Molecular Diagnosis of Toxoplasmosis in Immunocompromised Patients: a 3-Year Multicenter Retrospective Study

Abstract

T oxoplasmosis is a widespread parasitic infection that is frequently asymptomatic in immunocompetent patients. However, this obligate intracellular protozoan parasite can evade the immune system (1, 2) and persist for the life of its host in cyst form, predominantly in the brain, retina, and muscles. Reactivation of latent cysts may occur when the immune system fails to maintain cytokine pressure, which mainly relies on gamma interferon (IFN-␥) (3). Cyst reactivation can lead to ocular toxoplasmosis, cerebral toxoplasmosis (CT), or disseminated toxoplasmosis, which involves most frequently the lungs but potentially all organs. Failure of an efficient Th1 immune response mainly results from acquired immunosuppression, through HIV infection or immunosuppressive therapy. Both primary acquired and reactivated infections are life-threatening in immunocompromised patients (ICPs). Definitive diagnosis can be obtained by the detection of parasites in blood, cerebrospinal fluid (CSF), bronchoalveolar lavage (BAL) fluid, or virtually any tissue by using PCR, which is the most sensitive method (4).Prevention of CT in patients with HIV is an object of consensus, and guidelines recommend co-trimoxazole (sulfamethoxazole-trimethoprim) chemoprophylaxis in Toxoplasma-seropositive patients when CD4 ϩ cell counts fall below 200 cells/l (4), a prophylactic regimen which also protects patients from Pneumocystis jirovecii pneumonia. Nevertheless, toxoplasmosis remains Citation Robert-Gangneux F, Sterkers Y, Yera H, Accoceberry I, Menotti J, Cassaing S, Brenier-Pinchart M-P, Hennequin C, Delhaes L, Bonhomme J, Villena I, Scherer E, Dalle F, Touafek F, Filisetti D, Varlet-Marie E, Pelloux H, Bastien P. 2015. Molecular diagnosis of toxoplasmosis in immunocompromised patients: a 3-year multicenter retrospective study.

The Laboratory Diagnosis in Toxoplasma Infection

“…For a pre-natal diagnosis, the reported sensibility goes from 64 to 97.4% with a predictive negative value of 87.7-99.7%, respectively; in case of patients with AIDS and toxoplasmosis, the reported sensibility goes from 13 to 87.5% [49]. With the detection of the sequence REP 529-bp, a sensibility of 100% has been reported in amniotic luids [48]. The sequence REP 529-bp is having an increase in the utility for the diagnosis of T. gondii by PCR since it demonstrates greater sensibility, possibly the high number of repetitions in the parasites sequence increases the possibilities of detection.…”

“…In patients with AIDS, the detection of T. gondii by PCR in cerebrospinal liquid has shown diferent sensibilities, reaching to 87% of sensibility when the sample is taken soon enough preferably during the irst 3 days and a maximum of 7 days after starting the speciic treatment [48].…”

“…Other sequences of unique copy, which are used in investigation laboratories mainly for genotyping purposes are SAG1, SAG2, SAG3, SAG4 and GRA4 genes [45]. The polymerase chain reaction (PCR) is a very valuable diagnosis method in acute infections, when the parasite crosses placental barrier and infects the foetus or on infected patients with AIDS and other immunosuppression or reactivation of the parasite [46][47][48]. Unfortunately, it is diicult to have a conidentially valor in the PCR assays.…”

Human toxoplasmosis: a comparative evaluation of the diagnostic potential of recombinant Toxoplasma gondii ROP5 and ROP18 antigens

“…The presence of the parasite can be established by the detection of specific nucleic acids (Robert-Gangneux et al, 2015), but the routinely used diagnostic methods are mostly based on the serological recognition of specific IgG and IgM antibodies. IgM antibodies are produced during the first week of infection, preceding the synthesis of specific IgG antibodies, and usually become undetectable after a variable period of time.…”

Detection of Toxoplasma gondii in a free-ranging giant anteater

“…Thus, diagnosis of T. gondii by PCR using peripheral blood to detect DNA is imperative in cases in which confirmation of parasitemia in the host is necessary, especially in those with immunological deficiency (ROBERT-GANGNEUX, 2015). In addition, PCR also allows diagnosis in animals with high sensitivity to protozoan infection (which can develop fatal toxoplasmosis) and early detection; although, in the acute phase, prior to antibody production.…”