Reverse vaccinology approach for the identification and characterization of outer membrane proteins of Shigella flexneri as potential cellular- and antibody-dependent vaccine candidates

Dysentery by CTX-M Type ESBL Producing Shigella flexneri / Disentería por Shigella flexneri productora de BLEE tipo CTX-M

According to the World Health Organization, diarrheal infections cause 525 000 deaths of children under five years of age every year, and shigellosis. Shigellosis is a relevant cause of dysentery, which increases the morbidity and mortality in pediatric patients. Therefore, emergingthe emergence of antimicrobial resistant strains of Shigella is a concerningworrisome problem worldwide. We report the case of a 7-year-old patient with acute dysentery caused by CTX-M Type ESBL Producing Shigella flexneri, being. This was the first case treated in the Specialties Hospital of Specialties of the Armed Forces N°1, in Quito, Ecuador. The antibiogram demonstrated sensibilityshowed sensitivity to ampicillin-sulbactam. As a result, after five days of microbiologically directed treatment, the patient improved his condition without relapse. Proper clinical diagnoses and accurate laboratory studies like stool culture and antibiogram are crucial to givingindicate an appropriate therapy in infections caused by Shigella and other enteric bacilli(AU)

Según la Organización Mundial de la Salud, las infecciones diarreicas provocan 525 000 muertes de niños menores de cinco años de edad cada año. La shigelosis es una causa importante de disentería que aumenta la morbilidad y mortalidad de los pacientes pediátricos. Es por eso que el surgimiento de cepas de Shigella resistentes a los antibióticos es un preocupante problema a nivel mundial. Presentamos el caso de un paciente de 7 años de edad con disentería aguda provocada por Shigella flexneri productora de BLEE tipo CTX-M. Se trata del primer caso tratado en el Hospital de Especialidades de las Fuerzas Armadas Nº 1, en Quito, Ecuador. El antibiograma mostró sensibilidad a la combinación ampicilina/sulbactam. Al cabo de cinco días de tratamiento microbiológico, el paciente mejoró su estado y no se produjeron recaídas. Un diagnóstico clínico correcto, así como estudios precisos de laboratorio como los cultivos de heces y los antibiogramas, son vitales para indicar una terapia apropiada en las infecciones causadas por Shigella y otros bacilos entéricos(AU)

In Vitro Susceptibility Of Isolated Shigella Flexneri And Shigella Dysenteriae To The Ethanolic Extracts Of Trachyspermum Ammi And Peganum Harmala

Objective: This study represents the first attempt to investigate the antimicrobial activity of Peganum harmala, and Trachyspermum ammi seeds extract against the isolated bacillary dysentery-causing microorganisms. Methods: T. ammi and P. harmala were extracted by 96% ethanol using Soxhlet apparatus. The extracts were screened for their phytochemical constituents. Their antimicrobial activity against the isolated dysentery-causing microorganisms was evaluated using the agar diffusion method. Results: The antimicrobial activity result showed that, the two isolated bacteria, Shigella flexneri, and Shigella dysenteriae were found to be sensitive to the extract of T. ammi seed with inhibition zones up to 25 mm, compared to the inhibition zone of 20 mm produced by Gentamycin standard drug, this is mainly due to the presence of the different phytochemical in the extract such as tannin, flavonoids, terpenoids which are well known for their antimicrobial effects. The two isolated bacteria were found to be insensitive (zero mm) to P. harmala extract, Amoxicillin, and Amoclan (Amoxicillin+clavulanic acid) standard drugs, this is due to the fact that, the phytochemicals constituents of P. harmala possess the antagonistic effect to each other’s. Addition to; these bacteria became resistant to both Amoxicillin and Amoclan. Conclusion: From the results it concludes, T. ammi seeds extract had a considerable level of antimicrobial activity against bacillary dysentery-causing microorganisms resistant to Amoxicillin and Amoxicillin+clavulanic acid drugs.

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.

