Rapid identification of Staphylococcus aureus, Vibrio parahaemolyticus and Shigella sonnei in foods by solid phase microextraction coupled with gas chromatography-mass spectrometry.

A novel approach for rapid identification of three foodborne pathogens including Staphylococcus aureus, Vibrio parahaemolyticus and Shigella sonnei in foods by solid phase microextraction (SPME) coupled with gas chromatography-mass spectrometry (GC-MS) was established. After cultivation 24, 18 and 20 h for Staphylococcus aureus, Vibrio parahaemolyticus and Shigella sonnei, respectively, the microbial volatile organic compounds (MVOCs) were extracted with a SPME device equipped with divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) coated fibers. The DB-1701P column was applied for separation of MVOCs. A total of 17, 13 and 14 volatile organic compounds were identified as characteristic MVOCs of Staphylococcus aureus, Vibrio parahaemolyticus and Shigella sonnei, respectively. Similarity of the MVOC chromatographic fingerprints for the bacteria were calculated and compared, and the results showed that the established method is stable, reproducible, accurate and has the potential to identify the three bacteria in food samples.

Detection of Shigella sonnei in a respiratory specimen in a patient with subacute atypical pneumonia.

BACKGROUND: Pneumonia caused by shigellosis with or without typical dysentery in immunocompetent patients is an uncommon entity. CASE REPORT: We describe a case of pneumonia in an immunocompetent, previously healthy middle-aged man from Switzerland without relevant travel history which was presumably caused by Shigella sonnei. He was originally admitted for suspected lung cancer. The clinical picture was remarkable as the patient presented with cough and purulent sputum production, but otherwise no classical signs of pneumonia. Furthermore, there was no diarrhoeal episode in the recent history. It is an uncommon presentation of shigellosis in an immunocompetent person without underlying severe predisposing conditions. CONCLUSION: We report an unusual identification of S. sonnei as the only identified pathogen from respiratory specimens, which we therefore consider the most likely etiology of this subacute atypical pneumonia. This case illustrates the importance of a complete work-up in a patient whose suspected malignancy could not be proven.

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.

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.

Shigella sonnei bacteremia: two adult cases and review of the literature.

Shigella sonnei bacteremia in adult patients is rare. We present 2 cases from our center, and 7 others from the literature are reviewed in detail. Diabetes mellitus and malignancy are frequent predisposing conditions. Despite severe illness at presentation, our patients achieved good outcomes with prompt initiation of antimicrobial therapy.

Epidemiological characterization of resistance and PCR typing of Shigella flexneri and Shigella sonnei strains isolated from bacillary dysentery cases in Southeast Brazil

Shigella spp are Gram-negative, anaerobic facultative, non-motile, and non-sporulated bacilli of the Enterobacteriaceae family responsible for "Shigellosis" or bacillary dysentery, an important cause of worldwide morbidity and mortality. However, despite this, there are very few epidemiological studies about this bacterium in Brazil. We studied the antibiotic resistance profiles and the clonal structure of 60 Shigella strains (30 S. flexneri and 30 S. sonnei) isolated from shigellosis cases in different cities within the metropolitan area of Campinas, State of São Paulo, Brazil. We used the following well-characterized molecular techniques: enterobacterial repetitive intergenic consensus, repetitive extragenic palindromic, and double-repetitive element-polymerase chain reaction to characterize the bacteria. Also, the antibiotic resistance of the strains was determined by the diffusion disk method. Many strains of S. flexneri and S. sonnei were found to be multi-resistant. S. flexneri strains were resistant to ampicillin in 83.3 percent of cases, chloramphenicol in 70.0 percent, streptomycin in 86.7 percent, sulfamethoxazole in 80.0 percent, and tetracycline in 80.0 percent, while a smaller number of strains were resistant to cephalothin (3.3 percent) and sulfazotrim (10.0 percent). S. sonnei strains were mainly resistant to sulfamethoxazole (100.0 percent) and tetracycline (96.7 percent) and, to a lesser extent, to ampicillin (6.7 percent) and streptomycin (26.7 percent). Polymerase chain reaction-based typing supported the existence of specific clones responsible for the shigellosis cases in the different cities and there was evidence of transmission between cities. This clonal structure would probably be the result of selection for virulence and resistance phenotypes. These data indicate that the human sanitary conditions of the cities investigated should be improved.

