Usefulness of the outer membrane proteins of Shigella sonnei in developing an antibody-based immunoassay for the diagnosis of shigellosis

@#Conventional culture method and biochemical tests remain as the ‘gold standard’ method for the identification of S. sonnei which are time-consuming. We have discovered previously the potential of three OMPs of S. sonnei (33.3 kDa, 43.8 kDa and 100.3 kDa) as biomarkers in the diagnostic test for shigellosis. Here, we evaluated the performance of the outer membrane proteins of S. sonnei for the development of an antibody-based immunoassay for the detection of S. sonnei infections. All threetarget proteins were specifically recognized when probed with S. sonnei sera. In addition, another two potential proteins of molecular weight 29.0 kDa and 88.2 kDa in size were also exclusively recognized by the IgA when probed with S. sonnei sera. The optimized ELISA demonstrated higher sensitivity and specificity which exceeded 86.0%. In conclusion, the identified target proteins showed great potential as diagnostic biomarkers for the detection of S. sonnei infections in patients.

A case study of symptomatic urinary tract infection by Shigella sonnei in adult female and a short review on drug-resistant Shigella species

Shigella species belong to family Enterobacteriaceae and are causative agents of bacillary dysentery. The whole spectrum of disease caused by Shigella species is called Shigellosis. Shigella has four major subgroups: Shigella dysenteriae, Shigella flexneri, Shigella boydii, and Shigella sonnei. S. sonnei causes the mildest form of bacillary dysentery, and in many cases, it causes only mild diarrhea. It is the most common Shigellosis in developed countries. There are few reported cases of asymptomatic bacteriuria due to S. sonnei both in adults and pediatric patients. Few cases of symptomatic urinary tract infection (UTI) are also reported. In pediatric patients, the common risk factor for UTI is found to be vesicoureteric reflux, especially in females. Recent studies done in various countries show an alarming increase in resistance of Shigella species to commonly used antibiotics such as chloramphenicol, ampicillin, co-trimoxazole, nalidixic acid, fluoroquinolones, macrolides, and cephalosporins. Many outbreaks of Shigellosis by multidrug-resistant (MDR) strains have also been reported. Shigella rarely causes extraintestinal manifestations such as hemolytic uremic syndrome, hyponatremia, reactive arthritis, altered neurologic state, bacteremia, UTI, and vulvovaginitis. UTI is a rare complication of Shigella infection. Here, we report a case of UTI due to S. sonnei in an adult female with diabetes mellitus (DM). We have also done a short review of increasing antibiotic resistance among Shigella species. The Institutional Ethics Committee approval was obtained to publish this case study. A 64-year female presented to an outpatient clinic with symptoms of UTI. Urine culture was done by the semi-quantitative method in blood agar plate and MacConkey agar. A Gram-negative bacilli were isolated with a significant colony count of >100,000 cfu/ml. Antibiotic sensitivity was done by both disc diffusion method and minimum inhibitory concentration. Stool culture was also done after 4 days. In this case study, S. sonnei was isolated from urine, but stool culture done after 4 days of treatment with antibiotic was negative. The patient was newly diagnosed with type 2 DM. Hence, DM could be a risk factor for S. sonnei UTI in the elderly. Taking into consideration the emergence of antibiotic resistance among S. sonnei isolates, knowledge of antibiotic sensitivity pattern is crucial in the treatment of such infections. In our study, the isolate was not MDR. It was sensitive to ampicillin, cefixime, cefotaxime, ciprofloxacin, nitrofurantoin, and norfloxacin and azithromycin and resistant to co-trimoxazole and nalidixic acid.

