Salmonela

Clasificación

Características Generales

Salmonella Salmonella Salmonellae are gram-negative bacilli of the family Enterobacteriaceae. Salmonellae are flagellated, non-lactose-fermenting, and hydrogen sulfide-producing microbes. Salmonella enterica, the most common disease-causing species in humans, is further classified based on serotype as typhoidal (S. typhi and paratyphi) and nontyphoidal (S. enteritidis and typhimurium). Salmonella spp.

• Características:
  • Tinción de Gram y estructura: bacilos gramnegativos
  • Motilidad: móvil y flagelada
  • Microbios no fermentadores de lactosa; fermentan glucosa y manosa
  • Bacilos oxidasa negativos
  • Inactivado por ácidos
  • Capacidad de producir sulfuro de hidrógeno (H₂S)
  • Medio de crecimiento:
    • Eosina azul de metileno, MacConkey o medio de desoxicolato utilizado para detectar microbios que no fermentan la lactosa
    • Selectivo para Salmonella-Shigella ( SS SS Scleroderma (systemic sclerosis) is an autoimmune condition characterized by diffuse collagen deposition and fibrosis. The clinical presentation varies from limited skin involvement to diffuse involvement of internal organs. Scleroderma): agar hektoen entérico (HE), agar SS SS Scleroderma (systemic sclerosis) is an autoimmune condition characterized by diffuse collagen deposition and fibrosis. The clinical presentation varies from limited skin involvement to diffuse involvement of internal organs. Scleroderma
• Enfermedades asociadas: fiebre tifoidea, gastroenteritis Gastroenteritis Gastroenteritis is inflammation of the stomach and intestines, commonly caused by infections from bacteria, viruses, or parasites. Transmission may be foodborne, fecal-oral, or through animal contact. Common clinical features include abdominal pain, diarrhea, vomiting, fever, and dehydration. Gastroenteritis/ enterocolitis Enterocolitis Inflammation of the mucosa of both the small intestine and the large intestine. Etiology includes ischemia, infections, allergic, and immune responses. Yersinia spp./Yersiniosis, bacteriemia

Especies clínicamente relevantes

Salmonella enterica Salmonella enterica A subgenus of Salmonella containing several medically important serotypes. The habitat for the majority of strains is warm-blooded animals. Salmonella es la especie principal y tiene los LOS Neisseria siguientes serotipos:

• Tifoidea (serotipos que causan fiebre tifoidea o fiebre entérica):
  • S. enterica serotipo typhi (anteriormente S. typhi)
  • S. paratyphi
• No tifoidea (todos los LOS Neisseria demás serotipos asociados con gastroenteritis Gastroenteritis Gastroenteritis is inflammation of the stomach and intestines, commonly caused by infections from bacteria, viruses, or parasites. Transmission may be foodborne, fecal-oral, or through animal contact. Common clinical features include abdominal pain, diarrhea, vomiting, fever, and dehydration. Gastroenteritis transmitida por alimentos, más común en EN Erythema nodosum is an immune-mediated panniculitis (inflammation of the subcutaneous fat) caused by a type IV (delayed-type) hypersensitivity reaction. It commonly manifests in young women as tender, erythematous nodules on the shins. Erythema Nodosum los LOS Neisseria Estados Unidos):
  • S. enteritidis S. enteritidis A serotype of Salmonella enterica which is an etiologic agent of gastroenteritis in man and other animals. Salmonella
  • S. typhimurium

