Characterization of two bacteriophages specific to Acinetobacter baumannii and their effects on catheters biofilm.

Multidrug-resistant strains of Acinetobacter baumannii cause major nosocomial infections. Bacteriophages that are specific to the bacterial species and destroy bacteria can be effectively used for treatment. In this study, we characterized lytic bacteriophages specific to A. baumannii strains. We isolated lytic bacteriophages from environmental water samples and then investigated their morphology, host range, growth characteristics, stability, genome analysis, and biofilm destruction on the catheter surface. Our results showed that the efficacy of the phages varied between 32% and 78%, tested on 78 isolates of A. baumannii; 80 phages were isolated, and two lytic bacteriophages, vB_AbaP_HB01 (henceforth called C2 phage) and vB_AbaM_HB02 (henceforth called K3 phage), were selected for characterization. Electron microscopy scans revealed that the C2 and K3 phages were members of the Podoviridae and Myoviridae families, respectively. Whole-genome sequencing revealed that the sequence of the C2 phage is available in the NCBI database (accession number: OP917929.1), and it was found sequence identity with Acinetobacter phage AB1 18%, the K3 phage DNA sequence is closely related to Acinetobacter phage vB_AbaM_phiAbaA1 (94% similarity). The cocktail of C2 and K3 phages demonstrated a promising decrease in the bacterial cell counts of the biofilm after 4 h. Under a scanning electron microscope, the cocktail treatment destructed the biofilm on the catheter. We propose that the phage cocktail could be a strong alternative to antibiotics to control the A. baumannii biofilm in catheter infections.

The effect of phage-antibiotic combination strategy on multidrug-resistant Acinetobacter baumannii biofilms.

Acinetobacter baumannii (A. baumannii) is considered a critical human pathogen due to multi-drug resistance and increased infections. As a result of the resistance of A. baumannii biofilms to antimicrobial agents, it is necessary to develop new biofilm control strategies. In the present study, we evaluated the efficacy of two previously isolated bacteriophage C2 phage, K3 phage and phage cocktail (C2 + K3 phage) as a therapeutic agent in combination with antibiotic (colistin) against biofilm of multidrug-resistant A. baumannii strains (n = 24). The effects of phage and antibiotics on mature biofilm were investigated simultaneously and sequentially in 24 and 48 h. The combination protocol was more effective than antibiotics alone in 54.16% of the strains in 24 h. The sequential application was more effective than the simultaneous protocol compared with the 24 h single applications. When the application of antibiotics and phages alone was compared with their combined administration in 48 h. The sequential and simultaneous applications were more effective than single applications in all strains except two. We observed that combination of phage and antibiotics could increase biofilm eradication and provides new insights into the use of bacteriophages and antibiotics in the treatment of biofilm-associated infections caused by antibiotic-resistant bacteria.

Investigation of the probiotic and metabolic potential of Fructobacillus tropaeoli and Apilactobacillus kunkeei from apiaries.

Honeybee products have been among important consumer products throughout history. Microbiota has attracted attention in recent years due to both their probiotic value and industrial potential. Fructophilic lactic acid bacteria (FLAB), whose field of study has been expanding rapidly in the last 20 years, are among the groups that can be isolated from the bee gut. This study aimed to isolate FLAB from the honeybees of two different geographic regions in Turkey and investigate their probiotic, metabolic and anti-quorum sensing (anti-QS) potential. Metabolic properties were investigated based on fructose toleration and acid and diacetyl production while the probiotic properties of the isolates were determined by examining pH, pepsin, pancreatin resistance, antimicrobial susceptibility, and antimicrobial activity. Anti-QS activities were also evaluated with the Chromobacterium violaceum biosensor strain. Two FLAB members were isolated and identified by the 16S rRNA analysis as Fructobacillus tropaeoli and Apilactobacillus kunkeei, which were found to be tolerant to high fructose, low pH, pepsin, pancreatin, and bile salt environments. Both isolates showed anti-QS activity against the C. violaceum biosensor strain and no diacetyl production. The daily supernatants of the isolates inhibited the growth of Enterococcus faecalis ATCC 29212 among the selected pathogens. The isolates were found resistant to kanamycin, streptomycin, erythromycin, and clindamycin. In the evaluation of the probiotic potential of these species, the negative effect of antibiotics and other chemicals to which honeybees are directly or indirectly exposed draws attention within the scope of the "One Health" approach.

Development and In vitro Evaluation of Nifedipine Gel Formulations for Anorectal Applications.

