Antimicrobial effect of crude extracts of Nigella sativa on multiple antibiotics-resistant bacteria

Different crude extracts of Nigella sativa were tested for antimicrobial effectiveness against different bacterial isolates. These isolates comprised 16 gramnegative and 6 grampositive representatives. They showed multiple resistance against antibiotics, specially the gramnegative ones. Crude extracts of Nigella saliva showed a promising effect against some of the test organisms. The most effective extracts were the crude alkaloid and water extracts. Gramnegative isolates were affected more than the grampositive ones.     

Antibacterial spectrum of lisosubtilin G10X

Data on the antibacterial spectrum of lysosubtilin G10X, a preparation of lytic enzymes from Bacillus subtilis SK-52 are presented. Lysosubtilin was active against grampositive and gramnegative pathogenic bacteria. When it was used as a substrate of live lyophilized microbial cells the highest lysis levels were observed in B. brevis, B. cereus, B. pumilis, B. subtilis and S. faecalis. Preincubation of the substrate in acid media mainly increased the levels of the lysis by enzyme preparation. Sometimes the increase was very high (B. sphaericus, B. subtilis 720, E. coli K12 and MRE-600). Such a preincubation provided cell lysis in some strains not liable to the effect of lysosubtilin (B. cereus 1312, C. renale, M. luteus, S. aureus KP, 800, 805 and 126001, S. pyogenes 291). An increase in the lysosubtilin concentration in the reaction mixture in the majority of the cases did not provide favourable results. However, some strains resistant to the preparation at a concentration of 1000 units/ml were lysed with its 10 times higher doses. An increase in the lysis level was also achieved with increasing the time of the incubation with the enzyme preparation. Proceeding from the preparation antibacterial spectrum it is possible to recommend it for treatment of diseases in agricultural animals. Its use in veterinary was a success.     

Antibiotic susceptibility of isolates from blood of patients in intensive care units of emergency medical service

The microbiological tests of 769 blood samples from 220 patients, treated in 4 intensive care units of the N.V. Sklifosovsky Research Institute for Emergency Medical Service within a period from January 2009 to June 2010, were analysed. Etiologically significant microorganisms were detected in 323 samples (42%). 253 isolates were used in the analysis. Grampositive and gramnegative pathogens were detected in 47 and 42% of the cases respectively. Candida and anaerobic organisms were isolated in 8 and 3% of the cases respectively. Staphylococcus aureus and enterococci were isolated in 24 and 15% of the cases respectively. Nonfermenting gramnegative bacteria and enterobacteria were revealed in 25 and 17% of the cases respectively. Differences in the spectrum of the sepsis pathogens depending on the patients contingent were shown. The maximum summary susceptibility of the grampositive cocci was observed with respect to vancomycin and linezolid and that of the gramnegative bacteria was stated with respect to imipenem and meropenem.     

Impact of exogenic proteolytic enzymes on bacteria]

The impact of papain, trypsin and the enzyme complex vobenzyme on formation of biofilms by grampositive and gramnegative bacteria was studied. The enzymes were shown to inhibit the biofilm formation. When applilied to the formed associations, the enzymes potentiated the effect of antibiotics on the bacteria located in them. An increase in the antimicrobial effect of various nonrelated antibiotics was not connected with a change in the bacteria susceptibility but likely resulted from higher bioavailability of the drugs in the presence of the enzymes.     

Antibiotic properties of the strains of the basidiomycete Lentinus edodes (Berk.) sing]

Antibiotic properties of the extracts from the fermentation broth and mycelium of 15 strains of the edible and medicinal basidiomycete L. edodes were studied and it was shown that the extracts were active against grampositive and gramnegative bacteria, yeasts and mycelial fungi, including dermatophytes and phytopathogens. The strains differed by the set of the organisms susceptible to the action of the extracts. Strains of L. edodes combining marked antibiotic properties and high yields of water soluble polysaccharides were screened. The active compounds were detected by preparative TLC. Two of them were identified with UV- and mass spectrometry as lentinamycin B and erytadenine (lentinacin). Lentinamycin B was found to be the main component responsible for the antibiotic activity of the L. edodes strains.     

