Direct-acting antivirals in hepatitis C virus (HCV)-infected and HCV/HIV-coinfected patients: real-life safety and efficacy.

OBJECTIVES: Clinical trials of all-oral direct-acting antivirals (DAAs) for chronic hepatitis C virus (HCV) infection reported high response rates in HCV/HIV coinfection, similar to those obtained in HCV monoinfection. We evaluated the safety and efficacy of these regimens in a clinical practice setting. METHODS: In this prospective observational study, all the HCV-monoinfected and HCV/HIV-coinfected patients undergoing HCV treatment with all-oral DAA regimens in a routine clinical setting from December 2014 to December 2015 were included in the analysis. Sustained virological response 12 weeks after the end of therapy (SVR12) and reported adverse events (AEs) were evaluated. Resistance-associated variants (RAVs) were analysed in a subgroup of patients at baseline and at the time of viral rebound in those with virological failure. RESULTS: One-hundred and nine patients (51 HCV-infected and 58 HCV/HIV-coinfected) were enrolled in the study. Sixty per cent had cirrhosis and 52% were pegylated interferon and ribavirin (pegIFN/RBV)-experienced. Thirty-six per cent received ombitasvir + paritaprevir/ritonavir + dasabuvir, 25% sofosbuvir + daclatasvir, 16% sofosbuvir + simeprevir, 17% sofosbuvir + ribavirin and 6% sofosbuvir + ledipasvir; ribavirin was used in 57% of subjects. The SVR12 rate was 91% and 96% in HIV-infected and uninfected patients, respectively (P = 0.44). The 4-week HCV viral decline was similar in the two groups. RAVs were found at baseline in 23 of 49 patients and did not affect SVR12. No predictors of SVR12 were identified in our cohort. CONCLUSIONS: Treatment with all-oral DAA combinations of patients infected with HCV and with HCV/HIV under real-life conditions led to high and similar rates of SVR12. Moreover, the historical factors associated with a sustained virological response to pegIFN/RBV were not predictive of the response to all-oral DAAs.

HCV NS3 sequencing as a reliable and clinically useful tool for the assessment of genotype and resistance mutations for clinical samples with different HCV-RNA levels.

OBJECTIVES: This study aims to evaluate the reliability and clinical utility of NS3 sequencing in hepatitis C virus (HCV) 1-infected patients who were candidates to start a PI-containing regimen. METHODS: NS3 protease sequencing was performed by in-house-developed HCV-1 subtype-specific protocols. Phylogenetic analysis was used to test sequencing reliability and concordance with previous genotype/subtype assignment by commercial genotyping assays. RESULTS: Five hundred and sixty-seven HCV plasma samples with quantifiable HCV-RNA from 326 HCV-infected patients were collected between 2011 and 2014. Overall, the success rate of NS3 sequencing was 88.9%. The success rate between the two subtype protocols (HCV-1a/HCV-1b) was similarly high for samples with HCV-RNA >3 log IU/mL (>92% success rate), while it was slightly lower for HCV-1a samples with HCV-RNA ≤3 log IU/mL compared with HCV-1b samples. Phylogenetic analysis confirmed the genotype/subtype given by commercial genotyping assays in 92.9% (303/326) of cases analysed. In the remaining 23 cases (7.1%), 1 was HCV-1g (previously defined as subtype 1a), 1 was HCV-4d (previously defined as genotype 1b) and 1 was HCV-1b (previously defined as genotype 2a/2c). In the other cases, NS3 sequencing precisely resolved the either previous undetermined/discordant subtype 1 or double genotype/subtype assignment by commercial genotyping assays. Resistance-associated variants (RAVs) to PI were detected in 31.0% of samples. This prevalence changed according to PI experience (17.1% in PI-naive patients versus 79.2% in boceprevir/telaprevir/simeprevir-failing patients). Among 96 patients with available virological outcome following boceprevir/telaprevir treatment, a trend of association between baseline NS3 RAVs and virological failure was observed (particularly for HCV-1a-infected patients: 3/21 failing patients versus 0/22 achieving sustained virological response; P = 0.11). CONCLUSIONS: HCV-NS3 sequencing provides reliable results and at the same time gives two clinically relevant pieces of information: a correct subtype/genotype assignment and the detection of variants that may interfere with the efficacy of PI.

Genotypic testing on HIV-1 DNA as a tool to assess HIV-1 co-receptor usage in clinical practice: results from the DIVA study group.

