Clinical characterization and antimicrobial resistance of Escherichia coli in pediatric patients with urinary tract infection at a third level hospital of Quito, Ecuador / Caracterización clínica y resistencia antimicrobiana de Escherichia coli en pacientes pediátricos con infección del tracto urinario en un hospital de tercer nivel en Quito, Ecuador

Abstract: Background: Urinary tract infections (UTI) are among the most common infections in pediatric patients. The main etiopathogenic agent is Escherichia coli. The purpose of this study was to determine the antimicrobial resistance pattern of E. coli in pediatric patients and to understand their main clinical and laboratory manifestations. Methods: Fifty-nine patients were included in the study and classified into two groups: hospitalization (H) and external consultation (EC). Every patient presented urine cultures with the isolation of E. coli that included an antibiogram. Clinical signs and symptoms, urinalysis, complete blood count (CBC) and serum inflammatory markers were analyzed. Results: The most common clinical manifestations were fever (H: 76.5%; EC: 88%), vomiting (H: 32.4%; EC: 32%), hyporexia (H: 20.6%; EC: 16%), abdominal pain (H: 20.6%: EC: 28%), and dysuria (H: 14.7%; EC: 32%). Ten patients (16.95%) presented UTI for extended spectrum beta-lactamase (ESBL) E. coli. Ampicillin, nalidixic acid, and trimethoprim-sulfamethoxazole showed a higher resistance rate, being ampicillin the most significant (H: 88.2%; EC: 92%). Leukocyturia, bacteriuria and urine nitrites were frequent alterations in urinalysis (H: 52.9%; EC: 92%). In ESBL E. coli patients, a positive correlation was found between leukocytes in CBC and C-reactive protein (r = 0.9, p < 0.01). Diarrhea and foul-smelling urine were associated with E. coli resistance. Conclusions: The presence of leukocytes, bacteria, nitrites and the Gram stain are the most common indicators. Nitrofurantoin and phosphomycin are good therapeutic options. However, an antibiogram must be conducted to determine the best therapeutic agent.

Resumen: Introducción: Las infecciones de tracto urinario (ITU) se encuentran entre las más frecuentes en pediatría, siendo Escherichia coli el principal agente etiopatogénico. El objetivo de este estudio fue determinar el patrón de resistencia antimicrobiana de E. coli en pacientes pediátricos y conocer sus principales manifestaciones clínicas y de laboratorio. Métodos: Se incluyeron en el estudio 59 pacientes en dos grupos: hospitalización (H) y consulta externa (CE). En cada uno se realizó un urocultivo y un antibiograma con aislamiento de E. coli. Se analizaron signos y síntomas, uroanálisis, hemograma y marcadores séricos de inflamación. Resultados: Las manifestaciones clínicas más frecuentes fueron fiebre (H: 76.5%; CE: 88%), vómito (H: 32.4%; CE: 32%), hiporexia (H: 20.6%; CE: 16%), dolor abdominal (H: 20.6%: CE: 28%) y disuria (H: 14.7%; CE: 32%). Diez pacientes (16.95%) presentaron ITU por E. coli beta-lactamasa de espectro extendido (BLEE). La ampicilina, ácido nalidíxico y trimetroprim con sulfametoxazol mostraron alta resistencia, siendo ampicilina la más significativa (H: 88.2%, CE: 92%). Leucocituria, bacteriuria y nitritos en orina fueron frecuentes en el uroanálisis. En pacientes con E. coli BLEE se encontró una correlación positiva entre los leucocitos y la proteína C reactiva (r = 0.9, p < 0.01). La diarrea y el mal olor en la orina se asociaron con resistencia de E. coli. Conclusiones: La leucocituria, la bacteriuria, los nitritos y la tinción Gram son los indicadores más frecuentes de ITU. La nitrofurantoina y fosfomicina son buenas opciones terapéuticas. Sin embargo, debe realizarse un antibiograma para determinar el mejor tratamiento.

