Pathogenic detection and molecular tracing of a bacillary dysentery outbreak by Shigella sonnei in Huainan city / 中华预防医学杂志

Objective: To understand the virulence gene and drug resistance profile of Shigella sonnei outbreak in Huainan city, and conduct pathogenic traceability analysis. Methods: Water samples and feces related to an infectious diarrhea outbreak in Huainan city in August 2020 were collected for multiple pathogen detection. Virulence gene, drug sensitivity, pulse-field gel electrophoresis and whole genome sequencing of Shigella isolates were analyzed respectively. Results: 38 strains of Shigella sonnei were detected in 56 samples of mucilage feces with a positive rate 67.86%, and all serotypes were Shigella sonnei Phase I. Three strains of Shigella sonnei were detected by fluorescence PCR in the Gram-negative (GN) bacterial enrichment solution of terminal water and well water. Virulence genes were ipaH positive (38), ipaH/ial (31) and ipaH/ial/sen positive (1), respectively. The drug resistance spectrum showed that 9 of 14 antibiotics were 100% resistant, and only imipenem, chloramphenicol, ceftazidime and ciprofloxacin were effective drugs. XbaⅠ restriction enzyme map type of 36 isolates was completely consistent, and the ST type analysis of 3 strains was ST152. Whole genome sequencing and analysis verified that the outbreak was caused by a single clonal group of strains, and revealed that the isolates of the outbreak were clustered into a large cluster with 3 Chinese strains and 1 Korean strain in the database, far away from the strains of other countries. Conclusion: The outbreak is caused by a single clone of Shigella sonnei, which are low virulence strains and have multiple drug resistance.

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.

Bacteriemia por Shigella flexneri en dos lactantes / Shigella flexneri bacteremia in children: two case report and review of literature

Resumen Shigella spp. es el aislamiento microbiológico más frecuente en las diarreas bacterianas en Argentina. Clínicamente puede causar desde una diarrea acuosa hasta disentería. En forma infrecuente causa complicaciones extraintestinales, con una incidencia de bacteriemia desde 0,4 a 7,3%; asociado a factores de riesgo como niños menores de un año de edad e inmunodeficiencias, entre otros. Presentamos los casos clínicos de dos lactantes con bacteriemia por Shigella flexneri, que consultaron por fiebre y diarrea, uno de ellos con diagnóstico de inmunodeficiencia primaria.

Shigella spp. is the most frequent micro-biological isolation in bacterial diarrhea in Argentina. It causes a watery diarrhea or dysenteric disease. It rarely causes extraintestinal problems. It has an incidence of bacteremia of 0,4-7,3%, and its appearance compels us to look for associated risk factors, as children under one year of age and immunodeficiency, among others. We describe two children with Shigella flexneri bacteremia. They presented with fever and diarrhea. One of them had primary immune deficiency.

The importance of integrons for development and propagation of resistance in Shigella: the case of Latin America

Abstract In Latin America, the disease burden of shigellosis is found to coexist with the rapid and rampant spread of resistance to commonly used antibiotics. The molecular basis of antibiotic resistance lies within genetic elements such as plasmids, transposons, integrons, genomic islands, etc., which are found in the bacterial genome. Integrons are known to acquire, exchange, and express genes within gene cassettes and it is hypothesized that they play a significant role in the transmission of multidrug resistance genes in several Gram-negative bacteria including Shigella. A few studies have described antibiotic resistance genes and integrons among multidrug resistant Shigella isolates found in Latin America. For example, in Brazil, Bolivia, Chile, Costa Rica and Peru, class 1 and class 2 integrons have been detected among multidrug resistant strains of Shigella; this phenomenon is more frequently observed in S. flexneri isolates that are resistant to trimethoprim, sulfamethoxazole, streptomycin, ampicillin, chloramphenicol, and tetracycline. The gene cassette sul2, which is frequently detected in Shigella strains resistant to the sulfonamides, suggests that the sulfonamide-resistant phenotype can be explained by the presence of the sul2 genes independent of the integron class detected. It is to be noted that sul3 was negative in all isolates analyzed in these studies.The high frequency of sulfonamide (as encoded by sul2) and trimethoprim resistance is likely to be a result of the recurrent use of trimethoprim sulfamethoxazole as a popular regimen for the treatment of shigellosis. The observed resistance profiles of Shigella strains confirm that ampicillin and trimethoprim-sulfamethoxazole are ineffective as therapeutic options. In-depth information regarding antibiotic resistance mechanism in this pathogen is needed in order to develop suitable intervention strategies. There is a pressing need for regional and local antimicrobial resistance profiling of Shigella to be included as a part of the public health strategy.