Patogénesis

Transmisión y virulencia

• Reservorios:
  • Tifoidea: tracto gastrointestinal humano
  • No tifoideo:
    • Animales de granja: aves, ganado vacuno y cerdos
    • Mascotas: tortugas, loros, roedores, gatos y perros
• Transmisión:
  • Vía fecal-oral
  • Ingestión de productos alimenticios (comúnmente alimentos contaminados o poco cocidos, incluidos aves y huevos)
  • Dosis infectante de la infección por S. enterica:
    • Varía con el serotipo
    • Considerablemente mayor que la Shigella Shigella Shigella is a genus of gram-negative, non-lactose-fermenting facultative intracellular bacilli. Infection spreads most commonly via person-to-person contact or through contaminated food and water. Humans are the only known reservoir. Shigella (la transmisión de persona a persona por contacto directo es poco probable)
  • S. enterica es inactivada por ácidos. Los LOS Neisseria inóculos más pequeños pueden infectar a personas que toman antiácidos o pacientes con aclorhidria.
• Virulencia:
  • Antígeno del polisacárido capsular Vi:
    • Polisacárido de superficie en EN Erythema nodosum is an immune-mediated panniculitis (inflammation of the subcutaneous fat) caused by a type IV (delayed-type) hypersensitivity reaction. It commonly manifests in young women as tender, erythematous nodules on the shins. Erythema Nodosum Salmonella Salmonella Salmonellae are gram-negative bacilli of the family Enterobacteriaceae. Salmonellae are flagellated, non-lactose-fermenting, and hydrogen sulfide-producing microbes. Salmonella enterica, the most common disease-causing species in humans, is further classified based on serotype as typhoidal (S. typhi and paratyphi) and nontyphoidal (S. enteritidis and typhimurium). Salmonella typhi
    • Interfiere con la fagocitosis
  • Antígeno H (flagelar): necesario para la motilidad
  • Antígeno O (lipopolisacárido): produce colonias lisas en EN Erythema nodosum is an immune-mediated panniculitis (inflammation of the subcutaneous fat) caused by a type IV (delayed-type) hypersensitivity reaction. It commonly manifests in young women as tender, erythematous nodules on the shins. Erythema Nodosum agar
  • Pili Pili Filamentous or elongated proteinaceous structures which extend from the cell surface in gram-negative bacteria that contain certain types of conjugative plasmid. These pili are the organs associated with genetic transfer and have essential roles in conjugation. Normally, only one or a few pili occur on a given donor cell. This preferred use of ‘pili’ refers to the sexual appendage, to be distinguished from bacterial fimbriae, also known as common pili, which are usually concerned with adhesion. Salmonella:
    • Se une a los LOS Neisseria receptores de D-manosa en EN Erythema nodosum is an immune-mediated panniculitis (inflammation of the subcutaneous fat) caused by a type IV (delayed-type) hypersensitivity reaction. It commonly manifests in young women as tender, erythematous nodules on the shins. Erythema Nodosum los LOS Neisseria tipos de células eucariotas
    • Similar a Escherichia coli Escherichia coli The gram-negative bacterium Escherichia coli is a key component of the human gut microbiota. Most strains of E. coli are avirulent, but occasionally they escape the GI tract, infecting the urinary tract and other sites. Less common strains of E. coli are able to cause disease within the GI tract, most commonly presenting as abdominal pain and diarrhea. Escherichia coli tipo 1 pili Pili Filamentous or elongated proteinaceous structures which extend from the cell surface in gram-negative bacteria that contain certain types of conjugative plasmid. These pili are the organs associated with genetic transfer and have essential roles in conjugation. Normally, only one or a few pili occur on a given donor cell. This preferred use of ‘pili’ refers to the sexual appendage, to be distinguished from bacterial fimbriae, also known as common pili, which are usually concerned with adhesion. Salmonella en EN Erythema nodosum is an immune-mediated panniculitis (inflammation of the subcutaneous fat) caused by a type IV (delayed-type) hypersensitivity reaction. It commonly manifests in young women as tender, erythematous nodules on the shins. Erythema Nodosum función y morfología

