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C Piersimoni

Publications and source records attributed to C Piersimoni.

At least 37 records · Page 2Linked to original sources
PubMed1997

Characterization of mycobacterial isolates phylogenetically related to, but different from Mycobacterium simiae.

The use of high-performance liquid chromatography (HPLC) revealed four previously unreported profiles within a group of mycobacteria consisting of 14 clinical isolates. These mycobacteria, whose identification by conventional tests appeared problematic, mostly resembled Mycobacterium avium complex or Mycobacterium simiae. Genetic analysis revealed, within this group, six different nucleic acid sequences in a hypervariable 16S rRNA segment, but all the isolates appeared to be phylogenetically related to M. simiae. Six isolates representing the largest of groups defined by means of genetic sequencing turned out to belong to the newly described species Mycobacterium lentiflavum. Furthermore, three such clusters precisely coincided with three of those defined by HPLC, while the three remaining clusters shared almost identical HPLC profiles. All but one strain (which, although clearly not belonging to the M. avium complex, hybridized with specific commercial DNA probes) showed high-grade resistance to the majority of antimycobacterial drugs. Three of the isolates were clinically significant according to stringent criteria. Sophisticated techniques, like genetic sequencing or HPLC, by now seem indispensable for differentiating unusual and new mycobacteria from well-established ones.

Adult↗
PubMed1996

Detection of a vacuolating cytotoxin in stools from children with diarrhea.

A cytotoxin inducing vacuolation in HEp-2 cells was detected in 19 (3.1%) of 618 stool specimens from children with diarrhea but in none of 135 from control children. Common enteric pathogens were found in only two (10.5%) of the 19 cytotoxin-positive stool specimens. The vacuoles induced by stool filtrates resembled those induced by the vacuolating toxin (VacA) of Helicobacter pylori. The vacuolating toxin was heat-labile and protease-sensitive, and it had an apparent molecular weight of > 100,000 but was not neutralized by an antiserum to H. pylori VacA. Although proper prospective case-control studies are needed to definitely assess the etiologic association between the new vacuolating cytotoxin and diarrhea, the present study suggests that microorganisms of the gastrointestinal tract produce a Helicobacter-like vacuolating toxin and may be responsible for cases of childhood diarrhea whose etiology is currently considered unknown.

Bacterial Proteins↗
PubMed1996

Enteropathogens associated with childhood diarrhea in Italy. The Italian Study Group on Gastrointestinal Infections.

BACKGROUND: Infectious diarrheal diseases remain an important cause of childhood morbidity in industrialized countries. The knowledge of the etiology and epidemiology of childhood diarrhea in a given area is needed to plan any measure designed to prevent or ameliorate diarrheal illness and to develop practice guidelines for the most appropriate stool examination procedures. METHODS: We evaluated 618 children with diarrhea and 135 controls prospectively for viral, bacterial and parasitic enteric pathogens. Diarrheagenic Escherichia coli was identified by gene probes specific to different virulence factors. Stool filtrates were examined for the presence of free bacterial toxins by a cell culture cytotoxicity assay. Clinical and epidemiologic data were recorded and analyzed in relation to microbiologic findings. RESULTS: Enteropathogens were identified in 59% of children with diarrhea and in 10.4% of asymptomatic controls. The agents mainly associated with disease were rotavirus (23.6%), Salmonella (19.2%) and Campylobacter (7.9%). Rotavirus was significantly more frequent among children observed as inpatients whereas Campylobacter was significantly more common in outpatients. Infections with diarrheagenic E. coli, Shigella flexneri, yersinia enterocolitica, Cryptosporidium and Giardia were observed in a limited number of patients. The clinical presentation of children was not sufficiently characteristic to permit presumptive diagnosis of a specific pathogen. conversely the presence of blood and/or leukocytes in stools had a high positive predictive value for Salmonella or Campylobacter infection. CONCLUSION: The results of this study will be useful for planning strategies to prevent and control diarrheal diseases in our country.

Child↗
PubMed1996

Type frequency and antimicrobial susceptibility of Mycobacterium avium-intracellulare complex strains isolated in Italy from AIDS and non-AIDS patients.

Typing of the glycopeptidolipid antigens performed by thin layer chromatography on 59 Mycobacterium avium-intracellulare (MAC) strains isolated in Italy from AIDS patients showed that the most frequent types were 1, 4, 3, 8, and 21 (24, 19, 14, 14 and 8% of the strains, respectively). Among non-AIDS patients, types 1, 4 and 8 were also frequently found. The antimicrobial susceptibility tested in agar and/or liquid media to a panel of drugs indicated in clofazimine and rifabutin effective agents against both AIDS and non-AIDS strains. The data obtained show that MAC type distribution in Italy appears to be different from that reported for other countries. No major differences in drug susceptibility between AIDS and non-AIDS related strains were found.

AIDS-Related Opportunistic Infections↗
PubMed1995

Comparison of two selective media and a membrane filter technique for isolation of Campylobacter species from diarrhoeal stools.

