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Biomedical subjects

R Cisterna

Publications and source records attributed to R Cisterna.

At least 55 records · Page 3Linked to original sources
PubMed1996

Relationship between outer membrane protein profiles and resistance to ceftazidime, imipenem, and ciprofloxacin in Pseudomonas aeruginosa isolates from bacteremic patients.

Outer membrane protein (OMP) profiles of 122 Pseudomonas aeruginosa isolates recovered from the blood of bacteremic patients were analyzed to relate alterations in the expression of OMPs with porin activity to resistance to imipenem, ceftazidime, and ciprofloxacin. Imipenem-resistant isolates lacked or expressed reduced amounts of porin OprD. In contrast, alterations of OMP profiles were absent in most ceftazidime-resistant isolates. Six of 12 ciprofloxacin-resistant isolates had normal OMP profiles. The remaining isolates showed alterations in the expression of either OprC, OprF, or OprD. In addition, imipenem- and ceftazidime-resistant isolates displayed a beta-lactamase activity compatible with that of a group 1 chromosomal cephalosporinase.

Anti-Infective Agents↗
PubMed1996

Detection of hepatitis C virus RNA in serum and peripheral blood mononuclear cells in patients with chronic hepatitis C treated with interferon alpha.

PCR was used to detect hepatitis C virus (HCV) RNA in serum and peripheral blood mononuclear cells (PBMCs) for evaluation of a six-month course of interferon therapy in 18 patients with histologically confirmed chronic hepatitis C. At follow-up six months after the end of therapy positive-stranded (genomic) and negative-stranded (anti-genomic, presumptive replicative intermediate) HCV RNA could be detected in PBMCs of all ten patients who either did not respond to therapy or suffered a relapse; genomic strand RNA was detected in five patients who responded but then relapsed. The study confirms that interferon therapy leads to inhibition of HCV replication but not eradication of the virus. Persistence of the virus at extrahepatic sites may explain its reactivation after cessation of interferon therapy.

Adult↗
PubMed1996

Emergence of resistance to beta-lactam agents in enterobacteriaceae species with group I beta-lactamases in Spain.

The contribution of induction and stable derepression of chromosomal group I beta-lactamases to beta-lactam antibiotics resistance was studied in clinical isolates of Enterobacteriaceae, collected from patients treated with these antibiotics. Multiple isolates of the same species from the same patient were characterized by different typing methods. Sonicated extracts of cells were assayed for chromosomal and plasmid-mediated beta-lactamases by isoelectric focusing and cloxacillin inhibition studies. The specific beta-lactamase activity, basal and induced with cefoxitin, was determined to differentiate strains with inducible or derepressed production of the enzyme. Induction of beta-lactamases was performed in each strain against the beta-lactams used in the therapy of each patient. Older penicillins resulted in a moderate to strong increase in beta-lactamase activity, whereas the results obtained with first-generation cephalosporins were species dependent. Expanded-spectrum cephalosporins were weak inducers of beta-lactamases. Indeed, the use of cefotaxime for treatment preceded the appearance of strains that produced chromosomal group I beta-lactamases constitutively. These strains showed a remarkable reduction in sensitivity to ureidopenicillins, carboxipenicillins, expanded-spectrum cephalosporins, and monobactams, but not to carbapenems.

Anti-Bacterial Agents↗
PubMed1996

Serratia rubidaea as an invasive pathogen.

Serratia rubidaea biotype 1 was isolated from the bile and blood of a patient with a bile tract carcinoma obstructing the common bile duct and who underwent invasive procedures. The infection was cleared after adequate treatment with antibiotics.

Anti-Bacterial Agents↗
PubMed1995

Association between HIV and other DNA viruses in vitro.

To investigate the association of human immunodeficiency virus (HIV) with various DNA viruses, including hepatitis B virus (HBV), cytomegalovirus (CMV) and Epstein-Barr virus, (EBV), simultaneous detection of HIV p24 antigen, HBV surface antigen and DNA, CMV-DNA and EBV-DNA expression was performed in phytohemagglutinin-stimulated peripheral blood mononuclear (PBMC) culture supernatants obtained from 54 individuals at risk for HIV infection. HIV expression in PBMC culture supernatants never occurred alone; expression of other viruses was always detected in the 24 samples expressing HIV antigen in vitro. Furthermore, in 16 patients expression of other viruses was detected without HIV expression, and in 14 patients none of the tested viruses were detected. These results indicate a strong association between the presence of HIV antibody and expression of DNA viruses in vitro (p = 0.0001). The coexpression of these viruses could be related to the evolution of HIV infection and AIDS.

