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.

Identificación directa con MALDI-TOF desde el frasco de hemocultivo a partir de subcultivos con incubación corta. Estudio multicéntrico / Direct identification with MALDI-TOF from the blood culture bottle from subcultures with short incubation. Multicenter study / Identificação direta com MALDI-TOF do frasco de hemocultura de subculturas com incubação curta. Estudo multicêntrico

Resumen El objetivo de este trabajo fue evaluar el rendimiento de la identificación realizada con MALDI-TOF a partir de la incubación de 3-5 h de subcultivos de hemocultivos positivos monomicrobianos que se comparó con la obtenida con la incubación de 24 h de los mismos. En dos hospitales se utilizó el sistema Vitek-MS (bioMérieux, Francia) y en uno el sistema Micro- Flex LT (Bruker, Daltonics). A partir de la incubación corta, MALDI-TOF identificó correctamente a 5/5 de las levaduras, a 91,1% (153/168) de las bacterias gram positivas, a 96,7% (119/123) de los bacilos gram negativos y a 93,6% (277/296) del total de cepas. La identificación por medio de MALDI-TOF a partir de una corta incubación de los subcultivos de los hemocultivos en medio sólidos es un método práctico, sencillo y confiable.

Abstract The objective of this work was to evaluate the performance of the identification carried out with MALDI-TOF from the 3-5 h incubation of subcultures of monomicrobial positive blood cultures that was compared with that obtained with the 24 h incubation of the same subcultures. The Vitek-MS system (bioMérieux, France) was used in two hospitals and the Micro-Flex LT system (Bruker, Daltonics) in one. With a short incubation, MALDI-TOF correctly identified 5/5 of the yeasts, 91.1% (153/168) of the gram-positive bacteria, 96.7% (119/123) of the gram-negative bacilli and 93.6% (277/296) of the total strains. Identification by means of MALDI-TOF with a short incubation of subcultures of blood cultures in solid media is a practical, simple and reliable method.

Resumo O objetivo deste trabalho foi avaliar o desempenho da identificação realizada com MALDI-TOF a partir de 3 a 5 h de incubação de subculturas de hemoculturas positivas monomicrobianas que foi comparada com a obtida com a incubação de 24 h das mesmas. O sistema Vitek-MS (bioMérieux, França) foi utilizado em dois hospitais e o sistema Micro-Flex LT (Bruker, Daltonics) em um. A partir da incubação curta, o MALDI-TOF identificou corretamente 5/5 das leveduras, 91,1% (153/168) das bactérias gram positivas, 96,7% (119/123) dos bacilos gram-negativos e 93,6% (277/296) das cepas totais. A identificação por meio de MALDI-TOF a partir de uma incubação curta das subculturas das hemoculturas em meio sólido é um método prático, simples e confiável.

Feohifomicosis por Exserohilum rostratum en un paciente pediátrico con leucemia linfoblástica aguda postransplante de médula ósea / Phaeohyphomycosis by Exserohilum rostratum in a pediatric patient with acute lymphoblastic leukemia after bone marrow transplantation

Resumen El género Exserohilum corresponde a hongos dematiáceos, la mayoría fitopatógenos, saprobios, de los cuales solo tres especies serían patógenas para el hombre: Exserohilum rostratum, Exserohilum longirostratum y Exserohilum mcginnisii. Se han reportado infecciones localizadas y sistémicas causadas por estos agentes, tanto en pacientes inmunocompetentes como inmunosuprimidos. Se presenta un caso de infección cutánea por E. rostratum en un paciente pediátrico con inmunocompromiso.

Abstract The genus Exserohilum consists of dematiaceous or darkly pigmented fungi. Most of the species included in this genus are phytopathogens, saprobes and only three of these species would be pathogenic to humans: Exserohilum rostratum, Exserohilum longirostratum and Exserohilum mcginnisii. Localized and systemic infections have been reported both in immunocompetent and immunosuppressed patients. A clinical case of cutaneous infection by E. rostratum in an immunocompromised pediatric patient is presented in this study.

