Introduction
BCG vaccination administered at birth or shortly after birth is included in vaccination schedules in countries with a high prevalence of tuberculosis (TB). At present, three different BCG vaccine substrains, Danish 1331, Tokyo 172–1, and Russian BCG-I, are recommended by the World Health Organization (WHO) as International Reference Reagents (IRR). These three substrains constitute the major proportion of BCG vaccine production worldwide as they are supplied by the United Nations Children’s Fund (UNICEF) [
1‐
3]. An additional substrain, Moreau-RJ, was approved as a WHO IRR by the WHO Expert Committee on Biological Standardization meeting in 2012 [
1,
2]. In general, the majority of locally produced BCG vaccine substrains have not been well-characterized. In terms of efficacy, no BCG substrain was found markedly superior to other strains and there is no global consensus on the choice of an optimal BCG substrain for general use [
3‐
5].
Differences in reactogenicity between vaccines can be observed, and they relate to particular substrains. In 1955, the highly reactogenic BCG Danish vaccine was replaced in Poland by the locally produced BCG Moreau vaccine, a descendant of Brazilian BCG Moreau substrain. The BCG Danish 1331 vaccine and the Pasteur substrains have generally been considered reactogenic [
6‐
10]. The mean risk of osteitis following BCG vaccination varies from country to country, with some reports indicating low incidence (e.g., 0.02 per million in Japan) and some presenting it as high (e.g., 1000 per million in Sweden and Finland) [
5,
7‐
9]. In 1971, a dramatic rise in the incidence of osteitis observed in Sweden and Finland coincided with the replacement of the Gothenburg substrain of the BCG vaccine produced by the Swedish BCG Laboratory, based on the same Danish 1331 substrain [
8]. In 1978, it was replaced by the BCG Glaxo substrain, which caused lower incidence of BCG osteitis in Finland and in Britain [
6‐
8].
On the basis of the results obtained by Zapaśnik-Kobierska and Stopnicka, lymphadenitis complications in newborns vaccinated with BCG Moreau, BCG Danish 1331, or BCG Pasteur in the vaccinated cohort were found to stand at 0.3%, 2.4%, and 4.9%, respectively [
11]. Furthermore, trials performed in Poland in 1972 revealed that the BCG Pasteur vaccine produced by the Lublin manufacturer was less reactogenic than that originally produced in France (18.6% versus 28.4%) [
10]. Compared with the Pasteur substrains, the Tokyo and Moreau substrains are rarely associated with a high incidence of adverse events [
5,
9,
10]. A recently published randomized clinical trial of a BCG vaccine produced with the Danish substrain 1331 SSI showed a higher incidence of lymphadenitis than expected, with a regional lymphadenitis rate of 6.1 per 1000 vaccinated [
12]. Lymphadenitis following immunization with the BCG Moreau vaccine in Poland in the years 1994–2000 was estimated to be 0.2 per 1000 vaccinated. It was reported that the incidence rate of suppurative lymphadenitis in Poland was lower in comparison with other countries [
13].
The frequency of fatal BCG disseminated infection is estimated at approximately 0.06–1.56 cases per million doses of vaccine administered, typically in primary immunodeficiency disease (PID) [
14‐
34]. The majority of BCG disseminated infections have been reported in the literature in patients highly susceptible to mycobacterial diseases, well-defined SCID patients and those with Mendelian susceptibility to mycobacterial diseases (MSMD) [
15‐
27]. The fatal outcome of BCG disseminated infection has also been reported in other PID less prone to BCG infection, such as chronic granulomatous diseases (CGD), hyper-IgE syndrome (HIES), X-linked hyper IGM syndrome (HIGM), nuclear factor (NF)-κB essential modifier (Nemo), and GATA2 deficiency [
15,
18,
21,
22,
27‐
29]. One of the biggest groups of PID patients with BCG disseminated infection was retrospectively analyzed by Casanova et al. [
14‐
16]. A multicenter, retrospective study comprising the data obtained from 28 centers in 17 different countries has recently been published by Marciano et al. This is the largest study published to date, involving 349 SCID patients vaccinated with BCG vaccine during the first months of life [
35].
The aim of the present study was to estimate the frequency of complications and the risk associated with BCG vaccination in SCID patients hospitalized in the Department of Immunology, CMHI in Warsaw, over the period of 35 years, and to compare the results with those described in the retrospective study of SCID patients vaccinated with a variety of BCG vaccines containing different substrains used worldwide [
35].
