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Access to clean water and adequate sanitation is crucial for maintaining good health; however, numerous individuals face a lack access to clean water. The study was to investigation the physicochemical, assessment of coliform bacteria, phenotypic virulence characteristics and antibiotic susceptibility pattern of the identified organisms from borehole and well water samples. The result obtained showed o that pH ranged from 6.06 - 7.59, while temperature (25.3 - 29.4 °C), electrical conductivity (13 – 159 µS/cm), turbidity (0.21 – 1.83 NTU), total suspended solid (0.23 – 0.98 mg/ml), Alkalinity (0.12 – 0.50), Hardness (1.05 – 2.95 mg/ml), Phosphate (0.1 – 1.99 mg/L), Nitrate (0.03 – 1.05 mg/L), and Sulphate (0.12 – 1.0 mg/L) were within acceptable range delineated by World Health Organization for drinking water. The heterotrophic bacterial count range from 138.00±2.83CFU/100ml to 267.50±17.68CFU/100ml, coliform count ranged from 11.00±1.41 CFU/100ml to 147.50±7.78 and the counts were also found to be higher than the values stipulated by World Health Organization guidelines. The bacteria identified were Bacillus cereus, Escherichia coli, Pseudomonas aeruginosa, Serratia marcescens and Enterobacter cloacae. Bacillus (37.50%) and Escherichia (20.83%) were the most frequently occurring bacterial isolates from water samples in the study. The phenotypic virulence properties of the bacterial isolates showed that they had at least one virulence determinants. The antibacterial sensitivity testing revealed that all isolates were susceptible to Ciprofloxacin (5mcg), with a MAR index greater than 0.2 indicating that the isolates were all pathogens of public health importance. This study therefore highlights the need for continuous monitoring and quality assessment of drinking water sources. [ABSTRACT FROM AUTHOR]

The quantity of seafood imported and produced by domestic aquaculture farming has increased. Recently, it has been reported that multidrug-resistant (MDR) Salmonella Typhimurium may be associated with seafood. However, information is limited to the antimicrobial resistance, virulence properties, and genetic diversity of S. Typhimurium recovered from imported and domestic seafood. This study investigated the antimicrobial resistance, virulence properties, and genetic diversity of S. Typhimurium isolated from domestic and imported catfish, shrimp, and tilapia. A total of 127 isolates were tested for the presence of multidrug-resistance (MDR), virulence genes (invA, pagC, spvC, spvR), and genetic diversity using the Sensititre micro-broth dilution method, PCR, and pulsed-field gel electrophoresis (PFGE), respectively. All isolates were uniformly susceptible to six (amoxicillin/clavulanic acid, ceftiofur, ceftriaxone, imipenem, nitrofurantoin, and trimethoprim/sulfamethoxazole) of the 17 tested antimicrobials and genetically diverse. Fifty-three percent of the Salmonella isolates were resistant to at least one antimicrobial and 49% were multidrug resistant. Ninety-five percent of the isolates possessed the invA gene, 67% pagC, and 43% for both spvC, and spvR. The results suggest that S. Typhimurium recovered from seafood is frequently MDR, virulent, and have the ability to cause salmonellosis. [ABSTRACT FROM AUTHOR]

The quantity of seafood imported and produced by domestic aquaculture farming has increased. Recently, it has been reported that multidrug-resistant (MDR) Salmonella Typhimurium may be associated with seafood. However, information is limited to the antimicrobial resistance, virulence properties, and genetic diversity of S. Typhimurium recovered from imported and domestic seafood. This study investigated the antimicrobial resistance, virulence properties, and genetic diversity of S. Typhimurium isolated from domestic and imported catfish, shrimp, and tilapia. A total of 127 isolates were tested for the presence of multidrug-resistance (MDR), virulence genes (invA, pagC, spvC, spvR), and genetic diversity using the Sensititre micro-broth dilution method, PCR, and pulsed-field gel electrophoresis (PFGE), respectively. All isolates were uniformly susceptible to six (amoxicillin/clavulanic acid, ceftiofur, ceftriaxone, imipenem, nitrofurantoin, and trimethoprim/sulfamethoxazole) of the 17 tested antimicrobials and genetically diverse. Fifty-three percent of the Salmonella isolates were resistant to at least one antimicrobial and 49% were multidrug resistant. Ninety-five percent of the isolates possessed the invA gene, 67% pagC, and 43% for both spvC, and spvR. The results suggest that S. Typhimurium recovered from seafood is frequently MDR, virulent, and have the ability to cause salmonellosis.

