Adolescent Tuberculosis: 6 Years of Experience in a Tertiary Care Pediatric Hospital in Buenos Aires, Argentina

INTRODUCTION

Adolescence is a key risk period for tuberculosis disease and its adverse outcomes. This group commonly develops infectious forms of tuberculosis and has a wider range of social contacts outside the household. There are few specific data on the behavior of tuberculosis disease in this population.

METHODS

A total of 292 patients 10-19 years of age with tuberculosis between January 2016 and December 2021 were retrospectively analyzed in the Department of Phthisiology of the Children's Hospital "Dr. Ricardo Gutiérrez" of Buenos Aires, Argentina.

RESULTS

The median patient age was 14 years (interquartile range 12-16). Most patients were previously healthy, and 55% were unaware of the source of the infection. However, 75% sought medical advice owing to the presence of symptoms, with hemoptysis and weight loss being most frequent in those older than 15 years. Lung imaging findings consistent with severe disease were significantly associated with an age of >15 years. Respiratory cultures were positive in 62% of the samples obtained. Half of the patients required hospitalization, while 45% showed extrapulmonary involvement. Evolution was as follows: 74% recovered from the illness, 13% were lost to follow-up, 11% were referred to a less complex facility, 1% experienced treatment failure, and 3 (1%) patients died. Pulmonary cavities and positive bacilloscopy were associated with the presence of pulmonary sequelae at the end of treatment.

CONCLUSIONS

Tuberculosis in adolescents, particularly in those >15 years of age, may present characteristics similar to those of adults, with a higher frequency of severe pulmonary disease leading to pulmonary sequelae.

Epidemiological and clinical features of the 2016-2018 Zika virus outbreak in northern Argentina

BACKGROUND

During the American epidemic, Zika virus (ZIKV) expanded rapidly through dengue virus (DENV)-endemic regions. We analyzed the presentation of ZIKV infection in patients from the City of Orán, Argentina, and compared some of its features with dengue presentation in the same region.

METHODS

A retrospective study was conducted at San Vicente de Paul Hospital during 2016-2018. Clinical and demographic characteristics, pre-existing immunity to DENV, viral load and type I interferon (IFN) responses were studied in 63 patients with ZIKV infection.

RESULTS

Clinical manifestations of ZIKV infection were generally mild compared with dengue, although rash (p<0.001) and itching (p<0.001) were significantly more prevalent in ZIKV patients. ZIKV patients aged <15 y manifested relatively mild disease compared with older ZIKV patients, showing a decreased prevalence of headache (p=0.008), retro-orbital pain (p=0.001) and arthralgia (p=0.001). Increased Zika incidence was observed in female patients (60.3%). Serum viral load was low to undetectable in ZIKV patients and was not associated with serum anti-DENV IgG titers. Interferon-α and IFN-β serum levels did not correlate with serum viral load in ZIKV patients.

CONCLUSIONS

Clinical presentation of ZIKV and DENV infections is largely overlapping, presenting a challenge for diagnosis and risk assessment for uniquely at-risk populations.

1357. Collateral consequence of COVID pandemic: Increased incidence of cat scratch disease

Background

Cat scratch disease (CSD) is a zoonosis caused primarily by Bartonella henselae.

The aim of our study was to determine the incidence CSD before the preventive and obligatory social isolation/distancing that was indicated in Argentina as a consequence of the SARS-CoV-2 pandemic on March 19, 2020 ("first period") and to compare it with the incidence since then to present ("second period").

Methods

Retrospective analysis of patients with CSD admitted to the Infectious Diseases outpatient office at Ricardo Gutiérrez Children’s Hospital (a tertiary care center) from March 2012 to March 2022. Charts were reviewed for demographic and epidemiological data, duration of symptoms, clinical manifestations and systemic compromise.

Results

Two hundred twenty-nine patients were observed during the study period. The median delay between symptoms onset and medical consultation was 15 days (IQR 9-30d), without statistically significant differences between periods The median age at presentation was 101.67 months (range 11.3 to 211.87 months) Age and gender were similar between periods.

The average number of cases per month was 1.63 (158 in 97 months) versus 3.23 (71 cases in 22 months) in the first and second periods, respectively, with an increasing incidence of 98%. The frequency of systemic compromise was higher in the second period: 47.89% versus 32.28% (p= 0.01).

The months with the highest incidence were February to July.

Conclusion

A significant increase of CSD were observed during the COVID pandemic probably related to a closer children´s contact with pets due to the strict quarantine that health authorities implemented. Moreover, an unexpected finding was a higher proportion of patients with systemic CSD during the pandemic period.

Disclosures

All Authors: No reported disclosures.

2157. Low Interferon-γ and Interleukin-13 Levels in the Respiratory Tract are Related to Life-threatening Respiratory Syncytial Virus Infection in Previously Healthy Infants

Background

The mechanisms of interindividual susceptibility to respiratory syncytial virus (RSV) are not clearly understood. Viral load (VL), an exaggerated immune response or T-helper 2 (Th2) bias were postulated as playing a role in the severity of RSV infection. We aimed to analyze VL, cytokine profiles and their association with life-threatening disease (LTD).

