Historical, current, and emerging tools for identification and serotyping of Shigella.

The Shigella genus includes serious foodborne disease etiologic agents, with 4 species and 54 serotypes. Identification at species and serotype levels is a crucial task in microbiological laboratories. Nevertheless, the genetic similarity between Shigella spp. and Escherichia coli challenges the correct identification and serotyping of Shigella spp., with subsequent negative repercussions on surveillance, epidemiological investigations, and selection of appropriate treatments. For this purpose, multiple techniques have been developed historically ranging from phenotype-based methods and single or multilocus molecular techniques to whole-genome sequencing (WGS). To facilitate the selection of the most relevant method, we herein provide a global overview of historical and emerging identification and serotyping techniques with a particular focus on the WGS-based approaches. This review highlights the excellent discriminatory power of WGS to more accurately elucidate the epidemiology of Shigella spp., disclose novel promising genomic targets for surveillance methods, and validate previous well-established methods.

Enterobacterial repetitive intergenic consensus (ERIC)-PCR analysis as a reliable evidence for suspected Shigella spp. outbreaks

Abstract Background Shigellosis remains a serious public health problem and an important cause of morbidity and mortality worldwide. The aim of this study was to characterize fliC and the genetic relatedness of Shigella spp. isolated during a one-year period from children in a suspected outbreak in Tehran, Iran. Methods and results Fifty Shigella spp. were isolated from 3779 stool samples of children with diarrhea (prevalence rate: 1.32%). Among the isolates, 92% were characterized as Shigella sonnei, while 6% and 2% were identified as S. flexneri and S. boydii, respectively. S. dysenteriae was not recovered from the patients. All isolates were negative for fliC except for Shigella standard strains. The enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR) profiles allowed differentiating the 50 isolates into 5 ERIC types, which were grouped into five clusters (ET1-ET5). Computer-assisted clustering of the strains showed a high degree of similarity among the isolates. Conclusion In conclusion, given the clonal correlation of the Shigella strains isolated in this study and the lack of fliC among them, we propose that probably a single or limited fliC-defected Shigella clone spread and caused the outbreak.

Enterobacterial repetitive intergenic consensus (ERIC)-PCR analysis as a reliable evidence for suspected Shigella spp. outbreaks

Background: Shigellosis remains a serious public health problem and an important cause of morbidity and mortality worldwide. The aim of this study was to characterize fliC and the genetic relatedness of Shigella spp. isolated during a one-year period from children in a suspected outbreak in Tehran, Iran. Methods and results: Fifty Shigella spp. were isolated from 3779 stool samples of children with diarrhea (prevalence rate: 1.32%). Among the isolates, 92% were characterized as Shigella sonnei, while 6% and 2% were identified as S. flexneri and S. boydii, respectively. S. dysenteriae was not recovered from the patients. All isolates were negative for fliC except for Shigella standard strains. The enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR) profiles allowed differentiating the 50 isolates into 5 ERIC types, which were grouped into five clusters (ET1-ET5). Computer-assisted clustering of the strains showed a high degree of similarity among the isolates. Conclusion: In conclusion, given the clonal correlation of the Shigella strains isolated in this study and the lack of fliC among them, we propose that probably a single or limited fliC-defected Shigella clone spread and caused the outbreak.(AU)

Enterobacterial repetitive intergenic consensus (ERIC)-PCR analysis as a reliable evidence for suspected Shigella spp. outbreaks.

