Experimental Study of the Mechanical Transmission of Rabbit Hemorrhagic Disease Virus (RHDV2/b) by Aedes albopictus (Diptera: Culicidae) and Phlebotomus papatasi (Diptera: Psychodidae)

Rabbit hemorrhagic disease (RHD) is caused by a lagovirus mainly affecting European rabbits (Oryctolagus cuniculus), although other European and North American lagomorph species are also susceptible to fatal infection by the new viral variant RHDV2/b. In the present work, direct mechanical transmission of the rabbit hemorrhagic disease virus (RHDV2/b variant) by the hematophagous Diptera Aedes albopictus (Skuse) (Diptera: Culicidae) and the sand fly Phlebotomus papatasi (Scopoli) (Diptera: Psychodidae) was tested. For each species, six and three laboratory rabbits were exposed to bites of dipterous females partially fed on RHDV2/b viral suspension 2 h and 24 h prior to exposure, respectively. The rabbits were then monitored for clinical changes and mortality for 35 d, and seroconversion was assessed by indirect ELISA. No rabbit died or showed clinical signs of disease, and seroconversion was recorded in two rabbits challenged with P. papatasi females fed the viral suspension 2 h prior to exposure. The number of RHDV2/b RNA copies/female was higher in Ae. albopictus than in P. papatasi but the decrease over time of RNA load in Ae. albopictus was greater than that in P. papatasi. The results of this study suggest the inability of Ae. albopictus to serve as a direct mechanical vector of RHDV2/b, but sand flies could play a role in the local transmission of RHD.

Agreement among equine veterinarians and between equine veterinarians and inertial sensor system during clinical examination of hindlimb lameness in horses

BACKGROUND

Hindlimb lameness evaluation is known to be challenging. Experience is essential for the ability of equine veterinarians to detect lameness. Nevertheless, even an experienced veterinarian is still subject to bias. Objective lameness detecting methods have been established to aid veterinarians.

OBJECTIVES

1) To estimate the effect of experience on the interobserver agreement and the agreement between a body-mounted inertial sensor system (BMISS) and veterinarians on detecting hindlimb lameness, and 2) to estimate the agreement between the BMISS and highly experienced veterinarians on change in lameness after diagnostic analgesia.

STUDY DESIGN

Cross-sectional study.

METHODS

Twenty-six horses with hindlimb lameness were evaluated in clinical conditions by clinicians and simultaneously measured by the BMISS. Videos of their lameness examination were recorded and shown to 13 veterinarians from three groups of varying experience for evaluation. The interobserver agreement and the agreement between veterinarians and the BMISS were calculated.

RESULTS

Interobserver agreement from all three groups was recorded as 'fair'. The strength of agreement between veterinarians and BMISS was 'fair' for the highly experienced group, 'slight to fair' for the moderately experienced group and 'slight' in the inexperienced group. The BMISS and the highly experienced veterinarians declared a 'strong' agreement in assigning an improvement in lameness after diagnostic analgesia.

MAIN LIMITATIONS

Lameness evaluation through video viewing might be more challenging for some evaluators than live situations.

CONCLUSIONS

Given the task of evaluating videos of horses trotting in a straight line, the more experienced veterinarians did not show more reliability than those with less experience. Due to 1) the moderate agreement between the BMISS and clinicians (highly experienced and moderately experienced) in the live clinical evaluation in determining hindlimb lameness, and 2) the strong association between the BMISS and highly experienced veterinarians in determining improvement of lameness after anaesthesia, therefore the use of the BMISS as a supporting tool for veterinarians is encouraged.

Co-activation of STAT3 and YES-Associated Protein 1 (YAP1) Pathway in EGFR-Mutant NSCLC

Background

The efficacy of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) in EGFR-mutant non-small cell lung cancer (NSCLC) is limited by adaptive activation of cell survival signals. We hypothesized that both signal transducer and activator of transcription 3 (STAT3) and Src-YES-associated protein 1 (YAP1) signaling are dually activated during EGFR TKI treatment to limit therapeutic response.

Methods

We used MTT and clonogenic assays, immunoblotting, and quantitative polymerase chain reaction to evaluate the efficacy of EGFR TKI alone and in combination with STAT3 and Src inhibition in three EGFR-mutant NSCLC cell lines. The Chou-Talalay method was used for the quantitative determination of drug interaction. We examined tumor growth inhibition in one EGFR-mutant NSCLC xenograft model (n = 4 mice per group). STAT3 and YAP1 expression was evaluated in tumors from 119 EGFR-mutant NSCLC patients (64 in an initial cohort and 55 in a validation cohort) by quantitative polymerase chain reaction. Kaplan-Meier and Cox regression analyses were used to assess the correlation between survival and gene expression. All statistical tests were two-sided.

Results

We discovered that lung cancer cells survive initial EGFR inhibitor treatment through activation of not only STAT3 but also Src-YAP1 signaling. Cotargeting EGFR, STAT3, and Src was synergistic in two EGFR-mutant NSCLC cell lines with a combination index of 0.59 (95% confidence interval [CI] = 0.54 to 0.63) for the PC-9 and 0.59 (95% CI = 0.54 to 0.63) for the H1975 cell line. High expression of STAT3 or YAP1 predicted worse progression-free survival (hazard ratio [HR] = 3.02, 95% CI = 1.54 to 5.93, P = .001, and HR = 2.57, 95% CI = 1.30 to 5.09, P = .007, respectively) in an initial cohort of 64 EGFR-mutant NSCLC patients treated with firstline EGFR TKIs. Similar results were observed in a validation cohort.