Methods

Prospective cohort study including previously healthy full-term infants &lt; 12 months old, hospitalized with a first RSV infection in 2017-2019. Nasopharyngeal aspirates were performed on admission to assess VL (by qRT-PCR) and cytokines levels (using a Bioplex panel). Cytokines were grouped according to their functional classification: proinflammatory (TNF-α), regulatory (interleukin [IL]-10), Th1 (interfereron-γ [IFN-γ]), Th2 (IL-4, IL-5, IL-9, IL-13) and Th17 (IL-17a). Patients were defined to have LTD when required admittance to the intensive care units and ventilatory support.

Results

One hundred and nineteen patients were studied, 68 (57%) were male; median age was 3 months. Nineteen (16%) infants developed LTD, with no significant differences in socioeconomic, pregnancy and infant variables compared with other RSV cases. Virus subtypes were not related to LTD (p= 0.77). VL was not associated with LTD (p= 0.51). Patients with LTD had significantly lower levels of IFN-γ (mean 0.08 pg/ml [standard deviation -SD- 0.06] vs. 0.32 pg/ml [SD 0.4]; p= 0.001) and IL-13 (mean 0.03 pg/ml [SD 0.04] vs. 0.05 pg/ml [SD 0.07]; p= 0.02), fig 1. IFN-γ and IL-13 inversely correlated with days of hypoxemia (p&lt; 0.001 and p= 0.002, respectively). VL, IFN-γ and IL-13 did not correlate with duration of symptoms before admission. No relationship was observed between IFN-γ, IL-13 and age, sex or breastfeeding. In 102 (86%) samples, IL-4 was under the limit of quantitation. TNF-α, IL-5, IL-9, IL-10 e IL-17a were not related to LTD.

IFN-γ and interleukin-13 levels according to clinical outcome.

Conclusion

To our knowledge, this is the first study to relate low IL-13 levels to LTD in previously healthy infants. Patients with LTD had 4-fold lower levels of IFN-γ. The severity of RSV infection may be the result of a deficient immune response rather than a higher viral load or an overactive immune response. These findings provide additional evidence for the development of preventive and therapeutic strategies.

Disclosures

All Authors: No reported disclosures.

487. Analysis of the Association between Specific Antibody Response against Respiratory Syncytial Virus Fusion Protein Conformations and Life-Threatening Infection in Previously Healthy Infants

Background

Specific humoral response against pre-fusion (pre-F) conformation of respiratory syncytial virus (RSV) F protein has been proposed to play a role against severe infection. We aimed to analyze the association between serum IgG titers against pre-F and post-fusion (post-F) conformations of RSV F protein and life-threatening RSV disease (LTD) in previously healthy infants.

Methods

Prospective cohort study including previously healthy infants &lt; 12 months, hospitalized with a first RSV infection, in 2017-2019. Patients were defined to have LTD when required intensive care and ventilatory support. Pre-F exclusive and post-F-specific antibody responses were determined by post-F competition and non-competitive immunoassays, respectively, and neutralizing activity was measured by plaque reduction neutralization test. Viral load (VL) was assessed by qRT-PCR from nasopharyngeal aspirates collected on admission. Serum samples were collected within 72 h from admission and in convalescence (between 14 to 60 days).

Results

Seventy-five patients were included, median age 3 months, 60% (n=45) were males; 21 patients developed LTD. Importantly, acute and convalescent post-F and pre-F exclusive IgG titers did not associate with LTD (Fig 1). There was a positive correlation between neutralizing antibody titers and pre-F exclusive IgG titers (p=0.016). Post-F and pre-F exclusive IgG titers negatively correlated with age in acute phase (p&lt; 0.0001 and p= 0.0009). In acute phase, post-F and pre-F exclusive IgG titers were higher in patients ≤ 2 months (Fig 2). Patients &gt; 2 months increased post-F and pre-F exclusive IgG titers in convalescence. Additionally, post-F and pre-F exclusive titers did not correlate with VL, and VL was not related to LTD.

Conclusion

-Pre-F exclusive and post-F IgG titers did not associate with LTD, even though pre-F exclusive IgG correlated with neutralizing antibody titers.

-Infants under two months of age developed a lower humoral response, likely due to an interference by maternal antibodies and/or immunological immaturity.

-These findings highlight the importance of fully characterizing the immune response against RSV and its association with disease severity for the development of preventive strategies.

Disclosures

Barney S. Graham, MD, PhD, BSG: BSG is an inventor on patents for the stabilization of the RSV F protein (WO2014160463A1, Prefusion RSV F proteins and their use).|National Institutes of Health: Inventor on patents for RSV vaccines|National Institutes of Health: inventor on patents for measles and other paramyxovirus vaccines.