BACKGROUND: Shigellosis remains a serious public health problem and an important cause of morbidity and mortality worldwide. The aim of this study was to characterize fliC and the genetic relatedness of Shigella spp. isolated during a one-year period from children in a suspected outbreak in Tehran, Iran. METHODS AND RESULTS: Fifty Shigella spp. were isolated from 3779 stool samples of children with diarrhea (prevalence rate: 1.32%). Among the isolates, 92% were characterized as Shigella sonnei, while 6% and 2% were identified as S. flexneri and S. boydii, respectively. S. dysenteriae was not recovered from the patients. All isolates were negative for fliC except for Shigella standard strains. The enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR) profiles allowed differentiating the 50 isolates into 5 ERIC types, which were grouped into five clusters (ET1-ET5). Computer-assisted clustering of the strains showed a high degree of similarity among the isolates. CONCLUSION: In conclusion, given the clonal correlation of the Shigella strains isolated in this study and the lack of fliC among them, we propose that probably a single or limited fliC-defected Shigella clone spread and caused the outbreak.

Isolamento e determinação de sensibilidade e resistência a antimicrobianos de cepas bacterianas presentes na cloaca de Trachemys scripta elegans (Wied, 1839) criadas em cativeiro em Petrolina, PE / Isolation and determination of antimicrobials sensitivity and resistance of bacterial strains present in the cloaca Trachemys scripta elegans (Wied, 1839) raised in captivity in Petrolina/PE, Brazil

Este estudo isolou e determinou o perfil de sensibilidade e de resistência a antimicrobianos de cepas bacterianas isoladas da cloaca de Trachemys scripta elegans (T. s. elegans) criadas em cativeiro. Após 120 dias de adaptação, amostras de swab cloacal obtidas de 20 animais adultos foram cultivadas e, após a identificação dos patógenos através de testes bioquímicos, submetidas ao teste de suscetibilidade a nove antimicrobianos. Enterobacter aerogenes (85%); Shigella spp. (10%) e Edwadsiella spp. (5%) foram isolados e identificados. Os isolados de E. aerogenes foram sensíveis à gentamicina (86%), enrofloxacina (79%), estreptomicina (50%), sulfazotrim (36%) e ampicilina (29%) e resistentes a penicilina (100%), eritromicina (93%), cefalexina (86%) ampicilina (71%) e sulfazotrim (64%). Isolados de Shigella spp. apresentaram sensibilidade à gentamicina (100%), enrofloxacina (50%), doxicilina (50%), estreptomicina (50%), ampicilina (50%), penicilina (50%) e sulfazotrim (50%) e resistência a doxicilina (50%), estreptomicina (50%), ampicilina (50%), penicilina (100%), cefalexina (50%) e sulfazotrim (50%), enquanto que os de Edwardsiella spp. foram sensíveis apenas à gentamicina (100%) e altamente resistentes (100%) aos demais antimicrobianos. Os resultados sugerem a participação de T. s. elegans na cadeia epidemiológica, como reservatório de patógenos importantes, como E. aerogenes, Shigella spp. e Edwardisiella spp., tornando importante a adoção de medidas preventivas pelo risco zoonótico que apresentam e corretas de tratamento e de controle em cativeiros e domicílios, assim como de estudos que enfoquem as características de sensibilidade e de resistência antimicrobiana dos isolados cloacais, pois a multirresistência a drogas pode ser transmitida aos humanos e comprometer o tratamento de indivíduos com doenças graves.(AU)

This study isolated and determined the profile of susceptibility and antimicrobials resistance of bacterial strains isolated from the cloaca Trachemys scripta elegans (T. s. elegans) raised in captivity. After 120 days of adaptation, cloacal swab samples obtained from 20 adults animals were grown and, after the pathogens identification through biochemical tests, submitted to the test of susceptibility to nine antimicrobials. Enterobacter aerogenes (85%); Shigella spp. (10%) and Edwadsiella spp. (5%) were isolated and identified. Isolates from E. aerogenes were sensitive to gentamicin (86%), enrofloxacin (79%), streptomycin (50%), sulfazotrim (36%) and ampicillin (29%) and resistant to penicillin (100%), erythromycin (93%), cephalexin (86%), ampicillin (71%) and sulfazotrim (64%). Isolates from Shigella spp. showed sensitivity to gentamicin (100%), enrofloxacin (50%), doxycycline (50%), streptomycin (50%), ampicillin (50%), penicillin (50%) and sulfazotrim (50%) and resistance to doxycycline (50 %), streptomycin (50%), ampicillin (50%), penicillin (100%), cephalexin (50%) and sulfazotrim (50%), while the Edwardsiella spp. were sensitive only to gentamicin (100%) and were highly resistant (100%) to other antibiotics. The results suggest the participation of T. s. elegans in the epidemiological chain, as reservoir of important pathogens, such as E. aerogenes, Shigella spp. and Edwardisiella spp., making it important to adopt preventive measures for zoonotic risk that present and correct treatment and control in captivity and households, as well as studies that address the sensitivity characteristics and antimicrobial resistance of isolates from cloaca, as it multidrug resistance to drugs can be transmitted to humans and compromise the treatment of patients with serious diseases.(AU)