Conclusions

Our study uncovers a coordinated signaling network centered on both STAT3 and Src-YAP signaling that limits targeted therapy response in lung cancer and identifies an unforeseen rational upfront polytherapy strategy to minimize residual disease and enhance clinical outcomes.

Abstract 265: Cotargeting EGFR, STAT3 and Src-Notch pathways: a promising approach to improve the efficacy of EGFR-TKIs in the treatment of NSCLC patients

Intrinsic or acquired resistance limits the clinical effectiveness of EGFR tyrosine kinase inhibitors (TKIs) for non-small cell lung cancer (NSCLC) patients (p) with EGFR mutations. One of the signaling mediators downstream of activated EGFR is signal transducer and activator of transcription 3 (STAT3). Not only does gefitinib not inhibit STAT3, but it also augments STAT3 tyrosine phosphorylation. EGFR blockade enriches lung cancer stem cells (CSCs) through NOTCH3-dependent signaling. A co-receptor of IL-6 (gp130) associates with Src and triggers activation of YAP and NOTCH. Our study is designed with three parallel objectives: firstly, to demonstrate that single EGFR TKI treatment cannot abrogate STAT3 and Src in EGFR mutant NSCLC cell lines; secondly, to examine whether the combination of gefitinib with compounds that target STAT3, (TPCA-1) and Src (saracatinib), suppresses the mechanisms of resistance; thirdly, to identify biomarkers in clinical tumor samples that may help us predict the outcome of EGFR TKIs and design effective combination therapies. Cell viability assay (MTT), western blotting, quantitative-real time PCR (qRT-PCR) and aldefluor assay-flow cytometry were used. We found that gefitinib increases pSTAT3 Y705 in PC-9 cells (that harbor the exon 19 deletion) in a time- and dose-dependent manner. Nine days after gefitinib treatment STAT3 mRNA level was significantly elevated. PC-9 cells showed dramatic increase in the fraction of ALDH+ cells upon treatment with gefitinib. TPCA-1 increased sensitivity to gefitinib in the PC-9 cells. Combination of gefitinib with TPCA-1 abrogated pSTAT3 Y705 but neither inhibited pPaxillin Y118 (Src induced) and pYAP S127 nor prevented the increment in the ALDH+ CSCs subpopulation. The triple combination of gefitinib, TPCA-1 and saracatinib was highly synergistic and abrogated pSTAT3 Y705, pPaxillin Y118 and pYAP S127. We performed qRT-PCR at baseline tumor samples of 64 EGFR mutant NSCLC p treated with first line EGFR TKIs and found that high expression of STAT3 and YAP were significantly correlated with shorter median progression-free survival (mPFS). mPFS was 9.6 months (m) (95% CI, 5.9 to 14.1) for p with low STAT3 and 18.4m (95% CI, 8.8 to 30.2) for p with high STAT3 mRNA expression (P<0.001). mPFS was 9.6 months (95% CI, 7.7 to 15.2) for p with low YAP and 23.4 months (95% CI, 13.0 to 28.1) for p with high YAP mRNA expression (P = 0.005). A combined STAT3 and YAP risk group model was constructed since the mRNA expression of the 2 transcripts was weakly correlated (r = .0.15; P = 0.305). mPFS was 25.7 months for p with low STAT3 and YAP mRNA (95% CI, 8.5 to 60.9), 9.4 months for p with high STAT3 and YAP mRNA (95% CI, 2.8 to 15.2), and 14.1 months for others (95% CI, 8.2 to 23.4) (P = 0.004). Single EGFR TKI treatment can no longer be considered adequate for p with EGFR mutant lung cancer and a clinical trial co-targeting STAT3 and Src is warranted.

Citation Format: Niki Karachaliou, Imane Chaib, Sara Pilotto, Jordi Codony, Xueting Cai, Xuefei Li, Ana Drozdowskyj, Carles Codony, Andrés Felipe Cardona, Guillermo López-Vivanco, Alain Vergnenègre, José Miguel Sánchez, Mariano Provencio, Filippo de Marinis, Enric Carcereny, Noemí Reguart, Rosario García-Campelo, Silvia Marin, Cristina Teixido, Isabella Sperduti, Sonia Rodríguez, Roger Estrada, Raimon Puig de la Bellacasa, José Luis Ramírez, Miguel Angel Molina-Vila, Caicun Zhou, Peng Cao, Patrick Ma, Trever Bivona, Rafael Rosell. Cotargeting EGFR, STAT3 and Src-Notch pathways: a promising approach to improve the efficacy of EGFR-TKIs in the treatment of NSCLC patients. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 265.

