Is there an association between Helicobacter pylori cytotoxin Cag A seropositivity and risk for gastric cancer?

BACKGROUND: Since discovered in 1990, Cag A, a protein expressed by specific strains of Helicobacter pylori, was thought able to explain why only a few Helicobacter infected patients develop peptic diseases and gastric cancer. However, clinical trials provide discordant results. MATERIALS AND METHODS: In this study we evaluate Helicobacter pylori and Cag A seropositivity in 35 cancer affected patients, in 36 gastritis affected patients and in 40 healthy blood donors by means of two commercially available fluorescence enzyme-immunoessay (ELISA). RESULTS: Odds ratios determination strongly suggests that Cag A bearer Helicobacter strains play a pathogenetic role in gastric diseases (OR 4.23, 95% CI 3.22-5.24 for cancer versus healthy volunteers, OR 3.2, 95% CI 2.19-4.21 for gastritis versus asymptomatic patients), but is unable to demonstrate a direct carcinogenic activity (cancer-gastritis difference is not significant: OR 1.32, 95% CI 0.39-1.25). CONCLUSIONS: Cag A seropositivity can be considered a risk factor for peptic disease, and only indirectly for gastric carcinoma. The paper also discuss some sampling, laboratory and statistical bias that can explain a wide eterogenity of the results reported in the literature.

Mycobacterium genavense in AIDS patients, report of 24 cases in Italy and review of the literature.

Mycobacterium genavense is a frequently missed agent of disseminated disease in AIDS patients. The increasing frequency with which such organism is being isolated in Italy suggested a comparison of local survey with data reported in literature. Isolates presumed to belong to the species M. genavense were centralized and identified by means of genomic sequencing and/or HPLC analysis of cell wall mycolic acids; clinical data were obtained from relevant patients' record and collected using a proper questionnaire. In 24 cases in which this organism has been isolated in Italy M. genavense was grown, prevalently from blood, in liquid medium after an average of six weeks of incubation. In overwhelming majority, patients were males, presented other opportunistic diseases and were characterized by very low CD4+ counts (average 23/microl); most frequent symptoms were fever, anemia and weight loss. All but two patients, who died before the mycobacterial infection was diagnosed, were treated with at least three drugs; the mean survival was close to one year. A review of literature reports revealed a wide overlapping of clinical and microbiological features.

Mycobacterium malmoense in Italy: the modern Norman invasion?

The isolation of Mycobacterium malmoense has for a long time been restricted to few countries of Northern Europe; reports from countries other than Sweden, Great Britain and Finland are rare and the first Italian case report has been published in 1995. Since 1988, however, fifteen strains of M. malmoense have been isolated in Italy, eleven of which in the last two years; of these, ten appeared clinically significant on the basis of medical records. The susceptibility of the strains and the role of high performance liquid chromatography of cell wall mycolic acids for a reliable identification are discussed.

Detection and identification of Mycobacterium avium in the blood of AIDS patients by the polymerase chain reaction.

One hundred fifty-three blood samples from patients positive for the human immunodeficiency virus (HIV) were analyzed by polymerase chain reaction (PCR) to detect the presence of Mycobacterium avium. Samples were collected from patients who also had blood cultures performed by a radiometric method. Blood samples were centrifuged on a Ficoll-Hypaque gradient to purify peripheral blood mononuclear cells. The purified cells were washed and incubated with a resin, boiled to release mycobacterial DNA, and then amplified. Polymerase chain reaction products were detected by a nonisotopic method. A 123 base-pair (bp) insertion sequence, namely IS6110, from Mycobacterium tuberculosis complex was also included in the reaction as an internal control of Taq polymerase activity to exclude the presence of enzyme inhibitors. This IS6110 fragment can be distinguished from the 383 bp target product on ethidium bromide-stained agarose gel and may also be used in a colorimetric assay. Such results were compared with the results of culture and indicated that the assay is as sensitive as bacteriological methods, though faster.

Characterization of an isolate of the newly described species Mycobacterium interjectum.

