Carla Pruzzo

Publications of Carla Pruzzo

• Characterization of Fluoroquinolone-Resistant Escherichia coli Causing Septicemic Colibacillosis in Calves in Italy: Emergence of a Multiresistant O78 Clonal Group.

  Authors: Anna Marchese, Erika Coppo, Ramona Barbieri, Simona Zoppi, Carla Pruzzo, Francesca Rossi, Stefania Bergagna, Alessandro Dondo, Eugenio Debbia

  Microbial drug resistance (Larchmont, N.Y.). 02/2012; 18(1):94-9.

  An increased incidence of enrofloxacin-resistant Escherichia coli associated with septicemic colibacillosis in calves was observed recently in northern Italy. The aim of this study was to investigateAn increased incidence of enrofloxacin-resistant Escherichia coli associated with septicemic colibacillosis in calves was observed recently in northern Italy. The aim of this study was to investigate this phenomenon. A total of 47 consecutive E. coli isolates exhibiting reduced susceptibility to enrofloxacin (intermediately resistant or resistant) causing septicemic colibacillosis in calves from 45 large-scale farms during 2006-2008, were studied. Phylogenetic group, antimicrobial agents susceptibility, and O serogroup were determined with randomly amplified polymorphic DNA (RAPD) and pulsed-field gel electrophoresis (PFGE) typing, providing additional discrimination. All of the microorganisms carried resistance to two or more additional drugs, with the pattern fluoroquinolone-ampicillin-co-trimoxazole-tetracycline-gentamicin-thiamphenicol being the most represented (18/47; 38.3%). Plasmid-mediated extended-spectrum and AmpC β-lactamases and plasmid-mediated fluoroquinolone resistance genetic determinants were not detected. Third-generation cephalosporins emerged as the most active antimicrobial agents tested (97.9% of susceptible strains). Overall, 37 different RAPD profiles and 18 different O serogroups could be distinguished among the typeable strains, indicating a substantial heterogeneity and suggesting the occurrence of several independent selection events. However, approximately one-fourth (11/47) of the strains belonged to serogroup O78, and PFGE revealed that the great majority (7/11) of these were clonally related, indicating the selection of a O78 clonal group. This is the first report investigating the molecular epidemiology of fluoroquinolone-resistant E. coli in calves and describing the emergence of a fluoroquinolone-resistant E. coli clonal group in these animals.

• Functional foods and strategies contrasting bacterial adhesion.

  Authors: Caterina Signoretto, Pietro Canepari, Monica Stauder, Luigi Vezzulli, Carla Pruzzo

  Current opinion in biotechnology. 09/2011;

  Antibacterial strategies targeting bacterial adhesion to substrates are considered a valuable alternative to traditional antibiotic therapy, in view of the great advantage they bring in combating theAntibacterial strategies targeting bacterial adhesion to substrates are considered a valuable alternative to traditional antibiotic therapy, in view of the great advantage they bring in combating the infectious process at the very early stage without selecting for drug resistant cells. Amongst bioactive compounds with activity against bacterial adhesion, several are found in natural food and beverages, such as cranberry, tea, coffee, wine and milk. For the analysis of their anti-infective potential, successful experimental models can be conducted using different substrates from the oral cavity. Studies conducted so far in this field allowed the discovery of a variety of anti-adhesive fractions and compounds proven to be effective against bacterial traits involved in the development of oral pathologies such as caries and gingivitis/periodontitis. Discovering new anti-adhesive compounds from natural products, unravelling and testing their prophylactic and therapeutic values, and improving their use in the general population are promising new frontiers in the global fight against human infectious diseases.

• Long-term effects of ocean warming on the prokaryotic community: evidence from the vibrios.

  Authors: Luigi Vezzulli, Ingrid Brettar, Elisabetta Pezzati, Philip C Reid, Rita R Colwell, Manfred G Höfle, Carla Pruzzo

  The ISME journal. 07/2011; 6(1):21-30.