[Alibi verification and the PCR method to estimate the source of epidemic for a few notified cases of S. sonnei].

OBJECTIVES: A few culture-confirmed cases of S. sonnei have been notified from Korean hospitals. The source of epidemic can't be firmly determined in such cases because of the rarity of this illness in the local communities and the timing of the outbreaks. The objective of this study is to estimate the source of epidemic by investigating the patients' lifestyles. METHODS: Alibi verification was used to access the presumed source of the epidemic. PCR (Polymerase Chain Reaction) was used to rapidly detect the genes of Shigella in water specimens. RESULTS: The common lifestyle trait among the Shigella-infected patients was connected with Mt. Martyr in J city, Korea. The first patient's son had gone on a pilgrimage to Mt. Martyr with 41 friends and he had only eaten rice cakes on April 5th; the second patients had visited Mt. Martyr with their mother for a picnic on April 12th; the third patient had visited Mt. Martyr with 22 friends for a pilgrimage and the patient had only drunk holy water on April 13th. Therefore, the holy water of Mt. Martyr was reckoned to be the source of the epidemic. PCR detected the genes of Shigella two days before the S. sonnei was confirmed. CONCLUSION: The patients' lifestyles for 7 days before the onset of symptoms should be determined in terms of time, place and contacted people to find the source of infection when cases with food poisoning are seen in the hospital setting.

Shigella sonnei meningitis due to interleukin-1 receptor-associated kinase-4 deficiency: first association with a primary immune deficiency.

BACKGROUND: Inherited interleukin-1-receptor-associated kinase-4 (IRAK-4) deficiency is a recently described immunodeficiency associated with pyogenic bacterial infections and a poor inflammatory response. Shigella sonnei is generally associated with outbreaks of rectocolitis in developed countries, but systemic illnesses have occasionally been reported. An underlying primary immunodeficiency has not been found in such cases before now. METHODS: We report the clinical and immunological features of a patient with IRAK-4 deficiency who has a history of systemic shigellosis in addition to other infections. RESULTS: The patient has a history of Staphylococcus aureus, Streptococcus pneumoniae, and Pseudomonas aeruginosa infections during childhood and an episode of S. sonnei septicemia and meningitis at 10 years of age. This patient's history contrasted with that of other individuals infected concurrently by the same organism. Of note, these episodes were not accompanied by acute phase responses in our patient. Subsequently, the patient has had more episodes of staphylococcal disease, but no systemic illnesses. The patient is now 30 years old and has been doing well since prophylactic antibiotic treatment was stopped 4 years ago. DISCUSSION: To our knowledge, this is the first report of a case of systemic shigellosis in a person with a primary immunodeficiency, expanding the spectrum of infections associated with IRAK-4 deficiency. Thus, immunity mediated by IRAK-4 seems to be crucial for both the containment of and the inflammatory response to S. sonnei infection in the intestinal mucosa. IRAK-4 deficiency and related disorders should be considered in patients with systemic shigellosis.

Experimental study on the antibacterial effect of origanum volatile oil on dysentery bacilli in vivo and in vitro.

To observe the germistatic and germicidal effects of origanum volatile oil (OVI) on the dysentery bacteria, the abdominal cavity of mice was infected with Shigella sonne (Sh. sonnei) and Shigella flexneri (Sh. flexneri) F2a. After OVI was given to the mice via gastric lavage, the effects of OVI on the infected mice were observed. The minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) for dysentery bacteria were determined in vitro. The results showed that origanum volatile oil showed obvious protective effect on mice infected with Sh. sonnei and Sh. flexneri F2a and it had germistatic and germicidal effects on dysentry bacteria. We are led to conclude that origanum volatile oil is an effective medicine against the infection of dysentery bacteria.

Alternative anaerobic enrichments to the bacteriological analytical manual culture method for isolation of Shigella sonnei from selected types of fresh produce.

