Greater Antibacterial Activity Research Articles

Antibacterial and Antifungal Effects of Various Commercial Plant Extracts

The antimicrobial activities of valex (the extract of valonia), the extracts of mimosa bark, gallnut powders, Salvia aucheri Bentham var. aucheri and Phlomis bourgei Boiss were studied. The antimicrobial activity of the above plants was evaluated by the disk diffusion method using Bacillus brevis FMC 3, Bacillus subtilis IMG 22, Bacillus cereus EÜ, Escherichia coli DM, Pseudomanas aeruginosa DSM 50071, Staphylococcus aureus Cowan 1, Listeria monocytogenes A, Micrococcus luteus LA 2971, Klebsiella pneumoniae FMC 5, Mycobacterium smegmatus RUT, Proteus vulgaris FMC 1 bacteria, and Alternaria alternata MDC 97, Penicillium italicum MDC 101, Fusarium equiseti C, Candida albicans CCM 314 fungi. The results indicated that mimosa bark extracts had the greatest antibacterial activity, followed by the valex, gallnut powders, Salvia aucheri var. aucheri and Phlomis bourgei extracts, respectively. Furthermore, it was found that gallnut powders and the extracts of mimosa bark contained high amounts of tannins and showed antifungal activity.

Bactericidal Activity of 5 Beta-Lactam Antibiotics Against Streptococcus Pneumoniae

Assays were performed to determine bactericidal activity as a function of time (1, 3, 5, and 7 hours) and of the concentration (1, 2, 4, and 8 MIC) of antibiotics for 2 penicillin-sensitive strains ofStreptococcus pneumoniae (MIC<0.06 mg/L), 2 strains with moderate penicillin sensitivity (MIC=0.125 mg/L) and 2 penicillin-resistant strains (MIC-2 mg/L). The beta-lactam antibiotics studied were penicillin, amoxicillin, cefotaxime, imipenem and cefpirome. Imipenem was the antibiotic with the greatest antibacterial activity, followed by amoxicillin. The bactericidal activity of all the antibiotics was greater against the penicillin-sensitive strains than against those strains with some degree of resistance. However, the bactericidal activity observed for cefpirome suggests that further studies are necessary to determine the value of this antibiotic in the treatment of severeS. pneumoniae infections.

Psychosocial interventions for cardiopulmonary patients: a guide for health professionals, W.M. Sotile. Human Kinetics, Champaign, Illinois (1996), 410, Price £29.50

Chitosan is produced by thermochemical alkaline deacetylation of chitin, but the process is usually environmentally problematic. In the present study, Illex argentinus squid pen chitin, after de-proteinization and demineralization, was pretreated with a compressional-puffing (CP) process under various puffing pressures. The CP process facilitated the increase of the crystalline index and degree of deacetylation of chitins. The CP-treated chitins were subjected to further extraction of chitosan, and four chitosan isolates (CI1–CI4) were obtained. The CP process was found to have beneficial effects in terms of increased extraction yield and increased antibacterial activity of the extracted chitosans. Moreover, the antibacterial property of the extracted chitosans seemed to be negatively related to their molecular weight (MW). Our findings showed that CI4 exhibited the highest extraction yield and the greatest antibacterial activity, and thus we recommend it as a safe and potent antibacterial agent for food, biomedicine, and other industrial usages.

Antibacterial activity of lactoferricin, lysozyme and EDTA against Salmonella enteritidis

Abstract The antibacterial activity of a pepsin digest of bovine lactoferrin, containing the peptide lactoferricin B against Salmonella enteritidis was studied under various conditions. The digest had greater antibacterial activity than lactoferrin in 1% peptone, was bactericidal and also increased the permeability of the outer membrane of the bacteria as demonstrated by plating on bile salts agar. The antibacterial activity was inhibited in richer media, such as tryptic soy broth or milk-based or soy-based infant formula. Addition of lysozyme or EDTA or both, to the lactoferrin digest resulted in increased antibacterial activity of the mixture. Lysosyme or EDTA alone had little or no activity against S. enteritidis . The increase in antibacterial activity obtained with the addition of lysozyme and EDTA to the lactoferrin digest was not sufficient to overcome inhibition by components of the richer media.