  The long-term effects of ocean warming on prokaryotic communities are unknown because of lack of historical data. We overcame this gap by applying a retrospective molecular analysis to the bacterialThe long-term effects of ocean warming on prokaryotic communities are unknown because of lack of historical data. We overcame this gap by applying a retrospective molecular analysis to the bacterial community on formalin-fixed samples from the historical Continuous Plankton Recorder archive, which is one of the longest and most geographically extensive collections of marine biological samples in the world. We showed that during the last half century, ubiquitous marine bacteria of the Vibrio genus, including Vibrio cholerae, increased in dominance within the plankton-associated bacterial community of the North Sea, where an unprecedented increase in bathing infections related to these bacteria was recently reported. Among environmental variables, increased sea surface temperature explained 45% of the variance in Vibrio data, supporting the view that ocean warming is favouring the spread of vibrios and may be the cause of the globally increasing trend in their associated diseases.

• Effects of fruit and vegetable low molecular mass fractions on gene expression in gingival cells challenged with Prevotella intermedia and Actinomyces naeslundii.

  Authors: Laura Canesi, Cristina Borghi, Monica Stauder, Peter Lingström, Adele Papetti, Jonathan Pratten, Caterina Signoretto, David A Spratt, Mike Wilson, Egija Zaura, Carla Pruzzo

  Journal of biomedicine & biotechnology. 01/2011; 2011:230630.

  Low molecular mass (LMM) fractions obtained from extracts of raspberry, red chicory, and Shiitake mushrooms have been shown to be an useful source of specific antibacterial,Low molecular mass (LMM) fractions obtained from extracts of raspberry, red chicory, and Shiitake mushrooms have been shown to be an useful source of specific antibacterial, antiadhesion/coaggregation, and antibiofilm agent(s) that might be used for protection towards caries and gingivitis. In this paper, the effects of such LMM fractions on human gingival KB cells exposed to the periodontal pathogens Prevotella intermedia and Actinomyces naeslundii were evaluated. Expression of cytokeratin 18 (CK18) and β4 integrin (β4INT) genes, that are involved in cell proliferation/differentiation and adhesion, and of the antimicrobial peptide β2 defensin (HβD2) in KB cells was increased upon exposure to either live or heat-killed bacteria. All LMM fractions tested prevented or reduced the induction of gene expression by P. intermedia and A. naeslundii depending on the experimental conditions. Overall, the results suggested that LMM fractions could modulate the effects of bacteria associated with periodontal disease in gingival cells.

• Antiadhesion and antibiofilm activities of high molecular weight coffee components against Streptococcus mutans.

  Authors: Monica Stauder, Adele Papetti, Dora Mascherpa, Anna Maria Schito, Gabriella Gazzani, Carla Pruzzo, Maria Daglia

  Journal of agricultural and food chemistry. 11/2010; 58(22):11662-6.

  In previous studies we demonstrated that green and roasted coffee contains low molecular weight (LMW) compounds capable of inhibiting the ability of Streptococcus mutans, the major causative agent ofIn previous studies we demonstrated that green and roasted coffee contains low molecular weight (LMW) compounds capable of inhibiting the ability of Streptococcus mutans, the major causative agent of human dental caries, to adhere to hydroxyapatite (HA) beads. This study addressed the ability of the whole high molecular weight coffee fraction (cHMW) and of its melanoidin and non-melanoidin components (GFC1-5), applied at concentrations that occur in coffee beverages, to (i) inhibit S. mutans growth; (ii) affect S. mutans sucrose-dependent adhesion to and detachment from saliva-coated HA beads (sHA); and (iii) inhibit biofilm development on microtiter plates. The results indicated that only cHMW is endowed with antimicrobial activity. The cHMW fraction and each of the five GFC components inhibited S. mutans adhesion, the strongest effect being exerted by cHMW (91%) and GFC1 (88%). S. mutans detachment from sHA was four times greater (∼20%) with cHMW and the GFC1 and GFC4 melanoidins than with controls. Finally, biofilm production by S. mutans was completely abolished by cHMW and was reduced by 20% by the melanoidin components GFC2 and GFC4 and by the non-melanoidin component GFC5 compared with controls. Altogether these findings show that coffee beverage contains both LMW compounds and HMW melanoidin and non-melanoidin components with a strong ability to interfere in vitro with the S. mutans traits relevant for cariogenesis.