Skin microcirculatory changes reflect early the circulatory deterioration in a fulminant sepsis model in the pig

PURPOSE: In the pathophysiology of sepsis tissue perfusion dysfunction is a crucial driving force. Thus the early recognition is highly important. Concerning the early hours of bacteremia, and the systemic inflammatory response reaction leading to sepsis we aimed to investigate the micro- and macrocirculatory changes. METHODS: In 20 juvenile Hungahib pigs were anesthetized and the femoral artery and external jugular vein were prepared unilaterally and cannulated. For assisted ventilation tracheostomy was performed. In Sepsis group (n=11) live E. coli was intravenously administered (increasing concentration, 9.5x10∧6 in 3h). In Control group (n=9) bacteria-free saline was administered at the same volume. Modified shock index (MSI), core and skin temperature, and skin microcirculation (laser Doppler) were measured before inducing bacteremia then hourly for 4h. RESULTS: In Control group parameters were stable, while six animals in the Sepsis group died before the 4th hour. Core and skin temperature did not show significant alterations. In Sepsis group microcirculation showed a large impairment already by the 1st hour, while in MSI only by the 3rd hour. CONCLUSION: During bacteremia and the early phase of sepsis microcirculatory impairment can be detected soon, even hours before the deterioration in hemodynamic parameters in this porcine model. .

The discovery of cholera - like enterotoxins produced by Escherichia coli causing secretory diarrhoea in humans.

Non-vibrio cholera has been recognized as a clinical entity for as long as cholera was known to be caused by Vibrio cholerae. Until 1968, the aetiologic agent of this syndrome was not known. Following a series of studies in patients with non-vibrio cholera it was found that these patients had large concentrations of Escherichia coli in the small bowel and stools which produced cholera toxin-like enterotoxins, and had fluid and electrolyte transport abnormalities in the small bowel similar to patients with documented cholera. Furthermore, these patients developed antibodies to the cholera-like enterotoxin. Later studies showed that these strains, when fed to volunteers produced a cholera-like disease and that two enterotoxins were found to be produced by these organisms: a heat-labile enterotoxin (LT) which is nearly identical to cholera toxin, and a heat-stable enterotoxin (ST), a small molecular weight polypeptide. E. coli that produced one or both of these enterotoxins were designated enterotoxigenic E. coli (ETEC). ETEC are now known not only to cause a severe cholera-like illness, but to be the most common bacterial cause of acute diarrhoea in children in the developing world, and to be the most common cause of travellers’ diarrhoea in persons who visit the developing world.

Diferença de patogenicidade entre Escherichia coli enteroinvasora e Shigella flexneri em modelo experimental de infecção intestinal / Diference in pathogenicity between enteroinvasive Escherichia coli and Shigella flexneri in an experimental model of intestinal infection

Neste trabalho, esclarecemos tópicos da patogenicidade de EIEC que sustentam a sua menor virulência quando comparada à S. flexneri, e mostramos a importância das células dendríticas (CD) nesse processo. Estudou-se o comportamento de EIEC e S. flexneri quando em contato com células Caco-2, avaliando-se uma cinética de expressão dos genes envolvidos na invasão e disseminação bacteriana. Em geral, todos os genes foram menos expressos em EIEC, fato corroborado pelo fenótipo de disseminação bacteriana, onde EIEC foi menos eficiente do que Shigella. Também foi avaliada a modulação da resposta inflamatória de células dendríticas intestinais murinas pela produção de citocinas, expressão de moléculas co-estimulatórias e apresentação de antígenos, após desafio das células com as bactérias. Os resultados sugerem que EIEC induz a uma resposta protetora ao hospedeiro, enquanto que Shigella estaria "driblando" o sistema imune, além de provavelmente super-estimular o sistema imune adaptativo, fato que poderia levar a um agravamento da doença. As ações integradas das células Caco-2, células dendríticas e estímulos bacterianos foram estudadas em cocultura celular. Observou-se que EIEC e suas proteínas secretadas induzem a migração das CDs ao compartimento apical da co-cultura; nada foi observado quando o desafio se deu com Shigella...

Beneficial effect of recombinant human growth hormone on the intestinal mucosa barrier of septic rats

