Specific detection of Arcobacter spp. in estuarine waters of Southern Italy by PCR and fluorescent in situ hybridization

AIM

To evaluate the reliability of culture-independent methods in comparison with culture-dependent ones for the detection of Arcobacter spp. in estuarine waters of Southern Italy.

METHODS AND RESULTS

PCR and fluorescent in situ hybridization (FISH) procedures were used to detect arcobacters directly in water samples and after enrichment cultures. The samples totally were positive by molecular methods (PCR and FISH) but only 75% were culture positive, confirming the limitation of these latter to detect Arcobacter spp. in natural samples. Culturable arcobacters were retrieved in all times except in July, and isolated species were ascribed only to Arcobacter cryaerophilus.

CONCLUSIONS

Culturable and nonculturable forms of Arcobacter in the estuarine environment were present. PCR assays were more sensitive than traditional culture in detecting Arcobacter butzleri and A. cryaerophilus. FISH comparatively to PCR technique may provide information about cell morphology and viability of single cells.

SIGNIFICANCE AND IMPACT OF THE STUDY

Our investigation indicates the existence of an environmental reservoir of potential pathogenic arcobacters in an estuarine Italian area, which may survive under a viable but not culturable state.

Molecular detection of Bartonella henselae and Bartonella clarridgeiae in clinical samples of pet cats from Southern Italy

Bartonella henselae is considered an emerging pathogen of veterinary and medical interest that can be occasionally transmitted to humans. Cats are considered to be the only reservoir host for B. henselae. In this study, we used a nested-PCR assay to investigate the prevalence of B.henselae and Bartonella clarridgeiae DNA in peripheral blood samples, fine needle lymph node aspirate specimens and oral swabs from 85 cats in order to develop an easy diagnostic strategy for the selection of infection-free cats that are being considered as pets, especially for immunocompromised patients. Overall, molecular analysis showed that 71 cats (83.5%) tested PCR positive for the presence of B. henselae DNA. PCR amplification of DNA B. henselae produced positive products from lymph node aspirate specimens (62/85; 72.9%) similar to those obtained from blood samples (60/85; 70.6%) and higher than those from oral swabs (51/85; 60%) of cats. No PCR product was obtained for B. clarridgeiae. The simultaneous analysis of three different clinical samples in our study increased the diagnostic possibilities for B. henselae infection in the examined cats from 60-72.9% to 83.5%. Lymph node aspirates were found to be the most effective clinical samples for the detection of B. henselae and blood samples were the next best. Oral swab samples were used in this study with good results when considered in combination with blood and/or lymph node aspiration. The use of nested-PCR assay on these three clinical samples may enhance the diagnostic sensitivity for bartonellosis in cats irrespective of the clinical status of animals.

Occurrence of Helicobacter pylori DNA in the coastal environment of southern Italy (Straits of Messina)

AIMS

The occurrence of Helicobacter pylori in the coastal zone of the Straits of Messina (Italy) as free-living and associated with plankton was studied.

METHODS AND RESULTS

Monthly sampling of seawater and plankton was carried out from April 2002 to March, 2003. All environmental samples analysed by cultural method, did not show the presence of H. pylori. The DNA extracted from all environmental samples was tested by PCR by using primers for H. pylori 16S rRNA, ureA and cagA. 16S rRNA PCR yielded amplified products of 522-bp in 15 of 36 (41.7%) of the environmental samples. By using the ureA primers to amplify the urea signal sequences, the predicted PCR products of 491-bp were obtained from eight (22.2%) of 36 environmental samples. PCR with cagA primers yielded amplified products of 349-bp in DNA extracted of seven of 36 (19.4%) of the environmental samples. When 16S rRNA, ureA and cagA amplified gene sequences were aligned with H. pylori 26695 and J99 genome sequences, we obtained a percentage of alignment over 90%.

CONCLUSIONS

The detection of H. pylori genes in marine samples allows us to consider the marine environment a possible reservoir for this pathogenic bacterium.

SIGNIFICANCE AND IMPACT OF THE STUDY

The direct detection of H. pylori genes may be relevant in order to consider the marine environment as significant reservoir for this bacterium.

Distribution of potentially pathogenic bacteria as free living and plankton associated in a marine coastal zone

AIMS

To determine the abundance of faecal and nonfaecal bacteria related to human and animal health, as free living or associated with small (>64 microm) and large (>200 microm) plankton, samples were collected monthly from the coastal zone at Messina (Italy).

