¿La detección de toxinas de Clostridioides difficile es necesaria cuando se detecta la enzima glutamato deshidrogenasa? / Is Clostridioides difficile toxins detection necessary when the glutamate dehydrogenase enzyme is detected?

Resumen Introducción: Clostridioides difficile causa diarrea y colitis pseudomembranosa. Su diagnóstico se realiza con la detección de glutamato-deshidrogenasa (GDH) o las toxinas A y B y se confirma con pruebas de amplificación de ácidos nucleicos. Objetivo: Definir si la determinación de GDH es redundante a la de las toxinas. Métodos: Estudio observacional retrospectivo de muestras fecales de pacientes con sospecha de infección por Clostridioides difficile. Las toxinas y GDH se determinaron mediante inmunocromatografía. Se realizó una simulación bayesiana con los cocientes de probabilidad; se consideró significativo un valor de p < 0.05. Resultados: Se analizaron 329 resultados de GDH y toxinas A y B. Se encontró una prevalencia de infección de Clostridioides difficile de 18.2 %. La sensibilidad y especificidad de la prueba de GDH fue de 0.90 y 0.89, respectivamente. El cociente de probabilidad positivo fue de 8.9 y el negativo, de 0.11. Conclusiones: Un resultado negativo de GDH disminuye considerablemente la probabilidad de infección, pero no la descarta. La detección de toxinas de Clostridioides difficile puede ser necesaria en instituciones donde la amplificación de ácidos nucleicos no es económica o accesible.

Abstract Introduction: Clostridioides difficile causes diarrhea and pseudomembranous colitis. Its diagnosis is made with glutamate dehydrogenase (GDH) or toxins A and B detection and is confirmed with nucleic acid amplification tests. Objective: To define if GDH determination is redundant to that of toxins. Methods: Retrospective, observational study in diarrheal stools of patients with suspected Clostridioides difficile infection. Toxins and GDH were determined by immunochromatography. Bayesian simulation was performed with likelihood ratios; a p-value < 0.05 was regarded as significant. Results: 329 GDH and toxin A and B results were analyzed. Clostridioides difficile infection prevalence was 18.2 %. Sensitivity and specificity of the GDH test were 0.90 and 0.89, respectively. Positive likelihood ratio was 8.9, and negative was 0.11. Conclusions: A negative GDH result considerably reduces the probability of infection but does not rule it out. Clostridioides difficile toxins detection may be necessary in institutions where nucleic acid amplification is not affordable or accessible.

Clinical and genetic characteristics analysis of Chinese children with glutamate dehydrogenase type of congenital hyperinsulinemia / 中华胰腺病杂志

Objective@#To analyze the clinical features and genetic characteristics of Chinese children with glutamate dehydrogenase type of congenital hyperinsulinism (GDH-HI).@*Methods@#Pedigrees with 10 GDH-HI children admitted to Beijing Children′s Hospital from February 2008 to December 2018 were selected as subjects. Clinical features, the detection of pathogenic genes and follow-up data were retrospectively analyzed. Polymerase chain reaction DNA (PCR-DNA) direct sequencing method and second generation sequencing technique were used to analyze the GLUD1 genetic sequences of 10 GDH-HI children and their relatives.@*Results@#Of the 10 GDH-HI children, 9 had normal birth weight and 1 was a giant. Nine patients were accompanied by asymptomatic hyperammonemia, and one had normal blood ammonia. 9 had ever been treated with diazoxide, which was all effective. All 10 children carried GLUD1 gene mutations, 5 patients carried c. 965C>T (p.R322H) GLUD1 gene mutation, and the remaining 5 cases carried c. 1388A>T (p.N463I), c. 1495C>A(p.G499C), c. 1493C>T(p. S498L), c. 1519G>A(p.H507Y) and c. 1388A>G(p.N463S), respectively. 9 cases (90%) had de novo mutations, and 1 case had paternal autosomal dominant inheritance. 8 children were followed up in long term. One child had spontaneous remission in 8 years after being diagnosed, and seven patients required long-term oral diazoxide to maintain normal blood glucose levels, two of whom had epilepsy.@*Conclusions@#The birth weight of children with GDH-HI in China was usually normal. A small number of GDH-HI children had normal serum ammonia levels. Most of the GLUD1 gene mutations in GDH-HI children in China were de novo mutations, among which the GDH p. R322H mutation was a hot spot mutation in Chinese children with GDH-HI. Most of GDH-HI children were diazoxide-responsive. As the disease progresses, some children may have epilepsy, and a few children have a tendency to relieve by themselves.