Brodimoprim synergy against Enterococcus faecalis evaluated in vitro.

Combinations of either brodimoprim or trimethoprim plus either carbenicillin, gentamicin, ciprofloxacin or rifampicin showed synergy at sub-inhibitory concentrations against both Enterococcus faecalis NCTC 5957 and 775. Brodimoprim alone and in combination showed greater antibacterial activity against both strains of E. faecalis than trimethoprim. MBCs of brodimoprim and trimethoprim were 14.4 and 25.6 mg/L for E. faecalis NCTC 5957 and 7.2 and 12.8 mg/L for E. faecalis NCTC 775. Combinations of either brodimoprim or trimethoprim plus the other antibacterial agents, except gentamicin and dibromopropamidine isethionate, were bactericidal at achievable plasma concentrations. Viable count determinations of cultures of both test organisms in the presence of 3/4 of the MIC of each of the four antibiotics and the two antifolates alone and combinations of each antibiotic with either brodimoprim or trimethoprim indicated that only the combinations prevented recovery and regrowth of the cultures over 24 h. The ATP released from cultures of both strains of E. faecalis treated with brodimoprim and trimethoprim at the same concentrations was approximately 1.5 times greater with brodimoprim than with trimethoprim. Combinations of 3/4 of the MIC of each of the antibiotics in combination with 3/4 of the MIC of brodimoprim against cultures of both strains of E. faecalis resulted in greater release of ATP than occurred with equivalent trimethoprim combinations. It is postulated that the increased activities observed with the brodimoprim combinations resulted from an effect of brodimoprim on the bacterial cell permeability control. These results indicate that both brodimoprim and trimethoprim offer potential benefits for use with either carbenicillin, gentamicin, ciprofloxacin or rifampicin for the treatment of E. faecalis infections.

Production and Toxicity Assessment of Sophorosides from Torulopsis bombicola

Production of sophorosides from Torulopsis bombicola cultivated on three different substrates (methyl oleate, olive oil, and rapeseed oil) was studied. The higher yield (60-70%) was obtained with olive oil, which also corresponds to the less expensive lipid source. Sophorosides did not show great antifungal and antibacterial activities except against Candida parapsilosis and Staphylococcus aureus. Other tested microorganisms were resistant to and sometimes stimulated by these compounds. Cytotoricity of sophorosides on cultured human fibroblasts (human skin or MRC5 line) was almost the same as with cholesterol acetate but higher than with DL-α-lecithin

Viability of Bacteria in Glycerin and Ethanol Preserved Sclera

Sclera is commonly preserved in glycerin or ethanol before being used for ophthalmic surgery. The purpose of this study was to determine the ability of bacteria to survive in sclera preserved in glycerin or ethanol. Fresh sclera was inoculated with Staphylococcus aureus, Streptococcus pneumoniae, or Pseudomonas aeruginosa and transferred to preservative vials containing glycerin, 95% ethanol, or trypticase soy broth (control) and stored at room temperature. Pieces of sclera were removed from preservative at designated intervals over a 14-day period. The sclera was then homogenized, plated on blood agar, and incubated at 37 degrees C. Colonies were counted at 24, 48, and 72 hours. S. pneumoniae, P. aeruginosa, and S. aureus were recovered from glycerin preserved sclera for up to 12 hours, 1.5 days, and 8 days, respectively. No bacteria was recovered from the ethanol preserved sclera. Bacteria cannot be recovered from ethanol preserved sclera but can survive in glycerin preserved sclera for at least 8 days. Ethanol may offer advantages over glycerin as a scleral preservative due to its greater antibacterial activity.

