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Biomedical subjects

G Fadda

Publications and source records attributed to G Fadda.

At least 91 records · Page 5Linked to original sources
PubMed1999

Simple and rapid identification of different species of Mycobacteria by PCR.

A simple polymerase chain reaction (PCR) assay for rapid identification of different species of mycobacteria was developed. This PCR is based on the use of conserved sequences to amplify the genome of several mycobacterial species. The amplification patterns obtained were specific and reproducible for the species tested. In particular, we could identify Mycobacterium tuberculosis and Mycobacterium bovis (both produced the same pattern), Mycobacterium avium, Mycobacterium kansasii, Mycobacterium xenopi, Mycobacterium chelonae, Mycobacterium peregrinum, Mycobacterium fortuitum, Mycobacterium gordonae and Mycobacterium smegmatis. Moreover, due to the numerous copies of the target sequences present in the genome, the PCR showed a very high level of sensitivity.

AIDS-Related Opportunistic Infections↗
PubMed1999

Candidemia in HIV-infected subjects.

The epidemiological features of 37 episodes of candidemia in HIV-infected subjects were analysed in a retrospective matched case-control study conducted over an 8-year period (1990-1997). Univariate analysis identified eight risk factors that were significantly associated with candidemia (P<0.05): i) use of central venous catheters; ii) administration of total parenteral nutrition; iii) previous antifungal therapy; iv) previous therapy with glycopeptides; v) presence of oral/ esophageal candidiasis; vi) concomitant bacterial infections; vii) neutropenia; and viii) concomitant AIDS dementia complex. Stepwise logistic regression analysis revealed that the only independent risk factor for developing candidemia was the use of central venous catheters (P = 0.0001). Candida albicans was the most frequently isolated pathogen, accounting for 18 (48%) episodes of candidemia, followed by Candida tropicalis (19%) and Candida glabrata (11%). The crude mortality rate was 62%. On univariate analysis concomitant opportunistic infections, presence of non-Candida albicans species of Candida and neutropenia were shown to be predictive of death. Multivariate analysis revealed that the presence of non-Candida albicans strains of Candida was the only significant factor associated with a worse prognosis (P = 0.001). In conclusion, candidemia appears to be more common in patients with advanced HIV disease. Of the factors which influenced the onset of candidemia, use of central venous catheters seemed to be the most important one.

AIDS-Related Opportunistic Infections↗
PubMed1999

Application of molecular methods for detection and transmission analysis of mycobacterium tuberculosis drug resistance in patients attending a reference hospital in Italy.

A molecular analysis of drug-resistant isolates of Mycobacterium tuberculosis was done in a population with a high prevalence of human immunodeficiency virus infection. Seventy-one consecutive isolates were tested for genotypic resistance to isoniazid, rifampicin, streptomycin, and ethambutol by polymerase chain reaction-single strand conformation polymorphism analysis and automated sequencing of target regions. Phenotypic and genotypic resistance to isoniazid, rifampicin, streptomycin, and ethambutol were detected in 23.4%, 11.2%, 7%, and 5.6% of isolates and in 87%, 88%, 40%, and 100% of resistant isolates, respectively. Specificity was 100% for all target regions. When rpoB, katG, and ahpC mutation analysis were combined, 86% of resistant isolates to any drug were identified. No mutations in inhA were found in isoniazid-resistant isolates. Molecular detection of drug resistance, particularly for isoniazid and rifampicin, may represent a sensitive and very specific technique. The strategy of selecting rpoB, katG, and ahpC to quickly identify most resistant isolates, with a relevant saving of resources, is warranted.

Drug Resistance, Microbial↗
PubMed1999

HHV-8/KSHV is not associated with AIDS-related primary central nervous system lymphoma.