Isolamento e determinação de sensibilidade e resistência a antimicrobianos de cepas bacterianas presentes na cloaca de Trachemys scripta elegans (Wied, 1839) criadas em cativeiro em Petrolina, PE / Isolation and determination of antimicrobials sensitivity and resistance of bacterial strains present in the cloaca Trachemys scripta elegans (Wied, 1839) raised in captivity in Petrolina/PE, Brazil

Este estudo isolou e determinou o perfil de sensibilidade e de resistência a antimicrobianos de cepas bacterianas isoladas da cloaca de Trachemys scripta elegans (T. s. elegans) criadas em cativeiro. Após 120 dias de adaptação, amostras de swab cloacal obtidas de 20 animais adultos foram cultivadas e, após a identificação dos patógenos através de testes bioquímicos, submetidas ao teste de suscetibilidade a nove antimicrobianos. Enterobacter aerogenes (85%); Shigella spp. (10%) e Edwadsiella spp. (5%) foram isolados e identificados. Os isolados de E. aerogenes foram sensíveis à gentamicina (86%), enrofloxacina (79%), estreptomicina (50%), sulfazotrim (36%) e ampicilina (29%) e resistentes a penicilina (100%), eritromicina (93%), cefalexina (86%) ampicilina (71%) e sulfazotrim (64%). Isolados de Shigella spp. apresentaram sensibilidade à gentamicina (100%), enrofloxacina (50%), doxicilina (50%), estreptomicina (50%), ampicilina (50%), penicilina (50%) e sulfazotrim (50%) e resistência a doxicilina (50%), estreptomicina (50%), ampicilina (50%), penicilina (100%), cefalexina (50%) e sulfazotrim (50%), enquanto que os de Edwardsiella spp. foram sensíveis apenas à gentamicina (100%) e altamente resistentes (100%) aos demais antimicrobianos. Os resultados sugerem a participação de T. s. elegans na cadeia epidemiológica, como reservatório de patógenos importantes, como E. aerogenes, Shigella spp. e Edwardisiella spp., tornando importante a adoção de medidas preventivas pelo risco zoonótico que apresentam e corretas de tratamento e de controle em cativeiros e domicílios, assim como de estudos que enfoquem as características de sensibilidade e de resistência antimicrobiana dos isolados cloacais, pois a multirresistência a drogas pode ser transmitida aos humanos e comprometer o tratamento de indivíduos com doenças graves.(AU)

