Immunization with PhtD truncated fragments reduces nasopharyngeal colonization by Streptococcus pneumoniae

Despite the undeniable success of polysaccharide vaccines against Streptococcus pneumoniae infections, there is a consensus on the scientific field that this approach should be revised in order to overpass the problems related with these formulations, such as serotype replacement and high production costs. The study of conserved pneumococcal proteins or its truncated fragments has emerged as a serotype independent alternative. In this work, we have characterized the immune response elicited by systemic immunization of mice with the Histidine triad protein D (PhtD) and its’ amino and carboxyl terminal fragments. The proteins were shown to be immunogenic and protective against pneumococcal colonization, with increased IL-17 production, and induction of antibodies able to limit pneumococcal adhesion to human respiratory cells. Antiserum against PhtD_Nter, but not C_ter or PhtD, promoted an increase in bacterial phagocytosis in vitro. Interestingly, antibodies against the PhtD_Nter displayed cross-reactivity with two other pneumococcal proteins, PspA and PspC, due to sequence similarities in the proline rich region of the molecules. On a whole, our results support the inclusion of PhtD, and more specifically, its N-terminal fragment, in a multicomponent serotype independent vaccine.     

孕妇B族链球菌定植及其早产儿感染状况的研究

目的探讨孕妇B族溶血性链球菌（GBS）定植及其分娩早产儿的GBS感染状况,评估早产儿GBS定植的危险因素。方法采用前瞻性队列研究方法,纳入2017年1月至2018年1月分娩的859例早产孕妇作为研究对象。入院时采集孕妇阴道下段1/3和直肠拭子行GBS培养,其中515例行实时PCR GBS DNA检测。采集所纳入孕妇分娩的早产儿的口咽分泌物、胃液或血液进行GBS培养。取孕妇外周血及其分娩的早产儿脐血测定抗GBS荚膜多糖抗体水平。调查早产儿GBS感染情况和影响定植的围产因素。结果 859例孕妇阴道、直肠GBS培养阳性率为14.8%（127/859）。515例GBS DNA检测的阳性率为15.1%（78/515）。859例孕妇共分娩活产早产儿976例,其中43例（4.4%）GBS培养阳性;4例发生早发型GBS疾病,其中2例肺炎,2例早发型GBS败血症。127例GBS阳性孕妇分娩的127例早产儿中,34~<37周早产儿组GBS阳性率明显低于<34周早产儿组（P=0.013）,抗GBS荚膜多糖抗体水平明显高于<34周早产儿组（P=0.001）。多因素logistic回归分析显示胎膜早破>18 h和绒毛膜羊膜炎是早产儿GBS定植的独立危险因素（分别OR=6.556、6.160,均P < 0.05）。结论早产儿GBS阳性率及抗GBS荚膜多糖抗体水平与胎龄相关。胎膜早破>18 h和绒毛膜羊膜炎可增加早产儿GBS定植的风险。     

Effect of prior vaccination on carriage rates of Streptococcus pneumoniae in older adults: A longitudinal surveillance study

IntroductionPneumococcus is a commensal of the upper respiratory tract and colonization is common in young children. Carriage studies have provided insights on vaccine effects in children and may also be useful for assessing vaccines in adults. However, culture based prevalence studies in older adults describe low colonization rates. Therefore, we assessed cumulative incidence of pneumococcal colonization in older adults using polymerase chain reaction (PCR) targeting the lytA gene and risk factors for carriage.Methods100 community-dwelling adults ≥65 years were enrolled the winter of 2015 and followed biweekly for 12 months. Medical, vaccination and illness history as well as nasopharyngeal (NP) and oropharyngeal (OP) samples were collected. Combined OP and NP were incubated in enrichment broth and screened using real-time lytA PCR. Samples from new colonization events (lytA PCR+) were cultured on gentamicin blood agar plates. Isolates identified by colony morphology as S. pneumoniae were serotyped using a multiplex combined immunoassay-PCR platform which classifies 96 serotypes. Cumulative incidence of pneumococcal carriage was calculated and risk factors for carriage assessed.ResultsThe cumulative incidence of colonization was 41% by PCR and 14% by culture. Monthly prevalence ranged from 0 to 17% by PCR and 1 to 4% by culture with peaks in the spring and fall. Demographics were similar between colonized and never colonized subjects although colonized were younger (72.4 vs. 75.0 years, P = 0.06). Vaccination with any pneumococcal vaccine before or during study period was associated with decreased risk of becoming colonized (p < 0.001) as was vaccination with either the 13-valent conjugated pneumococcal vaccine (PCV13) or 23-valent polysaccharide vaccine (PPSV23) (p < 0.001).ConclusionPneumococcal colonization in older adults as detected by lytA PCR is frequent and pneumococcal vaccination appears to be associated with decreased risk of carriage. Further study is needed to understand the biological significance of molecular detection of pneumococcus in adults.     

