RESUMO
The aim of this study was to determine the frequency and allele associations of locus of enterocyte effacement encoded esp and tir genes among 181 enteropathogenic Escherichia coli (EPEC) strains (90 diarrhoea-associated and 91 controls) isolated from Peruvian children under 18 months of age. We analysed espA, espB, espD and tir alleles by PCR-RFLP. EPEC strains were isolated with higher frequency from healthy controls (91/424, 21.7%) than from diarrhoeal samples (90/936, 9.6%) (P<0.001); 28.9% of diarrhoeal and 17.6% of control samples were typical EPEC (tEPEC). The distribution of espA alleles (alpha, beta, beta2 and gamma) and espD alleles (alpha, beta, gamma and a new variant, espD-N1) between tEPEC and atypical EPEC (aEPEC) was significantly different (P<0.05). espD-alpha was more common among acute episodes (P<0.05). espB typing resulted in five alleles (alpha, beta, gamma and two new sub-alleles, espB-alpha2 and espB-alpha3), while tir-beta and tir-gamma2 were the most common intimin receptor subtypes. Seventy-two combinations of espA, espB, espD and tir alleles were found; the most prevalent combination was espA-beta, espB-beta, espD-beta, tir-beta (34/181 strains), which was more frequent among tEPEC strains (P<0.05). Our findings indicate that there is a high degree of heterogeneity among EPEC strains isolated from Peruvian children and that aEPEC and tEPEC variants cluster.
Assuntos
Escherichia coli Enteropatogênica/genética , Escherichia coli Enteropatogênica/isolamento & purificação , Infecções por Escherichia coli/epidemiologia , Infecções por Escherichia coli/microbiologia , Proteínas de Escherichia coli/genética , Variação Genética , Fosfoproteínas/genética , Criança , Pré-Escolar , Impressões Digitais de DNA , DNA Bacteriano/química , DNA Bacteriano/genética , Genótipo , Humanos , Lactente , Epidemiologia Molecular , Dados de Sequência Molecular , Peru , Reação em Cadeia da Polimerase , Polimorfismo de Fragmento de Restrição , Análise de Sequência de DNARESUMO
The aim of this study was to determine the prevalence, virulence factors (stx, eae, ehxA and astA) and phylogenetic relationships [PFGE and multilocus sequence typing (MLST)] of Shiga toxin-producing Escherichia coli (STEC) strains isolated from four previous cohort studies in 2212 Peruvian children aged <36 months. STEC prevalence was 0.4â% (14/3219) in diarrhoeal and 0.6â% (15/2695) in control samples. None of the infected children developed haemolytic uraemic syndrome (HUS) or other complications of STEC. stx1 was present in 83â% of strains, stx2 in 17â%, eae in 72â%, ehxA in 59â% and astA in 14â%. The most common serotype was O26â:âH11 (14â%) and the most common seropathotype was B (45â%). The strains belonged mainly to phylogenetic group B1 (52â%). The distinct combinations of alleles across the seven MLST loci were used to define 13 sequence types among 19 STEC strains. PFGE typing of 20 STEC strains resulted in 19 pulsed-field patterns. Comparison of the patterns revealed 11 clusters (I-XI), each usually including strains belonging to different serotypes; one exception was cluster VI, which gathered exclusively seven strains of seropathotype B, clonal group enterohaemorrhagic E. coli (EHEC) 2 and phylogenetic group B1. In summary, STEC prevalence was low in Peruvian children with diarrhoea in the community setting. The strains were phylogenetically diverse and associated with mild infections. However, additional studies are needed in children with bloody diarrhoea and HUS.