• Inhibitory activity by barley coffee components towards Streptococcus mutans biofilm.

  Authors: Monica Stauder, Adele Papetti, Maria Daglia, Luigi Vezzulli, Gabriella Gazzani, Pietro E Varaldo, Carla Pruzzo

  Current microbiology. 04/2010; 61(5):417-21.

  It was shown that barley coffee (BC) interferes with Streptococcus mutans adsorption to hydroxyapatite. After BC component fractionation by dialysis and gel filtration chromatography (GFC), it wasIt was shown that barley coffee (BC) interferes with Streptococcus mutans adsorption to hydroxyapatite. After BC component fractionation by dialysis and gel filtration chromatography (GFC), it was found that the low molecular mass (<1,000 Da) fraction (LMM fraction) containing polyphenols, zinc and fluoride ions and, above all, a high molecular mass (HMM > 1,000 kDa) melanoidin fraction display strong anti-adhesive properties towards S. mutans. In this study, we have further examined the potential of BC, BC LMM fraction and BC HMM melanoidin fraction as caries controlling agents by evaluating their anti-biofilm activity.The effects of BC and BC fractions on biofilm formation by S. mutans ATCC 25175 and its detachment from pre-developed biofilms were evaluated by microtiter plate assay. It was found that BC and its fractions, at concentrations ranging from 60 to 15 mg ml(-1) that are devoid of antimicrobial activity, inhibited S. mutans biofilm formation. An increase of S. mutans ATCC 25175 detachment from 24 h developed biofilm was observed at the highest tested concentrations. Interestingly, BC and BC fractions also showed anti-biofilm activity towards a variety of S. mutans clinical strains isolated from saliva, plaque and caries lesions of adult donors. In general, the HMM melanoidin fraction was more active than the LMM fraction. These findings, classifying BC LMM fraction and BC HMM melanoidin fractions as natural anti-biofilm agents, represent the basis for studying their possible use as anti-caries agents.

• Vibrio infections triggering mass mortality events in a warming Mediterranean Sea.

  Authors: Luigi Vezzulli, Monica Previati, Carla Pruzzo, Anna Marchese, David G Bourne, Carlo Cerrano

  Environmental microbiology. 03/2010; 12(7):2007-19.

  Mass mortality events of benthic invertebrates in the temperate north-western (NW) Mediterranean Sea have been observed in recent seasons. A 16 month in situ study in the Ligurian Sea (NWMass mortality events of benthic invertebrates in the temperate north-western (NW) Mediterranean Sea have been observed in recent seasons. A 16 month in situ study in the Ligurian Sea (NW Mediterranean Sea) demonstrated that the occurrence of Paramuricea clavata mortality episodes were concomitant to a condition of prolonged high sea surface temperatures, low chlorophyll concentrations and the presence of culturable Vibrio spp. in seawater. The occurrence of Vibrio spp. at the seasonal scale was correlated with temperature; with few vibrios retrieved on specific media when the temperature dropped below 18 degrees C and a sharp increase of vibrios abundance (up to 3.4 x 10(4) MPN l(-1)) when the temperature was greater than or equal to 22 degrees C. Phylogenetic and phenotypic analysis of Vibrio isolates associated with healthy and diseased P. clavata colonies collected during a mortality episode showed that these bacteria were significantly more abundant in diseased than in healthy corals and were related to the V. harveyi, V. splendidus and V. coralliilyticus groups, the latter only identified in diseased organisms. Inoculation of bacterial isolates from these groups onto healthy P. clavata in aquaria caused disease signs and death in a range of Vibrio concentrations, temperature values and trophic conditions consistent with those recorded in the field. It is concluded that Vibrio infections may act as an additional triggering mechanism of mass mortality events in the coastal Mediterranean Sea and that their occurrence is climate-linked. Predicted global warming leading to long-lasting hot summer periods together with stratification resulting in energetic constraints represent a major threat to the survival of benthic invertebrates in the temperate NW Mediterranean Sea due to potential disease outbreak associated with Vibrio pathogens.

