Antibacterial activity of Thonningia sanguinea against some multi-drug resistant strains of Salmonella enterica

Background: The emergence of strains of S.enterica with multiple drug resistance (MDR) is of great concern worldwide.The extracts of flowers of Thonningia sanguinea are used in traditional medicine in Ivory Coast to treat diarrhoeal diseases including salmonellosis. Previous studies had shown inhibition of the MDR strain Salmonella Enteritidis lysotype 6. Objectives: The present study focused to investigate the effect of the extract of the flowers of Thonningia sanguinea on some clinical MDR strains of Salmonella namely S. Tyhpi, S. Typhimurium, S. Hadar and a sensitive strain (S. Enteritidis). Methods: The antimicrobial parameters were determined by double dilution with agar slant method. This method led us to determine MIC, IC(50) and MBC. Results: The MDR strain of S.Typhimurium presented the highest MIC (2.5 mg/ml) whereas the other two MDR strains (S. Hadar, S. Typhi) and the sensitive one (S. Enteritidis) had the same MIC (1.25 mg/ml). The four strains presented the same MBC (2.5 mg/ml). The MDR strain of S. Typhi is the most susceptible strain to the aqueous extract of the flowers of Thonningia sanguinea according to The IC(50) values. Conclusions: The aqueous extract of Thonningia sanguinea can provide an alternative therapy for the treatment of salmonellosis, mainly for typhoid fever caused by MDR strains of S Typhi. The extract also inhibits S.Hadar a MDR emerging strain in Ivory Coast.     

Comparative study of the antibacterial activity of cefpodoxime against enterobacteria producing beta lactamases

Cefpodoxime proxetil (RU 51 807) is the oral prodrug of cefpodoxime (RU 51 763), a third generation cephalosporin. The antibacterial activity of cefpodoxime was compared with the activities of amoxicillin in combination with clavulanic acid (AUG), cefaclor (CCl), cefuroxime (CXM) and cefotaxime (CTX), against species of Enterobacteriaceae showing a resistance pattern against ampicillin (AMP), ticarcillin (TIC), cefalothin (CFT) and cefotaxime (CTX) respectively. For strains AMP and TIC R, CFT and CTX S, MICs 90% of cefpodoxime were 1 mg/l (E. coli), 0.5 (K. pneumoniae), 0.06 (P. mirabilis), 0.5 (Shigella sp.) and 1 (Salmonella sp.); they were 4 to 16 times as high for AUG -CCL -CXM and 4 to 16 times as low for CTX. For K. pneumoniae AMP and TIC R, CFT I/R and CTX S, similar résults were obsereved for the 5 beta-lactam antibiotics, but with an activity 10 times as low. Among the species AMP R, TIC S, CFT R and CTX S, cefpodoxime was active against P. rettgeri, P. stuartii, C. diversus, E. aerogenes and Y. enterocolitica (MICs 90% ranging from 2 to 4 mg/l; from 0.12 to 1 mg/l for CTX) and less active or inactive against P. vulgaris, E. cloacae, S. marcescens, M. morganii and E. coli (MICs 90% ranged from 16 to 32 mg/l; from 1 to 4 mg/l for CTX).(ABSTRACT TRUNCATED AT 250 WORDS)     

Antibacterial activity of three Leuconostoc strains isolated from vacuum-packaged processed meats

One hundred and fifty lactic acid bacteria (LAB) isolated from vacuum-packaged processed meats were screened for antagonistic activity against various food spoilage microorganisms and foodborne pathogens. Nineteen strains produced bacteriocins active against closely related LAB and Listeria strains. Leuconostoc carnosum (LA54a and TA26b) and Leuconostoc mesenteroides subspecies dextrancum (TA33a) produced bacteriocins that were susceptible to proteolytic enzymes, but not to catalase, lysozyme or chloroform. They were heat stable up to 100 °C for thirty minutes at pH 2 to 7, and exerted a bacteriolytic effect. Bacteriocin production by all Leuconostoc strains was growth associated, occurring at incubation temperatures of 0 °C to 30 °C and initial medium pH 4.5 to 7.5. Probing of plasmid DNA from the three Leuconostoc strains with an oligonucleotide probe homologous to the nucleotide sequence of leucocin A-UAL 187 indicated plasmid-mediated bacteriocin production. Homology of the three Leuconostoc bacteriocin-coding genes to the amino-terminal end of the leucocin A-UAL 187 gene from Leuconostoc gelidum UAL 187 is therefore suggested. This evidence implies that all three Leuconostoc strains produce type 2, Listeria active bacteriocins.     