Bacteriocins of Lactic Acid Bacteria in Combination Have Greater Antibacterial Activity

Antibacterial efficiency of two bacteriocins from lactic acid bacteria, pediocin AcH, and nisin was tested individually and in combination against several gram-positive bacterial strains including some involved in food spoilage and foodborne diseases. Pediocin AcH and nisin were more antibacterial in combination than when they were used alone. The principles of this greater antibacterial spectrum have been proposed. Bacteriocins in combinations can be used advantageously to design efficient natural food biopreservative(s).

The new fluorinated quinolones for antimicrobial prophylaxis in neutropenic cancer patients

Fluoroquinolones are the most attractive agents for prophylactic use in neutropenic cancer patients, due to their broad antimicrobial spectrum, high concentration in the faeces, systemic bactericidal activity, uncommon emergence of resistant strains and good tolerability. They have proved to be more effective than placebo, oral non-absorbable antibiotics or cotrimoxazole in the prevention of Gram-negative infections. In a prospective, randomised multicentre study performed by the GIMEMA infection program, ciprofloxacin was demonstrated to be more effective than norfloxacin for the reduction of febrile episodes, use of systemic antibiotics, and Gram-negative infections in neutropenic patients with haematological malignancies. The greater efficacy may be related to its better systemic or greater antibacterial activity. The potential problems related to the prophylactic use of fluoroquinolones are the increasing prevalence of Gram-positive infections caused by streptococci and coagulase-negative staphylococci; the reported emergence and nosocomial spread of resistant strains, especially among coagulase-negative staphylococci; the lack of their usefulness as empirical therapy in febrile neutropenic patients. Fluoroquinolones are today the better choice for preventing Gram-negative infections in neutropenic patients and ciprofloxacin should probably be preferred. More information on their efficacy and their relationship to the overall susceptibility of micro-organisms in patients with cancer would be valuable, and careful monitoring of patients treated with these drugs is therefore warranted.

Production of gliotoxin by Gliocladium virens as a function of source and concentration of carbon and nitrogen

Sources of carbon and nitrogen and the carbon:nitrogen (C:N) ratio influenced both production of gliotoxin and growth by a strain of Gliocladium virens . Higher antibacterial activity against Bacillus cereus was expressed in a defined medium amended with glucose and phenylalanine as the sources of carbon and nitrogen, respectively, than with other carbon and nitrogen sources tested. Gliotoxin extracted from the 6-day-old culture filtrate of the fungus and diluted by a factor of ten had greater antibacterial activity than four other unidentified antibacterial substances extracted from the same culture filtrate. Dynamics of mycelial growth and gliotoxin production were consistent over a range of C:N ratios (18:1, 31:1, and 42:1). Overall, as the mycelial weight of the fungus increased, the amount of gliotoxin increased up to 140 mg litre −1 of medium after 8–10 days of incubation. The rate of gliotoxin production (mg ml −1 ) was slower when the fungus was grown in a C:N ratio of 80:1 than in the other C:N ratios tested. Similar results were obtained when gliotoxin was recorded as mg gliotoxin per unit of mycelial weight. Maximum gliotoxin (140 mg l −1 ) was produced after eight days at all C:N ratios tested, except 80:1 for which ten days were required to produce this level of gliotoxin. The composition of the medium yielding maximum gliotoxin after eight days incubation consisted of 25 g glucose, 5·0 g phenylalanine, 2·0 g KH 2 PO 4 , 1·0 g MgSO 4 · 7H 2 O, 0·01 g FeSO 4 · 7H 2 O in 1·0 litre distrilled water, adjusted to pH 3·5 with 25% phosphoric acid.

