Microbiology and risk factors for gram-positive Cocci bacteremia in biliary infections

Background:The rapid antibiotics treatment targeted to a specific pathogen can improve clinical outcomes of septicemia.We aimed to evaluate the clinical characteristics and outcomes of biliary septicemia caused by cholangitis or cholecystitis according to causative organisms.Methods:We performed a retrospective cohort study in 151 patients diagnosed with cholangitis or cholecystitis with bacterial septicemia from January 2013 to December 2015.All patients showed clinical evidence of biliary tract infection and had blood isolates that demonstrated septicemia.Results:Gram-negative,gram-positive,and both types of bacteria caused 84.1%(127/151),13.2%(20/151),and 2.6%(4/151)episodes of septicemia,respectively.The most common infecting organisms were Escherichia coli among gram-negative bacteria and Enterococcus species(Enterococcus casseliflavus and Enterococcus faecalis)among gram-positive bacteria.There were no differences in mortality,re-admission rate,and need for emergency decompression procedures between the gram-positive and gram-negative septicemia groups.In univariate analysis,previous gastrectomy history was associated with gram-positive bacteremia.Multivariate analysis also showed that previous gastrectomy history was strongly associated with gram-positive septicemia(Odds ratio=5.47,95%CI:1.19–25.23;P=0.029).Conclusions:Previous gastrectomy history was related to biliary septicemia induced by gram-positive organisms.This information would aid the choice of empirical antibiotics.

Obligate aerobic, gram-positive, weak acid-fast, nonmotile bacilli, Tsukamurella tyrosinosolvens: Minireview of a rare opportunistic pathogen

Tsukamurella species are obligate aerobic,gram-positive,weak acid-fast,nonmotile bacilli.They are found in various environments,such as soil,water,sludge,and petroleum reservoir wastewater,and belong to the order Actinomycetales.In 2016,there was a reclassification of species within the genus Tsukamurella,merging the species Tsukamurella tyrosinosolvens(T.tyrosinosolvens)and Tsukamurella carboxydivorans.Tsukamurella species are clinically considered to be a rare opportunistic pathogen,because most reported cases have been related to bacteremia and intravascular prosthetic devices and immunosuppression.To date,it has been isolated only from human specimens,and has always been associated with clinical disease;human infections are very rare.Reported infections have included pneumonia,brain abscesses,catheter-related bloodstream infections,ocular infections,bacteremia,and sepsis presenting with septic pulmonary emboli in patients who are immunocompromised.To date,there is no commercially available test for identification.On the other hand,sequence-based identification,including matrix-assisted laser desorption ionization time-of-flight mass spectrometry,is an alternative method for identifying clinical isolates that are either slow growers or difficult to identify through biochemical profiling.The golden standards for diagnosis and optimal management still remain to be determined.However,newer molecular biological techniques can provide accurate identification,and contribute to the appropriate selection of definitive therapy for infections caused by this organism.Combinations of several antimicrobial agents have been proposed for treatment,though the length of treatment for infections has yet to be determined,and should be individualized according to clinical response.Immunocompromised patients often experience severe cases due to infection,and life-threatening T.tyrosinosolvens events associated with dissemination and/or failure of source control have occurred.Favorable prognoses can be achieved through earlier identification of the cause of infection,as well as successful management,including appropriate antibiotic therapy together with source control.Further analyses of similar cases are required to establish the most adequate diagnostic methods and treatment regimens for infections.

Comparison of the serum contents of inflammatory mediators and oxidative stress mediators between patients with gram-positive bacteria and gram-negative bacteria infection

Objective: To compare the serum contents of inflammatory mediators and oxidative stress mediators between patients with gram-positive bacteria and gram-negative bacteria infection. Methods: Patients who were diagnosed with bloodstream bacterial infection in Zigong Third People's Hospital between March 2015 and April 2017 were selected as the research subjects and divided into gram-positive group and gram-negative group according to the results of blood culture and strain identification, and serum levels of inflammatory mediators PCT, IL-1β, IL-6, sTREM-1, TNF-α, NGAL, SAA, HPT and hs-CRP as well as oxidative stress mediators MDA, AOPP, TAC, CAT and SOD were determined. Results: Serum PCT, IL-1β, IL-6, sTREM-1, TNF-α, NGAL, SAA, HPT, hs-CRP, MDA and AOPP levels of gram-negative group were greatly higher than those of gram-positive group while TAC, CAT and SOD levels were greatly lower than those of gram-positive group. Conclusion: The changes of inflammatory mediators and oxidative stress mediators in the serum of patients with gram-negative bacteria infection are more significant than those of patients with gram-positive bacteria infection.

