Impact factors of Blastocystis hominis infection in persons living with human immunodeficiency virus: a large-scale, multi-center observational study from China.

BACKGROUND: Blastocystis hominis (Bh) is zoonotic parasitic pathogen with a high prevalent globally, causing opportunistic infections and diarrhea disease. Human immunodeficiency virus (HIV) infection disrupts the immune system by depleting CD4+ T lymphocyte (CD4+ T) cell counts, thereby increasing Bh infection risk among persons living with HIV (PLWH). However, the precise association between Bh infection risk and HIV-related biological markers and treatment processes remains poorly understood. Hence, the purpose of the study was to explore the association between Bh infection risk and CD4+ T cell counts, HIV viral load (VL), and duration of interruption in antiviral therapy among PLWH. METHODS: A large-scale multi-center cross-sectional study was conducted in China from June 2020 to December 2022. The genetic presence of Bh in fecal samples was detected by real-time fluorescence quantitative polymerase chain reaction, the CD4+ T cell counts in venous blood was measured using flowcytometry, and the HIV VL in serum was quantified using fluorescence-based instruments. Restricted cubic spline (RCS) was applied to assess the non-linear association between Bh infection risk and CD4+ T cell counts, HIV VL, and duration of interruption in highly active antiretroviral therapy (HARRT). RESULTS: A total of 1245 PLWH were enrolled in the study, the average age of PLWH was 43 years [interquartile range (IQR): 33, 52], with 452 (36.3%) being female, 50.4% (n = 628) had no immunosuppression (CD4+ T cell counts > 500 cells/µl), and 78.1% (n = 972) achieved full virological suppression (HIV VL < 50 copies/ml). Approximately 10.5% (n = 131) of PLWH had interruption. The prevalence of Bh was found to be 4.9% [95% confidence interval (CI): 3.8-6.4%] among PLWH. Significant nonlinear associations were observed between the Bh infection risk and CD4+ T cell counts (Pfor nonlinearity < 0.001, L-shaped), HIV VL (Pfor nonlinearity < 0.001, inverted U-shaped), and duration of interruption in HARRT (Pfor nonlinearity < 0.001, inverted U-shaped). CONCLUSIONS: The study revealed that VL was a better predictor of Bh infection than CD4+ T cell counts. It is crucial to consider the simultaneous surveillance of HIV VL and CD4+ T cell counts in PLWH in the regions with high level of socioeconomic development. The integrated approach can offer more comprehensive and accurate understanding in the aspects of Bh infection and other opportunistic infections, the efficacy of therapeutic drugs, and the assessment of preventive and control strategies.

Symptomatic and Asymptomatic Protist Infections in Hospital Inpatients in Southwestern China.

Cryptosporidium spp., Entamoeba histolytica, Giardia duodenalis, and Blastocystis sp. infections have been frequently reported as etiological agents for gastroenteritis, but also as common gut inhabitants in apparently healthy individuals. Between July 2016 and March 2017, stool samples (n = 507) were collected from randomly selected individuals (male/female ratio: 1.1, age range: 38-63 years) from two sentinel hospitals in Tengchong City Yunnan Province, China. Molecular (PCR and Sanger sequencing) methods were used to detect and genotype the investigated protist species. Carriage/infection rates were: Blastocystis sp. 9.5% (95% CI: 7.1-12.4%), G. duodenalis 2.2% (95% CI: 1.1-3.8%); and E. histolytica 2.0% (95% CI: 0.9-3.6%). Cryptosporidium spp. was not detected at all. Overall, 12.4% (95% CI: 9.7-15.6) of the participants harbored at least one enteric protist species. The most common coinfection was E. histolytica and Blastocystis sp. (1.0%; 95% CI: 0.3-2.2). Sequence analyses revealed that 90.9% (10/11) of the genotyped G. duodenalis isolates corresponded to the sub-assemblage AI. The remaining sequence (9.1%, 1/11) was identified as sub-assemblage BIV. Five different Blastocystis subtypes, including ST3 (43.7%, 21/48), ST1 (27.1%, 13/48), ST7 (18.8%, 9/48), ST4 (8.3%, 4/48), and ST2 (2.1%, 1/48) were identified. Statistical analyses confirmed that (i) the co-occurrence of protist infections was purely random, (ii) no associations were observed among the four protist species found, and (iii) neither their presence, individually or jointly, nor the patient's age was predictors for developing clinical symptoms associated with these infections. Overall, these protist mono- or coinfections are asymptomatic and do not follow any pattern.

