Direct and Residual Microbicidal Efficacy of Various Antiseptics against Multi-Drug Resistant Bacteria

Background: Infections in ICU’s patients are known to often originate from the colonization of wounds by the patient’s endogenous microbiota, and to eventually lead to secondary sepsis. Aim: to compare in vitro the direct and residual effects after different exposure times of 4% chlorhexidine, and of 0.1% and 0.04% polyhexanide (in gel and solution forms), on ATCC-microorganisms, and too, on bacterial strains obtained from ICU patients. Methods: We used wild multi-drug resistant strains recently obtained from the wounds of patients hospitalized at ICU and reference strains from the American Type Culture Collection (ATCC). Chlorhexidine 4% was studied as a reference solution. The direct and residual effects of the 0.1% and 0.04% polyhexanide, in gel and solution forms, were analyzed using cotton germ carriers. To evaluate the direct effect, we exposed the strains to the antiseptic. To assess the residual effect, the germ-carriers were impregnated with antiseptic and were allowed to dry before we contaminated them. We inoculated the germ carriers in a culture medium with an inhibitor of antiseptic effect to count the number of surviving microorganisms. Findings: 0.1% Polyhexanide solution proved a direct and residual efficacy after 24 hours equivalent to 4% chlorhexidine. Is very important to highlight that this great efficacy did not change according to whether they were ATCC or multidrug-resistant strains. Conclusions: 0.1% polyhexanide demonstrated a great direct and residual efficacy (like 4% chlorhexidine), against multi-drug resistant strains isolated from ICU’s patients. Moreover, due to its few cytotoxicity against keratinocytes and fibroblasts can be an optimal antiseptic for burns, wounds or ulcers.

<i>In Vitro</i>Antibacterial Activity of Flavonoid Extracts of Two Selected Libyan Algae against Multi-Drug Resistant Bacteria Isolated from Food Products

This study aimed to evaluate the antibacterial activity of flavonoids extracted from two Libyan brown algae namely Cystoseira compressa and Padina pavonica using microwave-assisted extraction method against pathogenic bacteria isolated from meat, meat products, milk and dairy products (Staphylococcus aureus subsp. aureus (5 isolates), Bacillus cereus (3 isolates), Bacillus pumilus (1 isolate), Salmonella enterica subsp. enteric (4 isolates) and Enterohaemor-rhagic Escherichia coli O157 (EHEC O157) (4 isolates)). All of these isolates were muti-drug resistant with high MAR index. The results showed that C. compressa extract exhibited better and stronger antibacterial activities against the seventeen tested isolates with inhibition zones diameter ranged from 14 - 22 mm compared to P. pavonica extract which showed positive effect against 9 isolates with low inhibition zone ranged from 11 - 16.5 mm. Flavonoids extracted from C. compressa also displayed the best spectrum of bactericidal effect with a ratio MBC/MIC ≤ 4 obtained on all susceptible tested bacterial strains. Flavonoids and proanthocyanidins significantly contributed to the antibacterial properties. The mode of action of these active extracts is under investigation.

Bacterial contamination of orally-consumed crude herbal remedies:A potential source for multi-drug resistant pathogens in man

Objective:The acceptability of herbal remedies for alleviating discomforts and ill-health has become very popular, on the account of the increasing cost of allopathic medicine for personal health maintenance.The observable non-adherence of herbalists to the established World Health Organization(WHO) / National Agency for Food and Drug Administration Control(NAFDAC) regulations for the quality control of herbal medicines is an issue for concern.In view of this,34 popular and widely consumed crude herbal remedies in southwestern,Nigeria were screened for compliance with standard limits for bacterial contamination,bacteria flora and their antibiotic susceptibility pattern.Methods:Isolates recovered from samples were identified using the cultural, morphological and biochemical characteristics.They were also tested for drug sensitivity using standard procedures. Results:A heavy bacteria load ranging from 3.00×10~3-9.58×10~5 CFU/ML and 1.20×10~5- 5.41×10~5 CFU/ML was observed for water and spirit extracted preparations respectively.The bacteria flora cum contaminants were:Staphylococcus aureus,Bacillus cereus,Bacillus subtilis,Pseudomonas aeruginosa, Micrococcus luteus,Lactobacillus plantarum,Klebsiella pneumoniae,Escherichia coli,streptococcus,Shigella, Neisseria,Arthrobacter,Kurthia and Clostridium species.All the isolates were multi-drug resistant(MDR) strains.Conclusion:The crude herbal preparations consumed in Nigeria failed to comply with the internationally recognized standards regarding bacteria load and flora.The presence of MDR pathogens is of greatest concern. It poses a great risk to consumers health and could be a source of introducing MDR organisms into the human population.There is the need for the enforcement of established guidelines to ensure the safety of these preparations.