The study provides data on antibiotic resistance as well as the virulence characteristics of Aeromonas caviae isolated from raw and treated wastewater. The isolates were identified as A. caviae by 16S rRNA gene sequencing. In the analyzed strains, high frequency for the following genes was observed: aac(6′)-Ib-cr, qnrB, and qnrD. The presence of qnrA and ogxB genes was not found in any strain. The higher frequency of the investigated genes was observed in strains from raw wastewater (RW). The strains of A. caviae showed multiple antibiotic resistance evaluated by the disk diffusion method. Multiple antibiotic resistance indices ranged from 0.36 to 0.69. Susceptibility to six heavy metals (Cd+2, Zn+2, Cu+2, Co+2, Mn+2, and Ni+2) was recorded for all the isolates. The order of metal resistance of A. caviae was Co > Cu > Zn > Cd > Ni > Mn. All the strains of A. caviae showed β-hemolytic activity. Enzymes of amylase, cellulase, and lipase were produced by all isolates. Only the strains from RW had the ability to form biofilms and showed motility. The obtained results indicate that wastewater is a potential source and/or reservoir of virulent and multidrug-resistant A. caviae as "high-risk isolates." [ABSTRACT FROM AUTHOR]

Escherichia coli is a normal inhabitant of the enteric microflora of human and animal. Intestinal and extra-intestinal infections caused by E. coli in mammals are characterized by the presence of diversity of virulence factors. In addition it can be isolated from environment surrounding human and animal farms. E. coli is the main environmental pathogen causing clinical mastitis in dairy cattle. It causes a wide range of disease severity, from changes seen exclusively in milk to severe systemic signs. The severity of clinical mastitis has been conventionally classified into three levels: mild (grade 1), moderate (score 2), and severe (score 3). Recently, reports of cases of bovine mastitis caused by environmental agents have been on the rise, in particular in countries that have succeeded in controlling contagious microorganisms. Unlike enteric and certain extra-enteric conditions in domestic animals and humans, the impact of virulence factors on the occurrence of bovine mastitis due to E. coli, as well as the clinical severity of the cases, is not fully understood. In this regard, the present study reviewed the most relevant virulence factors of E. coli in human and animals, with emphasis in bovine mastitis.

Aeromonas spp. are opportunistic pathogenic bacteria associated with a multitude of diseases in ornamental fish. In this study, virulence properties and antibiotic resistance patterns of 43 Aeromonas strains isolated from 46 zebrafish were investigated. The isolates were identified as Aeromonas veronii biovar veronii (n = 26), A. veronii biovar sobria (n = 3), Aeromonas hydrophila (n = 8), A. caviae (n = 3), Aeromonas enteropelogenes (n = 2) and Aeromonas dhakensis (n = 1) by gyrB gene sequencing. The sequence divergence within and between the species ranged from 0–5·80% and 4·90–8·00%. Each species formed a distinct group in a neighbour‐joining phylogenetic tree. The lipase production, biofilm formation, DNase activity, gelatinase production, caseinase production and β‐hemolysis were phenotypically observed in 34 (79·07%), 33 (74·74%), 30 (69·77%), 25 (58·14%), 22 (51·18%) and 21 (48·84%) isolates. The virulence genes were detected by polymerase chain reaction (PCR) in following frequencies‐ aer (86·05%), hlyA (83·72%), gcaT (83·72%), lip (72·09%), act (67·44%), fla (65·12%), ascV (58·14%), ast (55·81%), ser (41·86%), ahyB (39·53%) and alt (25·58%). Every isolate was resistant to at least four antibiotics in disk diffusion test. The multiple antibiotic resistance (MAR) index values ranged from 0·22–0·50 among the isolates. Our study suggests that zebrafish can be a potential reservoir of virulent and multi‐drug resistant Aeromonas spp. Significance and Impact of the Study: Aeromonas spp. are Gram‐negative and facultative anaerobic bacteria which are ubiquitous in aquatic environments. Virulence properties and antibiotic resistance of ornamental fish‐borne Aeromonas spp. are poorly understood. The virulence factors as well as multiple antibiotic resistance profiles of zebrafish‐borne Aeromonas spp. were characterized for the first time in Korea. Most of the isolates were positive for phenotypic virulence traits and harboured several virulence genes revealing the virulence potential of zebrafish‐borne Aeromonas spp. Additionally, the high multiple antibiotic resistance (MAR) index values displayed by the isolates highlight the necessity of responsible use of antibiotics in the ornamental fish industry. Significance and Impact of the Study: Aeromonas spp. are Gram‐negative and facultative anaerobic bacteria which are ubiquitous in aquatic environments. Virulence properties and antibiotic resistance of ornamental fish‐borne Aeromonas spp. are poorly understood. The virulence factors as well as multiple antibiotic resistance profiles of zebrafish‐borne Aeromonas spp. were characterized for the first time in Korea. Most of the isolates were positive for phenotypic virulence traits and harboured several virulence genes revealing the virulence potential of zebrafish‐borne Aeromonas spp. Additionally, the high multiple antibiotic resistance (MAR) index values displayed by the isolates highlight the necessity of responsible use of antibiotics in the ornamental fish industry. [ABSTRACT FROM AUTHOR]