Caracterización molecular de aislamientos de Shigella sonnei recuperados en el programa de vigilancia por el laboratorio de la enfermedad diarreica aguda en Colombia / Molecular characterization of Shigella sonnei isolates recovered by the Laboratory Surveillance Program for Acute Diarrheal Disease in Colombia

Introducción. En Colombia, Shigella sonnei es uno de los serotipos más frecuentemente aislados (53,4 %) de muestras clínicas humanas asociadas a la enfermedad diarreica aguda. La identificación de patrones de restricción del ADN mediante electroforesis en gel de campo pulsado constituye la base de la vigilancia molecular de S. sonnei . Objetivo. Establecer la base de la vigilancia molecular de S. sonnei en Colombia mediante electroforesis en gel de campo pulsado. Materiales y métodos. Se estudiaron 102 de los 2.048 aislamientos de S. sonnei remitidos por la Red Nacional de Laboratorios entre 1997 y marzo del 2013; la selección se hizo de acuerdo con el patrón de resistencia antimicrobiana, el origen de la muestra y la relación con brotes. Se determinó el patrón genético mediante electroforesis en gel de campo pulsado con las enzimas de restricción XbaI y Blnl, según el protocolo de la red PulseNet International. El análisis de los patrones electroforéticos se hizo con el programa GelCompar II, versión 4.0. Resultados. Se obtuvieron 42 patrones electroforéticos con una similitud de 70 a 100 %. El patrón más frecuente fue COIN08J16X01.0017 (17,6 %), seguido por los patrones COIN04J16X01.0004 (9,8 %) y COIN02J16X01.0002 (5,8 %), y el 66,8 % restante se asoció con otros patrones electroforéticos. El análisis de brotes demostró la relación genética de cada brote con 100 % de similitud en la identificación; el patrón más frecuente en los brotes fue el COIN08J16X01.0017 (17,1 %). Conclusión. Se estableció la base de datos genotípicos de aislamientos de S. sonnei a nivel nacional mediante electroforesis en gel de campo pulsado; se incluyeron los 42 patrones únicos identificados en este estudio.

Introduction: In Colombia, Shigella sonnei is one of the most frequently isolated serotypes (53.4%) in human clinical samples associated with diarrheal acute disease. The identification of DNA restriction patterns by pulsed field gel electrophoresis is the basis for the molecular surveillance of S. sonnei . Objective: To establish the basis for the molecular surveillance of S. sonnei in Colombia using pulsed-field gel electrophoresis. Materials and methods: We studied 102 of 2,048 S. sonnei isolates referred by the National Laboratory Network between 1997 and March, 2013; the selection was made according to the antimicrobial multiresistance profile, the source of samples, and the relation to outbreaks. The genetic profile was determined by pulsed field gel electrophoresis using the restriction enzymes XbaI and BlnI in accordance with the PulseNet International protocol. The electrophoretic patterns were analyzed with the GelCompare II, version 4.0 software. Results: We obtained 42 electrophoretic patterns with a 70% to 100% similarity. The most frequent pattern was COIN08J16X01.0017 with 17.6%, followed by patterns COIN04J16X01.0004 with 9.8%, and COIN02J16X01.0002 with 5.8%, while the remaining 66.8% was associated with other electrophoretic patterns. The analysis of 10 outbreaks demonstrated their genetic relation with a 100% of similarity; the most frequent pattern in outbreaks was COIN08J16X01.0017 with 17.1%. Conclusion: The genotypic database for Shigella sonnei isolates was established using pulsed field gel electrophoresis including the 42 unique patterns identified in this study.