Primary central nervous system lymphoma (PCNSL) is a major complication of the late stages of human immunodeficiency virus (HIV) disease. Epstein Barr virus (EBV) infection is the only genetic lesion consistently associated with this neoplasia. Recently, it has been proposed that the pathogenesis of AIDS-related PCNSL (AIDS-PCNSL) may be associated with infection by human herpesvirus-8/Kaposi's sarcoma associated herpesvirus (HHV-8/KSHV), although at present such association remains controversial. In order to conclusively assess the link between HHV-8/KSHV infection and AIDS-PCNSL, we performed a comprehensive study based on multiple molecular assays on cerebral tissues and cerebrospinal fluid (CSF) as well as specific immunologic assays on patients' sera. A well characterized panel of 33 Italian patients with AIDS-PCNSL and 13 controls with other HIV-related brain focal diseases from the same geographical area was analyzed. No signs of HHV-8/KSHV infection were detected in cerebral tissues by single-step PCR. Cerebral tissues of all AIDS-PCNSL scored negative for HHV-8/KSHV DNA sequences also by nested PCR, with the exception of one single patient who was simultaneously affected by Kaposi's sarcoma. All CSF samples analyzed were consistently devoid of HHV-8/KSHV sequences by molecular assays. By serologic assays, detecting both latent and lytic HHV-8/KSHV antigens, a specific immunoreactivity was observed in 16/33 (48%) AIDS-PCNSL and in 6/13 (46%) controls (P = 0.88). A significant correlation with HHV-8/KSHV serum reactivity was seen with a homosexual route of HIV transmission (P = 0.018), but not with the presence of AIDS-PCNSL. The results of our analysis conclusively assess that HHV-8/KSHV infection is not a feature of AIDS-PCNSL.

Antibodies, Viral↗
PubMed1999

Different strategies for molecular differentiation of Mycobacterium bovis strains isolated in Sardinia, Italy.

Different genetic markers were used to analyze 22 Mycobacterium bovis strains isolated from cattle in Sardinia and one human isolate. IS6110 DNA fingerprinting differentiated the strains into six patterns, whereas with enterobacterial repetitive consensus sequence primers produced seven clusters. PCR ribotyping followed by digestion with HaeIII and PvuII produced five and seven patterns, respectively. PCR with the (GTG)5 oligonucleotide primer showed the best discriminatory power, generating eight clusters among the strains analyzed.

Animals↗
PubMed1999

Differentiation of Vibrio alginolyticus strains isolated from Sardinian waters by ribotyping and a new rapid PCR fingerprinting method.

We investigated the usefulness of a novel PCR fingerprinting technique, based on the specific amplification of genomic regions, to differentiate 30 Vibrio alginolyticus strains isolated in Sardinian waters. The different profiles obtained were scanned and analyzed by a computer program in order to determine genetic relationships. The results were then compared with the patterns obtained by ribotyping with HindIII, KpnI, and XbaI restriction enzymes. PCR fingerprinting could differentiate the strains analyzed into 12 different patterns, whereas ribotyping with XbaI, which produced the highest number of patterns, generated only 7 different profiles. This study revealed the superior discriminative power of the proposed technique for the differentiation of related V. alginolyticus strains and the potential use of PCR fingerprinting in epidemiological studies.

Bacterial Typing Techniques↗
PubMed1999

Human herpesvirus 8 seroprevalence and evaluation of nonsexual transmission routes by detection of DNA in clinical specimens from human immunodeficiency virus-seronegative patients from central and southern Italy, with and without Kaposi's sarcoma.