Epidemiological and pathogenic features of a bacillary dysentery outbreak in a boarding school caused by Shigella sonneri / 中华流行病学杂志

Objective@#To investigate the etiologic and epidemiologic features of an infectious diarrhea outbreak in a boarding school in Fuyang city, Anhui province.@*Methods@#Traceability hypothesis of this study was tested according to the epidemiological characteristics of the cases. Feces, anal swabs, water samples and food residues related to the patients and chefs were collected for pathogen isolation and detection. Biochemical identification, virulence gene detection, drug susceptibility test, PFGE and multilocus sequence typing were performed.@*Results@#The incidence rate (3.41%) of different dormitory buildings within the water supply area by shallow wells was higher than that (0.98%) of the deep wells, with statistical significance (χ2=17.215, P<0.001). Sixteen strains belonged to the Shigella Sonneri family were isolated from the patient’s samples, and all carrying the ipaH gene. Seven strains belonged to sen and ial genes. Set1 gene that did not appear in all the 16 strains were highly resistant to ampicillin, tetracycline, compound xinnomine, cefazoline, cefotaxime, gentamicin, naphthidinic acid and streptomycin, including 9 strains to doxycycline. The pulse field pattern of the 16 strains of Shigella sonneri appeared the same, with the ST type as ST152.@*Conclusion@#When combined data from the etiological and epidemiological investigation, it was confirmed that Shigella sonneri was the pathogen of this outbreak, and water from the shallow wells might be responsible for the source of infection.

Caracterización proteómica de vesículas de membrana externa extraídas de Shigella sonnei / Proteomic characterisation of outer membrane vesicle extracted from Shigella sonnei

Las vacunas compuestas por vesículas de membrana externa (VMEs) previenen de manera exitosa la enfermedad meningocócica del serogrupo B. Esta plataforma tecnológica de obtención puede ser aplicada para otros patógenos bacterianos Gram negativos. Una vacuna de VMEs desarrollada contra Shigella sonnei fue obtenida a través de una extracción de componentes celulares y su caracterización por electroforesis en geles de poliacrilamida unidimensional (1D). Se estudiaron las mejores condiciones de solubilización de las muestras, separación electroforética e identificación a través de espectrometría de masas acoplada a cromatografía de alta presión después del corte de las bandas y su tratamiento enzimático con tripsina. En esta etapa se identificaron un total de 57 proteínas en 23 bandas (2,5 proteínas por banda escindida), 47 de las proteínas no repetidas. Las proteínas inmunogénicas presentes en VMEs de S. sonnei fueron cuantificadas en cuanto a masa molecular por 1D-Western blotting en membranas de nitrocelulosa con anticuerpos obtenidos a partir de ratones inmunizados con las VMEs. Como que las bandas electroforéticas 1D contenían más de una proteína, se estudiaron las mejores condiciones de separación por el método de electroforesis bidimensional (2D) para el establecimiento del mapa proteico; tal que el incremento del tamaño de las tiras, el tiempo de focalización y la aplicación catódica garantizaron la mayor resolución(AU)

Outer membrane vesicles (OMVs) vaccines successfully prevent Group B meningococcal disease. This platform technology may be applied against other Gram negative bacterial pathogens. An OMV vaccine against Shigella sonnei was prepared by detergent extraction of cells and characterised by one-dimensional polyacrylamide gel electrophoresis (1D). The protein components were quantified by staining and scanning and the composition of bands were defined by coupled high-performance low chromatography/electrospray ionization tandem mass spectrometry after band excision and in-gel trypsin digestion. 57 proteins contained in 23 bands (2.5 proteins/split band) were detected, 47 of them were not repeated. The S. sonnei OMVs immunogenic proteins were identified by 1D-immunoblotting, after transfer of proteins to a nitrocellulose membrane and treatment with antibodies generated by immunisation of mice with the OMVs. The bands detected by 1D had more than a single proteins, that is why we studied the best conditions for molecular separation by two-dimension electrophoresis (2D) for establishing the protein map; such that the increase of strips size, time of isoelectric focusing (IEF) and cup-cathodic loading guaranteed the highest resolution(AU)

Etiologic characteristics of Shigella sonnei strains isolated from some areas of Guangdong province and Guangxi Zhuang Autonomous Region of China, 2014-2016 / 中华流行病学杂志