Manual de monitoramento da qualidade dos registros de enfermagem na assistência domiciliar / Manual de monitoreo de la calidad de los registros de enfermería en la atención domiciliaria / Manual for monitoring the quality of nursing home care records

RESUMO Objetivo: construir e validar um instrumento para monitorar a qualidade dos registros de enfermagem no Programa de Assistência Domiciliar (PAD) em um hospital universitário. Método: estudo metodológico envolvendo a elaboração de um manual e submetido à validação de conteúdo por seis juízes sob consenso ≥ 80%. A coleta ocorreu em 2012 por meio de questionário contendo: evolução de enfermagem, diagnóstico e prescrição de enfermagem e normas para os registros da equipe de enfermagem preconizadas pelo Conselho Regional de Enfermagem-SP e pela instituição. Os itens do manual foram julgados de acordo com as variáveis - relevância, pertinência, clareza e simplicidade. Resultados: das 39 proposições 100% atingiram consenso ≥ 80% em relevância, pertinência e clareza; 92,3% em simplicidade. Os itens sono/repouso, mobilidade e checagem nas atividades prescritas não atingiram consenso mínimo favorável, sendo aprimorados pelas sugestões dos juízes. Conclusão: acreditamos que o instrumento possibilitará a melhoria dos processos de trabalho no PAD. .

RESUMEN Objetivo: construir y validar un instrumento para monitorear la calidad del registros de enfermería en Programa de Atención Domiciliaria (PAD) de un Hospital Universitario. Metodo: estudio metodológico. Fue construido un manual y sometió a validación de contenido por seis jueces bajo el consenso ≥80%. La recogida currió en 2012, con un cuestionario que contiene: evolución de enfermería, diagnóstico y prescripción de enfermería y normas para los registros del personal de enfermaria estabelecidas por Consejo Regional de Enfermería-SP y por la institución. Los artículos del manual fueran juzgadso conforme las variables relevancia, pertinencia, claridad y sencillez. Resultados: de las 39 proposiciones 100% alcanzó consenso ≥ 80% en la relevancia, pertinencia y claridad; 92,3% en la simplicidad. Los itens sueño/resto, movilidad y verificar las actividades prescritas no alcanzó consenso favorable, siendo mejoradas por las sugerencias de los jueces. Conclusión: creemos que el instrumento permitirá la mejora de los procesos de trabajo en PAD. .

ABSTRACT Objective: to build and validate an instrument aimed at monitoring the quality of nursing records in the Home Care Program (HCP) of a university hospital. Method: methodological study involving the elaboration of a manual, whose content was later submitted to six experts for validation, reaching a ≥ 80% consensus. The data collection process was carried out in 2012 by means of a questionnaire comprised of the following issues: nursing evolution, nursing diagnosis, and nursing prescription, and standards for the nursing team recommended by the Regional Nursing Council of São Paulo and by the assessed institution. Manual items were judged according to the following variables: relevance, pertinence, clarity and simplicity. Results: of the 39 propositions, 100% achieved ≥ 80% agreement in the relevance, pertinence and clarity variables; 92.3% in the simplicity variable. Sleep/rest, Mobility and Check-out variables did not reach a favorable minimum consensus in the prescribed activities and were improved following suggestions from the experts. Conclusion: we believe that the instrument will enable the improvement of the HCP’s work process. .