Clinico-microbiological analysis of toxigenic clostridium difficile from hospitalised patients in a tertiary care hospital, Mangalore, Karnataka, India

Purpose: Prevalence of Clostridium difficile, an anaerobic, Gram-positive, spore-forming bacillus, is very much underestimated in India. The present study was intended to assess the burden of toxigenic C. difficile in hospitalised patients with clinically significant diarrhoea and analysis of their clinical picture. Materials and Methods: This cross-sectional study was conducted in a tertiary care teaching hospital, South India, from January 2012 to December 2014. Stool samples were collected consecutively from 563 inpatients from various wards. The prevalence of toxigenic C. difficile was determined by toxigenic culture and a two-step algorithm. The clinical spectrum of these patients was also analysed. Associated pathogens were identified using standard procedures. Statistical analysis was done by frequency, percentage, Chi-square test and z-test. Results: Out of the 563 stool samples analysed, the prevalence of toxigenic C. difficile was 12.79% and that of non-toxigenic C. difficile was 10.83%. The prevalence of toxigenic C. difficile among oncology patients was highly significant (HS). Antibiotic treatment, prolonged hospital stay and underlying diseases/conditions were the risk factors which were HS, and fever was the significant clinical feature among the patients. Escherichia coli was the predominant associated pathogen isolated (18.47%). Conclusion: The presence of toxigenic C. difficile in our locality is a matter of concern. Constant supervision, appropriate treatment and preventive measures are crucial in controlling C. difficile infection.

Simultaneous Detection of Clostridioides difficile Glutamate Dehydrogenase and Toxin A/B: Comparison of the C. DIFF QUIK CHEK COMPLETE and RIDASCREEN Assays

Various commercial assays have recently been developed for detecting glutamate dehydrogenase (GDH) and/or toxin A/B to diagnose Clostridioides difficile infection (CDI). We compared the performance of two assays for the simultaneous detection of C. difficile GDH and toxin A/B, using 150 stool samples: C. DIFF QUIK CHEK COMPLETE (QCC; TechLab, Blacksburg, VA, USA) and RIDASCREEN Clostridium difficile GDH (RC-GDH) and Toxin A/B (RC-Toxin A/B; R-Biopharm, Darmstadt, Germany). For GDH detection, QCC and RC-GDH showed satisfactory sensitivity (95.7% and 94.3%, respectively) and specificity (92.5% and 93.8%, respectively) compared with C. difficile culture. For toxin A/B detection, QCC showed higher sensitivity than RC-Toxin A/B (60.0% vs 33.3%, P < 0.001) compared with toxigenic C. difficile culture. When the results of QCC or RC-GDH+RC-Toxin A/B were used as the first step of a two-step algorithm for diagnosing CDI, QCC permitted more accurate discrimination than RC of positive or negative results for CDI (77.3% and 65.3%, respectively). QCC is useful for the simultaneous detection of C. difficile GDH and toxin A/B as a part of the two-step algorithm for diagnosing CDI.

Correlation of glutamate dehydrogenase with several tumors / 生物工程学报

Most organisms contain glutamate dehydrogenase (E.C. 1.4.1.2-1.4.1.4). In eukaryotes, the enzyme is mainly present in mitochondria. This enzyme plays a vital role in the metabolism of nitrogen and carbon and the signaling pathway. Studies have found that glutamate dehydrogenase has a certain relationship with the occurrence and development of tumors, which is significant for tumor research, but reviews on its relationship with human tumors are rare. This review summarized the relationship between glutamate dehydrogenase and breast cancer, glioma, colorectal cancer and ovarian cancer, etc, thus providing assistance for related research.