Diarrhoeal stool specimens from 415 patients were examined for Campylobacter spp. by culture on charcoal cefoperazone deoxycholate agar (CCDA), Skirrow medium and Columbia blood agar overlaid with a 0.65 micron pore size membrane filter. Forty-eight Campylobacter strains were isolated from 45 (10.8%) specimens by all media; 44 were Campylobacter jejuni (91.7%), three were Campylobacter coli (6.3%) and one was Campylobacter hyointestinalis (2.0%). The percentages of Campylobacter-positive specimens isolated on Skirrow medium, CCDA and the membrane filter were 62, 82 and 95%, respectively. The recovery of more Campylobacter spp. from the same stool sample was achieved by the membrane filter method only. The highest isolation rate (100%) was observed when culture on CCDA and the membrane filter method were combined.

Bacteriological Techniques↗
PubMed1995

Mycobacterium malmoense in Italy.

A case of mycobacterial lymphadenitis due to Mycobacterium malmoense was recently diagnosed in a 5-year-old girl. The organism was isolated from pus and tissue fragments obtained by surgical excision of the affected nodes. This is the first documented case of human infection due to this organism in Italy.

Child, Preschool↗
PubMed1995

Activity of seven antimicrobial agents, alone and in combination, against AIDS-associated isolates of Mycobacterium avium complex.

The activity of seven antimicrobial agents (and five two-drug combinations and five three-drug combinations) was investigated against 37 clinical isolates of Mycobacterium avium recovered from blood cultures of AIDS patients. The susceptibility tests were performed in Middlebrook 7H12 broth using a radiometric method. MICs of amikacin, ciprofloxacin, clarithromycin, clofazimine, ethambutol, rifabutin and sparfloxacin were determined. Five antimicrobial agents were tested in combination with clarithromycin and also with clarithromycin plus amikacin to look for possible synergic activity. Synergic activity in combination with clarithromycin and with clarithromycin plus amikacin, was detected for rifabutin (54% and 51% of isolates, respectively), clofazimine (38% and 35%), ethambutol (16% and 32%), ciprofloxacin (8% and 14%) and sparfloxacin (3% and 8%). No antagonism was observed. We conclude that clarithromycin is an essential component in the chemotherapy of M. avium complex disease.

AIDS-Related Opportunistic Infections↗
PubMed1995

In vitro and ex vivo activities of antimicrobial agents used in combination with clarithromycin, with or without amikacin, against Mycobacterium avium.

MICs of clarithromycin, amikacin, isoniazid, rifabutin, ciprofloxacin, sparfloxacin, ethambutol, and clofazimine were determined for six isolates of Mycobacterium avium complex (MAC) from AIDS patients both by the radiometric method and by an ex vivo model of infection in human macrophages. The median MICs in macrophages were similar or slightly lower than values found in broth, except for amikacin, which had slightly higher MICs inside the cells. Combinations of clarithromycin with other antimicrobial agents showed that clarithromycin-clofazimine and clarithromycin-rifabutin were synergistic on five of six strains while clarithromycin-amikacin and clarithromycin-isoniazid were antagonistic on one and two strains, respectively. The addition of amikacin made the combinations of clarithromycin-clofazimine and clarithromycin-ethambutol synergistic against all the MAC strains. In the macrophage model, the combination of clarithromycin-clofazimine (mean survival, 21%) and clarithromycin-rifabutin (mean survival, 29%) showed a strong reduction in viable counts compared with single drugs, while clarithromycin-amikacin was less active than single drugs alone. In general, the addition of amikacin did not improve the activity of the combinations, except for clarithromycin-isoniazid-amikacin (mean survival, 19%), which was significantly more active than either clarithromycin-isoniazid or clarithromycin-amikacin. The use of the macrophage model can suggest new combinations of antimicrobial agents with anti-MAC activity which, on the basis of their in vitro effectiveness, would probably be disregarded for assay in animal models.

Amikacin↗
PubMed1995

Isolation of the newly described species Mycobacterium celatum from AIDS patients.

Mycobacterium celatum is a recently described species which, on the basis of conventional tests, may be misidentified as Mycobacterium xenopi or as belonging to the Mycobacterium avium complex. Only genomic sequencing or high-performance liquid chromatography of cell wall mycolic acids can presently allow a correct identification of this mycobacterium. Two cases of infection due to M. celatum, in AIDS patients, are described here. The quantitative susceptibility pattern of the isolates to a wide spectrum of drugs is also reported.

AIDS-Related Opportunistic Infections↗
PubMed1994

Evaluation of a commercial DNA probe assay for the identification of Mycobacterium kansasii.