Microbiological and biochemical indices of changes in microbial ecology of rat large intestine under the effect of rifampicin

Intragastric administration of rifampicin to rats in a dose of 40 mg/kg resulted in decreasing of the contents of grampositive cocci and lactobacilli and increasing of the number of gramnegative aerobic potentially pathogenic bacteria in feces of the experimental animals. It was noted that along with changes in the composition of the fecal microflora after the exposure to the antibiotic there were disorders in feces excretion of ammonia and amino acids such as alanine and glutamic acid as well as lactic, amber, butyric, valeric and alpha-ketoglutaric acids. Reduction of the changed biochemical indices was shown to be slower than that of the routine microbiological indices.     

Combined action of antibiotics and deoxyribonuclease on bacteria]

The impact of DNase on formation of biofilms by grampositive and gramnegative bacteria was studied. The enzyme was shown to inhibit the biofilm formation and have no toxicity to bacteria. When applied to the formed associations, DNase potentiated the effect of antibiotics on the bacteria located in them. An increase in the antimicrobial effect of various nonrelated antibiotics was not connected with a change in the bacteria susceptibility but likely resulted from a break of the genetic cooperation of the cells' community, connected with functions of extracellular DNA of the biofilm's matrix.     

Characteristics of azithromycin action on bacterial biofilms of pneumonia pathogens]

Azithromycin (Zitrolid) action on biofilms formed by gramnegative and grampositive microorganisms, isolated from patients with respiratory tract infections was investigated. The drug was effective at the stage of the biofilm formation and on exposition to the already formed biofilms.     

Effectiveness of gentamicin sulfate in suppurative-inflammatory processes of varying localization]

Antibiotic sensitivity of 486 strains of grampositive and gramnegative organisms isolated from patients with purulent infections was studied in vitro. Gentamicin was shown to be highly active as compared to kanamycin and other antibiotics against the main causative agents of purulent inflammatory infections including multiresistant E. coli, Proteus, Ps. aeruginosa, Staphylococcus. High efficiency of gentamicin in therapy of peritonitis, septic conditions, purulent postoperative wounds, infections of the urinary tract, pneumonia, etc. (197 patients) was shown. Positive results were obtained in 87.4 per cent of the cases. Side effects, such as albuminuria, hyperthermic reaction, rash, pruritis were registered in 3 per cent of the patients.     

Staphylococcal Bacteriophage-Associated Lysin: a Lytic Agent Active Against Staphylococcus aureus

A lytic enzyme active against viable, intact staphylococci is released into culture fluids upon lysis of bacteriophage-infected Staphylococcus aureus PS53 cells. This enzyme, staphylococcal phage-associated lysin (PAL), was partially purified by ammonium sulfate precipitation and gel filtration through Sephadex G-200. PAL is optimally active at pH 6.5 and 30 C, and lytic activity is greatly enhanced by the addition of reducing agents. Lytic activity was observed against all strains of staphylococci tested and against purified staphylococcal cell walls, but no activity was noted against other bacterial species. PAL possesses peptidase activity and results in the production of spheroplasts which can be osmotically stabilized for extended periods by the addition of 7.5% polyethylene glycol 4000.     

Optimization of tuberculosis complex chemotherapy with the use of moxifloxacin]

It was shown in vitro that moxifloxacin by its activity against Mycobacterium tuberculosis (susceptible and resistant to the main antituberculosis agents) was highly superior to lomefloxacin (by 2 to 4 times by the MIC and by 4 times by the MBC). In murine lung tissue culture the highest effect was observed with the use of moxifloxacin in combination with isoniazid and pirazinamide. The efficacy of the regimens with the use of moxifloxacin was estimated in the treatment of 152 patients with pulmonary tuberculosis diagnosticated for the first time. The use of moxifloxacin was shown to be most advantageous in complex therapy of patients with extended and progressive tuberculosis due to polyresistant Mycobacterium tuberculosis strains or patients with concomitant nonspecific inflammatory diseases of the respiratory tracts due to a great variety of grampositive and gramnegative organisms, acid fact bacteria, atypical bacteria and a great variety of anaerobes. The tolerance of the treatment regimens with the use of moxifloxacin was mainly satisfactory.     