The role of Gram-positive therapy in the neutropenic patient

The increasing prevalence of Gram-positive infections in neutropenic cancer patients seems to be related to the use of central venous catheters, chemotherapy-induced oral and gastrointestinal mucositis, and the prophylactic use of fluoroquinolones. The need for anti-Gram-positive therapy in the neutropenic patient is supported by the increasing prevalence and the changing resistance of Gram-positive pathogens, as well as by the poor response of Gram-positive bacteraemia to aminoglycoside plus beta-lactam regimens. Combined therapy with either vancomycin or teicoplanin and other empirical antibiotics, has proved efficacious in adults and children with neutropenia, fever and Gram-positive infection. Vancomycin exerts greater antibacterial activity against strains of coagulase-negative staphylococci than teicoplanin and there is more data on its routine clinical use. In its favour, teicoplanin is less toxic and easier to administer. The time when a glycopeptide antibiotic should be introduced is still a matter of debate; support for both initial therapy and subsequent rescue therapy is found in the current literature. Large clinical trials are warranted to clarify further the role of anti-Gram-positive therapy in the neutropenic patient.

The clinical development of mupirocin

Mupirocin is a novel antibiotic totally unrelated in chemical structure and mode of action to any other clinically useful class of antibiotics. It has greatest antibacterial activity against aerobic gram-positive cocci, namely, Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pyogenes, and other beta-hemolytic streptococci. Bactroban ointment is formulated as 2% mupirocin in polyethylene glycol ointment. No systemic absorption of mupirocin or its major metabolite, monic acid, has been detected in short courses of topical administration to healthy volunteers or to patients with epidermolysis bullosa after prolonged courses of therapy with Bactroban ointment. Randomized, multicenter, double-blind, vehicle-controlled clinical trials have shown that mupirocin is safe and effective for the treatment of impetigo.

Superior antibacterial action and reduced incidence of bacterial resistance in minocycline compared to tetracycline-treated acne patients

Twenty-five previously untreated acne patients were monitored throughout a 6-month course of therapy with either tetracycline or minocycline for changes in the numbers of staphylococci, propionibacteria and yeasts of the genus Malessezia on the skin surface. Antibiotic resistant staphylococci and propionibacteria were also counted. Minocycline (50 mg b.d.) produced a 10-fold greater reduction in propionibacterial numbers compared to tetracycline (500 mg b.d.) after 12 (P less than 0.02, t-test) and 24 weeks (P less than 0.05) of therapy. As treatment progressed, propionibacteria were replaced by yeasts, numbers of which were significantly increased by week 12 (P less than 0.02) in tetracycline-treated patients and by week 24 (P less than 0.01) in minocycline-treated patients. This suggests that yeasts have no role in the pathogenesis of acne but may compete with propionibacteria for the same niche. Overgrowth of antibiotic resistant staphylococci prevented any decrease in staphylococcal numbers in tetracycline-treated patients, but minocycline produced a significant and sustained reduction in staphylococcal numbers after 1 week of therapy (P less than 0.001). An increase in the number of multiply resistant (greater than or equal to 3 resistances) staphylococci occurred in 67% of tetracycline-treated and 33% of minocycline-treated patients by the end of the treatment period. There was no evidence of propionibacterial resistance in either treatment group. This study shows that minocycline has much greater antibacterial activity in vivo against both staphylococci and propionibacteria and produces less staphylococcal antibiotic resistance than tetracycline.

The modified model cavity method for assessing antibacterial properties of dental restorative materials.

A new in vitro method for assessing the antibacterial properties of dental restorative materials is described with ratios of test material/culture medium volume aiming to simulate conditions around a restoration in vivo. Antibacterial activity is determined by the reduction in optical density of the test culture relative to controls. The method was used for assessment of the antibacterial activity of five dental materials of different composition against five oral bacteria. Release of zinc and fluoride from these materials was also measured and correlated with antibacterial activity. There was a general trend toward greater antibacterial activity with increased zinc release, while fluoride release had a significant effect on only one organism. While all the materials, when freshly mixed, were strongly toxic to three out of the five bacteria studied, much of this activity was lost after the materials had set.