[Phaeohyphomycosis by Exserohilum rostratum in a pediatric patient with acute lymphoblastic leukemia after bone marrow transplantation]. / Feohifomicosis por Exserohilum rostratum en un paciente pediátrico con leucemia linfoblástica aguda postransplante de médula ósea.

The genus Exserohilum consists of dematiaceous or darkly pigmented fungi. Most of the species included in this genus are phytopathogens, saprobes and only three of these species would be pathogenic to humans: Exserohilumrostratum, Exserohilumlongirostratum and Exserohilummcginnisii. Localized and systemic infections have been reported both in immunocompetent and immunosuppressed patients. A clinical case of cutaneous infection by E. rostratum in an immunocompromised pediatric patient is presented in this study.'

[Pediatric pyomyositis: Experience in a Pediatric Reference Center in Argentina]. / Piomiositis en niños: experiencia en un hospital pediátrico de referencia en 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.

Piomiositis en niños: experiencia en un hospital pediátrico de referencia en Argentina / Pediatric pyomyositis: experience in a Pediatric Reference Center in Argentina

Resumen Introducción: La piomiositis es la infección del músculo esquelético, entidad poco frecuente en pediatría. Objetivo: Describir las características de 21 niños con piomiositis. Métodos: Estudio prospectivo-analítico de niños ingresados con diagnóstico de piomiositis entre mayo de 2016 y abril de 2017 en el Hospital de Niños Ricardo Gutiérrez, Buenos Aires, Argentina. Resultados: Tasa de hospitalización de 21,5/10.000 admisiones (IC 95% 4,65- 71,43). La mediana de edad fue de 5,4 años (rango 1,25-11,6). El 90,4% presentaba algún factor predisponente. La localización más frecuente fue en miembros inferiores. La proteína C reactiva (PCR) estuvo elevada en todos los pacientes, con una media de 124 mg/L (DS 96), siendo significativamente más elevada en los pacientes que tuvieron hemocultivos positivos 206 (DS 101) vs 98 (DS 81), (p = 0,02). Se obtuvo rescate microbiológico en 17 pacientes (80,9%): Staphylococcus aureus resistente a meticilina (SARM) (n: 15) y Streptococcus pyogenes (n: 2). Se presentó con bacteriemia 23,8% de los pacientes. El 81% requirió drenaje quirúrgico. Conclusión: Staphylococcus aureus RM adquirido en la comunidad (SARMAC) es el patógeno predominante. En la selección del tratamiento empírico adecuado debería tenerse en cuenta: el patrón de resistencia local y el valor de PCR.

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.

Whole Genome Sequence Analysis of Burkholderia contaminans FFH2055 Strain Reveals the Presence of Putative ß-Lactamases.

Burkholderia contaminans is a member of the Burkholderia cepacia complex (Bcc), a pathogen with increasing prevalence among cystic fibrosis (CF) patients and the cause of numerous outbreaks due to the use of contaminated commercial products. The antibiotic resistance determinants, particularly ß-lactamases, have been poorly studied in this species. In this work, we explored the whole genome sequence (WGS) of a B. contaminans isolate (FFH 2055) and detected four putative ß-lactamase-encoding genes. In general, these genes have more than 93% identity with ß-lactamase genes found in other Bcc species. Two ß-lactamases, a class A (Pen-like, suggested name PenO) and a class D (OXA-like), were further analyzed and characterized. Amino acid sequence comparison showed that Pen-like has 82% and 67% identity with B. multivorans PenA and B. pseudomallei PenI, respectively, while OXA-like displayed strong homology with class D enzymes within the Bcc, but only 22-44% identity with available structures from the OXA family. PCR reactions designed to study the presence of these two genes revealed a heterogeneous distribution among clinical and industrial B. contaminans isolates. Lastly, blaPenO gene was cloned and expressed into E. coli to investigate the antibiotic resistance profile and confers an extended-spectrum ß-lactamase (ESBL) phenotype. These results provide insight into the presence of ß-lactamases in B. contaminans, suggesting they play a role in antibiotic resistance of these bacteria.