This study isolated and determined the profile of susceptibility and antimicrobials resistance of bacterial strains isolated from the cloaca Trachemys scripta elegans (T. s. elegans) raised in captivity. After 120 days of adaptation, cloacal swab samples obtained from 20 adults animals were grown and, after the pathogens identification through biochemical tests, submitted to the test of susceptibility to nine antimicrobials. Enterobacter aerogenes (85%); Shigella spp. (10%) and Edwadsiella spp. (5%) were isolated and identified. Isolates from E. aerogenes were sensitive to gentamicin (86%), enrofloxacin (79%), streptomycin (50%), sulfazotrim (36%) and ampicillin (29%) and resistant to penicillin (100%), erythromycin (93%), cephalexin (86%), ampicillin (71%) and sulfazotrim (64%). Isolates from Shigella spp. showed sensitivity to gentamicin (100%), enrofloxacin (50%), doxycycline (50%), streptomycin (50%), ampicillin (50%), penicillin (50%) and sulfazotrim (50%) and resistance to doxycycline (50 %), streptomycin (50%), ampicillin (50%), penicillin (100%), cephalexin (50%) and sulfazotrim (50%), while the Edwardsiella spp. were sensitive only to gentamicin (100%) and were highly resistant (100%) to other antibiotics. The results suggest the participation of T. s. elegans in the epidemiological chain, as reservoir of important pathogens, such as E. aerogenes, Shigella spp. and Edwardisiella spp., making it important to adopt preventive measures for zoonotic risk that present and correct treatment and control in captivity and households, as well as studies that address the sensitivity characteristics and antimicrobial resistance of isolates from cloaca, as it multidrug resistance to drugs can be transmitted to humans and compromise the treatment of patients with serious diseases.(AU)

CTX-M extended-spectrum ß-lactamase-producing Klebsiella spp, Salmonella spp, Shigella spp and Escherichia coli isolates in Iranian hospitals

Abstract This study was conducted in Iran in order to assess the distribution of CTX-M type ESBLs producing Enterobacteriaceae. From January 2012 to December 2013, totally 198 E. coli, 139 Klebsiella spp, 54 Salmonella spp and 52 Shigella spp from seven hospitals of six provinces in Iran were screened for resistance to extended-spectrum cephalosporins. After identification and susceptibility testing, isolates presenting multiple-drug resistance (MDR) were evaluated for ESBL production by the disk combination method and by Etest using (cefotaxime and cefotaxime plus clavulanic acid). All isolates were also screened for bla CTX-M using conventional PCR. A total of 42.92%, 33.81%, 14.81% and 7.69% of the E. coli, Klebsiella spp, Salmonella spp and Shigella spp isolates were MDR, respectively. The presence of CTX-M enzyme among ESBL-producing isolates was 85.18%, 77.7%, 50%, and 66.7%, in E. coli, Klebsiella spp, Salmonella spp and Shigella spp respectively. The overall presence of CTX-M genes in Enterobacteriaceae was 15.4% and among the resistant isolates was 47.6%. This study indicated that resistance to β-lactams mediated by CTX-M enzymes in Iran had similar pattern as in other parts of the world. In order to control the spread of resistance, comprehensive studies and programs are needed.

CTX-M extended-spectrum -lactamase-producing Klebsiella spp, Salmonella spp, Shigella spp and Escherichia coli isolates in Iranian hospitals

This study was conducted in Iran in order to assess the distribution of CTX-M type ESBLs producing Enterobacteriaceae. From January 2012 to December 2013, totally 198 E. coli, 139 Klebsiella spp, 54 Salmonella spp and 52 Shigella spp from seven hospitals of six provinces in Iran were screened for resistance to extended-spectrum cephalosporins. After identification and susceptibility testing, isolates presenting multiple-drug resistance (MDR) were evaluated for ESBL production by the disk combination method and by Etest using (cefotaxime and cefotaxime plus clavulanic acid). All isolates were also screened for bla CTX-M using conventional PCR. A total of 42.92%, 33.81%, 14.81% and 7.69% of the E. coli, Klebsiella spp, Salmonella spp and Shigella spp isolates were MDR, respectively. The presence of CTX-M enzyme among ESBL-producing isolates was 85.18%, 77.7%, 50%, and 66.7%, in E. coli, Klebsiella spp, Salmonella spp and Shigella spp respectively. The overall presence of CTX-M genes in Enterobacteriaceae was 15.4% and among the resistant isolates was 47.6%. This study indicated that resistance to -lactams mediated by CTX-M enzymes in Iran had similar pattern as in other parts of the world. In order to control the spread of resistance, comprehensive studies and programs are needed.(AU)

CTX-M extended-spectrum ß-lactamase-producing Klebsiella spp, Salmonella spp, Shigella spp and Escherichia coli isolates in Iranian hospitals.