OBJECTIVE: Current study focuses on the formulation and characterization of lipophilic and hydrophilic gel formulations of nifedipine to treat anal fissure via anodermal application. METHODS: Lipophilic gels were prepared with Aerosil grades as gelling agents in bulk oils. Polyethylene glycols, hydroxypropyl methylcellulose, and Carbopol® 974P were used as gelling agents in water and propylene glycol for forming hydrophilic gels. The effect of repeated Freeze-Thaw Cycles (FT-C) on microstructures of the gels was investigated by examining viscosity, rheology and textural properties. Aerosil 200 containing lipophilic gels exhibited thixotropic behavior with plastic flow properties and higher viscosities. RESULT: Accordingly, their compressibility and adhesiveness increased. FT-C caused notable changes in microstructures and textural properties of the lipophilic gels excluding the formulation containing Aerosil 200-in-isopropyl myristate. Among the hydrophilic gels, the viscosity of Carbopol® 974P gels increased depending on the amount of polymer, triethanolamine and water; these gels featured plastic flow without thixotropic behavior. Their compressibility and adhesiveness were higher than other gel formulations with stable post-FT-C characteristics. The higher flux values of nifedipine were observed from water containing Carbopol® 974P gel. CONCLUSION: The results of the stability tests showed that the Carbopol® 974P gel had a longer shelf life than the Aerosil 200-in-isopropyl myristate gel.

Antimicrobial screening of some selected Turkish medicinal plants.

For many years, plants are used for treatment of various diseases. In general, plants have rather more therapeutic benefits and fewer adverse effects compared with the synthetic drugs. The purpose of this study was to determine the in vitro antimicrobial potentials of fifteen plant species from Anatolia region of Turkey against some selected bacteria and a yeast strain. The extracts from belong to nine families were examined against Bacillus subtilis ATCC 6633, Staphylococcus aureus ATCC 43300 (MRSA), Staphylococcus aureus ATCC 25923, Pseudomonas aeruginosa ATCC 27853, Escherichia coli ATCC 25922 and Candida albicans ATCC 10231 using disc diffusion and micro dilution methods. According to the obtained results, all plant extracts showed different ranges of antibacterial activity against S. aureus ATCC 43300 and S. aureus ATCC 25923 strains. Flower and leaves extracts of R. lutea, leaves extract of E. ritro, flower and leaves extracts of H. europaeum, leaves extract of E. macroclada, fruit and leaves extracts of Z. fabago, flower extract of C.crupinastrum, leaves extract of D. tenuifolia showed different ranges of antifungal activity against C. albicans.

Antimicrobial Activities of Extracts and Isolated Coumarins from the Roots of Four Ferulago Species Growing in Turkey.

Ferulago species have been utilized since ancient times as digestive, sedative, aphrodisiac, along with in salads or as a spice due to their special odors. The study reports isolation and characterization of bioactive compounds of Ferulago pachyloba (F. pachyloba), Ferulago trachycarpa (F. trachycarpa), Ferulago bracteata (F. bracteata), and Ferulago blancheana (F. blancheana) via bioassay guided fractionation and isolation process. The structures of compounds were elucidated by detailed spectroscopic analyses. They were also assessed for their activities at 1000-31.25 µg/mL concentrations by microbroth-dilution methods. Antimicrobial activity of aqueous, methanol extracts and dichloromethane, ethyl acetate, n-butanol and aqueous residue fractions of methanol extracts from aerial parts and roots of species along with isolated compounds [osthole, imperatorin, bergapten, prantschimgin, peucedanol-2'-benzoate, grandivitinol, suberosin, xanthotoxin, felamidin, marmesin, umbelliferone, ulopterol and a sterol mixture consisted of stigmasterol, ß-sitosterol] were evaluated. Antimicrobial effect has been seen against Gram-negative, Gram-positive bacteria, and a yeast C. albicans at a concentration between 31.25 and 62.5 µg/mL. Especially, C. albicans (MIC = 31.25 µg/mL) was the most inhibited microorganism. Moreover, growth of P. aeruginosa, B. subtilis, E. coli, and S. aureus were inhibited at 62.5 µg/mL MIC values. Among tested samples prantschimgin and dichloromethane fraction of aerial parts from F. pachyloba showed the best activity against C. albicans (MIC = 31.25 µg/mL). However, among aqueous extracts and residue fractions, only F. blancheana aerial parts, F. trachycarpa aerial parts, and roots and F. bracteata roots showed activity against C. albicans. Among microorganisms E. coli was found to be the least affected.

