Miriam Troncoso

Antimicrobial activity of copper surfaces against suspensions of Salmonella enterica and Campylobacter jejuni

BackgroundSalmonella enterica and Campylobacter jejuni are amongst the more prevalent bacterial pathogens that cause foodborne diseases. These microorganisms are common contaminants of poultry and poultry products. This study was aimed to evaluate the antibacterial activity of metallic copper surfaces on these important enteropathogens, and to determine the potential acquisition of copper by food exposed to this metal.ResultsThe antibacterial activity of copper surfaces was evaluated overlying them with suspensions of 106 CFU/ml of S. enterica and C. jejuni. Bacterial counts obtained after 0, 2, 4 and 8 hours at 10°C and 25°C were compared with those obtained in stainless steel and a synthetic polymer as control surfaces. The results showed that when these enteropathogens were kept in contact with copper a significant antibacterial activity was noted, on the contrary when the same load of pathogen suspensions were tested over the control surfaces it was found that the bacterial counts remained unchanged or even increased with time. The potential acquisition of copper by food exposed to this surface was also evaluated. Meat exposed for one hour to a copper surface adsorbed residual copper in a time dependant manner.ConclusionsThese results shows that metallic copper surfaces have an antibacterial activity against S. enterica and C. jejuni and suggest its potential application as an inhibitory agent in the various stages of the food processing operations.

In Vitro and in Vivo Effects of Apple Peel Polyphenols against Helicobacter pylori

The inhibitory effects of a standarized apple peel polyphenol-rich extract (APPE) against Helicobacter pylori infection and vacuolating bacterial toxin (VacA) induced vacuolation were investigated. Apple peel polyphenols significantly prevented vacuolation in HeLa cells with an IC(50) value of 390 microg of gallic acid equivalents (GAE)/mL. APPE also displayed an in vitro antiadhesive effect against H. pylori. A significant inhibition was observed with a 20-60% reduction of H. pylori attachment at concentrations between 0.250 and 5 mg of GAE/mL. In a short-term infection model (C57BL6/J mice), two levels of APPE doses (150 and 300 mg/kg/day) showed an inhibitory effect on H. pylori attachment. Orally administered apple peel polyphenols also showed an anti-inflammatory effect on H. pylori-associated gastritis, lowering malondialdehyde levels and gastritis scores.

Occurrence and enumeration of Campylobacter spp. during the processing of Chilean broilers

BackgroundThermotolerant Campylobacter is among the more prevalent bacterial pathogens that cause foodborne diseases. This study aimed at evaluating the occurrence of thermotolerant Campylobacter contamination in chicken carcasses and processing plant stations (chilling water, scalding water, defeathering machinery, evisceration machine, and transport crates) in two of the Chilean main slaughterhouses. In addition, the isolation rates of thermotolerant Campylobacter during evisceration and following chiller processing were compared.ResultsThe overall slaughterhouse contamination with thermotolerant Campylobacter was 54%. Differences were evident when the results from each plant were compared (plant A and plant B was 72% and 36%, respectively). The sampling points with the greatest contamination rates in both plants were after evisceration (90% and 54%, for plants A and B respectively). The decrease of thermotolerant Campylobacter contamination after chilling was significant (2 and 1.6 logs for plant A and B respectively P < 0.05).ConclusionOur findings indicate that chilling process has a limited effect in the final products Campylobacter contamination because poultry enter the slaughter processing with high counts of contamination. This may represent a health risk to consumers, if proper cooking practices are not employed. The levels and frequencies of Campylobacter found during the processing of Chilean poultry appear to be similar to those reported elsewhere in the world.

Association between polymerization degree of apple peel polyphenols and inhibition of Helicobacter pylori urease.

Apple peel extracts and their fractions pooled according to their molecular size were prepared and evaluated for their inhibitory activity against Helicobacter pylori and Jack bean ureases. Urease Inhibitory effect of apple peel polyphenols (APPE) extracted from the Granny Smith variety was concentration-dependent and reversible. High molecular weight polyphenols (HMW) were more active against Helicobacter pylori and Jack bean ureases than low molecular weight polyphenols with IC50 values of 119 and 800 microg GAE/mL, respectively. The results suggest that monomeric compounds (mainly flavan-3-ols-and quercetin-O-glycosides) will not be implicated in the antiurease effect displayed by the apple peel polyphenolic extract. Thus, as a byproduct, apple peel is suitable for developing functional ingredients that could be useful for neutralizing an important Helicobacter pylori colonization factor.