Effect of chlorine substitution on the structure and activity of 4-phenylthiosemicarbazide: crystal and molecular structure of 4-(4-chlorophenyl)thiosemicarbazide

The crystal structure of 4-(4-chlorophenyl)thiosemicarbazide has been determined by direct methods. This p-chloro-substituted 4-phenylthiosemicarbazide, with greater antibacterial activity than its unsubstituted precursor, crystallises in the space group P21/c with a= 14.594(4), b= 10.495(5), c= 12.384(4)A, β= 104.73(2)°, Z= 8, Dc= 1.469 g cm–3, and µ(Mo-Kα)= 5.83 cm–1. The structure has been refined using 1 967 reflections with I 3σ(I). The antibacterial activity of both the present compound and its precursor has been attributed to electron delocalisatoin in the thiosemicarbazide moiety enhancing both its donor and reductive capacities.

Antibacterial Activity of Bovine Blood Neutrophils and Their Cationic Proteins

Six cationic protein bands were identified in extracts of both normal bovine blood neutrophils and their granules subjected to polyacrylamide disc gel electrophoresis. Band 1, the most cationic protein, was as positively charged as crystalline egg white lysozyme, and band 2 was as positively charged as ribonuclease.Antibacterial activity of various leukocyte fractions and cationic proteins was determined in vitro for Enterobacter aerogenes strain 2412-2. Antibacterial activity of various preparations was proportional to amount of test material present and varied inversely with number of bacteria in the test system. Comparative evaluations revealed that the neutrophil granule fraction had greater anti-bacterial activity than the whole cell homogenate or individual cationic proteins. Among cationic proteins, band 1 had the highest antibacterial activity, band 2 had the lowest, and band 3 had intermediate antibacterial activity. Cationic protein bands 4, 5, and 6 exhibited growth stimulatory rather than a growth inhibitory activity.

Moxalactam: the first of a new class of beta-lactam antibiotics.

Moxalactam is the first member of a new class of beta-lactam antibiotics to be evaluated clinically. Although structurally related to cephalosporins, moxalactam has an oxygen atom where the cephalosporin nucleus has a sulfur atom. The substitution of oxygen for sulfur in moxalactam provides it with greater antibacterial activity than that of its cephalosporin analog. Moxalactam has three other structural elements that affect biologic activity: the methyltetrazolethio moiety, which maximizes in vitro activity; the 7-alpha-methoxy substituent, which confers beta-lactamase stability; and the p-hydroxyphenylmalonyl group, which positively influences not only beta-lactamase stability and the antibacterial spectrum of moxalactam, but also its pharmacokinetics, and leads to a long half-life without high serum binding.

The relationship of amniotic fluid phosphate-to-zinc ratios to post-cesarean section infection

Although many reports concerning risk factors for post-cesarean section febrile morbidity have been published, few have considered the antibacterial activity of amniotic fluid. This study, in which the amniotic fluid phosphate-to-zinc ratios were used as a reflection of antibacterial activity, demonstrates that, among 85 patients who underwent elective repeat cesarean sections, less febrile morbidity was present when the patient's amniotic fluid had greater antibacterial activity. There was less standard fever, use of antibiotics, and endometritis among patients whose amniotic fluid had lower phosphate-to-zinc ratios.

Efficacy of two trimethoprim-sulphonamide combinations in experimental pyelonephritis in the rat

Co-trimazine, a new combination of trimethoprim and sulphadiazine intended for treatment of urinary tract infections, was tested and compared to co-trimoxazole in an experimental model of acute, obstructive pyelonephritis in the rat. The tests were carried out at four dose levels corresponding to the clinically recommended doses and to 1/4, 1/2, and 3/4 of the latter. The drugs were administered orally. Co-trimazine was found to have a greater antibacterial activity than co-trimoxazole and its use at a lower dosage than that of the latter appears warranted.

Minocycline

Minocycline (Minocin - Lederle) is a long-acting tetracycline. The main advantages claimed for minocycline by the manufacturer are that it is active against many strains of Staphylococcus aureus that are resistant to other tetracyclines, that it is more active than tetracycline against respiratory pathogens, and that it is useful in the treatment of the meningococcal carrier state. How important clinically is the greater antibacterial activity of minocycline compared with other tetracyclines? And how frequent and how serious are the vestibular effects of the drug?