PURPOSE: We have developed a sequencing assay for determining the usage of the genotypic HIV-1 co-receptor using peripheral blood mononuclear cell (PBMC) DNA in virologically suppressed HIV-1 infected patients. Our specific aims were to (1) evaluate the efficiency of V3 sequences in B versus non-B subtypes, (2) compare the efficiency of V3 sequences and tropism prediction using whole blood and PBMCs for DNA extraction, (3) compare the efficiency of V3 sequences and tropism prediction using a single versus a triplicate round of amplification. RESULTS: The overall rate of successful V3 sequences ranged from 100 % in samples with >3,000 copies HIV-1 DNA/10(6) PBMCs to 60 % in samples with <100 copies total HIV-1 DNA /10(6) PBMCs. Analysis of 143 paired PBMCs and whole-blood samples showed successful V3 sequences rates of 77.6 % for PBMCs and 83.9 % for whole blood. These rates are in agreement with the tropism prediction obtained using the geno2pheno co-receptor algorithm, namely, 92.1 % with a false-positive rate (FPR) of 10 or 20 % and of 96.5 % with an FPR of 5.75 %. The agreement between tropism prediction values using single versus triplicate amplification was 98.2 % (56/57) of patients using an FPR of 20 % and 92.9 % (53/57) using an FPR of 10 or 5.75 %. For 63.0 % (36/57) of patients, the FPR obtained via the single amplification procedure was superimposable to all three FPRs obtained by triplicate amplification. CONCLUSIONS: Our results show the feasibility and consistency of genotypic testing on HIV-1 DNA tropism, supporting its possible use for selecting patients with suppressed plasma HIV-1 RNA as candidates for CCR5-antagonist treatment. The high agreement between tropism prediction by single and triple amplification does not support the use of triplicate amplification in clinical practice.

Snapshot on drug-resistance rate and profiles in patients with chronic hepatitis B receiving nucleos(t)ide analogues in clinical practice.

While the selection of complex HBV drug-resistance patterns on therapeutic failure can compromise the efficacy of anti-HBV therapies, recent data show that patients failing treatment without drug-resistance have a rate of virological success close to drug-naive patients. The goal of this study is defining, in clinical practice, the burden of drug-resistance mutations in a cohort of patients treated with anti-HBV drugs. Prevalence and patterns of drug-resistance were analyzed by RT-sequencing in 204 patients infected chronically: 148 experiencing virological rebound (defined as an increase in serum HBV-DNA > 20 IU/ml after achieving virological success [HBV-DNA < 20 IU/ml]), and 56 null/partial responders (always detectable serum HBV-DNA [>20 IU/ml] within 48 weeks of therapy). The highest rate of drug-resistance was observed in patients experiencing virological rebound (prevalence, 79.1%). Conversely, almost half (46.4%) null/partial responders have no evidence of drug-resistance. The rate of drug-resistance was higher in patients treated with lamivudine (76.8% [109/142]) and telbivudine (83.3% [5/6]), followed by adefovir (62.5% [15/24]), and entecavir (52.2% [12/23]). Complex mutational patterns characterized by the co-presence of rtM204V/I-rtA181T/V (impairing the efficacy of all anti-HBV drugs) were detected in four patients (2.7%) with virological rebound. Drug-resistance is the main cause of failure to therapy in patients experiencing virological rebound, supporting the need of rapid switch to anti-HBV drugs with higher genetic barrier and potency (entecavir/tenofovir). Conversely, nearly half of null/partial responders shows no evidence of drug-resistance mutations, maintaining high chance of achieving therapeutic success with the same class of drug. In this setting, genotypic resistance may help in selecting patients still carrying wild-type viruses, that may take major benefits from antiviral treatment.

Major bleeding in patients undergoing PCI and triple or dual antithrombotic therapy: a parallel-cohort study.