[Exogenous Cushing syndrome due to drug interaction of ritonavir and inhaled fluticasone. Report of three pediatric cases]

The increase in life expectancy with the advent of highly effective antiretroviral therapy poses challenges in terms of toxicity and drug interactions. Exogenous Cushing syndrome by interaction between ritonavir and inhaled fluticasone in children diagnosed with human immunodeficiency virus infection and chronic pulmonary pathology is rare. So far, there are 20 cases reported. Three pediatric cases are reported, with a diagnosis of human immunodeficiency virus infection and chronic pulmonary pathology who presented exogenous Cushing syndrome with inhaled fluticasone at usual doses due to drug interaction between it and ritonavir. The patients resolved the clinical picture after 2-4 months of fluticasone suspension and remain asymptomatic in the follow-up.

[Pediatric pyomyositis: Experience in a Pediatric Reference Center in Argentina]

BACKGROUND

Pyomyositis is the infection of skeletal muscle, a rare pathology in children. Aim To describe the characteristics of pyomyositis in pediatric patients.

METHODS

Prospective analytical study of hospitalized children diagnosed with pyomyositis from May 2016 to April 2017 at the Ricardo Gutiérrez Children's Hospital, Buenos Aires, Argentina.

RESULTS

Twenty-one patients with pyomyositis were identified. Annual rate: 21.5/10,000 admissions (95% CI 4.65-71.43). The median age was 5.4 years (range 1.25-11.6). The lower limbs were the most affected site. C-reactive protein (CRP) was elevated in all patients, with a mean of 124 mg/L (SD 96), being significantly higher in patients with bacteremia: 206 (DS 101) vs 98 (DS 81), p = 0.02. Bacterial cultures were positive in 17/21 (80.9%): 15 methicillin-resistant Staphylococcus aureus (MRSA), and 2 Streptococcus pyogenes. Blood cultures were positive in 5 (23.8%).

CONCLUSION

MRSA-community acquired is the predominant pathogen in our setting. In the selection of the appropriate empirical treatment, the local resistance pattern and the CRP value should be taken into account.

Remarks on the possibility of introducing the fractionated dose of the inactivated poliomyelitis vaccine in the Latin American Child Immunization Schedule

Given that the last notified case of poliomyelitis due to wild poliovirus type 2 was in 1999, in 2012, the Strategic Advisory Group of Experts on Immunization (SAGE) of the World Health Organization (WHO) recommended the withdrawal of the type 2 component of oral polio vaccine (OPV) and the introduction of a bivalent OPV (bOPV) in all countries by 2016. WHO recommended also that the withdrawal should be preceded by the introduction of at least one dose of inactivated poliovirus vaccine (IPV) in routine immunization schedules. The introduction of IPV prior to the change of the bOPV in 2016 to trivalent OPV (tOPV) was based on the concept of ensuring that a substantial proportion of the population would be protected against type 2 polio after the removal of the type 2 OPV. However, the world's two producers of IPV (Bilthoven Biologicals and Sanofi) have faced problems in the production of this vaccine and therefore reported a reduction of the global supply of IPV. In response to the potential shortage of IPV, at a meeting held on March 10 2017, the SAGE and Technical Advisory Group (TAG) of the Pan American Health Organization (PAHO) urged the countries in the Latin American region to replace the routine administration of the full doses of inactivated polio vaccine (IPV-C) in the immunization schedule (administered by intramuscular route), administering a fraction of the full dose in two intradermal shots (IPV-f). The possibility of this strategy was analyzed by opinion leaders convened by the Paraguayan Society of Pediatrics with the support of the Latin American Society of Pediatric Infectious Diseases (SLIPE) and Latin American Association of Pediatrics (ALAPE). This document presents the results of the discussion.

Clinical and epidemiological impact of respiratory syncytial virus and identification of risk factors for severe disease in children hospitalized due to acute respiratory tract infection

INTRODUCTION

Severe acute respiratory tract infection (ARTI) is a very common cause of hospitalization in pediatrics; respiratory syncytial virus (RSV) is the major etiologic agent. Accurately defining the burden of RSV life-threatening disease (LTD) and its risk factors is a challenge.

OBJECTIVES

To know the impact of RSV in children hospitalized due to ARTI and describe the risk factors for LTD.

MATERIALS AND METHODS

Prospective study in children < 2 years old hospitalized due to ARTI during 2012-2013 at Hospital de Niños "R. Gutiérrez." LTD was defined as requiring non-invasive ventilation and/or mechanical ventilation.

RESULTS

622 studied children, 372 were RSV(+) (59.8 %). Annual rate of hospitalization due to RSV in infants < 1 year old: 956 (95 % CI: 858-1062)/10 000hospitalizations. RSV caused 56/78 (71.8 %) cases of LTD; 42 (75 %) were previously healthy subjects; 32 (76.2 %) were < 6 months old. In the multivariate analysis, RSV was a risk factor for LTD (adjusted odds ratio [aOR]: 2.04; 95 % CI: 1.15-3.63; p = 0.014). A differential effect by sex was identified in RSV(+) patients: over-crowding was a risk factor for LTD in males (aOR: 2.36; 95 % CI: 1.07-5.21; p = 0.033); breastfeeding was a significant protective factor in females (aOR: 0.342; 95 % CI: 0.13-0.91; p = 0.032).