• Benthic ecology of Vibrio spp. and pathogenic Vibrio species in a coastal Mediterranean environment (La Spezia Gulf, Italy).

  Authors: Luigi Vezzulli, Elisabetta Pezzati, Mariapaola Moreno, Mauro Fabiano, Luigi Pane, Carla Pruzzo

  Microbial ecology. 07/2009;

  We carried out a 16-month in situ study to investigate the ecology of Vibrio spp. and pathogenic Vibrio species in coastal sediments of the Mediterranean Sea, employing multiple-regression analysisWe carried out a 16-month in situ study to investigate the ecology of Vibrio spp. and pathogenic Vibrio species in coastal sediments of the Mediterranean Sea, employing multiple-regression analysis to reveal the major environmental factors controlling their occurrence in the benthic environment. In addition, association between vibrios and sediment-inhabiting meiofauna, which is a major component of benthic ecosystems, was investigated. Culturable and total Vibrio spp. estimates by most-probable-number technique coupled with standard polymerase chain reaction (PCR) and real-time PCR methods, respectively, were at least one order of magnitude higher in sediment than in seawater. In addition, potential human pathogenic species Vibrio cholerae, Vibrio vulnificus and Vibrio parahaemolyticus occurred in the sediment with V. parahaemolyticus being the most frequently found. In the pelagic environment, 60% of total variance in culturable Vibrio data was explained by sea surface temperature (40%), salinity (13%) and organic matter concentration (7%). In the benthic environment, sea surface temperature was the only factor that significantly affected culturable Vibrio occurrence although it explained only 25% of total variance, suggesting that additional unexplored factors may play a role as well. No correlation was found between culturable Vibrio spp. concentrations and the abundance of harpacticoid copepods in the sediment whilst a negative correlation was found between Vibrio spp. and nematode abundance which accounted for almost 90% of the total meiofaunal density. Taxonomic analysis revealed that selective bacterial feeders accounted for nearly 50% of the total nematode community and included genera such as Terschellingia, Molgolaimus and Halalaimus, suggesting that top-down control by nematode grazing may be an important factor affecting Vibrio occurrence in these sediments. It is concluded that the benthic marine environment may function as a reservoir of Vibrio spp. and potential pathogenic vibrios whose ecological features appeared substantially different from the ones recognised in the pelagic environment.

• Dual role colonization factors connecting Vibrio cholerae's lifestyles in human and aquatic environments open new perspectives for combating infectious diseases.

  Authors: Luigi Vezzulli, Carlos A Guzmán, Rita R Colwell, Carla Pruzzo

  Current opinion in biotechnology. 07/2008; 19(3):254-9.

  Vibrio cholerae exhibits two distinctive lifestyles, one inside the milieu of the human intestine and the other in the aquatic environment. Recently, the existence of V. cholerae ligands involved inVibrio cholerae exhibits two distinctive lifestyles, one inside the milieu of the human intestine and the other in the aquatic environment. Recently, the existence of V. cholerae ligands involved in colonization of both human intestine and environmental chitin surfaces via the same binding specificity has been shown. Such molecules, here named 'dual role colonization factors (DRCFs)', are example of a tight connection between the two V. cholerae's lifestyles. It is suggested that DRCFs and, more generally, bacterial factors and pathways having roles in pathogenesis and in the out of the human body life may be promising targets for development of novel prophylactic or therapeutic interventions that may also affect V. cholerae fitness in its environmental reservoirs.

• Global impact of Vibrio cholerae interactions with chitin.

  Authors: Carla Pruzzo, Luigi Vezzulli, Rita R Colwell

  Environmental microbiology. 07/2008; 10(6):1400-10.