Analysis of Clinical Symptoms Improvement in Treatment of Severe Pneumonia Caused by Multi-drug Resistant Bacterial Infection by Bronchoscopy Alveolar Lavage

Objective:To explore the effects of bronchoscopy alveolar lavage in the treatment of severe pneumonia caused by multiple drug bacterial infection.Methods:A total of 84 patients with severe pneumonia infected by multi-drug resistant bacteria were randomly selected from Kunming Second People's Hospital,which is our hospital from January 2019 to December 2020 for this research.They were divided into a reference group and a study group using a digital table method,with 42 cases in each group.The reference group was given the routine treatment,the research group performed bronchoscopy alveolar lavage on this basis to observe the curative effect.Results:Before treatment,there was no significant difference in serum factor indexes and blood gas analysis indexes between the two groups of patients,P>0.05.After treatment,the time of fever,cough,moist rales disappearing and infection control time in the study group were shorter than those in the reference group,P<0.05.Serum tumor necrosis factorα(TNF-α),interleukin-6(IL-6)and interleukin-8(IL-8)levels were lower than the reference group,and the arterial partial pressure of oxygen(PO2)and oxygen saturation(SO2)were both lower than the reference group,P<0.05.The effective rate of the treatment in the study group was higher than that in the reference group,P<0.05.Conclusion:Bronchoscopic alveolar lavage treatment can effectively improve the clinical symptoms of patients with severe pneumonia caused by multi-drug resistant bacterial infection,and the effects are significant.

Antimicrobial activity of green tea extract against isolates of methicillin-resistant Staphylococcus aureus and multi-drug resistant Pseudomonas aeruginosa

Objective:To evaluate antibacterial activity of the Indonesian water soluble green tea extract,Camellia sinensis,against clinical isolates of methicillin-resistantStaphylococcus aureus (S.aureus)(MRSA)and multi-drug resistant Pseudomonas aeruginosa(MDR-P.aeruginosa).Methods:Antimicrobial activity of green tea extract was determined by the disc diffusion method and the minimum inhibitory concentration(MIC)was determined by the twofold serial broth dilutions method.The tested bacteria using in this study were the standard strains and multi-drug resistant clinical isolates of S.aureus and P.aeruginosa,obtained from Laboratory of Clinical Microbiology,Faculty of Medicine,University of Indonesia.Results:The results showed that the inhibition zone diameter of green tea extracts forS.aureus ATCC 25923 and MRSA were(18.970依0.287)mm,and(19.130依0.250)mm respectively.While the inhibition zone diameter forP.aeruginosa ATCC 27853 and MDR-P.aeruginosawere(17.550依0.393)mm and(17.670依0.398)mm respectively.The MIC of green tea extracts againstS.aureus ATCC 25923 and MRSA were 400μg/mL and 400μg/mL,respectively,whereas the MIC for P.aeruginosa ATCC 27853 and MDR-P.aeruginosawere 800μg/mL,and 800μg/mL,respectively.Conclusions:Camellia sinensisleaves extract could be useful in combating emerging drug-resistance caused by MRSA andP.aeruginosa.

