Probiotic Lactobacilli Interfere with <Emphasis Type="Italic">Streptococcus mutans</Emphasis> Biofilm Formation In Vitro

In clinical studies, probiotic bacteria have decreased the counts of salivary mutans streptococci (MS). We compared the effects of probiotic Lactobacillus strains on the biofilm formation of Streptococcus mutans. The bacterial strains used included four S. mutans strains (reference strains NCTC 10449 and Ingbritt and clinical isolates 2366 and 195) and probiotic strains Lactobacillus rhamnosus GG, L. plantarum 299v, and L. reuteri strains PTA 5289 and SD2112. The ability of MS to adhere and grow on a glass surface, reflecting biofilm formation, was studied in the presence of the lactobacilli (LB). The effect of LB culture supernatants on the viability of the MS was studied as well. All of the LB inhibited the biofilm formation of the clinical isolates of MS (P < 0.001). The biofilm formation of the reference strains of MS was also inhibited by the LB, but L. plantarum and L. reuteri PTA 5289 showed a weaker inhibition when compared to L. reuteri SD2112 and L. rhamnosus GG. Viable S. mutans cells could be detected in the biofilms and culture media only when the experiments were performed with the L. reuteri strains. The L. reuteri strains were less efficient in killing the MS also in the tests performed with the culture supernatants. The pHs of the supernatants of L. reuteri were higher compared to those of L. rhamnosus GG and L. plantarum; P < 0.001. In conclusion, our results demonstrated that four commonly used probiotics interfered with S. mutans biofilm formation in vitro, and that the antimicrobial activity against S. mutans was pH-dependent.     

Characterization of the <Emphasis Type="Italic">codY</Emphasis> gene and its influence on biofilm formation in <Emphasis Type="Italic">Bacillus </Emphasis><Emphasis Type="Italic">cereus</Emphasis>

The foodborne pathogen Bacillus cereus can form biofilms on various food contact surfaces, leading to contamination of food products. To study the mechanisms of biofilm formation by B. cereus, a Tn5401 library was generated from strain UW101C. Eight thousand mutants were screened in EPS, a low nutrient medium. One mutant (M124), with a disruption in codY, developed fourfold less biofilm than the wild-type, and its defective biofilm phenotype was rescued by complementation. Addition of 0.1% casamino acids to EPS prolonged the duration of biofilms in the wild-type but not codY mutant. When decoyinine, a GTP synthesis inhibitor, was added to EPS, biofilm formation was decreased in the wild-type but not the mutant. The codY mutant produced three times higher protease activity than the wild-type. Zymogram and SDS-PAGE data showed that production of the protease (∼130 kDa) was repressed by CodY. Addition of proteinase K to EPS decreased biofilm formation by the wild-type. Using a dpp-lacZ fusion reporter system, it was shown that that the B. cereus CodY can sense amino acids and GTP levels. These data suggest that by responding to amino acids and intracellular GTP levels CodY represses production of an unknown protease and is involved in biofilm formation.     

Arctic Actinomycetes as Potential Inhibitors of <Emphasis Type="Italic">Vibrio cholerae</Emphasis> Biofilm

The aim of this study was to identify novel biofilm inhibitors from actinomycetes isolated from the Arctic against Vibrio cholerae, the causative agent of cholera. The biofilm inhibitory activity of actinomycetes was assessed using biofilm assay and was confirmed using air–liquid interphase coverslip assay. The potential isolates were identified using 16S rRNA gene sequencing. Of all, three isolates showed significant biofilm inhibition against V. cholerae. The results showed that 20% of the actinomycetes culture supernatant could inhibit up to 80% of the biofilm formation. When different extracted fractions were assessed, significant biofilm inhibition activity was only seen in the diethyl ether fraction of A745. At 200 μg ml⁻¹ of diethyl ether fraction, 60% inhibition of V. cholerae biofilm was observed. The two potential isolates were found to be Streptomyces sp. and one isolate belonged to Nocardiopsis sp. This is the first report showing a Streptomyces sp. and Nocardiopsis sp. isolated from the Arctic having a biofilm inhibitory activity against V. cholerae. The spread of drug resistant V. cholerae strains is a major clinical problem and the ineffectiveness in antibiotic treatment necessitates finding new modes of prevention and containment of the disease, cholera. The formation of biofilms during the proliferation of V. cholerae is linked to its pathogenesis. Hence, the bioactive compound from the culture supernatant of the isolates identified in this study may be a promising source for the development of a potential quorum sensing inhibitors against V. cholerae.     