METHODS AND RESULTS

Different enrichment and selective cultural methods were used to determine the abundance of bacteria in sea water and plankton. The bacteria were more frequently isolated from water and large plankton than from small plankton. Vibrio and Aeromonas spp. showed different distribution patterns in water and plankton. Faecal indicators were always present in water and the large size class plankton samples. Enterococci associated with large plankton were more abundant than E. coli in the winter. Vibrio species distributions were different in water and plankton samples. Among arcobacters only A. butzleri was isolated from water and plankton samples. Campylobacter spp. was always absent in small plankton and more frequent in large plankton than in water.

CONCLUSIONS

The colonization of zooplankton by potentially pathogenic bacteria is a widespread phenomenon.

SIGNIFICANCE AND IMPACT OF THE STUDY

The presence of potentially pathogenic bacteria in sea water and associated with plankton can have ecological and epidemiological implications.

Detection of Arcobacter spp. in the coastal environment of the Mediterranean Sea

The occurrence of Arcobacter spp. was studied in seawater and plankton samples collected from the Straits of Messina, Italy, during an annual period of observation by using cultural and molecular techniques. A PCR assay with three pairs of primers targeting the 16S and 23S rRNA genes was used for detection and identification of Arcobacter butzleri, Arcobacter cryaerophilus, and Arcobacter skirrowii in cultures and environmental samples. Only one of the Arcobacter species, A. butzleri, was isolated from seawater and plankton samples. With some samples the A. butzleri PCR assay gave amplified products when cultures were negative. A. cryaerophilus and A. skirrowii were never detected by culture on selective agar plates; they were detected only by PCR performed directly with environmental samples. Collectively, our data suggest that culturable and nonculturable forms of Arcobacter are present in marine environments. The assay was useful for detecting Arcobacter spp. both as free forms and intimately associated with plankton. This is the first report showing both direct isolation of A. butzleri and the presence of nonculturable Arcobacter spp. in the coastal environment of the Mediterranean Sea.

In vitro susceptibility of Arcobacter butzleri and Arcobacter cryaerophilus to different antimicrobial agents

Seventeen strains of Arcobacter butzleri and thirteen of Arcobacter cryaerophilus, were tested for their antimicrobial susceptibility to 26 antimicrobial agents. Among beta-lactams agents in this study, imipenem was the most active agent against both A. butzleri and A. cryaerophilus isolates with MIC(90) values of 2 and 4 mg/l, respectively. The most active cephalosporin tested was cefepime, although it was more active against A. butzleri (MIC(90) 8 mg/l) than A. cryaerophilus (MIC(90) 64 mg/l). Levofloxacin, marbofloxacin, enrofloxacin and ciprofloxacin were the best-performing fluoroquinolones against these species. Of the aminoglycosides, amikacin was the most active agent against both A. butzleri and A. cryaerophilus strains with MIC(90) values of 64 and 16 mg/l, respectively. All isolates showed high levels of resistance to penicillins, macrolides, chloramphenicol, trimethoprim and vancomycin.

Correlation between Helicobacter pylori infection and IL-18 mRNA expression in human gastric biopsy specimens

Our data indicate that H. pylori infection is associated with active interleukin-18 production in patients with chronic gastritis. Different cell types appear to be involved in this activity and may play a role in the development of immunopathologic damage.

p53 and anti-p53 antibodies as possible markers of a switch towards a neoplastic phenotype in patients infected by Helicobacter pylori

Helicobacter pylori is a definite carcinogen whose mechanism of action is still unknown. The aim of this work was (1) to determine the presence of p53 protein and related antibodies in patients affected by various gastric pathologies and chronically infected with H. pylori, and (2) to try to discover a test to be used as a marker of a possible switch towards a neoplastic phenotype.

Cytokine induction in murine bladder tissue by type 1 fimbriated Escherichia coli

The local cytokine response to uropathogenic phenotype Escherichia coli KBC211 infection exhibits characteristics of both TH1 and TH2 profiles. Interleukin (IL)-6, MIP-2, IL-12, IL-18, and tumor necrosis factor-alpha (TNF-alpha) are expressed, but IL-4, IL-5, and IL-10 are also present at low levels. This is clearly a complex response that should be explored more fully. The relative contributions of the bladder epithelium and other cells of the bladder wall should also be determined. Epithelial cytokine responses may be considerable, and because these cells are the first to encounter the pathogen, they will be of great importance in the immune response to pathogenic E. coli.