Quorum sensing signals and related virulence inhibition of Pseudomonas aeruginosa by a potential probiotic strain's organic acid.

Studies conducted in recent years show that pathogen bacteria are not asocial assets and they use the cell to cell communication mechanism called quorum sensing that depends on population density to adapt changing environmental conditions. This mechanism is coordinate gene expression of various bacterial factors like bioluminescence, antibiotic biosynthesis, plasmid conjugation and virulence. Bacteria communicate with each other by producing signal molecules and regulate the production of virulence factors that have importance in the pathogenity formation. Virulence mechanisms of Pseudomonas aeruginosa, which causes various types of infections in humans, are also regulated by quorum sensing. Nowadays, biotechnological researches are focused on the development of homoserine lactone antagonists. The use of these type of molecules are considered to be a new treatment approach for blocking communication between bacteria and reducing virulence, therefore improving infection control. In this study, lactic acid of a potential probiotic Pediococcus acidilactici M7 strain isolated from newborn faeces was used to evaluate the inhibitory effect on quorum sensing signal molecules and some virulence factors of clinical Pseudomonas aeruginosa isolates. Results showed that lactic acid has an inhibitory effect on short-chain HSL production and swarming-swimming-twitching motility, elastase, protease, pyocyanin, and biofilm production of Pseudomonas aeruginosa isolates in certain quantities that are regulated by the quorum sensing system.

A Comparative Study on the in vitro Antioxidant and Antimicrobial Potentials of Three Endemic Ononis L. Species from Turkey.

OBJECTIVES: In this study, the antioxidant capacity, antimicrobial activity and phenolic contents of aerial parts and roots extracts of three endemic Ononis L. (Leguminosae) species (O. sessilifolia Bornm., O. basiadnata Hub. & Mor., O. macrosperma Hub. & Mor.) were investigated for the first time. MATERIALS AND METHODS: The phenolic contents of the extracts [water and ethanol (EtOH)] and fractions [dichloromethane, EtOAc and n-butanol] were determined using Folin-Ciocalteu's phenol reagent. Also, their antioxidant capacities were studied using qualitative DPPH˙ (1,1-diphenyl-2-picrylhdrazyl radical) and TBA assays. The antimicrobial activity of these extracts and fractions compared with standard antibiotics were studied using disc diffusion assays against various Gram-positive and Gram-negative bacteria and fungi. RESULTS: The total phenolic contents of the water extracts were found to range between 14.78-80.33 mg/g, and the EtOH extracts ranged from 67.19-145.33 mg/g. EtOAc fractions of the three species were rich in terms of total phenolic contents when compared with other extracts (242.56-620.89 mg/g). The most significant results in the TBA assays were obtained in EtOH extracts of O. macrosperma (IC50=0.13±0.17 µg/mL), O. sessilifolia (IC50=1.41±0.58 µg/mL) and root (IC50=1.96±0.39 µg/mL). CONCLUSION: EtOAc fractions rich in phenolic content were also found to be the most effective in antioxidant activity assays. Although all water extracts had no antimicrobial activity, EtOH extracts and n-butanol fractions showed generally moderate activity against bacteria. Some EtOAc fractions except for O. sessilifolia showed less activity against Escherichia coli, Staphylococcus aureus, MRSA and Candida albicans.

Antimicrobial Activities of New Indole Derivatives Containing 1,2,4-Triazole, 1,3,4-Thiadiazole and Carbothioamide.

OBJECTIVES: In new antimicrobial drug development studies, indole and its derivatives create an important class of compounds. In addition, azoles and their derivatives were recognized to be associated with a variety of biologic activities such as antibacterial and antifungal. In this study antimicrobial activities of some indole derivatives mainly substituted with 1,2,4-triazole, 1,3,4-thiadiazole and hydrazinecarbothioamide were investigated to evaluate their efficacy. MATERIALS AND METHODS: The efficacy of new compounds was evaluated using 2-fold serial dilutions against Staphylococcus aureus, MRSA, Escherichia coli, Bacillus subtilis, Candida albicans, and Candida krusei. RESULTS: The MIC was determined for test compounds and for the reference standards sultamicillin, ampicillin, fluconazole, and ciprofloxacin. CONCLUSION: The compounds possessed a broad spectrum of activity having MIC values of 3.125-50 µg/mL against the tested microorganisms. This study provides valuable evidence that the indole-triazole derivative compound 3d holds significant promise as a novel antibacterial and antifungal lead compound.