  The interaction of Vibrio cholerae with chitin exemplifies for microbial ecology a successful bacteria-substrate interaction with complex and significant influence on the lifestyle of the bacterium.The interaction of Vibrio cholerae with chitin exemplifies for microbial ecology a successful bacteria-substrate interaction with complex and significant influence on the lifestyle of the bacterium. Chitin is one of the most abundant polymers on earth and possibly the most abundant in the aquatic environment, where its association with V. cholerae has provided the microorganism with a number of advantages, including food availability, adaptation to environmental nutrient gradients, tolerance to stress and protection from predators. Emergent properties of V. cholerae-chitin interactions occur at multiple hierarchical levels in the environment and include cell metabolic and physiological responses e.g. chemotaxis, cell multiplication, induction of competence, biofilm formation, commensal and symbiotic relationship with higher organisms, cycling of nutrients, and pathogenicity for humans and aquatic animals. As factors mediating virulence of V. cholerae for humans and aquatic animals derive from mechanisms of adaptation to its environment, at different levels of hierarchical scale, V. cholerae interactions with chitin represent a useful model for examination of the role of primary habitat selection in the development of traits that have been identified as virulence factors in human disease.

• Human pathogens in water: insights into their biology and detection.

  Authors: Pietro Canepari, Carla Pruzzo

  Current opinion in biotechnology. 07/2008; 19(3):241-3.

• Vibrios in association with sedimentary crustaceans in three beaches of the northern Adriatic Sea (Italy).

  Authors: A Covazzi Harriague, Marco Di Brino, Massimiliano Zampini, Giancarlo Albertelli, Carla Pruzzo, Cristina Misic

  Marine pollution bulletin. 04/2008; 56(3):574-9.

  In the marine environment, vibrios adhere to a number of substrates including chitin-rich organisms such as crustaceans. Their wide diffusion in coastal waters and pathogenic potential requireIn the marine environment, vibrios adhere to a number of substrates including chitin-rich organisms such as crustaceans. Their wide diffusion in coastal waters and pathogenic potential require knowledge of the lifestyle and environmental reservoirs of these bacteria. To test the presence of culturable vibrios in coastal areas and their association with benthic crustaceans, vibrios were isolated from water, sediments and crustaceans (copepods and anphipods) at three stations placed in front of heavily used tourist beaches of the Adriatic Sea. We observed significant correlations between vibrios and temperature. Benthic and planktonic copepods harboured vibrios in summer, while benthic amphipods harboured these bacteria in spring and autumn. Vibrio alginolyticus and Vibrio parahaemolyticus strains gave positive results using primers for Vibrio cholerae toxR and toxS. Sedimentary crustaceans may extend Vibrio persistence in seawater and may represent an additional aquatic reservoir of these bacteria.

• Co-transfer of vanA and aggregation substance genes from Enterococcus faecalis isolates in intra- and interspecies matings.

  Authors: Claudia Paoletti, Gessica Foglia, Maria Stella Princivalli, Gloria Magi, Emilio Guaglianone, Gianfranco Donelli, Carla Pruzzo, Francesca Biavasco, Bruna Facinelli

  The Journal of antimicrobial chemotherapy. 06/2007; 59(5):1005-9.

