Biomedical subjects

F Barchiesi

Publications and source records attributed to F Barchiesi.

At least 55 records · Page 3Linked to original sources

PubMed1999

Electrophoretic karyotyping and triazole susceptibility of Candida glabrata clinical isolates.

A series of 35 strains of Candida glabrata isolated from 29 subjects (5 AIDS patients and 24 HIV-seronegative individuals) were typed by electrophoretic karyotyping and tested for their susceptibilities to both fluconazole and itraconazole. Almost every individual harboured his/her own specific isolate (DNA type). Neither the source of isolation nor the patient's HIV status was associated with a given DNA type. Recurrences were generally due to the persistence of the same DNA type over time. Only 9% of the isolates showed reduced susceptibility to fluconazole (MIC > or = 8.0 microg/ml), while 43% of the isolates showed reduced susceptibility to itraconazole (MIC > or = 0.25 microg/ml) (P = 0.02). These data show that electrophoretic karyotyping is a useful technique for DNA typing of isolates of Candida glabrata. Care must be taken prior to initiation of antifungal therapy with either of these drugs.

Antifungal Agents↗

PubMed1999

In vitro anticryptosporidial activity of ranalexin alone and in combination with other peptides and with hydrophobic antibiotics.

The in vitro activity of ranalexin alone and in combination with other cationic peptides, macrolides, rifampin, and rifabutin was investigated against a clinical isolate of Cryptosporidium parvum. Susceptibility tests were performed by inoculation of the isolate onto cell monolayers and determining the parasite count after 48 h of incubation at 37 degrees C. Antibiotic-free cultures were used as controls in the study. Ranalexin showed low anticryptosporidial activity: it suppressed the growth of parasites by > or = 40% at 50 microM. Ranalexin showed enhanced activity when it was combined with noninhibitory concentrations of other compounds: a 74.4-94.1% reduction in the number of parasites was observed when ranalexin 50 microM was combined with magainin II 50 microM, indolicidin 50 microM, clarithromycin 8 mg/l, azithromycin 8 mg/l, rifampin 8 mg/l, and rifabutin 8 mg/l. The results suggest that ranalexin may be effective in inhibiting Cryptosporidium parvum growth in vitro upon combination with other peptides and hydrophobic antibiotics.

Animals↗

PubMed1999

Efficacy of treatment with paromomycin, azithromycin, and nitazoxanide in a patient with disseminated cryptosporidiosis.

A 24-year-old HIV-positive heterosexual woman with disseminated cryptosporidiosis was monitored from January 1998 to May 1999. During this period, consecutive stool, sputum, and bile examinations showed the constant presence of Cryptosporidium oocysts. Although the patient was repeatedly treated with oral paromomycin and azithromycin and, finally, nitazoxanide, her condition continued to deteriorate. In order to monitor the in vitro susceptibility of the parasite, specimens from various sites were collected periodically. When the first clinical isolate was tested, the antimicrobial agents used (azithromycin at a concentration of 8 mg/l, paromomycin at of 1 mg/ml, and nitazoxanide at 10 mg/l) produced a decrease in parasite counts of 26.5%, 63.4%, and 67.2%, respectively. Subsequent isolates of Cryptosporidium parvum showed similar susceptibilities. This case demonstrates that failure of clinical treatment corresponded to inadequate growth inhibition of the parasite in vitro.

AIDS-Related Opportunistic Infections↗

PubMed1999

Infection due to Absidia corymbifera in a patient with a massive crush trauma of the foot.

We report the case of a patient with a massive crushing trauma of the right foot who developed a local infection due to Absidia corymbifera. Systemic and local antifungal therapy with ketoconazole associated with hyperbaric oxygen therapy (HBO) yielded a rapid clinical and microbiological resolution. Controlled clinical studies are warranted to further elucidate the potential utility of HBO/antifungal combination therapy.

Absidia↗

PubMed1999

Antimicrobial activity of polycationic peptides.

The in vitro activity of six polycationic peptides, buforin II, cecropin P1, indolicidin, magainin II, nisin, and ranalexin, were evaluated against several clinical isolates of gram-positive and gram-negative aerobic bacteria, yeasts, Pneumocystis carinii and Cryptosporidium parvum, by using microbroth dilution methods. The peptides exhibited different antibacterial activities and rapid time-dependent killing. The gram-negative organisms were more susceptible to buforin II and cecropin P1, whereas buforin II and ranalexin were the most active compounds against the gram-positive strains. Similarly, ranalexin showed the highest activity against Candida spp., whereas magainin II exerted the highest anticryptococcal activity. Finally, the peptides showed high anti-Pneumocystis activity, whereas no compound had strong inhibitory effect on C. parvum.