Cow mastitis caused by Escherichia coli (E. coli) exhibits various local and systemic clinical signs at varying degrees of severity. The aim this study was to elucidate the virulence properties, antibiotic resistance and phylogenetics of 56 E. coli strains. Of all the studied strains, 12 were positive for hemolytic properties and 38 were positive for biofilm production. Additionally, 55 of the strains were positive for multiple resistances in bacteriological tests. PCR analysis revealed that 42 strains carried the traT gene, 20 strains had the shiga toxin gene (stx1-stx2), and 8 strains carried the intimin gene (eae), but all strains were negative for aerobactin gene (aer). All strains encoding shiga toxin genes were also positive for stx1, but only 4 strains were positive for stx2. There were no significant differences in virulence genes between antibiotic-resistant and antibiotic-susceptible strains. The random amplifi ed polymorphic DNA-polymerase chain reaction patterns revealed the existence of 13 main groups with 4 subgroups of E. coli. In this study, E. coli strains causing intramammary infections and originating from various sources might show resistance against common antibiotics. Pathogenity of E. coli that cause clinical mastitis, and prognosis of the infection might be predicted by obtaining the traT gene. Additionally, antibiotic resistance should be investigated at the genomic level to detect the relationship between virulence factors and antibiotic resistance. In field conditions, development of antibiotic resistance is the main cause of mastitis treatment failure. Thus, antibiotic resistance profiles in herds should be monitored and effective antibiotics should be administered

While the influence of water in Helicobacter pylori culturability and membrane integrity has been extensively studied, there are little data concerning the effect of this environment on virulence properties. Therefore, we studied the culturability of water-exposed H. pylori and determined whether there was any relation with the bacterium’s ability to adhere, produce functional components of pathogenicity and induce inflammation and alterations in apoptosis in an experimental model of human gastric epithelial cells. H. pylori partially retained the ability to adhere to epithelial cells even after complete loss of culturability. However, the microorganism is no longer effective in eliciting in vitro host cell inflammation and apoptosis, possibly due to the non-functionality of the cag type IV secretion system. These H. pylori-induced host cell responses, which are lost along with culturability, are known to increase epithelial cell turnover and, consequently, could have a deleterious effect on the initial H. pylori colonisation process. The fact that adhesion is maintained by H. pylori to the detriment of other factors involved in later infection stages appears to point to a modulation of the physiology of the pathogen after water exposure and might provide the microorganism with the necessary means to, at least transiently, colonise the human stomach.