The phenotypic features of a clinical isolate of the new species Mycobacterium interjectum, identified on the basis of its 16S rRNA gene sequence, are compared with those of the type strain. The differentiation of M. interjectum from Mycobacterium gordonae or Mycobacterium scrofulaceum is not achievable on the basis of phenotypic traits usually tested for mycobacterial speciation, but it can be reached by 16S rRNA gene sequencing or by high performance liquid chromatography (HPLC) of cell wall mycolic acids. The former reveals sequence identity with the signature region of the type species, and the latter yields a profile which is easily differentiated from those of the other two species. The unique HPLC profile of M. interjectum is reported here for the first time and so are the MICs of a wide spectrum of drugs.

Diagnosis of bronchopulmonary infections by quantification of microflora.

The quantification of bacteria and fungi in sputum or bronchoaspirate is of clinical value for the diagnosis of respiratory tract infections. We have developed an easy method to count the micro-organisms in patients with respiratory tract infections. This consists of the quantification of micro-organisms by subsequent streakings of a calibrated loop on agar. The correlation between microbiological quantitative data and the clinical status of patients with lower respiratory tract infections is discussed. The data seem to indicate that certain bacteria present in sputum or bronchoaspirate above a certain concentration may be responsible for lower respiratory tract infections. In patients with immunological disorders or chronic pathologies even lower concentrations of micro-organisms in bronchial secretions probably are enough to cause infections. The advantage of this counting method of the microbic species from the respiratory tract consists of their quantification: thus we can attribute an etiological role to a high concentration of the germs, while micro-organisms at low concentrations are probably contaminants. By this method isolated colonies are obtained after 12-18 hours. The bacterial quantification, by respiratory samples examination of the same patient in the following days, allows us to evaluate the efficacy of antibacterial therapy, producing a reduction of bacterial concentration.

Simultaneous catheter replacement-removal during infectious complications in peritoneal dialysis.

The aim of this study was to verify whether the replacement of the peritoneal catheter in a single operation and during infectious complications of peritoneal dialysis is effective and safe. Sixty-eight infectious complications refractory to appropriate antibiotic therapy were treated by this technique: 26 tunnel infections, 22 peritonitis-complicating tunnel infections, 12 refractory peritonitis, and 8 recurrent peritonitis. Operations were successful in all cases of tunnel infection and recurring peritonitis, and in all cases but one of peritonitis-complicating tunnel infection. Ten failures occurred among the 12 catheters removed for refractory peritonitis. Microorganisms cultured in these 10 failures were: Fungi (3 cases), Mycobacterium (2 cases), Pseudomonas (2 cases), Acinetobacter (1 case), Acinetobacter+Pseudomonas (1 case), and Enterococcus (1 case). Complications were 3 one-way obstructions and 2 external dialysate leaks. This study supports the simultaneous catheter replacement-removal procedure during infectious complications of peritoneal dialysis (PD) with the exception of refractory peritonitis; this technique spares the patient the temporary vascular access, the shift to hemodialysis, and a second operation to insert a new catheter. There are few complications.

Rapid methods for microbial diagnosis of mycobacterial infections.

The Authors describe their experience in rapid diagnosis of mycobacterial infections using a combination of a radiometric blood culture (Bactec 13 A) and a nucleic acid hybridization system (Gen probe, Accuprobe) to detect and identify Mycobacteria. They found out that a high number of septicaemias in HIV positive patients are due to Mycobacterium avium, while in HIV negative subjects Mycobacterium tuberculosis is the most frequent mycobacterium.

Antibodies to HTLV-1-2, HIV-1 and HIV-2 in syphilitic patients.

Antibodies to human immunodeficiency virus type 1 (HIV-1) and type 2 (HIV-2) and to human T-cell leukemia virus (HTLV-1) were investigated by ELISA, Western blot and radioimmunoprecipitation (RIPA) assay in 318 sera (191 males and 127 females) obtained from syphilitic patients. The sera from 10% of the males and 3.1% of the females were positive for HIV-1. None of the sera contained antibodies to HIV-2. Antibodies to HTLV-1-2 were present in the sera of 7.1% of the males and 4.8% of the females who were seronegative for HIV. Five out of 24 (20.8%) HIV-1 positive subjects had antibodies to HTLV-1-2 as well. Sera from another group of 58 syphilitic patients (38 males and 20 females in the Anti-Venereal Disease Department), seronegative for HIV-1 and HIV-2, who denied both i.v. drug abuse and blood transfusion, were investigated in the same manner. None of the males had antibodies to HTLV-1-2, while 2 females (10%) were positive.

