On the possibility of photodynamic inactivation of tracheobronchial tree pathogenic microbiota using methylene blue (in vitro study)

BackgroundThe treatment of patients after mechanical ventilation of lungs suffering from a multi-species infection of the tracheobronchial tree can be complicated.. The situation is aggravated in patients with post-intubation tracheal stenosis, where infection plays a leading pathogenetic role in damage to the tracheal wall. As a result of such a pathological process, cicatricial stenosis of the trachea of purulent-inflammatory infectious genesis or infected tracheal stenosis (ITS) may occur.MethodsIn this work, we studied the possibility of photodynamic inactivation of pathogenic microbiota typical for patients with ITS using methylene blue (MB) as a photosensitizer.Results13 clinical isolates of 8 species of bacteria from 9 patients were susceptible to photodynamic inactivation with MB. 30 μM of MB at a light irradiation dose of 25 J/cm² and incubation with MB for 15 min allows to completely inactivate bacteria found in the tracheobronchial secretions of patients with ITS.ConclusionsMB retains its optico-physical properties in the range of 3–30 μM and provides effective inactivation of isolated Gram-positive and Gram-negative bacteria, including multi- and pan-resistant to antibiotics.     

Detection of vancomycin variable enterococci (VVE) among clinical isolates of Enterococcus faecium collected across India-first report from the subcontinent

PurposeEmergence of vancomycin variable enterococci (VVE) poses a challenge to empiric vancomycin therapy. Vancomycin-variable enterococci (VVE) are vanA-positive, yet phenotypically vancomycin-susceptible enterococci that can switch to a vancomycin-resistant phenotype when exposed to vancomycin. The aim of the present study was to determine the prevalence of VVE in India.MethodsIsolates of phenotypically vancomycin susceptible Enterococcus faecium from 20 tertiary care hospitals across India were collected and tested for the presence of vanA, vanR, vanS, vanB and vanC genes by conventional PCR using previously published primers. Isolates positive for vanA gene were considered as VVE.ResultsThe prevalence of VVE was 1.5% (5/340). Only one VVE isolate was positive for vanR and vanS, and all the isolates were negative for vanB and vanC.ConclusionsAlthough the prevalence is low, our finding emphasizes the importance of routinely screening for van genes in enterococci that are phenotypically susceptible. Silenced vanA able to escape detection and revert to resistance during vancomycin therapy represents a new challenge in clinical settings.     

Intrapartum fetal surveillance: a physiological approach

Continuous utero-placental circulation, and patent umbilical blood vessels ensure an uninterrupted transfer of oxygen and nutrients to the fetus as well as clearance of metabolic waste products. The onset of labour characterized by progressive and strong uterine contractions poses a threat to fetal oxygenation as a result of collapsing the spiral arterioles traversing the myometrium to supply the placental bed, and repetitive compression of the blood vessels within the umbilical cord. Human fetuses are equipped with compensatory mechanisms to cope with transient interruptions of blood supply during labour. The ability to compensate may be blunted in cases of poor fetal reserves, increased metabolic demand (macrosomia or maternal fever), and due to non-hypoxic pathways (e.g. chorioamniontis or fetal hypovolumia-hypotension syndrome). Intrapartum fetal surveillance involves prompt recognition of the features that signal the onset of fetal decompensation on the cardiotocograph (CTG) to ensure a timely intervention to avoid hypoxic-ischaemic encephalopathy (HIE) or perinatal deaths. This article summarises a ‘physiological approach’ to the interpretation of the CTG which, in places, conflicts with other current UK guidance.     

