Nicolas Argy

Outbreak of Pneumocystis jirovecii Infection Among Heart Transplant Recipients: Molecular Investigation and Management of an Interhuman Transmission

Background An outbreak of Pneumocystis jirovecii pneumonia (PCP) occurred among heart transplant recipients (HTR) at the outpatient clinic of a university hospital, from March to September 2015. Clinical, therapeutic, biological, and molecular data were analyzed to determine its origin and control the outbreak. Methods Clinical and biological data regarding all HTR followed in the outpatient clinic were collected. PCP diagnosis was based on microscopy and real-time polymerase chain reaction (PCR). Investigations were performed by building a transmission map, completed by genotyping Pneumocystis isolates and by a control of chemoprophylaxis observance. Asymptomatic exposed patients were screened for colonization using real-time PCR. Results Among 124 HTR, 7 PCP cases were confirmed. Screening identified 3 additional patients colonized by P. jirovecii. All patients were cured, and no further cases were identified after trimethoprim-sulfamethoxazole prophylaxis was introduced in the entire cohort. Genotyping demonstrated the same strain in all PCP cases and colonized patients. All cases were linked with possible transmission chains from 2 possible index patients. Interhuman transmission was significantly associated with more frequent visits in the outpatient clinic. Six cases were receiving atovaquone as a prophylaxis. The occurrence of PCP was significantly associated with atovaquone prophylaxis. Conclusions This is the first outbreak with detailed molecular analysis in HTR so far. Genotyping and transmission chain confirmed interhuman transmission in all colonized/infected PCP cases. Outpatient clinic layout and high encounters probably caused this PCP cluster, which was controlled after systematic trimethoprim-sulfamethoxazole prophylaxis in exposed patients.

Measuring the Plasmodium falciparum HRP2 protein in blood from artesunate-treated malaria patients predicts post-artesunate delayed hemolysis

Previously parasitized erythrocytes in patients with severe malaria retain the parasite protein HRP2, which can be used to predict hemolysis induced by the drug artesunate. A quick test to predict artesunate-induced anemia Anemia frequently affects patients treated for severe malaria with artemisinin drugs. Artemisinin kills malaria parasites, which are then expelled from infected red blood cells. These “deparasitized” red blood cells persist in the blood but are later destroyed, resulting in anemia. Ndour et al. now show that the deparasitized red blood cells retain the parasite protein HRP2, which explains why HRP2 can still be detected in patients after the malaria infection has been cleared. The amount of HRP2 in the blood immediately after treatment with artemisinin correlates with the number of deparasitized red blood cells in the circulation. HRP2 can be measured with a rapid diagnostic dipstick test that then can be used to predict the risk for delayed hemolysis and anemia in malaria patients treated with artemisinin. Artesunate, the recommended drug for severe malaria, rapidly clears the malaria parasite from infected patients but frequently induces anemia—called post-artesunate delayed hemolysis (PADH)—for which a simple predictive test is urgently needed. The underlying event in PADH is the expulsion of artesunate-exposed parasites from their host erythrocytes by pitting. We show that the histidine-rich protein 2 (HRP2) of the malaria parasite Plasmodium falciparum persists in the circulation of artesunate-treated malaria patients in Bangladesh and in French travelers who became infected with malaria in Africa. HRP2 persisted in whole blood (not plasma) of artesunate-treated patients with malaria at higher levels compared to quinine-treated patients. Using an optimized membrane permeabilization method, HRP2 was observed by immunofluorescence, Western blotting, and electron microscopy to persist in once-infected red blood cells from artesunate-treated malaria patients. HRP2 was deposited at the membrane of once-infected red blood cells in a pattern similar to that for ring erythrocyte surface antigen (RESA), a parasite invasion marker. On the basis of these observations, we developed a semiquantitative titration method using a widely available HRP2-based rapid diagnostic dipstick test. Positivity on this test using a 1:500 dilution of whole blood from artesunate-treated patients with malaria collected shortly after parasite clearance predicted subsequent PADH with 89% sensitivity and 73% specificity. These results suggest that adapting an existing HRP2-based rapid diagnostic dipstick test may enable prediction of PADH several days before it occurs in artesunate-treated patients with malaria.

