Heriberto Fernández

Isolation of thermotolerant species of Campylobacter from commercial chicken livers

The qualitative and quantitative contamination levels of Campylobacter spp. in frozen commercial chicken livers were assessed. From the 126 samples studied, 117 (92.9%) were positive for Campylobacter spp. C. coli was isolated more frequently (78.6%) than C. jejuni (21.4%). The MPN method showed that Campylobacter contamination levels ranged from 10 to > 230 bacteria/100 ml of liquid exuded by livers.

Prevalence of thermotolerant species of Campylobacter and their biotypes in children and domestic birds and dogs in Southern Chile

The prevalence of thermotolerant Campylobacter in diarrhoeic and healthy children as well as in dogs, hens, ducks and pigeons was determined in Southern Chile. Campylobacter were found in 34.5% of the faecal samples examined. The isolation rate of Campylobacter in diarrhoeic and healthy children was 16.3% and 6.4% respectively. Despite C. jejuni was always more frequent than C. coli, the latter was isolated with a high frequency (29%) from patients with diarrhoea. C. jejuni and C. coli biotypes I and II were found in healthy and diarrhoeic children and were predominant in all the animals species studied. This may point out towards the possible origin of strains infecting children.

Assessment of the prevalence and diversity of emergent campylobacteria in human stool samples using a combination of traditional and molecular methods

This study aims to assess the diversity of campylobacteria (Campylobacter and Arcobacter) in human fecal samples from patients with diarrhea (n = 140) and asymptomatic controls (n = 116) in Chile, using a combination of traditional culture and molecular methods. The culture methods detected campylobacteria in 10.7% of the patients with diarrhea and in 1.7% of the controls. In contrast, the molecular methods detected campylobacteria more often than the traditional culture, with a prevalence of 25.7% and 5.2%, respectively. The traditional methods only recovered the species Campylobacter jejuni, Campylobacter coli, and Arcobacter butzleri, whereas the molecular methods additionally detected the emergent species Campylobacter concisus and Campylobacter ureolyticus.

OCCURRENCE OF CAMPYLOBACTER SPECIES IN HEALTHY WELL-NOURISHED AND MALNOURISHED CHILDREN

The occurrence of Campylobacter species in healthy, well-nourished and healthy, malnourished children of low socioeconomic level in Southern Chile was determined. Campylobacter carriers were significantly most frequent among malnourished (31.4%) than among well-nourished (9.9%) children. Six species were isolated from malnourished children whereas four were found among well-nourished children. C. upsaliensis was the most frequent (13.3%) species isolated from malnourished children, followed by C. lari (7.6%) and C. fetus ssp. fetus (1.9%).

Arcobacter butzleri an emerging enteropathogen: communication of two cases with chronic diarrhea

Os primeiros dois casos de diarreia cronica por Arcobacter butzleri no sul do Chile sao apresentados. As caracteristicas clinicas, a ausencia de outros enteropatogenos, virus ou parasitas, o resultado do tratamento, bem como a associacao epidemiologica entre ambos pacientes e o fato de A. butzleri ter sido a unica bacteria isolada permitem assumir que este microrganismo seria o agente etiologico destes dois casos de diarreia cronica.

Campylobacter y campylobacteriosis: una mirada desde América del Sur

The thermotolerant species of Campylobacter have become very important in public health, especially as agents of infectious diarrhea in human beings. In this brief revision we present part of the available information generated in South America about epidemiological, clinical and bacteriological aspects of campylobacteriosis and we identify some differences between the observed and documented campylobacteriosis in South America compared to those described in industrialized countries.

Especies de Arcobacter y Campylobacter en aves y mamíferos del sur de Chile

SUMMARY The isolation frequency of Arcobacter and Campylobacter species in birds and mammals of Southern Chile was determined. Five species of the Campylobacter genus [C. jejuni subsp. jejuni (25.3%), C. jejuni subsp. doylei (1.4%), C. coli (18%), C. lari (4.6%) y C. upsaliensis (3.2%)] and one of the Arcobacter genus [A. butzleri (17.3%)] were isolated. Dogs are reported as the new reservoir for C. jejuni subsp. Doylei; hens, pelicans and sparrows for C. upsaliensis; sparrows for C. lari and dogs, pelicans and sparrows for A. butzleri.