Study on the mechanism of serotype conversion of historical isolates of Shigella flexneri / 中华预防医学杂志

Objective@#The serotype screening of Shigella flexneri from 1934 to 1965 preserved by the National Center for Medical Culture Collections was carried out, and the molecular characteristics of the serotype conversion strains were studied.@*Methods@#Serotyping of Shigella flexneri in this study was conducted by slide agglutination and multiplex PCR, respectively. The gtrⅡ gene sequence alignment and pulsed field gel electrophoresis typing were performed on the serotype conversion strains.@*Results@#Among the 255 strains of Shigella flexneri preserved in CMCC (B) from 1934 to 1965, 79 were carrying gtrⅡ gene, of which 19 strains and 1 strain were agglutinated with the Y serotype and X serotype, respectively, and furthermore, the multiplex PCR assays results showed serotypes 2a and 2b, respectively, and the strains were considered to have serotype conversion. The 20 strains carrying the gtrⅡ gene showed multiple nucleotide mutations. Besides 3 strains of 3 amino acid mutations, the amino acid sequences of the other 17 strains showed a stop codon in advance, resulting in functional inactivation of gtrⅡ. PFGE analysis revealed that the similarity between the serotype Y strain carrying the gtrⅡ gene and the serotype 2a strain was 75.8%-100%, and the similarity between the serotype X strain carrying the gtrⅡ gene and the serotype 2b strain was 81.6%-100%.@*Conclusion@#Mutations in the gtrⅡ gene are more complicated in serotype-transforming Shigella flexneri serotype Y or X strains. Molecular typing suggests that the serotype-transforming Shigella flexneri serotype Y or X strains may be derived from the Shigella flexneri serotype 2a or 2b, and advance the serotype conversion to 1949.

Characterization of Extended-Spectrum β-Lactamase Genes of Shigella flexneri Isolates With Fosfomycin Resistance From Patients in China

BACKGROUND: The emergence of fosfomycin resistance and extended-spectrum β-lactamase (ESBL) genes is a serious threat to public health and a new challenge in shigellosis treatment. The purpose of this study was to identify fosfomycin resistance and characterize β-lactamase genes in fos-carrying isolates of Shigella flexneri from patients in China. METHODS: A total of 263 S. flexneri isolates were collected from 34 hospitals in the Anhui Province of China during September 2012-September 2015 and screened for fosA3, fosA, and fosC2 by PCR amplification and sequencing. The fos-carrying isolates were then screened for β-lactamase genes. The clonal relationships between fosA3-carrying isolates, the transmissibility of fosfomycin resistance, replicon types of plasmids carrying fosfomycin resistance genes and other associated resistance genes were investigated. RESULTS: Twenty-five of the 263 isolates (9.5%) showed resistance to fosfomycin, and 18 (6.8%) were positive for fosA3. None of the isolates was positive for fosA or fosC2. Seventeen of the isolates carrying fosA3 (94%) were CTX-M producers (seven CTX-M-55, five CTX-M-14, and five CTX-M-123), while three (16.7%) were TEM producers (TEM-1).Sixteen (88.9%) fosA3-carrying isolates exhibited multi-drug resistance. The replicon types of the 13 fosA3-carrying plasmids were IncF (n=13), IncHI2 (n=3), IncIl-Ir (n=2), and IncN (n=1). CONCLUSIONS: Our results indicated that fosA3 could spread through plasmids in S. flexneri isolates, along with the bla(CTX-M) and bla(TEM), which facilitate its quick dispersal. To the best of our knowledge, this is the first report of CTX-M-123-type ESBLs in S. flexneri isolates from patients in China.

Extended spectrum β‑lactamase producing Shigella flexneri serotype‑2 causing bacteremia in a patient with uncontrolled diabetes mellitus.

We report a case of Shigella flexneri serotype‑2 causing bacteremia in an elderly gentleman with uncontrolled diabetes mellitus, who had no other apparent risk factors. Antibiotic susceptibility testing revealed that the organism was a multidrug resistant extended spectrum beta‑lactamase producing strain, which was confirmed by molecular characterization. This rare case alerts both the clinician and microbiologist to a previously unaddressed risk factor of Shigella spp. causing bacteremia, as well as emerging resistant strains that are on the rise in immunocompromised patients.

Antisuero AA479: nuevo reactivo para la serotipificación de variantes atípicas se Shigella flexneri / AA479 antiserum: new reagent for the serotype characterization of atypical variants of Shigella flexneri

Shigella flexneri is divided into 13 serotypes based on the combination of antigenic determinants present in the O-antigen. A new O-antigen modification with phosphoethanolamine has been identified. The presence of this antigenic determinant (called E1037) is recognized by monoclonal antibody MASF IV-1. Given the increasing incidence of these new variants and the difficulty in supplying the monoclonal antibody to our country, we produced a polyclonal antiserum (AA479) through immunization with a S. flexneri Xv strain. The antiserum specificity was assessed by slide agglutination against isolates from clinical cases and a culture collection representing all Shigella serotypes. The results obtained demonstrated a 100% correlation between AA479 absorbed antiserum and monoclonal antibody MASF IV-1. The availability of AA479 antiserum in every public hospital in Argentina will allow us to identify atypical S. flexneri isolates in order to strengthen Shigella surveillance in our country and to compare with global epidemiological dat