The α subunit (ATP1) is a vital component of mitochondrial complex V which counts for the majority of cellular ATP production in a living organism. Nevertheless, how the α subunit influences other cellular processes such as pathogenicity in Candida albicans remains poorly understood. To address this question, ATP1 mutant (atp1Δ/Δ) and the gene-reconstituted strain (atp11/ATP1) have been constructed in this study and their pathogenicity-related traits are compared to those of wild type (WT). In a murine model of disseminated candidiasis, atp1Δ/Δ infected mice have a significantly higher survival rate and experience a lower fungal burden in tissues. In in vitro studies atp1Δ/Δ lose a capability to damage or destroy macrophages and endothelial cells. Furthermore, atp1Δ/Δ is not able to grow under either glucose-denial conditions or high H2O2 conditions, both of which are associated with the potency of the macrophages to kill C. albicans. Defects in filamentation and biofilm formation may impair the ability of atp1Δ/Δ to penetrate host cells and establish robust colonies in the host tissues. In concert with these pathogenic features, intracellular ATP levels of atp1Δ/Δ can drop to 1/3 of WT level. These results indicate that the α subunit of Complex V play important roles in C. albicans pathogenicity. [ABSTRACT FROM AUTHOR]

Dryopteris crassirhizoma is traditionally used as an herbal remedy for various diseases, and has been identified in a previous study as a potential anti-caries agent. In this study, the effect of a methanol extract of D. crassirhizoma on the viability, growth and virulence properties of Streptococcus mutans, a cariogenic dental pathogen, was investigated. In addition, the phytochemical composition of the extract was analyzed. The extract showed bactericidal and bacteriostatic activity against oral bacteria (MIC and MBC of S. mutans: 62.5 and 250 μg/mL, respectively). At two times the MBC, the extract significantly eliminated S. mutans up to 99.9% after 1 h incubation. The extract also dose-dependently reduced growth rates of S. mutans at sub-MIC levels. Furthermore, at sub-MIC levels, virulence properties (acid production, acid tolerance, glucosyltransferase activity and sucrose-dependent adherence) of S. mutans were also inhibited in a dose-dependent manner. GC-MS analysis revealed the presence of mono and disaccharides (44.9%), fatty acids (12.3%) and sugar alcohols (6.8%) in the extract. These data indicate that the extract might be useful for the control of dental caries.

Escherichia coli strains of nonenteropathogenic serogroups carrying eae but lacking the enteropathogenic E. coli adherence factor plasmid and Shiga toxin DNA probe sequences were isolated from patients (children, adults, and AIDS patients) with and without diarrhea in Brazil. Although diverse in phenotype and genotype, some strains are potentially diarrheagenic.

Abilities to tolerate environmental stresses and to form biofilms on teeth surface are key virulence attributes of Streptococcus mutans, the primary causative agent of human dental caries. ClpP, the chief intracellular protease of S. mutans, along with ATPases degrades altered proteins that might be toxic for bacteria, and thus plays important roles in stress response. To further understand the roles of ClpP in stress response of S. mutans, a ClpP deficient strain was constructed and used for general stress tolerance, autolysis, mutacins production, and virulence assays. Here, we demonstrated that inactivation of ClpP in S. mutans resulted in a sensitive phenotype to several environmental stresses, including acid, cold, thermal, and oxidative stresses. The ClpP deficient strain displayed slow growth rates, poor growth yields, formation of long chains, increased clumping in broth, and reduced capacity to form biofilms in presence of glucose. Mutacins production and autolysis of S. mutans were also impaired by mutation of clpP. Animals study showed that clpP mutation increased virulence of S. mutans but not significant. However, enhanced abilities to survive lethal acid and to form biofilm in sucrose were observed in ClpP deficient strain. Our findings revealed a broad impact of ClpP on several virulence properties of S. mutans and highlighted the relevance of ClpP proteolysis with progression of diseases caused by S. mutans. [ABSTRACT FROM AUTHOR]

Abstract: Aeromonas hydrophila, an inhabitant of aquatic ecosystems found in most parts of the world, has considerable virulence potential. The polymerase chain reaction technique was used to assay for the presence of five virulence factor genes: haemolytic toxins aerA and ahh1, elastase ahyB, the enterotoxin act, and the polar flagella flaA/flaB in the A. hydrophila strain isolated from the River Nile. Drug screening showed high levels of resistance to β-lactam antibiotics and tetracycline. Slime production was determined by the Congo red agar plate test. The isolate produced two restriction enzymes named AehI and AehII which are isoschizomers of XhoI and StuI respectively. The complete nucleotide sequence of the cryptic plasmid pAhy2.5 (2524bp) from this strain was determined. Sequence analysis revealed the presence of two open reading frames (ORFs) encoding putative proteins. The protein coded by ORF1 is homologous with Rep proteins of plasmids belonging to the pC194 family, which are known to replicate by the rolling-circle mechanism. The putative double-strand origin of replication and a region with palindromic sequences that could function as a single-strand origin were detected in pAhy2.5. [Copyright &y& Elsevier]