Amino Acid Sequence↗

PubMed1999

In-vitro activity of five antifungal agents against uncommon clinical isolates of Candida spp.

A broth microdilution method and an agar dilution method were used for testing fluconazole, itraconazole, ketoconazole, flucytosine and amphotericin B against 98 clinical isolates belonging to seven species of Candida. The approximate rank order of fluconazole MICs was Candida lusitaniae approximately Candida kefyr < Candida famata approximately Candida guilliermondii < Candida pelliculosa approximately C. lipolytica approximately Candida inconspicua. Candida lypolitica and C. pelliculosa were the species least susceptible to itraconazole and ketoconazole. Flucytosine MICs revealed the highest prevalence of resistant strains among C. lipolytica and C. lusitaniae. All isolates were susceptible to amphotericin B.

Amphotericin B↗

PubMed1999

In-vitro interactions of itraconazole with flucytosine against clinical isolates of Cryptococcus neoformans.

Treatment failures can occur in AIDS patients infected with Cryptococcus neoformans, despite aggressive antifungal therapy. Combination regimens with additive or synergic drugs could provide additional options for treating cryptococcosis. We studied the effects of itraconazole combined with flucytosine against 16 strains of C. neoformans var. neoformans. Combination therapy revealed different results for the various strains, including synergy (fractional inhibitory concentration (FIC) index 0.5, 63% of the interactions), addition (FIC >0.5 to 1.0, 31% of the interactions) and indifference (FIC >1.0 to <2.0, 6% of the interactions). Antagonism (FIC >2.0) was not observed. The efficacy of combination therapy was confirmed by quantitative cfu and killing curve assays. In particular, killing curves conducted in replicating cells showed that the addition of itraconazole prevented the development of flucytosine-resistant mutants of C. neoformans. These data show that the combination of itraconazole and flucytosine is significantly more active than either drug alone against C. neoformans in vitro.

Antifungal Agents↗

PubMed1999

In-vitro activity of dicationic aromatic compounds and fluconazole against Cryptococcus neoformans and Candida spp.

We investigated the in-vitro activity of three selected dicationic aromatic compounds for nine clinical isolates of Cryptococcus neoformans and 93 clinical isolates of Candida spp., representing 12 different species, using a broth macrodilution method following NCCLS recommendations. All the clinical isolates were also tested for fluconazole susceptibility. The in-vitro data demonstrate that compounds 39 and 57 have excellent in-vitro activity for all tested strains (MIC 0.19-1.56 mg/L) except Candida pelliculosa. Moreover, compound 39 showed excellent in-vitro fungicidal activity against Candida krusei, Candida glabrata, Candida lusitaniae and Cryptococcus neoformans with MFCs in the range 0.39-6.25 mg/L. Both compounds 39 and 57 showed excellent in-vitro activity against fluconazole-resistant Candida albicans isolates, including a C. albicans strain that contains all known fluconazole-resistant mechanisms. Comparing MIC data from compounds 21, 39 and 57 with fluconazole, we found a statistically significant difference only with compound 39 (P = 0.043). However, comparing MFC data from compounds 21, 39 and 57 with fluconazole, we found statistically significant differences with all three compounds (P < 0.00001). These data indicate the potential antifungal breadth of two bis-benzimidazoles (compounds 39 and 57) as antifungal agents against yeasts. If it can be determined that compounds 39 and 57 are effective and non-toxic in vivo, the prospect of these compounds as clinically useful antifungal agents will be enhanced.

Antifungal Agents↗

PubMed1999

In-vitro activity of polycationic peptides against Cryptosporidium parvum, Pneumocystis carinii and yeast clinical isolates.

The in-vitro activity of magainin II, indolicidin and ranalexin against 14 clinical isolates of eukaryotic microorganisms was evaluated. Antifungal susceptibility testing was performed by broth microdilution, and activity against Pneumocystis carinii and Cryptosporidium parvum was determined by inoculation on to cell monolayers. For yeasts, peptide MICs and MFCs ranged from 6.25 to > 50 mg/L. Ranalexin showed the highest activity against Candida spp., while magainin II demonstrated greatest anticryptococcal activity. The peptides suppressed the growth of P. carinii by > or = 50% and > or = 90% at 5 and 50 microM, respectively, with the exception of indolicidin. Ranalexin, the most effective compound against C. parvum, suppressed its growth by > or = 40% at 50 microM.

Animals↗

PubMed1999

In-vitro activity of cationic peptides alone and in combination with clinically used antimicrobial agents against Pseudomonas aeruginosa.