In order to investigate the seroprevalence of human herpesvirus 8 (HHV-8) infection in central and southern Italy, sera from human immunodeficiency virus (HIV)-seronegative subjects, with and without Kaposi's sarcoma (KS), were analyzed by immunofluorescence assay, using BC-3, a cell line latently infected with HHV-8. High titers of antibody against HHV-8 lytic and latent antigens were detected in all 50 KS patients studied, while in 50 HIV-seronegative subjects without KS, 32 (64%) were found positive for HHV-8 antibodies. Titers in the sera of these patients were lower than those for KS patients. This data suggests that HHV-8 infection is not restricted to KS patients and that the prevalence of HHV-8 infection in the general population may be correlated with differing rates of prevalence of KS in different parts of the world. In view of these findings, possible nonsexual transmission routes were evaluated. Nested PCR was used to test for the presence of HHV-8 DNA in saliva, urine, and tonsillar swabs from KS and non-KS patients. In KS patients, 14 out of 32 tonsillar swabs (43.7%), 11 out of 24 saliva samples (45.8%), and just 2 out of 24 urine samples (8.3%) tested positive for HHV-8 DNA. In the control group, on the contrary, none of the 20 saliva and 20 urine specimens was positive for HHV-8 DNA; only 1 out of 22 tonsillar swabs gave a positive result. This data supports the hypothesis that HHV-8 infects the general population in a latent form. The reactivation of viral infection may result in salivary shedding of HHV-8, contributing to viral spread by nonsexual transmission routes.

Antibodies, Viral↗
PubMed1999

PCR-restriction enzyme analysis for detection of Candida DNA in blood from febrile patients with hematological malignancies.

Blood samples were drawn daily from 72 patients who had hematological malignancies, neutropenia, and fever and who had failed to respond to broad-spectrum antibiotics. Each sample was used for conventional fungal blood cultures and for detection and identification of Candida DNA by a PCR method with subsequent restriction enzyme analysis (REA) recently developed in our laboratory. The PCR method was able to detect five CFU of Candida spp. per ml of blood, and subsequent REA of the amplicons allowed the identification of the Candida species most commonly implicated in cases of candidiasis. Thirty-one patients were PCR-REA positive, and four of these patients were also culture positive. The ultimate diagnosis for 13 of these patients and 1 patient who was PCR-REA negative was disseminated candidiasis (confirmed by clinical data, multiple cultures, histology, autopsy, and/or ultrasonographic evidence of hepatosplenic candidiasis). The molecular method is significantly more sensitive than conventional fungal blood cultures and has a high negative predictive value (97.5%) for the development of disseminated candidiasis in neutropenic patients.

Amphotericin B↗
PubMed1999

Molecular and epidemiological characterization of vaginal Saccharomyces cerevisiae isolates.

Although vaginitis caused by Saccharomyces cerevisiae is extremely rare, in recent years we have experienced an increasing frequency of S. cerevisiae isolation from the vaginas of fertile-age women. In order to investigate the epidemiology of these vaginal infections, a total of 40 isolates of S. cerevisiae derived from symptomatic and asymptomatic women were characterized by two DNA typing approaches, named ribosomal DNA (rDNA) hybridization and Ty917 hybridization, based on the Southern blotting technique. After transfer, the polymorphic DNA restriction fragments were hybridized with the entire repeat of S. cerevisiae rDNA for one method and with the entire sequence of the Ty917 retrotransposon for the other. After elaboration with computer-assisted analysis, the results of each method showed that Ty917 hybridization is endowed with a discriminatory power higher than that of rDNA hybridization. With the Ty917 hybridization method, all of the S. cerevisiae isolates tested appeared very heterogeneous, with the exception of those collected from individual patients with recurrent vaginitis. This allowed us to exclude a possible common source of infection while the high relatedness among S. cerevisiae sequential isolates from recurrent-vaginitis patients could suggest a pattern of relapse rather than frequent reinfection.

Adult↗
PubMed1999

Molecular characterization and antibiotic susceptibilities of ocular isolates of Staphylococcus epidermidis.

Nineteen isolates of Staphylococcus epidermidis from patients with ocular infections were analyzed. Patients were selected in retrospect, by choosing cases in which S. epidermidis was the sole isolate. Twelve different patterns were obtained after hybridization with a probe with high-level homology to insertion sequences found in S. epidermidis. Susceptibilities to penicillin, methicillin, gentamicin, tetracycline, erythromycin, ciprofloxacin, vancomycin, and teicoplanin were determined. Six strains were resistant to three or more antibiotics.