Activity and postantibiotic effect of marbofloxacin, enrofloxacin, difloxacin and ciprofloxacin against feline Bordetella bronchiseptica isolates

The minimum inhibitory concentration (MIC) and postantibiotic effect (PAE) of marbofloxacin, enrofloxacin, difloxacin and ciprofloxacin were evaluated in vitro against 43 feline-source Bordetella bronchiseptica strains. All strains tested were susceptible to marbofloxacin and enrofloxacin (MIC90 0.5mg/l), while 93 and 84% of the strains were susceptible, respectively, to ciprofloxacin and difloxacin with MIC(90) values of, respectively, 1 and 8mg/l. The PAE was studied in 10 strains by exposure of bacteria to marbofloxacin, enrofloxacin, difloxacin and ciprofloxacin at 5 and 10 times minimum inhibitory concentration (MIC) for 1 and 2h. Regrowth was determined by measuring the viable counts after drug removal by a 10(3) dilution procedure. PAEs increased as a function of concentration and exposure time. The mean duration of PAEs varied between 1.1 and 8.2h, showing the following order: marbofloxacin>enrofloxacin>ciprofloxacin>difloxacin. These data are encouraging since fluoroquinolones have a possible role in the clinical treatment of B. bronchiseptica infections, and the strong PAE caused by quinolones may contribute to the in vivo efficacy of these drugs.

Antimicrobial activity and postantibiotic effect of flurithromycin against Helicobacter pylori strains

The minimal inhibitory concentrations (MIC) of flurithromycin on 49 clinical isolates of Helicobacter pylori was investigated. The MICs were determined using an agar dilution technique. Flurithromycin inhibited the growth of H. pylori strains with MIC(50) and MIC(90) values of 0.156 and 0.625 mg/l, respectively. The postantibiotic effects (PAE) were studied on ten strains, by exposure of the bacteria to flurithromycin at five and ten times MIC for 1 or 2 h. Regrowth was determined by measuring the viable counts after drug removal by a 10(3) dilution procedure. All PAEs increased as a function of concentration and time of exposure. The mean duration of PAEs varied between 1.5 and 6 h. These data are encouraging since macrolides play a key role in the clinical treatment of H. pylori infections, and the strong PAE caused by flurithromycin may contribute to the in vivo efficacy of this drug.

Isolation of Arcobacter spp. from a brackish environment

Arcobacter spp. were isolated from water and mussels of two brackish lakes near Messina (Italy). The isolates were phenotypically characterized on the basis of a large battery of cultural and biochemical tests. By comparison with the reference strains Arcobacter butzleri ATCC 49616 and A. cryaerophilus ATCC 43157 they may be considered Arcobacter butzleri-like bacteria. The current isolation suggests that the brackish environment may play an important role in the survival and transmission of Arcobacter spp. also by seafood cultured in the examined waters.

Synergic activities of streptococcal pyrogenic exotoxin A and lipoteichoic acid in cytokine induction

The present study was carried out to gain insight into the mechanisms involved in the pathogenesis of streptococcal toxic shock syndrome (TSS) and other acute invasive diseases caused by Streptococcus pyogenes (GAS). Specifically, since both whole bacteria and their soluble products are often present in the blood in these conditions, we sought to detect possible synergic activities of somatic and extracellular products in inducing mediators release. For this purpose, whole blood cultures from healthy donors were incubated with different concentrations of streptococcal pyrogenic exotoxin A (SpeA), which is considered a major molecular effector of TSS, heat-killed GAS and cell-wall components such as lipoteichoic acid (LTA) and soluble peptidoglican (sPGN). Significant levels of TNF-alpha, IL-1 alpha and IFN-gamma were found in supernatants from cultures incubated with each of the four inducers alone. Whole GAS and both cell-wall components were more effective (p < 0.05) than SpeA in inducing cytokine release. Whole GAS, at weight basis, was a more potent inducer than LTA and sPGN and LTA, at weight basis, was a more potent inducer than sPGN. In order to verify possible additive or synergic effects of exotoxic and parietal compounds in inducing cytokine release, whole blood cells were incubated with mixtures of SpeA and LTA at different molecular ratio. TNF-alpha, IL-1 alpha and IFN-gamma levels in supernatants were significantly (p < 0.05) higher in supernatants of cultures stimulated simultaneously with the two components than those of cultures stimulated with a single agent. Moreover, these levels were significantly higher than the sum of cytokine levels induced by single components. This study shows that parietal compounds can act in synergy with exotoxins in inducing the release of cytokines, which appear to be the major mediators of TSS.