PCR Conditions for 16S Primers for Analysis of Microbes in the Colon of Rats

The study of the composition of the intestinal flora is important to the health of the host, playing a key role in maintaining intestinal homeostasis and the evolution of the immune system. For these studies, various universal primers of the 16S rDNA gene are used in microbial taxonomy. Here, we report an evaluation of 5 universal primers to explore the presence of microbial DNA in colon biopsies preserved in RNAlater solution. The DNA extracted was used for the amplification of PCR products containing the variable (V) regions of the microbial 16S rDNA gene. The PCR products were studied by restriction fragment length polymorphism (RFLP) analysis and DNA sequence, whose percent of homology with microbial sequences reported in GenBank was verified using bioinformatics tools. The presence of microbes in the colon of rats was quantified by the quantitative PCR (qPCR) technique. We obtained microbial DNA from rat, useful for PCR analysis with the universal primers for the bacteria 16S rDNA. The sequences of PCR products obtained from a colon biopsy of the animal showed homology with the classes bacilli (Lactobacillus spp) and proteobacteria, normally represented in the colon of rats. The proposed methodology allowed the attainment of DNA of bacteria with the quality and integrity for use in qPCR, sequencing, and PCR-RFLP analysis. The selected universal primers provided knowledge of the abundance of microorganisms and the formation of a preliminary test of bacterial diversity in rat colon biopsies.

Design, synthesis and biological evaluation of pyrido[2,3-d]pyrimidin-7-(8H)-ones as HCV inhibitors

The design and selection of a combinatorial library of pyrido[2,3-d]pyrimidin-7(8H)-ones (4) has allowed the synthesis of 121 compounds, using known and new synthetic methodologies, and the evaluation of the inhibitory activity against hepatitis C virus (HCV) genotype 1b replicon. Among these compounds, 21{4,10} and 24{2,10} presented very high activities [EC50 = 0.027 μM (CC50 = 5.3 μM) and EC50 = 0.034 μM (CC50 = 13.5 μM), respectively] and high selectivity indexes, 196 and 397. These values are similar to the EC50 reported for sofosbuvir (2) (0.048 μM) using a similar methodological approach and the same virus subtype. 21{4,10} and 24{2,10} are obtained through shorter synthetic itineraries than sofosbuvir and 24{2,10} is achiral contrary to sofosbuvir which presents 4 stereogenic centers. In silico studies suggest that 21{4,10} and 24{2,10} inhibits NS5B polymerase through allosteric site binding.

Abundance modelling of invasive and indigenous Culicoides species in Spain

In this paper we present a novel methodology applied in Spain to model spatial abundance patterns of potential vectors of disease at a medium spatial resolution of 5 x 5 km using a countrywide database with abundance data for five Culicoides species, random regression Forest modelling and a spatial dataset of ground measured and remotely sensed eco-climatic and environmental predictor variables. First the probability of occurrence was computed. In a second step a direct regression between the probability of occurrence and trap abundance was established to verify the linearity of the relationship. Finally the probability of occurrence was used in combination with the set of predictor variables to model abundance. In each case the variable importance of the predictors was used to biologically interpret results and to compare both model outputs, and model performance was assessed using four different accuracy measures. Results are shown for C. imicola, C. newsteadii, C. pulicaris group, C. punctatus and C. obsoletus group. In each case the probability of occurrence is a good predictor of abundance at the used spatial resolution of 5 x 5 km. In addition, the C. imicola and C. obsoletus group are highly driven by summer rainfall. The spatial pattern is inverse between the two species, indicating that the lower and upper thresholds are different. C. pulicaris group is mainly driven by temperature. The patterns for C. newsteadii and C. punctatus are less clear. It is concluded that the proposed methodology can be used as an input to transmission-infection-recovery (TIR) models and R0 models. The methodology will become available to the general public as part of the VECMAP™ software.

Survey of flea infestation in cats in Spain

Fleas are a common cause of feline skin disorders as well as vectors of zoonotic diseases. This study evaluated the flea species infesting domestic cats in Spain and assessed factors influencing their distribution. Fleas from 217 cats from 57 localities in Spain were identified and associations between abundance, and host-dependent, host habitat and environmental factors were examined. Variations in infracommunity and component community structure were also explored. Three species were present, of which Ctenocephalides felis (Bouché) (Siphonaptera: Pulicidae) was the most abundant (98.4%), followed by Ctenocephalides canis (Curtis) (1.1%) and Pulex irritans (L.) (Siphonaptera: Pulicidae) (0.5%). Overall abundance and abundances of both C. felis and C. canis were higher on farms than in apartments, but overall flea abundance and abundances of both C. felis and C. canis were lower in rural than urban environments. Overall abundance and C. felis abundance were lower during the warmest months, and mean annual rainfall was positively correlated with overall, C. felis and C. canis abundances. No relationship between the number of species per cat and any host, habitat or physiographical variable was found. Species richness was not correlated with mean annual temperature or rainfall. Flea abundance was mainly associated with host habitat and environmental factors.

Host feeding patterns of Culicoides species (Diptera: Ceratopogonidae) within the Picos de Europa National Park in northern Spain

Blood meal identification can provide information about the natural host-feeding patterns or preferences of Culicoides species. Such information could indirectly provide data indicating which reservoirs are significant in associated vector-borne diseases. We positively identified the host species through DNA sequencing of the cytochrome b gene in 144 of the 170 (84.7%) blood meal specimens tested. In the remaining samples, identification of the blood-meal source was unsuccessful, possibly due to the post-ingestion time prior to sampling or the availability of the species-specific cytochrome b gene sequences in the database. The majority of identified blood meals were derived from mammalian blood (95.8%), and only six contained chicken blood. We identified five species as mammalian hosts for Culicoides spp.: sheep (87.7%), human (6.5%), cattle (3.7%) and Savi's Pine Vole (Micrototus savii) (2.1%). The results suggested that large mammals, specifically ruminants, were most frequently fed upon by biting midges (Culicoides spp.), but evidence of opportunistic feeding behaviour was also found. Host feeding behaviour of Culicoides species may also be influenced by the relative abundance of a particular host species in the area being studied. In this sense, Savi's Pine Vole, a wild species, was found to be a locally relevant host and a putative reservoir for viruses transmitted by species of biting midges belonging to the Culicoides genus. Finally, feeding on multiple potential host species was observed. One midge acquired blood meals from human and chicken hosts, while four other midges fed on two different sheep.