  OBJECTIVES: The study was undertaken to investigate vancomycin-resistant (vanA) Enterococcus faecalis isolates carrying aggregation substance (AS) gene(s) for their ability to co-transfer vanA and ASOBJECTIVES: The study was undertaken to investigate vancomycin-resistant (vanA) Enterococcus faecalis isolates carrying aggregation substance (AS) gene(s) for their ability to co-transfer vanA and AS genes. METHODS: Six vanA clumping-positive E. faecalis isolates (five human and one food sample) carrying one or more AS genes (prgB, asa1, asa373) were analysed for co-transfer of vanA and AS genes to E. faecalis JH2-2 and Enterococcus faecium 64/3. RESULTS: E. faecalis isolates harboured one or multiple plasmids carrying vanA, one or more AS gene(s) or both. vanA was transferred to JH2-2 (frequencies of 10(-3)-10(-6)) from all donors and to 64/3 (10(- 6)-10(- 8)) only from donors from humans. AS genes were detected in 51/60 (85%) of JH2-2 and in 20/50 (40%) of 64/3 vanA transconjugants (prgB, asa1, asa373 or prgB asa373), of which a total of 53.6% were clumping-positive. The plasmid content of JH2-2 transconjugants from the same donor was either identical to that of the donor or it was completely different, suggesting different mechanisms for co-transfer (location on the same pheromone plasmid, mobilization of vanA plasmids by the pheromone-inducible conjugation system, rearrangement of plasmid content during matings). After induction with pheromones, a marked increase in adhesion to Caco-2 cells was observed in four isolates and in some JH2-2 transconjugants, all clumping-positive. CONCLUSIONS: Findings suggest that co-transfer of vanA and AS genes may be a common feature of E. faecalis isolates. Since AS is recognized as a virulence factor, this feature might contribute to the emergence of strains with enhanced ability to cause infection and disease in humans.

• Effect of barley coffee on the adhesive properties of oral streptococci.

  Authors: Adele Papetti, Carla Pruzzo, Maria Daglia, Pietro Grisoli, Alessandro Bacciaglia, Barbara Repetto, Cesare Dacarro, Gabriella Gazzani

  Journal of agricultural and food chemistry. 02/2007; 55(2):278-84.

  Some beverages and foods protect tooth surfaces against Streptococcus mutans colonization. Adhesion of S. mutans is a crucial step in the initiation and development of dental caries. In this study,Some beverages and foods protect tooth surfaces against Streptococcus mutans colonization. Adhesion of S. mutans is a crucial step in the initiation and development of dental caries. In this study, we showed that barley coffee (BC), a beverage made from roasted barley, interferes with S. mutans adsorption to hydroxyapatite (HA), and we identified its antiadhesive components. The effects of sublethal concentrations (sub-MICs) of BC on the adhesion of S. mutans to saliva-coated HA beads were assessed using three experimental approaches: (A) Beads were pretreated with BC before adding bacteria, (B) BC and bacteria were added to the beads simultaneously, and (C) streptococci grown in the presence of sub-MICs of BC were added to the beads. All treatments induced variable but significant inhibition of S. mutans sucrose-dependent and -independent adherence to HA. Similar results were obtained with other oral streptococci. BC components were fractioned by dialysis and gel filtration chromatography; the <1000 Da molecular mass (MM) fraction, which contains polyphenols, zinc, and fluoride ions, and the >1000 kDa MM fraction, which consists of a potent brown antioxidant, melanoidin, both displayed antiadhesive properties. High-MM melanoidin was not detected in unroasted barley, indicating that it forms during the roasting process. Results suggest that BC consumption may influence the colonization of tooth surfaces by cariogenic bacteria.

• Detection of free-living and plankton-bound vibrios in coastal waters of the Adriatic Sea (Italy) and study of their pathogenicity-associated properties.

  Authors: Wally Baffone, Renato Tarsi, Luigi Pane, Raffaella Campana, Barbara Repetto, Gian Luigi Mariottini, Carla Pruzzo

  Environmental microbiology. 08/2006; 8(7):1299-305.

  Culturable vibrios were isolated from water and plankton fractions collected during an 18-month sampling study performed along the north-central coast of the Adriatic Sea (Italy). Unculturable VibrioCulturable vibrios were isolated from water and plankton fractions collected during an 18-month sampling study performed along the north-central coast of the Adriatic Sea (Italy). Unculturable Vibrio vulnificus and V. parahaemolyticus were detected in plankton fractions by polymerase chain reaction amplification of DNA sequences for cytotoxin-haemolysin and thermolabile haemolysin respectively. The presence of V. parahaemolyticus, V. vulnificus and V. cholerae virulence genes and the expression of pathogenicity-associated traits were analysed in all isolates. The results showed the spreading of these properties among the environmental isolates and confirm the need of both monitoring the presence of vibrios in coastal areas and studying their pathogenicity potential in order to properly protect human health.

