Genotyping of Pneumocystis jiroveci pneumonia in Italian AIDS patients. Clinical outcome is influenced by dihydropteroate synthase and not by internal transcribed spacer genotype.

BACKGROUND: Two Pneumocystis jiroveci independent genomic regions, internal transcribed spacer (ITS) 1 and ITS2, and dihydropteroate synthase (DHPS) gene have been used for typing a cohort of HIV-infected Italian patients with P jiroveci pneumonia (PcP). METHODS: Bronchoalveolar lavage samples isolated from 207 HIV-infected adults were ITS and DHPS genotyped by DNA sequencing and by restriction fragment length polymorphism analysis, respectively. Mutant DHPS samples were cloned and ITS typed. Data on severity, treatment, and outcome of PcP were obtained by chart review. RESULTS: High diversity with 46 different ITS genotypes was observed. At the DHPS locus, 9.1% of samples analyzed were found to be mutated. A correlation was observed between DHPS mutants and greater severity of PcP, as defined by higher lactate dehydrogenase (P = 0.015) and need for intubation (P = 0.002), and worse outcomes, as defined by failure of sulfa treatment (P = 0.04), death, and/or relapse of PcP (P = 0.008). There was a significant difference in ITS genotype patterns between DHPS wild-type and mutants (P = 0.028). CONCLUSIONS: The present data suggest the absence of a correlation between P jiroveci ITS types and specific clinical characteristics. DHPS mutations correlate with possible failure of anti-P jiroveci sulfa therapy, and a trend of association is shown between DHPS mutations and some clinical PcP features.

Assessment of immune reconstitution to Pneumocystis carinii in HIV-1 patients under different highly active antiretroviral therapy regimens.

The introduction of protease inhibitors (PIs) gave a dramatic drop in AIDS-related opportunistic events, mainly due to induced immune reconstitution. Discontinuation of prophylaxis against Pneumocystis carinii is considered safe when CD4 > 200 cells/mm(3). Ideally, we should have specific functional tests for HIV-1-related decisions. We examined viro-immunological profiles, clinical outcome and lymphocyte proliferation (LP) to P. carinii and other antigens in 108 subjects: 28 AIDS presenters with P. carinii pneumonia (PCP) (CD4 < 200 cells/mm(3)), 22 untreated asymptomatic HIV-1-infected patients (CD4 > 200 cells/mm(3)), 44 HIV-1-infected patients immune-reconstituted on antiretroviral regimens and 14 HIV-1-uninfected healthy controls. As regards viral load, there was no significant difference in therapy duration, nadir, or actual CD4, CD8, natural killer or B cell counts in immune-reconstituted patients receiving protease inhibitor (PI)-based versus those receiving PI-sparing antiretroviral regimens. Among subjects showing abnormally low P. carinii-specific LP, three patients receiving a non-nucleoside reverse transcriptase inhibitor (nNRTI) developed PCP despite having CD4 > 250 cells/mm(3). P. carinii-specific LP could be considered for doubtful situations, i.e. for a safer clinical decision of discontinuing or restarting prophylaxis in patients with a low CD4 nadir or experiencing a sudden CD4 decrease under highly active antiretroviral therapy (HAART). HIV-1 PIs, having in vitro aspecific effects against Pneumocystis, could play a clinically significant anti-opportunistic role, thus offering a further benefit in heavily immunosuppressed patients during early stages of antiretroviral therapy.