Assuntos
Infecções por Escherichia coli/microbiologia , Escherichia coli Shiga Toxigênica/classificação , Escherichia coli Shiga Toxigênica/genética , Adesinas Bacterianas/genética , Sequência de Bases , Estudos de Casos e Controles , Pré-Escolar , Estudos de Coortes , DNA Bacteriano/genética , Eletroforese em Gel de Campo Pulsado , Infecções por Escherichia coli/epidemiologia , Proteínas de Escherichia coli/genética , Feminino , Genes Bacterianos , Proteínas Hemolisinas/genética , Humanos , Lactente , Recém-Nascido , Masculino , Tipagem de Sequências Multilocus , Peru/epidemiologia , Filogenia , Prevalência , Sorotipagem , Toxina Shiga/genética , Escherichia coli Shiga Toxigênica/isolamento & purificação , Fatores de Virulência/genéticaRESUMO
Enteropathogenic Escherichia coli (EPEC) is a leading cause of infantile diarrhoea in developing countries. The aim of this study was to describe the allelic diversity of critical EPEC virulence genes and their association with clinical characteristics. One hundred and twenty EPEC strains isolated from a cohort diarrhoea study in Peruvian children were characterized for the allele type of eae (intimin), bfpA (bundlin pilin protein of bundle-forming pilus) and perA (plasmid encoded regulator) genes by PCR-RFLP. Atypical EPEC strains (eae+, bfp-) were the most common pathotype in diarrhoea (54/74, 73 %) and control samples from children without diarrhoea (40/46, 87 %). Overall, there were 13 eae alleles; the most common were beta (34/120, 28 %), theta (24/120, 20 %), kappa (14/120, 12 %) and mu (8/120, 7 %). There were five bfpA alleles; the most common were beta1/7 (10/26), alpha3 (7/26) and beta5 (3/26). There were three perA alleles: beta (8/16), alpha (7/16) and gamma (1/16). The strains belonged to 36 distinct serogroups; O55 was the most frequent. The gamma-intimin allele was more frequently found in diarrhoea episodes of longer duration (>7 days) than those of shorter duration (3/26, 12 % vs 0/48, 0 %, P<0.05). The kappa-intimin allele had the highest clinical severity score in comparison with other alleles (P<0.05). In Peruvian children, the virulence genes of EPEC strains are highly variable. Further studies are needed to evaluate additional virulence markers to determine whether relationships exist between specific variants and clinical features of disease.
Assuntos
Adesinas Bacterianas/genética , Escherichia coli Enteropatogênica/metabolismo , Infecções por Escherichia coli/microbiologia , Proteínas de Escherichia coli/genética , Proteínas de Fímbrias/genética , Proteínas Repressoras/genética , Adesinas Bacterianas/metabolismo , Criança , Estudos de Coortes , Diarreia/epidemiologia , Diarreia/microbiologia , Escherichia coli Enteropatogênica/genética , Infecções por Escherichia coli/epidemiologia , Proteínas de Escherichia coli/metabolismo , Proteínas de Fímbrias/metabolismo , Humanos , Peru/epidemiologia , Proteínas Repressoras/metabolismo , VirulênciaRESUMO
Hemolytic uremic syndrome, a serious complication of Shiga toxin-associated diarrhea, is rare before 6 months of age. Immunologic and nonimmunologic factors present in human milk may partially explain this observation. In prior studies, we have demonstrated that human milk contains Gb3, the receptor for the B subunit of Shiga toxin, and also contains secretory IgA (sIgA) against the toxin. We therefore sought to determine the relative importance of milk glycolipid and toxin-specific sIgA in toxin binding. We studied two populations that differed in their frequency of exposure to Shiga toxin. Human milk samples obtained from healthy donors from Boston and Buenos Aires were separated by centrifugation into aqueous (antibody enriched) and cream (glycosphingolipid enriched) fractions. An emulsion of equal volumes of aqueous phase or cream layer of each sample and purified Shiga toxin was incubated, and the amount of free toxin present in each was determined by enzyme immunoassay. The cream layers bound 85%+/-2 (mean +/- SE) (Argentina milk samples) and 86%+/-1 (Boston milk samples) of Shiga toxin. In contrast, the soluble fraction in samples from Buenos Aires, a population expected to frequently have antibodies to Shiga toxin, bound more toxin (48%+/-2) than did this fraction in samples from Boston, an area where toxin exposure is infrequent (30%+/-3) (P < 0.0001). Toxin-binding lipids present in human milk are biologically active and may contribute to the putative protective effect of human milk. In a population frequently exposed to Shiga toxins (Argentina), protection may be due to both immune (sIgA), and nonimmune (lipid) factors present in human milk. In a population infrequently exposed to Shiga toxins, cream fraction-associated glycolipids represent the major toxin binding activity in human milk.
Assuntos
Glicolipídeos/metabolismo , Leite Humano/química , Toxina Shiga/metabolismo , Argentina , Boston , Cromatografia Líquida de Alta Pressão , Feminino , Glicolipídeos/análise , Glicolipídeos/isolamento & purificação , HumanosRESUMO
An infant had clinical signs suggestive of Hirschsprung disease as the initial manifestation of leukocyte adhesion deficiency. Chromosome studies showed a deletion of the distal third of the long arm of one chromosome 21, and flow cytometric studies confirmed the defective expression of CD18.