The combination of oral anticoagulants with dual antiplatelet therapy (DAT) in patients undergoing percutaneous coronary intervention with stent implantation (PCI-stenting) is subject to controversy due to the high risk of bleeding. In this multicenter retrospective parallel-group study, we compared the rate of adverse events in chronically anticoagulated patients who underwent PCI-stenting and were discharged on aspirin, clopidogrel and warfarin (triple antithrombotic therapy [TT] group) and were followed in Italian anticoagulation centers, with a parallel cohort of patients who underwent PCI-stenting and were discharged on DAT group. The primary endpoint was the incidence of major bleeding while the patients were in TT and DAT. A secondary endpoint was the occurrence of major ischemic adverse events (MACEs). The final cohort consisted of 229 TT patients and 231 DAT patients followed up for 6 and 7 months, respectively. There were 11 (4.8%; 9.1% patient/years) major bleeding events in the TT group (1 was fatal) as compared to 1 (0.4%; 0.7% patient/years) event in the DAT group (p = 0.003). Of the 28 (6.1%) MACE recorded during the follow-up, 12 (5.2%) occurred in the TT group and 16 (6.9%) in the DAT group. In conclusion, despite close monitoring of anticoagulated patients in dedicated centers, the major bleeding incidence remains high among unselected patients undergoing PCI-stenting and treated with TT. Any efforts to minimize these events should be pursued.

Late onset of hepatitis B virus reactivation following hematopoietic stem cell transplantation: successful treatment with combined entecavir plus tenofovir therapy.

Prophylaxis with lamivudine (LAM) is recommended for hepatitis B core antibody-positive allogenic hematopoietic stem cell transplant (HSCT) recipients, but the optimal timing for the institution and duration of the prophylaxis is still unknown. Furthermore, considering the high rate of mortality associated with hepatitis B virus reactivation (HBV-R), the most potent and long-term effective antiviral regimen should be considered. We report here a case of late onset of HBV-R after a long-term prophylaxis with LAM in a patient who underwent HSCT for non-Hodgkin lymphoma and who was successfully treated with a combination antiviral regimen including entecavir and tenofovir disoproxil fumarate.

SARS-CoV-2 mRNA vaccine BNT162b2 triggers a consistent cross-variant humoral and cellular response.

As the SARS-CoV-2 pandemic continues to rage worldwide, the emergence of numerous variants of concern (VOC) represents a challenge for the vaccinal protective efficacy and the reliability of commercially available high-throughput immunoassays. Our study demonstrates the administration of two doses of the BNT162b2 vaccine that elicited a robust SARS-CoV-2-specific immune response which was assessed up to 3 months after full vaccination in a cohort of 37 health care workers (HCWs). SARS-CoV-2-specific antibody response, evaluated by four commercially available chemiluminescence immunoassays (CLIA), was qualitatively consistent with the results provided by the gold-standard in vitro neutralization assay (NTA). However, we could not observe a correlation between the quantity of the antibody detected by CLIA assays and their neutralizing activity tested by NTA. Almost all subjects developed a SARS-CoV-2-specific T-cell response. Moreover, vaccinated HCWs developed a similar protective neutralizing antibodies response against the EU (B.1), Alpha (B.1.1.7), Gamma (P.1), and Eta (B.1.525) SARS-CoV-2 variants, while Beta (B.1.351) and Delta (B.1.617.2) strains displayed a consistent partial immune evasion. These results underline the importance of a solid vaccine-elicited immune response and a robust antibody titre. We believe that these relevant results should be taken into consideration in the definition of future vaccinal strategies.

Standardized low-molecular-weight heparin bridging regimen in outpatients on oral anticoagulants undergoing invasive procedure or surgery: an inception cohort management study.

BACKGROUND: Bridging therapy with low-molecular-weight heparin is usually recommended in patients who must stop oral anticoagulants before surgical or invasive procedures. To date, there is no universally accepted bridging regimen tailored to the patient's thromboembolic risk. This prospective inception cohort management study was designed to assess the efficacy and safety of an individualized bridging protocol applied to outpatients. METHODS AND RESULTS: Oral anticoagulants were stopped 5 days before the procedure. Low-molecular-weight heparin was started 3 to 4 days before surgery and continued for 6 days after surgery at 70 anti-factor Xa U/kg twice daily in high-thromboembolic-risk patients and prophylactic once-daily doses in moderate- to low-risk patients. Oral anticoagulation was resumed the day after the procedure with a boost dose of 50% for 2 days and maintenance doses afterward. The patients were followed up for 30 days. Of the 1262 patients included in the study (only 15% had mechanical valves), 295 (23.4%) were high-thromboembolic-risk patients and 967 (76.6%) were moderate- to low-risk patients. In the intention-to-treat analysis, there were 5 thromboembolic events (0.4%; 95% confidence interval, 0.1 to 0.9), all in high-thromboembolic-risk patients. There were 15 major (1.2%; 95% confidence interval, 0.7 to 2.0) and 53 minor (4.2%; 95% confidence interval, 3.2 to 5.5) bleeding episodes. Major bleeding was associated with twice-daily low-molecular-weight heparin administration (high-risk patients) but not with the bleeding risk of the procedure. CONCLUSIONS: This management bridging protocol, tailored to patients' thromboembolic risk, appears to be feasible, effective, and safe for many patients, but safety in patients with mechanical prosthetic valves has not been conclusively established.

