Infections in the compromised child

Immunocompromised Seroprevalence and Course of Illness of SARS-CoV-2 in One Pediatric Quaternary Care Center

BACKGROUND

The burden of coronavirus disease 2019 (COVID-19) is poorly understood in pediatric patients due to frequent asymptomatic and mild presentations. Additionally, the disease prevalence in pediatric immunocompromised patients remains unknown.

METHODS

This cross-sectional study tested convenience samples from pediatric patients who had clinically indicated lab work collected and an immunocompromising condition, including oncologic diagnoses, solid organ transplant (SOT), bone marrow transplant, primary immunodeficiency, and rheumatologic conditions or inflammatory bowel disease on systemic immunosuppression, for the presence of antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

RESULTS

We tested sera from 485 children and observed SARS-CoV-2 seroprevalence of 1.0% (Confidence Interval [CI] 95%: 0.3%-2.4%). Two patients were positive by nasopharyngeal (NP) swab Reverse transcriptase polymerase chain reaction (RT-PCR), but only 1 seroconverted. Patients with oncologic diagnoses or SOT were most likely to be tested for COVID-19 when presenting with respiratory illness as compared with other groups.

CONCLUSIONS

Seroprevalence of antibodies to SARS-CoV-2 in immunocompromised children was similar to that of an immunocompetent pediatric population (0.6%, CI 95%: 0.3%-1.1%), suggesting an adequate antibody response. However, none of the patients who tested positive for antibodies or via NP RT-PCR had more than a mild illness course and 2 patients did not have any reported illness, suggesting that SARS-CoV-2 may not cause a worse clinical outcome in immunosuppressed children, in contrast to immunocompromised adults.

Successful treatment in a child with anaplastic large cell lymphoma and coexistence of pulmonary tuberculosis

A 13-year-old girl was admitted to our department with a history of severe pain of her left axilla and fever. On physical examination, a block of lymph nodes in her left axilla, diffuse papular rash, and red-violet swelling of her supraclavicular and subclavian region were noted. Imaging investigations revealed left axillar and supraclavicular lymphadenopathy and a small nodular shade in the upper lobe of her left lung. A biopsy from an axillary lymph node established the diagnosis of anaplastic large cell lymphoma (ALCL), whereas DNA of Mycobacterium tuberculosis was detected by polymerase chain reaction (PCR) in the same tissue biopsy. Patient was started on chemotherapy for ALCL and achieved remission of all initially involved fields. Nevertheless, two new nodular lesions were detected in the left lower lobe. Biopsy revealed granulomas, and PCR was positive for M. tuberculosis. Our patient received treatment with the combination of isoniazid and rifampin (12 months), pyrazinamide (the first 2 months), and maintenance chemotherapy for her ALCL for one year simultaneously. Four years later, she is disease free for both mycobacterial infection and lymphoma. We are reporting this successful management of mycobacterial infection in a patient with ALCL despite intensive chemotherapy that the patient received at the same time.

Effects of multidose combination chemotherapy on the humoral immune system

Patients receiving multidose combination chemotherapy are at risk for severe, life-threatening infections, caused by among others encapsulated bacteria like Streptococcus pneumoniae. The splenic marginal zone is essential in the initiation of immune responses to S. pneumoniae. We analyzed effects of multidose combination chemotherapy on B-cell subpopulations. Immune response capacity was evaluated by using Pneumovax (PPS) or Tetavax (TT) as antigenic challenge. Three days after finishing therapy, all B-cell subpopulations in bone marrow and spleen were severely reduced, including the mature marginal zone B-cell population. When analyzing the anti-PPS immune response capacity at 3 days after finishing therapy, we found that the IgM antibody levels did not differ significantly from control immunized rats. The IgG antibody levels were significantly lower compared to control immunized rats but still significantly higher compared to unimmunized rats. The depletion of marginal zone B cells by multidose combination chemotherapy most likely contributes to the prolonged period that patients are at risk for developing severe infections after chemotherapy, despite the capacity to generate sufficient antibody levels. It is conceivable that the local (temporary) loss of immunological memory, together with the supposed inability to generate a humoral response in a short time frame, plays an important role in this vulnerability.

