Abstract Objective: The aim of this study was to analyze and identify documented infections and possible risk factors for Clostridioides difficile infections in children with cancer. Methods: This is a retrospective case-control study, carried out in a pediatric cancer hospital, covering the years 2016–2019. Matching was performed by age and underlying disease, and for each case, the number of controls varied from 1 to 3. Logistic regression models were used to assess risk factors. Results: We analyzed 63 cases of documented infection by C. difficile and 125 controls. Diarrhea was present in all cases, accompanied by fever higher than 38°C in 52.4% of the patients. Mortality was similar among cases (n=4; 6.3%) and controls (n=6; 4.8%; p=0.7). In all, 71% of patients in the case group and 53% in the control group received broad-spectrum antibiotics prior to the infection. For previous use of vancomycin, the Odds Ratio for C. difficile infection was 5.4 (95% confidence interval [95%CI] 2.3–12.5); for meropenem, 4.41 (95%CI 2.1–9.2); and for cefepime, 2.6 (95%CI 1.3–5.1). For the antineoplastic agents, the Odds Ratio for carboplatin was 2.7 (95%CI 1.2–6.2), melphalan 9.04 (95%CI 1.9–42.3), busulfan 16.7 (95%CI 2.1–134.9), and asparaginase 8.97 (95%CI 1.9–42.9). Conclusions: C. difficile symptomatic infection in children with cancer was associated with previous hospitalization and the use of common antibiotics in cancer patients, such as vancomycin, meropenem, and cefepime, in the last 3 months. Chemotherapy drugs, such as carboplatin, melphalan, busulfan, and asparaginase, were also risk factors.

RESUMO Objetivo: Analisar e identificar infecções documentadas e possíveis fatores de risco para infecções por Clostridioides difficile em crianças com câncer. Métodos: Estudo retrospectivo caso-controle em um hospital pediátrico oncológico, que abrangeu os anos de 2016–2019. O pareamento foi realizado por idade e doença de base e, para cada caso, o número de controles variou de um a três. Modelos de regressão logística foram utilizados para avaliar os fatores de risco. Resultados: Analisamos 63 casos de infecção documentados por C. difficile e 125 controles. A diarreia esteve presente em todos os casos, acompanhada de febre acima de 38°C em 52,4% dos pacientes. A mortalidade foi semelhante entre casos (n=4, 6,3%) e controles (n=6, 4,8%; p=0,7). No grupo caso, 71% dos pacientes e, no grupo controle, 53% deles receberam antibióticos de amplo espectro antes da infecção. Para uso prévio de vancomicina, a Odds Ratio para infecção por C. difficile foi de 5,4 (intervalo de confiança [IC95%] 2,3–12,5); para meropenem, 4,41 (IC95% 2,1–9,2) e, para cefepima, 2,6 (IC95% 1,3–5,1). Para os agentes antineoplásicos, a razão de chances para carboplatina foi de 2,7 (IC95% 1,2–6,2), para melfalano de 9,04 (IC95% 1,9-42,3), para bussulfano de 16,7 (IC95% 2,1–134,9) e, para asparaginase, de 8,97 (IC95% 1,9–42,9). Conclusões: A infecção sintomática por C. difficile em crianças com câncer associou-se à internação prévia e ao uso de antibióticos como vancomicina, meropenem e cefepime nos últimos três meses. Os quimioterápicos carboplatina, melfalano, bussulfano e asparaginase também foram fatores de risco.

Soroprevalence for Hepatitis C virus is reported as 2.12% in Northern Brazil, with about 50% of the patients exhibiting a sustained virological response (SVR). Aiming to associate polymorphisms in Killer Cell Immunoglobulin-like Receptors (KIR) with chronic hepatitis C and therapy responses we investigated 125 chronic patients and 345 controls. Additionally, 48 ancestry markers were genotyped to control for population stratification. The frequency of the KIR2DL2 and KIR2DL2+HLA-C Asp80 gene and ligand was higher in chronic infected patients than in controls (p < 0.0009, OR = 3.4; p = 0.001, OR = 3.45). In fact, KIR2DL3 is a weaker inhibitor of NK activity than KIR2DL2, which could explain the association of KIR2DL2 with chronic infection. Moreover, KIR2DS2 and KIR2DS2+HLA-C Asp80 (p < 0.0001, OR = 2.51; p = 0.0084, OR = 2.62) and KIR2DS3 (p < 0.0001; OR = 2.57) were associated with chronic infection, independently from KIR2DL2. No differences in ancestry composition were observed between control and patients, even with respect to therapy response groups. The allelic profile KIR2DL2/KIR2DS2/KIR2DS3 was associated with the chronic hepatitis C (p < 0.0001; OR = 3). Furthermore, the patients also showed a higher mean number of activating genes and a lower frequency of the homozygous AA profile, which is likely secondary to the association with non-AA and/or activating genes. In addition, the KIR2DS5 allele was associated with SVR (p = 0.0261; OR = 0.184).The ancestry analysis of samples ruled out any effects of population substructuring and did not evidence interethnic differences in therapy response, as suggested in previous studies.