Shigella flexneri se divide en al menos 13 serotipos sobre la base de la combinación de determinantes antigénicos presentes en el antígeno O. Se identificó una nueva modificación del antígeno O con fosfoetanolamina. La presencia de este determinante antigénico (denominado E1037) es reconocida por el anticuerpo monoclonal MASF IV-1. Teniendo en cuenta la incidencia creciente de estas nuevas variantes y la dificultad en la provisión del anticuerpo monoclonal para nuestro país, se elaboró un antisuero de tipo policlonal (AA479) mediante la inmunización con un cultivo de S. flexneri Xv. La especificidad del antisuero se evaluó por aglutinación en lámina con aislamientos clínicos y cultivos de colección, con lo que quedaron representados todos los serotipos de Shigella. Los resultados obtenidos demostraron una correlación del 100% entre el antisuero AA479 absorbido y el anticuerpo monoclonal MASF IV-1. La disponibilidad del antisuero AA479 en todos los hospitales públicos de Argentina permitirá identificar los aislamientos atípicos de S. flexneri; de esta forma se podrá fortalecer la vigilancia de Shigella en nuestro país y comparar con los datos epidemiológicos a nivel global

Synergistic inhibition of Lactobacillus acidophilus and Clostridium butyricum against Shigella flexneri in vitro / 中国药科大学学报

@#An agar diffusion method was used to investigate the antimicrobial activities of fermentation broth of Lactobacillus acidophilus(L. acidophilus), and Clostridium butyricum(C. butyricum)against Shigella flexneri(S. flexneri)infection in vitro. It was found that cell-free culture supernatants(CFCSs)of L. acidophilus and C. butyricum possessed remarkable synergistic anti-S. flexneri activity in vitro and the antimicrobial activity of the mixed culture was 17. 2% and 22. 4% greater, than single strains alone, respectively. Meanwhile, there was a symbiotic relationship between L. acidophilus and C. butyricum. The result showed that the biomass accumulation of the mixed culture reached 4. 27 g/L(DCW)and increased by 6. 0% and 30. 6% compared to the L. acidophilus and C. butyricum, respectively. Moreover, L. acidophilus and C. butyricum clearly inhibited S. flexneri adhesion to Caco-2 cells by 75. 8% and 81. 2%, and the combination of these two probiotic strains demonstrated the highest inhibition rate, reaching 84. 2%, while the viability of Caco-2 cells treated with L. acidophilus, C. butyricum or their combination was increased by 11. 5%, 12. 5% and 22. 9%, respectively. The synergistic effect of L. acidophilus and C. butyricum provided better protection against Shigella flexneri infection, which represents a promising alternative therapy for shigellosis.

Arabinose-controlled expression of htrA in Shigella flexneri through suicide plasmid-mediated homologous recombination / 军事医学

Objective To achieve arabinose-controlled expression of HtrA strain and detect the expression of HtrA protein.Methods Arabinose promoter with htrA100 was amplified from pACD-htrA vector by PCR and cloned into pGP704 vector.Then, Shigella flexneri 2a strain 301 was transferred with the recombinant plasmid pGD-htrA and an AraC-expression vector .The expressions of HtrA in whole-cell and periplasmic space were detected by Western blotting .Results The suicide plasmid-mediated homologous recombinant vector and the inducible HtrA expression strain were successfully constructed.Without arabinose,HtrA protein was hardly detected ,but in the presense of arabinose , HtrA protein could be detected in whole-cell lysate and in periplasmic space lysate by Western blot .Conclusion Homologous recombination using suicide plasmid can significantly knock down the expression of HtrA protein .After being induced with arabinose , HtrA protein can be expressed normally .

Transfer patterns of integron-associated and antibiotic resistance genes in S. flexneri during different time intervals in Tianjin, China.