Graphene oxide nanocomposite magnetic microbeads for the remediation of positively charged aromatic compounds.

Integrating graphene as an inorganic nanostructure within a hydrogel matrix enables the creation of a unique hybrid composite combining the peculiar chemical and physical properties of graphene with the high porosity and stability of hydrogels as for example agarose gel. As a consequence, the resulting material forms a double-network system providing advantages deriving from both the components. In this study, we present the synthesis of novel magnetic porous agarose-based graphene oxide microbeads for the adsorption and separation of positively charged aromatic molecules. The hydrogel-based graphene oxide beads revealed an ultrafast adsorption kinetics for positively charged aromatic dyes. We tested this material for the purification of fluorescent-tagged biomolecules. In addition, reduced graphene oxide microbeads were decorated with palladium nanoparticles, showing a high catalytic activity towards the reduction of dyes by sodium borohydride. Our results show that magnetic agarose based graphene microbeads with enhanced physical-chemical properties can be used for several biochemical applications.

Prevalence of transmitted HIV-1 drug resistance in HIV-1-infected patients in Italy: evolution over 12 years and predictors.

OBJECTIVES: Transmitted HIV-1 drug resistance (TDR) can reduce the efficacy of first-line antiretroviral therapy. PATIENTS AND METHODS: A retrospective analysis was performed to assess the prevalence and correlates of TDR in Italy over time. TDR was defined as the presence of at least one of the mutations present in the surveillance drug resistance mutation (SDRM) list. RESULTS: Among 1690 antiretroviral therapy-naive patients, the most frequent HIV subtypes were B (78.8%), CRF02_AG (5.6%) and C (3.6%). Overall, TDR was 15%. TDR was 17.3% in subtype B and 7.0% in non-B carriers (P < 0.001). TDR showed a slight, although not significant, decline (from 16.3% in 1996-2001 to 13.4% in 2006-07, P = 0.15); TDR declined for nucleoside reverse transcriptase inhibitors (from 13.1% to 8.2%, P = 0.003) but remained stable for protease inhibitors (from 3.7% to 2.5%, P = 0.12) and non-nucleoside reverse transcriptase inhibitors (from 3.7% to 5.8%). TDR to any drug was stable in B subtype and showed a decline trend in non-B. In multivariable analysis, F1 subtype or any non-B subtype, compared with B subtype, and higher HIV RNA were independent predictors of reduced odds of TDR. CONCLUSIONS: Prevalence of TDR to nucleoside reverse transcriptase inhibitors seems to have declined in Italy over time. Increased prevalence of non-B subtypes partially justifies this phenomenon.

Two different patterns of mutations are involved in the genotypic resistance score for atazanavir boosted versus unboosted by ritonavir in multiple failing patients.

OBJECTIVES: The protease inhibitor atazanavir (ATV) can be used either boosted by ritonavir (ATV300/r) or unboosted (ATV400). To date, however, genotypic resistance scores (GRSs) have been developed only for boosted-ATV. We have determined GRS associated with virologic response (VR) for both ATV300/r and ATV400 in highly pre-treated HIV-1 infected patients. PATIENTS AND METHODS: We analyzed the results of genotypic tests available 0-3 months before the initiation of an ATV-containing regimen in 159 patients with HIV-RNA >or= 500 copies/ml (ATV300/r group: 74; ATV400 group: 85) who were enrolled in the CARe study through an Early Access Program. The impact of baseline protease mutations on VR (>or= 1 log(10)copies/ml HIV-RNA decrease at 12-24 weeks) was analyzed using Fisher's exact test. Mutated protease amino acid positions (MPP) with p < 0.20 were retained for further analysis. The GRSs were determined by a step-by-step analysis using the chi(2) test for trend. RESULTS: The GRSs for ATV300/r and ATV400 revealed differing sets of mutations. For ATV300/r, 12 MPPs (10C/I/V + 32I + 34Q + 46I/L + 53L + 54A/M/V + 82A/F/I/T + 84V + 90M - 15E/G/L/V - 69K/M/N/Q/R/T/Y - 72M/ T/V; p = 1.38 x 10(-9)) were the most strongly associated with VR (VR: 100%, 78.3%, 83.3%, 75% and 0% of patients with a score of -2/-1, 0, 1, 2, and >or= 3, respectively); the last three MPPs (I15/H69/I72) were associated with a better VR. For ATV400, nine MPPs (16E + 20I/M/R/T/V + 32I + 33F/I/V + 53L/Y + 64L/M/ V + 71I/T/V + 85V + 93L/M; p = 9.42 x 10(-8)) were most strongly associated with VR (VR: 83.3%, 66.7%, 5.9%, 0% of patients with 0, 1/2, 3, and >or= 4 MPP, respectively). Differences between GRSs for ATV300/r and ATV400 may be due to different ATV drug levels (boosted vs unboosted), favoring different pathways of escape from antiviral pressure. CONCLUSIONS: Both GRSs were independent predictors of response in a multivariable logistic regression model. Nevertheless, cross-validation of these GRSs on different patient databases is required before their implementation in clinical practice.