Abstract: Photobacterium damselae subsp. damselae has been isolated from different outbreaks affecting cultured Sparus aurata and Dicentrarchus labrax. The aim of the present study was to characterize the phenotype and genotype of 12 P. damselae subsp. damselae strains isolated from these outbreaks. The roles of skin mucus in resistance to the initial infection steps have been studied. All tested strains resisted the bactericidal activity of the mucus and showed an ability to adhere to it, but only those showing hemolytic activity were found to be virulent by intraperitoneal injection. Phenotypic and genetic characterization revealed a considerable degree of variability within the subspecies. We found that RAPD-PCR represents a quick tool to generate information on intraspecific differences in environmental strains. We found, that some biotypes are more pathogenic than others, which by doing correlation between adhesion profile, enzymatic and hemolytic activity. [Copyright &y& Elsevier]

Withania somnifera (Ashwagandha) is a plant of the Solanaceae family. It has been widely used as a remedy for a variety of ailments in India and Nepal. The plant has also been used as a controlling agent for dental diseases. The aim of the present study was to evaluate the activity of the methanol extract of W. somnifera against the physiological ability of cariogenic biofilms and to identify the components of the extract. To determine the activity of the extract, assays for sucrose-dependent bacterial adherence, glycolytic acid production, acid tolerance, and extracellular polysaccharide formation were performed using Streptococcus mutans biofilms. The viability change of S. mutans biofilms cells was also determined. A phytochemical analysis of the extract was performed using TLC and LC/MS/MS. The extract showed inhibitory effects on sucrose-dependent bacterial adherence (≥ 100 μg/ml), glycolytic acid production (≥ 300 μg/ml), acid tolerance (≥ 300 μg/ml), and extracellular polysaccharide formation (≥ 300 μg/ml) of S. mutans biofilms. However, the extract did not alter the viability of S. mutans biofilms cells in all concentrations tested. Based on the phytochemical analysis, the activity of the extract may be related to the presence of alkaloids, anthrones, coumarines, anthraquinones, terpenoids, flavonoids, and steroid lactones (withanolide A, withaferin A, withanolide B, withanoside IV, and 12-deoxy withastramonolide). These data indicate that W. somnifera may be a potential agent for restraining the physiological ability of cariogenic biofilms. [ABSTRACT FROM AUTHOR]

The occurrence of the hemolysin genes, tdh and trh, in Vibrio parahaemolyticus strains isolated from environmental samples collected from various exported seafood products comprising of fishes and shellfish ( Mytilus edulis and Crassostrea gigas) or seawater, was studied. Eight strains were confirmed as V. parahaemolyticus by toxR -based polymerase chain reaction and only one strain out of these 8 strains was positive for tdh and trh genes. Toxigenic V. parahaemolyticus isolates are present in Tunisian coastal areas and they may also be present in Tunisian exported seafood products. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this study was to evaluate the effect of the methanol extract of Withania somnifera (MEW) on the growth and virulence properties of Streptococcus mutans and Streptococcus sobrinus at sub-minimum inhibitory concentration (MIC) levels and to identify the main components of MEW. First, antibacterial activity of MEW against oral bacteria was determined using a micro-dilution method. Then, the effect of MEW on the growth of S. mutans and S. sobrinus was investigated at sub-MIC levels. To test the effect of MEW on the virulence properties of S. mutans and S. sobrinus, assays for acid production, acid tolerance, and biofilm formation were performed at sub-MIC levels. A GC–MS analysis for the main components of MEW was also carried out. MEW showed a broad antibacterial range against oral bacteria (MIC: 0.125–2 mg/mL). At sub-MIC levels, MEW dose-dependently increased doubling times of S. mutans and S. sobrinus up to 258% and 400%, respectively. Furthermore, MEW inhibited acid production, acid tolerance, and biofilm formation of S. mutans and S. sobrinus at sub-MIC levels. The GC–MS analysis revealed the presence of mono- and disaccharides, sugar alcohols, and organic acids as main components. These data suggest that MEW might be useful for restraining physiological activities of cariogenic bacteria. [Copyright &y& Elsevier]

