Serogrupos y susceptibilidad antimicrobiana en cepas de Shigella / Serogroups and antimicrobial susceptibility in Shigella strains

Shigella spp es uno de los agentes causales más importantes de diarrea aguda en los niños. La presente investigación tuvo como objetivo conocer la frecuencia de serogrupos y la susceptibilidad antimicrobiana a los fármacos de elección y a los alternativos. MÉTODOS. Se realizó un estudio descriptivo y retrospectivo entre enero de 2004 y diciembre de 2006 a partir de 34 cepas de Shigella spp. aisladas en heces de niños menores de 5 años ingresados en el Hospital Aleida Fernández Chardiet (Municipio Güines) a causa de enfermedad diarreica aguda. RESULTADOS. Los serogrupos encontrados fueron S sonnei (70,5 por ciento) y S flexneri (29,5 por ciento). Ambos serogrupos mostraron altos niveles de resistencia al trimetoprim-sulfametoxazol y a la ampicilina, ademas en las cepas de S sonnei se encontró resistencia al ácido nalidíxico y en las de S flexneri al cloranfenicol. Todas las cepas mostraron altos porcentajes de sensibilidad a la ceftriaxona, norfloxacina y ciprofloxacina. El 70 por ciento de las cepas de S sonnei fueron multirresistentes. El patrón de multirresistencia (ampicilina, trimetoprim-sulfamtetoxazol y Acido nalidíxico) se encontró en ambos serogrupos. CONCLUSIONES. La determinación y vigilancia de los patrones de resistencia facilita el control de la política de uso de antibióticos en la región estudiada y previene el surgimiento de cepas resistentes a fármacos de nueva generación.

Shigella ssp. is one of the more important causal agents of acute diarrhea in children. Present research has as aim to know serogroups frequency and antimicrobial susceptibility to choice drugs, and to its alternatives. METHODS: A descriptive retrospective study was carried out between January 2004 and December 2006 of 34 strains of Shigella isolated from children lower than 5 years admitted in Aleida Fernßndez Chardiet Hospital in Güines Municipality by acute diarrheic disease. RESULTS: Serogroups included S sonnei (70,5 percent), and S flexeneri (29,5 percent). Both serogroups showed high levels of resistance to Trimethoprim-Sulfamethoxaxole and to Ampicillin and to in strains of S sonnei there was resistance to nalidixic acid, and in that of S flexeneri, to Chloramphenicol. All strains showed high percentages of sensibility to Cephtriaxone, Norphloxacine, and to Cyprophloxacine. The 70 percent of strains of S sonnei were multi-resistant. Multiresistance pattern (Ampicillin, Trimetroprim-Sulfamethoxaxole and nalidixic acid) was present in both serogroups. Assessment and surveillance of resistance patterns allow control of policy on use of antibiotics in study region, and to foresee rise of strains resistant to new generation-drugs.

Antibody response to outer membrane proteins in Shigella dysenteriae type 1 infection with special reference to appearance of murine antibodies.

In shigellosis, the protective immune mechanism is not well established. The bacterial outer membrane proteins (OMPs) may have a role in the induction of immunity due to their outwardly location. The serum antibody response of S. dysenteriae type 1 infected patients against OMPs was assessed by enzyme linked immunosorbent assay (ELISA). A striking elevation of serum IgG response was noted during the convalescent phase. Murine antiserum directed against S. dysenteriae 1 OMPs was found to be highly cross reactive with the OMPs isolated from heterologous species. A major antigenic OMP was partially purified and showed distinct immunodominance in ELISA. These observations suggest that the specific component may have some immunoprophylactic potential.

Immunoblot analysis of antibody responses to Shigella dysenteriae type 1 infection.

Immunoblot analysis was used to identify the antigenic components of the outer membrane protein (OMP) extract from Sh. dysenteriae type 1 that may be relevant in protection against infection. The OMPs were extracted by ultrasonic disruption followed by Sarkosyl extraction. The macromolecular bands were separated by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE), electroeluted to a nitrocellulose matrix and complexed with peroxidase conjugated antibodies in human convalescent sera. IgG specific reaction was found to a major antigenic component at 57 kilodaltons. In addition, weakly reactive three antigenic determinants of greater than 57 kD and four of less than 57 kD were found. Control sera from a rabbit immunized against OMP also exhibited a similar pattern of antigenic reactivity. Some of the OMPs with high antigenicity may be important in immunoprophylaxis.