Analysis of Influencing Factors and Predictive Models of Multidrug-resistant Bacterial Infection in Severe Patients

Objective:To investigate the influencing factors of multi-drug resistant bacterial infections in patients with severe disease and establish a predictive model.Methods:207 infected patients in our hospital from 2018 to May 2020 were selected for the study,of which 73 carried drug-resistant bacteria.Results:The risk factor network of people infected with multidrug resistant bacteria is higher than that of people infected with non-multidrug resistant bacteria,and the interaction between risk factors of the former is stronger.Conclusion:Antibiotics must be used appropriately after surgery.When the elderly was abnormal in indicators such as fever and procalcitonin in the ward,they should be considered as high-risk groups of MDRO infection.They need special care and preventive measures.

Management of Multi-Drug Resistant Methicillin Resistant <i>Staphylococcus aureus</i>Induced Pneumonia with New Antibiotic Adjuvant Entity: A Retrospective Study

Aim/Objective: Increase in incidences of pneumonia due to multi-drug resistant methicillin resistant Staphylococcus aureus (MRSA) in both community and health care settings is of great concern globally. Present study aims to retrospectively analyze the efficacy of new fixed dose combination with antibiotic adjuvant entity (FDC) in comparison with vancomycin to treat patients with multi-drug resistant MRSA pneumonia. Materials and Methods: During this retrospective study, case sheets of patients who were treated for MRSA pneumonia with vancomycin or fixed dose combination of vancomycin + ceftriaxone + adjuvant (FDC) between 20 March 2010 to 20 October 2014 at tertiary care center, were analyzed. Various demographic features, antibiotic therapy, length of treatment duration and the resulting efficacy were evaluated. Microbiological success was measured in terms of bacterial eradication, while clinical success was monitored in terms of complete omission of systemic signs and symptoms. Results: Among 136 patients analyzed, 113 cases were having positive culture for MRSA, and hence were further analyzed. Out of these 113 patients, empirical treatment with vancomycin was given in 59 patients and 54 patients were treated with FDC empirically. After initial culture reports, 22 patients showing resistance to vancomycin were shifted to FDC. Amidst all the patients, 24 (64.86%) of 37 from vancomycin group and 62 (81.57%) of 76 from FDC group achieved clinical success. 9 patients out of these failure cases were cured with FDC + colistin combination therapy. Failure rates in FDC treated patients were significantly low (6.57%) as compared to vancomycin group (13.51%). Conclusion: For the treatment of different types of multi-drug resistant MRSA pneumonia, the empirical intravenous FDC therapy was safe and well tolerated with higher efficacy than vancomycin. Most of the vancomycin failure cases responded to FDC therapy and were cured. This retrospective study also concludes that an alternative option of FDC + colistin is safe and effective to treat the patients which fail to respond to FDC monotherapy.

Multiple Antibiotic Resistant Index of Gram-Negative Bacteria from Bird Droppings in Two Commercial Poultries in Enugu, Nigeria

Antimicrobial resistance refers to the ability of microorganisms to grow in the presence of an antimicrobial agent at a concentration that will normally kill or inhibit their growth. Antimicrobial resistance has become a major global threat making treatment of infections tougher especially with high cost of treatment in humans and animals. This study was done to determine the Multiple Antibiotic Resistant Index (MARI) of Gram-negative bacteria from bird droppings in two commercial poultries in Enugu. Forty (40) samples were collected from each of the poultries. Isolates were identified by standard microbiological methods. The isolates identified were Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Citrobacter spp, Proteus spp. and, Enterobacter spp. Antibiotic susceptibility testing was carried out using disc diffusion technique. The organisms were tested against pefloxacin, augmentin (amoxicillin and clavulanic acid), ceftazidime, streptomycin, ciprofloxacin, gentamycin, cephalothin, neomycin and ofloxacin. The result of the susceptibility test showed that Proteus spp had the highest resistance and MARI value of 0.5 and 1.0 respectively. The other MARI values were Escherichia coli (0.9), Klebsiella pneumonia (0.9), Pseudomonas aeruginosa (0.8), Citrobacter spp (0.8) and Enterobacter spp (0.7). These results suggest that bacterial organisms from poultry source can contribute significantly to the spread of multi-antibiotic resistant organisms. This could arise from the indiscriminate use of antibiotics in bird feeds in poultries.