CONCLUSIONS

RSV caused more than half of ARTI cases and mostly affected previously healthy patients < 1 year old. Males living in overcrowding conditions and females who were not breastfed were at the greatest risk for LTD.

[Remarks on the possibility of the introduction of fractionated dose of the inactivated poliomyelitis vaccine in the Latin American Child Immunization Schedule]

As last notified case of poliomyelitis due to wild poliovirus type 2 was 1999, in 2012, the Strategic Advisory Group of Experts on Immunization (SAGE) of the World Health Organization (WHO) recommended the withdrawal of the type 2 component of oral polio vaccine (OPV) and the introduction of bivalent OPV (bOPV) in all countries by 2016. WHO recommended also that the withdrawal should be preceded by the introduction of at least one dose of inactivated poliovirus vaccine (IPV) in routine immunization schedules. The introduction of IPV prior to the change of the bOPV in 2016 to trivalent OPV (tOPV) was based on the concept of ensuring that a substantial proportion of the population would be protected against type 2 polio after the removal of the type 2 OPV. However, the world's two producers of IPV (Bilthoven Biologicals and Sanofi) have faced problems in the production of this vaccine and therefore reported reduction in IPV global supply. In response to the possible shortage of IPV, the SAGE and Technical Adviser Group (TAG) of the Pan American Health Organization (PAHO), in the meeting of March 10, 2017, has urged that countries in the Latinamerican region should replace the routine administration of the full doses of polio inactivated vaccine (IPV-C) in the immunization schedule (administered by intramuscular route) by the administration of a fraction of the full dose in two shots by intradermal route (IPV-f). The possibility of this strategy was analyzed by leaders of opinions gathered by the call of the Paraguayan Pediatric Society with the support of the Latin American Society of Pediatric Infectious Diseases (SLIPE) and Latin American Association of Pediatrics (ALAPE). The results of the discussion are presented in this document.

Rapid Decrease in Rates of Hospitalization Resulting From Invasive Pneumococcal Disease and Community-Acquired Pneumonia in Children Aged <60 Months After 13-Valent Pneumococcal Conjugate Vaccine Introduction in Argentina

BACKGROUND

In January 2012, Argentina included universal pneumococcal vaccination in the routine childhood vaccination program using a 13-valent pneumococcal conjugate vaccine (PCV13). A 2 + 1 schedule (2 doses in the first year of life and a booster dose at 12 months of age) in children aged <2 years and 2-dose catch-up immunization in children aged 13 to 24 months was administered during the first year of vaccine introduction. The purpose of this study was to assess the burdens of invasive pneumococcal disease (IPD) and/or community-acquired pneumonia (CAP) in hospitalized children younger than 5 years during the first 2 years of the program compared to those in the prevaccination period in our setting.

METHODS

This was a multicenter, prospective, and descriptive study. Rates of hospitalization resulting from IPD and/or CAP in 5 pediatric reference centers across the country were analyzed (every 10 000 admissions). Clinical, epidemiologic, and microbiological data were recorded. Statistical analysis using Stata 8.0 was performed.

RESULTS

A comparison of rates of hospitalization resulting from global IPD and/or CAP in the prevaccine (2009-2011) and postvaccine (2012-2013) periods revealed significant decreases of 50% (P = .003) and 51% (P < .0001), respectively. Significant decreases were also observed in number of hospitalizations resulting from empyema (39%; P = .03) and pneumococcal empyema (67.8%; P = .007); the reduction was not statistically significant for pneumococcal CAP (58%; P = .18). Hospital stays for IPD and/or CAP decreased by 56%.

CONCLUSION

Rapid and significant decreases in the rates of hospitalization resulting from IPD and/or CAP during the first 2 years after PCV13 introduction were observed. A longer surveillance period is required to confirm these results and the effectiveness of the vaccination program.

Prevalence of Pertussis Antibodies in Maternal Blood, Cord Serum, and Infants From Mothers With and Those Without Tdap Booster Vaccination During Pregnancy in Argentina

BACKGROUND

Morbidity and mortality rates for pertussis in infants are high because disease often occurs before the onset of routine immunization or in those who do not complete a primary immunization series. Pertussis immunization is recommended during pregnancy to achieve antibody levels sufficient to protect young infants. To our knowledge, no previous reports of maternal pertussis immunization results in Latin America exist in the literature.

METHODS

This study compared pertussis antibody levels in newborns from mothers who received or did not receive a tetanus-diphtheria-acellular pertussis vaccination (TdapV) during pregnancy. Each mother's level of immunoglobulin G antibodies against pertussis toxin (IgG-PT) was measured with a validated, specific enzyme-linked immunosorbent assay (ELISA).