[Observation on growth status of Blastocystis hominis in three media].

OBJECTIVE: To observe the growth situation of Blastocystis hominis in vitro and select the optimal method for cultivation of B. hominis in different media. METHODS: Ten positive stools with B. hominis were inoculated in three different media for cultivating, namely 1640, Jone's medium and vitro medium. And the stools with good growth status and high quantities of B. hominis were chosen to inoculate in the three media with equal amount after subcultivation, and the number of B. hominis was counted every 24 h for ten days, and the morphological changes and growth status were also observed. RESULTS: The densities of B. hominis in the 1640 and Jone's medium were higher than that in the vitro medium 48 h after the inoculation. The same stool sample was inoculated to the three different media and observed for ten days, and the results indicated that the growth of B. hominis presented regular changes in the three media, the growth peaks were on the third, sixth and ninth day post inoculation; and the density of B. hominis was the highest in the Jone's medium. The morphology of B. hominis was the clearest and most dynamic in the vitro medium, while various reproductive forms were observed in the Jone's medium. CONCLUSION: Jone's medium is suitable for the growth of B. hominis and can be the first choice for the cultivation of B. hominis in vitro, and vitro medium is the best medium for observing the growth situation of B. hominis.

[Infection of Giardia lamblia in HIV-Infected Individuals and in Kindergarden Children in Rural Area of Anhui and Genotype Analysis].

Objective: To understand the situation of Giardia lamblia infection in HIV-infected individuals and in kindergarden children in rural area of Anhui Province and analyze the genotype of the parasite. Methods: HIV-infected individuals registered in an AIDS treatment facility and children in a local kindergarden were included in this study during April 24 and May 9, 2015. The feces were collected, stained by iodine solution, and examined by microscopy. DNA was extracted from the positive feces, and nested PCR was performed to amplify the triosephosphate isomerase（tpi） gene of G. lamblia. The products were sequenced. The phylogenetic tree was constructed with BLAST, ClustalX 1.83 and MEGA6.0 softwares for analysis of homology and phylogeny. Results: One hundred and twenty-seven HIV-infected individuals and 125 kindergarden children were included. G. lamblia infection was found in three children and one HIV-infected individual. The infection detection rate in children and HIV patients was 2.40% （3/125） and 0.79% （1/127）, respectively （P>0.05）. Feces of the three infected children was soft, and no symptoms of diarrhea and stomachache were complained. Feces of the HIV-infected individual was washy, and symptoms like diarrhea, stomachache, weakness and weight loss were reported. PCR produced a specific band at 500 bp for the four persons. The sequencing results further confirmed infection in these four persons. The duplicate samples of the infected HIV patient had a 79% sequence similarity, and were 79% and 98% homologous to the Shanghai human strain of G. lamblia (GenBank accession No: KF271445), respectively. The samples of the 3 children had a 99% similarity, and all were 79% homologous to the Shanghai human strain of G. lamblia. The phylogenetic tree showed that the isolate from the HIV patient was mixed genotype of A+B, while those from the 3 children were all assemblage A. There was a high similarity between the isolates. Conclusions: There is Giardia infections in HIV patients and kindergarden children in the area. The genotype of the isolate from the HIV individual is mixed assemblage A+B while those from the children are assemblage A.