RESUMO
This study aims to characterize the presence of virulence factors of enterotoxigenic Escherichia coli (ETEC) causing traveler's diarrhea. Among 52 ETEC isolates, the most common toxin type was STh, and the most frequent colonization factors (CFs) were CS21, CS6, and CS3. On the other hand, the nonclassical virulence factors EAST1 and EatA were frequently present.
Assuntos
Diarreia/microbiologia , Escherichia coli Enterotoxigênica/genética , Infecções por Escherichia coli/microbiologia , Genótipo , Escherichia coli Enterotoxigênica/patogenicidade , Humanos , Fatores de Virulência/genéticaRESUMO
Enterotoxigenic Escherichia coli (ETEC) ranks among the most relevant diarrheagenic pathogens. Efforts to design vaccines to fight ETEC have been focused on colonizing factors (CFs) and atypical virulence factors (AVF). An effective vaccine must account for differences in the regional prevalence of these CFs and AVFs to be truly effective in a given area. In the present study, the presence of 16 CFs and 9 AVFs, as well as the heat-stable (ST) variants (STh or STp), was established by polymerase chain reaction in 205 Peruvian ETEC isolates (120 from diarrhea cases and 85 from healthy controls). Ninety-nine (48.3%) isolates were heat-labile, 63 (30.7%) ST, and 43 (21.0%) presented both toxins. Of ST isolates, 59 (28.8%) possessed STh, 30 (14.6%) STp, five (2.4%) both STh and STp, and 12 (5.8%) were not amplified for any variant tested. The presence of CFs was associated with diarrhea (P < 0.0001). The presence of eatA as well as concomitant presence of CSI, CS3, and CS21 and of C5 and C6 was statistically related to diarrhea cases. The present results suggests that, if effective, a vaccine considering CS6, CS20, and CS21, together with EtpA, would provide protection against 64.4% of the isolates analyzed, whereas the addition of CS12 and EAST1 would lead to 83.9% coverage. Large studies are needed to establish both the ideal candidates to be considered to develop a vaccine effective in the area, and continuous surveillance is needed to detect displacement of circulating isolates that may compromise future vaccines.
Assuntos
Escherichia coli Enterotoxigênica , Infecções por Escherichia coli , Proteínas de Escherichia coli , Humanos , Infecções por Escherichia coli/epidemiologia , Escherichia coli Enterotoxigênica/genética , Peru/epidemiologia , Fatores de Virulência/genética , Diarreia/epidemiologia , Proteínas de Escherichia coli/genética , Enterotoxinas , Glicoproteínas de MembranaRESUMO
BACKGROUND: Antibiotic resistance is increasing worldwide, being of special concern in low- and middle-income countries. The aim of this study was to determine the antimicrobial susceptibility and mechanisms of resistance in 205 enterotoxigenic Escherichia coli (ETEC) isolates from two cohort studies in children <24 months in Lima, Peru. METHODS: ETEC were identified by an in-house multiplex real-time PCR. Susceptibility to 13 antimicrobial agents was tested by disk diffusion; mechanisms of resistance were evaluated by PCR. RESULTS: ETEC isolates were resistant to ampicillin (64%), cotrimoxazole (52%), tetracycline (37%); 39% of the isolates were multidrug-resistant. Heat-stable toxin producing (ETEC-st) (48%) and heat-labile toxin producing ETEC (ETEC-lt) (40%) had higher rates of multidrug resistance than isolates producing both toxins (ETEC-lt-st) (21%), p<0.05. Only 10% of isolates were resistant to nalidixic acid and none to ciprofloxacin or cefotaxime. Ampicillin and sulfamethoxazole resistance were most often associated with blaTEM (69%) and sul2 genes (68%), respectively. Tetracycline resistance was associated with tet(A) (49%) and tet(B) (39%) genes. Azithromycin inhibitory diameters were ≤15 mm in 36% of isolates, with 5% of those presenting the mph(A) gene. CONCLUSIONS: ETEC from Peruvian children are often resistant to older, inexpensive antibiotics, while remaining susceptible to ciprofloxacin, cephalosporins and furazolidone. Fluoroquinolones and azithromycin remain the drugs of choice for ETEC infections in Peru. However, further development of resistance should be closely monitored.