RESULTS

Paired mother and cord serum samples were compared in 105 mothers with and 99 mothers without a TdapV. At birth, the mothers with and those without a TdapV had serum IgG-PT geometric mean concentrations (GMCs) of 35.1 and 9.8 ELISA units (EU)/mL, respectively (P < .0001); cord blood GMCs were 51.3 and 11.6 EU/mL, respectively (P < .0003); and cord blood IgG-PT levels were <5 EU/mL in 2.9% and 16.1% of the cord blood samples, respectively (P < .001). The mothers received their TdapV at a mean (± standard deviation [SD]) of 24.7 ± 4.8 weeks' gestation. Vaccination timing did not affect the IgG-PT GMC at birth. Placental antibody transference efficiencies (measured as the ratio of the cord blood GMC to the maternal GMC) were 1.46 and 1.18 for mothers with and those without a TdapV, respectively. The IgG-PT GMCs were 17.7 EU/mL in 36 infants in their first month of life and 11.6 EU/mL in 32 infants in their second month of life.

CONCLUSIONS

Women who received a TdapV during pregnancy had significantly a higher serum/cord IgG-PT concentration at birth than mothers who did not receive a TdapV. Timing of the immunization was not correlated with antibody concentrations. Infants born to immunized mothers had significantly higher antibody levels during their first 2 months of life.

[Cervicofacial actinomycosis as differential diagnosis of cavum carcinoma: case report]

Paediatric actinomycosis is an infrequent infectious disease caused by Actinomyces spp. Cervicofacial infections are usually related to disruption in oral mucosal membranes. We discuss the case of a 15-year-old girl who refers an 8-month history of odynophagia and changes in her tone of voice after getting a tongue piercing. She received multiple antibiotic treatments with slight improvement. Nasopharyngeal carcinoma was diagnosed by endoscopic biopsy. The patient was referred to our Hospital for treatment but, when the biopsy was analyzed again, oncological pathology was excluded and oropharyngeal actinomycosis was diagnosed. She received a total of 6 months of antibiotic treatment with favorable evolution. While oral piercings have not been yet described as a risk factor for oropharyngeal actinomycosis, the mucosal disruption could favor the onset of this disease.

Pandemic influenza A/H1N1 2009 antibodies in the metropolitan area of Buenos Aires in Argentina

OBJECTIVE

To estimate the infection prevalence in Buenos Aires during the outbreak of pandemic influenza A/H1N1 2009 virus (A(H1N1)pdm09).

METHODS

A(H1N1)pdm09-specific antibodies were measured by hemagglutination inhibition assay in human serum samples collected 6 months after the outbreak and before the introduction of the A(H1N1)pdm09 vaccine in Argentina. Baseline levels of cross-reactive antibodies to A(H1N1)pdm09 were determined by testing 162 serum samples collected before 2009.

RESULTS

The overall seroprevalence of A(H1N1)pdm09 in 150 children and 427 adults was 28.9% (95% confidence interval (CI) 25-33%), with a 58.0% prevalence in children <19 years of age and an 18.7% prevalence in adults ≥19 years of age (p<0.001). The prevalence was 43.5% in children <5 years old and 60.6% among children aged 5-18 years. The prevalence in adults declined with increasing age: 24.9% in 19-39-year-olds, 9.7% in 40-59-year-olds, and 8.1% in those ≥60 years old. The prevalence of specific A(H1N1)pdm09 antibodies was higher compared with the baseline in children (p=0.014), adolescents (p<0.001), and adults <40 years old (p=0.017). Seroprevalence in health care workers was not different from the rest of the population (13.6% vs. 19.3%, respectively; p=0.421).

CONCLUSIONS

The prevalence of specific A(H1N1)pdm09 antibodies was high at 28.9%. The highest prevalence was observed in children, adolescents, and young adults.

[Metastatic infections in children with Staphylococcus aureus bacteremia]

Staphylococcus aureus is one of the most common infectious agents in children. It causes a broad spectrum of infections ranging from trivial to severe life-threatening presentations. The possibility of complications in case of Staphylococcus aureus bacteremia (SAB) appears to be high, being described in up to 43% of cases in adult patients. However, metastatic infections seems to be less frequent in pediatric patients. There is no agreement on when or to whom complementary tests should be requested to rule them out. The aim of this study is to describe the frequency and characteristics of secondary impacts of SAB identified at "Hospital Gutierrez" in a period of two years, and assess potential risk factors for their occurrence. Metastatic infection rate was 15.8%. The main risk factor was the persistence of positive blood cultures more than 48 hours.