Ofloxacin Loaded Electrospun Fibers for Ocular Drug Delivery: Effect of Formulation Variables on Fiber Morphology and Drug Release.

Ofloxacin (OFL) loaded poly(ε-caprolactone) (PCL) and PCL: poly(butylene succinate) PBS fibers as a drug delivery system in the treatment of ocular infections were prepared by electrospinning. In particular, the effect of some formulation variables including polymer:drug ratio (9:1, 8:2 and 7:3 w/w), solvent systems like dichloromethane (DCM), N,N-dimethylformamide (DMF), N,Ndimethylacetamide (DMAc) and dimethylsulfoxide (DMSO), polymer blends of PCL:PBS at 80:20, 60:40 and 40:60 ratios on fiber morphology, fiber size were investigated. The morphology and diameter of the electrospun fibers were investigated by scanning electron microscopy (SEM) images also the thermal properties were evaluated by differential scanning calorimetry (DSC). The drug release behaviour from fibers and in vitro antibacterial activity were also studied. It was noticed that the average fiber diameter decreased with decreasing polymer amount in initial composition meanwhile the release of drug increased with increasing amount of drug in formulations. Solvent system of DCM:DMF at 80:20 ratio improved fiber morphology and resulted in a reduction in fiber diameter. It was found that smooth surface, flexible fibers with uniform morphology were obtained with 80:20 ratio of PCL:PBS compositions. All fibers showed a burst release of OFL. The initial amount of the released OFL was found to vary as a function of PCL:OFL ratio and polymer composition in the fiber. The microbiological activity of optimized formulation was evaluated using P. aeruginosa, S. epidermidis, S. Aureus and E. coli strains and the results of this study clearly demonstrated that freely released OFL from fibers inhibited the growth of the tested bacteria. The process of electrospinning had no adverse effect on the activity of incorporated drug in fibers.

Novel inhibitors of the methicillin-resistant Staphylococcus aureus (MRSA)-pyruvate kinase.

Novel bisindolyl-cycloalkane indoles resulted from the reaction of aliphatic dialdehydes and indole. As bisindolyl-natural alkaloid compounds have recently been reported as inhibitors of the methicillin-resistant Staphylococcus aureus (MRSA)-pyruvate kinase (PK), we tested our novel compounds as MRSA PK inhibitors and now report first inhibiting activities. We discuss structure-activity relationships of structurally varied compounds. Activity influencing substituents have been characterized and relations to antibacterial activities of the most active compounds have been proved.

Discovery of bisindolyl-substituted cycloalkane-anellated indoles as novel class of antibacterial agents against S. aureus and MRSA.

Antibiotic resistance is an ongoing problem in the treatment of bacterial diseases. Among the various antibacterial infections Staphylococcus aureus infections remain critical due to the increasing resistances, especially against the methicillin-resistant S. aureus (MRSA). We discovered novel antibacterial compounds with activities against both S. aureus and MRSA types. Structure-activity relationships (SAR) are discussed and show that the activity depends on the ring size of the anellated cycloalkane. Moreover, first substituent effects have been investigated for both the cycloalkane and the indole residues.

[Detection of plasmid-mediated AmpC beta-lactamase in clinical isolates of cefoxitin-resistant Escherichia coli and Klebsiella pneumoniae]. / Sefoksitine Dirençli Escherichia coli ve Klebsiella pneumoniae Klinik Izolatlarinda Plazmid Aracili AmpC Beta-Laktamaz Tespiti.

