The role of intestinal microbiota in the pathogenesis of colorectal carcinoma.

The symbiotic relationship between intestinal microbiota and the host is a major mechanism of prevention against the development of chronic and metabolic diseases. The intestinal microbiota provides several physiological functions of the organism from the creation of a natural functional barrier with a subsequent immunostimulatory activity up to affecting the energy metabolism of the host. Disruption of physiological intestinal microbiota is reported as one of the major etiological factors of initiation and progression of colorectal carcinoma (CRC). Chronic low-grade inflammation is associated with the development of CRC, through the production of inflammatory cytokines and reactive oxygen species. CRC occurs in association with high-protein and high-fat diets in combination with low-fiber intake. The problem of intestinal dysbiosis and oncological diseases is a multidisciplinary problem and it is necessary to focus on several fields of medicine such as public health, clinical pharmacology, and internal medicine. The aim of this review is describing the role of gut dysbiosis in pathogenesis of colorectal carcinoma.

Antibiotic susceptibility and production of endotoxin by Ochrobactrum anthropi isolated from environment and from patients with cystic fibrosis.

The aim of this work was to compare production of endotoxin and to determine susceptibility to antibiotics in two groups of specimens-wild-type strains Ochrobactrum anthropi isolated from the environment and the strains isolated from patients with cystic fibrosis. The determination of the endotoxin produced by the test strains was carried on by using a limulus amebocyte lysate test (LAL test). Determination of ATB sensitivity was accomplished by means of a broth dilution method in a microtiter plate (MIC). No significant difference was found between the group of ochrobacters isolated from the environment and the group of ochrobacters isolated from cystic fibrosis patients. Antibiotic sensitivity testing has indicated that the resistance to tigecycline, trimethoprim/sulfamethoxazole, and gentamicin was slightly higher in strains isolated from cystic fibrosis patients in comparison with strains isolated from the environment. In general, most of the test strains were sensitive to most of the antibiotics tested. Significant resistance has been demonstrated for cefotaxime. Resistance was also found for gentamicin in strains number 4 and 7. The MIC was equal to the breakpoint for this antibiotic (8000 mg/L).

Effect of hyperbaric air on endotoxin from Bacteroides fragilis strains.

The aim of the project was to determine any effect of hyperbaric air on Bacteroides fragilis strains cultivated under hyperbaric conditions. Previously, it was hypothesized that there was a correlation between the presence of Bacteroides bacteria in patients preferring a meaty diet and cancer of the small intestine, and particularly of the large intestine and rectum. With respect to the fact that Bacteroides fragilis (BAFR) group are important producers of endotoxins, measurement and statistical evaluation of endotoxin production by individual strains of isolated Bacteroides species were used to compare bacteria isolated from various clinical samples from patients with colon and rectum cancer in comparison with strains isolated from other non-cancer diagnoses. Endotoxin production was proven by quantitative detection using the limulus amebocyte lysate (LAL) test in EU/mL. Production of endotoxins in these bacteria cultured under hyperbaric air conditions was higher than those strains cultured under normobaric anaerobic conditions. But these differences in endotoxin production were not statistically significant (t test with log-transformed data, p value = 0.0910). Based on a two-tier t test for lognormal data, it is possible to cautiously conclude that a statistically significant difference was found between endotoxin production by Bacteroides fragilis strains isolated from non-carcinoma diagnoses (strains (1-6) and strains isolated from colorectal carcinoma diagnoses (strains 7-8; Wilcoxon non-parametric test p = 0.0132; t test = 0.1110; t test with log-transformed data, p value = 0.0294).

Isolation and characterization of Clostridium difficile from shellfish and marine environments.

This pilot study was carried out to evaluate the occurrence of Clostridium difficile in marine environments and in edible shellfish. Samples of seawater, sediment, and zooplankton were collected at five sampling stations in the Gulf of Naples. Six samples of edible shellfish, furthermore, were obtained: two from mussel farms and four from wholesalers. The isolation and the characterization of C. difficile strains were carried out using selective media and molecular techniques, respectively. C. difficile was isolated from nine of the 21 samples investigated. Shellfish and zooplankton showed the highest prevalence of positive samples. No C. difficile was detected in marine sediment. Majority of the C. difficile isolates were toxin A/B positive. Six known different PCR ribotypes (003, 005, 009, 010, 056, and 066) were identified, whereas one strain may represent a new PCR ribotype. C. difficile may be present in the marine environment in Southern Italy, including shellfish and zooplankton. This study is reporting the isolation of C. difficile from zooplankton, clams, and mussels and pointing out a new possible route to exposure to C. difficile of healthy individuals in the community.

Lyme borreliosis--analysis of the trends in Slovakia, 1999-2008.