Coagulase-negative staphylococcus and enterococcus as predominant pathogens in liver transplant recipients with Gram-positive coccal bacteremia

Background Gram-positive bacteria such as Staphylococcus aureus have been a common cause of infection among liver transplant （LT） recipients in recent decades. The understanding of local epidemiology and its evolving trends with regard to pathogenic spectra and antibiotic susceptibility is beneficial to prophylactic and empiric treatment for LT recipients. This study aimed to investigate etiology, timing, antibiotic susceptibility and risk factors for multidrug resistant （MDR） Gram-positive coccal bacteremia after LT.Methods A cohort analysis of prospectively recorded data was performed to investigate etiologies, timing, antibiotic susceptibility and risk factors for MDR Gram-positive coccal bacteremia in 475 LT recipients.Results In 475 LT recipients in the first six months after LT, there were a total of 98 episodes of bacteremia caused by Gram-positive cocci in 82 （17%） patients. Seventy-five （77%） bacteremic episodes occurred in the first post-LT month.The most frequent Gram-positive cocci were methicillin-resistant coagulase-negative staphylococcus （CoNS, 46 isolates）,methicillin-resistant Staphylococcus aureus （MRSA, 13） and enterococcus （34, E. faecium 30, E. faecalis 4）. In all Gram-positive bacteremic isolates, 59 of 98 （60%） were MDR. Gram-positive coccal bacteremia and MDR Gram-positive coccal bacteremia predominantly occurred in patients with acute severe exacerbation of chronic hepatitis B and with fulminant/subfulminant hepatitis. Four independent risk factors for development of bacteremia caused by MDR Gram-positive coccus were： LT candidates with encephalopathy grades Ⅱ-Ⅳ （P=0.013, OR： 16.253, 95% CI：1.822-144.995）, pre-LT use of empirical antibiotics （P=0.018, OR： 1.029, 95% CI： 1.002-1.057）, post-LT urinary tract infections （P 〈0.001, OR： 20.340, 95% CI： 4.135-100.048） and abdominal infection （P=0.004, OR： 2.820, 95% CI：1.122-10.114）. The main infectious manifestations were coinfections due to gram-positive cocci and gram-negative bacilli.Conclusions Methicillin-resistant CoNS and enterococci are predominant pathogens among LT recipients with Gram-positive coccal bacteremia. Occurrences of Gram-positive coccal bacteremia may be associated with the severity of illness in the perioperative stage.

Improvement of antibacterial activity of copper nanoclusters for selective inhibition on the growth of gram-positive bacteria

In general, copper nanoclusters (CuNCs) possess very low or even virtually no bactericidal effect. Herein,we report a novel CuNCs possessing significantly high antibacterial activity, that is tannic acid (TA)capped CuNCs (TA-CuNCs). TA-CuNCs exhibit strong absorption and excitation-dependent fluorescence within pH 2-12, resulting from the functional groups of TA-CuNCs due to two prototropic equilibria,phenolphenolate and carboxyliccarboxylate. There exists synergistic effect of TA and copper nanoclusters which endows TA-CuNCs remarkable antibacterial capability as a microbicide, as characterized by the effective inhibition on the growth of gram-positive bacteria by damaging the cell membrane. By incubating 1 x 10~7 CFU/mL of gram-positive bacteria Staphylococcus aureus and Bacillus subtilis with 30 μg/mL of TA-CuNCs for 10 min, the bacteria are completely inhibited, while under same conditions the viabilities of gram-negative bacteria Escherichia coli 0157:H7 and Pseudomonas aeruginosa remain 85.0%, 72.0%, respectively. In addition, TA-CuNCs exhibit low cytotoxicity and favorable biocompatibility demonstrated by standard methyl thiazolyl tetrazolium (MTT) assay with HepG2 and 293 Tcells, giving rise to cell viability of 94.2% for HepG2 and 96.7% for 293 T by incubating 10~6 cell/mL with 200 μg/mL of TA-CuNCs for 24 h. These results make TA-CuNCs a potential alternative as bactericide for infection treatment caused by gram-positive bacteria.