Material and Methods
As many as 1727 patients were diagnosed with PID in the Department of Immunology, CMHI, Warsaw, between 1980 and 2015. A total of 52 Caucasian origin SCID patients, born in Central-Eastern Poland, were vaccinated with BCG at birth. The incidence of BCG-associated infections following vaccination with the BCG Moreau vaccine produced by Biomed, Lublin, Poland, was analyzed in a group of SCID patients susceptible to BCG infection. BCG disseminated infections were diagnosed based on clinical, microbiological, and histopathological findings following ESID diagnostic criteria [
19] (
https://esid.org/Working-Parties/Registry-Working-Party/Diagnosis-criteria). Localized BCG infection was referred to as a lesion inside the inoculation site (> 10 mm) and/or lymphadenitis limited to the region of the inoculation site while disseminated BCG infection was defined as a persistent process spreading over two or more regions beyond the inoculation site. The
Mycobacterium tuberculosis complex molecular analysis was conducted using the PCR (MTD Gen-Probe) test and the analysis of
mycobacterium culture was performed in a BACTEC 460 Tb or MGIT 960 system. Mutation analysis in PID patients was performed at the Department of Immunology, Erasmus MC in Rotterdam, Netherlands, in the Center for the Study of Primary Immunodeficiencies, Assistance Publique, Hopitaux de Paris, Necker Hospital, 75,015 Paris, France. Absolute numbers and percentages of circulating B and T subsets CD19/CD20, CD3, and natural killer cells (NK-CD56/CD16) were assessed and compared with reference values established in age-matched groups of healthy children [
36]. Statistical analyses were performed using STATISTICA v 10.0 and Microsoft Excel v 2007. Quantitative variables were characterized by the arithmetic mean of standard deviation or median or max/min. Qualitative variables were presented as counts and percentages. In order to check if a quantitative variable derived from the population of normal distribution, the Shapiro-Wilk test was used. Statistical significance of differences between groups (unpaired variables model) was processed with the Student
t test or Mann-Whitney
U test. The Chi-squared test and Fisher’s exact test for independence was used for qualitative variables. In order to determine dependence, strength and direction between variables, correlation analysis was used by determining the Pearson or Spearman’s correlation coefficients. In all calculations, the statistical significance level of
p = 0.05 was used. The statistical analysis of the retrospective study of 52 SCID patients hospitalized at CMHI was compared with that of 349 SCID patients investigated by Beatriz E. Marciano and co-authors [
35].
Ethics Statement
This study was approved by the Bioethics Committee of CMHI—resolution no 51/KBE/2017, 06 September 2017.
Results
In 52 SCID patients diagnosed in CMHI, the mean age at which first SCID symptoms occurred was 3.3 months (in the range of 1.0–24.0), the age of SCID diagnosis was 13.5 months (in the range of 1.0–63.0). In 19 out of 52 cases, the diagnosis with SCID was carried out at the age of 7–12 months, which was comparable with 94 patients (p = 0.1510) from the Marciano study.
Disseminated BCG infection occurred in 10 SCID patients out of 52 vaccinated with BCG, twelve localized complications were present in both group, separately or together with disseminated BCG infection. (Table S1). Disseminated BCG infection was diagnosed in 10 SCID patients with TB+NK-phenotype, in 6 with IL2RG mutation, in one patient with JAK3 deficiency and in 3 with unknown mutations. Disseminated BCG infection was not present in the group of TB-NK+SCID patients, including 16 patients with RAG1/2, 2 patients with IL7RA and 2 with Artemis mutation, 1 patient each with MHC II, ZAP-70, and Cernunnos, and in 10 patients with unknown mutations (Table S1). Among SCID patients, the clinical manifestation of disseminated BCG infection was recognized as meningitis in 1 patient, bronchopneumonia in 4, disseminated skin infection in 3, single skin abscess in 2, and osteomyelitis and/or pathological fractures occurred in 6 patients. Infiltrations in spleen and liver abscess were observed in 5 patients. No brain abscess, lymphadenitis, and other localization of BCG infection were observed. The infection was confirmed with the positive polymerase chain reaction (PCR) for the
Mycobacterium tuberculosis complex and culture in 8 out of 10 patients. Following the diagnostic criteria for disseminated BCG infection, possible diagnosis of disseminated BCG infection was established in two patients with clinical symptoms and typical histopathologic changes with granulomas formation diagnosis [
19] (
https://esid.org/Working-Parties/Registry-Working-Party/Diagnosis-criteria). In three infants, SCID diagnosis was established before 1985, when they were admitted in the terminal stage to the intensive care unit. Two of them died soon in the course of multiple organs insufficiency, postmortem examination found granulomas, which is the full field diagnosis criteria of possible form of disseminated BCG infection [
19] (
https://esid.org/Working-Parties/Registry-Working-Party/Diagnosis-criteria). The third one, with a positive family history (death of 5 infants, boys) was admitted because of respiratory insufficiency and hepatosplenomegaly. Bronchopulmonary lavage samples were tested for
Mycobacterium tuberculosis complex; positive PCR and culture results led to the diagnosis as a definitive form of the disease [
19] (
https://esid.org/Working-Parties/Registry-Working-Party/Diagnosis-criteria). He died after 4 months, despite the administration of 5 anti-TB medications in a course of overwhelming BCG infection. The HSCT procedure was not considered because of serious condition of this child.