In vitro inhibitory effect of apple peel extract on the growth of Helicobacter pylori and respiratory burst induced on human neutrophils.

In the present work, the in vitro effect of a standardized extract of apple peel APPE (60% of total polyphenols; 58% of flavonoids; 30% of flavan-3-ols and procyanidins) was evaluated with regard to the viability of Helicobacter pylori. The cytotoxic effect of APPE on H. pylori was also evaluated through the resazurin assay and ATP level determination. In both assays, APPE showed an early cytotoxic effect, which was both concentration and time-dependent. Additionally, the effect of APPE on the intra and extracellular production of reactive oxygen species (ROS) was evaluated in human neutrophils stimulated by H. pylori, phorbol myristate acetate (PMA), and formyl-methionyl-leucyl-phenylalanine (fMLP). The extracellular and intracellular production of ROS was evaluated through chemiluminiscence with the isoluminol-horseradish peroxidase (HRP) and luminol-superoxide dismutase (SOD)-catalase systems, respectively. APPE showed an inhibiting effect on the multiplication of two H. pylori strains (ATCC 43504 and TX136) with a miminnum inhibitory concentration (MIC) value of 112.5 microg gallic acid equivalent (GAE)/mL. APPE inhibited the respiratory burst of neutrophils induced by H. pylori, PMA, and fMLP in concentration-dependent form. Interestingly, this effect was observed on both the interior and exterior of the neutrophil. This result suggests that apple peel polyphenols have an attenuating effect on the damage to gastric mucosa caused by neutrophil generated ROS and, particularly, when H. pylori displays its evasion mechanisms.

Helicobacter pylori infection in Chile

This article summarizes studies designed to evaluate the role of Helicobacter pylori infection in Chile, described in 21 reports from nine centers in various Chilean regions published between 1985 and 1995. According to their data, H. pylori infection is quite frequent among patients with a variety of gastric conditions, including adults (43%-92%) and children (6%-100%). Levels of specific IgG antibodies to H. pylori are also elevated among patients with duodenal ulcers (100%) and gastritis (86%) as well as asymptomatic adults (75%). Combination therapy with three (but not two) drugs has been proved effective, with clinical improvement, ulcer cure, and H. pylori eradication occurring in well-controlled studies. Available evidence suggests that antibiotic resistance is not a major problem in treatment. The H. pylori reinfection rate is low (4.2% per year), suggesting that combination therapy with three drugs constitutes a cost-effective alternative for treating colonized symptomatic patients. Concurrent preliminary studies revealed that antibodies to VacA but not CagA proteins correlate with disease severity in Chilean patients. It can be concluded that local research assists local administrators of health resources to implement adequate policies to prevent, control, and treat H. pylori-related pathologies.

cagA and vacA in strains of Helicobacter pylori from ulcer and non-ulcerative dyspepsia patients

BackgroundThe cytotoxin associated gene A (cagA), and the vacuolating cytotoxin gene A (vacA) of Helicobacter pylori have been associated to phenotypic characteristics of virulence. The objectives of this study were to detect the presence of cagA and to characterize the allelic variants of vacA in 63 strains of H. pylori isolated from colonized individuals with different clinical outcomes.Methods38 strains were isolated from patients with non-ulcerative dyspepsia (NUD) and 25 were isolated from colonized individuals with peptic ulcers. The genotypic characterization was carried out utilizing PCR methodology. The presence of the cagA gene was detected using two set of primers from the middle conservative region of the cagA, and primers for the signal and middle region were used for the genotyping of vacAResultsThe presence of cagA showed similar rates in strains from peptic ulcers (60%) and NUD patients (55%). Also similar was the prevalence of the allelic form s1 of vacA between the strains obtained from ulcers or NUD patients. However, the combination cagA+/vacA s1m1 was found more frequently among the H. pylori strains from peptic ulcer patients (52%) than among strains isolated from NUD patients (26%), this difference was statistically significant (p = 0.035).ConclusionsThe presence of either cagA or the allelic variant s1 vacA alone do not have a predictive value as as a risk markers of severe gastric pathologies in the Chilean population. However, being infected by a H. pylori strain with the genotype cagA+/vacA s1m1 may be associated to an increased risk of acquiring a peptic ulcer disease.