Analysis of Helicobacter pylori isolates from Chile: occurrence of selective type 1 Lewis b antigen expression in lipopolysaccharide

Previous studies have shown that the LPS of Helicobacter pylori isolated from North American and European hosts predominantly expresses type 2 Lewis x (Le(x)) and Le(y) epitopes, whilst the LPS from Asian strains has the capacity to express type 1 Le(a) and Le(b) structures. The aim of this study was to evaluate the expression of Le antigens and the cytotoxin-associated antigen (CagA) by H. pylori isolates from Chile. A total of 38 isolates were screened. The expression of Le antigens and CagA was determined by whole-cell indirect ELISA, using commercially available monoclonal anti-Le and polyclonal anti-CagA antibodies. LPS profiles of H. pylori isolates were assessed by gel electrophoresis and Western blotting. Expression of Le(x) and/or Le(y) epitopes was confirmed in 32/38 isolates (84 %), whilst 9/38 isolates (24 %) expressed type 1 Le(b) blood group determinants, in addition to type 2 Le(x) and Le(y) structures. Six strains (16 %) were non-typeable. The majority of H. pylori strains examined were CagA-positive (83.3 %).

Mechanisms associated with phagocytosis of Arcobacter butzleri by Acanthamoeba castellanii

Acanthamoeba castellanii is a free-living amoeba widely found in environmental matrices such as soil and water. Arcobacter butzleri is an emerging potential zoonotic pathogen that can be isolated from environmental water sources, where they can establish endosymbiotic relationships with amoebas. The aim of this study was to describe the implication of mannose-binding proteins and membrane-associated receptors of glucose and galactose present in the amoebic membrane, during the attachment of Arcobacter butzleri by blocking with different saccharides. Another objective was to describe the signaling pathways involved in phagocytosis of these bacteria using specific inhibitors and analyze the implication of phagolysosome formation on the survival of Arcobacter butzleri inside the amoeba. We infer that the attachment of Arcobacter butzleri to the amoeba is a process which involves the participation of mannose-binding proteins and membrane-associated receptors of glucose and galactose present in the amoeba. We also demonstrated an active role of protozoan actin polymerization in the phagocytosis of Arcobacter butzleri and a critical involvement of PI3K and RhoA pathways. Further, we demonstrated that the tyrosine kinase-induced actin polymerization signal is essential in Acanthamoeba-mediated bacterial uptake. Through phagolysosomal formation analysis, we conclude that the survival of Arcobacter butzleri inside the amoeba could be related with the ability to remain inside vacuoles not fused with lysosomes, or with the ability to retard the fusion between these structures. All these results help the understanding of the bacterial uptake mechanisms used by Acanthamoeba castellanii and contribute to evidence of the survival mechanisms of Arcobacter butzleri.

Isolation of thermotolerant Campylobacter species from two populations of chickens bred in confinement and at liberty

Estudou-se a frequencia de isolamento de Campylobacter spp. em frangos domesticos e frangos mantidos em confinamento permanente, na cidade de lquitos (Peru). Campylobacter spp. foi isolado em 54,0% no primeiro grupo e 35,0% no segundo (p<0,005). Das especies termotolerantes classicas, as mais frequentes foram C. jejuni e C. coli. A presenca de C. lari nessas aves, assinala a importância delas como reservatorio natural desse microrganismo.Estudou-se a frequencia de isolamento de Campylobacter spp. em frangos domesticos e frangos mantidos em confinamento permanente, na cidade de lquitos (Peru). Campylobacter spp. foi isolado em 54,0% no primeiro grupo e 35,0% no segundo (p<0,005). Das especies termotolerantes classicas, as mais frequentes foram C. jejuni e C. coli. A presenca de C. lari nessas aves, assinala a importância delas como reservatorio natural desse microrganismo.