Objective To investigated the etiologic characteristics of Shigella (S.) sonnei strains causing outbreaks and sporadic cases in some areas of Guangdong province and Guangxi Zhuang Autonomous Region during 2014-2016. Methods Fourteen S. sonnei strains isolated from outbreaks and 6 S. sonnei strains from sporadic cases from Guangdong and Liuzhou of Guangxi Zhuang Autonomous Region were tested for antimicrobial resistance and analyzed by pulsed-field gel electrophoresis (PFGE). Six typical strains were selected for whole genome sequencing typing and compared with 51 strains isolated both at home and abroad from NCBI genome database. Results The antibiotic resistance test indicated the isolates had high resistance rate to ampicillin, tetracycline, gentamicin, trimethoprim/sulfamethoxazole and nalidixic acid, while sensitive to azithromycin, chloromycetin and imipenem. PFGE showed high similarity (93.2%) among the strains isolated from different areas. The whole genome sequencing analysis also revealed that all the typical strains wereclustered into a same evolution branch, close to some strains from Korea. Conclusions The S. sonnei strains isolated from some areas of Guangdong and Guangxi Zhuang Autonomous Region showed high resistance to commonly used antibiotics, but they were sensitive to azithromycin, chloramphenicol and imipenem. The isolates in this study also showed similar PFGE patterns and close phylogenic evolution.

Etiologic characteristics of Shigella sonnei strains isolated from some areas of Guangdong province and Guangxi Zhuang Autonomous Region of China, 2014-2016 / 中华流行病学杂志

Objective To investigated the etiologic characteristics of Shigella (S.) sonnei strains causing outbreaks and sporadic cases in some areas of Guangdong province and Guangxi Zhuang Autonomous Region during 2014-2016. Methods Fourteen S. sonnei strains isolated from outbreaks and 6 S. sonnei strains from sporadic cases from Guangdong and Liuzhou of Guangxi Zhuang Autonomous Region were tested for antimicrobial resistance and analyzed by pulsed-field gel electrophoresis (PFGE). Six typical strains were selected for whole genome sequencing typing and compared with 51 strains isolated both at home and abroad from NCBI genome database. Results The antibiotic resistance test indicated the isolates had high resistance rate to ampicillin, tetracycline, gentamicin, trimethoprim/sulfamethoxazole and nalidixic acid, while sensitive to azithromycin, chloromycetin and imipenem. PFGE showed high similarity (93.2%) among the strains isolated from different areas. The whole genome sequencing analysis also revealed that all the typical strains wereclustered into a same evolution branch, close to some strains from Korea. Conclusions The S. sonnei strains isolated from some areas of Guangdong and Guangxi Zhuang Autonomous Region showed high resistance to commonly used antibiotics, but they were sensitive to azithromycin, chloramphenicol and imipenem. The isolates in this study also showed similar PFGE patterns and close phylogenic evolution.

Resistance mechanisms of blaCTX-M-55 in a clinical Shigella sonnei strain / 军事医学

Objective To characterize the resistance mechanisms of a clinical Shigella sonnei strain harboring blaCTX-M-55 .Methods A double-disk synergy test was conducted to detect ESBL.Antibiotic resistance genes were determined by PCR followed by amplicon sequencing.Conjugation experiments were performed to verify the transferability of the plasmids carrying ESBL genes.The minimum inhibitory concentration values were tested using VITEK 2.The transposition unit was confirmed by DNA sequencer,and the transcriptional start site was identified using primer extension assay.Results Strain #1083 produced CTX-M-55,which was encoded by plasmid p1083-CTXM that could be transferred into E.coli through conjugation experiments to confer corresponding antibiotic resistance to the transconjugant #1083-EC600.The transposition unit mediating the transfer of blaCTX-M-55 was ISEcp1-blaCTX-M-55 -Δorf477.ISEcp1 offered strong promoter regions for the resistance genes,facilitating their expressions.Besides,the expressions were constant,not induced by antibiotics.Conclusion BlaCTX-M-55 on plasmids is the major resistance genes for strain #1083.Their expressions and spread are mediated by the insertion sequence ISEcp1.