How should microbiology laboratories interpret cultures of the sonicate of closed needleless connectors?

IntroductionOur objective was to determine whether there is a cut-off in the needleless connectors’ (NCs) cultures that when combined with skin cultures it was as efficient as conventional superficial cultures to rule-out catheter colonization (CC) and catheter-related bloodstream infection (CRBSI).MethodsDuring 10 months, we collected samples and then we analyzed the validity values of skin + NCs cultures for CC and CRBSI considering the best cut-off showing at least >90% of specificity to have a high negative predictive value using a ROC curve.ResultsWe collected a total of 167 catheters. The optimal cut-off of NCs culture was 1000 cfu/NC. The validity values for CC and CRBSI combining skin cultures and NCs cultures using the selected cut-off were, respectively: S, 42.9%/16.7%; SP, 83.6%/75.8%; PPV, 27.3%/2.5%; and NPV, 91.0%/96.0%.ConclusionsThe combination of skin cultures and quantitative NCs cultures could be used for ruling-out CC and CRBSI.     

下呼吸道细菌定植和稳定期COPD患者免疫状况的关系

目的探讨下呼吸道细菌定植和稳定期慢性阻塞性肺疾病(COPD)患者免疫状况的关系。方法选取2010年3月至2013年3月我院收治的稳定期COPD患者50例(病例组)和在我院接受健康体检并确认健康的志愿者50例(健康组),比较两组受试者的一般资料和免疫细胞水平。根据细菌定植情况将病例组分为定植组和未定植组,比较两组患者的炎性细胞因子水平。结果两组受试者的年龄、性别和体质量指数比较差异均无统计学意义(P>0.05),而吸烟量、FEV1和FEV1/FVC比较差异均具有统计学意义(P<0.05)。定植组与无定植组痰IL-8、痰IL-6、TNF-α、血IL-8和血hs-CRP水平比较差异均有统计学意义(P<0.05)。健康组和无定植组的辅助T细胞、抑制T细胞、巨噬细胞和中性粒细胞比较差异均无统计学意义(P>0.05)。定植组和无定植组、健康组的辅助T细胞、抑制T细胞、巨噬细胞和中性粒细胞水平比较差异均具有统计学意义(P<0.05)。结论下呼吸道细菌定植可导致稳定期COPD患者免疫功能下降,病情恶化。     

Vancomycin-resistant enterococci colonization in a neonatal intensive care unit: who will be infected?

Objective: To determine the incidence of vancomycin-resistant enterococcus (VRE) colonization in our neonatal intensive care unit (NICU) over five-year period, rate of progression to VRE infection and associated risk factors.

Methods: A retrospective analysis of a prospective surveillance for VRE colonization and health care-associated infections was made. Contact precautions were taken against colonization, although the application varied over the years due to repairs in the unit.

Results: VRE rectal colonization was detected in 200/1671 neonates (12%) admitted to NICU. It showed great interannual variability from 1.9% to 30.3%. Sytemic VRE infection developed in 6/200 VRE-colonized patients (3%) within a median of 9 days (range: 3–58 days). The risk factors for VRE infection development identified in the univariate analysis were long hospital stay (≥30 days), necrotizing enterocolitis, surgical procedure, extraventricular drainage, receipt of amphotericin B and receipt of glycopeptides after detection of VRE colonization. Crude in-hospital mortality was higher in neonates who developed a systemic VRE infection (p?<?0.001).

Conclusion: Maintaining physical conditions in the unit favorable for infection control and rational use of antibiotics are essential in the control of VRE colonization and resultant infections. Special attention should be directed to VRE-colonized babies carrying the risk factors.