This study was conducted in Iran in order to assess the distribution of CTX-M type ESBLs producing Enterobacteriaceae. From January 2012 to December 2013, totally 198 E. coli, 139 Klebsiella spp, 54 Salmonella spp and 52 Shigella spp from seven hospitals of six provinces in Iran were screened for resistance to extended-spectrum cephalosporins. After identification and susceptibility testing, isolates presenting multiple-drug resistance (MDR) were evaluated for ESBL production by the disk combination method and by Etest using (cefotaxime and cefotaxime plus clavulanic acid). All isolates were also screened for blaCTX-M using conventional PCR. A total of 42.92%, 33.81%, 14.81% and 7.69% of the E. coli, Klebsiella spp, Salmonella spp and Shigella spp isolates were MDR, respectively. The presence of CTX-M enzyme among ESBL-producing isolates was 85.18%, 77.7%, 50%, and 66.7%, in E. coli, Klebsiella spp, Salmonella spp and Shigella spp respectively. The overall presence of CTX-M genes in Enterobacteriaceae was 15.4% and among the resistant isolates was 47.6%. This study indicated that resistance to ß-lactams mediated by CTX-M enzymes in Iran had similar pattern as in other parts of the world. In order to control the spread of resistance, comprehensive studies and programs are needed.

Recobrado de Shigella spp. conservada por la técnica de secado en perlas de vidrio / Recovery of Shigella spp. preserved on glass beads by dehydration technique

Introducción: la técnica de secado en perlas de vidrio se reporta como método de conservación microbiana desde hace varios años, pero la información existente es limitada. Con este antecedente, se decidió evaluar su utilidad para conservar bacterias, de origen clínico, en la colección de cultivos microbianos del Instituto Nacional de Higiene, Epidemiología y Microbiología. Métodos: se estudiaron dos cultivos de Shigella spp., mantenidas en refrigeración. Los datos de viabilidad obtenidos durante cuatro años de conservación fueron procesados con el paquete estadístico SPSS versión 15.0. El análisis estadístico incluyó el de la varianza para la comparación de las medias del recobrado de células viables para las variables tiempo de conservación, dilución y mezcla preservante, y el test de Scheffé de comparaciones múltiples post hoc para la discriminación de las medias. Fueron controladas las características fisiológicas y la respuesta a la tinción de Gram de las cepas. Resultados: no se encontraron diferencias significativas entre las mezclas preservantes utilizadas en este ensayo, y pudieron recobrarse ambas cepas durante los cuatro años de estudio. A partir de los seis meses se apreció una disminución del efecto protector en todas las mezclas. Se obtuvo variabilidad en algunos caracteres fisiológicos (indol, dulcitol y manitol), pero no para la respuesta a la tinción de Gram en ambas cepas, la que se mantuvo estable. Conclusiones:: el método resultó apropiado para mantener Shigella spp. por tiempo limitado, pero pudiera utilizarse como alternativa de conservación en laboratorios con limitados recursos a corto plazo, por su sencillez, bajo costo y efectividad, y debe garantizarse la disponibilidad de réplicas por otras técnicas(AU)