Historia natural de la enfermedad

• Entra a los LOS Neisseria humanos por ingestión:
  • Algunos organismos sobreviven a la exposición al AL Amyloidosis ácido gástrico → intestino delgado
  • Desde el lumen, laa Salmonella Salmonella Salmonellae are gram-negative bacilli of the family Enterobacteriaceae. Salmonellae are flagellated, non-lactose-fermenting, and hydrogen sulfide-producing microbes. Salmonella enterica, the most common disease-causing species in humans, is further classified based on serotype as typhoidal (S. typhi and paratyphi) and nontyphoidal (S. enteritidis and typhimurium). Salmonella spp., mediada por sus pili Pili Filamentous or elongated proteinaceous structures which extend from the cell surface in gram-negative bacteria that contain certain types of conjugative plasmid. These pili are the organs associated with genetic transfer and have essential roles in conjugation. Normally, only one or a few pili occur on a given donor cell. This preferred use of ‘pili’ refers to the sexual appendage, to be distinguished from bacterial fimbriae, also known as common pili, which are usually concerned with adhesion. Salmonella, puede:
    • Penetrar las células M (micropliegues) de las placas de Peyer (sistema linfoide asociado al AL Amyloidosis intestino)
    • Penetrar las células epiteliales del intestino
• En EN Erythema nodosum is an immune-mediated panniculitis (inflammation of the subcutaneous fat) caused by a type IV (delayed-type) hypersensitivity reaction. It commonly manifests in young women as tender, erythematous nodules on the shins. Erythema Nodosum el intestino:
  • Los LOS Neisseria organismos proliferan → hiperplasia e inflamación de las placas de Peyer (fiebre, síntomas abdominales)
  • La Salmonella Salmonella Salmonellae are gram-negative bacilli of the family Enterobacteriaceae. Salmonellae are flagellated, non-lactose-fermenting, and hydrogen sulfide-producing microbes. Salmonella enterica, the most common disease-causing species in humans, is further classified based on serotype as typhoidal (S. typhi and paratyphi) and nontyphoidal (S. enteritidis and typhimurium). Salmonella spp. profundiza en EN Erythema nodosum is an immune-mediated panniculitis (inflammation of the subcutaneous fat) caused by a type IV (delayed-type) hypersensitivity reaction. It commonly manifests in young women as tender, erythematous nodules on the shins. Erythema Nodosum la lámina propia.
  • La proliferación conduce a:
    • Mayor invasión y reclutamiento de células mononucleares y linfocitos → puede causar ulceraciones
    • Alteración del transporte de sodio y cloruro entre las células y la luz intestinal → diarrea
• En EN Erythema nodosum is an immune-mediated panniculitis (inflammation of the subcutaneous fat) caused by a type IV (delayed-type) hypersensitivity reaction. It commonly manifests in young women as tender, erythematous nodules on the shins. Erythema Nodosum casos severos:
  • La replicación persiste en EN Erythema nodosum is an immune-mediated panniculitis (inflammation of the subcutaneous fat) caused by a type IV (delayed-type) hypersensitivity reaction. It commonly manifests in young women as tender, erythematous nodules on the shins. Erythema Nodosum el sistema reticuloendotelial → hepatoesplenomegalia
  • Los LOS Neisseria patógenos invasores ingresan al AL Amyloidosis torrente sanguíneo → sepsis Sepsis Systemic inflammatory response syndrome with a proven or suspected infectious etiology. When sepsis is associated with organ dysfunction distant from the site of infection, it is called severe sepsis. When sepsis is accompanied by hypotension despite adequate fluid infusion, it is called septic shock. Sepsis and Septic Shock

Enfermedades Causadas por Salmonella

Especies tifoideas ( Salmonella Salmonella Salmonellae are gram-negative bacilli of the family Enterobacteriaceae. Salmonellae are flagellated, non-lactose-fermenting, and hydrogen sulfide-producing microbes. Salmonella enterica, the most common disease-causing species in humans, is further classified based on serotype as typhoidal (S. typhi and paratyphi) and nontyphoidal (S. enteritidis and typhimurium). Salmonella typhi y paratyphi)

Fiebre tifoidea o fiebre entérica:

• Descripción:
  • Enfermedad sistémica grave en EN Erythema nodosum is an immune-mediated panniculitis (inflammation of the subcutaneous fat) caused by a type IV (delayed-type) hypersensitivity reaction. It commonly manifests in young women as tender, erythematous nodules on the shins. Erythema Nodosum la que las bacterias entran en EN Erythema nodosum is an immune-mediated panniculitis (inflammation of the subcutaneous fat) caused by a type IV (delayed-type) hypersensitivity reaction. It commonly manifests in young women as tender, erythematous nodules on the shins. Erythema Nodosum el torrente sanguíneo y se diseminan en EN Erythema nodosum is an immune-mediated panniculitis (inflammation of the subcutaneous fat) caused by a type IV (delayed-type) hypersensitivity reaction. It commonly manifests in young women as tender, erythematous nodules on the shins. Erythema Nodosum los LOS Neisseria órganos y el tejido linfoide
  • Más común en EN Erythema nodosum is an immune-mediated panniculitis (inflammation of the subcutaneous fat) caused by a type IV (delayed-type) hypersensitivity reaction. It commonly manifests in young women as tender, erythematous nodules on the shins. Erythema Nodosum:
    • Niños, adultos jóvenes
    • Regiones empobrecidas
    • Viajeros (a áreas endémicas)
• Curso de la enfermedad:
  • 1ra semana:
    • Fiebre que sube gradualmente
    • Bradicardia relativa
    • Disociación pulso-temperatura
    • Estreñimiento
  • 2da semana:
    • Fiebre persistente
    • Dolor Dolor Inflammation abdominal (diarrea o estreñimiento)
    • Manchas rosadas: máculas color salmón (tronco)
  • 3ra semana:
    • Hiperplasia linfática ileocecal de la placa de Peyer (puede provocar perforación)
    • Peritonitis Peritonitis Inflammation of the peritoneum lining the abdominal cavity as the result of infectious, autoimmune, or chemical processes. Primary peritonitis is due to infection of the peritoneal cavity via hematogenous or lymphatic spread and without intra-abdominal source. Secondary peritonitis arises from the abdominal cavity itself through rupture or abscess of intra-abdominal organs. Penetrating Abdominal Injury
    • Bacteriemia
    • Hemorragia intestinal
    • Hepatoesplenomegalia
    • Estado mental alterado (encefalopatía tóxica)
  • Si no hay complicaciones, los LOS Neisseria síntomas se resuelven en EN Erythema nodosum is an immune-mediated panniculitis (inflammation of the subcutaneous fat) caused by a type IV (delayed-type) hypersensitivity reaction. It commonly manifests in young women as tender, erythematous nodules on the shins. Erythema Nodosum semanas.
• Tratamiento:
  • Fluoroquinolonas (verifique la susceptibilidad, ya que la resistencia es una posibilidad)
  • Otras opciones: azitromicina o cefalosporinas de 3ra generación
  • En EN Erythema nodosum is an immune-mediated panniculitis (inflammation of the subcutaneous fat) caused by a type IV (delayed-type) hypersensitivity reaction. It commonly manifests in young women as tender, erythematous nodules on the shins. Erythema Nodosum enfermedad sistémica grave (e.g., delirio, estupor): adición de dexametasona

Estado de portador crónico:

• Descripción:
  • Excreción de Salmonella Salmonella Salmonellae are gram-negative bacilli of the family Enterobacteriaceae. Salmonellae are flagellated, non-lactose-fermenting, and hydrogen sulfide-producing microbes. Salmonella enterica, the most common disease-causing species in humans, is further classified based on serotype as typhoidal (S. typhi and paratyphi) and nontyphoidal (S. enteritidis and typhimurium). Salmonella en EN Erythema nodosum is an immune-mediated panniculitis (inflammation of the subcutaneous fat) caused by a type IV (delayed-type) hypersensitivity reaction. It commonly manifests in young women as tender, erythematous nodules on the shins. Erythema Nodosum heces u orina > 12 meses después de la infección
  • Más frecuente en EN Erythema nodosum is an immune-mediated panniculitis (inflammation of the subcutaneous fat) caused by a type IV (delayed-type) hypersensitivity reaction. It commonly manifests in young women as tender, erythematous nodules on the shins. Erythema Nodosum:
    • Mujeres
    • Pacientes con colelitiasis/enfermedad del tracto biliar (puede ↑ riesgo de cáncer de vesícula biliar)
    • Pacientes con anomalías del tracto urinario o infección de la vejiga por Schistosoma Schistosoma Schistosomiasis is an infection caused by Schistosoma, a trematode. Schistosomiasis occurs in developing countries with poor sanitation. Freshwater snails are the intermediate host and are transmitted to humans through skin contact with contaminated fresh water. The clinical presentation occurs as a result of the host’s immune response to antigens from the eggs. Schistosoma/Schistosomiasis (raro)
• Curso de la enfermedad:
  • Portadores asintomáticos
  • Los LOS Neisseria portadores pueden transmitir bacterias en EN Erythema nodosum is an immune-mediated panniculitis (inflammation of the subcutaneous fat) caused by a type IV (delayed-type) hypersensitivity reaction. It commonly manifests in young women as tender, erythematous nodules on the shins. Erythema Nodosum casos de lavado de manos inadecuado.
  • Alto riesgo de transmisión a través de los LOS Neisseria alimentos (e.g., Mary Mallon o “Mari Tifoidea”)
• Tratamiento:
  • Fluoroquinolona durante 4 semanas (si es susceptible)
  • Evidencia limitada con amoxicilina y trimetoprim-sulfametoxazol
  • Colecistectomía en EN Erythema nodosum is an immune-mediated panniculitis (inflammation of the subcutaneous fat) caused by a type IV (delayed-type) hypersensitivity reaction. It commonly manifests in young women as tender, erythematous nodules on the shins. Erythema Nodosum algunos casos