After chemotherapy, functional humoral response capacity is restored before complete restoration of lymphoid compartments

Chemotherapy has, besides the beneficial effects, several adverse effects. Suppression of the immune system is one of the most important problems. Infections caused by encapsulated bacteria like Streptococcus pneumoniae are responsible for a major part of infectious problems during and after treatment. The splenic marginal zone is essential in the initiation of an immune response to encapsulated bacteria. In this study, we analysed the effects of three different cytostatic agents on humoral immune responses. We found a reduced, but detectable immune response capacity at two days after treatment although the marginal zone B cell population is severely reduced at this time point. Twenty-four days after cessation of treatment, the immune response capacity was largely restored although lymphoid compartments were still not completely restored at that time point. Apparently, the presence of only few marginal zone B cells is sufficient to evoke a rise in antibody titres and although antibody titre increases are low, even small rises are most likely clinically relevant.

Slow recovery of follicular B cells and marginal zone B cells after chemotherapy: implications for humoral immunity

Although most chemotherapeutic agents are known to cause primarily reduction or suppression of immune responses, surprisingly little is known about the influence of cytostatic agents on lymphoid tissue compartments such as the splenic marginal zone. The marginal zone plays an important role in the defence against encapsulated bacteria, which are potential candidates for postchemotherapeutic infections. We studied the effect of three different cytostatic agents (cisplatin, methotrexate, and cyclophosphamide) on B cell subpopulations in a rat model. Rats received a single dose of a single cytostatic agent and were sacrificed at different time points after treatment. Bone marrow, blood, mesenteric lymph nodes and spleens were analysed by flow-cytometry and immunohistochemistry. All three cytostatic agents showed severe bone marrow depression. CP and MTX showed only mild reduction of cell populations in the spleen. CyPh showed a severe reduction of recirculating follicular B (RF-B) cells and marginal zone B (MZ-B) cells. At day 24 most populations were already recovered, but RF-B cells and MZ-B cells were still reduced. The reduction of the marginal zone and late recovery may imply that, beside the overall increased infection risk due to neutropenia, patients treated with chemotherapy are at risk for developing infections from encapsulated bacteria for a considerable period of time after treatment, extending beyond the period of bone marrow depression.

Association between the change in nutritional status in response to tube feeding and the occurrence of infections in children with a solid tumor

In 32 children with a solid tumor, the association between the change in weight for height, in response to 4 weeks of tube feeding during the intensive phase of treatment, and the occurrence of leukopenia, leukopenic infections, and nonleukopenic infections in a period thereafter (4-10 weeks) was studied. Factors possibly influencing the change in weight for height during the first 4 weeks of tube feeding were also assessed. A statistically significant negative correlation (rho = -0.59; p < .001) was found between the change in z-score of weight for height in response to the first 4 weeks of tube feeding, and the occurrence of nonleukopenic infections between 4 and 10 weeks. A reduced occurrence of nonleukopenic infections resulted in a significant reduction of the number of days of infection-related hospital admission (rho = .45; p = .009), which, besides providing advantages for the patient, also had economical benefits. The change in weight for height in response to tube feeding was mainly influenced by the incidence of therapy-induced vomiting (r = -.45; p = .02) and by the amount of energy provided by tube feeding (r = .47; p = .007). Based on these findings, it is recommended that naso-gastric tube feeding be used in children with a solid tumor during the early intensive phase of treatment, and that one should aim for a considerable increase in weight for height during the first 4 weeks of administration, since this has been shown to reduce the number of nonleukopenic infections in a subsequent period. The increase in weight for height may be improved by providing an optimal antiemetic protocol, which will increase energy uptake, and an energy-enriched formula, which will increase energy intake.