Surveillance on the etiology and molecular epidemiology of Shigella sonnei isolated in Henan province from 2011 to 2014 / 中华流行病学杂志

Objective To detect and analyze the distribution of virulence factors,antimicrobial resistance and pulsed field gel electrophoresis (PFGE) patterns of Shigella sonnei,isolated in Henan province from 2011 to 2014.Methods Samples of diarrhea patients were collected and isolated with SS selective culture medium in 37 ℃ for 18-24 hours.All strains were identified under the Kligler iron agar/motility-indol-urea biochemical action and API20E biochemical system.Serological typing and prepared DNA template were carried out with thermal cracking method and multiplex PCR,to detect the virulence genes of Shigella sonnei.According to the molecular typing method and K-B drug susceptibility testing method published by the international PulseNet bacterial infectious disease monitoring network and USA clinical and Laboratory Standards Institute,antimicrobial susceptibility tests and PFGE molecular characteristics of these positive strains isolated from sentinel hospitals patients stool samples were analyzed.Results Among the 98 strains of Sonnei type Ⅰ and 118 strains of Sonnei type Ⅱ,all the strains carried carry different virulence genes including SHET-1B,SHET-2,ial,ipaH genes,with 4 kinds of virulence gene combination types.All the 216 strains of Shigella sonnei belonged to the multi-drug resistant strains,including 34 isolates resistant to 2-4 kinds of antibiotics (15.7％),147 isolates to 5-8 kinds of antibiotics (68.1％),24 to 9-10 kinds of antibiotics (11.1％),7 to 11 kinds of antibiotics (3.2％),and 4 to 13 kinds of antibiotics (1.9％).A total of 100 strains of Shigella sonnci were divided into 31 molecular patterns,digested by Xba Ⅰ and PFGE.Each pattern contained 1-13 strains with similarities ranged from 68.6％-100.0％.Conclusions All the Shigella sonnei strains carried virulence pathogenic factors,presenting serious status on drug resistance.PFGE fingerprinting patterns showed high polymorphism and dominant characteristics.PFGE patterns of partial strains and corresponding antidrug spectrum presented certain relevance and with same aggregation relationship.

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.

Brote de shigelosis en la ciudad de Luján, Argentina / Shigelosis outbreak in the city of Lujan, Argentina

El objetivo del estudio fue describir un brote por Shigella sonnei ocurrido en julio de 2012 en Luján, Buenos Aires, Argentina. Estuvieron afectadas 5 personas que asistieron a una reunión familiar, donde consumieron una rosca vienesa de elaboración artesanal adquirida en un comercio. Todos presentaron fiebre, dolores articulares, escalofríos y diarrea no sanguinolenta con mucus. Se realizaron coprocultivos en los afectados y análisis microbiológicos de los ingredientes. Se aisló y caracterizó S.sonnei de todos los pacientes y de la crema de almendras empleada en la preparación de la rosca vienesa. A los aislamientos se les determinó el perfil de sensibilidad a los antimicrobianos y el genético por electroforesis en campo pulsado. Los resultados demostraron la relación genética de los aislamientos, y esto confirmó la ocurrencia de los casos por exposición a una misma fuente de infección, la crema de almendras. Al ser un ingrediente industrial, de improbable contaminación inicial, la crema de almendras podría haber sufrido una contaminación durante la manipulación en la panadería

The aim of this study was to describe an outbreak of Shigella sonnei that occurred in the city of Lujan, Buenos Aires, Argentina, in July 2012. Five individuals were affected after eating a handmade Viennese-style pastry at a family gathering. All of them presented with fever, joint pain, chills and non-bloody diarrhea containing mucus. Stool cultures were performed in all cases and the samples taken from the pastry ingredients were analyzed microbiologically. S.sonnei was isolated and identified in all the patients involved as well as in the almond cream filling. The isolates were analyzed for determining the antimicrobial susceptibility and genetic profiles by pulsed field gel electrophoresis (PFGE). The results showed the genetic relationship among the isolates, confirming that the cases occurred due to the patients' exposure to the same source of infection, i.e., the almond cream. Being the almond cream an industrially-manufactured ingredient, an initial contamination could have been unlikely; however contamination might have occurred as a result of manipulation in the bakery

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.