[Primary meningococcal arthritis in pediatrics. Report of nine cases]

Primary meningococcal arthritis is an extremely uncommon type of invasive meningococcal disease, with an incidence of 1.5- 1.8% of all paediatric cases of pyogenic arthritis. It is defined as the presence of acute septic arthritis without association with meningitis or the classic meningococcaemia, and isolation of Neisseria meningitidis in synovial fluid and/or blood culture. Typically monoarticular, mostly affects large joints. Prognosis is excellent with appropriated treatment. The aim of this study is to report 9 cases of primary meningococcal arthritis, evaluated at Hospital de Niños "Dr. R. Gutiérrez" in a period of 3 years, and to discuss clinical and epidemiologic issues.

Safety and pharmacokinetics of urtoxazumab, a humanized monoclonal antibody, against Shiga-like toxin 2 in healthy adults and in pediatric patients infected with Shiga-like toxin-producing Escherichia coli

Shiga-like toxin-producing Escherichia coli (STEC) infection causes diarrhea, which is often bloody and which can result in potentially life-threatening hemolytic-uremic syndrome (HUS). Urtoxazumab, a humanized monoclonal antibody directed against the Shiga-like toxin 2 (Stx2) produced by STEC, has been developed as a promising agent for the prevention of HUS. Single randomized, intravenous, double-blind, placebo-controlled doses of urtoxazumab were administered to assess its safety and pharmacokinetics in healthy adults (0.1 to 3.0 mg/kg of body weight) and STEC-infected pediatric patients (1.0 and 3.0 mg/kg). No dose-related safety trends were noted, nor were antiurtoxazumab antibodies detected. The disposition of urtoxazumab showed a biexponential decline, regardless of the dose. In healthy adults, the mean terminal elimination half-life was consistent across the dose groups and ranged from 24.6 days (3.0-mg/kg dose group) to 28.9 days (0.3-mg/kg dose group). The mean maximum serum drug concentration (C(max)) ranged from 2.6 microg/ml at 0.1 mg/kg to 71.7 microg/ml at 3.0 mg/kg. The disposition of urtoxazumab following the administration of doses of 1.0 and 3.0 mg/kg in pediatric patients showed mean C(max)s of 19.6 and 56.1 microg/ml, respectively. Urtoxazumab was well tolerated, appears to be safe at doses of up to 3.0 mg/kg, and is a potential candidate for the prevention of HUS in pediatric patients.

[Congenital cytomegalovirus infection]

INTRODUCTION

Cytomegalovirus (CMV) is the most frequent cause of intrauterine infection and an important cause of auditory system damage and mental retardation in humans. Clinical presentation varies from asymptomatic form to lethal systemic dissemination.

OBJECTIVES

To describe clinical and laboratories manifestations, age at the moment of diagnostic, treatment and diagnostic test used in congenital cytomegalovirus infection.

POPULATION, MATERIAL AND METHODS

Observational, retrospective and descriptive study. Clinical histories of congenital CMV infected infants evaluated by Infectology Department of the Hospital General de Niños Dr. Ricardo Gutiérrez between January 2002 and December 2006 were analyzed.

RESULTS

Seventeen patients were evaluated. Mean age at diagnosis was 2.6 months. The most frequent symptom/sign were hepato-splenomegaly (76 %), jaundice (47 %), petechiae and hearing deficit (41 %). Anemia (53 %) and thrombocytopenia (40 %) were the most common laboratory abnormalities. Diagnosis was made exclusively by polymerase chain reaction (PCR)-CMV in one third of the patients, whereas one third was diagnosed by serology and the other third for both test. Five patients received ganciclovir as treatment. Only one had neutropenia.

CONCLUSIONS

Differential diagnosis of all newborns with hepatoesplenomegaly, jaundice and petechiae and anemia and/or thrombocytopenia must include congenital cytomegalo-virus infection. Early diagnosis allows a prompt intervention and a strict audiological follow up.

Hepatitis A vaccination of Argentinean infants: comparison of two vaccination schedules

BACKGROUND

Early immunization to protect infants against hepatitis A (HA) is recommended in intermediate or high endemic areas of the world, but little is known of the effects of maternal antibodies on the immune response. We studied the immunogenicity and reactogenicity of an inactivated HA vaccine administered in two different schedules to 2-month-old infants in an intermediate/high endemic area in Argentina.

METHODS

In this double-blind, randomized study 131 infants received either three doses (at 2, 4, 6 months of age [Group A]) or one dose (at 6 months of age [Group B]) of the pediatric inactivated HA vaccine, Avaxim 80, and a booster dose at 15-18 months. HAV antibodies were measured (ELISA) at 2, 7, 15-18 and 16-19 months of age. Immediate (30 min after injection) and solicited local and systemic reactions were recorded for 7 days after each injection.

RESULTS

Of 107/131 subjects (81.6%) who completed the study and who provided final serum samples after booster dose, 94 (87.8%) were seropositive at enrolment (>20 mIU/mL) with geometric mean concentrations (GMC) of 2989 and 3637 mIU/mL in Groups A and B, respectively. One month post-booster GMCs were 8236 mIU/ml (95% CI; 6304, 10760) and 1687 mIU/ml (1148, 2479) in Groups A and B, respectively, with 100% seroprotection.