Treatment related deaths during induction and in first remission in acute lymphoblastic leukaemia: MRC UKALL X

The benefits of achieving a long term event free survival of 60-70% by using increasingly intense treatment regimens must be weighed against the increased risk of treatment toxicity. From 1985 to 1990, 1612 children with childhood acute lymphoblastic leukaemia (ALL) in the UK were treated on MRC UKALL X with intensive induction therapy, central nervous system directed therapy (cranial irradiation and intrathecal methotrexate), and continuing treatment for two years. There was a randomisation to receive blocks of additional intensification treatment at five weeks, 20 weeks, not at all, or both. The five year disease free survival was 71% for children randomised to two blocks of intensification, a 14% improvement on children randomised to no intensification treatment. Treatment related mortality in this national multicentre study has been analysed for induction and first remission (including those after intensification treatment). There were 38 induction deaths, 2.3% and 53 deaths in first remission, 3.3% (including those from a second malignancy). Thirty one (84%) of the induction deaths followed an infection: bacterial in 22 and fungal in nine. Thirty seven infective remission deaths occurred: bacterial in 11, viral in 16, fungal in seven, and three caused by Pneumocystis carinii pneumonia. Ten of these deaths followed a block of intensification treatment. The majority of noninfective remission deaths followed the development of a second tumour. Risk analysis for an induction death showed girls and children with Down's syndrome to be at greater risk. For deaths in first remission analysis showed an increased risk for bone marrow transplant (BMT) patients and children with Down's syndrome. There was no effect of age and leucocyte count for either group. Most significantly when BMT patients were excluded from the analysis, intensification treatment did not increase the risk of remission death.

Prospective evaluation of Candida antigen and antibody assays for detection of Candida infections in children with malignant disease

The clinical efficacy of assays for Candida albicans antigens by latex agglutination and for antibodies by indirect haemagglutination were prospectively evaluated in the diagnosis of invasive Candida infections in 38 children suffering from acute leukaemia or other malignant disease. The controls were 74 other patients without any malignancy; 72 of these had no signs or symptoms of fungal infections, but 2 had an invasive C. albicans infection. During a period of 21 months, 302 serum samples were tested by both assays, and the results were compared with clinical and other microbiological data. Invasive fungal infection was diagnosed on clinical grounds in 2 of the immunocompromised children, and periodic gut colonization was demonstrated in 11 of 36 (31%) children in this group. Positive Candida antigen was detected in 14 patients (37%) and a positive antibody titre in 7 patients (18%). Colonization was not correlated with antigen or antibody titre. Compared with the presence of invasive fungal infection, the antibody assay detected all four infections, whereas the antigen assay detected one of the two C. albicans septicaemias. Although the Candida antibody assay performed well, a detectable change in antibody titres appeared only slowly. Thus it was of no clinical help when antifungal treatment was to be considered. Follow-up of antibody titres, however, gave confirmation of the presence of fungal infection as well as the response to antifungal treatment.

Remission death in acute lymphoblastic leukaemia: a changing pattern

The pattern of remission deaths was examined in 842 children with acute lymphoblastic leukaemia (ALL) treated at a single centre over 18 years. The mortality rate from leukaemia fell significantly during three consecutive time periods during which treatment became progressively more intensive and that during remission induction fell from 3.5% to under 1%, but the rate of death in remission stayed constant at 5-6%. The factors associated with an increased risk of remission death were: young age, a higher leucocyte count, bone marrow transplantation, and Down's syndrome. The pattern of remission deaths changed over the years; measles and herpes viruses decreased while deaths associated with periods of intensification and gut toxicity increased. Four children developed second neoplasms. Treatment of ALL is still associated with a significant risk of death in remission but the pattern of infective deaths has changed. Many should be avoidable by provision of adequate supportive care, close supervision after periods of intensive treatment, and appropriate antibiotic, antifungal, and cytokine therapy.