Antimicrobial resistance and virulence genes of Shigella sonnei in Chang-sha area / 中国感染控制杂志

Objective To investigate the antimicrobial susceptibility and the carrying of virulence genes of Shigel-la sonnei (S.sonnei)in Changsha area.Methods Susceptibilities of 30 S.sonnei strains to 6 kinds of antimicrobial agents (ampicillin,cefotaxime,nalidixic acid,ciprofloxacin,gentamicin,compound sulfamethoxazole)were detec-ted by disc diffusion method;4 virulence genes (set1 ,sen,ial,ipaH)were amplified by polymerase chain reaction (PCR).Results Of all detected antimicrobial agents,ampicillin,nalidixic acid and compound sulfamethoxazole had the highest resistance rate(100%);while ciprofloxacin and gentamicin had higher susceptibility rate (93.33% and 83.33% respectively).PCR revealed that the carrying rate of set1,sen,ial and ipaH in 30 S.sonnei strains was 0, 13.33%,13.33% and 53.33% respectively.Conclusion Resistance of S.sonnei to the third-generation cefalosporins and sulfonamides are quite serious,third-generation quinolones can still be used as the first choice of drug treatment for S.sonnei infection.Carrying rate of virulence genes are low among S.sonnei in Changsha area.

Detection of drug resistance genes in integron of Shigella sonnei from six cities of Jiangsu Province in 2011 / 中华传染病杂志

Objective To investigate the resistance status of different integrons of Shigella sonnei (S.sonnei) and to analyze the distribution of resistant genes in integrons in Jiangsu Province.Methods A total of 32 strains of S.sonnei isolated from six cities of Jiangsu Province in 2011 were collected.The antibiotic susceptibility was tested by disk diffusion method.The molecular homology was analyzed by pulsed field gel electrophoresis (PFGE).The detection and classification of integrons were achieved by analyzing the positive polymerase chain reaction (PCR) products using restriction fragment length polymorphism (RFLP).RFLP and DNA sequencing were used to analyze the resistance genes in integrons.Results Multi-drug resistance (MDR) was detected in 28 (87.5％) S.sonnei strains.The resistant rates to ampicillin,nalidixic acid and tetracycline were highest (87.5％,respectively).However,it was sensitive to norfloxacin.PFGE analysis showed that there were 3 kinds of homologous clones involving 31 strains of the 32 S.sonnei strains.Among them,2,5 and 24 strains had the same clones,respectively.Accordingly,they spread within one,two and five different cities.The detection rates of class 1,class 2 and the atypical class 1 integrons in S.sonnei were 62.5％ (20/32),81.3％ (26/32) and 21.9％ (7/32),respectively,and no class 3 integron was detected.Sequence analysis of class 1 integron variable area revealed that it contained multiple resistant genes (aacA4-cmlA1 and dfrA1-aadA 1) ; dfrA1-sat 1-aadA 1 from class 2 integron and blara-30-aadA 1 from atypical class 1 integron were also identified.Conclusions In 2011,homologous S.sonnei strains spread among different cities in Jiangsu Province.MDR strains are prevalent and integrons are widespread which mediated the emergence of MDR strains.

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.

Antagonistic activity expressed by Shigella sonnei: identification of a putative new bacteriocin

Bacteriocins are antibacterial, proteinaceous substances that mediate microbial dynamics. Bacteriocin production is a highly disseminated property among all major lineages of bacteria, including Shigella. In this paper, we addressed the purification and characterisation of a bacteriocin produced by a Shigella sonnei strain (SS9) isolated from a child with acute diarrhoea. The substance was purified through ammonium-sulphate precipitation and sequential steps of chromatography. The intracellular fraction obtained at 75% ammonium sulphate maintained activity following exposure to pH values from 1-11 and storage at -80ºC for more than two years and was inactivated by high temperatures and proteases. The molecular mass of the purified bacteriocin was determined by mass spectrometry to be 18.56 kDa. The N-terminal sequence of the bacteriocin did not match any other antibacterial proteins described. A putative new bacteriocin produced by S. sonnei has been detected. This bacteriocin may represent a newly described protein or a previously described protein with a newly detected function. Considering that SS9 expresses antagonism against other diarrhoeagenic bacteria, the bacteriocin may contribute to S. sonnei virulence and is potentially applicable to either preventing or controlling diarrhoeal disease.