The proximal aspect of the suspensory ligament in the horse: How precise are ultrasonographic measurements?

REASONS FOR PERFORMING STUDY

To evaluate intra- and interobserver variability in ultrasonographic measurements of the proximal aspect of the suspensory ligament (PSL) in the horse.

HYPOTHESIS

A minimum difference of ≥20% is required to differentiate reliably between physiological and pathological alterations related to dimensions.

MATERIALS AND METHODS

Two operators examined the PSL in all 4 limbs of 14 horses twice using different techniques and different probes with and without standoff pads. Measurements were taken from the longitudinal and transverse images. Inter- and intraoperator variability was evaluated using agreement indices (AI) and the 95% limits of agreement (LOA).

RESULTS

On the longitudinal scan the mean inter- and intraoperator AIs for dorsopalmar/-plantar thickness were both ≥0.89 and the 95% LOA were within target values for almost all intra- and interoperator comparisons. Similar mean AIs and 95% LOA were calculated for the dorsopalmar/-plantar thickness on the transverse image. For lateromedial width, cross-sectional area and circumference on the transverse scan, the mean inter- and intraoperator AIs ranged between 0.81 and 0.95 and the 95% LOA were higher than target values regardless of the imaging technique used. In general, better values for AIs and 95% LOA were achieved in the fore- compared with the hindlimb.

CONCLUSION AND CLINICAL RELEVANCE

Acceptable precision was identified within and between operators only for the dorsopalmar/-plantar thickness in longitudinal and in transverse scanning directions. For the lateromedial width, cross-sectional area and circumference, a relatively large variability was identified. This aspect has to be considered if these parameters are to be used for objective measurement of the PSL from the transverse ultrasound image.

Recovery rates of bluetongue virus serotypes 1, 2, 4 and 8 Spanish strains from orally infected Culicoides imicola in South Africa

Bluetongue (BT) is an infectious disease of ruminants that has spread northwards in Europe during the last decade. The aetiological agent of the disease is an arbovirus [bluetongue virus (BTV)] that belongs to the genus Orbivirus (family Reoviridae). The virus is transmitted by certain species of biting midge within the genus Culicoides (Diptera: Ceratopogonidae). Information on the vector status of the Culicoides species in a specific area will be essential to predict the risk for BTV incursion. Field-collected Culicoides (Avaritia) imicola Kieffer from South Africa were fed on blood containing several Spanish isolates of BTV. Despite the high virus concentrations in the bloodmeal (5.1-6.4 log(10) TCID(50) /mL of blood), virus was recovered from <1% of midges assayed after incubation. Virus concentrations >2.5 log(10) TCID(50) /midge in individual infected C. imicola suggest virus replication with possible risk for transmission to susceptible vertebrate hosts in the field for at least two of the serotypes assayed (BTV-1 and BTV-2). A third serotype (BTV-4) was very close to the estimated threshold for transmission. The relatively low to near refractory status of C. imicola compared with other vector species such as Culicoides bolitinos supports previous results, indicating that Culicoides species other than C. imicola may play a more important role in the epidemiology of BTV.

Protection of livestock against bluetongue virus vector Culicoides imicola using insecticide-treated netting in open areas

The protection of livestock against Culicoides species (Diptera: Ceratopogonidae) using physical barriers or chemically treated barriers is difficult owing to the small size of these biting midges and animal welfare concerns associated with the reduction of air flow. Culicoides imicola Kieffer is the main bluetongue virus vector in the Mediterranean basin, including the southern Iberian peninsula, where livestock is mainly housed in open pens or sheds which offer no physical protection against C. imicola. In this study we assessed the efficacy of surrounding yearling ewe pens with a canvas barrier or a cypermethrin-treated canvas barrier in reducing the entry of Culicoides spp. and C. imicola. Analyses were based on comparisons of Culicoides catches in traps in pens with and without barriers, and in traps located outside pens. Although there was no clear reduction in the abundance of Culicoides other than C. imicola in pens with either barrier, the C. imicola presence was markedly reduced by the insecticide-treated barrier compared with the untreated barrier; the latter did not reduce the abundance of this species in pens. Estimates of the protection conferred against C. imicola by the treated barrier differed depending on whether catch comparisons were based on outside traps or on traps located inside no-barrier pens. The results suggest that the use of insecticide-treated barriers may reduce contact between livestock and C. imicola in open areas or sheds. More research is necessary to assess the degree of protection as a function of barrier height, C. imicola abundance, and the size of the area to be protected.

