Discordant Impact of HLA on Viral Replicative Capacity and Disease Progression in Pediatric and Adult HIV Infection.

HLA class I polymorphism has a major influence on adult HIV disease progression. An important mechanism mediating this effect is the impact on viral replicative capacity (VRC) of the escape mutations selected in response to HLA-restricted CD8+ T-cell responses. Factors that contribute to slow progression in pediatric HIV infection are less well understood. We here investigate the relationship between VRC and disease progression in pediatric infection, and the effect of HLA on VRC and on disease outcome in adult and pediatric infection. Studying a South African cohort of >350 ART-naïve, HIV-infected children and their mothers, we first observed that pediatric disease progression is significantly correlated with VRC. As expected, VRCs in mother-child pairs were strongly correlated (p = 0.004). The impact of the protective HLA alleles, HLA-B*57, HLA-B*58:01 and HLA-B*81:01, resulted in significantly lower VRCs in adults (p<0.0001), but not in children. Similarly, in adults, but not in children, VRCs were significantly higher in subjects expressing the disease-susceptible alleles HLA-B*18:01/45:01/58:02 (p = 0.007). Irrespective of the subject, VRCs were strongly correlated with the number of Gag CD8+ T-cell escape mutants driven by HLA-B*57/58:01/81:01 present in each virus (p = 0.0002). In contrast to the impact of VRC common to progression in adults and children, the HLA effects on disease outcome, that are substantial in adults, are small and statistically insignificant in infected children. These data further highlight the important role that VRC plays both in adult and pediatric progression, and demonstrate that HLA-independent factors, yet to be fully defined, are predominantly responsible for pediatric non-progression.

Vitamin D and tuberculosis: a multicenter study in children.

BACKGROUND: The aim of this study is to evaluate vitamin D levels in children with latent and active TB compared to healthy controls of the same age and ethnical background. METHODS: A multicenter observational study has been conducted in three tertiary care paediatric centres: Anna Meyer Children's University Hospital, Florence, Italy; Evelina London Children's Hospital, London, United Kingdom and Great Ormond Street Hospital, London, United Kingdom. Vitamin D was considered deficient if the serum level was <25 nmol/L, insufficient between 25 and 50 nmol/L and sufficient for a level >50 nmol/L. RESULTS: The study population included 996 children screened for TB, which have been tested for vitamin D. Forty-four children (4.4%) had active TB, 138 (13.9%) latent TB and 814 (81.7%) were controls. Our study confirmed a high prevalence of hypovitaminosis D in the study population. A multivariate analysis confirmed an increased risk of hypovitaminosis D in children with latent and active TB compared to controls [(P = 0.018; RR = 1.61; 95% CI: 1.086-2.388), (P < 0.0001; RR = 4.587; 95% CI:1.190-9.608)]. CONCLUSIONS: Hypovitaminosis D was significantly associated with TB infection in our study. Further studies are needed to evaluate a possible role of vitamin D in the treatment and prevention of tuberculosis in children.

Successful outcome of renal transplantation in a child with HIV-associated nephropathy.

Classical HIV-associated nephropathy (HIVAN) was first described before the advent of highly active antiretroviral therapy in late stages of HIV disease with high viral load and low CD4 cell count. Renal transplantation has been successful in a large series of carefully selected HIV-infected adults, with patient and renal allograft survival approaching those of non-HIV-infected patients. We report the successful outcome of living related renal transplantation in a vertically transmitted HIV-infected 8-year-old girl with end-stage kidney disease on haemodialysis due to HIVAN. The pretransplant preparations and post-transplant care, with particular emphasis on immunosuppression and avoidance of opportunistic infections, are discussed.

Polyarticular septic arthritis in an 11-year-old child.

A child with polyarthritis is always a diagnostic challenge for the treating physician. Polyarthritis can be a clinical manifestation of diverse disease processes, and the differential diagnosis is understandably very broad. We present a case of polyarticular septic arthritis, which is osteomyelitis complicated, caused by Streptococcus pyogenes identified by 16S polymerase chain reaction (PCR) in a healthy child, with previous synovial fluid cultures negative. This case underlines the importance of early aggressive therapy and the role of PCR/16S ribosomal bacterial DNA amplification to detect the causative microorganisms in septic arthritis when cultures remain negative.

Diagnostic features of community-acquired pneumonia in children: what's new?