Especies no tifoideas ( Salmonella Salmonella Salmonellae are gram-negative bacilli of the family Enterobacteriaceae. Salmonellae are flagellated, non-lactose-fermenting, and hydrogen sulfide-producing microbes. Salmonella enterica, the most common disease-causing species in humans, is further classified based on serotype as typhoidal (S. typhi and paratyphi) and nontyphoidal (S. enteritidis and typhimurium). Salmonella enteritidis y typhimurium)

Enterocolitis Enterocolitis Inflammation of the mucosa of both the small intestine and the large intestine. Etiology includes ischemia, infections, allergic, and immune responses. Yersinia spp./Yersiniosis/ gastroenteritis Gastroenteritis Gastroenteritis is inflammation of the stomach and intestines, commonly caused by infections from bacteria, viruses, or parasites. Transmission may be foodborne, fecal-oral, or through animal contact. Common clinical features include abdominal pain, diarrhea, vomiting, fever, and dehydration. Gastroenteritis:

• Descripción:
  • Presentación más común de la infección por Salmonella Salmonella Salmonellae are gram-negative bacilli of the family Enterobacteriaceae. Salmonellae are flagellated, non-lactose-fermenting, and hydrogen sulfide-producing microbes. Salmonella enterica, the most common disease-causing species in humans, is further classified based on serotype as typhoidal (S. typhi and paratyphi) and nontyphoidal (S. enteritidis and typhimurium). Salmonella
  • Ocurre más comúnmente en EN Erythema nodosum is an immune-mediated panniculitis (inflammation of the subcutaneous fat) caused by a type IV (delayed-type) hypersensitivity reaction. It commonly manifests in young women as tender, erythematous nodules on the shins. Erythema Nodosum:
    • Consumo de aves de corral, huevos y derivados del huevo (salmonelas transmitidas del pollo a los LOS Neisseria huevos por vía transovárica)
    • Consumo de agua, carne y otros productos alimenticios contaminados
    • El contacto con reservorios animales (especialmente mascotas) también aumenta el riesgo.
• Curso de la enfermedad:
  • De 8–72 horas después de la exposición:
    • Náuseas, vómitos, fiebre
    • Dolor Dolor Inflammation abdominal y diarrea
    • ↑ Dosis ingerida de bacterias: ↑ gravedad y duración de la enfermedad
  • La fiebre se resuelve al AL Amyloidosis 3er día.
  • La diarrea puede tardar hasta 10 días en EN Erythema nodosum is an immune-mediated panniculitis (inflammation of the subcutaneous fat) caused by a type IV (delayed-type) hypersensitivity reaction. It commonly manifests in young women as tender, erythematous nodules on the shins. Erythema Nodosum desaparecer.
  • El estado de portador crónico es raro (pero puede ocurrir en EN Erythema nodosum is an immune-mediated panniculitis (inflammation of the subcutaneous fat) caused by a type IV (delayed-type) hypersensitivity reaction. It commonly manifests in young women as tender, erythematous nodules on the shins. Erythema Nodosum pacientes con cálculos biliares).
• Tratamiento:
  • Hidratación y reposición de electrolitos.
  • Para síntomas leves y pacientes inmunocompetentes: no se utilizan antibióticos, la enfermedad es autolimitada
  • Para enfermedades graves (e.g., diarrea 9–10 veces al AL Amyloidosis día) y/o personas inmunocomprometidas:
    • Fluoroquinolonas (precaución en EN Erythema nodosum is an immune-mediated panniculitis (inflammation of the subcutaneous fat) caused by a type IV (delayed-type) hypersensitivity reaction. It commonly manifests in young women as tender, erythematous nodules on the shins. Erythema Nodosum niños, puede resultar en EN Erythema nodosum is an immune-mediated panniculitis (inflammation of the subcutaneous fat) caused by a type IV (delayed-type) hypersensitivity reaction. It commonly manifests in young women as tender, erythematous nodules on the shins. Erythema Nodosum anomalías del cartílago)
    • Otras opciones: trimetoprim-sulfametoxazol, azitromicina, cefalosporinas de 3ra generación
  • Para portadores crónicos:
    • 4–6 semanas de antibióticos
    • Colecistectomía en EN Erythema nodosum is an immune-mediated panniculitis (inflammation of the subcutaneous fat) caused by a type IV (delayed-type) hypersensitivity reaction. It commonly manifests in young women as tender, erythematous nodules on the shins. Erythema Nodosum algunos casos