CTX-M-55-Type Extended-Spectrum beta-lactamase-Producing Shigella sonnei Isolated from a Korean Patient Who Had Travelled to China

We report a case of CTX-M-55-type extended-spectrum beta-lactamase (ESBL)-producing Shigella sonnei infection in a 27-year-old Korean woman who had traveled to China. The patient was admitted to the hospital due to abdominal pain, watery diarrhea, and fever (39.3degrees C). S. sonnei was isolated from her stool specimens, and the pathogen was found to be resistant to cefotaxime due to CTX-M-55-type ESBL. Insertion sequence (IS)Ecp1 was found upstream of the blaCTX-M-55 gene. The blaCTX-M-55 gene was transferred from the S. sonnei isolate to an Escherichia coli J53 recipient by conjugation. Pulsed-field gel electrophoresis and Southern blotting revealed that the blaCTX-M-55 gene was located on a plasmid of approximately 130 kb.

Diarreia associada a Shigella em crianças e sensibilidade a antimicrobianos / Diarrhea associated with Shigella in children and susceptibility to antimicrobials

OBJETIVO: Avaliar a distribuição e suscetibilidade a antimicrobianos de Shigella isolada de crianças com diarreia aguda e sem diarreia em Teresina (PI). MÉTODOS: Quatrocentas crianças com idade até 60 meses foram estudadas. Fezes foram coletadas de todos os pacientes entre janeiro de 2004 e agosto de 2007. Shigella foi identificada por métodos convencionais e antibiograma e pesquisa de β-lactamase de espectro ampliado (ESBL) foram realizados por difusão em ágar. RESULTADOS: Shigelose foi detectada apenas em crianças com diarreia aguda (26/250; 10,4%), especialmente naquelas entre 6 e 24 meses de idade e nos meses chuvosos. Shigella foi suscetível a ceftriaxona, ciprofloxacina e ácido nalidíxico. Mais da metade das amostras foram resistentes a sulfametoxazol-trimetoprim e ampicilina. ESBL não foi detectada. CONCLUSÕES: S. flexneri é comum em Teresina. A resistência a ampicilina e sulfametoxazol-trimetoprim é preocupante, pois estas drogas são amplamente utilizadas na prática e sulfametoxazol-trimetoprim ainda é recomendada para tratamento de crianças com suspeita de shigelose.

OBJECTIVE: To evaluate the distribution and susceptibility to antimicrobials of Shigella isolated from children with acute diarrhea and without diarrhea in Teresina, state of Piauí, Brazil. METHODS: Four hundred children aged up to 60 months were studied. Stools were collected from all the patients between January 2004 and August 2007. Shigella was identified by conventional methods and antibiogram and extended-spectrum β-lactamase (ESBL) were performed by agar diffusion. RESULTS: Shigellosis was only detected in children with acute diarrhea (26/250; 10.4%), especially in those aged from 6 to 24 months and in the rainy months. Shigella was susceptible to ceftriaxone, ciprofloxacin and nalidixic acid. More than half of the strains were resistant to sulphametoxazole-trimethoprim and ampicillin. ESBL was not detected. CONCLUSIONS: S. flexneri is common in Teresina. The resistance to ampicillin and sulphametoxazole-trimethoprim gives cause for concern, as these drugs are widely used in practice and sulphametoxazole-trimethoprim is also recommended for treating children suspected of having shigellosis.