AIM: To critically summarise the available data on diagnosis of CAP in children, focusing on the newest findings and on the need for new studies. METHODS: Eighty studies on the diagnosis of paediatric community-acquired pneumonia were scrutinised. RESULTS: We found no significant associations between the signs or symptoms and aetiology of pneumonia and concluded that chest radiographs remain controversial and real-time polymerase chain reaction appears more sensitive than blood cultures. CONCLUSION: Antibiotic overuse could make it difficult to differentiate viral and bacterial causes. Molecular methods provide promising tools for diagnosing infection by atypical bacteria, but are expensive and should be used selectively.

Spinal tuberculosis in children.

OBJECTIVES: To review our experience of spinal tuberculosis (TB) at a major UK paediatric tertiary referral centre. METHODS: The authors performed a retrospective case survey of 21 patients admitted to Great Ormond Street Hospital over a 15-year period (1995-2010) with confirmed or presumed spinal TB. Data were collected concerning demographics, clinical, laboratory and radiological characteristics, treatment and clinical outcome. RESULTS: Only one patient was of Caucasian origin. Four (19%) had a previous diagnosis of TB, 11 (52%) a known contact, 10 (48%) had received BCG vaccine and none were HIV-positive. Clinical presentations included systemic symptoms (18 patients), back pain (16 patients), deformity (five patients) and neurological deficits (12 patients). Mycobacterium tuberculosis was isolated from 14 patients (67%) including one multi-drug resistant strain. Spinal cord compression or critical stenosis was demonstrated in eight patients (38%). All received TB treatment for at least 12 months; six patients received treatment for a longer period. Seven (33%) underwent surgical intervention. Seventy-five per cent showed clinical and radiological resolution after treatment. No patients died or suffered long-term neurological deficit. CONCLUSIONS: Spinal TB in children needs a high index of suspicion for diagnosis. Early referral to an expert centre allows a multidisciplinary approach to management. The authors recommend that treatment should be individually tailored and may need to exceed 12 months in cases of poor adherence, extensive disease or drug resistance.

Skull base osteomyelitis and potential cerebrovascular complications in children.

Skull base osteomyelitis is an aggressive, life-threatening infection that can be challenging to diagnose and treat. It occurs predominantly in elderly immunocompromised patients, but it has also been reported in children with normal immunological status. Typical skul base osteomyelitis arises as a complication to ear infection mainly involving the temporal bone and is usually caused by Pseudomonas aeruginosa. Atypical or central skul base osteomyelitis originates from paranasal infections, is primarily centred on the clivus and is usually caused by Aspergillus, Pseudomonas, Salmonella or Staphylococcus species. Potential complications include retropharyngeal abscesses, cranial neuropathies, meningitis, intracranial abscesses, sinovenous thrombosis, and carotid artery involvement with or without ischemic infarcts. The purpose of this pictorial essay is to illustrate the spectrum of imaging findings and potential complications of skul base osteomyelitis.

Kikuchi-Fujimoto disease causing fever of unknown origin in a nine-year-old boy.

We describe a case of fever of unknown origin (FUO) in a 9-y-old boy finally diagnosed with Kikuchi-Fujimoto disease (KFD) and discuss the implications for the management of FUO in children. KFD should be considered in the differential diagnosis of patients presenting with FUO to prevent misdiagnosis and inappropriate treatment.

Postinfectious purpura fulminans secondary to varicella-induced protein S deficiency.

Varicella is usually a benign and self-limited disease of infancy and childhood although it has been recognized that it sometimes has severe and life-threatening complications. We report a case of postinfectious purpura fulminans with acquired protein S deficiency following varicella in a 6-year-old child and discuss the underlying mechanism of postinfectious purpura fulminans.

The likelihood of an indeterminate test result from a whole-blood interferon-gamma release assay for the diagnosis of Mycobacterium tuberculosis infection in children correlates with age and immune status.

BACKGROUND: Interferon-gamma release assays for the diagnosis of infection with Mycobacterium tuberculosis have been increasingly used in recent years and are endorsed by national guidelines, but experience regarding their use in children is still limited. METHODS: We retrospectively evaluated the routine use of the QuantiFERON-TB Gold In-Tube assay (QFT-IT) in a pediatric tertiary care center with a high prevalence of immunocompromising conditions. The relationship between age, immune status, and likelihood of an indeterminate test result was analyzed using logistic regression analysis and fractional polynomials. RESULTS: Two hundred thirty-seven tests from 237 children were included in the analysis. Fifty-nine children (25%) were immunocompromised by our definition. An indeterminate test result was obtained in 83 children (35%). The likelihood of an indeterminate test result was inversely correlated with age (P < 0.001) for children who were not known to be immunocompromised, and decreased by 13% per year of age. Impaired immunity (P < 0.001) was independently associated with a higher probability of an indeterminate QFT-IT. Among 161 children with a documented tuberculin skin test, 89% had a concordant QFT-IT (kappa = 0.71). Twelve of 16 patients with culture-proven TB had a positive QFT-IT. CONCLUSION: These data suggest that QFT-IT may not provide a determinate test result in a substantial proportion of children in a tertiary care setting due to the combination of young age and primary and acquired immune deficiencies.