Enteropathogen carriage by healthy individuals living in an area with poor sanitation

Faecal carriage of bacterial enteropathogens (enteropathogenic Escherichia coli (EPEC), shigellae and salmonellae) was studied in 265 individuals: 65 infants 3-6 months of age (50 bottle-fed and 15 breast-fed), 100 school-age children 8-10 years of age and 100 adults 21-50 years of age. All were apparently healthy, did not have gastrointestinal symptoms, had not received antibiotics in the preceding fortnight and were not malnourished. Enteropathogens were isolated from the faeces of 24 individuals (9.1%). Cultures were positive for enteropathogens in 20% of the infants (both breast- and bottle-fed), 8% of school-age children and 3% of the adults. EPEC was the most frequent isolate. Twelve different serotypes were detected. The highest recoveries were E. coli 026:K60 and 044 . K74. Shigella was detected only in school-age children (2%) and salmonella only in adults (1%). Campylobacter jejuni and Yersinia enterocolitica were studied only in the school-age children: there was one isolate of each of them. Most enteropathogens isolated were susceptible to the majority of the antibiotics tested. Only four E. coli strains, isolated from bottle-fed infants, could be considered multi-resistant. Two of the strains wer E. coli 044:K74 and 020a020c:K61. The remainder were E. coli 0111:K58 and wee capable of transferring some of their antibiotic resistance traits to a recipient strain.

Biotypes, serogroups and antibiotic susceptibility of Campylobacter jejuni and Campylobacter coli in Chile.

Phenotypic markers were studied in 105 strains of thermophilic campylobacters isolated from human beings, animals and drinking water in Santiago, Chile. The strains were identified as Campylobacter jejuni (n = 49) and Campylobacter coli (n = 56). Biotypes I and II (Lior schema) accounted for 96% C. jejuni isolates, the other 4% being biotype IV but the two biotypes of C. coli were about equally represented. A total of 28 serogroups (Liors heat-labile antigens) were identified. Lior 13, 9, 79, 2 and 4 were prevalent among the C. jejuni, while Lior 8, 21 and 29/75 were prevalent among the C. coli isolates. These serogroups accounted for 73% all isolates. The distribution of biotypes and serogroups in patients and asymptomatic persons were similar. Human campylobacters were often resistant to ampicillin (31%) but sensitive to erythromycin and furazolidone. Swine C. coli isolates proved resistant to streptomycin (46%), tetracycline (38%) and erythromycin (15%). Determination of phenotypic and serological characters provides valuable epidemiological markers in the study of campylobacter infections.

Immunoglobulin G antibody response to infection with coccoid forms of Helicobacter pylori.

ABSTRACT An increasing number of studies support a potential role for coccoid forms in Helicobacter pylori infection. Evidence for this was obtained through scanning microscopy, genetic analysis for virulence traits, examination of the presence and activity of key enzymes, and other methods. We studied the serum immunoglobulin G responses to coccoid H. pylori forms by enzyme-linked immunosorbent assay (ELISA) and immunoblotting and compared them with those of bacillary cells. Sera from a total of 295 infected individuals were studied; these included sera from 100 patients with duodenal ulcers, 98 patients with nonulcer dyspepsia, 11 patients with gastroduodenal cancer, and 86 asymptomatic individuals. Initially, we characterized and selected coccoid and bacillary antigenic preparations by one-dimensional (1-D) and 2-D gel electrophoresis and immunoblotting. Data showed that coccoid and bacillary preparations with comparable protein contents have similar patterns in 1-D and 2-D electrophoresis gels and antigenic recognition at blotting. These results revealed that coccoid and spiral antigens in ELISA can equally recognize specific antibodies to H. pylori in sera from infected individuals. The analysis of the spiral and coccoid preparations by Western blotting showed no major differences in antigen recognition. No specific bands or profiles associated with a single gastric condition were identified.