Antibacterial activity of rare Streptomyces species against clinical resistant bacteria

In the search for new antibiotics from Steptomyces, investigating extremes habitats enhances the probability of isolating novel producers. In this context, the antibacterial activity of four Streptomyces strains isolated from Ezzmoul saltpans was studied. Two of them showed antibacterial activity against antibiotic's resistant bacteria (Bacillus cereus: β-lactamines and sulfamides resistant, Streptococcus faecalis: penicillin, tetracycline and cotrimoxazole resistant, and Staphylococcus aureus Mu 50: vancomycine resistant). The most active Streptomyces strain produces one type of polar bioactive molecules that resists to temperature variation and light exposition. Its activity appears in the first culture day and reaches its maximal value in the fourth day. The second strain presents themoresistant activity that reaches its maximal value in the first culture day. It produces two types of bioactive molecules, one is polar and the second is non polar (according to thin layer chromatography technique results).     

Antibacterial activity of particulate bioglass against supra- and subgingival bacteria

Particulate Bioglass is a bioactive material used in the repair of periodontal defects. This material undergoes a series of surface reactions in an aqueous environment which lead to osseointegration. The aim of this study was to determine whether these reactions exerted an antibacterial effect on a range of oral bacteria. Streptococcus sanguis, Streptococcus mutans and Actinomyces viscosus were suspended in nutrient broth (NB), artificial saliva (AS) or Dulbecco's modified eagle medium plus 10% foetal calf serum (DMEM + 10%FCS), with or without particulate Bioglass. All bacteria showed reduced viability following exposure to Bioglass in all the media after 1 h. This antibacterial effect increased after 3 h. Porphyromonas gingivalis, Fusobacterium nucleatum, Prevotella intermedia and Actinobacillus actinomycetemcomitans were suspended in either BM broth or 40% horse serum (HS) in RPMI. A considerable reduction in viability was observed with all bacteria tested, in both media, compared to inert glass controls. In further experiments it was found that the viability of S. sanguis was significantly reduced following exposure to NB pre-incubated with Bioglass. Additionally, it was found that neutralisation of this highly alkaline solution eliminated the antibacterial effect. Moreover, a solution of NB and NaOH (of equivalent pH) exerted an antibacterial effect of similar magnitude to that of the solution pre-incubated with Bioglass. Thus, particulate Bioglass exerts an antibacterial effect on certain oral bacteria, possibly by virtue of the alkaline nature of its surface reactions. This may reduce bacterial colonisation of its surface in vivo.     

Antibacterial activity of Hibiscus rosa-sinensis L. red flower against antibiotic-resistant strains of Helicobacter pylori and identification of the flower constituents