Variations in the mitochondrial cytochrome c oxidase subunit I gene indicate northward expanding populations of Culicoides imicola in Spain

Culicoides imicola is the main vector for bluetongue (BT) and African horse sickness (AHS) viruses in the Mediterranean basin and in southern Europe. In this study, we analysed partial mitochondrial cytochrome c oxidase subunit I (COI) gene to characterize and confirm population expansion of Culicoides imicola across Spain. The data were analysed at two hierarchical levels to test the relationship between C. imicola haplotypes in Spain (n = 215 from 58 different locations) and worldwide (n = 277). We found nineteen different haplotypes within the Spanish population, including 11 new haplotypes. No matrilineal subdivision was found within the Spanish population, while western and eastern Mediterranean C. imicola populations were very structured. These findings were further supported by median networks and mismatch haplotype distributions. Median networks demonstrated that the haplotypes we observed in the western Mediterranean region were closely related with one another, creating a clear star-like phylogeny separated only by a single mutation from eastern haplotypes. The two, genetically distinct, sources of C. imicola in the Mediterranean basin, thus, were confirmed. This type of star-like population structure centred around the most frequent haplotype is best explained by rapid expansion. Furthermore, the proposed northern expansion was also supported by the statistically negative Tajima's D and Fu's Fs values, as well as predicted mismatch distributions of sudden and spatially expanding populations. Our results thus indicated that C. imicola population expansion was a rapid and recent phenomenon.

Entry of bluetongue vector Culicoides imicola into livestock premises in Spain

Culicoides imicola Kieffer is considered to be the main vector of bluetongue disease (BT) and African horse sickness (AHS) in the Mediterranean basin. It has been assumed that this midge species is exophilic and, consequently, that stabling of livestock should provide effective protection against these diseases. This study presents the results of sampling surveys for C. imicola carried out both inside and outside stables on three farms in mainland Spain. The number of C. imicola captured varied as a function of the populations sampled and trap location (inside vs. outside). The daily mean number captured inside during the sampling of each farm population was directly correlated with the daily mean number captured outside, but daily correlation of captures was not observed. By contrast with previous studies, the mean catch of C. imicola inside was consistently higher than that outside. No clear effect of stable characteristics on the degree of entry was detected. In addition, proportions of males and age-graded female groups varied among populations and with trap location. Proportionately more males and fewer engorged females were captured outside than inside, although the proportions varied among stables. These results contrast with those of previous studies, and with the assumed pronounced exophilic behaviour of C. imicola, and raise important questions about the vector activity of this species in the study area and its implications for the epidemiology of BT and/or AHS.

Ecological correlates of bluetongue virus in Spain: predicted spatial occurrence and its relationship with the observed abundance of the potential Culicoides spp. vector

Using data from bluetongue (BT) outbreaks caused by viral serotype 4 (BTV-4) in Spain during 2004-2005, a predictive model for BTV-4 occurrence in peninsular Spain was developed. An autologistic regression model was employed to estimate the relationships between BTV-4 presence and bioclimatic-related and host-availability-related variables. In addition, the observed abundances of the main potential Culicoides vectors during 2004-2005, namely Culicoides imicola, Culicoides obsoletus group, and species of the Culicoides pulicaris group, were compared between BTV-4 presence/absence areas predicted by the model. BTV-4 occurrence was mainly explained by bioclimatic variables, although a consideration of host-availability variables led to improved fit of the model. The area of BTV-4 presence predicted by the model largely resembled the core distribution area of C. imicola, and this species was the most abundant Culicoides spp. in predicted BTV-4 presence areas. The results suggest that the spatial expansion of BTV-4 took place only as far as those areas in which C. imicola populations efficiently transmitted the virus.

Modelling the distributions and spatial coincidence of bluetongue vectors Culicoides imicola and the Culicoides obsoletus group throughout the Iberian peninsula

Data obtained by a Spanish national surveillance programme in 2005 were used to develop climatic models for predictions of the distribution of the bluetongue virus (BTV) vectors Culicoides imicola Kieffer (Diptera: Ceratopogonidae) and the Culicoides obsoletus group Meigen throughout the Iberian peninsula. Models were generated using logistic regression to predict the probability of species occurrence at an 8-km spatial resolution. Predictor variables included the annual mean values and seasonalities of a remotely sensed normalized difference vegetation index (NDVI), a sun index, interpolated precipitation and temperature. Using an information-theoretic paradigm based on Akaike's criterion, a set of best models accounting for 95% of model selection certainty were selected and used to generate an average predictive model for each vector. The predictive performances (i.e. the discrimination capacity and calibration) of the average models were evaluated by both internal and external validation. External validation was achieved by comparing average model predictions with surveillance programme data obtained in 2004 and 2006. The discriminatory capacity of both models was found to be reasonably high. The estimated areas under the receiver operating characteristic (ROC) curve (AUC) were 0.78 and 0.70 for the C. imicola and C. obsoletus group models, respectively, in external validation, and 0.81 and 0.75, respectively, in internal validation. The predictions of both models were in close agreement with the observed distribution patterns of both vectors. Both models, however, showed a systematic bias in their predicted probability of occurrence: observed occurrence was systematically overestimated for C. imicola and underestimated for the C. obsoletus group. Average models were used to determine the areas of spatial coincidence of the two vectors. Although their spatial distributions were highly complementary, areas of spatial coincidence were identified, mainly in Portugal and in the southwest of peninsular Spain. In a hypothetical scenario in which both Culicoides members had similar vectorial capacity for a BTV strain, these areas should be considered of special epidemiological concern because any epizootic event could be intensified by consecutive vector activity developed for both species during the year; consequently, the probability of BTV spreading to remaining areas occupied by both vectors might also be higher.