The influence of metal nanoparticle size distribution in photoelectron spectroscopy.

We present an innovative approach to characterize small metal nanoclusters embedded in an amorphous carbon matrix. A simple mathematical relation linking binding energy shifts to the mean nanoparticle (NP) dimensions allows determination of the distribution of NP sizes by fitting the Au 4f X-ray photoemission spectrum. The NP size distributions obtained using our method are compared with those obtained from X-ray diffraction spectra.

Palladium nanoparticle functionalized graphene xerogel for catalytic dye reduction.

We report a method to synthesize a palladium-functionalized porous graphene xerogel structure. A graphene xerogel nanocomposite with a three-dimensional microstructure was obtained by chemical reduction of an aqueous dispersion of graphene oxide at mild temperature. After the graphene hydrogel has been placed in a K2PdCl4 solution, the spontaneous redox reaction between the reduced graphene and Pd2+ takes place, leading to the formation of nanohybrid materials consisting of a graphene porous matrix decorated with Pd nanoparticles. The final porosity of the material was tuned through drying the graphene hydrogel by solvent evaporation. The palladium functionalized porous graphene xerogels were successfully used for the catalytic reduction of Rhodamine 6G.

Dolutegravir (DTG)-containing regimens after receiving raltegravir (RAL) or elvitegravir (EVG): Durability and virological response in a large Italian HIV drug resistance network (ARCA).

BACKGROUND: Dolutegravir (DTG) is a next-generation HIV integrase inhibitor (INI) with an increased genetic barrier to resistance with respect to raltegravir (RAL) or elvitegravir (EVG). Few data are available on the durability of DTG-containing regimens. OBJECTIVES: We aimed at investigating the duration of the DTG-containing regimen, the occurrence of an HIV-1 RNA blip, and factors associated with DTG virological response. STUDY DESIGN: From the Antiviral Response Cohort Analysis database, we selected 89 HIV-1-positive four-class-experienced subjects who started DTG after receiving RAL or EVG. Factors associated with durability and virological response were analysed by logistic regression. RESULTS: After a median duration of 18.8 [0.4-76.2] months, 79/89 (88.8%) subjects were still on DTG. All subjects remaining on DTG at the end of follow-up had undetectable HIV-1 RNA, compared to 5/10 subjects who discontinued DTG. DTG discontinuation was less frequent in patients who had experienced ≥10 regimens (HR 0.11, p = 0.040). The probability of having an HIV-1 RNA positive value at the last follow-up significantly increased in patients with non-B HIV-1 subtype (HR 5.77, p < .001) and significantly decreased in patients with CD4 nadir >200/µL (HR 0.29, p = 0.038), with more than 10 previous regimens (HR 0.27, p = 0.040), and who harbored virus with IN mutations (HR 0.12, p = 0.023) at DTG start. CONCLUSIONS: After previous exposure to first-generation INIs, treatment with DTG showed long durability and did not show virological rebound after virological suppression. Subjects infected with a non-B HIV-1 subtype had a greater risk of having detectable HIV-1 RNA at the last observation.

OC-15 - Risk factors for cancer development after idiopathic venous thromboembolism.