Relationship among Shigella spp. and enteroinvasive Escherichia coli (EIEC) and their differentiation

Shigellosis produces inflammatory reactions and ulceration on the intestinal epithelium followed by bloody or mucoid diarrhea. It is caused by enteroinvasive E. coli (EIEC) as well as any species of the genus Shigella, namely, S. dysenteriae, S. flexneri, S. boydii, and S. sonnei. This current species designation of Shigella does not specify genetic similarity. Shigella spp. could be easily differentiated from E. coli, but difficulties observed for the EIEC-Shigella differentiation as both show similar biochemical traits and can cause dysentery using the same mode of invasion. Sequencing of multiple housekeeping genes indicates that Shigella has derived on several different occasions via acquisition of the transferable forms of ancestral virulence plasmids within commensal E. coli and form a Shigella-EIEC pathovar. EIEC showed lower expression of virulence genes compared to Shigella, hence EIEC produce less severe disease than Shigella spp. Conventional microbiological techniques often lead to confusing results concerning the discrimination between EIEC and Shigella spp. The lactose permease gene (lacY) is present in all E. coli strains but absent in Shigella spp., whereas β-glucuronidase gene (uidA) is present in both E. coli and Shigella spp. Thus uidA gene and lacY gene based duplex real-time PCR assay could be used for easy identification and differentiation of Shigella spp. from E. coli and in particular EIEC.

Drug resistance profiles and clonality of sporadic Shigella sonnei isolates in Ankara, Turkey

The aims of this study were to investigate drug resistance rates, types of extended spectrum beta lactamases (ESBLs), and molecular epidemiological characteristics of 43 Shigella sonnei isolates. Ampicillin-sulbactam, amoxicillin-clavulanate, chloramphenicol, and ciprofloxacin were the most active antibiotics. Five isolates harbored blaSHV-12, blaTEM-1 and blaCTX-M-15. More than 90% of the isolates had an indistinguishable pulsotype.

Patrones de susceptibilidad antimicrobiana de cepas de Shigella sonnei aisladas durante tres períodos diferentes en la Región Metropolitana, Chile / Antibiotic susceptibility patterns among Shigella sonnei, isolated during three different periods in Región Metropolitana, Chile

Background: Shigella sonnei gastroenteritis improves clinically and microbiologically with antibacterial treatment; however choosing a useful drug is a universal challenge because of in vitro susceptibility of S. sonnei frequently evolves to be resistant. Objective: To evaluate in vitro susceptibility of S. sonnei strains isolated from patients attending at the Chilean Región Metropolitana and to know the evolution that resistant patterns of S. sonnei have experienced. Material: In this study, the antimicrobial susceptibility profile of 277 isolates of Shigella sonnei was compared. The analyzed periods of time were: period I (1995-1997) 85 strains; period II (2004-2006) 92 strains and period III (2008-2009) 100 strains, in Santiago, Chile. The method performed to analyze susceptibility patterns was the disc diffusion (Kirby-Bauer). Results: The strains showed rates of resistance to ampicillin: period I, 85.8%; period II, 53.3%; period III, 100%, trimethoprim/sulfamethoxazole: period I, 50.5%; period, II 46.7%; period III, 100%, chloramphenicol: period I, 36.4%; period II, 12%; period III, 100% and tetracycline: period I, 38.8%; period II, 30.4%; period III, 100%. 98.9% of the strains showed susceptibility to quinolones. Significant differences were observed in patterns of antimicrobial resistance for both individuals and for multidrug resistance (≥ 3 antimicrobials) in the three periods (p < 0.001, χ2 test). Of all resistant strains, 17% were resistant to 1 or 2 antibiotics, while 65.7% showed a pattern of multidrug resistance; 100% of the period III strains presented multidrug resistance. Conclusion: These results showed the temporal resistance dynamics of S. sonnei circulating strains in the Chilean Región Metropolitana. Due to the endemic behavior of shigellosis in Chile, it is urgent to maintain permanent surveillance of antimicrobial resistance profiles to improve both prevention and treatment of shigellosis.