Multiple clones of metallo-ß-lactamase-producing Acinetobacter ursingii in a children hospital from Argentina.

Acinetobacter spp. are opportunistic pathogens being A. baumannii the most frequently identified in nosocomial settings. A. ursingii was mainly described as causing bacteremia and outbreaks in neonatal intensive care units. Ten A. ursingii isolates were recovered from rectal swab screening for carbapenemase-producing bacteria between June 2013 and December 2015 from a children hospital in Argentina. All ten isolates were metallo-ß-lactamase-producing, nine were positive for blaIMP-1 and one for blaNDM-1. IMP-positive isolates were also positive for blaOXA-58 gene. All isolates were susceptible to ciprofloxacin, colistin and minocycline, and nine were susceptible to ampicillin-sulbactam and gentamicin. Two A. ursingii displayed high level of resistance to aztreonam associated with blaCTX-M-15 in one isolate, and blaVEB-1 in the other. Eight SmaI-PFGE patterns were recognized. We evaluated the usefulness of Acinetobacter MLST-Pasteur scheme, to analyse A. ursingii isolates, however the rpoB gene was not amplified. A new set of primers were designed for specific amplification and sequencing, allowing the analysis of rpoB gene for this species. New alleles and the sequence types 748, 749, 750, 751, 993, 1186, 1187, and 1189 were included at the Acinetobacter MLST-Pasteur database. Those isolates showing related PFGE patterns were assigned to the same ST. To the best of our knowledge, this is the first report of MBL-producing A. ursingii in Argentina. The inclusion of A. ursingii species to the Acinetobacter MLST-Pasteur scheme allows deeper molecular characterization and a better understanding about the epidemiology of this germen.

Characterization of a multidrug resistant Citrobacter amalonaticus clinical isolate harboring blaNDM-1 and mcr-1.5 genes.

A multidrug resistant isolate, identified as Citrobacter amalonaticus using MALDI-TOF MS and confirmed by genomic analysis, was recovered from a pediatric patient in a hospital from Buenos Aires, Argentina. By whole-genome sequencing a total of 16 resistance genes were detected, including blaNDM-1 and mcr-1.5. To the best of our knowledge this is the first description of these two genes together in a clinical isolate of the Citrobacter genus.

Molecular Epidemiology of Methicillin-Resistant Staphylococcus aureus in Cystic Fibrosis Patients from Argentina.

Methicillin-resistant Staphylococcus aureus (MRSA) colonization in cystic fibrosis (CF) patients is an increasing problem in many countries. In our Respiratory Center at the Hospital de Niños "Dr. Ricardo Gutiérrez", Buenos Aires, Argentina, the prevalence has climbed from 23% in 1995 up to 32% in 2011. Our objective was to analyze the diversity of MRSA isolates recovered from respiratory samples of CF patients attending our center, characterizing their phenotypes and clonal distribution. Therefore, a prospective study was conducted on all CF patients attending the pediatric Respiratory Center between June 2012 and May 2013 to collect MRSA isolates. Antibiotic susceptibility testing, multilocus sequence typing, pulsed-field gel electrophoresis, spa typing, and agr genotyping were performed on collected isolates. The prevalence of MRSA during this period was 34.2%, and 71.9% of the patients were infected with isolates that carried SCCmec IV. High resistance rates were detected for gentamicin, erythromycin, clindamycin, ciprofloxacin, and rifampicin. Strains related to the community-associated MRSA clones, ST5-IV and ST30-IV, were the most frequently recovered. Remarkably, even though most of the isolates were related to these clones, the rate of multi-resistance shown in CF patients was higher than that reported for the same lineages recovered from other infections in our country.