Autochthonous Case of Eosinophilic Meningitis Caused by Angiostrongylus cantonensis, France, 2016

We report a case of a 54-year-old Moroccan woman living in France diagnosed with eosinophilic meningitis caused by Angiostrongylus cantonensis. Diagnosis was based on clinical symptoms and confirmed by testing of serum and cerebrospinal fluid samples. Physicians should consider the risk for A. cantonensis infection outside of endemic areas.

Pneumocystis Cytochrome b Mutants Associated With Atovaquone Prophylaxis Failure as the Cause of Pneumocystis Infection Outbreak Among Heart Transplant Recipients

Background Although trimethoprim-sulfamethoxazole is the more efficient drug for prophylactic and curative treatment of pneumocystosis, atovaquone is considered a second-line prophylactic treatment in immunocompromised patients. Variations in atovaquone absorption and mutant fungi selection after atovaquone exposure have been associated with atovaquone prophylactic failure. We report here a Pneumocystis jirovecii cytochrome b (cyt b) mutation (A144V) associated with such prophylactic failure during a pneumocystosis outbreak among heart transplant recipients. Methods Analyses of clinical data, serum drug dosage, and molecular modeling of the P. jirovecii Rieske-cyt b complex were performed to investigate these prophylactic failures. Results The cyt b A144V mutation was detected in all infected, heart transplant recipient patients exposed to atovaquone prophylaxis but in none of 11 other immunocompromised, infected control patients not treated with atovaquone. Serum atovaquone concentrations associated with these prophylactic failures were similar than those found in noninfected exposed control patients under a similar prophylactic regimen. Computational modeling of the P. jirovecii Rieske-cyt b complex and in silico mutagenesis indicated that the cyt b A144V mutation might alter the volume of the atovaquone-binding pocket, which could decrease atovaquone binding. Conclusions These data suggest that the cyt b A144V mutation confers diminished sensitivity to atovaquone, resulting in spread of Pneumocystis pneumonia among heart transplant recipients submitted to atovaquone prophylaxis. Potential selection and interhuman transmission of resistant P. jirovecii strain during atovaquone prophylactic treatment has to be considered and could limit its extended large-scale use in immucompromised patients.

Distinction of Plasmodium ovale wallikeri and Plasmodium ovale curtisi using quantitative Polymerase Chain Reaction with High Resolution Melting revelation

Plasmodium ovale curtisi (Poc) and Plasmodium ovale wallikeri (Pow) have been described as two distinct species, only distinguishable by molecular methods such as PCR. Because of no well-defined endemic area and a variable clinical presentation as higher thrombocytopenia and nausea associated with Pow infection and asymptomatic forms of the pathology with Poc infection, rapid and specific identification of Plasmodium ovale curtisi and Plasmodium ovale wallikeri are needed. The aim of the study was to evaluate a new quantitative real-time PCR coupled with high resolution melting revelation (qPCR-HRM) for identification of both species. Results were compared with a nested-PCR, considered as a gold standard for Pow and Poc distinction. 356 samples including all human Plasmodium species at various parasitaemia were tested. The qPCR-HRM assay allowed Poc and Pow discrimination in 66 samples tested with a limit of detection evaluated at 1 parasite/µL. All these results were concordant with nested-PCR. Cross-reaction was absent with others blood parasites. The qPCR-HRM is a rapid and convenient technique to Poc and Pow distinction.

A rare fungal infection: Phaehyphomycosis due to Veronaea botryosa and review of literature

We report a rare case of phaehyphomycosis in a 71-year-old heart transplant recipient Togo native patient. Four months after the transplant, he presented painless nodules on the right heel with superficial ulceration. The polyphasic identification uncovered a rare cause of phaehyphomycose: V. botryosa. The treatment combined surgical excision of the lesions and anti-fungal therapy with posaconazole. We discussed eleven reported cases in literature since 1990.