Incidence, epidemiology and control of Clostridium difficile infection in a tertiary care private hospital in India

Purpose: Clostridium difficile infection (CDI) is a serious healthcare-associated infection (HAI) now being increasingly reported from hospitals across India. However, there is a paucity of data on the incidence of and impact of control measures on CDI in India. Materials and Methods: This is a retrospective study conducted at a tertiary care hospital in Mumbai from January 2016 to December 2017. All patients with healthcare-onset diarrhoea were tested for C. difficile by glutamate dehydrogenase (GDH)/toxin assay or nucleic acid amplification test (NAAT). CDI was defined as either GDH and toxin positive or NAAT positive. The incidence of CDI was calculated per 1000 patient days. Demographic features of patients with CDI including age, sex, duration of hospitalisation before onset of CDI, antibiotic use and treatment administered were summarised. Results: A total of 67 patients had CDI in the study period with a mean incidence of 0.2/1000 patient days. A halving of the CDI incidence was seen after intensification of the CDI prevention bundle. The mean age of affected patients was 64 years and CDI occurred at a median duration of 2 weeks after hospitalisation. Eighty-seven per cent of the patients were on antibiotics at the time of diagnosis of CDI. The crude mortality rate was 22%. Conclusions: CDI is an emerging HAI in India. All hospitals need to set up policies for surveillance, testing, treatment and prevention of CDI based on recent international guidelines and local infrastructure/logistics.

Glutamato deshidrogenasa: Su valor diagnóstico en la diarrea por Clostridioides difficile / Glutamate dehydrogenase: Its diagnostic value in Clostridioides difficile diarrhea

Clostridioides difficile es el principal agente causal de diarreas asociadas al cuidado de la salud. Esta bacteria produce toxinas y una enzima que se encuentra muy conservada en la especie: la glutamato deshidrogenasa (GDH). El diagnóstico rápido y el tratamiento efectivo permiten la pronta mejoría del paciente, con el consecuente control de la diseminación del microorganismo. Sin embargo, aún no se cuenta con un método diagnóstico óptimo y se propone la realización de diversas pruebas, cuyos resultados se interpretan en el contexto de ciertos algoritmos. En este trabajo se evaluó el desempeño de la GDH como prueba de tamizaje en el diagnóstico de la diarrea por c. difficile. Se estudiaron 615 muestras de materia fecal. Se determinó la presencia de GDH y de toxinas mediante el equipo diagnóstico de enzimoinmunoensayo de membrana C. DIFF QUIK-CHEK COMPLETE® (TECHLAB) y se realizaron cultivos para la búsqueda de C. difficile. Se calcularon los valores de sensibilidad, especificidad, VPP y VPN con un nivel de significación p < 0,05. Se detectó GDH en 266 muestras (43,25%), con una sensibilidad del 100% y una especificidad del 87,10%, IC95: 84,58-91,42. Se hallaron toxinas en 218 muestras (35,45%) y C. difficile desarrolló en 235 cultivos (38,21%). De 48 muestras GDH positivas y sin producción de toxina/s, 17 fueron positivas al cultivo de C. difficile, con 15 aislamientos toxigénicos y 2 no toxigénicos. No hubo desarrollo de C. difficile en las 31 muestras restantes. Ninguna muestra GDH negativa dio resultado positivo de toxina/s ni desarrollo en el cultivo, por lo cual el VPN de la GDH fue del 100%, mientras que el VPP fue del 81,9%. Concluimos que la determinación de GDH representa un screening adecuado para descartar casos de diarrea por C. difficile, por lo tanto de valor en los algoritmos diagnósticos de las diarreas infecciosas.

Clostridioides difficile is the main etiological agent of diarrhea associated with health care, it produces toxins and glutamate dehydrogenase (GDH), an enzyme that is highly conserved in this species. Rapid diagnosis and effective treatment produce prompt improvement of the patient and subsequent control of the microorganism spread. There are several techniques whose results are interpreted in the context of algorithms. However, the optimal diagnostic method is yet unknown. The performance of GDH as a screening test for the diagnosis of C. difficile diarrhea was assessed. Six hundred and fifteen stool samples were studied. The presence of GDH and toxins presence was determined by TECHLAB® C. DIFF QUIK-CHEK COMPLETE and the samples were cultured for the search of C. difficile. The values of sensitivity, specificity, PPV and NPV were calculated with a p value of 0.05 or less. GDH was detected in 266 samples (43.25%), with a sensitivity of 100% and specificity of 87.10%, IC95: 84.58-91.42; toxin/s were detected in 218 (35.45%) and C. difficile developed in 235 cultures (38.21%). From 48 samples with positive GDH and negative toxin/s, 15 toxigenic and 2 non-toxigenic isolates were obtained, the remaining 31 samples were negative for C. difficile. All GDH-negative samples were negative for toxins or culture, therefore, GDH NPV was 100%, while PPV was 81.9%. We conclude that GDH is a suitable screening test for the diagnostic algorithm of C. difficile diarrhea.

