.001）、感染性休克（HR 2.61，95%CI 1.28-5.35，p=0.009）和 bla （HR 2.20，95%CI 1.06-4.54，p=0.034）。
大多数 HMKP 对抗生素敏感，感染患者接受了适当的抗菌治疗，这可能解释了 HMKP BSI 良好的临床结局。产 KPC 的 HMKP BSI 较为罕见，但危及生命。bla 有助于预测 14 天死亡率。