Anticandidal Efficacy of Cinnamon Oil Against Planktonic and Biofilm Cultures of <Emphasis Type="Italic">Candida parapsilosis</Emphasis> and <Emphasis Type="Italic">Candida orthopsilosis</Emphasis>

Candida parapsilosis is yeast capable of forming biofilms on medical devices. Novel approaches for the prevention and eradication of the biofilms are desired. This study investigated the anticandidal activity of sixteen essential oils on planktonic and biofilm cultures of C. parapsilosis complex. We used molecular tools, enumeration of colony-forming units, the colourimetric MTT assay, scanning electron microscopy (SEM) and a chequerboard assay coupled with software analyses to evaluate the growth kinetics, architecture, inhibition and reduction in biofilms formed from environmental isolates of the Candida parapsilosis complex; further, we also evaluated whether essential oils would interact synergistically with amphotericin B to increase their anticandidal activities. Of the environmental C. parapsilosis isolates examined, C. parapsilosis and C. orthopsilosis were identified. Biofilm growth on polystyrene substrates peaked within 48 h, after which growth remained relatively stable up to 72 h, when it began to decline. Details of the architectural analysis assessed by SEM showed that C. parapsilosis complex formed less complex biofilms compared with C. albicans biofilms. The most active essential oil was cinnamon oil (CO), which showed anticandidal activity against C. orthopsilosis and C. parapsilosis in both suspension (minimum inhibitory concentration—MIC—250 and 500 μg/ml) and biofilm (minimum biofilm reduction concentration—MBRC—1,000 and 2,000 μg/ml) cultures. CO also inhibited biofilm formation (MBIC) at concentrations above 250 μg/ml for both species tested. However, synergism with amphotericin B was not observed. Thus, CO is a natural anticandidal agent that can be effectively utilised for the control of the yeasts tested.     

Interaction of sortase A and lipase 2 in the inhibition of <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> biofilm formation

Recombinant sortase A (SrtA) was used to immune rabbit, and the inhibitory activity of anti-SrtA serum on Staphylococcus aureus biofilm formation was tested. Biofilm formation was inhibited by anti-SrtA rabbit serum in S. aureus ATCC25923 and two clinical isolated strains. The antiserum was separated into two fractions, and the main component with the inhibitory activity was demonstrated to be the IgG fraction. Two proteins interact with the IgG fraction were identified by using an in vitro pull-down assay and were confirmed to be lipase 2 and γ-hemolysin by mass spectrometry. Cross-interaction between SrtA and lipase 2 was further confirmed by Western blotting. Addition of anti-lipase 2 serum in the culture medium also showed inhibitory effect against biofilm formation. Together, our study suggests anti-SrtA serum inhibits S. aureus biofilm formation and lipase 2 is one of the targets of anti-SrtA serum in this inhibition process. This is the first study to demonstrate the roles of antisera against SrtA and lipase 2 in the inhibition of biofilm formation in S. aureus.     

Inhibition of <Emphasis Type="Italic">Vibrio</Emphasis> biofilm formation by a marine actinomycete strain A66

China remains by far the largest aquaculture producer in the world. However, biofilms formed by pathogenic Vibrio strains pose serious problems to marine aquaculture. To provide a strategy for biofilm prevention, control, and eradication, extracts from 88 marine actinomycetes were screened. Thirty-five inhibited the biofilm formation of Vibrio harveyi, Vibrio vulnificus, and Vibrio anguillarum at a concentration of 2.5% (v/v). Thirty-three of the actinomycete extracts dispersed the mature biofilm. Six extracts inhibited the quorum-sensing system of V. harveyi by attenuating the signal molecules N-acylated homoserine lactones’ activity. Strain A66, which was identified as Steptomyces albus, both attenuated the biofilms and inhibited their quorum-sensing system. It is suggested that strain A66 is a promising candidate to be used in future marine aquaculture.     