The Five Years Surveillance and Trends of Antibiotic Resistance in Some Common Gram Negative Bacteria at the Vietnam Military Hospital

The study is to identify trends and levels of antibiotic resistance of some common Gram-negative strains over time. The samples were collected from Vietnam Military Hospital 103 between 2014 and 2019. A total of 405 Acinetobacter baumannii., 528 Pseudomonas aeruginosa, 741 Escherichia coli, and 352 Klebsiella pneumoniae strains were identified and antimicrobial susceptibility was by Vitek system and Etest method. The multi-drug resistance (MDR) was major proportion of four common bacteria. In particular, there is a tendency to shift from MDR to Extended drug resistance (XDR) or possibly Pan drug resistant (pPDR). A. baumannii had the highest level of antibiotic resistance, namely, carbapenem (61.5% - 82.5%) and cephalosporin (72.7% - 88.7%). P. aeruginosa resisted most of commonly antibiotics, ranging from 50% to 70%. E. coli had a high resistance with antibiotics like ampicillin (87.2% - 97.6%) and the 3rd generation cephalosporins (up to 79.6%). K. pneumoniae resisted carbapenem from 14.7% to 44.4%, and other antibiotics with the higher rate of 40%. The collected data will be a prerequisite for further studies on mechanisms and factors related to antibiotic resistant bacteria, in order to find out a rational and effective using strategy of antibiotics.

Prevalence and Antimicrobial Resistance of Gram-Negative Bacteria Isolates in Shellfish Samples from Two River Estuaries in South-South Nigeria

Antibiotic resistant bacteria pathogens remain the leading cause of shellfish borne diseases and a major health threat to humans worldwide. The objectives of this study were to isolate, identify, and determine the antibiotic resistance patterns of Gram-negative bacteria from shellfish. We analyzed a total of 540 shellfish (117 clams, 88 oysters, and 136 periwinkles) samples collected from different vendors at Iko and Douglas Creeks in Akwa Ibom State, South-South Nigeria. Conventional cultural techniques, morphological, biochemical characteristics, and PCR amplification were used to identify the bacterial isolates. Antibiotic susceptibility tests (Kirby-Bauer disk diffusion method) and ESBL phenotype (disk) of the isolates were performed. One hundred and thirty-five (135) Gram-negative bacteria comprising 5 genera and 14 species were detected at a prevalence of: Alcaligenes faecalis TRB-7 38 (28.2%), Pseudomonas oryzihabitans strain KCB005 16 (11.9%), Paenalcaligenes retgerii strain B5 12 (8.9%) Pseudomonas aeruginosa JB2 10 (7.4%), Providencia stuartii DMC-28b 9 (6.7%), Alcaligenes species TLT151 8 (5.9%), Pseudomonas aeruginosa CIFRI DTSB1 7 (5.2%), Paenalcaligenes species UN24 7 (5.2%), Alcaligenes faecalis BT10 7 (5.2%), Vibrio species strain PrVy108 6 (4.4%), Pseudomonas xiamenensis C10-2 5 (3.7%), Providencia vemicola Bu15_38 4 (2.9%), Pseudomonas anguillisceptica 4029 3 (2.2%), and Pseudomonas aeruginosa N15-01092 3 (2.2%). All tested isolates showed various degrees of resistance to the thirteen antimicrobials evaluated. High levels of resistance (100%) to cefepime and imipenem were expressed by all isolates except the Providencia species. For the EBSL indicators, all isolates apart from Alcaligenes species were resistant (100%) to ceftriaxone. All Vibrio species were susceptible to norfloxacin, nalidixic acid, and ceftazidime. The identification of antibiotic resistant Gram-negative bacteria (GNARB) from shellfish in this study highlights the risk of disseminated multi-drug resistance—a serious public health concern.