Study on the resistance-related genes of Shigella sonnei with decreased susceptibility to fluoroquinolones / 中华传染病杂志

Objective To investigate the resistance-related genes of Shigella sonnei with decreased susceptibility to fluoroquinolones.MethodsA total of 131 strains of Shigella sonnei were analyzed for their antimicrobial susceptibility.Mutations within the quinolone resistance determining regions (QRDR) of gyrA and parC were detected by polymerase chain reaction (PCR) and PCR products were then sequenced. Meanwhile, the plasmid-mediated quinolone resistance (PMQR) genes,qnr and aac(6')-Ib-cr were screened by PCR.ResultsResistance rates of 131 Shigella sonnei isolates to nalidixic acid,tetracycline,ampicillin and trimethoprim-sulfamethoxazole were 100.0％,93.9％,93.2％ and 92.8％,respectively.All strains were susceptible to norfloxacin,ciprofloxacin,levofloxacin,while 94％ nalidixic acid-resistant Shigella sonnei strains showed reduced susceptibilities to fluoroquinolones.All of nalidixic acid-resistant Shigella sonnei strains presented a single mutation at codon 83 (Ser→Leu) of gyrA genes,but no mutations were detected in parC gene.And PMQR genes qnr and aac (6’)-Ib-cr were not detected.Conclusions The nalidixic acid-resistant Shigella sonnei strains with reduced susceptibility to fluoroquinolones are common in the clinical practice,which may mainly due to a single mutation at codon 83 (Ser→Leu) of gyrA genes.

Pesquisa de bacteriófagos em água suspeita de contaminação por vírus da hepatite A / Study of bacteriophages in water suspected of contamination by hepatitis A virus

Os vírus entéricos, quando presentes no trato gastrointestinal de indivíduos infectados, são eliminados pelas fezes em grandes quantidades podendo contaminar, direta ou indiretamente, as águas destinadas ao consumo humano. O ser humano é o único hospedeiro natural do vírus da hepatite A. A detecção de colifago e de fago de Shigella sonnei em água pode ser indicativa da presença destes vírus. No presente estudo foi realizado o diagnóstico laboratorial presuntivo de um surto de hepatite A, pela pesquisa de bacteriófagos, em uma amostra de água de poço e o estudo da sobrevivência dos fagos de S. sonnei em água. A análise revelou resultado positivo para fagos de Shigella e negativo para colifagos. Quanto aos ensaios de sobrevivência, a presença dos fagos de S. sonnei foi detectada na água do poço naturalmente contaminada até o nono dia de conservação em temperatura ambiente.

The enteric viruses are present in the gastrointestinal tract of infected individuals, being eliminated in feces in large quantities and can directly or indirectly contaminate water intended for human consumption. Humans are the only natural hosts for hepatitis A. Detection of coliphages and phage of Shigella sonnei in water may indicate the presence of these viruses. In the present study was done the presumptive laboratory diagnosis of an outbreak of hepatitis A through search of bacteriophages in a sample of well water and the study of survival of shigelafagos in water. The analysis revealed positive for phages of S. sonnei and negative for coliphages. For the tests of survival, the presence of phages of S. sonnei was detected in naturally contaminated well water until the ninth day of storage at room temperature.

A School Outbreak of Shigella sonnei Infection in China: Clinical Features, Antibiotic Susceptibility and Molecular Epidemiology.

Objective: To describe the clinical features of infection, and the antibiotic susceptibility of epidemic strains, and investigate plasmid maps and integrons of the isolates from an outbreak of Shigella sonnei infection at an elementary school in southwest China. Study design: Cross-sectional study. Setting: An elementary school and five hospitals in Chengdu in southwest China. Results: There were 1,134 students in the school. 937 (82.6%) students had signs and symptoms. Of the 568 (60.6%, 568/937) hospitalized students, 93.3% 86.8%, 72.4%, and 28.9% of the hospitalized patients had diarrhea, fever, abdominal pain, and vomiting, respectively. S. sonnei strains were isolated from the stool samples of 36.0% (337/937) students. All of the outbreak isolates had the same high-level antimicrobial resistance and plasmid profiles, which were different from that of sporadic strains. All the outbreak S. sonnei isolates were positive for the integrin gene and contained class 2 integron; however, two outbreak isolates contained class 1 and class 2 integrons. Conclusions: Diarrhea, fever, and abdominal pain were the three most common clinical manifestations observed in patients infected with S. sonnei. High-level antibiotic resistance was observed among Shigella species.