Fleas parasitizing domestic dogs in Spain

In addition to their importance to veterinary clinical practice as ectoparasites, fleas of domestic dogs are of special concern because they can be vectors of disease, including zoonoses. Flea assemblages parasitizing domestic dogs usually comprise several flea species whose distribution is determined by factors acting at several scales. Knowledge of these factors will aid in assessment of the distribution patterns of flea parasitism, and is an important tool in developing control strategies and in evaluation of flea-borne disease risk in dogs and humans. In this survey we used data from 744 domestic dogs from 79 localities in Spain to explore the associations between the abundance of flea species, host-dependent factors (sex and age), and host habitat factors including abode (farm, house with garden, apartment), location (urban or rural), the presence of other pets, and dog activity (measured as the frequency with which dogs left their abode). We also considered environmental factors including the time of year and mean annual temperature and rainfall. Variations in flea community structure at infracommunity and component community levels were also explored. Four flea species were found parasitizing dogs. Ctenocephalides felis was the most abundant (88.02% of fleas identified), followed by Ctenocephalides canis (10.38%), Pulex irritans (1.47%) and Echidnophaga gallinacea (0.13%). Overall flea abundance was higher on dogs living on farms than in apartments, as was the abundance of Ct. felis, Ct. canis and P. irritans. Ct. felis was more abundant on dogs living in houses than in apartments, but the reverse was found for P. irritans. Overall flea abundance and Ct. canis abundance were highest in rural areas, whereas the presence of other pets sharing the abode was associated with higher overall flea abundance and Ct. felis abundance. Only P. irritans abundance was positively related to the activity of dogs. Ct. canis and P. irritans abundances were higher during the warm period of the year. Mean annual temperature was negatively correlated with overall, Ct. canis and P. irritans abundances, but positively related to Ct. felis abundance. Annual rainfall was negatively correlated with Ct. canis and P. irritans abundances. Variations in the number of flea species found on a dog reflected the abundance distribution patterns for each species and their associations with host habitat and environmental factors. At the component community level, flea species richness was inversely related to annual mean temperature. The structure of flea assemblages on dogs was mainly associated with host habitat and environmental variables, and not with host-dependent variables. However, a large amount of variation in flea abundance remained unexplained, suggesting the effect of other non-controlled factors.

Effects of vaccination against viral haemorrhagic disease and myxomatosis on long-term mortality rates of European wild rabbits

The effects of vaccination against myxomatosis and viral haemorrhagic disease (VHD) on long-term mortality rates in European rabbits (Oryctolagus cuniculus) were studied from 1993 to 1996 by radiotracking a free-living population of wild rabbits. During the three months after immunisation, unvaccinated young rabbits weighing between 180 and 600 g were 13.6 times more likely to die than vaccinated young rabbits. In adult rabbits, vaccination did not significantly decrease mortality, mainly owing to the high proportion of rabbits which had previously been exposed to the antigens of both diseases. Compared with adult rabbits with natural antibodies to VHD, rabbits without these antibodies were 5.2 times more likely to die of VHD during annual outbreaks.

Correlates of helminth community in the red-legged partridge (Alectoris rufa L.) in Spain

Between 1992 and 1996, 587 wild red-legged partridges (Alectoris rufa) from 16 Spanish provinces were examined to study the variations of helminth communities in this game species across a broad geographical area. The survey revealed 13 species of helminth parasites. Dicrocoelium sp.. Rhabdometra nigropunctata, and Cheilospirura gruweli were the most common species, whereas Raillietina bolivari, Choanotaenia infundibulum, Tetrameres sp., and Capillaria anatis were the most rare. Subulura suctoria, Heterakis gallinarum, Heterakis tenuicaudata, Capillaria contorta, Trichostrongylus tenuis, and Raillietina tetragona occurred with intermediate frequencies. The abundance of C. gruweli, S. suctoria, H. tenuicaudata, T. tenuis, and R. tetragona was inversely correlated to latitude and directly correlated to yearly mean temperature, whereas the abundance of Dicrocoelium sp. was directly correlated to latitude and inversely correlated to yearly mean temperature. The abundance of R. tetragona was inversely correlated to latitude and yearly mean humidity. The number of helminths per partridge and the number of helminth species per partridge were lower in young birds than in adults. Partridge body condition was inversely correlated to abundance of C. contorta. Richer infracommunities were linked to richer component communities. At the infracommunity level, total number of helminths per partridge and number of helminth species per partridge were inversely correlated to latitude and directly correlated to yearly mean temperature. At the component community level, both species richness and diversity (Simpson's index) were inversely correlated to latitude and directly correlated to mean temperature. Across the broad geographical range of the study area, the helminth parasite communities of red-legged partridges had marked geographical variation in their structure. Our results suggest that this variation is determined by the distribution of both intermediate and definitive hosts. We discuss the implications of this variation for the hypothesis that supplementary releases of captive-bred partridges for sport hunting can affect the helminth fauna of wild red-legged partridges.