Introducción: La infección entérica producida por Shigella sonnei mejora clínicamente y microbiológicamente con antibioterapia; sin embargo, la elección del antimicrobiano es un problema universal pues la susceptibilidad in vitro de S. sonnei evoluciona frecuentemente hacia la resistencia. Objetivo: Evaluar la susceptibilidad in vitro a antimicrobianos de S. sonnei y conocer la evolución que han experimentado los patrones de resistencia de cepas aisladas de cuadros clínicos en pacientes de la Región Metropolitana, Chile. Material y Métodos: Se comparó el perfil de susceptibilidad a antimicrobianos, de 277 cepas clínicas de S. sonnei aisladas durante tres períodos: período I (1995-1997) 85 cepas; período II (2004-2006) 92 cepas y período III (2008-2009) 100 cepas, en Santiago, Chile. El perfil de susceptibilidad a antimicrobianos se determinó mediante test de difusión en agar. Resultados: Las tasas de resistencia de las cepas en los periodos I, II y III respectivamente fueron: ampicilina: 85,8%; 53,3%; 100%, cotrimoxazol: 50,5%; 46,7%; 100%, cloranfenicol: 36,4%; 12%; 100% y tetraciclina: 38,8%; 30,4%; 100%. El 98,9% de las cepas fue susceptible a quinolonas. Se observó diferencias significativas en los porcentajes de resistencia para antimicrobianos individuales y multi-resistencia (≥ 3 antimicrobianos) en los tres períodos (p < 0,001; Test de χ2). De las cepas resistentes, 17% presentó resistencia a uno ó dos antimicrobianos, 65,7% mostró multi-resistencia antimicrobiana. El 100% de las cepas del período III presentó multi-resistencia. Discusión: Estos resultados evidencian la dinámica temporal de la resistencia en cepas de S. sonnei circulantes en la Región Metropolitana. Dado que en Chile la shigelosis tiene un carácter endémico, es prioritario mantener una vigilancia constante de los perfiles de resistencia a antimicrobianos, para mejorar la prevención y el tratamiento de la shigelosis.

Colicin type 7 produced by majority of Shigella sonnei isolated from Thai patients with diarrhoea

Thirty one out of 153 strains of Shigella sonnei isolated from Thai patients with diarrhoea showed antibacterial activity against S. sonnei by agar well diffusion method. All of them harbor plasmids with the genetic determination of colicin type 7 (Js) gene but without colicin E and colicin U gene. The PCR product obtained from strain 35/44 was shown to be the gene for colicin type 7 lytic protein (cja). The partially purified bacteriocin (PPB) containing colicin type 7 of strain 35/44 was prepared and used for characterization. The antibacterial activity of PPB against a total of 17 selected Gram-positive and Gram-negative bacteria was tested. It was found that PPB of strain 35/44 was active against E. coli O157, S. sonnei and S. boydii. The sensitivity of PPB from this strain to proteinase K, trypsin and α-chymotrypsin suggests the proteinaceous nature of these antimicrobial substances. Therefore, this isolated bacterium can be regarded as bacteriocin producing bacteria. The bacteriocin produced by this isolated S. sonnei was heat stable as evidenced by its ability to maintain the activity at 80 °C for 60 min. In addition, it was stable within a wide range of pH (3-9). The molecular weight of colicin type 7 from isolated S. sonnei strain 35/44 analyzed by SDS-PAGE was 54.4 kDa composing of at least five subunits. It is to our knowledge; the first report of Thai patients with diarrhoea that S. sonnei isolated from them contained colicin type 7.