Extended spectrum beta-lactamases (ESBL) or AmpC beta-lactamases may be associated with false cephalosporin susceptibility results. Although there are well-established methods for screening and confirmation of class A (ESBL) and class B metallobeta-lactamases (MBL), there is no current guideline for the detection of AmpC beta-lactamases. The aim of this study was to evaluate the performances of three different phenotypic tests [boronic acid (BA) - klavulanic acid (CA) inhibition test, AmpC disk test (TRISEDTA impregnanted), modified 3-dimensional test (M3DT)] for the detection of AmpC beta-lactamases. A total of 50 (42 were Escherichia coli and eight were Klebsiella pneumoniae) cefoxitin-insusceptible strains were collected during June-September 2009. Multiplex PCR was used as the genotypic confirmation test by using DHA, CIT, MOX, FOX and EBC primers. Twenty-five (50%) of 50 cefoxitin-insusceptible strains yielded positive result by BA-CA test. Twenty two (88%) of 25 BA-CA positive strains yielded positive result by multiplex PCR and all of them belonged to CIT family (CMY-2 to CMY-7, LAT-1 to LAT-4 and BIL-1 type) of AmpC beta-lactamases. One strain harboured both CIT and EBC family of AmpC beta- lactamases, one strain harboured CIT + MOX + ESBL. DHA and FOX family of AmpC beta-lactamases were not detected in this study. Both AmpC disk test and M3DT yielded positive test with 11 (52.3%) of 21 AmpC enzyme producing strains (except for one of the PCR positive strain which couldn't be screened by M3DT and AmpC disk test). When BA was added to CA inhibition test, the number of positive isolates of ESBL increased from 13 to 14 (63.6%) due to inhibition of AmpC with BA. Hovewer, the strains which yielded negative results by 3-aminophenylboronic acid (3-APB) were tested again by benzeneboronic acid. Three strains were also found to be positive with benzeneboronic acid. The results of this study indicated that BA test with benzene boronic acid or 3-APB warranted further study. In conclusion, for the phenotypic detection of AmpC beta-lactamases, BA-CA test is simple to perform and easy to interpret. Briefly, in order to prevent the masking effect of ESBL, CA must be added to the BA inhibition test. Also in order to prevent the masking effect of AmpC beta-lactamases on ESBL detection, BA must be added to the CA inhibition test.

Antimicrobial evaluation of indole-containing hydrazone derivatives.

There has been an increasing importance of drug-resistant pathogens in clinical microbiological and antibacterial research. Indoles and hydrazone-type compounds constitute important classes of compounds in the search for effective agents against multidrug-resistant microbial infections. In this study a series of 1-methylindole-3-carboxaldehyde hydrazone derivatives were evaluated for their in vitro antimicrobial activities using the two-fold serial dilution technique against Staphylococcus aureus, methicillin-resistant S. aureus, methicillin-resistant S. aureus isolate, Escherichia coli, Bacillus subtilis, and Candida albicans. The minimum inhibitory concentration (MIC) of the test compounds and the reference standards sultamicillin, ampicillin, fluconazole, and ciprofloxacin was determined. All compounds possessed a broad spectrum of activity having MIC values of 6.25-100 microg/ml against the tested microorganisms. Aromaticity and disubstitution of the phenyl ring with especially fluorine and chlorine atoms were found to be significant for the antimicrobial activity

Synthesis and antimicrobial evaluation of some new substituted purine derivatives.

A series of 8,9-disubstituted adenines (4, 5, 8), 6-substituted aminopurines (10-13) and 9-(p-fluorobenzyl/cyclopentyl)-6-substituted aminopurines (16, 17, 19-30) have been prepared and the antimicrobial activities of these compounds against Staphylococcus aureus, methicillin-resistant S. aureus (MRSA, standard and clinical isolate), Bacillus subtilis, Escherichia coli and Candida albicans were evaluated. 6-[(N-phenylaminoethyl)amino]-9H-purine (12) which has no substitution at N-9 position and 9-cyclopentyl-6-[(4-fluorobenzyl)amino]-9H-purine (24) exhibited excellent activity against C. albicans with MIC 3.12 microg/mL. These compounds displayed better antifungal activity than that of standard oxiconazole. Furthermore, compound 22 carrying 4-chlorobenzylamino group at the 6-position of the purine moiety exhibited comparable antibacterial activity with that of the standard ciprofloxacin against both of the drug-resistant bacteria (MRSA, standard and clinical isolate).

Synthesis and in vitro antimicrobial activity of some novel substituted benzimidazole derivatives having potent activity against MRSA.

The novel benzimidazole derivatives (3, 5, 8, 9, 12-14, 18-41) were prepared in this paper and the antimicrobial activities of these compounds against Staphylococcus aureus, methicillin-resistant S. aureus (MRSA, standard and clinical isolates), Bacillus subtilis, Escherichia coli and Candida albicans were evaluated. Compounds 24-26 which have no substitution of N-1 position displayed better antibacterial activities than those of standards (ciprofloxacin, ampicillin and sultamicillin) against both the drug-resistant bacteria (MRSA, standard and clinical isolates). These derivatives (24-26), 2,5,6-trihalogenobenzimidazole analogues (8, 12), 5,6-dichloro-2-amino derivative (13), and 5-chloro-2-(4-benzyloxyphenyl)benzimidazole (35) exhibited the most potent antibacterial activity with MIC 3.12 microg/ml against S. aureus.