Vibrio parahaemolyticus was isolated from the internal organs of diseased sea bass (Dicentrarchus labrax) cultured in a marine cage farm and an inshore fish farm in the summer 2010. All strains isolated from diseased sea bass were tested for virulence by intraperitoneal injection. The isolates (n = 6) were pathogenic for sea bass. Only bacterial strains showing haemolytic activity were virulent. LD50 values ranged from 3.52 × 104 to 2.29 × 106 cfu fish−1. In this study, we report the characterization and the virulence of V. parahaemolyticus strains isolated from sea bass originating from two different fish farms (marine cage farm and inshore fish farm in Tunisia). [ABSTRACT FROM AUTHOR]

Aim: The purpose of this study was to characterize phenotypically and genotypically the serotypes of the E. coli O111 associated with diarrheal disease and assess the variation among serotypes in terms of specific virulence factors and HeLa cells adherence patterns. Background: Escherichia coli O111 serogroups are prevalent in endemic or sporadic cases of diarrhea, especially in developing areas. Patients and methods: A total of 54 strains of E. coli O111 isolated from diarrheal and healthy cases were included in this study. Flagella antigens of motile and non-motile strains were identified by fliC-RFLP method (H types) and confirmed with agglutination test using H-specific antisera. All strains were tested for the presence of 5 different gene regions associated with virulence (eaeA, eaeB, bfpA, sxt and EAF plasmid) by PCR and the patterns of bacterial attachment to HeLa cells was assayed in cell culture. Results: Of 54 E. coli O111 strains, 89% were typeable with standard H antisera and the remaining 11% of strains were non-motile (H -). Twenty-three different H type were distinguished among the O111 strains by PCR-RFLP. The most common serotypes included H21, H9, H2, H6 and H12 (48%). Serotypes O111:H9 were represented by strains with 2 patterns of virulence genes (eaeA+/bfpA+/EAE+, and eaeA+/bfpA-/EAE-) and serotype H14 was represented by strains w ith the single eaeA+/bfpA+/EAE- combination. Four distinct patterns of adherence were distinguished: LA, LLA, AA and DA. All of serotypes with the eaeA+/bfpA+/EAE+, or eaeA+/bfpA+/EAE-, combination isolated from children with diarrhea exhibited the LA pattern, and serotypes with eaeA+/bfpA-/EAF- showed the LLA, while the majority of the strains isolated from healthy cases exhibited the DA, AA and NA patterns. Conclusion: Strains of this O serogroup represented a diverse of serotypes with a variety of virulence factors and mechanisms of pathogenesis. [ABSTRACT FROM AUTHOR]

To evaluate the frequency of the aerolysin ( aerA), cytotoxic enterotoxin ( alt) and serine protease ( ahp) genes in Aeromonas hydrophila isolates from different sources, and to determine the relationship between the presence of these genes and virulence of A. hydrophila in zebrafish. Aeromonas hydrophila isolates from clinical cases ( n = 40), from healthy fish ( n = 22) and from water environment ( n = 21) were analysed with respect to the prevalence of aerA, alt and ahp genes by PCR assay. These virulence factors occur among clinical isolates as well as among isolates from healthy fish and water environment. The majority (97·6%) of the strains examined carried one or more virulence genes. The isolates were divided into seven genetic profiles on the basis of PCR result: aerA alt ahp (62·7%), aerA alt ahp (13·3%), aerA alt ahp (10·8%), aerA alt ahp (4·8%), aerA alt ahp (3·6%), aerA alt ahp (2·4%) and aerA alt ahp (2·4%). A higher frequency of genetic group aerA alt ahp was determined in the isolates from diseased animals compared to those from healthy fish or water environments. Virulence properties of 26 representative strains belonging to the seven genetic profiles were further characterized. Results demonstrated that as the present of virulence genes increased, the proteolytic, haemolytic and cytotoxic activities of extracellular products also increased. And the 50% lethal doses (LDs) of aerA alt ahp isolates (<10) in zebrafish were lower when compared with the strains expressing one or combinations of two virulence genes (>10). Virulence properties of A. hydrophila correlated well with the presence of virulence genes tested. aerA alt ahp was more frequent virulence genotype in A. hydrophila isolates from clinical diseases than from healthy fish and water environment, and the aerA alt ahp isolates were more virulent to zebrafish compared to the other six genetic profiles. The detection for aerA, alt and ahp can be used for virulence typing of A. hydrophila isolates. [ABSTRACT FROM AUTHOR]