A multicentre study to evaluate the effect of sulbactam/ampicillin combination on anaerobic micro-organisms.

Ampicillin combined with the beta-lactamase inhibitor sulbactam was compared with ampicillin alone, cefoxitin and metronidazole against 569 clinical strains of anaerobic organisms. The strains included 289 species of Bacteroides, 160 strains of Clostridium and 120 strains of various species of Streptococcus/Peptostreptococus, Fusobacterium, Veillonella, Eubacterium, Bifidobacterium, Actinomyces and Propionibacterium. Sulbactam/ampicillin was as effective as cefoxitin and metronidazole against all anaerobic species tested, inhibiting more than 90% of strains at the breakpoints (16, 32 and 32 mg/l, respectively). Sulbactam/ampicillin was also significantly more active than ampicillin against strains of Bacteroides, the minimal inhibitory concentration being at least four-fold lower. In contrast, the activity of the combination did not differ from that of ampicillin alone against Fusobacterium species and Gram-positive rods and cocci.

Natural antibodies to IFN-gamma in man and their increase during viral infection.

Natural antibodies to IFN-gamma were found in healthy individuals ranging from newborn babies to adults and, at higher levels, in patients suffering from different viral infections. During a viral infection, the titer of anti-IFN-gamma antibodies was observed to be correlated with the stage of the disease. Antibodies specific to IFN-gamma were affinity purified both from sera taken from healthy individuals and sera from viral-infected patients, by using a rIFN-gamma-coupled CNBr-activated Sepharose 4B column. The antibodies were found to be of the IgG class, and maintained their ability to bind rIFN-gamma. They were then tested for neutralizing activity and none of the IgG preparations we analyzed impaired the antiviral activity of rIFN-gamma. This finding suggests that the antigenic determinants recognized by these antibodies on the IFN-gamma molecule are located outside the site, on the IFN-gamma molecule, responsible for its antiviral activity.

Antibacterial activity of the new carbapenem meropenem (SM-7338) against clinical isolates.

The in vitro antibacterial activity of the new carbapenem antibiotic meropenem (SM-7338) against 567 clinical isolates was evaluated. SM-7338 exhibited activity against a broad spectrum of organisms, including aerobes and anaerobes, and was superior to the other beta-lactam drugs tested (piperacillin, cefotaxime, ceftazidime, ceftriaxone, cefoxitin). SM-7338 was more active than imipenem, gentamicin and amikacin against Enterobacter cloacae and Pseudomonas aeruginosa. SM-7338 was less potent than imipenem against staphylococci and enterococci, but the activity of the two antibiotics against anaerobes was similar. SM-7338 and imipenem showed a high bactericidal activity at a concentration of 2-4 x MIC.

Rufloxacin (MF-934): in vitro and in vivo antibacterial activity.

Rufloxacin (MF-934) is a new quinolone which shows in vitro antibacterial activity against E. coli, Salmonella, Klebsiella, Proteus and Staphylococcus spp. Lower in vitro activity was observed with Pseudomonas, Serratia, Enterobacter and the streptococci group D. The antimicrobial activity of MF-934 in vitro is higher than that of nalidixic acid but lower than that of ciprofloxacin, ofloxacin, pefloxacin or norfloxacin. The protective effects of MF-934 in systemic infections in mice are lower than those of ciprofloxacin and ofloxacin. In respiratory infections in rats and in subcutaneous infections in guinea-pigs, the protective effects of MF-934 are of the same order as ciprofloxacin and ofloxacin. This is probably due to the pharmacokinetic properties of MF-934, i.e. the long half-life and tissue concentrations higher than plasma levels.

Evaluation of BACTEC system for urine culture screening.

We compared urine culturing performed by the calibrated loop method with a screening system (BACTEC). A total of 852 urine specimens were examined by both the conventional loop method and the BACTEC system. With the loop method, 193 (22.6%) urine samples were positive, whereas with the BACTEC system, 185 (21.7%) were positive (sensitivity, 96.01%). At a breakpoint of 10(4) CFU/ml, eight false-negatives were detected (sensitivity, 87.09%), and at a breakpoint of 10(5) CFU/ml, four false-negatives were observed (sensitivity, 97.6%). The specificity of the BACTEC system was 100%. We propose the BACTEC method as an effective alternative to the other growth-dependent screening tests for bacteriuria.