Bacteriemia:

• Descripción:
  • < 1% de gastroenteritis Gastroenteritis Gastroenteritis is inflammation of the stomach and intestines, commonly caused by infections from bacteria, viruses, or parasites. Transmission may be foodborne, fecal-oral, or through animal contact. Common clinical features include abdominal pain, diarrhea, vomiting, fever, and dehydration. Gastroenteritis por Salmonella Salmonella Salmonellae are gram-negative bacilli of the family Enterobacteriaceae. Salmonellae are flagellated, non-lactose-fermenting, and hydrogen sulfide-producing microbes. Salmonella enterica, the most common disease-causing species in humans, is further classified based on serotype as typhoidal (S. typhi and paratyphi) and nontyphoidal (S. enteritidis and typhimurium). Salmonella, con la mayoría de los LOS Neisseria casos de bacteriemia en EN Erythema nodosum is an immune-mediated panniculitis (inflammation of the subcutaneous fat) caused by a type IV (delayed-type) hypersensitivity reaction. It commonly manifests in young women as tender, erythematous nodules on the shins. Erythema Nodosum individuos < 5 años de edad
  • Involucra especies más invasoras (como los LOS Neisseria serotipos choleraesuis, heidelberg)
  • Más común en EN Erythema nodosum is an immune-mediated panniculitis (inflammation of the subcutaneous fat) caused by a type IV (delayed-type) hypersensitivity reaction. It commonly manifests in young women as tender, erythematous nodules on the shins. Erythema Nodosum:
    • Pacientes inmunocomprometidos
    • Infantes y ancianos
    • Hemoglobinopatías
    • Esquistosomiasis, paludismo
    • Enfermedad granulomatosa crónica
• Curso de la enfermedad:
  • Puede incluir artritis séptica, endocarditis Endocarditis Endocarditis is an inflammatory disease involving the inner lining (endometrium) of the heart, most commonly affecting the cardiac valves. Both infectious and noninfectious etiologies lead to vegetations on the valve leaflets. Patients may present with nonspecific symptoms such as fever and fatigue. Endocarditis, osteomielitis y meningitis Meningitis Meningitis is inflammation of the meninges, the protective membranes of the brain, and spinal cord. The causes of meningitis are varied, with the most common being bacterial or viral infection. The classic presentation of meningitis is a triad of fever, altered mental status, and nuchal rigidity. Meningitis
  • Infección endovascular (más común en EN Erythema nodosum is an immune-mediated panniculitis (inflammation of the subcutaneous fat) caused by a type IV (delayed-type) hypersensitivity reaction. It commonly manifests in young women as tender, erythematous nodules on the shins. Erythema Nodosum la aorta Aorta The main trunk of the systemic arteries. Mediastinum and Great Vessels: Anatomy abdominal):
    • Complicación rara pero grave
    • Causa aneurismas y placas ateroscleróticas.
• Tratamiento (curso más largo):
  • Fluoroquinolonas
  • Alternativas: cefalosporinas de 3ra generación, trimetoprim-sulfametoxazol, ampicilina

Comparación con Shigela

Tanto la Salmonella Salmonella Salmonellae are gram-negative bacilli of the family Enterobacteriaceae. Salmonellae are flagellated, non-lactose-fermenting, and hydrogen sulfide-producing microbes. Salmonella enterica, the most common disease-causing species in humans, is further classified based on serotype as typhoidal (S. typhi and paratyphi) and nontyphoidal (S. enteritidis and typhimurium). Salmonella como la Shigella Shigella Shigella is a genus of gram-negative, non-lactose-fermenting facultative intracellular bacilli. Infection spreads most commonly via person-to-person contact or through contaminated food and water. Humans are the only known reservoir. Shigella pueden invadir el tracto gastrointestinal y causar diarrea.