儿童肺炎克雷伯菌血流感染临床特征及菌株药物敏感性分析

摘要：目的 探讨儿童肺炎克雷伯菌血流感染(Klebsiella pneumoniae bloodstream infection, KPBSI)临床特征及肺炎克雷伯 菌(Klebsiella pneumoniae, KP)对常用抗菌药物的敏感性，为儿童KPBSI合理治疗提供参考。方法 回顾性分析2014年1月至2019 年12月在重庆医科大学附属儿童医院住院的KPBSI患儿临床资料。结果 共纳入110例患儿，64例(58.2%)为院内感染，72例 (65.5%)有基础疾病，以血液系统肿瘤最多见。110例患儿PRISM Ⅲ评分为16.0(7.0~20.8)，其中74例(67.3%)发生脓毒症，15例 (13.6%)发生脓毒性休克，18例(16.4%)发生呼吸衰竭，15例(13.6%)需有创机械通气，院内死亡共13例(11.8%)。KP菌株对阿米卡 星、碳青霉烯类抗菌药物敏感率＞90%，对头孢噻肟、头孢曲松和头孢他啶的敏感率分别为58.3%、60.9%和70.9%，对头孢哌 酮/舒巴坦和哌拉西林/他唑巴坦的敏感率分别为59.5%和82.7%。检出ESBLs+菌株39株(39/86，45.3%)，耐碳青霉烯类肺炎克雷 伯菌(CRKP)菌株10株(10/110，9.1%)，ESBLs+KP菌株和CRKP在各年龄组间分布无统计学差异。结论 儿童KPBSI多见于有基 础疾病的患儿，脓毒症、脓毒性休克和呼吸衰竭发生率高；KP菌株对头孢他啶和哌拉西林/他唑巴坦敏感性较高，可经验性治 疗轻症KPBSI患儿。     

毛霉目病原真菌的实验室鉴定及体外抗真菌药物敏感 性分析

摘要:目的以分子测序为参考 ,评估形态学、基质辅助激光解吸电离飞行时间质谱对毛霉目真菌的鉴定能力,分析毛霉目真菌对两性霉素B、泊沙康唑的体外药敏特点。方法收集 2018年1月-2022年2月广东省人民医院25例毛霉病住院患者标 本,进行镜检并对培养的茵落行形态学鉴定、质谱鉴定、分子测序和体外药敏试验。结果KOH 湿片法阳性率(76%)高于革兰染色法(32%),差异有统计学意义(P<0.05);形态学鉴定可将68%的菌株鉴定到属水平,3株鉴定错误,2株无法鉴定;将所 有菌株进行质谱鉴定,单用IVD和RUO数据库鉴定率分别为56%和44%,两库联合可将鉴定率提高为64%。毛霉目真菌对两性霉素B的抑制50%菌株生长的最小抑菌浓度(MIC3o)为1μg/mL,根霉属相比其他属对两性霉素B表现出较高的MIC 值,其中2株MIC>32 μg/mL,另2株MIC为8 μg/mL;根霉属对泊沙康唑的MICso为0.5 μg/mL,横梗霉属MICgo为4 μg/ mL,小克银汉霉属MICg0为2 μg/mL,有部分菌株表现出较低MIC值,同样亦有部分菌株对泊沙康唑表现出较高的MIC 值。结论 将传统镜检、培养与质谱技术和分子技术相结合,尽量将毛霉目真菌准确鉴定到种,并积极开展毛霉体外药敏试验,可为临床治疗提供参考依据。     

High frequency of extended-spectrum beta-lactamase-producing Enterobacteriaceae carriers at a Japanese long-term care hospital