The in-vitro activity of cecropin P1, indolicidin, magainin II, nisin and ranalexin alone and in combination with nine clinically used antimicrobial agents was investigated against a control strain, Pseudomonas aeruginosa ATCC 27853 and 40 clinical isolates of P. aeruginosa. Antimicrobial activities were measured by MIC, MBC and viable count. In the combination study, the clinically used antibiotics were used at concentrations close to their mean serum level in humans in order to establish the clinical relevance of the results. To select peptide-resistant mutants, P. aeruginosa ATCC 27853 was treated with consecutive cycles of exposure to each peptide at 1 x MIC. The peptides had a varied range of inhibitory values: all isolates were more susceptible to cecropin P1, while ranalexin showed the lowest activity. Nevertheless, synergy was observed when the peptides were combined with polymyxin E and clarithromycin. Consecutive exposures to each peptide at 1 x MIC resulted in the selection of stable resistant mutants. Cationic peptides might be valuable as new antimicrobial agents. Our findings show that they are effective against P. aeruginosa, and that their activity is enhanced when they are combined with clinically used antimicrobial agents, particularly with polymyxin E and clarithromycin.

Anti-Bacterial Agents↗

PubMed1999

In-vitro activity of rifabutin and albendazole singly and in combination with other clinically used antimicrobial agents against Pneumocystis carinii.

The in-vitro activity of rifabutin and albendazole alone and in combination with clarithromycin, etoposide, minocycline and pyrimethamine was investigated against four clinical isolates of Pneumocystis carinii. The susceptibility tests were performed by inoculation of the isolates on to cell monolayers and by determining the parasite count after 72 h incubation at 37 degrees C. The culture medium was supplemented with serial dilutions of each agent. Albendazole tested alone was more active than rifabutin. Albendazole suppressed the growth of cysts and trophozoites by >50% at 4 mg/L. Rifabutin, at the same concentration, produced about 40% reduction in the mean cyst and trophozoite counts. Albendazole (4 mg/L) combined with etoposide 4 mg/L showed the highest anti-P. carinii activity, with a decrease of 86.3% and 90.1% in cyst and trophozoite counts, respectively. The greatest synergic interaction was detected when rifabutin (4 mg/L) was combined with clarithromycin (4 mg/L). Our study suggests that clinically used antimicrobial agents may be effective in inhibiting P. carinii growth in vitro and that, above all, some of these agents possess a positive interaction upon combination with other clinically used compounds. These findings may be useful in the establishment of a prophylaxis regimen for multiple opportunistic pathogens.

Albendazole↗

PubMed1998

In vitro activity of five antifungal agents against clinical isolates of Saccharomyces cerevisiae.

We evaluated the in vitro activity of fluconazole, itraconazole, ketoconazole, 5-fluorocytosine and amphotericin B against 30 clinical isolates of Saccharomyces cerevisiae by a broth microdilution method, following the NCCLS recommendation. Testing was performed either in RPMI-1640 or yeast nitrogen base (YNB). YNB supported the growth of all isolates tested, while results in RPMI-1640 were not obtained for six isolates (20%). The MIC of all three azoles in YNB were one or two dilutions higher than those obtained in RPMI-1640 (P=0.0001 for fluconazole and itraconazole, P=0.03 for ketoconazole). Elevated MICs were observed for all three azoles, while all the isolates were susceptible to 5-fluorocytosine and amphotericin B. All MIC values were confirmed by spectrophotometric reading. Six strains of S. cerevisiae isolated from the faeces and consecutive blood cultures from an AIDS patient over a 7-month period were typed by electrophoretic karyotyping (EK). EK showed the maintenance of the same karyotype over time suggesting that the faecal isolate changed from a colonizing to infection-causing strain. The relative resistance of S. cerevisiae to azole drugs as well as its ability to cause widespread infections may promote the emergence of this species as a pathogen in immunosuppressed patients.

AIDS-Related Opportunistic Infections↗

PubMed1998

In-vitro interaction of terbinafine with amphotericin B, fluconazole and itraconazole against clinical isolates of Candida albicans.