Introduction: glass bead dehydration technique has been reported as a microbial preservation method for some years, but the available information is limited. Based on this antecedent, it was decided to evaluate its usefulness to preserve bacteria of clinical origin in the collection of microbial cultures at the National Institute of Hygiene, Epidemiology and Microbiology. Methods: a study was conducted of two Shigella spp. cultures kept under refrigeration. The viability datas obtained during four years of preservation were processed with the statistical package SPSS, version 15.0. Statistical processing included analysis of variance for comparison of the mean recovery values of viable cells for the variables preservation time, dilution and preserving mix, and Scheffe's test of post hoc multiple comparisons for means discrimination. Physiological characteristics were controlled, as well as the response of strains to Gram stain. Results: no significant differences were found between the preserving mixes used in the trial, and both strains could be recovered during the four years of the study. The protective effect of all mixes was found to decrease after six months. Variability was obtained for some physiological characters (indol, dulcitol and mannitol), but response to Gram stain remained stable in both strains. Conclusions:: the method was found to be suitable to preserve Shigella spp. for a limited time, but it could be used as a short-term preservation alternative in laboratories with few resources, due to its simplicity, low cost and effectiveness. Availability should be ensured of replicas obtained by other techniques(AU)

Recobrado de Shigella spp. conservada por la técnica de secado en perlas de vidrio / Recovery of Shigella spp. preserved on glass beads by dehydration technique

Introducción: la técnica de secado en perlas de vidrio se reporta como método de conservación microbiana desde hace varios años, pero la información existente es limitada. Con este antecedente, se decidió evaluar su utilidad para conservar bacterias, de origen clínico, en la colección de cultivos microbianos del Instituto Nacional de Higiene, Epidemiología y Microbiología. Métodos: se estudiaron dos cultivos de Shigella spp., mantenidas en refrigeración. Los datos de viabilidad obtenidos durante cuatro años de conservación fueron procesados con el paquete estadístico SPSS versión 15.0. El análisis estadístico incluyó el de la varianza para la comparación de las medias del recobrado de células viables para las variables tiempo de conservación, dilución y mezcla preservante, y el test de Scheffé de comparaciones múltiples post hoc para la discriminación de las medias. Fueron controladas las características fisiológicas y la respuesta a la tinción de Gram de las cepas. Resultados: no se encontraron diferencias significativas entre las mezclas preservantes utilizadas en este ensayo, y pudieron recobrarse ambas cepas durante los cuatro años de estudio. A partir de los seis meses se apreció una disminución del efecto protector en todas las mezclas. Se obtuvo variabilidad en algunos caracteres fisiológicos (indol, dulcitol y manitol), pero no para la respuesta a la tinción de Gram en ambas cepas, la que se mantuvo estable. Conclusiones:: el método resultó apropiado para mantener Shigella spp. por tiempo limitado, pero pudiera utilizarse como alternativa de conservación en laboratorios con limitados recursos a corto plazo, por su sencillez, bajo costo y efectividad, y debe garantizarse la disponibilidad de réplicas por otras técnicas

Introduction: glass bead dehydration technique has been reported as a microbial preservation method for some years, but the available information is limited. Based on this antecedent, it was decided to evaluate its usefulness to preserve bacteria of clinical origin in the collection of microbial cultures at the National Institute of Hygiene, Epidemiology and Microbiology. Methods: a study was conducted of two Shigella spp. cultures kept under refrigeration. The viability datas obtained during four years of preservation were processed with the statistical package SPSS, version 15.0. Statistical processing included analysis of variance for comparison of the mean recovery values of viable cells for the variables preservation time, dilution and preserving mix, and Scheffe's test of post hoc multiple comparisons for means discrimination. Physiological characteristics were controlled, as well as the response of strains to Gram stain. Results: no significant differences were found between the preserving mixes used in the trial, and both strains could be recovered during the four years of the study. The protective effect of all mixes was found to decrease after six months. Variability was obtained for some physiological characters (indol, dulcitol and mannitol), but response to Gram stain remained stable in both strains. Conclusions:: the method was found to be suitable to preserve Shigella spp. for a limited time, but it could be used as a short-term preservation alternative in laboratories with few resources, due to its simplicity, low cost and effectiveness. Availability should be ensured of replicas obtained by other techniques

Antimicrobial Resistance of Shigella spp. isolated in the State of Pará, Brazil / Resistência Antimicrobiana de Shigella spp. isoladas no Estado do Pará