Ectoparasite ticks and chewing lice of red-legged partridge, Alectoris rufa, in Spain

During the 1992-1993 and 1993-1994 shooting seasons, 212 wild red-legged partridge, Alectoris rufa (Galliformes: Phaisanide) were captured in 18 Spanish provinces and examined for chewing lice and ticks. Three tick species and six species of chewing lice were found. Ticks (Acari: Ixodidae) Haemaphysalis punctata Canestrini & Fanzago, Hyalomma lusitanicum Koch and Ixodes frontalis Panzer were found at the lowest prevalence (1.4% overall tick prevalence). The louse (Mallophaga) species, Goniodes dispar Burmeister (Goniodidae) (52.8%) and Cuclotogaster obscurior Hopkins (Philopteridae) (28.8%) were the most prevalent, while Goniocotes obscurus Giebel (Philopteridae) (10.8%), Menopon pallens Clay (Menoponidae) (7.5%) and Menacanthus lyali Rodriguez et al. (Menoponidae) (3.3%) were found at medium to low prevalence. Columbicola columbae columbae Linnaeus (Philopteridae) was found at the lowest prevalence (0.5%). The intensity of C. obscurior and overall intensity of all lice species were directly related to the environmental mean temperature and the Normalized Difference Vegetation Index (NDVI), whereas intensity of G. dispar was directly related to NDVI only. The intensity of G. dispar, C. obscurior, all louse intensity, and louse species richness were higher in male than female birds. Intensity of each louse species, all louse intensity and louse species richness were inversely associated with the nutritional index. No relationship was observed between bird age and louse intensity or species richness.

Epidemiology of viral haemorrhagic disease and myxomatosis in a free-living population of wild rabbits

From January 1993 to June 1996, the epidemiology of myxomatosis and viral haemorrhagic disease (VHD) was studied in a free-living population of wild rabbits (Oryctolagus cuniculus) in Spain by means of serological surveys and radiotracking. Myxomatosis was endemic and associated with the breeding period. Its serological pattern was characterised by a 100 per cent prevalence of antibodies in adult rabbits and a rapid increase in antibodies in young rabbits in their first year. No mortality from myxomatosis was detected in adults, and mortality in young rabbits could not be estimated because of interference by predators and scavengers and the deaths of many radiotagged rabbits inside their burrows. VHD was also an endemic disease associated with the breeding period. Adults had a higher prevalence of antibodies against VHD than young rabbits, reaching values of 80 to 90 per cent. During the study, there was an increase in rabbit numbers as a result of a decrease in mortality from predation which was associated with an increase in mortality due to VHD and in the prevalence of antibodies to VHD. Mortality from VHD was lower in rabbits with VHD antibodies than in seronegative rabbits, but some mortality from the disease was also detected in seropositive rabbits. The annual mean mortality rate due to VHD in adult rabbits was estimated to be 21.8 per cent.

[Molecular studies in Cuban patients with progressive external ophthalmoplegia]

INTRODUCTION

The mitochondria, subcellular organelles which possess their own DNA (mtDNA), produce most of the energy, in the form of ATP, which is necessary for life. This mtDNA may have diverse molecular defects which have been associated with a great variety of clinical syndromes. Deletions in mtDNA are one of the common mutations in patients with mitochondrial myopathies, which in the great majority present with the common symptom of progressive external ophthalmoplegia. In this study we report our findings in eight Cuban families with suspected mitochondrial disease.

OBJECTIVES

To characterize these patients from the molecular point of view, which would allow a preliminary understanding of the behavior of these deletions in Cuban patients.

PATIENTS AND METHODS

We studied nine patients from eight Cuban families in whom mitochondrial encephalomyopathy was suspected. We analyzed the presence of ragged red fibres, the enzymatic activity of the mitochondrial respiratory chain and detection of mtDNA mutations. We used the technique of restriction length polymorphism analysis for detection of deletions.

RESULTS

Histochemical studies showed the presence of COX negative ragged red fibres in seven of the patients studied. The enzymatic activity of the mitochondrial respiratory chain was normal in all the patients. We detected four patients with single deletions of mtDNA, and one with multiple deletions and of the patients had the A3243G mutation.

CONCLUSIONS

With the methods used we were able to determine the presence of a mitochondrial disorder in seven of the eight families studied and deletions of mtDNA were detected as the cause of the illness in five. The disorder was always associated with progressive external ophthalmoplegia and COX negative ragged red fibres.

[Inflammatory demyelinating chronic polyneuropathy: a contribution to the characterization of the disease]

INTRODUCTION AND OBJECTIVE

The chronic inflammatory demyelinating polyneuropathy (CIDP) is a controversial sickness. No doubt it is still a diagnosis without a strict nosologic delimitation until we acquire a greater knowledge about the underlying mechanisms, or whether a specific marker is found. We evaluated its clinical and laboratory findings, to contribute to its characterization in our environment.

PATIENTS AND METHODS

We reviewed the records of 37 patients diagnosed with CIDP between 1986 and 1997. They were grouped in as to sex, age, beginning age (BA), evolution time, race, clinical form, symptoms, signs and evolutive profile. We analyzed the cytochemic and immunologic studies of cerebrospinal fluid (CSF) as well as sural nerve biopsy.

RESULTS AND CONCLUSIONS

We demonstrated a predominance of BA between the fifth and sixth decades, and the presentation of a mixed polyradiculoneuropathy with motor predominance and a chronic progressive evolution. It was positively correlated with protein concentration levels in CSF, elevated in the 73.5% of the patients. There was an increase in the permeability of the blood brain barrier (BBB) in 50.8%, IgG intrathecal synthesis in 5.08 and oligoclonal bands in 8.8%. We found lost of myelin sheats in 90.6% of sural nerves and onion-bulbs formation in 60.5%, which demonstrated the high sensitivity of this study to confirm the diagnosis of demyelinating process as essential substrate in the illness.