Bacteriemia por Shigellaflexneri serotipo 6 en pacientes con SIDA: Presentación de dos casos clínicos / Bacteraemia due to Shigella flexneri serotype 6 in two patients with AIDS

Infections due to Shigella usually remain localized to the digestive tract and are self-limited. Bacteremia is a potentially lethal complication that can occur in immunocompromised patients. We describe two episodes of bacteremia caused by Shigella in two adults with AIDS. In both patients, S. flexneri was recovered from stool and blood samples. The isolates belonged to serotype 6, were resistant only to trimethoprim-sulfamethoxazole and showed a similar band profile by pulsed-field gel electrophoresis. Patients received prolonged antimicrobial treatment with a favorable outcome. There were no cases of diarrhea in other individuals admitted to the emergency room. We hypothesized that patient No. 2 was infected at the hospital from patient No. 1. However, we could not establish the way of transmission. Although rare, it is important to take into account the possible occurrence of bacteremia due to Shigella or other bacterial enteropathogens in immunocompromised patients with diarrhea.

Las infecciones por Shigella spp., en general, permanecen localizadas en el tracto digestivo y tienen una evolución autolimitada. La bacteriemia es una complicación potencialmente letal que ocurre en pacientes con algún tipo de inmunocompromiso. Presentamos dos casos de bacteriemia causadas por Shigella en dos adultos con SIDA. En ambos pacientes, se recuperó Shigella flex-neri en muestras de deposiciones y sangre. Los aislados correspondieron al serotipo 6, fueron resistentes sólo a cotrimoxazol y mostraron un perfil de bandas similar por PFGE. Los pacientes recibieron tratamiento antimicrobiano prolongado y la evolución fue favorable. No se registraron otros casos de diarrea en individuos admitidos en el servicio de emergencia. La hipótesis fue que el paciente 2 adquirió la infección en el hospital a partir del paciente 1. Sin embargo, no pudimos establecer el modo de transmisión. Aunque poco frecuente, es importante tener presente la ocurrencia de bacteriemia por Shigella spp. o por otros enteropatógenos bacterianos en pacientes inmunocomprometidos con diarrea.

Shigella in Brazilian children with acute diarrhoea: prevalence, antimicrobial resistance and virulence genes

Diarrhoeal disease is still considered a major cause of morbidity and mortality among children. Among diarrhoeagenic agents, Shigella should be highlighted due to its prevalence and the severity of the associated disease. Here, we assessed Shigella prevalence, drug susceptibility and virulence factors. Faeces from 157 children with diarrhoea who sought treatment at the Children's Hospital João Paulo II, a reference children´s hospital in Belo Horizonte, state of Minas Gerais, Brazil, were cultured and drug susceptibility of the Shigella isolates was determined by the disk diffusion technique. Shigella virulence markers were identified by polymerase chain reaction. The bacterium was recovered from 10.8% of the children (88.2% Shigella sonnei). The ipaH, iuc, sen and ial genes were detected in strains isolated from all shigellosis patients; set1A was only detected in Shigella flexneri. Additionally, patients were infected by Shigella strains of different ial, sat, sen and set1A genotypes. Compared to previous studies, we observed a marked shift in the distribution of species from S. flexneri to S. sonnei and high rates of trimethoprim/sulfamethoxazole resistance.

Antimicrobial resistance in Shigella - rapid increase & widening of spectrum in Andaman Islands, India.