INTRODUCTION: Shigella spp. are Gram-negative, nonsporulating, rod-shaped bacteria that belong to the family Enterobacteriaceae and are responsible for shigellosis or bacillary dysentery, an important cause of worldwide morbidity and mortality. METHODS: We studied the antibiotic resistance profiles of 122 Shigella spp. strains (81 S. flexneri, 41 S. sonnei, 1 S. boydii) isolated from patients (female and male from 0 to 80 years of age) presenting diarrhea in different districts of the State of Pará, in the North of Brazil. The antibiotic resistance of the strains, isolated from human fecal samples, was determined by the diffusion disk method and by using the VITEK-2 system. RESULTS: The highest resistance rate found was the resistance rate to tetracycline (93.8 percent), followed by the resistance rate to chloramphenicol (63.9 percent) and to trimethoprim/sulfamethoxazole (63.1 percent). Resistance to at least three drugs was more common among S. flexneri than S. sonnei (39.5 percent vs. 10 percent). Six (4.9 percent) strains were susceptible to all the antibiotics tested. All strains were susceptible to cefotaxime, ceftazidime, ciprofloxacin, nalidixic acid and nitrofurantoin. CONCLUSIONS: High rates of multidrug resistance in Shigella spp. are a serious public health concern in Brazil. It is extremely important to continuously monitor the antimicrobial resistances of Shigella spp. for effective therapy and control measures against shigellosis.

INTRODUÇÃO: Shigella spp. são bactérias Gram-negativas, não esporuladas, em forma de bastonete, pertencentes a família Enterobacteriaceae responsáveis pela shigelose ou disenteria bacilar, uma importante causa de mortalidade e morbidade mundial. MÉTODOS: Foi estudado o perfil de resistência a antimicrobianos de 122 amostras de Shigella spp. (81 S. flexneri, 41 sonnei, 1 S. boydii) isoladas de pacientes (sexo feminino e masculino com faixa etária de 0 a 80 anos) com distúrbios gastrointestinais em diferentes municípios no Estado do Pará, Brasil. A resistência antimicrobiana das amostras isoladas de coprocultura, foi determinada pelo método de difusão em disco e pelo sistema Vitek II. RESULTADOS: A maior resistência foi observada em relação à tetraciclina (93,8 por cento), seguida de cloranfenicol (63,9 por cento), e trimetoprimsulfametoxazol (63,1 por cento). Multirresistência a pelo menos três antimicrobianos foi mais comum em S. flexneri comparada a S. sonnei (39,5 por cento vs. 10 por cento). Seis (4,9 por cento) amostras foram sensíveis a todos antimicrobianos testados. Todas as amostras apresentaram sensibilidade a cefotaxima, ceftazidima, ciprofloxacina, ácido nalidixico e nitrofurantoína. CONCLUSÕES: As altas taxas de multirresistência de Shigella spp. são um sério problema de saúde pública no Brasil. Sendo assim, torna-se extremamente importante um monitoramento contínuo da resistência antimicrobiana de Shigella spp. para uma terapia efetiva e medidas de controle contra shigelose.

Standardization of a quantification method for Salmonella spp. and Shigella spp. in specific liquid media / Estandarización de un método de recuento para Salmonella spp. y Shigella spp. en medios de cultivo líquidos especializados