Infección pulmonar por Arthrographis kalrae en un paciente con enfermedad granulomatosa crónica / Pulmonary infection by Arthrographis kalrae in patient with chronic granulomatous disease

Antecedentes: Arthrographis kalrae es un hongo hialino de crecimiento lento que, en su desarrollo, forma artroconidios. Es un patógeno oportunista que causa infecciones en personas inmunocomprometidas e inmunocompetentes, y ha sido aislado muy raramente en muestras clínicas de seres humanos. Caso clínico: Se describe el caso de un paciente con inmunodeficiencia primaria y afectación pulmonar con evolución tórpida. Presentó compromiso de ambos pulmones a pesar del tratamiento antibiótico y antifúngico instaurado. Durante su seguimiento, se realizaron múltiples biopsias pulmonares y se aisló A. kalrae en el cultivo de tejido pulmonar. Recibió tratamiento con posaconazol, con buena respuesta y remisión de las lesiones. Conclusión: Este es el primer caso reportado de infección pulmonar por A. kalrae en un paciente pediátrico con enfermedad granulomatosa crónica en Argentina.

Background: Arthrographis kalrae is a hyaline fungus that grows forming arthroconidia. It is an opportunistic pathogen that causes infections in immunocompromised as in immunocompetent people and has been rarely isolated from human clinical samples. Case report: We describe the case of a male child with primary immunodeficiency who initially presented unilateral pneumonia and progressed to bilateral involvement despite antibiotic, antifungal treatment. A. kalrae was diagnosed by pulmonary biopsy. He received posaconazole with resolution of disease. Conclusions: This is the first case of A. kalrae pulmonary infection in a pediatric patient with chronic granulomatous disease in Argentina.

Molecular characterization of a clinical Haemophilus parainfluenzae isolate with cefotaxime resistance and decreased susceptibility to fluoroquinolones.

We report an H. parainfluenzae clinical isolate resistant to cefotaxime and with decreased susceptibility to ciprofloxacin recovered from a patient with cystic fibrosis. The isolate had elevated MICs of ampicillin (256mg/L), amoxicillin-clavulanate (8mg/L), cefuroxime (8mg/L) and cefotaxime (4mg/L), and showed a ß-lactamase-producing amoxicillin-clavulanic acid-resistant (BLPACR) phenotype. A blaTEM-1 plus five amino acid substitutions in the PBP3 were found: Ser385Thr, Val511Ala, Ile519Val, Asn526Lys and Asp551Leu. MIC of ciprofloxacin was 0.5mg/L, and substitutions in gyrA (Ser84Tyr) and parC (Ser84Phe) genes were detected.

First case of human infection due to Pseudomonas fulva, an environmental bacterium isolated from cerebrospinal fluid.

We report the first case of human infection due to Pseudomonas fulva. P. fulva caused acute meningitis following the placement of a drainage system in a 2-year-old female. Additionally, the isolate displayed a VIM-2 carbapenemase in a class 1 integron context.

Erythromycin-resistant Streptococcus pyogenes in Argentina.

Erythromycin (ERY) resistance in Streptococcus pyogenes has recently emerged as a problem of growing concern all through the world. We are presenting the comparison of results of the continuous surveillance of erythromycin resistance in S. pyogenes performed since 1989 in the Hospital de Pediatría J.P. Garrahan of Buenos Aires City, with independently observed rates in other five centers of Buenos Aires and seven centers of six other Argentinian cities, obtained between 1999 and 2001. A significant increase of erythromycin resistance was observed among S. pyogenes isolated in the Hospital Garrahan (6.6% in 1998-1999 to 9.9% in 2000). Similar trends were also detected in other centers of other Argentinian cities when recent data were compared to results of a multicenter study performed in 1995. However, lower rates of resistance were recorded in Mendoza, Cipolletti and Neuquén in comparison with data of 1995, 1998 and 1998 respectively. The reason of such decreasing resistance rates deserves to be investigated. The average of ERY-resistance rates obtained in the surveyed centers was 6.7% (range 0.5-14.1%). Control of antimicrobial use should be performed to warrant the future effectiveness of macrolide antibiotics regarding the positive association between use and resistance. These results also suggest that susceptibility tests for macrolides should be performed whenever S. pyogenes is isolated in Argentina.