Hemophagocytic lymphohistiocytosis associated with Epstein Barr virus and Leishmania donovani coinfection in a child from Cyprus.

We present a case of a 9-month-old girl from Cyprus with hemophagocytic lymphohistiocytosis associated with Epstein Barr virus and Leishmania donovani coinfection. Treatment with liposomal amphotericin B resulted in a dramatic resolution of clinical and laboratory abnormalities. To our knowledge, this is the first reported case of a coinfection-associated hemophagocytic lymphohistiocytosis and the first clinical report of visceral leishmaniasis infection in Europe by L. donovani.

The conundrum of prior bacille calmette-guerin vaccination in children of temporary residents in the United States.

Bacille Calmette-Guerin (BCG) is one of the most widely used vaccines throughout the world. Children of temporary residents in the United States frequently undergo tuberculin skin testing as part of their health maintenance visits. Management of those children with a positive skin test can lead to doctor-parent disagreements, because of differences in tuberculosis (TB) policies between the United States and other countries that routinely administer BCG vaccine. Two British specialists compare their approach with that of the United States. They also discuss the potential for specific diagnosis of latent TB infection with interferon-based TB diagnostic blood testing, to distinguish positive skin tests caused solely by BCG vaccination.

Morbidity, mortality, and response to treatment by children in the United Kingdom and Ireland with perinatally acquired HIV infection during 1996-2006: planning for teenage and adult care.

BACKGROUND: Recent evidence suggests that decreases in morbidity and mortality in cohorts of adults infected with human immunodeficiency virus (HIV) are showing signs of reversal. We describe changes over time in these characteristics and in the response to treatment among children in the United Kingdom and Ireland with perinatally acquired HIV infection, many of whom are now adolescents. METHODS: We analyzed prospective cohort data reported to the National Study of HIV in Pregnancy and Childhood (NSHPC) and the Collaborative HIV Paediatric Study. RESULTS: By mid 2006, 1441 HIV-infected children were reported to NSHPC; 40% were > or = 10 years old at their most recent follow-up visit, and 34% were receiving care outside London. The proportion of children born abroad increased from 24% during 1994-1996 to 64% during 2003-2006. The percentage of total child time during which children received highly active antiretroviral therapy (HAART) increased from 36% during 1997-1999 to 61% during 2000-2002 and 63% during 2003-2006. Of children who were naive to antiretroviral therapy at the start of HAART, the percentage with an HIV-1 RNA load of < 400 copies/mL after 12 months increased from 52% during 1997-1999 to 79% during 2003-2006. In multivariate analysis, only calendar time predicted virological response, whereas both younger age and lower CD4 cell percentage at HAART initiation predicted increases of > 10% in the CD4 cell percentage. A total of 31% of children aged 5-14 years and 38% aged > or = 15 years at their most recent follow-up visit had been exposed to drugs from each of the 3 main HAART classes. The rate of AIDS and mortality combined decreased from 13.3 cases per 100 person-years before 1997 to 3.1 and 2.5 cases per 100 person-years, respectively, during 2000-2002 and 2003-2006; rates of hospital admission also declined during this interval. Of 18 children known to have died since 2003, 9 died within 1 month after presentation. CONCLUSIONS: Morbidity and mortality rates among HIV-infected children continue to decrease over time. Because these children are increasingly dispersed outside London, specialist care is now provided in national clinical networks. Transition pathways to adolescent and adult services and long-term observation to monitor the effects of prolonged exposure to both HIV and HAART are required.

Differential selection pressure exerted on HIV by CTL targeting identical epitopes but restricted by distinct HLA alleles from the same HLA supertype.