Abstract: The distribution of virulence properties in 142 strains of Aeromonas isolated from diarrhoeic patients, food and surface water in Italy and identified by biochemical and molecular methods was investigated. The virulence properties studied were the presence of genes for the aerolysin (aerA), heat-stable cytotonic enterotoxin (ast), heat-labile cytotonic enterotoxin (alt), cytotoxic enterotoxin (act); and cytotoxicity for Vero cells and adhesion on Hep-2 cells. A. hydrophila and A. caviae were the species most commonly isolated from clinical and environmental samples (9/30; 30.0% and 5/27; 18.5%, respectively) while mesophilic A. salmonicida was most common in food samples (19/80; 23.7%). Out of 142 strains, 86 (60.6%) were positive for at least one of the virulence properties. All the toxin genes were present in 4/18 (22.3%) of clinical strains. Most of the food isolates (54/55; 98.2%) were cytotoxic and most of the environmental strains (12/13; 92.3%) were adhesive. The aerA gene was present in most toxigenic strains (72/86; 83.7%), irrespective of their origin. The growth temperature affected the expression of cytotoxicity and adhesivity. Aeromonas strains from food and surface water frequently had toxin gene patterns similar to those of clinical strains and expressed virulence properties at human body temperature. These findings indicate that aeromonads have the potential to cause human illness and confirm the role of food and water as vehicles for Aeromonas diseases. [ABSTRACT FROM AUTHOR]

Seaweeds known as “Mauro” are traditionally used fresh or to prepare omelettes in Sicily (Italy). Twenty samples sold in Catania between May 2005 and September 2007 were analyzed for Escherichia coli, Total Enterobacteria, Aeromonas spp., Pseudomonas spp., Vibrio spp., and Salmonella spp. Thirty Vibrio strains were examined for the presence of the virulence genes, toxR, toxRS, tl, tdh, and trh in the genomes of the isolates. Total Enterobacteria ranged between 2.23 and 6.85 log CFU/g, and in six samples, E. coli ranged between 0.70 and 2.74 log CFU/g. Aeromonas spp. was present in samples between 1.0 and 5.90 log CFU/g, while Pseudomonas spp. ranged between 2.70 and 7.27 log CFU/g. Vibrio spp. was present in 75% of samples at values between 1.30 and 4.60 log CFU/g. The most frequently isolated species was V. alginolyticus (76.66% of isolates), of which 82.60% were positive for toxR and the remaining 17.40% of strains were positive for toxRS. V. parahaemolyticus was identified in 13.33% of strains; all were positive for toxR and, in one case, for both toxR and toxRS. V. coralliitycus was isolated in 6.66% of strains (all positive for toxR), and one was identified as V. mimicus (positive for toxRS). The results of this study suggest that there is need for stringent quality control during harvesting and distribution of Mauro. [ABSTRACT FROM AUTHOR]

Summary: Background: The epidemiology and virulence properties of pathogenic Escherichia coli among food handlers in tourist destination hotels in Kenya are largely uncharacterized. Method: This cross-sectional study among consenting 885 food handlers working in nine luxurious tourist hotels in Nairobi, Kenya determined the epidemiology, virulence properties, antibiotics susceptibility profiles and conjugation abilities of pathogenic Escherichia coli. Result: Pathogenic Escherichia coli was detected among 39 (4.4%) subjects, including 1.8% enteroaggregative Escherichia coli (EAEC) harboring aggR genes, 1.2% enterotoxigenic Escherichia coli (ETEC) expressing both LT and STp toxins, 1.1% enteropathogenic Escherichia coli (EPEC) and 0.2% Shiga-like Escherichia coli (EHEC) both harboring eaeA and stx2 genes respectively. All the pathotypes had increased surface hydrophobicity. Using multivariate analyses, food handlers with loose stools were more likely to be infected with pathogenic Escherichia coli. Majority 53.8% of the pathotypes were resistant to tetracycline with 40.2% being multi-drug resistant. About 85.7% pathotypes trans-conjugated with Escherichia coli K12 F− NAr LA. Conclusion: The carriage of multi-drug resistant, toxin expressing pathogenic Escherichia coli by this population is of public health concern because exposure to low doses can result in infection. Screening food handlers and implementing public awareness programs is recommended as an intervention to control transmission of enteric pathogens. [Copyright &y& Elsevier]