Erythromycin-resistant Streptococcus pyogenes in Argentina.

Erythromycin (ERY) resistance in Streptococcus pyogenes has recently emerged as a problem of growing concern all through the world. We are presenting the comparison of results of the continuous surveillance of erythromycin resistance in S. pyogenes performed since 1989 in the Hospital de Pediatría J.P.Garrahan of Buenos Aires City, with independently observed rates in other five centers of Buenos Aires and seven centers of six other Argentinian cities, obtained between 1999 and 2001. A significant increase of erythromycin resistance was observed among S. pyogenes isolated in the Hospital Garrahan (6.6

in 1998-1999 to 9.9

in 2000). Similar trends were also detected in other centers of other Argentinian cities when recent data were compared to results of a multicenter study performed in 1995. However, lower rates of resistance were recorded in Mendoza, Cipolletti and Neuquén in comparison with data of 1995, 1998 and 1998 respectively. The reason of such decreasing resistance rates deserves to be investigated. The average of ERY-resistance rates obtained in the surveyed centers was 6.7

(range 0.5-14.1

). Control of antimicrobial use should be performed to warrant the future effectiveness of macrolide antibiotics regarding the positive association between use and resistance. These results also suggest that susceptibility tests for macrolides should be performed whenever S. pyogenes is isolated in Argentina.

Perfil epidemiológico de las infecciones invasivas por streptococcus pneumoniae / Epidemiological profile of invasive infections caused by streptococcus pneumoniae

Introducción: streptococcus pneumoniae (Sp) causa enfermedades invasivas de alta morbilidad, registrándose en la última década un aumento de la resistencia antibiótica. Material y metodos. Con el objetivo de estudiar la epidemiología del Sp, su susceptibilidad antibiótica y los factores de riesgo de resistencia a penicilina (RP), se evaluaron en forma prospectiva 274 pacientes con infecciones invasivas por Sp internados en el HNRG entre 1993 y 1999, inclusive. La mediana de edad fue de 21,5 meses (rango 1-180), la relación varón/mujer fue de 1,7:1; 11,8 porciento eran desnutridos de II-III grado; 52,6 porciento tenía enfermedad de base (respiratoria crónica o recidivante, 38,9 porciento). A partir del aislamiento bacteriológico de Sp se realizó el seguimiento clínico-epidemiológico del paciente. Resultados: de 293 presentaciones clínicas, la más frecuente fue neumonía (64,2 porciento), siguiendo meningitis (11,6 porciento), sepsis/bacteriemia (10,9 porciento), peritonitis (7,8 porciento) y 16 pacientes presentaron formas asociadas. El Sp se recuperó de 325 materiales de cultivo: en sangre 55,1 porciento; líquido pleural 27,1 porciento; LCR 9,2 porciento; líquido peritoneal 5,5 porciento y otros 3,1 porciento. La RP global fue: 31,8 porciento (87/274), con 17,9 porciento resistencia (R) alta, observándose diferencias en la distribución anual. El 65,5 porciento (57/87) de las cepas RP también lo eran a cefalosporinas de tercera generación (C3ªG). Los factores de riesgo de infección por SpRP fueron: infección intrahospitalaria (RR 2,72; 2,00-3,69), tratamiento previo con ß-lactámicos (RR 2,61; 1,91-3,55), neumonía (RR 2,06; 1,32-3,22), edad < 2 años (RR 1,72; 1,18-2,49). los predictores independientes hallados con el análisis multivariado fueron: tratamiento antibiótico previo con ß-lactámicos (p=0,0003), infección intrahospitalaria (p=0,0019) y neumonía (p=0,0445). La letalidad fue de 6,2 porciento (17/274), no presentando correlación con la RP. Conclusión: Este tipo de estudios permite orientar conductas terapéuticas y el uso prudente de antibióticos

Perfil epidemiológico de las infecciones invasivas por Streptococcus pneumoniae: epidemiological profile / Invasive streptococcus pneumoniae