Anti-Bacterial Agents↗
PubMed1999

Identification and antibiotic susceptibility of coagulase negative staphylococci isolated in corneal/external infections.

AIMS: To identify and determine antibiotic susceptibility of coagulase negative staphylococci (CoNS) isolated from patients with chronic blepharitis, purulent conjunctivitis, and suppurative keratitis. METHODS: A retrospective review of all culture positive cases of chronic blepharitis, purulent conjunctivitis, and suppurative keratitis between July 1995 and December 1996 was performed. Cases in which CoNS were the sole isolates were analysed. Species identification was performed by using a commercially available standardised biochemical test system. Antibiotic susceptibility to penicillin, gentamicin, tetracycline, erythromycin, ciprofloxacin, and teicoplanin was determined by agar disc diffusion (Kirby-Bauer method). Teicoplanin resistance was confirmed by agar dilution. RESULTS: 42 Staphylococcus epidermidis, four S warneri, three S capitis, two S hominis, one each of S xylosus, S simulans, S equorum, and S lugdunensis were identified. 37 CoNS were penicillin resistant, 12 gentamicin resistant, 28 tetracycline resistant, 18 erythromycin resistant, four ciprofloxacin resistant, and one teicoplanin resistant (MIC, 32 microg/ml). In total, 16 strains were resistant to three or more antibiotics. CONCLUSION: Species of CoNS apart from S epidermidis may be isolated from patients with corneal and external infection. Antibiotic susceptibility of CoNS is unpredictable and multiresistant strains are common. As a result, antibiotic susceptibility testing should be performed in all cases of clinically significant ocular infections caused by CoNS.

Anti-Bacterial Agents↗
PubMed1999

Identification of HIV patients with active pulmonary tuberculosis using urine based polymerase chain reaction assay.

BACKGROUND: Despite the increased dissemination of tuberculosis among HIV infected patients, the diagnosis is difficult to establish. Traditional microbiological methods lack satisfactory sensitivity. We have developed a highly sensitive and specific nested polymerase chain reaction (PCR) capable of detecting Mycobacterium tuberculosis DNA in urine specimens and have used this test to examine urine specimens from HIV patients with active pulmonary tuberculosis. METHODS: Urine specimens from 13 HIV infected patients with microbiologically proven active pulmonary tuberculosis, 10 AIDS patients with non-tuberculous mycobacterial infection (documented by blood culture), 53 AIDS patients with no evidence of mycobacterial disease, and 80 healthy subjects (25 with positive skin test to purified protein derivative) were tested for M tuberculosis using PCR, acid fast staining (AFS), and culture. RESULTS: Of the urine specimens from patients with active tuberculosis, all tested positive by PCR, two by culture, and none by AFS. No reactivity was observed in urine specimens from patients with non-tuberculous mycobacterial infection. Of the 53 AIDS patients without mycobacterial infection, one had a positive urine PCR. Normal subjects were all negative. CONCLUSIONS: Urine based nested PCR for M tuberculosis may be a useful test for identifying HIV patients with pulmonary tuberculosis.

AIDS-Related Opportunistic Infections↗
PubMed1999

Molecular typing of Candida spp. by random amplification of polymorphic DNA and analysis of restriction fragment length polymorphism of ribosomal DNA repeats.