Lyme borreliosis (LB) presents as one of the most frequent tick-borne diseases in Europe with more than 85,000 reported cases every year. The transport of this disease on humans is by tick species of the genus Ixodes. In our work, we aimed to perform a retrospective analysis of the incidence and seasonality of Lyme borreliosis during the period 1999-2008 in Slovakia. For our analysis, we used all the relevant data about the patients with Lyme borreliosis reported in the Epidemiological Informative System of Communicable Diseases in Slovakia during the decade of 1999-2008. During the observed period, there were 7,349 reported cases of LB in Slovakia. Whereas the incidence of early localized infection did not change during the observed period, there was a significant increase in the incidence of early disseminated infection and late persistent infection of LB. Seventy per cent of all patients was infected by tick bite. LB was more frequently reported in females than in males (56.1% vs. 43.9%; p < 0.05), and the most involved age group was the productive age (15-64 years). The incidence of disseminated infection and persistent infection was rising with increasing age. Regarding the seasonality of LB, we found the highest incidence during the summer months. Comparing the situation of LB in 1999 and 2008, significant increase in the number of reported cases was in April and June and from September to November (p < 0.05). Our epidemiological analysis confirmed that Lyme borreliosis requires increased attention due to its increasing incidence.

Molecular evidence of Plesiomonas shigelloides as a possible zoonotic agent.

The most frequently used method for establishing epidemiological relationships between Plesiomonas shigelloides strains is O:H serotyping. However, a number of strains are not serotypeable and isolates from diverse sources can display the same serovar. Moreover, since the zoonotic nature of Plesiomonas has been suggested and this hypothesis is based on the identical serovars found in animals and humans, we intend to use four DNA-based techniques: random amplified polymorphic DNA-PCR, enterobacterial repetitive intergenic consensus-PCR, repetitive extragenic palindromic-PCR, and pulsed field gel electrophoresis in order to screen 24 strains belonging to nine O:H serovars isolated from humans, animals, and the environment. In general, P. shigelloides showed a high genetic heterogeneity. Three pairs of strains, each containing a human and an animal isolate, displayed similar genotypes. This is the first report that provides molecular evidence that P. shigelloides may be zoonotic.

Recombining population structure of Plesiomonas shigelloides (Enterobacteriaceae) revealed by multilocus sequence typing.

Plesiomonas shigelloides is an emerging pathogen that is widespread in the aquatic environment and is responsible for intestinal diseases and extraintestinal infections in humans and other animals. Virtually nothing is known about its genetic diversity, population structure, and evolution, which severely limits epidemiological control. We addressed these questions by developing a multilocus sequence typing (MLST) system based on five genes (fusA, leuS, pyrG, recG, and rpoB) and analyzing 77 epidemiologically unrelated strains from several countries and several ecological sources. The phylogenetic position of P. shigelloides within family Enterobacteriaceae was precisely defined by phylogenetic analysis of the same gene portions in other family members. Within P. shigelloides, high levels of nucleotide diversity (average percentage of nucleotide differences between strains, 1.49%) and genotypic diversity (64 distinct sequence types; Simpson's index, 99.7%) were found, with no salient internal phylogenetic structure. We estimated that homologous recombination in housekeeping genes affects P. shigelloides alleles and nucleotides 7 and 77 times more frequently than mutation, respectively. These ratios are similar to those observed in the naturally transformable species Streptococcus pneumoniae with a high rate of recombination. In contrast, recombination within Salmonella enterica, Escherichia coli, and Yersinia enterocolitica was much less frequent. P. shigelloides thus stands out among members of the Enterobacteriaceae. Its high rate of recombination results in a lack of association between genomic background and O and H antigenic factors, as observed for the 51 serotypes found in our sample. Given its robustness and discriminatory power, we recommend MLST as a reference method for population biology studies and epidemiological tracking of P. shigelloides strains.

Serotypes and anti-microbial susceptibility of Plesiomonas shigelloides isolates from humans, animals and aquatic environments in different countries.

A total of 73 strains of Plesiomonas shigelloides isolated from humans (24 strains) animals (21 strains) and aquatic environment (28 strains) were determined for their O:H serotype and susceptibility to 18 anti-microbial substances and to the vibriostatic agent O/129. Of all strains, 86.3% were typeable by the O and 94.5% by the H anti-sera used. The serotype distribution was heterogeneous within a country and between the countries. Of the 57 different serotypes identified, O11:H2 (2 strains), O22:H3 (4 strains), O35:HH11 (2 strains), O52:H3 (2 strains) and O90:H6 (2 strains) were found among isolates from humans and animals (mainly in cats) in Finland and Cuba, and O23:H1a1b (3 strains) among isolates from environmental sources in Slovak Republic and Italy. Most (93-100%) of all strains were susceptible to all anti-microbials tested but resistant (92-96%) to the broad-spectrum penicillins (ampicillin, mezlocillin). No correlation between anti-microbial resistance patterns and serotypes was found.