Characterization of glutamate dehydrogenase SHJG 7666 from Streptomyces hygroscopicus 5008 / 中国药科大学学报

Glutamate dehydrogenase (GDH)a key enzyme in the nitrogen metabolism pathway catalyzes the con-version between α-ketoglutarate and glutamate reversibly using NAD(P)H as a cofactor. Based on genomic stud-ies,it was concluded that SHJG_7666 was a potential GDH in Streptomyces hygroscopicus 5008(S5008),and its expression level in vivo was positively correlated with the biosynthesis of an important aminocyclol compound vali-damycin. Phylogenetic tree analysis showed that the S5008 SHJG_7666 GDH belonged to the Glu/Leu/Phe/Val dehydrogenase family,with conserved glutamate-α-ketoglutarate binding domain and the classical GXGXXG dinu-cleotide binding motif. Further homologous modeling and structural comparison revealed that SHJG_7666 con-tained conserved Lys60,Lys78and Asp120catalytic functional sites and ligand binding residues Ser36,Gly38,Gln119 and Asp166,Asn300,Ala330. Moreover,recombinant expression of SHJG_7666 in E. coli and in vitro enzyme activity demonstrated that glutamate dehydrogenase can convert ammonium salt to glutamate with pH and temperature being optimal at 7. 5 and 37 °C respectively. Enzyme activity under optimum reaction condition has Kmvalue of (25. 3 ±9. 1)μmol/L and kcatof (3 ±0. 8)×10 -5s-1for the substrate α-ketoglutarate. Results of this study further improved the catalytic activity of SHJG_7666,thus laying the foundation for the ultimate increase of vali-damycin production.

A thermophilic microorganism from Deception Island, Antarctica with a thermostable glutamate dehydrogenase activity

BACKGROUND: The Antarctic continent is a source of extreme microorganisms. Millions of years of isolation have produced unique biodiversity with adaptive responses to its extreme environment. Although the Antarctic climate is mainly cold, the presence of several geothermal sites, including thermal springs, fumaroles, hot soils and hydrothermal vents, provides ideal environments for the development of thermophilic and hyperthermophilic microorganisms. Their enzymes, called thermoenzymes, are the focus of interest in both academic and industrial research, mainly due to their high thermal activity and stability. Glutamate dehydrogenase, is an enzyme that plays a key role in the metabolism of carbon and nitrogen catalyzing reversibly the oxidative deamination of glutamate to alpha-ketoglutarate and ammonium. It belongs to the family of oxidoreductases, is widely distributed and it has been highly regarded for use as biosensors, particularly for their specificity and ability to operate in photochemical and electrochemical systems. However, the use of enzymes as biosensors is relatively problematic due to their instability to high temperatures, organic solvents and denaturing agents. The purpose of this study is to present the partial characterization of a thermophilic microorganism isolated from Deception Island, Antarctica, that displays glutamate dehydrogenase activity. RESULTS: In this work, we report the isolation of a thermophilic microorganism called PID15 from samples of Deception Island collected during the Antarctic Scientific Expedition ECA 46. This microorganism is a thermophile that grows optimally at 50 °C and pH 8.0. Scanning electron microscopy shows rod cells of 2.0 to 8.0 µm of length. Phylogenetic analysis of 16S rRNA gene revealed that this microorganism is closely related to Bacillus gelatini. This microorganism contains a thermostable glutamate dehydrogenase with optimal activity at pH 8.0 and temperatures for its activity from 37 to 50 °C, range of temperature of interest for biotechnological applications. This glutamate dehydrogenase is a highly thermostable enzyme. CONCLUSION: This is the first report of a microorganism from Antarctica containing a thermostable glutamate dehydrogenase that maintains its activity in a broad range of temperatures making it of potential interest for biotechnological applications.