Assuntos
Doença de Hirschsprung/diagnóstico , Síndrome da Aderência Leucocítica Deficitária/diagnóstico , Antígenos CD11/sangue , Antígenos CD18/sangue , Deleção Cromossômica , Cromossomos Humanos Par 21 , Diagnóstico Diferencial , Evolução Fatal , Doença de Hirschsprung/genética , Humanos , Lactente , Síndrome da Aderência Leucocítica Deficitária/genética , MasculinoRESUMO
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.
Assuntos
Diarreia Infantil/epidemiologia , Diarreia/epidemiologia , Síndrome Hemolítico-Urêmica/epidemiologia , Argentina/epidemiologia , Toxinas Bacterianas/análise , Contagem de Células Sanguíneas , Distribuição de Qui-Quadrado , Pré-Escolar , Citotoxinas/análise , DNA Bacteriano/genética , Diarreia/complicações , Diarreia/diagnóstico , Diarreia Infantil/complicações , Diarreia Infantil/diagnóstico , Escherichia coli/genética , Escherichia coli/isolamento & purificação , Fezes/química , Fezes/microbiologia , Feminino , Síndrome Hemolítico-Urêmica/diagnóstico , Síndrome Hemolítico-Urêmica/etiologia , Humanos , Incidência , Lactente , Masculino , Hibridização de Ácido Nucleico , Estudos Prospectivos , Toxinas ShigaRESUMO
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.
Assuntos
Síndrome Hemolítico-Urêmica/sangue , Síndrome Hemolítico-Urêmica/fisiopatologia , Fator de Necrose Tumoral alfa/análise , Argentina , Estudos de Casos e Controles , Pré-Escolar , Diarreia/etiologia , Fezes/microbiologia , Feminino , Síndrome Hemolítico-Urêmica/complicações , Humanos , Imunoensaio , Lactente , Masculino , PrognósticoRESUMO
The proportion of Shigella infections that occur asymptomatically in young children has not been established. A community-based cohort study of 367 infants was followed prospectively by weekly home visits from January, 1990, through December, 1991. Stool samples were collected weekly and when diarrhea occurred and were tested for Shigella and other enteropathogens. There were 2925 child months of observation and 65 episodes of Shigella infection. There were 3.1 episodes/100 child months during the warm season (May through September) and 0.97 episode/100 child months during the cold season. Shigella infections were rare during the first 6 months of life but increased with age (P < 0.0001). Overall 55% of detected infections were asymptomatic. The proportion of infections that were asymptomatic increased as age increased (P < 0.01). Symptom status was not significantly associated with Shigella species or season. All isolates from symptomatic and asymptomatic children had the 120- to 140-megadalton virulence plasmid. We conclude that infections with virulent strains of Shigella are commonly asymptomatic in Mexican children during the first 2 years of life.
PIP: During January 1990-December 1991, each week, field workers visited the home of 367 children aged 0-24 months from a periurban area southwest of Mexico City (San Pedro Martir and San Andres Totoltepec, Tlalpan) and collected stool specimens from them to determine whether Shigella infections are often asymptomatic. The crude incidence rate of diarrhea, regardless of etiology, was 29 episodes/100 child months during the warmer and rainy months (May-September), while it was 21 episodes/100 child months for the rest of the year (October-April) (relative risk [RR] =1.38). 53 of all children (l4%) had 65 Shigella infections. The overall monthly incidence of symptomatic and asymptomatic Shigella infection was higher during May-September than October-April (3.13 vs. 0.97 episodes/100 children; RR = 3.22). 55% of all Shigella infections (36) were asymptomatic. 32% developed secretory-type diarrhea and 13% had blood present in the stool. The incidence of Shigella infections grew as did the age (0.4-8.2 episodes/100 child months for 0-6 month olds to 18-24 month olds; p 0.0001). The proportion of asymptomatic Shigella infections also increased with age (33% for 0-6 month olds, 40% for 7-12 month olds, 46% for 13-18 month olds, and 78% for 18-24 month olds; p 0.01). Shigella sonnei, S. flexneri, and S. boydii were the only species detected. The 120-140 megadalton virulence plasmid was present in all isolates from asymptomatic and symptomatic children. Mixed infections were rather common in both asymptomatic (47%) and symptomatic (45%) children. Among infants aged less than 12 year months, breast feeding infants were less likely to be infected with Shigella than nonbreast feeding infants (RR = 2.41). On the other hand, among children aged 12-24 months, nonbreast feeding was associated with a lower risk of Shigella infection (RR = 0.69). These findings show that Shigella infections in Mexican children aged 0-24 months range from asymptomatic infections to secretory diarrhea to bloody diarrhea.