Analysis of Gram-positive bacterial infection in patients following liver transplantation

Background Liver transplantation is the most effective treatment for patients with end-stage liver failure, however infection after transplantation is a serious clinical complication. The purpose of this research was to investigate the molecular epidemiology and the influence of multidrug-resistant Gram-positive infection in patients, following liver transplantation, to provide reference for clinical treatment and prevention of Gram-positive bacterial infection. Methods We isolated and detected bacteria from phlegm, throat swabs, urine, wound or wound secretions, blood, and fecal samples from 221 liver transplant patients in our hospital from January 2007 to April 2010. All isolated bacterial strains were identified and tested by minimal inhibitory concentration （MIC） drug-sensitive detection using the BioMerieux ATB bacterial identification instrument and repetitive extragenic palindromic-polymerase chain reaction （REP-PCR） detection of bacterial homology. Risk factors were calculated by multivariate Logistic regression analysis. Results We collected 250 specimens from 221 patients hospitalized following liver transplantation surgery, of which 29 patients developed multiple infections. Sixty-five Gram-positive bacterial strains were isolated from different specimens from 53 infectious patients. We detected 29 multidrug-resistant Gram-positive strains from 29 patients （44.62%）, including 20 Staphylococcus aureus （S. aureus） strains （68.97%） and nine Enterococcus strains （31.03%）. All 20 S. aureus strains were highly resistant to aminoglycosides （gentamicin）, cephalosporins （cefoxitin）, quinolones （ciprofloxacin and levofloxacin）, lincomycins （clindamycin）, penicillin, and erythromycin. The resistance rate reached 100% in some cases. The S. aureus strains were highly sensitive to vancomycin and oxazolidinone （linezolid）, with MIC50 〈2 pg/ml for both. The nine Enterococci strains were also highly resistant to aminoglycosides, quinolones, and penicillins, and highly sensitive to vancomycin （MIC50 〈2 pg/ml） and oxazolidinone （MIC50 〈1 pg/ml）. Using REP-PCR detection, S. aureus was divided into five genotypes with 14 B-type strains. Enterococcus was divided into 11 genotypes, with two D-type strains, two G-type strains, and two K-type strains. The risk factors for Gram-positive bacterial infection in patients following liver transplantation were preoperative use of antibiotics （OR=3.949, P=-0.004）, high intra-operative blood input （OR=1.071, P=0.005）, and postoperative renal failure （OR=5.427, P=-0.043）. Conclusions S. aureus and Enterococcus were the main pathogens causing infection following liver transplantation in patients with drug-resistant Gram-positive bacterial infection. The isolated strains were resistant to multiple antibiotics. B-type S. aureus strains were predominant. Reasonable use of antibiotics, decreasing intra-operative blood input, and preventing post-operative renal failure may reduce Gram-positive bacterial infections and the appearance of drug-resistant strains following liver transplantation.

A widespread response of Gram-negative bacterial acyl-homoserine lactone receptors to Gram-positive Streptomyces γ-butyrolactone signaling molecules

Cell-cell communication is critical for bacterial survival in natural habitats,in which miscellaneous regulatory networks are encompassed.However,elucidating the interaction networks of a microbial community has been hindered by the population complexity.This study reveals thatγ-butyrolactone(GBL)molecules from Streptomyces species,the major antibiotic producers,can directly bind to the acyl-homoserine lactone(AHL)receptor of Chromobacterium violaceum and influence violacein production controlled by the quorum sensing(QS)system.Subsequently,the widespread responses of more Gram-negative bacterial AHL receptors to Gram-positive Streptomyces signaling molecules are unveiled.Based on the cross-talk between GBL and AHL signaling systems,combinatorial regulatory circuits(CRC)are designed and proved to be workable in Escherichia coli(E.coli).It is significant that the QS systems of Gram-positive and Gram-negative bacteria can be bridged via native Streptomyces signaling molecules.These findings pave a new path for unlocking the comprehensive cell-cell communications in microbial communities and facilitate the exploitation of innovative regulatory elements for synthetic biology.