Antibacterial activity of rifampicin against the causative agents of suppurative, septic diseases]

The antibacterial activity of rifampicin was studied in comparison with other antibiotics with respect to clinical strains isolated from cases with various purulent inflammatory processes caused by Staphylococcus, E. coli, Ps. aeruginose, Proteus. The aim of the study was to define the role of rifampicin in the treatment of the above infections. No rifampicin resistant strains were found among staphylococci belonging to the phenotype carrying the determinants of resistance to 2-8 antibiotics. Rifampicin was less active against gramnegative organisms. High heterogeneity of the microbial population of rifampicin was shown with respect to all microbial strains tested. The rate of the spontaneous mutants was high. The average rate of the mutants was 1-7.7-10-8. The studies on the dynamics of the rifampicin resistance increase in the strains of Staphylococci, E. Coli, Ps. aeruginosa and Proteus showed that the resistance increased after 1-2 passages, which means that one-stage mutation was characteristic rifampicin.     

Relationships Among Coagulase, Enterotoxin, and Heat-stable Deoxyribonuclease Production by Staphylococcus aureus

The relationship between heat-stable deoxyribonuclease and coagulase production was investigated in the interest of developing more rapid diagnostic and quantitative procedures for distinguishing toxigenic and pathogenic staphylococci from closely related saprophytic organisms.     

医院内感染的病原菌分布及其耐药谱的分析

本文统计了我院１９９２年８月—１９９４年７月两车间医院内感染病原菌的分离结果,分离出病原菌２５种７５８株,其中革兰氏阳性菌１６３株（占２１．５１％）,革兰氏阴性菌３７８株（占４９．８７％）,真菌２１７株（占２８．６２％）。院感病原菌依次为,白色念珠菌、绿脓假单胞菌表、葡菌、肺炎克雷伯氏菌、酵母菌及大肠艾希氏菌等,显示了真菌及表葡菌在院内感染中已经上升到不可忽略的地位。用１８种常用抗生素,对除真菌外的上述病原菌５４１株做耐药谱测定,并发现除了表葡菌及多数革兰氏阴性菌对喹谱酮类及少数头孢三代抗生素尚属敏感外,大部分均具有越来越广泛的耐药性。     

Increase in tetracycline activity by using surface-active substances]

The antimicrobial effect of cationic and anionic surface-active substances, i.e. catamine AB and sulphonol NP-3 respectively was studied in vitro with respect to gramnegative bacteria. In non-bactericidal concentrations catamine AB significantly increased the efficacy of tetracyclines, while the anionic compound had no such effect. The increase in the tetracycline activity was due to the antibiotic increased absorption (14C-oxytetracycline as an example) on the treatment of gramnegative bacteria with catamine AB and staphylococci with catamine AB and sulphonol NP-3, which was mainly associated with impairement of the cell membrane permeability by the surface-active substances.     

Antimicrobial action spectrum of triterpene and steroid glycosides]

Antimicrobial activity of 9 triterpene glycosides of the plant and animal origin was studied. It was found that saponins inhibited the fungal growth to different extents and had no activity against grampositive and gramnegative bacteria. Triterpene glycosides of the animal origin, i.e. holoturins A and B, stichoposids A and C had the most pronounced antifungal activity as compared to the saponins isolated from plants. Changes in the length of the carbon chain from 2 to 6 monosugars had no significant effect on the activity of the triterpeneglycosides studied.     

Lytic Action of Inducible Bacteriocin Clostocin O

Clostocin O had a remarkable lytic action toward the exponentially growing organisms of Clostridium saccharoperbutylacetonicum No. 8. The cellular lysis was inhibited by addition of heavy metal cations such as Cu²⁺, Ni²⁺, and Cd²⁺, or fradiomycin and RNase, which had been reported to be the inhibitors for lytic enzymes such as some of clostridial phage-endolysin and clostocin O-endolysin. The formalin-treated organisms and antibiotic-treated organisms, of which autolysin activity was inhibited, were also lysed by clostocin O. The induced cellular lysis by clostocin O was thought to be due to the lytic enzyme attached to clostocin O.     