Antipathogenic potential of marine <Emphasis Type="Italic">Bacillus</Emphasis> sp. SS4 on <Emphasis Type="Italic">N</Emphasis>-acyl-homoserine-lactone-mediated virulence factors production in <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> (PAO1)

Antipathogenic therapy is an outcome of the quorum-sensing inhibition (QSI) mechanism, which targets autoinducer-dependent virulent gene expression in bacterial pathogens. N-acyl homoserine lactone (AHL) acts as a key regulator in the production of virulence factors and biofilm formation in Pseudomonas aeruginosa PAO1 and violacein pigment production in Chromobacterium violaceum. In the present study, the marine bacterial strain SS4 showed potential QSI activity in a concentration-dependent manner (0.5–2 mg/ml) against the AHL-mediated violacein production in C. violaceum (33–86%) and biofilm formation (33–88%), total protease (20–65%), LasA protease (59–68%), LasB elastase (36–68%), pyocyanin (17–86%) and pyoverdin productions in PAO1. The light and confocal laser scanning microscopic analyses confirmed the reduction of the biofilm-forming ability of PAO1 when treated with SS4 extract. Furthermore, the antibiofilm potential was confirmed through static biofilm ring assay, in which ethyl acetate extract of SS4 showed concentration-dependent reduction in the biofilm-forming ability of PAO1. Thus, the result of this study clearly reveals the antipathogenic and antibiofilm properties of the bacterial isolate SS4. Through 16S rDNA analysis, the strain SS4 was identified as Bacillus sp. (GenBank Accession Number: GU471751).     

<Emphasis Type="Italic">Agrobacterium</Emphasis><Emphasis Type="Italic">tumefaciens</Emphasis>-mediated transformation of callus cells of <Emphasis Type="Italic">Crataegus</Emphasis><Emphasis Type="Italic">aronia</Emphasis>

A genetic transformation system has been developed for callus cells of Crataegus aronia using Agrobacterium tumefaciens. Callus culture was established from internodal stem segments incubated on Murashige and Skoog (MS) medium supplemented with 5 mg l⁻¹ Indole-3-butyric acid (IBA) and 0.5 mg l⁻¹ 6-benzyladenine (BA). In order to optimize the callus culture system with respect to callus growth and coloration, different types and concentrations of plant growth regulators were tested. Results indicated that the best average fresh weight of red colored callus was obtained on MS medium supplemented with 2 mg l⁻¹ 2,4-dichlorophenoxyacetic acid (2,4-D) and 1.5 mg l⁻¹ kinetin (Kin) (callus maintenance medium). Callus cells were co-cultivated with Agrobacterium harboring the binary plasmid pCAMBIA1302 carrying the mgfp5 and hygromycin phosphotransferase (hptII) genes conferring green fluorescent protein (GFP) activity and hygromycin resistance, respectively. Putative transgenic calli were obtained 4 weeks after incubation of the co-cultivated explants onto maintenance medium supplemented with 50 mg l⁻¹ hygromycin. Molecular analysis confirmed the integration of the transgenes in transformed callus. To our knowledge, this is the first time to report an Agrobacterium-mediated transformation system in Crataegus aronia.     

<Emphasis Type="Italic">Salinarchaeum laminariae</Emphasis> gen. nov., sp. nov.: a new member of the family <Emphasis Type="Italic">Halobacteriaceae</Emphasis> isolated from salted brown alga <Emphasis Type="Italic">Laminaria</Emphasis>

Halophilic archaeal strains R26^T and R22 were isolated from the brown alga Laminaria produced at Dalian, Liaoning Province, China. Cells from the two strains were pleomorphic rods and Gram negative, and colonies were red pigmented. Strains R26^T and R22 were able to grow at 20–50°C (optimum 37°C) in 1.4–5.1 M NaCl (optimum 3.1–4.3 M) at pH 5.5–9.5 (optimum pH 8.0–8.5) and neither strain required Mg²⁺ for growth. Cells lyse in distilled water and the minimum NaCl concentration required to prevent cell lysis was 8% (w/v) for strain R26^T and 12% (w/v) for strain R22. The major polar lipids of the two strains were phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester and minor phosphatidylglycerol sulfate; glycolipids were not detected. Phylogenetic analyses based on 16S rRNA genes and rpoB′ genes revealed that strains R26^T and R22 formed a distinct clade with the closest relative, Natronoarchaeum mannanilyticum. The DNA G+C content of strains R26^T and R22 was 65.8 and 66.4 mol%, respectively. The DNA–DNA hybridization value between strains R26^T and R22 was 89%. The phenotypic, chemotaxonomic and phylogenetic properties suggest that the strains R26^T and R22 represent a novel species in a new genus within the family Halobacteriaceae, for which the name Salinarchaeum laminariae gen. nov., sp. nov. is proposed. The type strain is R26^T (type strain R26^T = CGMCC 1.10590^T = JCM 17267^T, reference strain R22 = CGMCC 1.10589).     