Effect of colloid-size copper-based pesticides and wood-preservatives against microbial activities of Gram-positive Bacillus species using five-day biochemical oxygen demand test

Copper-based pesticides and wood preservatives could end up in the environment during production,use,and end-of-life via different pathways that could cause unintended ecolog-ical and adverse health effects.This paper provides the effect of colloid-size Cu-based pesti-cides(CuPRO and Kocide),micronized Cu azole(MCA-1 and MCA-2)and alkaline Cu quater-nary(ACQ)treated woods,Cu^(2+),Cu^(2+) spiked untreated wood(UTW),and CuCO_(3) solutions against Gram-positive Bacillus species using five-day biochemical oxygen demand(BOD 5)stan-dard test.The total Cu leached from MCA-1,MCA-2,and ACQ in Milli-Q water after 5 days were -0.1,-0.11,and -0.64 g/kg of wood,respectively.However,the form of Cu leached from MCA woods was mostly ionic(>90%).The total organic carbon(TOC)content of any tested wood(UTW/MCA-1/MCA-2/ACQ)was -99%of its corresponding total carbon(TC)content,whereas the TOC of any tested wood sawdust exceeded that of its corresponding piece/block by>300%.The dissolved oxygen(DO)consumption value in the presence of Cu^(2+),CuCO_(3),CuPRO,and Kocide solutions was significantly influenced by Cu particles/ions.However,the DO consumption value in the presence of UTW/MCA-1/MCA-2/ACQ woods was significantly influenced by organics leached from woods.On the other hand,the DO consumption of MCA sawdust was greater than(300%)that of MCA pieces/block.The findings of this study provide more insight into how organics leached from woods significantly reduce the toxic effects of Cu ions against Gram-positive Bacillus species.

Selective inactivation of Gram-positive bacteria in vitro and in vivo through metabolic labelling

Bacterial infections are grave threats to human health,particularly those caused by the most common Grampositive bacteria.The massive administration of broad-spectrum antibiotics to treat various bacterial infections has led to the evolution and spread of drug resistance.As a universal antimicrobial technique unapt to induce drug resistance,photothermal therapy(PTT)is attracting extensive attention in recent years.However,its unspecific killing capability and side effects towards adjacent mammalian cells severely impede the practical applications.Herein,we proposed a metabolic engineering strategy to selectively inactivate Gram-positive bacteria by PTT.A bioorthogonal photothermal agent was prepared by the conjugation of IR-780 iodide and dibenzocyclooctyne(IR780-DBCO).Upon pre-metabolizing with 3-azido-D-alanine,Gram-positive bacteria rather than Gramnegative ones,such as Staphylococcus aureus and vancomycinresistant Enterococcus faecalis(VRE),could be specifically tied up by the explosive IR780-DBCO via copper-free click chemistry.Thereafter,they spontaneously detonated under 15 min near-infrared light irradiation and inactivated nearly 100% Gram-positive bacteria in vitro.Moreover,superbug VRE-induced infection was significantly inhibited by this approach in a mouse skin wound model.This metabolic labelling-based photothermal ablation strategy specific to Gram-positive microbes would stimulate the development of precise antibacterial candidates for preclinical applications.

Virus-inspired nanoparticles as versatile antibacterial carriers for antibiotic delivery against Gram-negative and Gram-positive bacteria

Infectious diseases become one of the leading causes of human death. Traditional treatment based on classical antibiotics could not provide enough antibacterial activity to combat bacterial infections due to low bioavailability, even leading to antibiotic resistance. In recent years, biomimetic delivery systems have been developed to improve drug therapy for various diseases, such as malignant tumor and cardiovascular disease. In this work, we designed virus-inspired nanodrugs(VNDs) through co-assembly of amphiphilic lipopeptide dendrons and poly(lactic-co-glycolic acid) polymers for high-efficiency antibiotic delivery. These VNDs had well-defined and stable nanostructures for tetracycline encapsulation and delivery. The VNDs were capable of promoting antibiotic internalization and enhancing their antibacterial effects against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus. Additionally, no obvious cytotoxicity of VNDs was observed to human cell lines. This work successfully demonstrated the virus-mimetic nanoparticles served as promising and applicable antibiotic delivery platform for antibacterial treatment.