Assuntos
Disenteria Bacilar/epidemiologia , Distribuição por Idade , Aleitamento Materno , Estudos de Coortes , Intervalos de Confiança , Disenteria Bacilar/microbiologia , Disenteria Bacilar/fisiopatologia , Fezes/microbiologia , Humanos , Incidência , Lactente , Recém-Nascido , México/epidemiologia , Estudos Prospectivos , Estações do Ano , Shigella boydii/isolamento & purificação , Shigella flexneri/isolamento & purificação , Shigella sonnei/isolamento & purificaçãoRESUMO
From January, 1990, to December 31, 1990, 75 children with multiply resistant Salmonella gastroenteritis were studied at the Children's Hospital "Ricardo Gutierrez" of Buenos Aires. These children ranged from 1 month to 15 years of age. Infection was community-acquired in 20 (26.6%), nosocomially acquired in 50 (66.7%) and undetermined in 5. Thirty-nine (52%) had grossly bloody stools. Fever occurred at some point in the clinical course in 61 children (81.3%) with a duration of 1 to 33 days (mean, 6.7 days). The duration of diarrhea (1 to 69 days) was longer in those who developed complications (P < 0.001). Six (8%) developed enterocolitis (2 with bowel perforation), 1 had a pulmonary abscess and 8 (11.4%) had bacteremia; 4 children died (5.3%). Salmonella typhimurium was the most common serovar (85.3%). Ninety percent minimum inhibitory concentration studies demonstrated that all strains were resistant to ampicillin (> 128 micrograms/ml), cephalothin (> 128 micrograms/ml), cefuroxime (> 128 micrograms/ml), nalidixic acid (> 256 micrograms/ml), rifampin (> 256 micrograms/ml), gentamicin (> 256 micrograms/ml) and tobramycin (256 micrograms/ml); 77.3% of strains were resistant to ceftazidime (32 micrograms/ml), 97.6% to netilmicin (> 256 micrograms/ml), 92.8% to amikacin (256 micrograms/ml), 24.4% to isepamicin (32 micrograms/ml), 5.3% to chloramphenicol (4 micrograms/ml) and 2.7% to cefoxitin (2 micrograms/ml). The 90% minimum inhibitory concentration of cefotaxime and ceftazidime was reduced by the addition of clavulanate. Aggressive multiply resistant Salmonella strains are a major pediatric problem in Buenos Aires.
Assuntos
Resistência Microbiana a Medicamentos , Gastroenterite/microbiologia , Infecções por Salmonella/microbiologia , Salmonella/efeitos dos fármacos , Adolescente , Aminoglicosídeos , Antibacterianos , Argentina , Cefalosporinas , Criança , Pré-Escolar , Feminino , Gastroenterite/complicações , Humanos , Lactente , Masculino , Salmonella/isolamento & purificação , Infecções por Salmonella/complicaçõesRESUMO
In a prospective randomized double-blind trial, pivmecillinam was compared with cotrimoxazole (TMP-SMX), both given orally for a period of 5 days, for the treatment of 59 children with shigellosis. 29 patients were treated with pivmecillinam and 30 with cotrimoxazole. 14% of shigella organisms isolated were resistant to pivmecillinam and 21% to TMP-SMX. The diarrhea persisted for a mean (+/- SD) period of 74 +/- 24.8 h in the pivmecillinam-treated patients versus 73.8 +/- 34 h in the TMP-SMX-treated patients. Duration of fever, positive stool culture, visible blood, occult blood, and pus cells in the stools were similar for both treatment groups. Five patients (17%) in the pivmecillinam group and 4 patients (13%) in the cotrimoxazole group fulfilled the clinical criteria that defined treatment failure. One patient (3.4%) in the pivmecillinam group and 2 (6.6%) in the TMP-SMX group evidenced recurrence of the diarrheal symptoms at the follow-up visit. No major drug-related side effects were observed in either group. We concluded that pivmecillinam is equivalent to cotrimoxazole in the treatment of shigellosis in children.