Utilization of plant resources for treatment of Helicobacter pylori infections is one of the appealing approaches as rapid emergence of antibiotic-resistant strains is occurring throughout the world. Ethanol extract and its fractions from Hibiscus rosa-sinensis red flower were assessed for antibacterial and urease inhibitory activities towards forty-three clinical strains and two reference strains of H. pylori. The ethyl acetate fraction exhibited the most potent bacteriostatic activity with minimum inhibitory concentrations (MICs) of 0.2-0.25 mg/mL and minimum bactericidal concentrations (MBCs) of 1.25-1.5 mg/mL against all test strains, including forty-three strains resistant to one to four antibiotics, azithromycin (MICs, 8-256 µg/mL), erythromycin (MICs, 8-128 µg/mL), levofloxacin (MICs, 8-256 µg/mL), and/or metronidazole (MICs, 8-256 µg/mL). The fraction had similar antibacterial activities toward these test strains suggesting the preparation and the antibiotics do not have a common mechanism of anti-H. pylori activity. The fraction also had stronger effects on biofilm formation, morphological conversion, and urease activity of H. pylori than the other fractions and the ethanol extract. These flower preparations were non-toxic to three human cell lines, and nine compounds were also isolated and identified from the ethyl acetate fraction. In vivo research needs to be conducted to confirm the potential usefulness of H. rosa-sinensis flower and its constituents for effective prevention and treatment of H. pylori disease.     

Antibacterial activity and mechanism of berberine against Streptococcus agalactiae

The antibacterial activity and mechanism of berberine against Streptococcus agalactiae were investigated in this study by analyzing the growth, morphology and protein of the S. agalactiae cells treated with berberine. The antibacterial susceptibility test result indicated minimum inhibition concentration (MIC) of berberine against Streptococcus agalactiae was 78 μg/mL and the time-kill curves showed the correlation of concentration-time. After the bacteria was exposed to 78 μg/mL berberine, the fragmentary cell membrane and cells unequal division were observed by the transmission electron microscopy (TEM), indicating the bacterial cells were severely damaged. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) study demonstrated that berberine could damage bacterial cells through destroying cellular proteins. Meanwhile, Fluorescence microscope revealed that berberine could affect the synthesis of DNA. In conclusion, these results strongly suggested that berberine may damage the structure of bacterial cell membrane and inhibit synthesis of protein and DNA, which cause Streptococcus agalactiae bacteria to die eventually.     

Impaired bactericidal activity of cord sera against Salmonella strains

Weaker bactericidal activity of cord sera against Salmonella bacilli was shown in comparison with maternal venous sera. No correlation was found between the bactericidal activity and the levels of complement, immunoglobulins and lysozyme in cord sera. Worthy of notice is detected in these researches specificity of bactericidal action of cord sera.     

Antibacterial activity of norfloxacin against bacterial isolates from the urinary tract

Two hundred fourteen isolates from clinical specimens were tested in vitro to determine their susceptibility pattern against norfloxacin. Of the 151 strains of gram-negative bacteria tested, 149 (98.7%) were susceptible. Sixty-three (100%) of the gram-positive bacteria tested were also susceptible to norfloxacin. Norfloxacin showed excellent activity against all bacteria isolated from urine.     

Pharmacokinetics of apalcillin in pediatrics

Apalcillin is a semi-synthetic broad-spectrum penicillin which is particularly active against Pseudomonas. Pharmacokinetic studies were carried out after slow (3 mn) intravenous administration of a single dose of 20 or 30 mg/kg in five categories of infants: premature, dysmature, full term newborn up to 8 days of age, infant aged 8 days to 1 month and infant beyond 1 month. Elimination half-lives in these five groups are respectively: 6.83, 5.44, 5.01, 2.28 and 1.28 hours. A decrease in elimination half-life and increase in total clearance are observed as the infant matures. Renal clearance represents a quarter of total clearance suggesting than there is considerable extrarenal clearance. Pharmacokinetic findings beyond one month of age are comparable to those demonstrated in adults. The dysmature infant is characterized by a significantly lower steady-state distribution volume (p less than or equal to 0.025) as compared to the full term neonate. From these results the recommended dosage is: 20 mg/kg twice daily for premature, dysmature and full term neonates up to 8 days, 30 mg/kg twice daily for infants from 8 days to one month of age, and 30 mg/kg three or four times a day for infants above one month of age.     