Alternative methods of reducing oxygen during anaerobic enrichment in the Bacteriological Analytical Manual (BAM) Shigella culture method were evaluated and compared to the current and less practical GasPak method. The alternative anaerobic methods included the use of reducing agents in Shigella broth and reducing culture container headspace volume to minimize atmospheric effects on oxygen concentration in Shigella broth during enrichment. The reducing agents evaluated were sodium thioglycollate, L-cystine, L-cysteine, titanium(III) citrate, and dithiothreitol, each at concentrations of 0.1, 0.05, and 0.01%. The use of Oxyrase for Broth with the enrichment medium (Shigella broth) was evaluated at concentrations of 10, 20 and 30 microL/mL. Recoveries of chill- and freeze-stressed S. sonnei strains 357 and 20143 were determined with each anaerobic method, including the GasPak method, using inoculation levels ranging from 10(0)to 10(3) cells. For each anaerobic method, strain, inoculation level, and stress type, 5 replicate enrichments were evaluated by streaking to MacConkey agar for isolation. The numbers of cultures with each method from which S. sonnei was isolated were used to compare the alternative anaerobic methods to the GasPak method. The alternative anaerobic method with which chill- and freeze-stressed S. sonnei strains 357 and 20143 were isolated most consistently was the use of Oxyrase for Broth in Shigella broth at a concentration of 20 microL/mL. This method was compared to the GasPak anaerobic method in evaluations on the recovery of S. sonnei strains 357 and 20143 from artificially contaminated test portions of parsley, cilantro, green onions, strawberries, carrots, and celery. A third anaerobic method included the use of 0.5 cm mineral oil overlay on cultures containing Oxyrase for Broth at concentrations of 20 microL/mL. Recovery rates of strain 357 were significantly greater (p < 0.05) with the GasPak method than with Oxyrase for Broth, with and without the 0.5 cm mineral oil overlay, for test portions of parsley, cilantro, and celery. When Oxyrase for Broth was used with Shigella broth, strain 357 was isolated at higher rates from all produce types, except cilantro, when 0.5 cm mineral oil overlay was applied to enrichment cultures. The use of mineral oil overlay with Oxyrase for Broth also improved recovery of strain 20143 from test portions of all produce types except green onion and strawberries. These differences were significant (p < 0.05) with parsley, carrots, and cilantro (1 of 2 evaluations). No statistically significant differences (p > 0.05) between the GasPak and Oxyrase for Broth anaerobic methods occurred when mineral oil overlay was used with Oxyrase for Broth. The use of Oxyrase for Broth with a 0.5 cm mineral oil overlay is a practical alternative for anaerobic enrichment with the BAM method in the analysis of some produce types. Differences in recovery among the different produce types and methods occurred between S. sonnei strains 357 and 20143, emphasizing the need for additional S. sonnei strains in future evaluations.

Patrones de sensibilidad in vitro y comportamiento clínico de shigella / Susceptibility patterns and clinical presentation of shigella

Shigella mantiene un importante lugar como causa de diarrea en niños con aumento de su resistencia antimicrobiana en los últimos años, lo que dificulta la elección de terapia empírica en cuadros disentéricos. Se estudió la susceptibilidad antimicrobiana in vitro a 163 cepas aisladas entre 1997 y 1999. S. sonnei representó el 63 por ciento de las cepas aisladas. Se observó aumento en los patrones de resistencia de Shigella a los antimicrobianos tradicionales. La resistencia global de las cepas alcanzó a 95 por ciento para ampicilina, 84 por ciento para cloranfenicol, 43,6 por ciento para cotrimoxazol y 3,7 por ciento para furazolidona; no hubo resistencia a ciprofloxacina. De 57 niños hospitalizados por shigelosis, 82,5 por ciento tenían sobre 2 años de edad. Todos presentaron fiebre, 56 por ciento disentería y 8,8 por ciento convulsiones. Seis pacientes con evolución tórpida recibieron ciprofloxacina con éxito clínico. Ciprofloxacina representa una alternativa a evaluar como terapia empírica en niños con disentería de causa bacteriana. Es necesario mantener vigilancia local en la susceptibilidad antimicrobiana de Shigella a fin de guiar su terapia específica

Vigilancia de la resistencia a los antibacterianos en Argentina: programa WHONET, 1995-1996 / Monitoring antimicrobial resistance in Argentina: the WHONET program, 1995-1996