Current concepts and future strategies in the antimicrobial therapy of emerging Gram-positive spontaneous bacterial peritonitis

Spontaneous bacterial peritonitis(SBP) is the most common infection in end-stage liver disease patients.SBP is defined as an ascitic fluid infection with a polymorphonuclear leucocyte count ≥ 250/mm^3 without an evident intra-abdominal surgically treatable source.Several mechanisms contribute to SBP occurrence,including translocation of gut bacteria and their products,reduced intestinal motility provoking bacterial overgrowth,alteration of the gut's barrier function and local immune responses.Historically,Gram-negative enteric bacteria have been the main causative agents of SBP,thereby guiding the empirical therapeutic choice.However,over the last decade,a worryingly increasing prevalence of Gram-positive and multi-drug resistant(MDR) SBP has been seen.Recently,the microbiological spectrum of SBP seems to have changed in Europe due to a high prevalence of Gram-positive bacteria(48%-62%).The overall proportion of MDR bacteria is up to 22%-73% of cases.Consequently,empirical therapy based on thirdgeneration cephalosporins or amoxicillin/clavulanic acid,can no longer be considered the standard of care,as these drugs are associated with poor outcomes.Theaim of this review is to describe,with an epidemiological focus,the evidence behind this rise in Gram-positive and MDR SBP from 2000 to present,and illustrate potential targeted therapeutic strategies.An appropriate treatment protocol should include daptomycin plus ceftaroline and meropenem,with prompt stepdown to a narrower spectrum when cultures and sensitivity data are available in order to reduce both cost and potential antibiotic resistance development.

Unresolved issues in the prophylaxis of bacterial infections in patients with cirrhosis

Bacterial infections are highly prevalent and a frequent cause of hospitalization and short-term mortality in patients with cirrhosis. Due to their negative impact on survival, antibiotic prophylaxis for bacterial infections in high-risk subgroups of patients with cirrhosis has been the standard of care for decades. Patients with prophylaxis indications include those at risk for a first episode of spontaneous bacterial peritonitis(SBP) due to a low ascitic fluid protein count and impaired liver and kidney function, patients with a prior episode of SBP and those with an episode of gastrointestinal bleeding. Only prophylaxis due to gastrointestinal bleeding has a known and short-time duration. All other indications imply longlasting exposure to antibiotics-once the threshold requirement for initiating prophylaxis is met-without standardized criteria for re-assessing antibiotic interruption. Despite the fact that the benefit of antibiotic prophylaxis in reducing bacterial infections episodes and mortality has been thoroughly reported, the extended use of antibiotics in patients with cirrhosis has also had negative consequences, including the emergence of multi-drug resistant bacteria.Currently, it is not clear whether restricting the use of broad and fixed antibiotic regimens, tailoring the choice of antibiotics to local bacterial epidemiology or selecting non-antibiotic strategies will be the preferred antibiotic prophylaxis strategy for patients with cirrhosis in the future.

西部地区某医院2010年度主要病原菌分布及其耐药性分析

目的了解西部地区某医院2010年临床分离主要病原菌分布及病原菌对常见抗菌药物的耐药状况。方法对医院2010年临床科室6 736份送检标本中培养分离出的1 381株(20.50%)条件致病菌进行分析。结果 1 381株临床分离菌中革兰阳性球菌占27.95%,革兰阴性杆菌占61.62%。耐甲氧西林金黄色葡萄球菌(MRSA)和表皮葡萄球菌检出率分别占10.38%和6.63%;革兰阳性球菌对万古霉素具有很好的敏感性。在革兰阴性杆菌中,产超广谱β-内酰胺酶的大肠埃希菌和肺炎克雷伯菌肺炎亚种分别占20.27%和8.39%;在非发酵菌中以铜绿假单胞菌和鲍曼不动杆菌最常见,绝大部分革兰阴性杆菌对亚胺培南具有很好的敏感性。结论细菌耐药呈上升趋势,多重耐药日趋严重,开展细菌耐药性监测工作和掌握细菌耐药性变迁动态,对于指导临床合理使用抗菌药物和有效控制院内感染具有重要意义。