The objective of the present study was to investigate the effects of recombinant human growth hormone (rhGH) on the intestinal mucosa barrier of septic rats and explore its possible mechanism. Female Sprague-Dawley rats were randomized into three groups: control, Escherichia coli-induced sepsis (S) and treatment (T) groups. Groups S and T were subdivided into subgroups 1d and 3d, respectively. Expression of liver insulin-like growth factor-1 (IGF-1) mRNA, Bcl-2 and Bax protein levels and the intestinal Bax/Bcl-2 ratio, and plasma GH and IGF-1 levels were determined. Histological examination of the intestine was performed and bacterial translocation was determined. rhGH significantly attenuated intestinal mucosal injuries and bacterial translocation in septic rats, markedly decreased Bax protein levels, inhibited the decrease of Bcl-2 protein expression and maintained the Bax/Bcl-2 ratio in the intestine. rhGH given after sepsis significantly improved levels of plasma GH (T1d: 1.28 ± 0.24; T3d: 2.14 ± 0.48 æg/L vs S1d: 0.74 ± 0.12; S3d: 0.60 ± 0.18 æg/L; P < 0.05) and IGF-1 (T1d: 168.94 ± 65.67; T3d: 201.56 ± 64.98 æg/L vs S1d: 116.72 ± 13.96; S3d: 107.50 ± 23.53 æg/L; P < 0.05) and expression of liver IGF-1 mRNA (T1d: 0.98 ± 0.20; T3d: 1.76 ± 0.17 vs S1d: 0.38 ± 0.09; S3d: 0.46 ± 0.10; P < 0.05). These findings indicate that treatment with rhGH had beneficial effects on the maintenance of the integrity of the intestinal mucosa barrier in septic rats.

Characterization of an animal model of severe sepsis associated with respiratory dysfunction

PURPOSE: Pathophysiological studies in humans regarding sepsis are difficult to perform due to ethical and methodological concerns. In this context, animal models of sepsis can be useful to better understand this condition and to test therapeutic strategies. The purpose of this study was to characterize a feasible and clinically relevant model of sepsis in pigs that could be useful for testing different therapeutic interventions. METHODS: 5 White Large pigs were anesthetized, arterial and pulmonary catheters were introduced, and sepsis was induced by fecal peritonitis. Several biochemical indicators of organ dysfunction and infectious parameters were measured. The pigs were monitored until death, when fragments of organs were removed for pathology. Three animals without peritonitis served as controls and were sacrificed 24 hours after surgery without developing significant changes in organ function. RESULTS: Septic pigs survived 17 hours on average (range, 16-18 h), and Escherichia coli was recovered from blood cultures. They developed a significant decrease in left ventricular work and a nonsignificant reduction in mixed venous oxygen saturation. Respiratory dysfunction was characterized by a decrease in the PaO2/FiO2 ratio and respiratory compliance. Pathology of the lungs revealed areas of pulmonary collapse, hemorrhage, pulmonary congestion, and discrete neutrophil infiltrate. CONCLUSIONS: Fecal peritonitis in pigs is a clinically relevant model of sepsis associated with acute lung injury without direct pulmonary insult. This model may prove to be useful for studying pathogenic aspects of secondary lung injury as well as for validating ventilatory or pharmacologic interventions.

PROPOSTA: Estudos sobre sepse envolvendo sua fisiopatologia são difíceis de serem realizados devido a razões éticas e metodológicas. Neste sentido, modelos animais criam oportunidades de estudos para entender a fisiopatologia e testar estratégias terapêuticas. O objetivo deste estudo foi criar um modelo relevante de choque séptico em porcos para testar e entender diferentes intervenções. MÉTODOS: 5 porcos da raça "White Large" foram anestesiados e monitorizados com uma linha arterial e um cateter de artéria pulmonar. Uma peritonite fecal foi induzida através de laparotomia. Marcadores de disfunções orgânicas e infecciosos foram mensurados. Todos porcos evoluíram até a morte e amostras de órgãos foram coletadas para exame anátomo patológico. Três animais controles com o mesmo preparo cirúrgico e sem peritonite foram sacrificados após 24 horas de evolução, sem desenvolver mudanças significativas nas funções orgânicas. RESULTADOS: Os animais séptico sobreviveram na média 17 horas (16 - 18h), e Escherichia coli foi cultivada nas amostras de sangue. Os animais sépticos evoluíram com redução do trabalho de ventrículo esquerdo. A disfunção respiratória foi caracterizada por uma redução na relação PaO2/FiO2 e na complacência respiratória. A anatomia patológica dos pulmões revelou colapso pulmonar, hemorragia, congestão e infiltrado neutrofílico. CONCLUSÕES: A peritonite fecal em porcos é um modelo de choque séptico clinicamente relevante e associada a uma lesão pulmonar sem um insulto direto. Este é um modelo que pode ser utilizado para estudar aspectos fisiopatológicos das lesões pulmonares secundárias, assim como para estudar intervenções ventilatórias ou farmacológicas.