La Organización Mundial de la Salud ha puesto en marcha un programa para la vigilancia de la resistencia a los antibacterianos, denominado WHONET, que se desarrolló en Argentina mediante una red de 23 laboratorios de instituciones hospitalarias públicas y privadas sometidos a programas nacionales e internacionales de control de calidad. Entre enero de 1995 y diciembre de 1996 se determinó por el método de difusión en agar la sensibilidad a los antibacterianos de 16.073 aislados clínicos consecutivos, siguiendo las recomendaciones del Comité Nacional de Estándares para Laboratorios Clínicos (National Committee for Clinical Laboratory Standards: NCCLS) de los Estados Unidos de América. Más de la mitad de los aislados urinarios de Escherichia coli fueron resistentes a la ampicilina, y más de 30 por ciento a la trimetoprima-sulfametoxazol. Cuando se comparó la sensibilidad de los aislados urinarios de pacientes ambulatorios y hospitalizados, se observó una marcada diferencia en los perfiles de actividad (porcentaje de microorganismos resistentes aislados en pacientes hospitalizados frente a pacientes ambulatorios) de la gentamicina (8 por ciento frente a 2 por ciento), la norfloxacina (6 por ciento frente a 2 por ciento) y las cefalosporinas de tercera generación (18 por ciento frente a 10 por ciento). Los aislados de Klebsiella pneumoniae recuperados de hemocultivos presentaron resistencia a las cefalosporinas de tercera generación y a la gentamicina en 71 y 60 por ciento de los casos, respectivamente. La proporción de Staphylococcus aureus resistentes a la oxacilina fue de 39 por ciento. Cerca de la mitad de los aislados de Enterococcus spp. presentaron resistencia de alto nivel a los aminoglucósidos, pero no se detectó resistencia los glicopéptidos. En nuestro medio, la ampicilina y la trimetoprima-sulfametoxazol no fueron apropiadas para el tratamiento de las diarreas; Shigella flexneri presentó mayor porcentaje de aislados resitentes a ambos fármacos (87 y 74 por ciento, respectivamente) que Shigella sonnei (47 y 71 por ciento, respectivamente). Se detectó resistencia a las cefalosporinas de tercera generación en 40 por ciento de los aislados de Salmonella spp. recuperados en hospitales pediátricos. En casos de meningitis bacteriana, las tasas de resistencia de Streptococcus pneumoniae a la penicilina (18 por ciento) y de Haemophilus influenzae a la ampicilina (19 por ciento) se situaron en el rango intermedio de las descritas en países

Comparative value of colonic biopsy and intraluminal fluid culture for diagnosis of bacterial acute colitis in immunocompetent patients. Infectious Colitis Study Group.

We compared the yield of intraluminal fluid culture to that of biopsy specimens obtained during colonoscopy for the diagnosis of bacterial colitis in 93 immunocompetent patients with a recent episode of diarrhea and macroscopic lesions of colitis. Stool culture findings were also available for 68 patients. At least one bacterial pathogen was isolated from the biopsy specimen, intraluminal fluid, or stool from 48 patients (51.6%). Salmonella species, Clostridium difficile, Klebsiella oxytoca, Shigella species, and Campylobacter species were recovered from 16 (17.2%), 15 (16.1%), 8 (8.6%), 7 (7.5%), and 4 (4.3%) of the patients, respectively. One Shigella species and one K. oxytoca strain were isolated from biopsy specimens but not from intraluminal fluid, and intraluminal fluid was the only positive specimen in 12 cases (yielding 1 Salmonella species, 2 Shigella species, 2 K. oxytoca, and 7 C. difficile isolates). In nine cases out of 10, toxin B was detected only in intraluminal fluid. A correlation of 91.2% was observed between stool and intraluminal fluid cultures for Salmonella, Shigella, and Campylobacter species isolations. Culture of biopsy specimens adds little to the diagnosis of infectious colitis, and stools and intraluminal fluids appear to have comparable value.

Frecuencia y biodiversidad de algunas bacterias enteropatógenas aisladas en niños con síndrome diarreico agudo / Frequency and biodiversity of some enteropathogenic bacteria recovered from children with acute diarrheic syndrome