流程再造模式对提高多部门参与多重耐药菌感染管理中的效果分析

目的:分析流程再造模式对提高多部门参及多重耐药菌(Multidrug-resistant bacterial,MDRB)感染管理中的效果,为指导医院多部门协作管理防控MDRB感染提供参考。方法:抽取2015年7月—2016年6月间MDRB感染患者110例资料为流程再造前组,另抽取2016年7月—2017年6月间流程再造后MDRB感染患者106例患者为流程再造后组;比较和分析流程再造多学科协作模式前后发现医院内MDRB感染报告时间、院内感染的检出率、院内感染发生率,以及比较和分析医务人员对MDRB的知晓率及防控措施依从性差异;标本的送检率、抗菌药物的使用率及DDDs的差异。结果:流程再造后组患者所在病区接收到从检验科发出的MDRB报告的时间明显早于流程再造前组(P<0.05),MDRB的检出率、医院感染率均低于流程再造前组(P<0.05),医务人员对MDRB的知晓率及防控措施的依从性均高于流程再造前组(P<0.05);流程再造后组标本的送检率高于流程再造前组,而抗菌药物使用率、使用强度(DDDs值)均低于流程再造前组。结论:流程再造模式的应用提高了各部门的参与度,也提高了院内感染管理的效率。

Infection-responsive polysaccharide-based drug-loaded nano-assembly for dual-modal treatment against drug-resistant bacterial lung infection

The escalating issue of lung infections induced by multi-drug resistant(MDR)bacteria is threatening human health.Thus,the development of efficient drug delivery systems is essential to eliminate MDR bacterial lung infections effectively.Herein,we designed inhalable drug-loaded nano-assemblies by the electrostatic interaction between negatively charged sodium alginate and a positively charged antibacterial polymer,quaternized polyethyleneimine(QPEI-C_(6)),as well as a kind of typical antibiotic for therapy of lung infection,azithromycin(AZT).By adjusting the feed ratios,we optimized the size of the nano-assembly to approximately 200 nm(STQ_(12)),which was beneficial for penetration through the mucus layer and biofilm.In the slightly acidic environment of the infected site,the nano-assembly could dissemble responsively and release AZT and QPEI-C_(6).Because of the combined bactericidal effect,STQ_(12)exhibited high bactericidal efficiency against MDR bacteria.In animal experiments,STQ_(12)showed notable efficacy against MDR bacterial lung infection.Gene transcriptomic results showed that the main effects of STQ_(12)against bacteria were through influencing the bacterial cell components and metabolic processes,and affecting their growth and reproduction.This work provides a promising strategy to treat MDR bacterium-induced lower respiratory tract infections.

Design, synthesis and antibacterial activity of novel pleuromutilin derivatives with 4H-pyran-4-one and pyridin-4-one substitution in the C-14 side chain

A series of novel pleuromutilin derivatives with 4H-pyran-4-one and pyridin-4-one substitution in the C-14 side chain have been designed and synthesized. In vitro antibacterial activity evaluation showed that most of the derivatives exhibited potent antibacterial activity against drug resistant Gram-positive strains. Compounds 12 a, 12 d, and 28 are the most active derivatives in this series, displaying activity comparable to that of retapamulin and BC-3781. As the metabolic stability of this series is not satisfactory, further modifications are going on to improve their pharmacokinetic profile.

医院多重耐药菌感染监测及分析

目的回顾性分析承德市中心医院临床分离多重耐药菌(multi-drug resistant bacterium,MDRB)感染情况及耐药性,为临床有效控制MDRB感染提供依据。方法对本院2008年-2012年检测到的MDRB进行分析,采用梅里埃ATB系统鉴定,K-B纸片扩散法进行药敏试验,按CLSI2010年标准判读药敏试验结果,采用WHONE5.4软件进行数据分析。结果耐甲氧西林金黄色葡萄球菌(MRSA)检出率为52.2%,未发现对万古霉素、利奈唑胺耐药金黄色葡萄球菌;2012年检测到2例万古霉素耐药肠球菌,均为屎肠球菌;大肠埃希菌、肺炎克雷伯杆菌、奇异变形杆菌中超广谱β-内酰胺酶(ESBLs)检出率分别为32.9%(477/1452)、20.0%(103/516)、14.8%(28/189),未发现对亚胺培南耐药肠杆菌。结论 5年来本院MDRB发生呈上升趋势,耐药性较严重。须加强MDRB监测,同时采取切实有效措施控制MDRB院内传播和暴发流行。