Cells, Cultured↗
PubMed1995

Emergence of resistance to beta-lactam agents in Pseudomonas aeruginosa with group I beta-lactamases in Spain.

The contribution of induction and stable derepression of chromosomal class I beta-lactamases to beta-lactam antibiotic resistance was studied in clinical isolates of Pseudomonas aeruginosa collected from patients treated with beta-lactam antibiotics. Multiple isolates from the same patient were characterized by O-serotyping as a primary screen, combined with pyocin typing. Sonicated extracts of cells were assayed for chromosomal and plasmid-mediated beta-lactamases by isoelectric focusing and cloxacillin inhibition studies. The specific beta-lactamase activity, basal and induced, with cefoxitin was determined to differentiate strains with inducible or derepressed production of the enzyme. Beta-lactamase induction was performed in each strain against the beta-lactam agents used in the therapy of each patient. The observations showed that induction against older penicillins such as penicillin, amoxicillin, and amoxicillin/clavulanate resulted in a moderate to strong increase in beta-lactamase activity, whereas the results obtained with first-generation cephalosporins varied with the beta-lactam agent tested. Third-generation cephalosporins were weak inducers of beta-lactamases, and their use as therapy preceded the appearance of strains that produce chromosomal group I beta-lactamases constitutively. These strains showed a remarkable reduction in sensitivity to ureidopenicillins, carboxipenicillins, third-generation cephalosporins, and monobactams, but not to carbapenems.

Anti-Bacterial Agents↗
PubMed1995

Five-year survey of cefotaxime resistance in Spain.

During 1991-1995 a Spain collaborative study group surveyed the resistance to cefotaxime both in community as well as in hospital isolates of bacteria. The isolates tested during the study period of 5 years were 813, 875, 3631, 3184, and 3050 strains, respectively. Antimicrobial activity of cefotaxime was assayed by broth or agar microdilution, in accordance with criteria of the National Committee of Clinical Laboratory Standards (NCCLS). Cefotaxime resistance included 2.5% of all isolates: 2.6% Enterobacteriaceae, 1.7% Streptococcus pneumoniae, 0.5% Haemophilus influenzae, 0.0% Haemophilus spp., and 0.0% Moraxella catarrhalis. The overall incidence of resistance to cefotaxime decreased fro member of Enterobacteriaceae from 3.6% in 1991 to 2.5% in 1995. The incidence of resistance varied with the species and was highest in Enterobacter and in Citrobacter freundii.

Bacterial Infections↗
PubMed1994

Detection of hepatitis B virus DNA and determination of surface antigen expression in peripheral blood mononuclear cells from patients with AIDS.

The polymerase chain reaction (PCR) was used to analyze the presence of hepatitis B virus (HBV) DNA in serum and peripheral blood mononuclear cells (PBMCs) from 20 patients with AIDS with and without conventional HBV serological markers. DNA sequences of HBV were detected in PBMCs from 13 patients, nine of whom were positive for anti-HBc only and four of whom were also positive for anti-HBs. When PBMCs from patients were activated in culture with phytohemagglutinin, the presence of HBsAg could be detected in the culture supernatants from four of 13 patients with HBV DNA in their PBMCs; for two of the four, HBV DNA could also be detected in the culture supernatant after DNA amplification. It was observed that HBV DNA sequences found in PBMCs can be reactivated by mitogen stimulation in some HIV-1 infected patients.

Acquired Immunodeficiency Syndrome↗
PubMed1994

Detection of human immunodeficiency virus type 1 by PCR before seroconversion in high-risk individuals who remain seronegative for prolonged periods.