Assuntos
Antibacterianos/uso terapêutico , Azitromicina/uso terapêutico , Diarreia/microbiologia , Escherichia coli Enterotoxigênica/efeitos dos fármacos , Infecções por Escherichia coli/microbiologia , Fluoroquinolonas/uso terapêutico , Pré-Escolar , Estudos de Coortes , Diarreia/tratamento farmacológico , Diarreia/epidemiologia , Método Duplo-Cego , Escherichia coli Enterotoxigênica/isolamento & purificação , Infecções por Escherichia coli/complicações , Infecções por Escherichia coli/tratamento farmacológico , Feminino , Humanos , Lactente , Masculino , Testes de Sensibilidade Microbiana , Peru/epidemiologia , Reação em Cadeia da Polimerase em Tempo RealRESUMO
Secretory diarrhea caused by cholera toxin (CT) is initiated by binding of CT's B subunit (CTB) to GM1-ganglioside on the surface of intestinal cells. Lactoferrin, a breast milk glycoprotein, has shown protective effect against several enteropathogens. The aims of this study were to determine the effect of bovine-lactoferrin (bLF) on CT-induced intestinal fluid accumulation in mice, and the interaction between bLF and CT/CTB with the GM1-ganglioside receptor. Fluid accumulation induced by CT was evaluated in the mouse ileal loop model using 56 BALB/c mice, with and without bLF added before, after or at the same time of CT administration. The effect of bLF in the interaction of CT and CTB with GM1-ganglioside was evaluated by a GM1-enzyme-linked immunosorbent assay. bLF decreased CT-induced fluid accumulation in the ileal loop of mice. The greatest effect was when bLF was added before CT (median, 0.066 vs. 0.166 g/cm, with and without bLF respectively, p<0.01). We conclude that bLF decreases binding of CT and CTB to GM1-ganglioside, suggesting that bLF suppresses CT-induced fluid accumulation by blocking the binding of CTB to GM1-ganglioside. bLF may be effective as adjunctive therapy for treatment of cholera diarrhea.
Assuntos
Toxina da Cólera/metabolismo , Gangliosídeos/metabolismo , Mucosa Intestinal/metabolismo , Lactoferrina/metabolismo , Animais , Bovinos , Cloretos/farmacologia , Relação Dose-Resposta a Droga , Enterotoxinas/biossíntese , Escherichia coli/efeitos dos fármacos , Escherichia coli/crescimento & desenvolvimento , Escherichia coli/metabolismo , Feminino , Compostos Férricos/farmacologia , Gangliosídeo G(M1)/metabolismo , Intestinos/efeitos dos fármacos , Intestinos/patologia , Lactoferrina/farmacologia , Camundongos , Ligação Proteica/efeitos dos fármacos , Receptores de Superfície Celular/metabolismoRESUMO
Norovirus was detected in 17.4% of 224 diarrhoeal samples from children younger than 24 months of age in Lima, in whom all common pathogens had been excluded (pathogen negative). Norovirus was identified more frequently in children older than 12 months of age than in younger children (34% vs 8%, P<0.001). Among norovirus-positive samples, genogroup II was the predominant group (92%). Compared with rotavirus, norovirus episodes tended to be of shorter duration and less severe. The role of norovirus as a cause of diarrhoea and the ascertainment of its severity in developing countries needs further confirmation by future epidemiological studies.
Assuntos
Infecções por Caliciviridae/epidemiologia , Diarreia/epidemiologia , Gastroenterite/epidemiologia , Norovirus/patogenicidade , População Suburbana/estatística & dados numéricos , Infecções por Caliciviridae/virologia , Diarreia/virologia , Feminino , Gastroenterite/virologia , Humanos , Lactente , Masculino , Norovirus/isolamento & purificação , Peru/epidemiologia , Estudos ProspectivosRESUMO
We conducted a prospective study in three hospitals in Lima in human immunodeficiency virus (HIV) children to determine the frequency of diarrheagenic Escherichia coli. Five E. coli colonies/patients were studied by a multiplex real-time polymerase chain reaction to identify the six currently recognized groups of diarrhea-associated E. coli. We have analyzed 70 HIV-associated diarrheal and 70 control samples from HIV-infected children without diarrhea. Among the diarrheal episodes 19% were persistent, 3% dysenteric, and 33% were associated with moderate or severe dehydration. The diarrheagenic E. coli were the most commonly isolated pathogens in diarrhea (19%) and control samples (26%) (P = 0.42), including enteroaggregative (6% versus 10%), enteropathogenic (6% versus 10%), and enterotoxigenic E. coli (4% versus 3%), respectively. The HIV-infected children with diarrhea had the worse age-related immunosuppression, higher viral loads, and were on highly active antiretroviral treatment (HAART) less often than HIV-infected children without diarrhea. Diarrheagenic E. coli were highly resistant to ampicillin (74%) and cotrimoxazole (70%).