High Throughput Screening Method and Application for L-glutamate Specific Aminotransferase / 中国生物工程杂志

Objective:The aim is to establish L-glutamate specific aminotransferase-L-glutamate dehydrogenase coupling 96-well high throughput screening method,which is applied to molecular evolution of aminotransferase WecE from E.coli.Methods:An optical assay for aminotransferase catalytic activity based on aminotransferase-glutamate dehydrogenase coupling system is established by optimization of coupling enzyme loading,signal molecule NADH concentration and coupling time.Mutants library of WecE is obtained by sitedirected saturation mutagenesis.Positive mutants can be screened out through 96-well preliminary screening and flask second screening.Results:The target transamination reaction is coupled with L-glutamate dehydrogenase indicative reaction system which consists of 0.5 U/ml enzyme loading and 0.4 mmol/L NADH.A positive mutant Y321F whose catalytic activity increases 3.4 fold compared to that of wild type is screened out in Tyr 321 saturation mutagenesis library of WecE.Conclusion:An accurate high throughput screening method with weak background interference is established.It offers feasible solution for molecular evolution of L-glutamate specific aminotransferase.

Aminotransferase and glutamate dehydrogenase activities in lactobacilli and streptococci

ABSTRACT Aminotransferases and glutamate dehydrogenase are two main types of enzymes involved in the initial steps of amino acid catabolism, which plays a key role in the cheese flavor development. In the present work, glutamate dehydrogenase and aminotransferase activities were screened in twenty one strains of lactic acid bacteria of dairy interest, either cheese-isolated or commercial starters, including fifteen mesophilic lactobacilli, four thermophilic lactobacilli, and two streptococci. The strains of Streptococcus thermophilus showed the highest glutamate dehydrogenase activity, which was significantly elevated compared with the lactobacilli. Aspartate aminotransferase prevailed in most strains tested, while the levels and specificity of other aminotransferases were highly strain- and species-dependent. The knowledge of enzymatic profiles of these starter and cheese-isolated cultures is helpful in proposing appropriate combinations of strains for improved or increased cheese flavor.

Expression and antigenicity analysis of Clostridium difficile glutamate dehydrogenase / 军事医学

Objective To construct prokaryotic expression vectors for glutamate dehydrogenase(GDH)of Clostridium difficile(CD),and express recombinant GDH in Escherichia coli,and identify its antigenicityed.Methods The entire gene of GDH was cloned from ATCC43255 genome DNA.The recombinant antigens were expressed in E.coli with IPTG induction and purified by Ni-NATBeads.The antigenicity was detected using CD Qick Chek Complete dual-antigen EIA. Results Prokaryotic expression vectors of CD GDH were constructed successfully.The antigen could be identified by specific anti-GDH antibodies.Conclusion The GDH antigen can be used to prepare corresponding antibodies,which facilitate the development of immunoassay for CD GDH.

Genotipos de Giardia duodenalis en muestras de niños de las guarderías del Instituto Colombiano de Bienestar Familiar y de perros en Ibagué, Colombia / Giardia duodenalis genotypes found in the Instituto Colombiano de Bienestar Familiar day care centers and dogs in Ibagué, Colombia

Introducción. Se han descrito ocho genotipos de Giardia duodenalis, del A al H. Los genotipos A y B se han aislado de humanos y de una gran variedad de mamíferos; sin embargo, los genotipos del C al H han mostrado mayor especificidad de huésped. Objetivo. Identificar los genotipos de G. duodenalis a partir de quistes obtenidos en heces de niños de las guarderías del Instituto Colombiano de Bienestar Familiar (ICBF) y de perros en Ibagué, mediante PCR-RFLP de los genes de la beta giardina y la glutamato deshidrogenasa. Materiales y métodos. Los quistes de las muestras positivas para G. duodenalis fueron sometidos a concentración; se extrajo su ADN y se efectuó el análisis de PCR-RFLP de los genes de la beta giardina y de la glutamato deshidrogenasa. Como control positivo se utilizó la cepa MHOM/CO/04/G40 procedente del Grupo de Parasitología del Instituto Nacional de Salud. Resultados. De las muestras tomadas de niños, 11/23 (48 %) correspondieron al genotipo A y, 12/23 (52 %), al genotipo B. Cuatro muestras de perros presentaron los genotipos C y D, específicos de este huésped. Conclusiones. En los niños solamente se encontraron los genotipos asociados a infecciones humanas (AII, BIII y BIV) y en los perros, los genotipos específicos para este huésped (C y D). Debido al reducido tamaño de las muestras analizadas provenientes de perros, y dado que estos no estuvieron en contacto con los niños de las guarderías del ICBF, no fue posible determinar una interacción entre el ciclo de transmisión de los humanos y el de los animales.