<Emphasis Type="SmallCaps">l</Emphasis>-Proline nutrition and catabolism in <Emphasis Type="Italic">Staphylococcus saprophyticus</Emphasis>

Staphylococcus saprophyticus strains ATCC 15305, ATCC 35552, and ATCC 49907 were found to require l-proline but not l-arginine for growth in a defined culture medium. All three strains could utilize l-ornithine as a proline source and contained l-ornithine aminotransferase and Δ¹-pyrroline-5-carboxylate reductase activities; strains ATCC 35552 and ATCC 49907 could use l-arginine as a proline source and had l-arginase activity. The proline requirement also could be met by l-prolinamide, l-proline methyl ester, and the dipeptides l-alanyl-l-proline and l-leucyl-l-proline. The bacteria exhibited l-proline degradative activity as measured by the formation of Δ¹-pyrroline-5-carboxylate. The specific activity of proline degradation was not affected by addition of l-proline or NaCl but was highest in strain ATCC 49907 after growth in Mueller–Hinton broth. A membrane fraction from this strain had l-proline dehydrogenase activity as detected both by reaction of Δ¹-pyrroline-5-carboxylate with 2-aminobenzaldehyde (0.79 nmol min⁻¹ mg⁻¹) and by the proline-dependent reduction of p-iodonitrotetrazolium (20.1 nmol min⁻¹ mg⁻¹). A soluble fraction from this strain had Δ¹-pyrroline-5-carboxylate dehydrogenase activity (88.8 nmol min⁻¹ mg⁻¹) as determined by the NAD⁺-dependent oxidation of dl-Δ¹-pyrroline-5-carboxylate. Addition of l-proline to several culture media did not increase the growth rate or final yield of bacteria but did stimulate growth during osmotic stress. When grown with l-ornithine as the proline source, S. saprophyticus was most susceptible to the proline analogues L-azetidine-2-carboylate, 3,4-dehydro-dl-proline, dl-thiazolidine-2-carboxylate, and l-thiazolidine-4-carboxylate. These results indicate that proline uptake and metabolism may be a potential target of antimicrobial therapy for this organism.     

Synergistic effect of green tea extract and probiotics on the pathogenic bacteria, <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> and <Emphasis Type="Italic">Streptococcus pyogenes</Emphasis>

The aim of this study was to assess the effect of a commercial green tea extract (TEAVIGO™) on the microbial growth of three probiotic strains (Lactobacillus and Bifidobacterium), as well as three pathogenic bacteria. MIC and co-culture studies were performed. The MICs of the green tea extract against Staphylococcus aureus and Streptococcus pyogenes (100 μg ml⁻¹) were considerably lower than those against the probiotic strains tested (>800 μg ml⁻¹) and Escherichia coli (800 μg ml⁻¹). In co-culture studies, a synergistic effect of the probiotic strains and the green tea extract was observed against both Staph. aureus and Strep. pyogenes. Green tea extract in combination with probiotics significantly reduced the viable count of both pathogens at 4 h and by 24 h had completely abolished the recovery of viable Staph. aureus and Strep. pyogenes. These reductions were more significant than the reductions induced by probiotics or green tea extracts used separately. These results demonstrate the potential for combined therapy using the green tea extract plus probiotics on microbial infections caused by Staph. aureus and Strep. pyogenes. As probiotics and the green tea extract are derived from natural products, treatment with these agents may represent important adjuncts to, or alternatives to, conventional antibiotic therapy.     

Activity of novel inhibitors of <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> biofilms

Staphylococcus aureus is one of the most important pathogens causing chronic biofilm infections. These are becoming more difficult to treat owing to drug resistance, particularly because S. aureus biofilms limit the efficacy of antimicrobial agents, leading to high morbidity and mortality. In the present study, we screened for inhibitors of S. aureus biofilm formation using a natural product library from the Korea Chemical Bank (KCB). Screening by crystal violet-based biomass staining assay identified hit compounds. Further examination of antibiofilm properties of these compounds was conducted and led to the identification of celastrol and telithromycin. In vitro, both celastrol and telithromycin were toxic to planktonic S. aureus and also active against a clinical methicillin-resistant S. aureus (MRSA) isolate. The effect of the compounds on preformed biofilms of clinical MRSA isolates was evaluated by confocal laser scanning microscopy (CLSM), which revealed the absence of typical biofilm architecture. In addition, celastrol and telithromycin inhibited the production of extracellular protein at selected sub-MIC concentrations, which revealed the reduced extracellular polymeric substance (EPS) secretion. Celastrol exhibited greater cytotoxicity than telithromycin. These data suggest that the hit compounds, especially telithromycin, could be considered novel inhibitors of S. aureus biofilm. Although the mechanisms of the effects on S. aureus biofilms are not fully understood, our data suggest that telithromycin could be a useful adjuvant therapeutic agent for S. aureus biofilm-related infections.     