Papel de la Toxina Shiga en el sindrome urémico hemolítico / Role of the Shiga toxin in the hemolytic uremic syndrome

In the last years, infection associated with Shiga toxin-producing Escherichia coli (STEC) and subsequent Hemolitic-Uremic Syndrome (HUS) became relevant as a public health since it was considered as one of the most important emergent patogen present in the food contaminated by cattle feces. STEC infection may be asymptomatic or begins with a watery diarrhea that may or may not progress to bloody diarrhea (hemorrhagic colitis) and HUS. In Argentina, HUS is the most common pediatric cause of acute renal insufficiency and the second cause of chronic renal failure. Up to now, STEC infection lacks of known effective treatment strategies that diminish risk of progression to HUS. The mechanisms by which Shiga toxin (Stx) induce HUS may help to find strategies to prevent or ameliorate HUS. In this article, recent progress that has contributed to understanding the disease pathogenesis of STEC is reviewed. New strategies to prevent further uptake of Shiga from the gut, either during the diarrheal phase or once HUS has developed are discussed.

Postdiarrheal Shiga toxin-mediated hemolytic uremic syndrome similar to septic shock

The inflammatory response of host endothelial cells is included in the development of vascular damage observed in enterohemorrhagic Escherichia coli (EHEC) infection, resulting in hemolytic uremic syndrome (HUS). The response to a non-conventional treatment for a group of D+ HUS (diarrhea positive HUS) patients, with clinical hemodynamic parameters of septic shock was evaluated in this prospective study (1999-2003). Twelve children 2.8 +/- 0.6 years old, with D+ HUS produced by E. coli infection with serological evidence of Shiga toxin, presenting severe unstable hemodynamic parameters and neurological dysfunction at onset, were studied. The protocol included fresh frozen plasma infusions, methylprednisolone pulses (10mg/k/day) for three consecutive days and plasma exchange for five days, starting after admission to the intensive care unit (ICU). The twelve patients with increased pediatric risk of mortality (PRISM) score: 18 +/- 2 after admission to intensive care unit (ICU), required dialysis for 17.4 +/- 4 days, mechanical ventilator assistance for 10 +/- 1 days and early inotropic drugs support for 10.5 +/- 1 days. Neurological dysfunction included generalized tonic-clonic seizures lasting for 5.4 +/- 1 days, n:8. Focal seizures were present in the remaining patients. Dilated cardiomyopathy was present in 6 children. Eight children suffered hemorrhagic colitis. Nine patients survived. Within one year of the injury, neurological sequelae, Glasgow outcome scale (GOS) 3 and 4, were present in two patients, chronic renal failure in one patient. We suggest that early introduction of this protocol could benefit D+ HUS patients with hemodynamic instability and neurological dysfunction at onset. Further studies are likely to elucidate the mechanisms involved in this early adverse clinical presentation of D+ HUS patients.

La respuesta inflamatoria de la célula endotelial se incluye en el desarrollo del daño vascular observado en la infección por Escherichia coli enterohemorrágica que deviene en Síndrome Urémico Hemolítico (SUH). Se evaluó en forma prospectiva, entre 1999 y 2003, la respuesta a un tratamiento no convencional, en doce pacientes, edad 2.8 ± 0.6 años, que desarrollaron SUH con presencia de diarrea sanguinolenta (SUH D+) y evidencia serológica de toxina Shiga, los cuales en fase inicial presentaron parámetros hemodinámicoscompatibles con shock séptico y compromiso neurológico grave. El protocolo incluyó transfusión de plasmafresco, pulsos de metilprednisolona (10mg/k/día) por tres días consecutivos y plasmaféresis por cinco días, iniciados en las primeras 48 horas. Los doce pacientes ingresaron en terapia intensiva, presentando unapuntuación de riesgo de mortalidad pediátrica (PRISM): 18 ± 2, con requerimiento de diálisis por 17.4 ± 4 días, asistencia ventilatoria mecánica por 10 ± 1días y soporte temprano con drogas inotrópicas por un período de10.5 ± 1 días. La disfunción neurológica se presentó con convulsiones tónico-clónicas generalizadas por 5.4 ±1 días en 8 pacientes y con convulsiones focalizadas en los restantes. Seis pacientes desarrollaron miocardiopatíadilatada y 8 presentaron colitis hemorrágica. Sobrevivieron a la etapa aguda de la enfermedad 9 pacientes. Alfinalizar el primer año de seguimiento, dos de ellos presentaban secuelas neurológicas (escala de seguimientode Glasgow; GOS 3 y 4 respectivamente) y uno, fallo renal crónico. La introducción temprana de este protocolo podría beneficiar a pacientes con SUH D+ con inestabilidad hemodinámica grave y disfunción neurológica al inicio. Los mecanismos involucrados en esta temprana presentación clínica adversa de SUH D+ permanecen aún sin dilucidar.