通过阻断调控基因ygrA挖掘海洋链霉菌OUC6819中抗MDR菌活性次级代谢产物

目的激活南海红树林来源链霉菌Streptomyces sp.OUC6819菌株中不表达或表达量低的隐性生物合成基因簇,挖掘具有优良多重耐药菌(MDR)抗菌活性的次级代谢产物。方法通过生物信息学分析推测Streptomyces sp.OUC6819基因组中可能的GntR家族调控子,采用PCR-targeting策略敲除其中的ygrA基因,HPLC分析突变株和野生株的发酵产物的差异,并比较粗提物对5株MDR菌抑制活性。结果 HPLC分析结果表明与野生株相比,突变株中化合物1和化合物2产量分别提高了9倍和7倍;突变株发酵液粗提物对其中3株MDR菌抑制活性较野生株明显提高。结论通过阻断GntR家族调控子ygrA激活了Streptomyces sp.OUC6819菌株中具有抗MDR菌活性次级代谢产物合成基因簇的表达,为从中发掘新的抗MDR菌抗生素奠定了必要基础;同时,将为其他海洋链霉菌中隐性基因簇的激活提供重要参考。

海洋芽孢杆菌B-9987中抗MDR菌活性成分研究

目的挖掘具有优良多重耐药菌(MDR)抗菌活性的次级代谢产物,为海洋新药研发提供分子多样性。方法对海洋芽孢杆菌B-9987进行大发酵,将发酵产物进行提取分离,每一步分离过程进行MDR活性追踪。结果 B-9987粗提物对4株MDR菌(金黄色葡萄球菌CCARM 3090、沙门氏菌CCARM 8250、大肠杆菌CCARM 1009、粪肠球菌CCARM 5203)具有良好的抗菌活性。通过HPLC分离纯化及MS、NMR等波谱分析获得了化合物1(Macrolactin F)和化合物2(Bacillaene A)。化合物1对MDR菌没有抗菌活性。由于化合物2对光、温度、氧气十分不稳定,无法直接测试活性。对含有化合物2的组分进行活性测试,确定了B-9987的MDR菌抗菌活性来自于Bacillaene类化合物。结论鉴定了B-9987中的抗MDR菌活性成分。

Nanomaterial-based strategies in antimicrobial applications:Progress and perspectives

The dramatic increase of microbial resistances against conventional available antibiotics is a huge challenge to the effective treatment of infectious disease and thus becoming a daunting global threat of major concern,which necessitates the development of innovative therapeutics.Nanomaterial-based antimicrobial strategies have emerged as novel and promising tools to combat lethal bacteria and recalcitrant biofilm,featuring the abilities to evade existing drug resistance-related mechanisms.In this review,recent advances in“state-of-the-art”nanosystems which acting either as inherent therapeutics or nanocarriers for the precise delivery of antibiotics,are comprehensively summarized.Those nanosystems can effectively accumulate at the infectious sites,achieve multifunctional synergistic antibacterial efficacy,and provide controlled release of antibiotics in response to endogenous or exogenous stimulus(e.g.,low pH,enzymes,or illumination).Especially,the nanoplatform that integrated with photothermal/photodynamic therapy(PTT/PDT)can enhance the bacterial destruction and biofilm penetration or ablation.In addition,nanoparticle-based approaches with enzymatically promoting bacterial killing,anti-virulence,and other mechanisms were also involved.Overall,this review provides crucial insights into the recent progress and remaining limitations of various antimicrobial nanotherapeutic strategies,and enlightens the further developments in this field simultaneously,which eventually benefiting public health.