Influence of the culture medium composition on the excreted/secreted proteases from <Emphasis Type="Italic">Streptomyces violaceoruber</Emphasis>

Streptomyces violaceoruber produces two different classes of mycelium, the substrate and the aerial mycelium. Since proteases have been associated with morphological turnover processes in other Streptomyces species, the presence of excretory/secretory proteolytic activities was investigated here in S. violaceoruber culture supernatants. Various polypeptide bands, with apparent molecular masses ranging from 40 to 180 kDa, were detected in soy trypticase broth (STB) culture media supernatants following 72 h of growth, using Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Zymograms showed the presence of five proteolytic enzymes (Spvio1–5), which migrated as bands of 167.7, 130.7, 110.7, 48.3 and 40.9 kDa, respectively. The characterization of these proteases by specific inhibitors showed that Spvio1–4 belong to the serine protease group and Spvio5 corresponds to a cysteine protease. Additionally, Spvio2 and 5 were inhibited by a mixture of EDTA and EGTA, indicating that both require divalent cations. The protease pattern obtained in STB enriched with glucose was identical to that obtained in STB. However, Spvio3 and 4 were absent when nitrogen was added to the culture medium. Cell death was fluorescently detected following 72 h of S. violaceoruber growth in STB and in STB that was enriched with glucose. On the contrary, no cell death was detected in nitrogen-enriched STB media. Additionally, the formation of the aerial mycelium was impaired in solid cultures of STB media enriched with nitrogen. These results demonstrate that the composition of the media influences the morphological turnover of the colony and the pattern of excreted/secreted proteases from S. violaceoruber, and suggest that Spvio3 and 4 are involved in the aerial mycelium formation.     

Biofilm growth of individual and dual strains of <Emphasis Type="Italic">Klebsiella oxytoca</Emphasis> from the dairy industry on ultrafiltration membranes

Formation of biofilms in dairy membrane plants causes membrane pore blocking, product contamination and subsequent economic loss. To investigate the biofilm growth, two Klebsiella oxytoca strains, K. B006 and TR002, previously isolated from New Zealand dairy membrane plants, were grown both individually and combined on three types of ultrafiltration (UF) membranes in different concentrations of whey medium in biofilm reactors (CBR 90, BioSurface Technologies, Bozeman, USA). Biofilms of both the individual and combined strains grew on the membrane surfaces to levels of 4.9–7.99 log colony-forming units (CFU) cm⁻² measured by standard plate counting after removing the cells by sonication. More biofilm grew on used polyethersulfone (PES) membranes than on new PES and polyvinylidene fluoride (PVDF) membranes. Both strains formed good biofilms, although K. B006 formed a denser biofilm than TR002. This corresponded to our previous study on the attachment of these organisms, where K. B006 attached in greater numbers than K. TR002. The dual strains produced a higher biofilm density than single strains on the new membranes. Biofilm density tended to increase with increased whey concentration. The saturated biofilm was approximately 10⁸ CFU cm⁻². PES membranes appeared to support biofilm growth less readily than did PVDF membranes and therefore may be the preferred material for UF membranes to reduce problems with microbial colonisation. Used membranes were more readily colonised with biofilm than were new membranes. Therefore, selecting a membrane type and monitoring membrane age will help manage biofilm development during UF.     

<Emphasis Type="Italic">Staphylococcus aureus</Emphasis> sigma B-dependent emergence of small-colony variants and biofilm production following exposure to <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> 4-hydroxy-2-heptylquinoline-<Emphasis Type="Italic">N-</Emphasis> oxide

Background  

Staphylococcus aureus and Pseudomonas aeruginosa are often found together in the airways of cystic fibrosis (CF) patients. It was previously shown that the P. aeruginosa exoproduct 4-hydroxy-2-heptylquinoline-N-oxide (HQNO) suppresses the growth of S. aureus and provokes the emergence of small-colony variants (SCVs). The presence of S. aureus SCVs as well as biofilms have both been associated with chronic infections in CF.     