Antibacteria Activity of Peganum harmala and Haloxylon salicornicum Leaves Extracts

The use of antibiotics in humans and animals has been marked as a significant step in health due to their effectiveness in controlling and treating bacterial infections. The misuse and overuse of antibiotics have been identified as risk factors for bacterial resistance since microorganisms adapt and develop mechanisms to defend against antibiotics. According to the Centers for Disease Protection and Control (CDC), around 23,000 individuals die every year in the United States due to antibiotic resistance complications. As a result, a demand for alternative treatments has been a goal for scientists as the microbes adapt to selective pressure. The aim of this study is to test the antibacterial activity of leaf extracts of Peganum harmala and Haloxylon salicornicum on both Gram-positive and Gram-negative bacteria on various mediums. The results of the study showed that both P. harmala and H. salicornicum inhibited the bacterial growth in two different media. The results were also compared with different common antibiotics used in both human’s and animal’s fields and showed a promising outcome as alternative antibiotics.

Causative Microorganisms Isolated from Patients with Intra-Abdominal Infections and Their Drug Resistance Profiles:An 11-Year(2011–2021)Single-Center Retrospective Study

Objective To investigate the distribution and antimicrobial susceptibility of causative microorganisms recovered from patients with intra-abdominal infections(IAIs).Methods A total of 2,926 bacterial and fungal strains were identified in samples collected from 1,679 patients with IAIs at the Peking Union Medical College Hospital between 2011 and 2021.Pathogenic bacteria and fungi were identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.Antimicrobial susceptibility testing(AST)was performed using the VITEK 2 compact system and the Kirby–Bauer method.AST results were interpreted based on the M100-Ed31 clinical breakpoints of the Clinical and Laboratory Standards Institute.Results Of the 2,926 strains identified,49.2%,40.8%,and 9.5%were gram-negative bacteria,gram-positive bacteria,and fungi,respectively.Escherichia coli was the most prevalent pathogen in intensive care unit(ICU)and non-ICU patients;however,a significant decrease was observed in the isolation of E.coli between 2011 and 2021.Specifically,significant decreases were observed between 2011 and 2021 in the levels of extended-spectrumβ-lactamase(ESBL)-producing E.coli(from 76.9%to 14.3%)and Klebsiella pneumoniae(from 45.8%to 4.8%).Polymicrobial infections,particularly those involving co-infection with gram-positive and gram-negative bacteria,were commonly observed in IAI patients.Moreover,Candida albicans was more commonly isolated from hospital-associated IAI samples,while Staphylococcus epidermidis had a higher ratio in community-associated IAIs.Additionally,AST results revealed that most antimicrobial agents performed better in non-ESBL-producers than in ESBL-producers,while the overall resistance rates(56.9%–76.8%)of Acinetobacter baumanmii were higher against all antimicrobial agents than those of other common gram-negative bacteria.Indeed,Enterococcus faecium,Enterococcus faecalis,S.epidermidis,and S.aureus were consistently found to be susceptible to vancomycin,teicoplanin,and linezolid.Similarly,C.albicans exhibited high susceptibility to all the tested antifungal drugs.Conclusion The distribution and antimicrobial susceptibility of the causative microorganisms from patients with IAls were altered between 2011 and 2021.This finding is valuable for the implementation of evidence-based antimicrobial therapy and provides guidance for the control of hospital infections.

Virulence Factors and Biofilm Formation in Vancomycin Resistant Enterococcus faecalis and Enterococcus faecium Isolates in Brazil

In this work, we evaluated biofilm formation of Vancomycin Resistant of E. faecalis and E. faecium (VRE) in different culture media and adhesion substrate, as well as cellular hydrophobicity and presence of virulence genes. For this, 35 isolates were collected from a public hospital in Recife, Pernambuco, Brazil and identified by the Matrix-Assisted Laser Desorption Ionization - Time-of-flight - Mass Spectrometry (MALDI-TOF-MS) technique. Biofilm formation was analyzed by the Crystal Violet (CV) method and fluorescence microscopy, cellular hydrophobicity by hydrocarbon interaction and the presence of gelE, esp and asa1 genes by Polymerase Chain Reaction (PCR). 12 isolates were identified as E. faecalis and 23 as E. faecium. Most were obtained in Coronary Units (40.0%) and Intensive Care Unit (31.4%). E. faecium isolates were more resistant to the antibiotics tested than E. faecalis;however, E. faecalis stood out as a biofilm producer. Regarding the presence and gene frequency, it was observed that gelE (54.3%) and esp (54.3%) were the most prevalent, followed by asa1 (22.9%). When comparing the gene frequency, it was observed that gelE and esp were predominant (48.6% for both species), while asa1 was more frequent in E. faecalis (20.0%). The data presented here are worrying, because they reveal the virulence potential of isolates VRE, which contributes to the dissemination and persistence of these pathogens in the hospital environment.