Activity of nine fluoroquinolones against strains of Bordetella bronchiseptica

Thirty-two strains of Bordetella bronchiseptica were tested for their antimicrobial susceptibilities to nine fluoroquinolones. The most active agents were fleroxacin, temafloxacin, ciprofloxacin (MIC90 1 microg/ml), ofloxacin, lomefloxacin and enoxacin (MIC90 2 microg/ml). Pefloxacin and norfloxacin were active only against 59.3 and 83.1%, respectively, of the strains tested, whereas rufloxacin lacked activity against all the strains of B. bronchiseptica tested.

Bactericidal activity of lansoprazole and three macrolides against Helicobacter pylori strains tested by the time-kill kinetic method

The bactericidal activities of macrolides (clarithromycin, roxithromycin and azithromicyn) and lansoprazole, alone and in combination, against Helicobacter pylori strains were evaluated. It was found that the association of lansoprazole and clarithromycin resulted in a marked synergism, while the combination of roxithromycin or azithromycin with lansoprazole had synergistic and additive effects.

In vitro activities of new quinolones against Helicobacter pylori

Compounds belonging to a new class of quinolones in which the fundamental C-6 fluorine atom was replaced were evaluated for in vitro antibacterial activity against 32 Helicobacter pylori strains. Since these substitutions resulted in higher inhibitory activities, these new desfluoroquinolones may be useful in eradicating H. pylori infections.

Porins of Pseudomonas aeruginosa induce release of tumor necrosis factor alpha and interleukin-6 by human leukocytes

The aim of this study was to examine the ability of Pseudomonas aeruginosa components to induce release of cytokines from human leukocytes. Human whole-blood cultures were incubated with several concentrations of purified P. aeruginosa products, including porins, exomucopolysaccharide, lipopolysaccharide, and toxin A. Supernatants were assayed for tumor necrosis factor alpha (TNF-alpha) and interleukin-6 (IL-6) activities. All of the P. aeruginosa components except toxin A were able to stimulate the release of both cytokines. On a weight basis, porins were as effective as lipopolysaccharide and significantly more effective than exomucopolysaccharide in inducing IL-6 release (P < 0.05). Moreover, porins were more potent than either exomucopolysaccharide or lipopolysaccharide in inducing TNF-alpha release (P < 0.05). Further experiments using isolated leukocytes suggested that monocytes were the cell population predominantly responsible for the production of both cytokines. These data indicate that P. aeruginosa porins are able to induce significant cytokine production. These components may be responsible for the chronically overactive inflammatory response associated with persistent lung infection in cystic fibrosis patients.

Interleukin-10 protects neonatal mice from lethal group B streptococcal infection

We investigated the role of interleukin-10 (IL-10) in a neonatal mouse model of lethal group B streptococci (GBS) sepsis. Plasma IL-10 levels significantly increased at 24 and 48 h after GBS inoculation. Neutralization of IL-10 with specific antibodies had no effect on lethality. Administration of recombinant IL-10 at 20 or 4 h before challenge, but not at later times, resulted in decreased tumor necrosis factor alpha levels and improved survival. IL-10 could be potentially useful for the treatment of GBS sepsis.

Gastric infection by Helicobacter pylori and antral gastritis in hyperglycemic obese and in diabetic subjects

The aim of this work was to ascertain if diabetes and obesity can affect gastric colonization by Helicobacter pylori. 59 hospitalized subjects with dyspepsia and endoscopic antral gastritis were selected. They were divided into three groups: I) 13 patients with normal body weight and without disease other than gastritis (control group); II) 15 patients with essential obesity of whom 10 had impaired glucose tolerance (IGT); III) 31 patients with type II diabetes mellitus, of whom 14 were obese. Three gastric biopsies were obtained from each patient for histologic examination and H. pylori detection by means of rapid urea test, culture and histological evidence of Helicobacter-Like Organisms (HLO). Age, sex, blood glucose, cholesterol, triglycerides, HDL-cholesterol, basal gastrine, duration of illness, body weight were statistically analysed. Differences between the three groups were not statistically significant. There was a higher prevalence of H. pylori infection both in obese and in diabetic patients with respect to control subjects. Prevalence became still higher in obese patients with impaired glucose tolerance. Among the three tests used for the detection of H. pylori, culture and rapid urea were reliable and specific, while the histologic test was highly sensitive but barely specific. Our data suggest that both obesity and type II diabetes may be associated with an increased incidence of H. pylori-colonization. This could be related to the reduced gastric motility observed in both pathologies and chemical changes in gastric mucosa following non-enzymatic glycosylation processes.