Background: Shigella is one of the common genera of pathogens responsible for bacterial diarrhoea in humans. According to World Health Organisation (WHO), 800,000–1,700,000 patients in China were infected with Shigella spp. in 2000, and Shigella flexneri is the most common serotype (86%). Objectives: We investigated the transfer patterns of integron‑associated and antibiotic resistance genes in S. flexneri during different time intervals in the city of Tianjin in the People’s Republic of China. Materials and Methods: The integrase‑encoding and variable regions of the integrons of the bacterial strains were amplified by polymerase chain reaction (PCR), followed by gene sequencing. Fifty‑six S. flexneri strains, 32 of which were stored in our laboratory and the other 24 were isolated from tertiary hospitals in Tianjin during different time intervals, were tested for their sensitivity to 12 antibiotics by using the Kirby–Bauer antibiotic testing method (K‑B method). Results and Conclusion: Of the 32 strains of S. flexneri isolated from 1981 to 1983 and stored in our laboratory, class 1 integron was detected in 28 strains (87.50%), while 27 strains (84.37%) harboured an aminoglycoside resistance gene, aadA, in the variable region of their integrons. Class 1 integron was identified in 22 (91.67%) of the 24 S. flexneri strains isolated from 2009 to 2010, whereas the variable region and 3′‑end amplification were not present in any of the strains. Class 2 integron was not found in the 1981–1983 group (group A) of strains; although 19 (79.17%) of the 24 strains in the 2009–2010 group (group B) possessed class 2 integron, and the variable region of the integron harboured dfrA1 + sat1 + aadA1 genes, which, respectively, mediate antibiotic resistance to trimethoprim, streptothricin and streptomycin. Seventeen strains of the total 56 possessed both class 1 and 2 integrons. Strains belonging to group A were highly resistant to tetracycline, chloramphenicol and a combination of trimethoprim‑sulfamethoxazole; 65.63% of the strains were multi‑resistant to three or more antibiotics. In group B, the strains showed high resistance to ampicillin, trimethoprim‑sulfamethoxazole, piperacillin and tetracycline; 83.33% of the strains were multi‑resistant to three or more antibiotics. Class 1 and 2 integrons exist extensively in S. flexneri, and the 3′‑conserved segments of class 1 integron may have deletion or other types of mutations. Comparing the antibiotic and multi‑drug resistance of group A with that of group B, it is apparent that the antibiotic resistance and the incidence of genes that confer multi‑drug resistance have increased over the years in S. flexneri.

Biological characteristics and sequence typing analysis of S.flexneri 4c in Beijing, Shanghai and Shenyang of China / 军事医学

Objective To study the serotype , biochemical characteristics , virulence gene and multilocus sequence typ-ing(MLST) of S.flexneri 4c in Beijing, Shanghai and Shenyang .Methods Seventy-six strains of S.flexneri 4c isolated from stool samples which had been collected from above-mentioned cities of China were identified with Denka Seiken serum and MASF monoclonal serum .Biochemical characteristics of each strain were identified by API 20E test strip and PCR technology was used for detecting 12 pair virulence genes of S.flexneri.MLST was used to analyze the characteristics . Results The serum agglutination antigen structure of S.flexneri 4c was(Ⅳ:7,8).MASF:B+,Ⅳ:Ⅰ+,7 (8) +.S.flexneri 4c developed different results in biochemical reactions and carried different rates of virulence genes , respectively .The IND test positive rate was 17.11%; MEL weakly positive rate was 3.9%, and ARA test weakly positive rate was 22.37%. Virulence genes were carried at a rate of 89.47% -100%, MLST typing was ST245.Conclusion S.flexneri 4c with serum agglutination antigen structure (Ⅳ:7,8) is a new serotype of S.flexneri.The main biochemical reactions are glucose fermentation and mannitol decomposition .A variety of Shigella related virulence genes are carried .MLST generation is consistent,suggesting that the bacteria might have evolved from ST 270 cloning.

Functions of gene phoN1 in Shigella flexneri 2a:preliminary study / 军事医学

Objective To explore the function of gene phoN1 in Shigella flexneri.Method Using the λ-Red recombi-nant system, phoN1was knocked out from S.flexneri 2a strain 301.Comparative proteomics was performed to analyze the differences between mutant and wild-type strains in protein expression profiles .Sereny tests and competitive infection assays were carried out to compare the virulence of mutant and wild-type strains .Results The deletion mutant of phoN1 was suc-cessfully constructed .No significant difference between the two strains was found in the comparative proteomics analyses . The function of gene phoN1 might be unrelated to the invasion ability of S.flexneri according to the results of Sereny tests and competitive infection assays .Conclusion Gene phoN1 might be of no use for the in vitro survival and host cell invasion of S.flexneri.