Synthesis and antimicrobial activity of some novel thiazolidine-2,4-dione derivatives.

In this study, a series of phenylethylsulfanyl-1,3-thiazolo-thiazolidine-2,4-dione derivatives (VII a-f, VIII a-f) and 5-methyl-[1,2,4]triazolyl-sulfanyl-1,3-thiazolo-thiazolidine-2,4-dione derivatives (IX a-f, X a-f) were synthesized and evaluated for their antibacterial and antifungal activities against S. aureus (ATCC 25923), methicillin resistant S. aureus (MRSA ATCC 43300), B. subtilis (ATCC 6633), E. coli (ATCC 23556) and C. albicans (ATCC10145). All the compounds were found active against used bacteria.

Investigation of antimicrobial activities of indole-3-aldehyde hydrazide/hydrazone derivatives.

BACKGROUND: Indoles and hydrazone-type compounds constitute an important class of compounds for new drug development in order to discover an effective compound against multi-drug-resistant microbial infections. METHODS: A series of indole-3-aldehyde and 5-bromoindole-3-aldehyde hydrazide and hydrazones was evaluated for their in vitro antimicrobial activities using the 2-fold serial dilution technique against Staphylococcus aureus, methicillin-resistant S. aureus (MRSA), Escherichia coli, Bacillus subtilis and Candida albicans. The minimum inhibitory concentration (MIC) was determined for test compounds and for the reference standards sultamicillin, ampicillin, fluconazole and ciprofloxacin. RESULTS: Compounds possessed a broad spectrum of activity having MIC values of 6.25-100 mg/ml against the tested microorganisms. Compounds 1a-1j, in particular, displayed better activity against MSRA and significant activity against S. aureus relative to ampicillin. Unexpectedly, indole nicotinic acid hydrazides showed no significant activity while indole anisic acid hydrazides displayed better activity. CONCLUSION: The results may be instructive to researchers attempting to gain more understanding of the antimicrobial activity of indole hydrazide/hydrazone-type compounds.

Synthesis and antimicrobial activity of some novel 2-[4-(substituted piperazin-/piperidin-1-ylcarbonyl)phenyl]-1H-benzimidazole derivatives.

In this study, we report the synthesis and antimicrobial evaluation of several new 4-(1H-benzimidazol-2-yl)benzamides (11-30) and 5-chloro-1-(p-fluorobenzyl)-2-{4-[(4-methylpiperazin-1-yl)carbonyl]phenyl}-1H-benzimidazole (33). Compound 20 exhibited the best antibacterial activity with MIC value of 6.25 microg/mL against Staphylococcus aureus and methicillin-resistant Staphylococcus aureus (MRSA). Significant antifungal activities were obtained with the compounds 13, 14, 18, 19, and 33 with MIC values of 3.12 microg/mL which are close to fluconazole.

Antimicrobial and antiviral screening of novel indole carboxamide and propanamide derivatives.

A few series of indole derivatives were screened for antimicrobial, antifungal and anti-HBV activities. The compounds were tested for their in vitro antibacterial activity against Staphylococcus aureus, Bacillus subtilis, Escherichia coli and for their antifungal activity against Candida albicans using a disc diffusion method, which measures the diameter of the inhibition zone around a paper disc soaked in a solution of the test compounds. The antimicrobial activity results showed that all compounds are as a active as the standard compound ampicillin against Staphylococcus aureus. It was also found that indole carboxamide derivatives, substituted at 3-position with several benzyl groups, showed better inhibition of Bacillus subtilis than their congeners substituted at 2-position. Activity patterns of the compounds against Escherichia coli and Staphylococcus aureus were found slightly different by the same method. In this case, there was no correlation between structure and activity of the compounds. The antifungal activity of carboxamide derivatives was found higher compared to that of the propanamide derivatives. The minimum inhibitory concentration (MIC) values of some indole derivatives were also determined by the tube dilution technique. The MIC values of the compounds were found nearly 20- to 100-fold smaller compared to the standard compounds ciprofloxacin and ampicillin (1.56-3.13 microg/ml and 1.56-12.5 microg/ml, respectively) against Staphylococcus aureus, Bacillus subtilis and Escherichia coli. The MIC values of the tested compounds showed that these are better inhibitors for Candida albicans. Indole derivatives were screened by the anti-HBV susceptibility test. No compound showed good inhibition against the HBV virus.