Introduction: Eight Giardia duodenalis genotypes (A-H) have been described to date. Genotypes A and B have been isolated from humans and a wide range of mammals; however, genotypes C-H have shown greater host specificity. Objective: Identifying G. duodenalis genotypes from cysts in faeces obtained from children attending the Instituto Colombiano de Bienestar Familiar (ICBF) day care centres and from dogs in Ibagué by PCR-RFLP targeting both the b -giardin and glutamate dehydrogenase genes. Materials and methods: Cysts from G. duodenalis positive samples were concentrated, DNA was extracted and the b -giardin and glutamate dehydrogenase genes were analysed by PCR-RFLP. The MHOM/CO/04/G40 strain was used as positive control (this was obtained from the Grupo de Parasitología at the Instituto Nacional de Salud ). Results: Of the total human samples, 11/23 (48%) were genotyped as A and 12/23 (52%) as B; PCR-RFLP revealed that four canine samples were genotypes C and D, these being host-specific. Conclusions: Only genotypes associated with human infection (AII, BIII and BIV) were found in the children and host-specific genotypes were observed in canines (C and D). No interaction could be established between animal and human transmission cycles due to the small canine sample size and as the former did not come into contact with children attending ICBF day-care centres.

Biochemical studies in relation to glutamate dehydrogenase in piper nigrum (L.).

Black pepper, the king of spices, the most important and widely used spice in the world is the dried mature berries of P. nigrum L. Inorganic nitrogen is assimilated into amino acids glutamine, glutamate, asparagines and aspartate which serve as important nitrogen carriers in plants. The enzymes glutamine synthetase (GS) EC. 6.3.1.2, glutamate synthase (GOGAT) E.C. 1.4.1.14, glutamate dehydrogenase (GDH) E.C.1.4.1.4, aspartate aminotransferase and asparagine synthetase are responsible for biosynthesis of these amino acids. Although extensive studies have been carried out on the epidemiology of the diseases and agronomical aspects of P. nigrum, very few studies have been made on the enzymological aspects especially that associated with the nitrogen assimilation. A better understanding of the various properties of the enzyme will be valuable in the future studies concerned with Nitrogen metabolism in P. nigrum. Main objective of present study was to standardize the extraction and study the properties of GDH from P. nigrum L. Effect of additives and its optimum concentration were determined, standardized homogenizing medium was formulated, standardized assay system formulated, different properties like pH optimum, Substrate saturation and km value determined; it’s all in agreement with the previously reported values, result indicate NADP+/NADPH is the better substrate i.e. the enzyme activity is contributed by chloroplastic form of GDH than by the mitochondrial form.

Turn-on Fluorescent Probe Based on Quantum Dots for Detection of Trace Amount Glutamate Dehydrogenase / 分析化学

We reported a simple and fast fluorescence system based on quantum dots ( QDs ) to detect glutamate dehydrogenase ( GLDH) , which inverted glutamate to α-ketogrutarate using NAD+ as a coenzyme. The fluorescence of CdTe QDs was quenched by nicotinamide adenine dimucleotide ( NAD+) through an electron transfer pathway, and the quencher NAD+ could be consumed by adding NAD+-dependent enzymes and corresponding substrates. Based on this principle we introduced GLDH to consume NAD+ in the QDs/NAD+ system, leading to the enhancement of the fluorescence intensity of QDs, which was in proportional to the amounts of GLDH added. Using this fluorescence system, we measured GLDH in a wide concentration range from 10 U/L to 1000 U/L, which was of significance in clinical diagnosis of different kinds of liver diseases.