Purification and some properties of an extracellular acid protease from <Emphasis Type="Italic">Aspergillus</Emphasis><Emphasis Type="Italic">clavatus</Emphasis>

Acid proteases represent an important group of enzymes, widely used in food, beverage and pharmaceutical industries. For most of these applications the enzymatic preparation must be at least partially purified and free of substances that could change the characteristics of the product or the process. Fungal proteases have replaced other sources because they are easily obtained mainly from Mucor, Rhizopus, Penicillium and Aspergillus species. A strain of Aspergillus clavatus was selected by producing high level of acid protease activity. An extracellular aspartatic protease from this strain was purified 37.2 times with 37% recovery using (NH₄)₂SO₄ fractionation and ion-exchange chromatography. The enzyme was found to be monomeric having a molecular mass of 30.4 kDa. The purified enzyme is an acid protease with optimum pH of 5.5 and temperature for optimum activity of 50 °C. Its high pH stability was verified in the range of 3.5–6.5. The acid protease was strongly inhibited by Hg⁺² and partially inhibited by Cu⁺², Zn⁺² and Mn⁺². The enzyme was sensitive to denaturing agent SDS and activated by thiol-containing reducing agent dithiotreitol (DTT). The protease activity was not influenced by iodoacetic acid, E-64 and PMSF, while it was lightly actived by EDTA and totally inhibited by pepstatin, with a K_i of 7.8 μM, indicating that is an aspartic protease. A. clavatus acid protease presents interesting characteristics for biotechnological process, such as cheese and flavor manufacture and dietary supplements, in which activity and stability in acid pH are required.     

In Vitro Management of Hospital <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> Biofilm Using Indigenous T7-Like Lytic Phage

Pseudomonas aeruginosa, a human pathogen capable of forming biofilm and contaminating medical settings, is responsible for 65% mortality in the hospitals all over the world. This study was undertaken to isolate lytic phages against biofilm forming Ps. aeruginosa hospital isolates and to use them for in vitro management of biofilms in the microtiter plate. Multidrug resistant strains of Ps. aeruginosa were isolated from the hospital environment in and around Pimpri-Chinchwad, Maharashtra by standard microbiological methods. Lytic phages against these strains were isolated from the Pavana river water by double agar layer plaque assay method. A wide host range phage bacterial virus Ps. aeruginosa phage (BVPaP-3) was selected. Electron microscopy revealed that BVPaP-3 phage is a T7-like phage and is a relative of phage species gh-1. A phage at MOI-0.001 could prevent biofilm formation by Ps. aeruginosa hospital strain-6(HS6) on the pegs within 24 h. It could also disperse pre-formed biofilms of all hospital isolates (HS1–HS6) on the pegs within 24 h. Dispersion of biofilm was studied by monitoring log percent reduction in cfu and log percent increase in pfu of respective bacterium and phage on the peg as well as in the well. Scanning electron microscopy confirmed that phage BVPaP-3 indeed causes biofilm reduction and bacterial cell killing. Laboratory studies prove that BVPaP-3 is a highly efficient phage in preventing and dispersing biofilms of Ps. aeruginosa. Phage BVPaP-3 can be used as biological disinfectant to control biofilm problem in medical devices.     

Antimicrobial resistance and presence of <Emphasis Type="Italic">ileS-2</Emphasis> gene encoding mupirocin resistance in clinical isolates of methicillin-resistant <Emphasis Type="Italic">Staphylococcus</Emphasis> sp.

Seventy-eight staphylococcal strains were isolated from surgical-site, blood-stream and other hospital-acquired infections. Eighteen isolates were determined as methicillin (MET)-resistant S. aureus (MRSA), while the remaining were MET-resistant coagulase-negative staphylococci (CoNS). Fifty percent of CoNS strains were multiresistant, while 10 % of isolates were resistant only to β-lactams. Clinical isolates of CoNS were generally more resistant to antimicrobial agents than S. aureus strains. Thirty-nine % of S. aureus strains were resistant only to β-lactams. None of the MRSA strains carried ileS-2 gene; this gene was found in two strains of S. epidermidis.     

<Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> inhibits <Emphasis Type="Italic">in-vitro Candida</Emphasis> biofilm development

Background  

Elucidation of the communal behavior of microbes in mixed species biofilms may have a major impact on understanding infectious diseases and for the therapeutics. Although, the structure and the properties of monospecies biofilms and their role in disease have been extensively studied during the last decade, the interactions within mixed biofilms consisting of bacteria and fungi such as Candida spp. have not been illustrated in depth. Hence, the aim of this study was to evaluate the interspecies interactions of Pseudomonas aeruginosa and six different species of Candida comprising C. albicans, C. glabrata, C. krusei, C. tropicalis, C. parapsilosis, and C. dubliniensis in dual species biofilm development.