• Persistence of vibrios in marine bivalves: the role of interactions with haemolymph components.

  Authors: Carla Pruzzo, Gabriella Gallo, Laura Canesi

  Environmental microbiology. 07/2005; 7(6):761-72.

  Marine bivalves are widespread in coastal environments and, due to their filter-feeding habit, they can accumulate large numbers of bacteria thus acting as passive carriers of human pathogens.Marine bivalves are widespread in coastal environments and, due to their filter-feeding habit, they can accumulate large numbers of bacteria thus acting as passive carriers of human pathogens. Bivalves possess both humoral and cellular defence mechanisms that operate in a co-ordinated way to kill and eliminate infecting bacteria. Vibrio species are very abundant in coastal waters and are commonly isolated from edible bivalves tissues where they can persist after depuration processes in controlled waters. Such observations indicate that vibrios are regular components of bivalve microflora and that the molluscs can represent an important ecological niche for these bacteria. Here we tried to summarize data on the interactions between vibrios and bivalve haemolymph; the available evidence supports the hypothesis that persistence of bacteria in bivalve tissues depends, at least in part, on their sensitivity to the bactericidal activity of the haemolymph. Results obtained with an in vitro model of Vibrio cholerae challenged against Mytilus galloprovincialis haemocytes indicate that bacterial surface components, soluble haemolymph factors and the signalling pathways of the haemocyte host are involved in determining the result of vibrio-haemolymph interactions.

• Persistence of Enterococcus faecalis in aquatic environments via surface interactions with copepods.

  Authors: Caterina Signoretto, Gloria Burlacchini, Carla Pruzzo, Pietro Canepari

  Applied and environmental microbiology. 06/2005; 71(5):2756-61.

  Several human pathogens and fecal-pollution indicators may persist as viable organisms in natural environments, owing to their ability to activate different types of survival strategies. TheseSeveral human pathogens and fecal-pollution indicators may persist as viable organisms in natural environments, owing to their ability to activate different types of survival strategies. These strategies include adhesion on both abiotic and biotic surfaces and the entrance to the so-called viable but nonculturable (VBNC) state. In an 18-month survey for the detection of enterococci in both lake water and seawater, C. Signoretto et al. (Appl. Environ. Microbiol. 70:6892-6896, 2004) have shown that Enterococcus faecalis was detected mostly bound to plankton and in the VBNC state. In the present study, we show that in vitro adhesion of E. faecalis to copepods accelerated the entry of cells into the VBNC state relative to that of planktonic bacteria. VBNC E. faecalis cells maintained their adhesive properties to copepods and chitin (the main component of the copepod carapace), though to a reduced extent in comparison with growing cells. Sugar competition experiments showed interference with adhesion to both copepods and chitin by GlcNAc and only to copepods by D-mannose. Four enterococcal cell wall proteins present in both growing and VBNC cells and lipoteichoic acid were shown to be capable of binding chitin. The results indicate that copepods may represent an additional environmental reservoir of enterococci, thus suggesting the advisability of redesigning the protocols currently used for microbial detection during the evaluation of the microbiological quality of environmental samples.

• Interactions between Mytilus haemocytes and different strains of Escherichia coli and Vibrio cholerae O1 El Tor: role of kinase-mediated signalling.

  Authors: Laura Canesi, Michele Betti, Caterina Ciacci, Lucia Cecilia Lorusso, Gabriella Gallo, Carla Pruzzo

  Cellular microbiology. 06/2005; 7(5):667-74.