Effects of decreased cerebral perfusion pressure on cerebral hemodynamics, brain cell membrane function and energy metabolism during the early phase of experimental Escherichia coli meningitis in the newborn piglet

In this study, we tested the hypothesis that decreased cerebral perfusion pressure (CPP) induces cerebral ischemia and worsen brain damage in neonatal bacterial meningitis. Meningitis was induced by intracisternal injection of 10(9) colony forming units of Escherichia coli in 21 newborn piglets. Although CPP decreased significantly at 8 hr after bacterial inoculation, deduced hemoglobin (HbD), measured as an index of changes in cerebral blood flow by near infrared spectroscopy, did not decrease significantly. In correlation analyses, CPP showed significant positive correlation with brain ATP and inverse correlation with brain lactate levels. CPP also correlated positively with HbD and oxidized cytochrome aa3 (Cyt aa3) by near infrared spectroscopy. However, CPP did not show significant correlation with cerebral cortical cell membrane Na+,K+-ATPase activity, nor with levels of lipid peroxidation products. In summary, decreased CPP observed in this study failed to induce cerebral ischemia and further brain injury, indicating that cerebrovascular autoregulation is intact during the early phase of experimental neonatal bacterial meningitis.

Escherichia coli enteropatogênica clássica (EPEC) / Enteropathogenic Escherichia coli (EPEC)

Escherichia coli enteropatogênica clássica (EPEC) ocupa especial importância como agente etiológico de diarréia aguda em crianças com até dois anos de idade, nos países subdesenvolvidos. É uma bactéria gram negativa, cuja açäo enteropatogênica foi primeiramente mencionada por Bray, em 1946. Seu mecanismo de patogenicidade permaneceu desconhecido até a década de 1970. A partir de entäo, uma série de trabalhos foram desenvolvidos, no sentido de esclarecer seu mecanismo fisiopatológico. Age sobre o intestino delgado levando a atrofia vilositária parcial e, mais raramente, subtotal, que se recupera quando a infecçäo regride.

Diagnóstico de infección urinaria en niños

La infección urinaria recurrente es el problema urológico más común en los niños. Con frecuencia el diagnóstico correcto se retrasa debido a que los síntomas son inespecíficos. Síntomas como fiebre, falta deganancia de pesos, llanto al orinar y enuresis son indicaciones específicas para ordenar un urocultivo. Para confirmar el diagnóstico de infección urinaria se debe examinar y cultivar por lo menos una orina fresca y limpia, ojalá del chorro medio. En niños sintomáticos se acepta como positivo un urocultivo con 100.000 colonias por mL, especialmente si todas las colonias son del mismo organismo. Escherichia coli es el microorganismo que se encuentra generalmente tanto en infecciones urinarias complicadas como no complicadas. En niños asintomáticos se necesitan tres urocultivos consecutivos positivos para hacer el diagnóstico. Se presentan las indicaciones para una adecuada recolección de la muestra para análisis del sedimento urinario y urocultivo. También se describen las principales pruebas utilizadas para el diagnóstico imaginológico.

Infecciones por Escherichia coli enteropatógena / Infectious diseases by Enteropathogenic Escherichia coli

Escherichia coli es una bacteria reconocida como uno de los principales agentes causantes de diarrea en humanos. Las diferentes capas de esta bacteria en humanos se clasifican en 5 categorías diferentes: enterotoxigénica (ETEC), enteroinvasiva (EIEC), enterohemorrágica (EHEC), enteroagregativa (EAggEC) y enteropatógena (EPEC). Las cepas del grupo EPEC son responsables de diarrea en niños menores, principalmente de países en desarrollo. El propósito de esta revisión consiste en presentar los conocimientos más recistentes relacionados con la patogénesis del grupo EPEC, así como las contribuciones de investigadores mexicanos en el conocimiento del microorganismo.