Random amplification of polymorphic DNA (RAPD) using an arbitrary oligonucleotide primer (5'-CGGTGCGACG) and analysis of restriction fragment length polymorphism of ribosomal DNA (rDNA-RFLP) after digestion of genomic DNA with restriction endonuclease EcoRI were investigated as tools for genotypic delineation beyond the species level of 91 Candida clinical isolates and four reference strains including 33 Candida albicans, 19 Candida tropicalis, 22 Candida krusei and 21 Candida (Torulopsis) glabrata. Results indicated that both techniques can be useful for typing isolates of the above species, although showing a variable discriminative potential with different species. As compared to RAPD fingerprinting, the discriminative potential of rDNA-RFLP appeared to be highest for C. albicans and lowest for C. glabrata, being overall similar for C. krusei and identical for C. tropicalis. A comparative analysis of the results obtained with the two typing techniques showed that, except for C. tropicalis, they were able to provide non-redundant information, and that their use in combination could enhance the discriminative potential for delineation among C. glabrata and C. krusei isolates.

Candida↗
PubMed1999

[Foix-Chavany-Marie syndrome in a child caused by a head trauma].

We report the case of a traumatic Foix-Chavany-Marie syndrome (SFMC) which is the cortico-subcortical type of suprabulbar palsy. A 10-year-old boy was brain injured in a traffic accident in August 1996. He was found comatous (initial GCS = 6) without any focal neurological deficit. The hemodynamic situation was stable even though he presented two wounds of the scalp and a hemoperitoneum that required intensive perfusions. The initial CT scan elicited a frontal fracture, ischemo hemorrhagic lesions of the right frontopolar and anterior temporal cortex. On the second day, he developed on the left side a subdural collection and a extradural hematoma which was surgically withdrawn. The comatous state ended on the ninth day. On examination, The child was awake and alert, able to understand spoken and written language but unable to speak. There was masticatory diplegia: the mouth was half open, the patient was drooling, chewing was impossible. The most striking feature was the automatic voluntary dissociation which might be observed on laughing, crying and yawning. The patient was unable to initiate swallowing but reflex swallowing was preserved once food was placed into the pharynx. The child had a deficit of voluntary control of muscles supplied by nerves V, VI, IX, X, XI. These clinical features are the hallmarks of SFMC. The first case was reported in 1837 by Magnus. The syndrome was described by Foix Chavany et Marie in 1926, and called SFMC by Weller (1993). His literature review of 62 SFMC allowed the differentiation of five clinical types: the classical and most common form associated with cerebrovascular disease, a subacute form caused by central nervous system infections, a developmental form, a reversible form in children with epilepsy and a rare type associated with neurodegenerative disorders. Bilateral opercular lesions was confirmed in 31 of 41 patients who had CT or MRI performed, and by necropsy in 7 of 10 patients. As previously reported, the outcome was poor for this boy who recovered very limited orofacial motor abilities. The medical functional readaptation was long et tedious and took in consideration the fact that the speech disturbance was anarthria and not an aphasic or an apraxic one and the age of onset of this acute acquired syndrome.

Acute Disease↗
PubMed1999

Molecular characterization of Streptococcus equi subspecies equi isolated from an Ethiopian camel by ribotyping and PCR-ribotyping.

The aim of this study was to characterize a S. equi subspecies equi strain isolated from an Ethiopian camel by different molecular techniques (Ribotyping and PCR-Ribotyping). We compared the results obtained with those generated from two strains of the Pasteur Collection. The ribotyping showed the highest power of differentiation, distinguishing between the strains analyzed, whereas PCR-Ribotyping was able only to differentiate the camel isolate but not the strains from the Pasteur Collection. The application of this technique will be very useful to establish a clonal relationship among equine and camelids strains and help the prevention and cure of the equine and camel pathology.

Animals↗
PubMed1999

Humoral immune responses to multiple antigens of Mycobacterium tuberculosis in tuberculosis patients co-infected with the human immunodeficiency virus.

A panel of ten protein antigens of Mycobacterium tuberculosis was used to evaluate serum antibody responses to tuberculosis in patients co-infected with the human immunodeficiency virus (HIV) and in HIV-infected control individuals without tuberculosis. Most (70%) of the tuberculosis patients had serum reactivity to at least one antigen and maintained the diverse antibody repertoire previously observed in HIV-negative tuberculosis patients.

Antibody Formation↗