El estudio etiológico de la diarrea aguda en el niño se ve limitado por las técnicas actualmente disponibles con fines clínicos. La aplicación de técnicas de biología molecular en el análisis de deposiciones permite incrementar la detección de enteropatógenos y una caracterización fenotípica más acabada de las cepas aisladas permite describir mejor su diversidad y caracterizar epidemiológicamente los episodios observados en cada temporada estival. En un estudio piloto efectuado en la ciudad de Concepción, se aplicaron en el estudio etiológico de la diarrea en niños entre 0 y 4 años de edad consultantes en un servicio de urgencia, las técnicas convencionales de cultivo e identificación por pruebas bioquímicas según Edwards y Ewing, la búsqueda de genes de virulencia de Escherichia coli enterohemorrágica más el análisis de serotipo, biotipo, antibiotipo y perfil plasmidial de las cepas enteropatógenas aisladas. En 32 (25,3 por ciento) de 127 niños con diarrea de edad entre 5 meses y 4 años de detectó la frecuencia de los siguientes enteropatógenos: Shigella sonnei 13,4 por ciento Shigella flexneri 6,3 por ciento, Yersinia enterocolitica 2,4 por ciento, Shigella boydii 0,8 por ciento, Salmonella typhimurium 1,6 por ciento y Salmonella hadar 0,8 por ciento. La frecuencia de aislamiento aumentó en relación al aumento de la edad desde 0 por ciento en el grupo etario de 4 a 5 meses, 6,3 por ciento en el de 6 a 11 meses, 33,1 por ciento en el de 12 a 23 meses, hasta 68,7 por ciento en el grupo de 24 a 47 meses. Shigella spp. fueron las de mayor frecuencia relativa de aislamiento con 81,1 por ciento. El rendimiento de las determinaciones feno y genotípicas para estudio de biodiversidad fue variable en las especies. Las 8 cepas de S. flexneri se diferenciaron en 6 grupos en base a 3 serotipos, 5 antibiotipos y 5 perfiles plasmidiales. Las 17 cepas de S. sonnei se discriminaron en 11 grupos determinados preferentemente por los patrones plasmidiales. La amplificación aleatoria mediante RAPD en S. flexneri y S. sonnei no aportó mayor grado de biodiversidad que la establecida por las otras determinaciones. El antibiotipo y perfil plasmidial fueron útiles en discriminar en 2 grupos las 3 cepas de Y. enterocolitica, marcadores que además permitieron sugerir que las S. typhimurium aisladas serían una misma cepa

Aislamientos de Shigella y Salmonella durante el período 1990-1994 / Isolation of Shigella and Salmonella during the period 1990-1994

En el siguiente trabajo se comunican los aislamientos de Shigella y Salmonela en pacientes con diarreas agudas que fueron atendidos en el Hospital de Niños Ricardo Gutierrez de la ciudad de Santa Fe en el período 1990-1994. Shigella prevaleció en cada uno de los años estudiados con respecto a Salmonella, y el serogrupo predominante fue flexneri. La recuperación de Salmonella fue similar en cada año, debiéndose destacar un brote intrahospitalario a Salmonella typhimurium. Es importante conocer los agentes más frecuentes para que las medidas de control sean dirigidas y permitan orientar investigaciones futuras relacionadas con las enfermedades diarreicas

Characteristics of Shigella sonnei infection of volunteers: signs, symptoms, immune responses, changes in selected cytokines and acute-phase substances.

Shigella sonnei infection resulting from oral administration of 500 colony-forming units was followed in 11 volunteers with the objective of studying the immune response and pathogenesis. Characterization of infection included recording of signs and symptoms, excretion of S. sonnei in stool, measurement of humoral tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta), interferon-gamma (IFN-gamma), C-reactive protein, IL-2 receptor, soluble CD8, antibody-antigen complexes, and endotoxin. Measurements were also made of the immune response including lymphocytes secreting antibody to S. sonnei O antigen and serum antibody to this antigen. Six of the volunteers developed typical shigellosis with excretion of bacteria in stool and systemic signs and symptoms, three excreted bacteria but did not show illness, and two showed no evidence of infection or illness. Shigellosis was characterized by excretion in stool of S. sonnei beginning on average 1.3 days after ingestion. Excretion of S. sonnei (mean of time of the first positive cultures) was followed in sequence by the onset of increases in TNF-alpha (10 hr), liquid stools (14 hr), fever and dysentery (18 hr), IFN-gamma (22 hr), and C-reactive protein (34 hr). A S. sonnei-specific immune response was demonstrated somewhat later, between days 4 and 7 postinfection by antibody-secreting cells, and between days 7 and 14 postinfection by humoral antibody. Shigellosis was not associated with increased humoral IL-1 beta, endotoxin, or antigen-antibody complexes.