Shigella flexneri Inhibits Intestinal Inflammation by Modulation of Host Sphingosine-1-Phosphate in Mice

Infection with invasive Shigella species results in intestinal inflammation in humans but no symptoms in adult mice. To investigate why adult mice are resistant to invasive shigellae, 6~8-week-old mice were infected orally with S. flexneri 5a. Shigellae successfully colonized the small and large intestines. Mild cell death was seen but no inflammation. The infected bacteria were cleared 24 hours later. Microarray analysis of infected intestinal tissue showed that several genes that are involved with the sphingosine-1-phosphate (S1P) signaling pathway, a lipid mediator which mediates immune responses, were altered significantly. Shigella infection of a human intestinal cell line modulated host S1P-related genes to reduce S1P levels. In addition, co-administration of S1P with shigellae could induce inflammatory responses in the gut. Here we propose that Shigella species have evasion mechanisms that dampen host inflammatory responses by lowering host S1P levels in the gut of adult mice.

HYPOXIC STRESS, HEPATOCYTES AND CACO-2 VIABILITY AND SUSCEPTIBILITY TO Shigella flexneri INVASION / Stress hipóxico, viabilidade e susceptibilidade de hepatócitos e células Caco-2 à invasão por Shigella flexneri

SUMMARY Inflammation due to Shigella flexneri can cause damage to the colonic mucosa and cell death by necrosis and apoptosis. This bacteria can reach the bloodstream in this way, and the liver through portal veins. Hypoxia is a condition present in many human diseases, and it may induce bacterial translocation from intestinal lumen. We studied the ability of S. flexneri to invade rat hepatocytes and Caco-2 cells both in normoxic and hypoxic microenvironments, as well as morphological and physiological alterations in these cells after infection under hypoxia. We used the primary culture of rat hepatocytes as a model of study. We analyzed the following parameters in normoxic and hypoxic conditions: morphology, cell viability, bacterial recovery and lactate dehydrogenase (LDH) released. The results showed that there were fewer bacteria within the Caco-2 cells than in hepatocytes in normoxic and hypoxic conditions. We observed that the higher the multiplicity of infection (MOI) the greater the bacterial recovery in hepatocytes. The hypoxic condition decreased the bacterial recovery in hepatocytes. The cytotoxicity evaluated by LDH released by cells was significantly higher in cells submitted to hypoxia than normoxia. Caco-2 cells in normoxia released 63% more LDH than hepatocytes. LDH increased 164% when hepatocytes were submitted to hypoxia and just 21% when Caco-2 cells were in the same condition. The apoptosis evaluated by Tunel was significantly higher in cells submitted to hypoxia than normoxia. When comparing hypoxic cells, we obtained more apoptotic hepatocytes than apoptotic Caco-2 cells. Concluding our results contribute to a better knowledge of interactions between studied cells and Shigella flexneri. These data may be useful in the future to define strategies to combat this virulent pathogen. .

RESUMO A inflamação causada por Shigella flexneri pode causar danos à mucosa do cólon e morte celular por necrose e apoptose. Esta bactéria pode atingir a corrente sanguínea por esta via e o fígado através da veia porta. A hipóxia é uma condição presente em muitas doenças humanas, podendo induzir a translocação bacteriana a partir do lúmen intestinal. Nós estudamos a capacidade de S. flexneri invadir hepatócitos de rato e células Caco-2 nos microambientes de normóxia e hipóxia, bem como as alterações morfológicas e fisiológicas dessas células após a infecção sob hipóxia. Utilizamos a cultura primária de hepatócitos de ratos como modelo de estudo. Nós analisamos os seguintes parâmetros em condições de normóxia e hipóxia: morfologia, viabilidade celular, recuperação bacteriana e liberação de lactato desidrogenase (LDH). Os resultados mostraram menor quantidade de bactérias dentro das células Caco-2 do que em hepatócitos em condições de normóxia e hipóxia. Nós observamos que quanto maior foi a multiplicidade de infecção (MOI), maior também foi a recuperação bacteriana em hepatócitos. A condição hipóxica foi capaz de diminuir a recuperação de bactérias dos hepatócitos. A citotoxicidade avaliada pela liberação de LDH foi significativamente maior em células submetidas à hipóxia do que normóxia. As células Caco-2 em normóxia produziram 63% mais LDH do que os hepatócitos. O LDH aumentou 164% quando os hepatócitos foram submetidos à hipoxia e apenas 21% quando as células Caco-2 estavam na mesma condição. A apoptose avaliada por TUNEL foi significativamente ...