Background & objectives: Shigellosis is known to be a major cause of acute childhood diarrhoea in Andaman & Nicobar Islands, India. Rapid emergence of antibiotic resistance warrants continuous monitoring of sensitivity pattern of bacterial isolates. We report here the salient findings of an ongoing study on shigellosis in Andaman Islands, India, with regards to change in drug resistance pattern during the past one decade. Method: During 2006-2009, stools samples from 412 paediatric diarrhoea patients were collected and processed for isolation and identification of Shigella spp. Susceptibility to 22 antimicrobial drugs was tested and MICs were determined for 3rd generation cephalosporins, quinolones, amoxicillin-clavulanic acid combination and gentamicin. Drug susceptibility pattern of these isolates were compared with that of 33 isolates obtained during 2000-2002. Results: Shigella isolates were recovered from 50 of 412 stool samples processed. Resistance to ampicillin, nalidixic acid, tetracycline and ciprofloxacin was observed in 100, 96, 94 and 82 per cent of the isolates, respectively. The frequency of resistance to these drugs was significantly (P<0.001) higher than that observed during 2000-2002. Resistance to seven drugs was observed in 2000-2002, whereas resistance to 21 drugs was seen during 2006-2009. The number of drug resistance pattern increased from 13 in 2000-2002 to 43 in 2006-2009. Resistance to newer generation fluoroquinolones, 3rd generation cephalosporins and augmentin, which was not observed during 2000-2002, appeared during 2006-2009. Interpretation & conclusions: The frequency of resistance among Shigella isolates has increased substantially between 2000-2002 and 2006-2009 and the spectrum of resistance has widened. At present, the option for antimicrobial therapy in shigellosis in Andaman is limited to a small number of drugs. Continuous local monitoring of resistance patterns is necessary for the appropriate selection of empirical antimicrobial therapy.

The normal chain length distribution of the O antigen is required for the interaction of Shigella flexneri 2a with polarized Caco-2 cells

Shigella flexneri causes bacillary dysentery in humans. Essential to the establishment of the disease is the invasion of the colonic epithelial cells. Here we investigated the role of the lipopolysaccharide (LPS) O antigen in the ability of S. flexneri to adhere to and invade polarized Caco-2 cells. The S. flexneri 2a O antigen has two preferred chain lengths: a short O antigen (S-OAg) regulated by the WzzB protein and a very long O antigen (VL-OAg) regulated by Wzz pHS2. Mutants with defined deletions of the genes required for O-antigen assembly and polymerization were constructed and assayed for their abilities to adhere to and enter cultured epithelial cells. The results show that both VL- and S-OAg are required for invasion through the basolateral cell membrane. In contrast, the absence of O antigen does not impair adhesion. Purified LPS does not act as a competitor for the invasion of Caco-2 cells by the wild-type strain, suggesting that LPS is not directly involved in the internalization process by epithelial cells.

Quinolone-resistant Shigella flexneri Isolated in a Patient Who Travelled to India

We report a recent case in which ciprofloxacin-resistant Shigella flexneri was isolated from a 23-yr-old female patient with a history of travel to India. Prior to her admission to our internal medicine department, she experienced symptoms of high fever and generalized weakness from continuous watery diarrhea that developed midway during the trip. S. flexneri was isolated from the stool culture. Despite initial treatment with ciprofloxacin, the stool cultures continued to show S. flexneri growth. In the susceptibility test for antibiotics of the quinolone family, the isolate showed resistance to ciprofloxacin (minimum inhibitory concentration [MIC], 8 microg/mL), norfloxacin (MIC, 32 microg/mL), ofloxacin (MIC, 8 microg/mL), nalidixic acid (MIC, 256 microg/mL), and intermediate resistance to levofloxacin (MIC, 4 microg/mL). In molecular studies for quinolone resistance related genes, plasmid borne-quinolone resistance genes such as qnrA, qnrB, qnrS, aac(6')-Ib-cr, qepA, and oqxAB were not detected. Two mutations were observed in gyrA (248C-->T, 259G-->A) and 1 mutation in parC (239G-->T). The molecular characteristics of the isolated S. flexneri showed that the isolate was more similar to the strains isolated from the dysentery outbreak in India than those isolated from Korea.

Surveillance of antibiotic susceptibility pattern among shigella flexneri strain isolated in Nagpur district during three years period, January 2009-January 2012.