  Marine bivalves accumulate large amounts of bacteria from the environment (mainly Vibrionaceae and coliforms). Although persistence of different bacteria in bivalve tissues largely depends on theirMarine bivalves accumulate large amounts of bacteria from the environment (mainly Vibrionaceae and coliforms). Although persistence of different bacteria in bivalve tissues largely depends on their sensitivity to the bactericidal activity of circulating haemocytes and haemolymph soluble factors, the mechanisms involved in bacteria-host cell interactions in these invertebrates are largely unknown. In the mussel Mytilus, differences in interactions between haemocytes and different Escherichia coli and Vibrio cholerae strains [E. coli MG155, a wild-type strain carrying type 1 fimbriae, and its unfimbriated derivative, AAEC072 Deltafim; V. cholerae O1 El Tor biotype strain N16961, carrying the mannose-sensitive haemagglutinin (MSHA), and its MSHA mutant] lead to differences in bactericidal activity in the presence of serum. Here we show that different bacteria induced distinct patterns of phosphorylation of mitogen-activated protein kinases (MAPKs), in particular of the stress-activated MAPKs involved in the immune response. Differences in phosphorylation of PKC-like proteins were also observed. The results support the hypothesis that, like in mammalian host cells, different bacteria can modulate the signalling pathways of mussel haemocytes. The lower anti-bacterial activity towards the mutant E. coli strain and wild-type V. cholerae compared with wild E. coli may result from a reduced capacity of activating MAPKs. Moreover, the mutant V. cholerae strain that was the most resistant to the haemocyte bactericidal activity induced downregulation of cell signalling and showed the strongest effect on lysosomal membrane stability, evaluated as a marker of bivalve cell stress. These data suggest that certain bacteria could evade the bactericidal activity of mussel haemocytes through disruption of the host signalling pathways.

• Vibrio cholerae persistence in aquatic environments and colonization of intestinal cells: involvement of a common adhesion mechanism.

  Authors: Massimiliano Zampini, Carla Pruzzo, Vijay P Bondre, Renato Tarsi, Mariangela Cosmo, Alessandro Bacciaglia, Arvind Chhabra, Renjana Srivastava, Brahm S Srivastava

  FEMS microbiology letters. 04/2005; 244(2):267-73.

  Forty-one Tnpho A mutants of Vibrio cholerae O1 classical strain CD81 were analyzed for their ability to interact with chitin particles, Tigriopus fulvus copepods and the Intestine 407 cell lineForty-one Tnpho A mutants of Vibrio cholerae O1 classical strain CD81 were analyzed for their ability to interact with chitin particles, Tigriopus fulvus copepods and the Intestine 407 cell line compared to the parent strain. Thirteen mutants were less adhesive than CD81; in particular, T21, T33 and T87 were less adhesive towards all substrates and insensitive to inhibition by N-acetyl glucosamine (GlcNAc). By SDS-PAGE analysis of sarkosyl-insoluble membrane proteins (siMPs) isolated from mutants and parent, it was found that a 53 kDa siMP is missing in T21, T33 and T87 mutants. It is hypothesized that this protein might have the function to mediate adherence to GlcNAc-containing substrates both in the aquatic environment and in human intestine.

• Adhesion of Enterococcus faecalis in the nonculturable state to plankton is the main mechanism responsible for persistence of this bacterium in both lake and seawater.

  Authors: Caterina Signoretto, Gloria Burlacchini, Maria del Mar Lleò, Carla Pruzzo, Massimiliano Zampini, Luigi Pane, Giorgio Franzini, Pietro Canepari

  Applied and environmental microbiology. 12/2004; 70(11):6892-6.

  The presence of enterococci in lake and seawater in an 18-month survey comparing molecular (PCR and quantitative PCR) and culture methods was evaluated, as well as the possibility that zooplanktonThe presence of enterococci in lake and seawater in an 18-month survey comparing molecular (PCR and quantitative PCR) and culture methods was evaluated, as well as the possibility that zooplankton could act as reservoirs for enterococci. Samples of both water and zooplankton were collected monthly from a Lake Garda site and an Adriatic Sea site. In lake water, the positive samples numbered 13 of 54 (24%) by culture and 32 of 54 (59%) when PCR was applied. In seawater, they numbered 0 of 51 by culture and 18 of 51 (35%) by PCR. Enterococci were found either totally bound to plankton or totally in water, depending on the presence or absence of plankton, respectively. These results clearly indicate that the PCR assay is a powerful tool for detecting fecal indicators and pathogens in the environment, thus providing a much more sensitive method than culture.