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.

Drug resistant Shigella flexneri in & around Dibrugarh, north-east India.

Background & objectives: Shigella flexneri is the most common species of Shigella causing diarrhoea and dysentery in Asia including India. Multidrug resistance in Shigella species has been reported worldwide and there is rising concern regarding development of fluoroquinolone resistance. This study was undertaken to find out the resistance pattern of Sh. flexneri, the commonest shigella isolated in Dibrugarh, north east India, including detection of fluoroquinolone resistance and extended spectrum beta lactamases. Methods: Stool samples collected from patients of diarrhoea and dysentery were tested for bacterial enteropathogens. Strains of Shigella species were confirmed by biochemical tests. Speciation was done using commercially available polyvalent antiserum. Antimicrobial susceptibility test was performed by Kirby Bauer disc diffusion method against 18 different antibiotics. Extended spectrum beta lactamase (ESBL) detection was done by disc approximation test as well as combination disc method and minimum inhibitory concentrations (MIC) of different antibiotics were also measured. Results: Multidrug resistance in Sh. flexneri was found to be common (90.2%) and the commonest phenotypic multi-drug resistance profile was ampicillin-tetracycline-co-trimoxazole-nalidixic acid. High resistance to nalidixic acid was detected in 90.3 per cent isolates (MIC >240 μg/ml) and ciprofloxacin resistance was seen emerging in this region (11.2%, MIC >4 μg/ml). Present of ESBL was phenotypically confirmed in two cases. Besides the fluoroquinolones, chloramphenicol, piperacillin-tazobactum and the third generation cephalosporins were effective in 87-100 per cent of the isolates. Interpretation & conclusions: Our study showed high resistance (MIC >240 μg/ml) against nalidixic acid in Sh. flexneri isolates. Ciprofloxacin resistance is also emerging in this region. Shigellosis due to ESBL carrying Shigella can become a serious threat to public health. Guidelines for therapy should be monitored and modified based on regional reports of resistance to antimicrobial agents.

Comparative analysis of the genomes of Shigella dysenteriae type 2 & type 7 isolates.

Background & objectives: The four species of the genus Shigella, namely, S. dysenteriae, S. flexneri, S. boydii and S. sonnei cause a wide spectrum of illness from watery diarrhoea to severe dysentery. Genomes of these four species show great diversity. In this study, NotI, XbaI or I-CeuI restriction enzyme digested genomes of two Shigella dysenteriae isolates belonging to the serotypes 2 and 7 were extensively analyzed to find their relatedness, if any, with the whole genome sequenced strains of S. dysenteriae type 1 and S. flexneri type 2a. Methods: Pulsed-field gel electrophoresis (PFGE) technique was used to determine the diversity of Shigella genomes by rapid construction of physical maps. DNA end labelling, Southern hybridization and PCR techniques were also applied for mapping purposes. Results: The intron-coded enzyme I-CeuI cuts the bacterial genome specifically at its rrn operon. PFGE of I-CeuI digested S. dysenteriae genomes were found to carry seven rrn operons. However, I-CeuI profiles showed distinct restriction fragment polymorphism (RFLP) between the isolates as well as with the whole genome sequenced isolates. Further studies revealed that the genome sizes and I-CeuI linkage maps of the S. dysenteriae type 7 and type 2 isolates were similar to that of S. dysenteriae type 1 and S. flexneri type 2a genomes, respectively. Interpretation & conclusions: Our findings indicate that the type 7 and type 1 isolates of S. dysenteriae were probably evolved from a same precursor, while the type 2 and S. flexneri type 2a were probably evolved and diversified from a common progenitor.

Cefotaximase and AmpC-producing Shigella flexneri in case of dysentery from southern India.

Diarrhoea and dysentery caused by Shigella spp. are major public health concerns. Emerging multidrug resistance (MDR) in this pathogen further complicates this disease. Extended spectrum β-lactamases (ESBLs) have been described in this pathogen, which significantly compromises the treatment options for shigellosis. The usual ESBLs seen are sulfhydryl variable (SHV)-type; cefotaximases (CTX-M) are very uncommonly detected. Here, we report a CTX-M type and AmpC-producing Shigella flexneri from a three-year-old boy residing in Central Kerala, South India.

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.