Purification and Antimicrobial Activity of Antimicrobial Protein from Brown-spotted Grouper, Epinephelus fario

Antimicrobial proteins and peptides had been found from a wide variety of organisms in the last few years These molecules have attracted much research interest because of their biochemical diversity, broad specificity on anti-viral, anti-bacterial, anti-fungi, anti-protozoan parasites, anti-tumoural, and wound-healing effects. Antimicrobial proteins and peptides play key roles in innate immunity. They interact directly with bacteria and kill them. The brown-spotted grouper, Epinephelusfario, is an important marine fish cultured in southem China. Recently, bacteria and virus have caused high mortality in E. fario cultures, but its endogenous antimicrobial peptides and proteins have not been explored. An antimicrobial component was found from the skin homogenate of E. fario. After the skin homogenate was digested with trypsin, its antimicrobial activity was lost, which showed that the antimicrobial component is a protein. The antimicrobial protein （Efap） was purified from the skin homogenate of E. fario by successive ion-exchange and gel filtration chromatography. Efap was demonstrated to be single protein band by SDS-PAGE, with the apparent molecular weight of 41 kD. Efap exhibited antimicrobial activity both for the Gram-positive bacteria, Staphylococcus aureus, Micrococcus luteus and Bacillus subtilis, and for the Gram-negative bacteria, Vibrio alginolyticus, Vibrio parahaemolyticus, Vibrio fluvialis, Pasteurella multocida, Aeromonas hydrophila, Eschrrichiu coli, and Pseudomonas aeruginosa. Except A. hydrophila, P. aeruginosa, and E. coli （MIC〉20 mol/L）, most of the tested Gram-negative bacteria were sensitive to Efap （MIC〈20 mol/L）. Interestingly, Efap showed potent antimicrobial activity against Gram-positive bacteria S. aureus （MIC 5-10 mol/L） but comparatively weak antimicrobial activity against M. luteus and B. subtilis. The broad antimicrobial activities of Efap suggest that it contributes to the innate host defence of E. fario.

A Rapid and Efficient Method for Preparing Genomic DNA from Microbacterium sp.

A new method was used to preparing genomic DNA from Microbacterium sp.quickly and efficiently.DNA quantity and purity was measured by UV absorbance.Integrity of the genomic DNA was tested by agarose gel eletrophoresis.The DNA prepared by this method was sufficiently pure for PCR.This method saves time and cost,practices easily as well.

Accumulation of Rare Earth Elements in Various Microorganisms

The removal of rare earth elements （REEs） from solution in various microorganisms was examined. Seventy-six strains from 69 species （22 bacteria, 20 actinomycetes, 18 fungi, and 16 yeasts） were tested. Initially, Sm was used to test the removal capabilities of the various organisms. Gram-positive bacteria, such as Bacillus licheniformis, B. subtilis, Brevibacterium helovolum, and Rhodococcus elythropolis, exhibited a particularly high capacity for accumulating Sm. In particular, the B. lichemiformis cells accumulated approximately 316 μmol Sm per gram dry wt. of microbial cells. A full suite of screenings was then conducted to compare the abilities of the organisms to remove Se, Y, La, Er, and, Lu from solution. Tests were done with solutions containing one REE at a time. Accumulation was nearly identical for the various metals and organisms. However, when solutions with equimolar amounts of two REEs were used, preferential removal from solution was observed. When an Eu/Gd solution was used, gram-positive bacteria removed more Eu and Gd as compared to actinomycetes. When Eu/Sm combination was used, gram-positive bacteria removed equal mounts of both metals and some actinomycetes removed more Eu. The selective removal was quantified by calculating separation factors （S. F.）, which indicated that Streptomyces levoris cells accumulated the greatest proportion of Eu. The removal of REEs from a solution containing five metals （Y, La, Sm, Er, and Lu） was then examined. Mucorjavanicus preferentially accumulated Sm and S. flavoviridis preferentially accumulated Lu. The effects of pH and Sm concentration on the accumulation of Sm by B. licheniformis were also examined. Accumulation increased at higher pH and at greater solution concentrations.

