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.     

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。     

Azithromycin resistance and its molecular characteristics in Neisseria gonorrhoeae isolates from a tertiary care centre in North India

Treatment guidelines for management of uncomplicated gonorrhoeae have been recently modified owing to alarming upsurge in azithromycin resistance. This study investigated the prevalence and genetic determinants of gonococcal azithromycin resistance in India. Four (5.7%) of 70 gonococcal isolates were resistant to azithromycin. Of 16 isolates investigated for molecular mechanisms of resistance, 13 (81.3%) and 6 (37.5%) isolates exhibited mutations in coding and promoter regions of mtrR gene, respectively. However, ermA, ermB and ermC genes or mutations in rrl gene were absent in all isolates. Azithromycin resistance is low in India posing no immediate threat to use of dual-therapy for syndromic management.     

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.     

常见抗生素与新型抗菌药物在临床上的研究应用进展

摘要：抗生素的研发与使用有效杀灭和抑制了众多病原菌，挽救了无数人的生命，但由于抗生素的不合理使用，导致细菌耐 药不断出现，耐药菌的感染已严重地威胁人类的生命健康。为此，本文主要对近年来临床上常用的抗生素如β-内酰胺类、喹诺酮 类、氨基糖苷类药物以及新型抗菌药物如抗菌肽和纳米颗粒的应用研究进行总结分析与探讨，为临床上治疗疾病提供一些参考。     

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.     

A new aspect of in vitro antimicrobial leukocyte- and platelet-rich plasma activity based on flow cytometry assessment

The current literature suggests that the antibacterial effect of leukocyte- and platelet-rich plasma (L-PRP) is directly related to platelet and leukocyte concentrations. The aim of this study was twofold: first, to evaluate the antimicrobial effect of L-PRP against selected bacterial strains in vitro, and second, to correlate this effect with leukocyte and platelet content in the final concentration. Blood was collected from 20 healthy males, and L-PRP, acellular plasma (AP), and autologous thrombin were consecutively prepared. Flow cytometry analysis of the blood, L-PRP, and AP was performed. The L-PRP gel, liquid L-PRP, and thrombin samples were tested in vitro for their antibacterial properties against seven selected bacterial strains using the Kirby–Bauer disk-diffusion method. There was notable antimicrobial activity against selected bacterial strains. No statistically significant correlations between antimicrobial activities and the platelet concentration in L-PRP were observed. Statistically significant positive correlations between selected leukocyte subtypes and antimicrobial activity were noted. A negative correlation was found between elevated monocyte count and antimicrobial activity of L-PRP against one bacterial strain studied. L-PRP possesses antimicrobial activity and can be potentially useful in the fight against certain postoperative infections. The bactericidal effect of L-PRP is caused by leukocytes, and there exists a relationship among selected leukocyte subtypes and L-PRP antimicrobial activity.     

Nano-silver modified porcine small intestinal submucosa for the treatment of infected partial-thickness burn wounds

Background and aimSilver has been widely used as a topical antimicrobial agent in burn wound care. In a previous study, we demonstrated the introduction of nano-silver particles to porcine small intestinal submucosa (NS-PSIS) led to significant enhancement in antibacterial property in repairing contaminated abdominal defect. In this study, we explored the efficacy of NS-PSIS in the treatment of Pseudomonas aeruginosa-infected partial-thickness burn wounds.Methods48 male Sprague-Dawley rats were divided into four groups of equal number. Standardized and reproducible Pseudomonas aeruginosa-infected partial-thickness thermal burns wound model were created using these rats. NS-PSIS, PSIS (porcine small intestinal submucosa) or lipido-colloid dressingss (Urgotul?) were tested for 14 days to assess their ability to heal the rats’ burn wounds. Control group was without any treatment after the establishment of infected burn-wound. The wound contraction rate, animal body weight change, histological examination, and the quantification of IL-6 and C-reactive protein (CRP) were measured to evaluate the healing effects.ResultsNS-PSIS significantly promoted wound healing and recovered the normal growth of rats. There were significantly lower expression levels of pro-inflammatory cytokine (IL-6) and CRP in NS-PSIS group as compared with the PSIS or Urgotul group in the treatment of infected partial-thickness burn wounds. Histological exams revealed significant less inflammatory cells infiltrating, more re-epithelization and neovascularization in NS-PSIS group. There were also less inflammatory cells infiltrations in the major organs in NS-PSIS group.ConclusionsNano-silver modified porcine small intestinal submucosa (NS-PSIS) can be used as a biological derivative dressing for the treatment of infected partial-thickness burn wounds.