HLA diversity is seen as a major challenge to CTL vaccines against HIV. One current approach focuses on "promiscuous" epitopes, presented by multiple HLA alleles from within the same HLA supertype. However, the effectiveness of such supertype vaccines depends upon the functional equivalence of CTL targeting a particular epitope, irrespective of the restricting HLA. In this study, we describe the promiscuous HIV-specific CTL epitopes presented by alleles within the B7 supertype. Substantial differences were observed in the ability of CTL to select for escape mutation when targeting the same epitope but restricted by different HLA. This observation was common to all six promiscuous B7 epitopes identified. Moreover, with one exception, there were no significant differences in the frequency, magnitude, or immunodominance of the CTL responses restricted by different HLA alleles to explain these discrepancies. This suggests that the unique peptide/MHC complexes generated by even closely related HLA induce CTL responses that are qualitatively different. This hypothesis is supported by additional differences observed between CTL targeting identical epitopes but restricted by different HLA: first, the occurrence of distinct, HLA-specific escape mutation; second, the recruitment of distinct TCR repertoires by particular peptide/MHC complexes; and, third, significant differences in the functional avidity of CTL. Taken together, these data indicate that significant functional differences exist between CTL targeting identical epitopes but restricted by different, albeit closely related HLA. These findings are of relevance to vaccine approaches that seek to exploit HLA supertypes to overcome the problem of HLA diversity.

Mannose-binding lectin in susceptibility and progression of HIV-1 infection in children.

BACKGROUND: Mannose-binding lectin (MBL; encoded by MBL-2) is a circulating pattern-recognition molecule that recognizes microbial carbohydrate motifs, leading to complement activation and cell lysis. Mutations in the MBL-2 promoter and of the MBL-2 gene exon 1 result in reduced protein levels and increased susceptibility to infection. We have investigated the effect of MBL-2 polymorphisms on susceptibility and progression of HIV-1 infection in children. PATIENTS AND METHODS: One-hundred and twenty-eight children, aged 2-16 years were recruited. MBL-2 genotypes were determined by PCR and heteroduplex analyses. Serum MBL levels were measured by ELISA. Comparison of genotypes (A=wild type, O=variant alleles) and protein levels between groups was performed using chi-squared, Mann-Whitney U or Kruskal-Wallis tests. RESULTS: Children were classified according to the Centers for Disease Control and Prevention clinical classification: A, B or C (mildly symptomatic [n=39], moderately symptomatic [n=58] or severely symptomatic AIDS [n=31]) or immune category 1 (n=77), 2 (n=46) or 3 (n=5). Analysis of MBL-2 genotypes with respect to clinical classification yielded minimal differences. However, patients in immunological categories 2 and 3 (<25% CD4+ T cells) were more likely to have MBL-2 variant alleles (P=0.01). We further explored MBL status with respect to disease progression. Only 1/10 long-term non-progressors (LTNPs) had an MBL-2 mutation (A/D) with a corresponding protein level of 611 ng/ml. CONCLUSIONS: MBL deficiency was more frequent in patients with severe disease as assessed by CD4+ T-cell status. MBL-2 variants may be less frequent in children classified as LTNPs. MBL analysis could be useful in identifying children with slow disease progression and, consequently, may not require immediate antiretroviral treatement.

Adherence and acceptability of once daily Lamivudine and abacavir in human immunodeficiency virus type-1 infected children.

BACKGROUND: Data on adherence to and acceptability of once daily lamivudine and abacavir are few. METHODS: Twenty-four U.K. human immunodeficiency virus type-1 infected children 2-13 years of age participated in the Pediatric European Network for the Treatment of AIDS (PENTA) 13 single arm, open label pharmacokinetic study of twice (every 12 hours) versus once (every 24 hours) daily lamivudine and abacavir. Caregivers were asked to complete an adherence questionnaire at screening, week 0 (switch once daily to twice daily) and weeks 4, 12 and 24. Acceptability was also assessed at screening and week 24. RESULTS: Fifteen children were taking lamivudine and abacavir as part of their regimens, 8 lamivudine only and 1 abacavir only. After switching to lamivudine/abacavir every 24 hours, 7 (29%) received once daily regimens for all drugs. Twenty-three (96%) caregivers thought that switching to once daily lamivudine/abacavir would make things a lot/a little easier for their child: 17 (71%) thought it was actually easier after switching. Six mothers with children taking a mixture of twice/once daily drugs changed their mind, whereas all mothers of children on once daily regimens agreed that it was a lot easier. Nonadherence (missing doses in the last 3 days) was reported for 8 of 118 (7%) completed questionnaires; missed doses were reported for every drug in the regimen with reasons such as "not at home," "forgot" or "routine different from normal." However, viral loads in all these children remained <100 copies/mL. CONCLUSION: Adherence to once daily abacavir/lamivudine was good with no evidence of an association between nonadherence and virologic rebound. Acceptability of once daily drugs was best when the whole regimen was dosed once daily.