HIV-1 seronegative patients at high risk for HIV infection were followed up. In 1990 PCR was positive for HIV DNA sequences in samples of 17 seronegative patients who continued to report for surveillance of HIV infection. There was clear evidence of seroconversion in four of these 17 seronegative patients, while in one patient an indeterminate result for HIV was repeatedly obtained in different samples. The other 12 patients continue to be seronegative without any evidence of HIV infection except the presence of provirus in peripheral blood mononuclear cells. It is important to apply the PCR technique together with tests to detect other virological and immunological markers, in order to identify seronegative carriers and thus avoid HIV transmission by them.

Adult↗
PubMed1994

In vitro activity of biapenem against beta-lactamase producing Enterobacteriaceae.

The activity of biapenem was compared with that of imipenem and cefotaxime against 108 strains of beta-lactamase producing Enterobacteriaceae. Biapenem and imipenem were very active, inhibiting 90% of the strains at a concentration of 0.5 microgram/ml. Both carbapenems were very active against plasmidic beta-lactamase producers, with MIC90s below 1 microgram/ml. However, the MIC90 of biapenem for cephalosporinase producers was 1 microgram/ml. Against strains producing extended-spectrum beta-lactamases, biapenem exhibited better activity against TEM-type producers (MIC90 0.25 microgram/ml) than against SHV-type producers (MIC90 0.5 microgram/ml). Overall, the in vitro antibacterial activity of biapenem is similar to that of imipenem.

Cefotaxime↗
PubMed1994

Multicenter evaluation of a fully automated screening test, VIDAS HIV 1 + 2, for antibodies to human immunodeficiency virus types 1 and 2.

A multicenter study was done to evaluate the sensitivity, specificity, and efficiency of a new screening test for the simultaneous detection of human immunodeficiency virus type 1 and 2 (HIV-1 and HIV-2) antibodies. The VIDAS HIV 1 + 2 (bioMérieux, Marcy l'Etoile, France) is a fully automated enzyme-linked fluorescent immunoassay that uses synthetic peptides from immunodominant regions of gp41 of HIV-1 and gp36 of HIV-2 as antigens. A total of 2,984 samples were evaluated with this system in six different laboratories, and the results were compared to those obtained with other enzyme-linked immunosorbent assays. The VIDAS HIV 1 + 2 assay showed a very good performance in terms of sensitivity (100%) and specificity (99.6%), requiring minimal manipulation and short incubation time (32 min) to give results similar to or better than those of the other enzyme-linked immunosorbent assays used for screening.

Enzyme-Linked Immunosorbent Assay↗
PubMed1994

[Detection of virulence factors using DNA probes in uropathogenic strains of Escherichia coli].

BACKGROUND: There are several bacterial determinants that contribute to the onset of urinary tract infection by E. coli. The present study focuses on some of the virulence factors considered to be most important, as P fimbriae, the siderophore aerobactin and bacterial capsule, which were studied among 123 uropathogenic E. coli strains isolated from outpatients from the Basque Community. METHODS: Virulence factors were detected using Molecular Biology techniques, namely DNA hybridization to specific probes prepared in our laboratory. RESULTS: When probe pap2, specific for fimbrial adherence was used, 36.5% of the strains showed positive hybridization, and 66 and 73% of the strains hybridized to probes for aerobactin and common capsule region, respectively. CONCLUSIONS: We believe that this technology provides a very useful tool for rapid and easy screening of strains harbouring different virulence factors. Nevertheless, the fact that these methods detect genetic determinants that are not always being expressed must be borne in mind.

Bacterial Adhesion↗
PubMed1994

Detection of circulating antigens in the diagnosis of acute toxoplasmosis.

Using an enzyme-linked immunosorbent assay, we have found circulating antigens of Toxoplasma gondii in three models of murine toxoplasmosis: mice infected with trophozoites of the RH strain (acute toxoplasmosis), the Beverley strain (subacute toxoplasmosis), and the T626 strain (chronic toxoplasmosis). Circulating antigens were detected 48 hr after infection in the mice infected with the RH strain, and all mice had antigenemia by the fourth day. In those infected with the Beverley strain, circulating antigens were detected from the second day after inoculation until the end of the study, with a peak (71% of the infected mice) on day 10. Of those infected with the T626 strain, 40% had antigenemia at 13 days after infection. The detection of circulating antigens in serum is directly related to the presence of toxoplasmosis in the acute phase in the three models studied and, therefore, may prove very useful in the rapid diagnosis of this disease.

Acute Disease↗