CONCLUSIONS

The HA vaccine was well tolerated and induced immunological priming in both groups during the first year of life in spite of the presence of maternal antibodies. Post-booster GMCs achieved after one or three primary doses suggest a long-term protection against HA.

Clinical and epidemiologic aspects of human immunodeficiency virus-1-infected children in Buenos Aires, Argentina

BACKGROUND

Argentina has the sixth largest number of cumulative pediatric cases of acquired immunodeficiency syndrome (AIDS) in the Americas; therefore, this study was designed to characterize human immunodeficiency virus-1 (HIV-1) infection in children in Buenos Aires, Argentina.

MATERIALS AND METHODS

Medical records of 389 children at risk and infected with HIV-1, an urban population followed by the AIDS Reference Center at the Hospital de Niños "Dr. Ricardo Gutiérrez" of Buenos Aires, from February 1990 to June 1997, were retrospectively reviewed. Mother-infant pairs were analyzed according to clinical and epidemiologic patterns.

RESULTS

Perinatal transmission occurred in 94.9% of the 389 cases classified as seroreverter (n=104, 26.7%), exposed (n=64, 16.4%), asymptomatic (n=13, 3.4%), and symptomatic patients (n=208, 53.5%); 132 patients met the Centers for Disease Control and Prevention (CDC) criteria for AIDS. The main maternal risk factor was sexual transmission 58.9% (73.4% of their sexual partners were injection drug users [IDU]). Among the AIDS patients, the most common AIDS-defining condition and death-related disease were severe bacterial infection and Pneumocystis carinii pneumonia, respectively. Death occurred in 51 of 221 HIV-infected children. Low CD4 was related to death (P < 0.001). Mortality was estimated for two periods: January 1990 to December 1995 (G1) and January 1996 to May 1997 (G2). In G1, 37 of 127 (29.1%) died compared with 14 of 154 (9.1%) in G2 (P=0.001). The median age of death was 10 months for G1 and 29 months for G2 (P=0.01). The 3-year survival rate was 72% for G1 and 87% for G2 (log rank P=0.06).

CONCLUSIONS

Intravenous drug use is the leading risk factor among parents of children exposed to HIV. Infant mortality was related to age less than 12 months, low CD4 count, severe bacterial infection and P. carinii pneumonia. In this study, P. carinii pneumonia prophylaxis and combined antiretroviral therapy routinely implemented since 1996 has demonstrated a trend toward increased survival rates (P=0.06) and a lower mortality rate (P=0.001).

Safety and immunogenicity of a pediatric formulation of inactivated hepatitis A vaccine in Argentinean children

BACKGROUND

Children are a reservoir of hepatitis A virus and must be considered as primary targets of any immunization strategy. The safety and immunogenicity were evaluated for a new formulation of an inactivated hepatitis A vaccine, Avaxim 80 units, containing one-half the antigen dose of the adult formulation.

METHODS

The safety of two doses of this vaccine given 6 months apart was evaluated in an open study in 537 Argentinean children 12 months to 15 years old. Immunogenicity was evaluated at Weeks 0, 2, 24 and 27 in a subgroup of 120 subjects.

RESULTS

Two weeks after the first vaccine dose, >99% of initially seronegative children had seroconverted (titers > or =20 mIU/ml), with a geometric mean titer of 98.5 mIU/ml. Before booster at 24 weeks all subjects had seroconverted. A strong anamnestic response was observed after the second dose at which time the geometric mean titer had increased >35-fold, and antibody titers were consistent with long term protection. Immediate adverse reactions were observed in 3 of 537 (0.6%) subjects after the first dose. Local reactions were mild and transient and did not increase with subsequent doses. Among the systemic events reported during the 7-day follow-up period, 37 cases of fever after the first dose and 22 cases after the second dose were reported. Only 3 cases of fever were clearly related to vaccination (< or =38.2 degrees C) after the first injection, all of which subsided in less than 1 day.

CONCLUSIONS

This study demonstrated the safety and immunogenicity of a pediatric formulation of hepatitis A vaccine in children ages 12 months to 15 years in healthy children ages 12 to 47 months.

Shigella and Shiga toxin-producing Escherichia coli causing bloody diarrhea in Latin America

In Latin America, Shigella and shiga toxin-producing Escherichia coli are the two leading agents in the cause of bloody diarrhea. The already high and increasing antimicrobial resistance of Shigella also is a significant problem. Shiga toxin-producing E. coli is an emerging disease with life-threatening complications: hemolytic uremic syndrome. Although E. coli O157:H7 remains the most commonly recognized serotype, recently emerging, non-O157 bacteria may be the cause of a similar spectrum of disease in humans.