IntroductionLong-term care hospitals (LTCHs) are at a high risk for the inflow and spread of antimicrobial resistance (AMR) pathogens. However, owing to limited laboratory resources, little is known about the extent to which AMR organisms are endemic.MethodsWe performed active surveillance for carbapenem-resistant Enterobacteriaceae (CRE) and extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-E) in newly admitted patients at Marugame Medical Center, a nearly 200-bedded LTCH located in Kagawa, Japan. From August to December 2021, we tested stool samples from patients wearing diapers and confirmed the genetic variants using specific PCR assays. We also collected clinical variables and compared them between AMR carriers and non-carriers.ResultsStool samples were collected from 75 patients, with a median age of 84 years. CRE strain was not detected, but 37 strains of ESBL-E were isolated from 32 patients (42.7%). During the study period, 4.9% of in-hospital patients (37 per 756 patients) were identified to be ESBL-E carriers in the routine microbiological processing, suggesting that active surveillance detected approximately 9-fold more ESBL-E carriers. The bla_CTX-M-9 group was the most common (38.5%), followed by the bla_TEM (26.9%). The clinical backgrounds of the ESBL-E non-carriers and carriers were not significantly different.ConclusionOur active screening demonstrated that nearly half of the patients hospitalized or transferred to a Japanese LTCH were colonized with ESBL-E. We highlight the enforcement of universal basic infection prevention techniques at LTCHs where patients carrying AMR pathogens gather.     

Performance of the new FilmArray Blood Culture Identification 2 panel and its potential impact on clinical use in patients with Gram-negative bacteremia

IntroductionRapid diagnostic tests have been developed recently for rapid species or resistance genes identification, offering the potential to improve the selection of appropriate antibiotics. The newly developed FilmArray Blood Culture Identification 2 (BCID2) panel, which can identify more species and resistance genes, such as extended-spectrum beta-lactamase, is expected to make an impact on antimicrobial practice.MethodsThe consecutive 50 inpatients with Gram-negative bacilli bacteremia were enrolled to this retrospective single-center study. In addition to the existing FilmArray Blood Culture Identification (BCID) panel, we have implemented BCID2 panel for positive blood culture. The sensitivity and specificity of BCID and BCID2 panel were respectively calculated, and a simulation study of time to effective, optimal and de-escalation therapy was performed based on BCID or BCID2 result.ResultsA total of 52 Gram-negative organisms in 50 patients were identified from blood cultures. Of these, 45 (87%) organisms were detected by BCID2 panel, which was more than BCID panel (41 organisms, 79%). BCID2 panel detected 5 CTX-M genes, which were concordant with conventional method. The time to effective therapy did not differ between BCID arm and BCID2 arm; however, the median time to optimal therapy (34 h in BCID arm and 26 h in BCID2 arm, P = 0.0007) and the median time to de-escalation therapy (42 h in BCID arm and 22 h in BCID2 arm, P = 0.0005) were significantly shortened.ConclusionsThis simulation study of BCID2 panel showed high sensitivity and specificity, and the potential impact on shortening the time to optimal and de-escalation therapy.     

Comparison of quantitative susceptibility mapping methods on evaluating radiation-induced cerebral microbleeds and basal ganglia at 3T and 7T

Quantitative susceptibility mapping (QSM) has the potential for being a biomarker for various diseases because of its ability to measure tissue susceptibility related to iron deposition, myelin, and hemorrhage from the phase signal of a T₂*-weighted MRI. Despite its promise as a quantitative marker, QSM is faced with many challenges, including its dependence on preprocessing of the raw phase data, the relatively weak tissue signal, and the inherently ill posed relationship between the magnetic dipole and measured phase. The goal of this study was to evaluate the effects of background field removal and dipole inversion algorithms on noise characteristics, image uniformity, and structural contrast for cerebral microbleed (CMB) quantification at both 3T and 7T. We selected four widely used background phase removal and five dipole field inversion algorithms for QSM and applied them to volunteers and patients with CMBs, who were scanned at two different field strengths, with ground truth QSM reference calculated using multiple orientation scans. 7T MRI provided QSM images with lower noise than did 3T MRI. QSIP and VSHARP + iLSQR achieved the highest white matter homogeneity and vein contrast, with QSIP also providing the highest CMB contrast. Compared with ground truth COSMOS QSM images, overall good correlations between susceptibility values of dipole inversion algorithms and the COSMOS reference were observed in basal ganglia regions, with VSHARP + iLSQR achieving the susceptibility values most similar to COSMOS across all regions. This study can provide guidance for selecting the most appropriate QSM processing pipeline based on the application of interest and scanner field strength.