Disseminated BCG infections in 10 (19%) SCID patients hospitalized at CMHI constitute a significantly lower score in comparison with 119 (34%) in the Marciano study (p = 0.0028). However, in 12 (24%) SCID patients with localized BCG, the rate was higher, but not significantly, compared with the Marciano study’s 60 (17%) (p = 0.2417). Mortality caused by BCG-associated complications in the Marciano cohort of SCID patients was higher, but not significantly: 46 (13%) deaths out of 349 (p = 0.1724). In the CMHI cohort, 3 (5%) deaths occurred before 1985.
The median absolute number of T cells at the time of SCID diagnosis in patients with disseminated BCG-associated complications was found to be insignificant (p = 0.0915), while the absolute number of B cells was significantly higher (p = 0.0126) and the number of NK cells was significantly lower (p = 0.0161) in the group with BCG complications in the CMHI study (Table S2).
Disseminated BCG-associated complications in the CMHI study were found only in 18 out of 52 SCID patients with a low number of NK cells (p < 0.000001), localized complications were observed in both groups; insignificantly higher in NK+SCID patients (p = 0.4859) (Table S3).
Dual drug anti-TB therapy (isoniazid and rifampicin) was administered to 17 patients (33%) with local BCG complications. In 7 out of 10 SCID patients, BCG disseminated infection was successfully treated in all of them with 4 or 5 anti-TB drugs (isoniazid, rifampicin, ethambutol, ciprofloxacin, and aminoglycoside). In our study, the mean age at HSCT was 21.4 m. (a range of 4.0–96.0 m.). HSCT was administered in 43 patients (83%) in total vs 190 (54%) SCID patients in the Marciano study, the number being significantly higher in the CMHI study (
p = 0.0001). Fifty-eight out of 349 SCID patients were diagnosed in Brazil, constitute the largest cohort of this study [
35]. Similarly, fewer HSCT procedures were performed in SCID patients in Brazil, in 24 (46%) than at CMIH, in 43 (83%) (
p = 0.0001). Polish and Brazilian cohorts were vaccinated at birth with a locally produced BCG Moreau vaccine [
18,
19,
35].
In 7 SCID patients with BCG disseminated infection HSCT procedure was introduced: in 1 an unconditioned transplant from the matched related brother was done, in 4 patients HSCT from no HLA-matched related donor was performed, in 2 -HSCT from HLA-matched unrelated donor was done. In all 6 patients reduced-intensity conditioning was used, partial ablation with chemotherapy, serotherapy, antithymocyte globulin. This conditioning regimen prevented graft rejection and graft versus host disease (GVHD) with a satisfying stem cell engraftment, in one patient transient, moderate course of this disease was observed. Mixed chimerism concerning various cell lines was observed in 4 infants and is still present in one. Antimycobacterial treatment was discontinued within 8–15 months in all 7 treated patients, which coincided with immunological reconstitution. In 2 post-HSCT patients local and disseminated reactivation of BCG occurred within 3 months after transplantation. One of the patients was treated with 2 anti-TB drugs because of local BCG infection. He began to lose weight and a subfebrile condition developed. Infiltrations in spleen, liver, pathological fracture of the right hand third and fourth finger distal bones and disseminated skin abscess appeared. During the next 15 months, clinical improvement and full chimerism occurred. In the other patients with local BCG infection following HSCT, treatment with 2 anti-TB drugs was discontinued within the next few weeks. Enlargement and infiltration in the occultation site was observed and slowly dispersed during the 8 months of therapy with 3 anti-TB drugs.
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