A middle-aged lady with a pyogenic liver abscess caused by Clostridium perfringens

The pyogenic liver abscess caused by Clostridium perfringens (C. perfringens ) is a rare, but rapidly fatal infection. It is usually associated with malignancy and immunosuppression. We report the case of 50-year-old lady with the secondary liver metastases from rectal cancer presented with fever and epigastric pain. The identification of Grampositive bacilli septicaemia, the presence of gas-forming liver abscess and massive intravascular hemolysis should lead to the suspicion of C. perfringens infection. Here we review twenty cases published since 1990 and their clinical features are discussed. The importance of "an aggressive treatment policy" with multidisciplinary team approach is emphasized.

Selective intestinal decontamination for the prevention of early bacterial infections after liver transplantation

Bacterial infection in the first month after liver transplantation is a frequent complication that poses a serious risk for liver transplant recipients as contributes substantially to increased length of hospitalization and hospital costs being a leading cause of death in this period. Most of these infections are caused by gramnegative bacilli, although gram-positive infections, especially Enterococcus sp. constitute an emerging infectious problem. This high rate of early postoperative infections after liver transplant has generated interest in exploring various prophylactic approaches to surmount this problem. One of these approaches is selective intestinal decontamination(SID). SID is a prophylactic strategy that consists of the administration of antimicrobials with limited anaerobicidal activity in order to reduce the burden of aerobic gram-negative bacteria and/or yeast in the intestinal tract and so prevent infections caused by these organisms. The majority of studies carried out to date have found SID to be effective in the reduction of gram-negative infection, but the effect on overall infection is limited due to a higher number of infection episodes by pathogenic enterococci and coagulase-negative staphylococci. However, difficulties in general extrapolation of the favorable results obtained in specific studies together with the potential risk of selection of multirresistant microorganisms has conditioned controversy about the routinely application of these strategies in liver transplant recipients.

Antibacterial activity of leaves extracts of Trifolium alexandrinum Linn,against pathogenic bacteria causing tropical diseases

Objective:To investigate antibacterial potential of Trifolium alexandrinum(T.alexandrinum) Linn,against seven gram positive and eleven gram negative hospital isolated human pathogenic bacterial strains responsible for many tropical diseases.Methods:Non-polar and polar extracts of the leaves of T.alexandrinum i.e.,hexane,dichloromethane(DCM),ethyl acetate(EtOAc), methanol(MeOH) and aqueous(AQ) extracts at five different concentrations(1,2,5,10 and 15 mg/ mL) were prepared to evaluate their antibacterial value.NCCL standards were strictly followed to perform antimicrobial disc susceptibility test using disc diffusion method.Results:Polar extracts demonstrated significant antibacterial activity against tested pathogens.EtOAc and MeOH extracts showed maximum antibacterial activity with higher inhibition zone and were found effective against seventeen of the tested pathogens.While AQ plant extract inhibited the growth of sixteen of the test strains.EtOAc and MeOH plant extracts inhibited the growth of all seven gram positive and ten of the gram negative bacterial strains.Conclusions:The present study strongly confirms the effectiveness of crude leaves extracts against tested human pathogenic bacterial strains causing several tropical diseases.Since Egyptian clover is used as a fodder plant,it could be helpful in controlling various infectious diseases associated with cattle as well.

Study on the synthesis and antimicrobial activity of novel cationic porphyrins

A novel series of quaternary ammonium cationic derivatives based on tetrapyridyl-porphyrin was synthesized. All the compounds were evaluated for their in vitro antibacterial activities against S. aureus, E. coli and P. aeruginosa, and antifungal activities against C. albicans, where microorganisms were exposed and unexposed to the irradiation. The results revealed that some of these compounds, especially, 3a and 4a displayed satisfactory antibacterial activity against Gram-positive bacteria S. aureus and moderate antifungal activity against C. albicans. Unfortunately, Gram-negative bacteria P aeruginasa was resistant to all compounds. The antimicrobial activity was found to be sensitive to the functional groups attached on the aromatic ring and the complex metal in the porphyrin ring, and decreased with the increase of electron-withdrawing capability of the functional groups. These preliminary results suggested that the remarkable antibacterial efficiency against S. aureus makes these substances promising antimicrobial agents.