Perspectives on Shiga-like Toxin Infections in Argentina †

Argentina has the highest frequency of hemolytic uremic syndrome (HUS) in the world (300 cases/year). The risk of HUS in children from 6 to 48 months old is approximately 22/100,000 in Buenos Aires. In Argentina, HUS is the most frequent cause of acute renal damage and the second cause of chronic renal injury in children. We have shown that during the spring/summer season, the incidence of Shiga-like toxin (SLT)-associated bloody diarrhea in children less than 5 years old is 30 to 39%. The risk of HUS in SLT-associated bloody diarrhea is about 4 to 5%; 14% of children with SLT diarrhea developed incomplete HUS. Household contacts of children with HUS are commonly colonized with SLT-producing Escherichia coli (39%), and seroconversion occurs in 42% of these. No evidence of free fecal SLTs was observed in healthy children. In Argentina E. coli serotype O157:H7 has been associated with only 2 to 18% of HUS patients and in 4.5 to 7% of children with bloody diarrhea. Other serotypes were also recognized. About 20% of Argentine children start to eat meat at 5 months old, and 80% of them have meat in their diets at least three times a week. Eighty percent of the meat consumed is undercooked. Few data about the incidence of SLT-producing E. coli in cows in our country are available. E. coli O157:H7 was isolated in only 7.7% of calves aged 1 to 3 weeks with E. coli bacillosis from different farms in Argentina. Preliminary data show that SLT-producing E. coli were also present in stools from healthy animals and in fresh retail ground beef, determined by polymerase chain reaction.

Incomplete hemolytic-uremic syndrome in Argentinean children with bloody diarrhea

Argentina has an exceptionally high frequency of hemolytic-uremic syndrome (HUS). We sought to define prospectively the role of verocytotoxins (Shiga-like toxins [SLTs]) in 254 Argentinean children with grossly bloody diarrhea during spring and summer. Free fecal SLTs (I/II) and/or DNA probe-positive isolates were found in 99 (39%) of the children. During the follow-up period, HUS developed in 6 patients (4 with evidence of recent SLT infection based on stool studies); another 14 patients had some, but not all, of the abnormalities seen in typical HUS. The development of HUS or incomplete HUS in these children was significantly associated with recent SLT-Escherichia coli infection (p = 0.024). The high incidence of SLT-associated bloody diarrhea in Argentina explains, at least partially, the unusually high frequency of HUS. Our data indicate that incomplete forms of HUS may be common in patients with SLT-associated bloody diarrhea.

Tumor necrosis factor concentrations in hemolytic uremic syndrome patients and children with bloody diarrhea in Argentina

Hemolytic uremic syndrome (HUS) is thought to be a vascular endothelial injury disease. The mechanism of injury is unknown although verocytotoxins (Shiga-like toxins (SLTs)) are known to be associated with it. Recent evidence suggests that in vitro treatment of some endothelial cells with tumor necrosis factor alpha (TNF-alpha) dramatically increases their susceptibility to SLTs. We studied 25 children with HUS, 63 children with SLT-positive bloody diarrhea, 62 children with bloody diarrhea not associated with SLTs and 39 children admitted for elective surgery, included as an age- and season-matched control group. The TNF-alpha concentrations were found to be significantly elevated in children with HUS (range, 1 to 95 pg/ml; geometric mean, 32.2 pg/ml) compared with the healthy controls (range, 0 to 53 pg/ml; mean, 12.5 pg/ml; P < 0.001). Because it is hypothesized that TNF-alpha elevation might precede development of HUS, we also studied children with blood diarrhea. The TNF-alpha serum concentrations were significantly higher during the first 10 days after onset of bloody diarrhea than after the first 10 days (P < 0.02). Such elevation could be associated with vascular endothelial glycolipid receptor up-regulation and increased susceptibility to the effects of SLTs.

Computed tomography in purulent meningitis

Of 102 patients with bacterial meningitis admitted to the Children's Hospital of Buenos Aires, 25 were selected for computed tomographic (CT) scans on the basis of altered consciousness for more than 96 hours after admission, persistent or recurrent seizures after 72 hours of antibiotic therapy, development of focal neurologic signs, increased intracranial pressure or prolonged fever. Scan findings included hydrocephalus, cerebritis, vasculitis, subdural effusion, cerebral atrophy, abscess, and ependymitis. Serial CT scans demonstrated the progression or regression of some complications. The CT scan was very useful in indicating the need for neurosurgical procedures.

[Counterimmunoelectrophoresis in the diagnosis of Bordetella pertussis]

The serum of 50 patients between 25 days to 15 years old who were admitted with the diagnosis of pertussis syndrome were investigated for precipitating antibodies by means of discontinuous counterimmunolectrophoresis (CIED). The presence of antibodies for Bordetella pertussis antigen was shown in 28 cases. All samples were taken within the first 24/48 hours of admission and at convalescence. The technique is easy to carry out, quick and of low cost. This test offers an adequate and fast means to differentiate a Bordetella pertussis syndrome form others produced by different viral etiologies. Besides, this serologic technique shows earlier results and of lower cost than classic techniques such as agglutination and complement fixation which are more difficult to apply.