Neonatal hyperinsulinism/hyperammonemia syndrome / 中国小儿急救医学

Neonatal hyperinsulinism/hyperammonemia syndrome is a genetic disease result from glutamate dehydrogenase gene mutations.The clinical manifestations are hypoglycemia,hyperinsulinemia and mild hyperammonemia.Hypoglycemia may occur quickly due to eating protein.It is a rare neonatal disease that was easily ignored or delayed diagnosis and treatment causing serious sequelae of nervous system.This review summarized pathogenesis,clinical manifestation and diagnosis of the disease.

Evaluation of a Rapid Membrane Enzyme Immunoassay for the Simultaneous Detection of Glutamate Dehydrogenase and Toxin for the Diagnosis of Clostridium difficile Infection

We evaluated the new C. DIFF QUIK CHEK COMPLETE (CD COMPLETE; TechLab, USA), which is a rapid membrane enzyme immunoassay that uses a combination of glutamate dehydrogenase (GDH) antigen and toxin A and B detection. A total of 608 consecutive loose stool specimens collected from the patients with suspected Clostridium difficile infection (CDI) from August to December 2012 were subjected to the CD COMPLETE and VIDAS Clostridium difficile A & B (VIDAS CDAB; bioMerieux, France). Their performances were compared with a toxigenic culture as a reference. Stool specimens that were culture-negative and CD COMPLETE- or VIDAS CDAB-positive were analyzed by using an enrichment procedure. In comparison to the toxigenic cultures, sensitivity, specificity, positive predictive values (PPV), and negative predictive values (NPV) were 63.6%, 98.0%, 76.1%, and 96.4%, respectively, for the CD COMPLETE-toxin and 75.5%, 97.4%, 72.5%, and 97.8%, respectively, for the VIDAS CDAB. In comparison to the enriched C. difficile cultures, the sensitivity, specificity, PPV, and NPV for the CD COMPLETE-GDH were 91.0%, 92.4%, 70.5%, and 98.1%, respectively. The CD COMPLETE is a reliable method for the diagnosis of CDI and provides greater sensitivity than toxin enzyme immunoassay alone. Furthermore, the CD COMPLETE-GDH has advantages over direct culture in detecting C. difficile.

Molecular identification of Giardia duodenalis in Ecuador by polymerase chain reaction-restriction fragment length polymorphism

The aim of this study was to determine the genetic diversity of Giardia duodenalis present in a human population living in a northern Ecuadorian rain forest. All Giardia positive samples (based on an ELISA assay) were analysed using a semi-nested polymerase chain reaction-restriction fragment length polymorphism assay that targets the glutamate dehydrogenase (gdh) gene; those amplified were subsequently genotyped using NlaIV and RsaI enzymes. The gdh gene was successfully amplified in 74 of 154 ELISA positive samples; 69 of the 74 samples were subsequently genotyped. Of these 69 samples, 42 (61%) were classified as assemblage B (26 as BIII and 16 as BIV), 22 (32%) as assemblage A (3 as AI and 19 as AII) and five (7%) as mixed AII and BIII types. In this study site we observe similar diversity in genotypes to other regions in Latin America, though in contrast to some previous studies, we found similar levels of diarrheal symptoms in those individuals infected with assemblage B compared with those infected with assemblage A.

Prevalencia de Giardia intestinalis y predominio de genotipos zoonóticos en ovinos y bovinos de traspatio de cinco estados de la República Mexicana / Prevalence of Giardia intestinalis and zoonotic genotype predominance in small scale sheep and cattle farms in five states of the Mexican Republic

The aim of this paper was to discover the prevalence and assemblages of Giardia intestinalis, harbored in sheep and cows on familiar farms from five states of the Mexican Republic. Stool samples from 265 sheep and 174 cows were analyzed by centrifugation and flotation in zinc sulfate to search for cysts and ova. The samples with Giardia cysts were processed in a Sheather solution in order to isolate them. Afterwards, cultures were established in TYI-S-33, each one of which was the Giardia DNA source. The DNA was obtained and used as a template to amplify a fragment of the glutamate dehydrogenase (gdh) enzyme. The 430 bp amplicons were restricted with Nla IV and Rsa I in order to identify the restriction fragments length polymorphisms (RFLP's) patterns. From the cyst analysis, Giardia cysts in nine cows (5.1%) and 30 sheep (11.3%) were found. Then 10 axenic cultures (5 from sheep and 5 from cows) were set up. From the RFLP's pattern it was found that one cow had assemblage (AI), another two had a mixture of assemblages (AI + BIII) and the other two had (E + BIII). In sheep, it was found that two sheep had assemblage (AI) and the other three had a mixture of assemblages (AI + BIII). This is the first report in which zoonotic assemblages (A-I and BIII) predominance in ruminants from five states of Mexico have been demonstrated. Therefore, it is necessary to carry out further studies aimed at discovering other Giardia genotypes and transmission patterns between animals and humans in Mexico.