Beneficial effects of pentoxifylline in neonatal rats infected with group B streptococci

Previous studies have indicated that tumor necrosis factor-alpha (TNF-alpha) may play a pathophysiologic role in experimental sepsis by group B streptococci (GBS). We tested the efficacy of some TNF-alpha and eicosanoid inhibitors in a neonatal rat model of GBS disease. The drugs tested included cloricromene, SKF86002, pentoxifylline, CGS8515, ibuprofen and LY203647. None of these compounds were protective against GBS infection, with the exception of pentoxifylline, that produced a moderate enhancement of survival time. Further studies are needed to ascertain if specific inhibitors of TNF-alpha, alone or in conjunction with antibiotics, may be effective as therapeutic agents in neonatal GBS sepsis.

Helicobacter pylori infection: a simplified diagnostic approach

We evaluated the diagnostic accuracy of endoscopic finding of nodular antritis and rapid urease test (RUT) in order to simplify the approach to the diagnosis of Helicobacter pylori (H. pylori) infection. Forty-four consecutive patients (mean age 7.9 yr, range 6-13 yr) referred because of recurrent abdominal pain as the main symptom, were prospectively investigated for the presence of H. pylori. H. pylori positivity or negativity was defined as the concordance of two of the following tests: RUT, microbiologic culture, and histologic examination on bioptic samples. RUT sensitivity was 100%, whereas specificity was 87.5%. The presence of nodular antritis had a sensitivity of 96.4% and specificity of 87.5% in H. pylori infection diagnosis. The predictivity value of combined RUT and nodular antritis, whether positive or negative, was 100%. Only in case of discordance do we suggest the utilization of other expensive tools for diagnosis of H. pylori infection.

Adherence of Staphylococcus strains to human urinary and buccal epithelial cells

91 strains of Staphylococci belonging to different species were investigated for their adhesive capacity to urinary and buccal human epithelial cells. Furthermore the adherence of the same bacterial strains was evaluated in relation with their methicillin-sensitive and methicillin-resistant properties. S. aureus showed an high adhesion to buccal and urinary cells; S. saprophyticus and S. epidermidis attached mainly to uroepithelial cells and to buccal cells, respectively. Bacterial strains, either sensitive or resistant to methicillin antibiotic, did not exhibit significant differences of adhesive capacity.

In vitro susceptibility of Salmonella strains to cefotetan and other cephalosporins

The in vitro activity of cefotetan, a recently developed cephamycin, is investigated by Minimum Inhibitory Concentration (MIC) and by the agar diffusion method against 212 strains of Salmonella (36 species). Cefotetan shows good activity against all strains of Salmonella tested and it is more active than other cephalosporins, in particular, on S. wien.

Comparison of six systems for the identification of Enterobacteriaceae

Six widely used commercial systems for Enterobacteriaceae identification (API 20 E, API 10, Enterotube, Enterotube II, Micro-ID and Minitek) were evaluated at the same time by testing 611 organisms. Conventional media were used for comparison. API 20 E, Enterotube II and Micro-ID were highly accurate and identified about 91% of the strains to the species level. The remaining organisms required additional tests and only a small minority was misidentified. Percentages of correct identification to the species level were 87.2 for Enterotube, 74.9 for API 10 and 67.1 for Minitek. Enterotube, Enterotube II and Micro-ID were, in our hands, the easiest systems to operate.

[Listeria monocytogenes action on viral T8 epithelioma growth]

Effects of Listeria monocytogenes on normal and tumor-bearing rats were evaluated. Inhibition of T8 tumor and its metastases in tumor-bearing rats treated with L. monocytogenes was observed. Macrophage phagocyte functions, depressed in tumor bearing rats, was restored by L., monocytogenes. In particular, a dissociation between different macrophages functions in tumor-bearing rats was observed.