Introduction: Streptococcus mutans has been strongly implicated as the principal etiological agent in dental caries. As a gram-positive bacterium, S. mutans has a thick and compact cell wall to maintain the cell shape and protect the cells against mechanical or osmotic damage. Previous studies have proved that peptidoglycan is the main component of the cell wall involved in the autolysis or biofilm formation processes. Methods: In this study, we investigated the gene SMU.1426c in the amino-sugar metabolism pathway of S. mutans UA159, which encodes phosphoglucosamine mutase (GlmM). The glmM gene that functions in the biosynthesis of peptidoglycan has been well investigated in Escherichia coli. Here a glmM mutant strain of S. mutans UA159 was constructed and several virulence properties were investigated. Results: The mutant devoid of the glmM gene displayed long chains, reduced growth rate and increased autolysis. Biofilm formation by the mutant was found to be attenuated. Conclusion: These results proved that peptidoglycan biosynthesis plays an important part in a series of bacterial morphologies. The glmM gene may have a constructive role in the virulence properties of S. mutans. [ABSTRACT FROM AUTHOR]

The virulence characteristics of 87 strains of halophilic Vibrio spp. from seawater collected near aquaculture areas and seafood products were evaluated by in vitro and in vivo methods.Adhesive properties were revealed in 69% of the analysed strains in Caco-2 cells and in 82.7% when using Hep-2 cells. A weak type of adherence seems to be more common. 19.3% of the strains, prevalently represented by V. alginolyticus, appears to produce cytotoxic effects on HeLa cell line while 8.6% exhibits enterotoxic activity. Five of the six V. parahaemolyticus strains results able to produce a thermostable direct haemolysin (TDH), confirmed as the major virulence factor in the pathogenic mechanism of action of this Vibrio species. Because of the strain-specific pathogenicity of most halophilic Vibrio spp., their detection in seafood, giving particular attention to their pathogenicity, is necessary to improve the control of these products. [Copyright &y& Elsevier]

Porphyromonas gingivalis (Bacteorides gingivalis) strain W50 and variants isolated from continuous culture designated W50/BPI (black pigmented), W50/BR1 (brown pigmented) and W50/BE 1 (beige or non-pigmented) were previously shown to lose virulence with the loss of pigmentation (8). Major properties which may affect the virulence and metabolism of P. gingivalis were compared amongst the 4 strains. The non-pigmented strain lost the ability to hemagglutinate sheep erythrocyte, had a reduced hydrophobicity and possessed lower levels of proteolytic activity. Defects in the electron transport system occurred at the level of cytochrome b but not menaquinone synthesis and resulted in an altered metabolic end product profile of the non-pigmented strain. [ABSTRACT FROM AUTHOR]

The α subunit ( ATP1 ) is a vital component of mitochondrial complex V which counts for the majority of cellular ATP production in a living organism. Nevertheless, how the α subunit influences other cellular processes such as pathogenicity in Candida albicans remains poorly understood. To address this question, ATP1 mutant ( atp1 Δ/Δ) and the gene-reconstituted strain ( atp1 Δ /ATP1 ) have been constructed in this study and their pathogenicity-related traits are compared to those of wild type (WT). In a murine model of disseminated candidiasis, atp1 Δ/Δ infected mice have a significantly higher survival rate and experience a lower fungal burden in tissues. In in vitro studies atp1 Δ/Δ lose a capability to damage or destroy macrophages and endothelial cells. Furthermore, atp1 Δ/Δ is not able to grow under either glucose-denial conditions or high H 2 O 2 conditions, both of which are associated with the potency of the macrophages to kill C. albicans . Defects in filamentation and biofilm formation may impair the ability of atp1 Δ/Δ to penetrate host cells and establish robust colonies in the host tissues. In concert with these pathogenic features, intracellular ATP levels of atp1 Δ/Δ can drop to 1/3 of WT level. These results indicate that the α subunit of Complex V play important roles in C. albicans pathogenicity.