INTRODUCTION: Idiopathic venous thromboembolism (VTE) is associated with the risk of cancer but the risk factors for cancer development in such patients are still uncertain. AIM: To assess risk factors for the development of cancer after a standard course of anticoagulation in patients with first episode of idiopathic VTE. MATERIALS AND METHODS: Subjects were enrolled in the three large prospective multicentre studies: PROLONG (NEJM 2006) PROLONG II (Blood 2010) and DULCIS (Blood 2014). Women whose index event was hormone related were excluded from the analysis. The development of cancer was recorded during a 2-year follow-up. RESULTS: 1,805 patients were enrolled (M/F: 510/453), mean age: 62, median: 67; range:18-87 years). Cancer developed in 55 patients (3% ; 1.7% pt-years) of whom 15 (2.0%; 1.1% pt-years) had PE with or without DVT and 40 (3.8%; 2.1% pt-years) had DVT without PE (p=0.03). The development of cancer was associated with DVT without PE (HR:1.8; 95% CI: 1.1-3.3) and age >65 (HR: 2.5; 95%: 1.3-4.9). Among patients with DVT, with or without PE, the development of cancer was associated with the presence of residual vein obstruction>4mm (RVO) at compression ultrasound (HR: 1.8, 95% CI: 1.1-3.3) and age>65 (HR: 2.8; 95% CI: 1.3-6.2). CONCLUSIONS: Age>65 years, DVT without PE and the presence of RVO are significantly associated with the risk of developing cancer after a first episode of idiopathic VTE over a two-year follow-up.

Cytosolic 5'-nucleotidase hyperactivity in erythrocytes of Lesch-Nyhan syndrome patients.

Lesch-Nyhan syndrome is a metabolic-neurological syndrome caused by the X-linked deficiency of the purine salvage enzyme hypoxanthine-guanine phosphoribosyltransferase (HGPRT). Metabolic consequences of HGPRT deficiency have been clarified, but the connection with the neurological manifestations is still unknown. Much effort has been directed to finding other alterations in purine nucleotides in different cells of Lesch-Nyhan patients. A peculiar finding was the measure of appreciable amount of Z-nucleotides in red cells. We found significantly higher IMP-GMP-specific 5'-nucleotidase activity in the erythrocytes of seven patients with Lesch-Nyhan syndrome than in healthy controls. The same alteration was found in one individual with partial HGPRT deficiency displaying a severe neurological syndrome, and in two slightly hyperuricemic patients with a psychomotor delay. Since ZMP was a good substrate of 5'-nucleotidase producing Z-riboside, we incubated murine and human cultured neuronal cells with this nucleoside and found that it is toxic for our models, promoting apoptosis. This finding suggests an involvement of the toxicity of the Z-riboside in the pathogenesis of neurological disorders in Lesch-Nyhan syndrome and possibly in other pediatric neurological syndromes of uncertain origin.

Genotyping in HIV drug resistance mutations: epidemiology in 145 patients.

The epidemiology of HIV-1 genomic mutations causing antiretroviral drug resistance, in 145 HIV-1 infected patients were obtained using a new sequencing technique. All patients were in a follow up treatment for at least 4 months with all drugs available in clinical practice in accordance to international guidelines. The percentage of the mutations were calculated both on the number of all participants and on the number of patients who received the drugs selecting for that specific resistance. It was possible then to evaluate patients who showed the mutation without receiving the drug. We consider this new sequencing method reliable and hopeful in clinical practice, giving the opportunity for a guided therapy for the single patient and in detecting and monitoring the antiretroviral drug resistance mutations in the pertinent geographic area following a periodic surveillance program.

Pneumocystis carinii diagnosis: an update.

From 1994 to date we have been using the internal transcribed spacers (ITSs) nested polymerase chain reaction (PCR) to investigate the possibility of diagnosing Pneumocystis carinii pneumonia on non-invasive samples collected from HIV-positive patients with pulmonary involvement. The objectives were: (1) to test the sensitivity, specificity and prognostic value of PCR in diagnosis and follow up of PCP; (2) to investigate the eventual occurrence and role of asymptomatic carriers of P. carinii; (3) to evaluate the prognostic significance of blood PCR positivity versus respiratory samples; (4) to verify the occurrence of exogenous infections or endogenous reactivations in cases of recurrent P. carinii pneumonia; and (5) to study the possible correlation between P. carinii genotype identified and capability of blood dissemination, prior prophylactic treatments, clinical parameters and outcome of the patients.