A chequerboard titration broth microdilution method, performed according to the recommendations of the National Committee for Clinical Laboratory Standards, was applied to study the in-vitro interaction of terbinafine with amphotericin B, fluconazole and itraconazole against 30 strains of Candida albicans isolated from the oral cavities of AIDS patients. MICs were determined spectrophotometrically at 490 nm and read at either 24 h or 48 h. The end-point was defined as the drug concentration resulting in > or = 90% inhibition of growth relative to control growth. Synergy, defined as a fractional inhibitory concentration (FIC) index of < or = 0.50, was observed in 93% (28 of 30) of terbinafine-amphotericin B interactions, in 47% (14 of 30) of terbinafine-fluconazole interactions and in 43% (13 of 30) of terbinafine-itraconazole interactions; antagonism (FIC > 2.0) was not observed. Where synergy was not achieved, there was still a decrease, although not as dramatic, in the MIC of one or both drugs when used in combination. Reading the MICs on day 2 did not significantly affect the mode of interaction of terbinafine-triazoles, while for terbinafine-amphotericin B the proportion of synergic interactions dropped from 93% (28 of 30) to 30% (nine of 30; P = 0.0001). Antagonism was not observed for any drug combination even at 48 h. Minimum fungicidal concentrations (MFCs) of all drugs alone and in combination were determined against five isolates. Neither terbinafine nor the two triazoles showed fungicidal activity when tested alone or in combination. The fungicidal activity of amphotericin B was slightly enhanced when combined with terbinafine, there being a decrease of two-fold dilutions in the amphotericin B MFCs against all five isolates tested. Thus terbinafine enhances the activities of amphotericin B and triazoles against C. albicans in vitro. Clearly, clinical studies are warranted to elucidate further the potential utility of these combination therapies.

Amphotericin B↗

PubMed1998

Fluconazole susceptibility and strain variation of Candida albicans isolates from HIV-infected patients with oropharyngeal candidosis.

Over a 16 month period we conducted a prospective study in a cohort of 45 HIV-positive patients to detect the development of resistance to fluconazole and to analyse the epidemiology of oropharyngeal candidosis (OPC). Each episode was treated with fluconazole 100 mg/day po for 10 days. All yeast isolates were tested for their in-vitro susceptibility to fluconazole. Multiple strains of Candida albicans simultaneously isolated from a given patient were typed by electrophoretic karyotyping. Overall, 106 episodes of OPC were diagnosed among the 45 patients: 18/45 patients (40%) had only one episode, 11/45 (24%) had two episodes, and the remaining 16/45 (36%) had three or more episodes (range 3-7). Cure (complete resolution of signs and symptoms and negative post-treatment cultures) and improvement (complete resolution of signs and symptoms but positive post-treatment cultures) were observed in 30/106 (28%) and 69/106 (65%) episodes of OPC, respectively. Failure (absence of improvement or exacerbation of signs and symptoms) was observed in seven episodes (7%) from four patients. In two of these four patients a significant and progressive increase in fluconazole MICs was observed: from 0.25 to 16 mg/L in one patient, and from < or = 0.125 to 32 mg/L in the second one. Tests on multiple colonies from individual isolation plates showed that it was not unusual to obtain different fluconazole MICs, indicating that, in order to avoid misleading results, one should perform in-vitro susceptibility testing by using a multiple colony inoculum rather than an inoculum made from a single colony. A total of 213 strains of C. albicans isolated from seven patients who suffered from four or more episodes of OPC through the course of the study were typed by electrophoretic karyotyping. Five individuals (71%) were infected with yeasts with only one DNA type, while the other two patients showed the presence of two or three different DNA types. The simultaneous presence of multiple types was found only in one of the seven subjects. Our data confirm the efficacy of fluconazole 100 mg/day for the treatment of OPC in HIV patients. Isolation of fluconazole-resistant strains of C. albicans with this regimen is rare. The vast majority of HIV patients are infected with a unique strain of C. albicans throughout each episode of infection. A minority of patients, however, can harbour strains of C. albicans with variable patterns of fluconazole susceptibility simultaneously.

AIDS-Related Opportunistic Infections↗

PubMed1998

In-vitro activity of lytic peptides, inhibitors of ion transport systems and ionophorous antibiotics against Pneumocystis carinii.

The in-vitro activity of two vertebrate lytic peptides, two ion transport system inhibitors and two polyether ionophores was investigated against four clinical isolates of Pneumocystis carinii recovered from bronchoalveolar lavages of AIDS patients. The susceptibility tests were performed by inoculating the isolates on to cell monolayers and determining the parasite count after 72 h incubation at 37 degrees C. The culture medium was supplemented with Dulbecco's modified Eagle's medium containing serial dilutions of cecropin P1, magainin II, benzamil, 5-(Nmethyl-Nisobutyl)amiloride (MIBA), lasalocid and nigericin. The two vertebrate lytic peptides showed high activity against trophozoites and cysts. At a concentration of 66.77 mg/L, cecropin P1 produced a 93.3% and 98.1% reduction in cyst and trophozoite counts, respectively, while magainin II at a concentration of 49.33 mg/L produced a 90.6% and 98.7% reduction in cyst and trophozoite counts, respectively. The IC50s of benzamil and MIBA were observed at the highest concentrations tested, 35.62 and 29.98 mg/L, respectively. However, 90% inhibition was not achieved. Lasalocid and nigericin at 0.05 mg/L gave inhibition comparable to that observed with the highest tested concentrations of cecropin P1 and magainin II, but significant injury to the cell monolayer was also observed when nigericin was tested at this concentration. Lasalocid 0.05 mg/L produced a reduction of 91.3% and 92.0% in cyst and trophozoite counts, respectively. Our results suggest that lytic peptides and lasalocid may be effective in inhibiting P. carinii growth at concentrations which are not toxic for the cell monolayer.