Con el fin de determinar la frecuencia y genotipos de Giardia intestinalis en ovinos y bovinos de traspatio de algunos estados de la República Mexicana, en este trabajo se colectaron heces de 265 ovinos y 174 bovinos, para la búsqueda de Giardia mediante coproparasitoscópicos (CPS) de concentración flotación. De las muestras fecales que resultaron positivas se obtuvieron los quistes por el método de Sheather. Los quistes se desenquistaron in vitro y los trofozoítos se mantuvieron en cultivo TYI-S-33 axénico. El ADN de los trofozoítos se obtuvo mediante extracciones fenólicas y se amplificó un segmento de ≈ 430 pb del gen de la enzima glutamato deshidrogenasa (gdh) por medio de la reacción en cadena de la ADN polimerasa (PCR), el producto se restringió con las enzimas Nla IV y Rsa I y se obtuvieron los polimorfismos de los fragmentos de restricción (RFLP). En los CPS se encontró a Giardia en nueve bovinos (5.1%) y 30 ovinos (11.3%). Se establecieron 10 cultivos axénicos (5 de bovinos y 5 de ovinos). En un bovino se encontró el genotipo (AI), dos tuvieron mezcla de los genotipos (AI + BIII) y los otros dos fueron (E + BIII). Un ovino fue genotipo (AI) y tres tuvieron mezcla de los genotipos (AI + BIII). Éste es el primer informe que presenta predominio de genotipos zoonóticos (AI y BIII) en ovinos y bovinos de México. Es necesario investigar los genotipos de Giardia y patrones de transmisión entre animales y humanos en México.

Comparison between the two-step and the three-step algorithms for the detection of toxigenic Clostridium difficile.

Purpose: To evaluate usefulness of applying either the two-step algorithm (Ag-EIAs and CCNA) or the three-step algorithm (all three assays) for better confirmation of toxigenic Clostridium difficile. The antigen enzyme immunoassays (Ag-EIAs) can accurately identify the glutamate dehydrogenase antigen of toxigenic and nontoxigenic Clostridium difficile. Therefore, it is used in combination with a toxin-detecting assay [cell line culture neutralization assay (CCNA), or the enzyme immunoassays for toxins A and B (TOX-A/BII EIA)] to provide specific evidence of Clostridium difficile-associated diarrhoea. Materials and Methods: A total of 151 nonformed stool specimens were tested by Ag-EIAs, TOX-A/BII EIA, and CCNA. All tests were performed according to the manufacturer's instructions and the results of Ag-EIAs and TOX-A/BII EIA were read using a spectrophotometer at a wavelength of 450 nm. Results: A total of 61 (40.7%), 38 (25.3%), and 52 (34.7%) specimens tested positive with Ag-EIA, TOX-A/BII EIA, and CCNA, respectively. Overall, the sensitivity, specificity, negative predictive value, and positive predictive value for Ag-EIA were 94%, 87%, 96.6%, and 80.3%, respectively. Whereas for TOX-A/BII EIA, the sensitivity, specificity, negative predictive value, and positive predictive value were 73.1%, 100%, 87.5%, and 100%, respectively. With the two-step algorithm, all 61 Ag-EIAs-positive cases required 2 days for confirmation. With the three-step algorithm, 37 (60.7%) cases were reported immediately, and the remaining 24 (39.3%) required further testing by CCNA. By applying the two-step algorithm, the workload and cost could be reduced by 28.2% compared with the three-step algorithm. Conclusions: The two-step algorithm is the most practical for accurately detecting toxigenic Clostridium difficile, but it is time-consuming.