Introduction: Chlorination is the most widely used disinfection process for drinking water production. The formation of chlorination carcinogenic by-products and chlorine intoxication by direct manipulation in small communities has motivated the study of alternative disinfection processes. In this sense, processes of advanced oxidation (PAOs) have yielded promising results. Escherichia coli (E. coli) is customarily used as faecal bacterial indicator to determine the efficiency of disinfection processes. However, it has been shown that E. coli is less resistant to disinfection than other enteric bacteria such as Shigella  spp. and Salmonella  spp. Additionally, the viable non-culturable (VNC) state yields bacteria which are not detectable on many culture media. Objective: The main objective is to standardize a method for counting Salmonella  spp. and Shigella  spp. in specific liquid media to reliably quantify the bacteriological potential risk related to disinfection processes based on PAO. Methods: The study followed a randomized bi-factorial experimental design and the Duncan multiple comparison test. This design allowed the selection of specific liquid media to fittingly standardize the counting of Salmonella  spp. and Shigella  spp. Results: We found that the best broth for counting Salmonella typhimurium strain at different concentrations in pure and mixed cultures was the Rappaport broth RP, the EE broth also allowed growing the two bacterial species tested in this research. Nonetheless, the latter results suggest the use of additional tests for this particular broth. Discussion: There was a variation in the counting results when pure cultures were used compared to those obtained from mixtures of microorganisms. It was also noted that Salmonella typhimurium and Shigella sonnei, were recovered from minimal concentrations in both RP and EE broths, respectively. To some extent, this suggests an additional confirmative method when using the EE® broth...

Introducción: La cloración es el método más usado para desinfectar aguas de consumo. La formación de subproductos cancerígenos y las intoxicaciones por manipulación directa en pequeñas comunidades, han motivado el estudio de procesos alternativos. Los procesos de oxidación avanzada (PAOS), han arrojado resultados prometedores, utilizando el indicador bacteriano Escherichia coli (E. coli), con el método recuento en placa. Sin embargo, también se ha demostrado que E. coli es menos resistente a la desinfección que otras bacterias entéricas como Shigella y Salmonella y que estos procesos generan bacterias viables que no se cultivan durante el proceso, y no se descubren en medios sólidos. Objetivo: Estandarizar un método de recuento de Salmonella sp. y Shigella sp., en medios de cultivo líquidos especializados, que permita valorar de forma confiable el riesgo bacteriológico en procesos de desinfección PAOS. Métodos: En el presente trabajo se ensayaron y seleccionaron medios líquidos especializados, con los que se estandarizó el recuento de Salmonella sp. y Shigella sp., mediante un diseño experimental aleatorizado bifactorial y la prueba de comparaciones múltiples de Duncan. Resultados: Se encontró que el mejor caldo para recuperar a S. typhimurium a diferentes concentraciones, en cultivos puros y mezclas, fue el caldo Rappaport de Merck (RP). El caldo de enriquecimiento para entero bacterias de Oxoid (EE), permitió un buen crecimiento de las dos especies objeto de esta investigación. Lo cual sugiere el empleo de pruebas adicionales cuando se use caldo EE para NMP. Discusión: Se observó una variación en el recuento cuando se usaron cultivos puros, comparado con la obtenida a partir de mezclas de microorganismos. Sin embargo, S. typhimurium. y Shigella sonnei logran ser recuperadas de concentraciones mínimas en los caldos RP, respectivamente...

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(AU)

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(AU)

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.

Characterization of Shigella spp. by antimicrobial resistance and PCR detection of ipa genes in an infantile population from Porto Velho (Western Amazon region), Brazil

The incidence of Shigella spp. was assessed in 877 infants from the public hospital in Rondônia (Western Amazon region, Brazil) where Shigella represents the fourth cause of diarrhea. Twenty-five isolates were identified: 18 were Shigella flexneri, three Shigella sonnei, three Shigella boydii and one Shigella dysenteriae. With the exception of S. dysenteriae, all Shigella spp. isolated from children with diarrhea acquired multiple antibiotic resistances. PCR detection of ipa virulence genes and invasion assays of bloody diarrhea and fever (colitis) were compared among 25 patients testing positive for Shigella. The ipaH and ipaBCD genes were detected in almost all isolates and, unsurprisingly, all Shigella isolates associated with colitis were able to invade HeLa cells. This work alerts for multiple antibiotic resistant Shigella in the region and characterizes presence of ipa virulence genes and invasion phenotypesin dysenteric shigellosis.