Introducción. Streptococcus pneumoniae (Sp) causa enfermedades invasivas de alta morbimortalidad, registrándose en la última década un aumento de la resistencia antibiótica. Material y métodos. Con el objetivo de estudiar la epidemiología del Sp, su susceptibilidad antibiótica y los factores de riesgo de resistencia a penicilina (RP), se evaluaron en forma prospectiva 274 pacientes con infecciones invasivas por Sp internados en el HNRG entre 1993 y 1999, inclusive. La mediana de edad fue de 21,5 meses (rango 1-180), la relación varón/mujer fue de 1,7:1; 11,8% eran desnutridos de II-III grado; 52,6% tenía enfermedad de base (respiratoria crónica o recidivante, 38,9%). A partir del aislamiento bacteriológico de Sp se realizó el seguimiento clínico-epidemiológico del paciente. Resultados. De 293 presentaciones clínicas, la más frecuente fue neumonía (64,2%), siguiendo meningitis (11,6%), sepsis/bacteriemia (10,9%), peritonitis (7,8%) y 16 pacientes presentaron formas asociadas. El Sp se recuperó de 325 materiales de cultivo: sangre, 55,1 %; líquido pleural, 27,1%; LCR, 9,2%; líquido peritoneal, 5,5% y otros, 3,1%. La RP global fue: 31,8% (87/274), con 17,9% resistencia (R) alta, observándose diferencias en la distribución anual. El 65,5% (57/87) de las cepas RP también lo eran a cefalosporinas de tercera generación (C3aG). Los factores de riesgo de infección por SpRP fueron: infección intrahospitalaria (RR 2,72; 2,00-3,69), tratamiento previo con ß lactámicos (RR 2,61; 1,91-3,55), neumonía (RR 2,06; 1,32-3,22), edad < 2 años (RR 1,72; 1,18-2,49). Los predictores independientes hallados con el análisis multivariado fueron: tratamiento antibiótico previo con ß-Iactámicos (p= 0,0003), infección intra hospitalaria (p= 0,0019) Yneumonía (p= 0,0445). La letalidad fue de 6,2% (17/274), no presentando correlación con laRP. Conclusión. Este tipo de estudios permite orientar conductas terapéuticas y el uso prudente de antibióticos.

Introduction. Streptococcus pneumoniae (Sp) is a main cause of morbidity and mortality in children, and the increasing rates of drug resistant strains have been reported. The objectives of this study were to determine the epidemiology of invasive pneumococcal infections and the risk factors of Sp penicillin resistance (PR). Material & methods. Two hundred seventy four children with invasive pneumococcal infections hospitalized in a children hospital, in the 1993-1999 period; the median age was 21.5 montlis (1 month-18 years), the male to female ratio was 1.7:1. Fifty two percent of cases reported an underlying disease. Results. The most frequent diseases were: pneumonia 64.2%, meningitis 11.6%, sepsislbacteriemia 10.9%, peritonitis 7.8%. Sp was recovered in 325 samples: blood in 55.1 %, pleural fluid 27.1 %, cerebrospinal fluid (CSF) 9.2%, peritoneal fluid 5.5% and other fluids obtained by puncture 3.1%. PR rate was 31.8% (87/274), 17.9% were highly resistant. Différences in the annual distribution was observed. 65.5% from PR strains were resistant to third generation cephalosporms too. PR was associated with: previous beta-lactam antibiotics therapy (RR 2.61; 1.91-3.55); nosocomial infection (RR 2.72; 2.00-3.69), pneumonia (RR 2.06; 1.32-3.22), and age under two years (RR 1.72; 1.182.49). Results from multivariate logistic regression analysis of binary predictors ofPR were: previous beta-Iactam antibiotics therapy (p=0,0003), nosocomial infection (p=0.0019) and pneumonia (p=0.0445). Mortality was 6.2% (17/274) without correlation with PR. Conclusion. These findings suggest the need for a continuous surveillance, control of drug resistant pneumococci and vaccination with an effective vaccine among high-risk patients.