Objective : In the few cases of childhood dirrhea that require the antimicrobial therapy, the correct choice of the drug depends on detailed previous knowledge of local strains and pattern of antimicrobial resistance. Shigellosis is one of the most improtant examples of this group of intestinal infections. In order to establish such parameters in Nagpur city, this study was carried out to determine the antimcrobial resistance profile of Shigella flexneri isolated from patients suffering from diahhrea admitted to Various hoapitals in Nagpur district, India. Materials and Methods: The study included 110 stool samples collected from patients during the 3 year period. All the isolates were characterized and confirmed by VITEK® 2 GN ID cards and antimicrobial susceptibility was tested by VITEK® 2 AST test cards. Results: We received 73 positive cultures of S. flexneri out of 110 stool samples during three year periods of January 2009 to January 2012. S. flexneri strains presented a high resistance rate to Ampicillin (100%), Chloramphenicol (76.71%), Trimethoprime-sulfamethaxazole (TMP-SMZ) (68.49%) and low resistance to third- and fourth-generation Cephalosporin. None of the isolates was found to be resistant to Ciprofloxacin (MIC ≥ 4), Norfloxacin (MIC ≥12), and Nalidixic acid (MIC ≥30). Conclusion: Our results provide data on antimicrobial resistance to choose a proper antibiotic for the treatment of Shigellosis in our country. According to current findings, Quinolones and Cephalosporins are the drug of choice for the diarrheic patients. In conclusion, systematic monitoring is needed to identify changes in the antimicrobial resistance.

Frequency and antimicrobial susceptibility of Shigella species isolated in Children Medical Center Hospital, Tehran, Iran, 2001-2006

Appropriate antimicrobial treatment of shigellosis depends on identifying its changing resistance pattern over time. We evaluated 15,255 stool culture submitted from July 2001 to June 2006 to the Laboratory of Children Medical Center Hospital. Specimen culture, bacterial identification, and disk diffusion susceptibility testing were performed according to National Committee for Clinical Laboratory Standards guidelines. From 15,255 stool samples, 682 (4.5 percent) were positive for Shigella species. The most common species of Shigella were S. flexneri (48 percent) and S. sonnei (45 percent); other results were S. dysenteriae (5 percent) and S. boydii (2 percent). The rate of Sensitivity to ceftriaxone (95 percent), ceftizoxime (94 percent), and nalidixic acid (84 percent) were among our isolates. Resistance to co-trimoxazole and ampicillin was 87 percent and 86 percent, respectively. S. flexneri was more multiresistant than other species (47.9 percent). Our isolates are overall most sensitive to ceftriaxone, ceftazidime, and nalidixic acid (> 84 percent). They were most resistant to co-trimoxazole and ampicillin (> 86 percent). Because resistance varies according to specific location, continuous local monitoring of resistance patterns is necessary for the appropriate selection of empirical antimicrobial therapy.

Fatality due to shigellosis with special reference to molecular analysis vi Shigella sonnet strains isolated from the fatal cases

Shigellosis as a global human health problem is more severe than other forms of gastroenteritis and causes over a million deaths in developing countries worldwide annually. Fatality due to shigellosis is usually due to dehydration and two-third of fatalities are seen among children. The aim of current study was to describe fatal cases of shigellosis due to infection with Shigella sonnei and S.flexneri. We investigated the fatal cases of shigellosis among all children with acute diarrhea admitted to Children's Medical Center, Tehran, Iran. Bacterial isolation and identification was achieved according to standard bacteriological methods. Antibiotic susceptibility tests, plasmid profiling and ribotyping were performed to investigate the clonal relationship among the isolates. Among 1200 children with acute diarrhea, 140 [12.7%] cases had shigellosis. Of these, three patients died. No signs of severe dehydration were observed among the fatal cases. The symptoms were not improved following antibiotic therapy and all three cases died after 24 h of hospitalization despite receiving intensive treatments. Stool cultures yielded S.flexneri and S. sonnei for one and two cases, respectively. The isolates were resistant to streptomycin, ampicillin, and sulfamethoxazole-trimethoprim. 5. sonnei strains were further studied and showed a single pattern of antibiotic susceptibility and ribotyping. Mortality due to species other than 5. dysenteriae is rare, however, in current study we found S. sonnei and S.flexneri as the cause of fatality among pediatric patients during the study