A commercially available DNA probe (the AccuProbe Mycobacterium kansasii culture identification test, Gen-Probe, USA) for the identification of Mycobacterium kansasii was tested on a panel of 143 fully characterized mycobacterial strains. The isolates included 70 Mycobacterium kansasii and 73 mycobacteria other than kansasii. The specificity was 100% while the sensitivity was 72.8%. This sensitivity is unusually low in comparison with that of commercial DNA probes for other mycobacteria and confirms a previous study that found genetic heterogeneity within the species Mycobacterium kansasii. Strains that do not hybridize with the AccuProbe are particularly prevalent in Italy and perhaps elsewhere in Europe.

DNA Probes↗
PubMed1994

Bacteriostatic and bactericidal activities of paromomycin against Mycobacterium avium complex isolates.

The MICs and MBCs of paromomycin for 32 Mycobacterium avium complex (MAC) strains isolated from patients with the acquired immunodeficiency syndrome were determined by a radiometric broth dilution method. The MICs for the majority of strains were either 8 or 16 mg/L and the MBCs were four- to eight-fold higher. Paromomycin merits further evaluation as oral prophylaxis against disseminated MAC infection.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Characterization of mesophilic Aeromonas from clinical specimens by computerized analysis of SDS-PAGE protein profiles and by enzymatic activity.

Mesophilic Aeromonas (Aeromonas hydrophila, Aeromonas sobria, Aeromonas caviae) have recently been considered important aetiological agents of human diseases, mainly gastrointestinal infections. Although several findings have pointed out the significance of this group of microorganisms as enteric pathogens and suggested the presence of virulence factors, epidemiological and clinical studies are limited by the difficulty of correctly identifying mesophilic Aeromonas at the species level. SDS-PAGE of radiolabelled total protein profiles and bacterial enzymatic activities were used to type 31 clinical isolates (6 A. hydrophila, 7 A. sobria and 18 A. caviae) from patients with gastroenteritis and from healthy controls. Analysis of SDS-PAGE protein patterns, reinforced by the UPGMA-grouping system (AMBIS software) provided a good characterization of A. caviae strains as a homogeneous group of microorganisms, possessing significant differences from the other two species of mesophilic Aeromonas, in good agreement with biochemical and enzymatic tests. Data obtained in analyzing A. sobria protein profiles clearly showed two groups, with a correlation coefficient (CC) = 0.70, which in our experience is a doubtful value for assigning two strains to the same species. Strains biochemically identified as A. hydrophila showed a CC = 0.64, which is equally not acceptable for species assignment. Inter-species comparison highlighted this heterogeneity, showing two mixed subgroups, both containing strains that were assigned to A. sobria and A. hydrophila species on the basis of biochemical features.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Comparative evaluation of the MB-Check system for recovery of mycobacteria from clinical specimens.

The performance of the MB-Check system (Roche) in the recovery of mycobacteria from clinical specimens was compared with that of the Bactec radiometric system and conventional culture on Löwenstein-Jensen medium. A total of 1,582 clinical specimens were used for the study; 74 yielded mycobacteria. Organisms of the Mycobacterium tuberculosis and Mycobacterium avium complexes accounted for the majority of isolates. The rate of recovery of all mycobacteria with the Bactec system was 91.9%, with the MB-Check system 79.7% and on Löwenstein-Jensen medium only 54.1%. Combination of the Bactec and MB-Check systems allowed recovery of 100% of isolates. The Bactec system showed a faster detection time than the other two methods.

Bacteriological Techniques↗
PubMed1992

Nonmycetomic Actinomadura madurae infection in a patient with AIDS.

Actinomadura madurae is an aerobic actinomycete which is best known worldwide as the cause of actinomycotic mycetomas. It has not previously been reported to have caused invasive pulmonary or disseminated infection in humans. We describe an AIDS patient with opportunistic A. madurae-induced pneumonia and bacteremia. The isolate from the patient's blood was subjected to dilutional antimicrobial susceptibility tests with 12 antimicrobial agents and was found to have a wide spectrum of susceptibility. This unusual microorganism may be a cause of infections in severely immunosuppressed patients.

Acquired Immunodeficiency Syndrome↗
PubMed1992

In vitro activity of the new quinolone lomefloxacin against Mycobacterium tuberculosis.

Minimal inhibitory concentrations (MIC) of ciprofloxacin, ofloxacin and lomefloxacin were determined for 90 Mycobacterium tuberculosis strains isolated from both AIDS and other patients. Eleven (12.2%) of these strains showed in vitro resistance to one or more first-line antituberculosis drugs. Susceptibility tests were done in 7H12 broth by the radiometric method. The MIC range for ciprofloxacin was 0.125 to 4.0 micrograms/ml; for ofloxacin, 0.25 to 4.0; and for lomefloxacin 0.5 to 4.0 micrograms/ml. On the basis of our data, we believe that the following MIC, when determined in 7H12 broth radiometrically, should be used as break points to classify the strain as susceptible: ciprofloxacin and ofloxacin, 1 microgram/ml or less; lomefloxacin, 2 micrograms/ml or less. Lomefloxacin on a once-daily basis deserves further evaluation as a potential supplementary drug for the treatment of tuberculosis.

Anti-Infective Agents↗