AIDS-Related Opportunistic Infections↗

PubMed1998

In-vitro activity of lytic peptides alone and in combination with macrolides and inhibitors of dihydrofolate reductase against Pneumocystis carinii.

The in-vitro activity of cecropin P1, magainin II, indolicidin and ranalexin alone and in combination with macrolides and dihydrofolate reductase inhibitors (DHFRs) was investigated against six clinical isolates of Pneumocystis carinii. The susceptibility tests were performed by inoculation of the isolates on to cell monolayers and determining the parasite count after 72 h incubation at 37 degrees C. The culture medium was supplemented with serial dilutions of each agent. The four peptides suppressed the growth of cysts and trophozoites by > or = 50% at 20 microM and 2 microM, respectively, with the exception of indolicidin (cysts: IC50, 20 microM; trophozoites: IC50, 20 microM). The IC90 values of all peptides for either cysts or trophozoites were observed at a concentration of 20 microM. Our data showed that the activity of lytic peptides remained virtually unchanged when they were tested either alone or in combination with macrolides and DHFRs, with the exception of ranalexin: a cysts/trophozoites reduction in the range 77.3-85.1% was observed when ranalexin 2 microM was combined with 4 mg/L of macrolides. Our study suggests that lytic peptides may be effective in inhibiting the growth of P. carinii in vitro. In addition some of these compounds seem to have an effective interaction with hydrophobic antibiotics.

Anti-Bacterial Agents↗

PubMed1998

Comparison of three methods for testing azole susceptibilities of Candida albicans strains isolated sequentially from oral cavities of AIDS patients.

Three susceptibility testing procedures were compared to determine fluconazole, itraconazole, and ketoconazole MICs against 47 Candida albicans strains isolated sequentially from the oral cavities of five AIDS patients undergoing azole therapy. They included the broth microdilution method (BM), performed according to the National Committee for Clinical Laboratory Standards' tentative standard, the agar dilution method (AD), and the Etest; the latter two tests were performed both in Casitone agar (AD-Cas and Etest-Cas) and in RPMI (AD-RPMI and Etest-RPMI). Twenty-four- and 48-h MICs obtained by AD and Etest were compared with 48-h MICs obtained by BM. The MICs of all the azoles determined by BM were usually lower than those obtained by the other methods, mainly due to different reading criteria. In order to assess the most appropriate way of evaluating the agreement of MICs obtained by different methods with those produced by the proposed reference method (BM), we used the mean differences calculated according to Bland and Altman's method. Comparison of fluconazole MICs obtained by BM and AD-Cas yielded a mean difference of 3, and the percentages of agreement within +/-2 dilutions were 98 and 100% at 24 and 48 h, respectively. For ketoconazole and itraconazole MICs, lower mean differences were noted, and agreement ranged from 96 to 100%. Agreement between the AD-RPMI and BM results was poor for all azoles, and an increase in MICs was always observed between the 1st- and 2nd-day readings. Similarly, Etest-Cas gave better agreement with BM than did Etest-RPMI for all the azoles. BM, AD-Cas, and Etest-Cas each demonstrated a progressive increase in fluconazole MICs against strains isolated sequentially from a given patient, in accordance with the decreased clinical response to fluconazole.

AIDS-Related Opportunistic Infections↗

PubMed1998

In vitro activity of terbinafine against clinical isolates of dermatophytes.

A broth macrodilution method following the recommendations established by the National Committee for Clinical Laboratory Standards was employed for testing terbinafine against 20 clinical isolates of dermatophytes belonging to seven species. The minimal inhibitory concentrations resulting in either 80% or 100% inhibition of growth, compared to growth in drug-free control tubes, ranged from </=0.03 to 0.25 g ml-1 and from </=0.03 to 2.0 g ml-1, respectively. Terbinafine was shown to be fungicidal at a concentration of </=1.0 microg ml-1 for 19 isolates. No differences in susceptibilities were found between strains isolated from HIV-positive and -negative individuals.

Antifungal Agents↗