Production and ecological significance of yeast cell wall-degrading enzymes from oerskovia

Motile actinomycetes capable of degrading walls of viable yeast cells were isolated from soil and identified as Oerskovia xanthineolytica. A lytic assay based on susceptibility of enzyme-treated cells to osmotic shock was developed, and 10 of 15 strains of O. xanthineolytica, Oerskovia turbata, and nonmotile Oerskovia- like organisms from other collections were found to possess yeast lytic activities. All lytic strains produced laminaranase and alpha-mannanase, but the amounts, determined by reducing group assays, were not proportional to the observed lytic activities. The Oerskovia isolates demonstrated chemotactic, predatory activity against various yeast strains and killed yeasts in mixed cultures. Of 15 carbon sources tested for production of lytic enzyme, purified yeast cell walls elicited the highest activity. Glucose repressed enzyme production and caused cells to remain in the microfilamentous and motile rod stages of the Oerskovia cell cycle. Crude lytic activity was optimal at pH 5.6 to 7.0 and inactivated by heating for 6 min at 50 degrees C. Partial purification by isoelectric focusing showed that all lytic activity was associated with four beta-(1-->3)-glucanases. The absence of protein disulfide reductase, N-acetyl-beta-d-hexosaminidase, and phosphomannanase in crude preparations indicated that the principal enzyme responsible for yeast wall lysis was a beta-(1-->3)-glucanase that produced relatively little reducing sugar from yeast glucan.     

Antimicrobial profile of ceftazidime: the situation in three larger hospitals in Prague between 1981 and 1983

As a part of preclinical trials of 2,996 clinical isolates from three larger hospitals in Prague were qualitatively and quantitatively assayed for in vitro sensitivity to ceftazidime. In gramnegative bacteria the incidence of resistance to ceftazidime in strain of Enterobacter, Serratia Proteus and Pseudomonas species ranged from 4% to 6% of strains. In grampositive bacteria only strains of enterococci, listeriae and anaerobic bacteria are excluded from the action of this broad-spectrum antibiotic. According to present experiences the antipseudomonal activity of ceftazidime is approximately the same as that of cefsulodine and cefoperazone. Alarmingly, one of the Pseudomonas aeruginosa isolates was found to show a distinct multiresistance to all available lactam, aminoglycoside and broad-spectrum antimicrobials, including ceftazidime.     

Electron Microscopy and Viability of Lysostaphin-induced Staphylococcal Spheroplasts, Protoplast-like Bodies, and Protoplasts

The cell walls of a selected isolate of Staphylococcus aureus FDA 209P were observed undergoing progressive disintegration when exposed to lysostaphin (1 unit/ml) in 24% NaCl solution. Electron micrographs of ultrathin sections of test cells after exposure to lysostaphin for 2 min showed only superficial evidence of lytic damage. However, an average of 89% of these cells were osmotically fragile, and 21% were damaged beyond their capacity to regenerate cell walls and to grow as normal staphylococci. The 68% (average) of the osmotically fragile cells which retained the capacity to revert to normal staphylococci were designated spheroplasts. Neither perforations of the cell walls nor separation of the cell walls from the plasma membranes were observed in the micrographs of these 2-min spheroplasts. Thus, it appears that the osmotic fragility of these and possibly all lysostaphin-induced staphylococcal spheroplasts results from the hydrolysis of a critical number of the pentapeptide cross-linkages of the murein of the cell wall. Electron micrographs of cells exposed to lysostaphin for 5 to 10 min showed perforations and more extensive damage, including the separation of walls from the plasma membranes and the disintegration of large sections of the walls. Smaller numbers of spheroplasts (21 and 8%) were recovered from these 5- and 10-min preparations; those recovered probably represent cells which were attacked more slowly than the majority by the lytic enzyme. The nonrevertible, osmotically fragile cells that retained segments of cell wall were designated protoplast-like bodies. After 20-min exposure to lysostaphin, all of the cell wall was digested away from most of the cells, and true staphylococcal protoplasts were produced. These lysostaphin-induced, osmotically fragile forms appear to have different osmotic properties from the staphylococcal "protoplasts" reported by other investigators and should serve as the basis for a variety of fundamental investigations.