Comparative bacteriostatic activity of 10 cephalosporins against 100 strains of Serratia

The in vitro activity of 10 cephalosporins was evaluated against 100 different clinical isolates of Serratia. 90% of these strains were inhibited at the following concentrations (microgram/ml): ceftazidime = 0.5; ceftriaxon = 0.9; cefmenoxime = 1; lamoxactam = 1.1; cefotaxime = 1.25; cefotetan = 2; cefoperazone = 28; cefoxitine = 64; cefotiam = 80; ceforanide greater than 512. Ceftazidime was the most potent agent. Ceftriaxon, cefmenoxime, lamoxactam and cefotaxime had also a very high activity. All the strains were clinically susceptible to these 5 cephalosporins (MIC less than or equal to 16). The other cephalosporins were less active.     

Pharmacokinetic study of apalcillin after infusion

Apalcillin is a new semi-synthetic penicillin of the uridino-penicillin group. The study comprises two groups of 6 subjects receiving 1 g and 2 g respectively of apalcilline by a two-hour infusion. The assays done by HPLC and microbiology show a good correlation between the two methods. The serum concentrations at the end of the infusion are: 32,2 micrograms/ml-1 (1 g) and 62,7 micrograms/ml-1 (2 g). The modelisation of the serum curves has been realized according to an open model with two compartments. A phase of rapid distribution is observed: t 1/2 alpha of 19.5 mn (1 g), 8.96 mn (2 g) followed by a phase of longer elimination: t 1/2 beta of 1.17 h (1 g), 1.15 h (2 g). The distribution volume at the steady-state is: 14.19 l (1 g), 14.76 l (2 g). This volume, much greater than the plasmatic volume, allows to suppose a good tissular diffusion of apalcilline. The urinary concentrations of the twelve first hours are: 182.64 micrograms/ml (1 g), 323 micrograms/ml (2 g). The urinary elimination during the 24 hours following the administration is: 18.58% (1 g), 16.47% (2 g).     

Antibacterial activity of dental composites containing quaternary ammonium polyethylenimine nanoparticles against Streptococcus mutans

The antibacterial activity of quaternary ammonium polyethylenimine (PEI) nanoparticles embedded at 1%w/w with clinically used bonding, flowable and hybrid dental composite resins and cured by light polymerization was studied. The antibacterial activity was tested with Streptoccocus mutans by: (i) the agar diffusion test (ADT); (ii) the direct contact test; (iii) bacterial growth in the materials elute; (iv) and scanning electron microscope (SEM). Using the direct contact test, antibacterial activity (p<0.001) was found in all three types of composite resins incorporated with the synthesized nanoparticles. The effect lasted for at least 1 month. SEM demonstrated bacterial debris and no streptococcal chains at 24h of bacterial contact. The addition of 1%w/w of nanoparticles did not affect the flexural modulus and the flexural strength of the dental composite materials.The results indicate that quaternary ammonium PEI nanoparticles immobilized in resin-based materials have a strong antibacterial activity upon contact without leach-out of the nanoparticles and without compromise in mechanical properties.     

Bactericidal activity of disinfectants against certain bacterial strains. Klebsiella pneumonia

Twenty disinfectants were tested against a strain of K. pneumoniae. A suspension test with incremental addition of microorganisms was used. The influence of interfering substances (proteins and hard water) on the activity of disinfectants was also determined. Iodine compounds were influenced by proteins in distilled and hard water. The presence of mineral ions inactivated the polyvinylpyrrolidone-iodine 10% and chloroxylenol preparations against K. pneumoniae. The activity of some iodine products disappeared at the second and third incremental addition of microorganisms; the chloroxylenol and the phenolic compounds were inactivated by proteins at the third incremental addition. The sensibility of K. pneumoniae to the other disinfectants was not influenced by proteins, ions and incremental bacterial additions.     

Antibacterial activity of Wratizolin

Wratizolin in the concentration of 1-10 micrograms/ml was found to inhibit the growth of Gram-positive bacteria such as: Staphylococcus, Streptococcus, Sarcina, Corynebacterium, and some representatives of aerobic bacilli. Gram-negative bacteria of Enterobacteriaceae and Pseudomonas were not sensitive to Wratizolin even in the concentration of 100 micrograms/ml.