Once-daily therapy for H. pylori infection: a randomized comparison of four regimens

OBJECTIVE

We sought to determine the efficacy and tolerability of novel, once-daily therapies in the treatment of Helicobacter pylori infection.

METHODS

One hundred sixty subjects with H. pylori infection documented by endoscopic biopsy or serology plus 13C-urea breath test were randomly assigned to omeprazole 80 mg q.d. and metronidazole extended-release formulation 750 mg q.d. for 10 days (OM); OM plus amoxicillin 1.5 g q.d. for 10 days (OMAm); OM plus azithromycin 500 mg q.d. for 7 days (OMAz); or OM plus clarithromycin 1 g q.d. for 10 days (OMCI). A repeat breath test was done 6 wk after the completion of therapy. Subjects were considered compliant if they took > or = 80% of each study medication as prescribed.

RESULTS

Intent-to-treat eradication rates were OM = 8% (95% confidence interval [CI], 2-20%), OMAm = 35% (95% CI, 21-52%), OMAz = 65% (95% CI, 48-79%), and OMCI = 78% (95% CI, 62-89%). Lack of compliance was seen in 5% of subjects given OM, 8% given OMAm, 3% given OMAz, and 15% given OMCI.

CONCLUSIONS

This pilot study demonstrated that once-daily triple therapy with high-dose omeprazole, metronidazole extended-release formulation, and clarithromycin achieved an eradication rate approaching 80%. Further study may permit development of optimal once-daily dosing and enhance eradication rates.

Spinocerebellar ataxia 2 (SCA2): morphometric analyses in 11 autopsies

Eleven autopsies of patients from the large founder-population with dominantly inherited spinocerebellar ataxia 2 (SCA2) in Holguín, Cuba, were analyzed by the same observers, including quantitative microscopic evaluation. As expected in this disease with highly unstable polyglutamine expansions, considerable variability was observed, which correlated to age at onset and to progression of clinical symptoms. The degeneration of the olivopontocerebellar regions as in classical olivopontocerebellar atrophy occurred early and severely in SCA2. The neuropathological progression soon included neuronal loss in the substantia nigra, striatum, pallidum and later even the neocortex, while the dentate nucleus was consistently spared. This widespread degeneration pattern goes clearly beyond purely cerebellar degenerations such as SCA5 and 6 and beyond spinocerebellar degenerations such as SCA1, 3, 7, also involves regions known to degenerate in Huntington's disease, and is quite similar to the degeneration pattern in sporadic patients with multi-system atrophy.

[Electrophysiological characteristics of inflammatory demyelinating chronic polyneuropathy]

INTRODUCTION

The electrophysiological studies, specially nerve conduction studies (NCS) constitute one of the basic supports to obtain an early and accurate diagnosis to perform a successful treatment in the chronic inflammatory demyelinating polyneuropathy (CIDP). There is nevertheless, no definite consensus about which would be the most specific and sensitive electric variables in the illness.

OBJECTIVE

To describe the NCS findings in a group of patients with this diagnosis, in order to contribute to its electrophysiological characterization.

PATIENTS AND METHODS

We an analyzed the NCS on 37 patients diagnosed with CIDP. The NCS were done using standard techniques. These studies were assessed according to the reference values of a normative study on 90 healthy persons. We performed somatosensory evoked potentials (SSEP), visual (VEP) and brainstem auditory evoked potentials (BAEP) in 8 patients, and motor potentials (MP) by transcranial magnetic stimulation in 3.

RESULTS

The registered values are presented in media comparison tables (cases/controls). The frequency of abnormalities in latencies (L), amplitudes, conduction velocity (CV) and the presence of partial blocks is analyzed. The affectation of the evoked potentials in some patients, demonstrated subclinical concomitant demyelinization of the central nervous system.

CONCLUSIONS

The most sensitive electrophysiological parameters are the motor CV, the total duration and distal latencies, that gives these variables a confident value in the initial stages of the illness. The relative normality of conduction through the sural nerve, even in the presence of severe abnormalities of the median nerve constitutes a repetitive and specific pattern to this kind of illness.

[Neuropathy of leprosy: characteristics of cases in 1962-1995]

INTRODUCTION

Neuropathy due to leprosy is the most frequent cause of peripheral nervous system disorders due to an infective agent, one of the commonest aetiologies of peripheral neuropathy, and also one of the few peripheral neuropathies which is curable. Hansen's disease, initially and predominantly involves the skin, so it is not usually seen by a neurologist; a neurologist sees cases which are difficult to diagnose and often after the condition has been ruled out by other doctors from other medical specialties.

PATIENTS AND METHODS

In the National Institute of Neurology and Neurosurgery of La Habana, Cuba, 18 nerve biopsies were studied (during its history), that had been diagnosed as leprous neuropathy. We reviewed the clinical histories of all the patients admitted to this centre. The sample was characterized by: age, sex, neurological clinical picture, nerves most affected, skin lesions, electrophysiological studies and a description of the anatomopathological findings.

RESULTS AND DISCUSSION

Most patients were male and all (100%) were adults of 'working age' (19-65 years). The most frequent neuropathic pattern was multiple mono-neuropathy (78%) and the quality, purely sensitive or mixed was predominantly sensitive (100%). The nerves most affected were the ulnar (10 patients) and median (6 patients). The most frequent skin lesions were anesthetic maculae. Anatomo-pathological study showed inflammatory infiltration in all patients and the bacillus was absent in only one case.

Whole-body protein synthesis in growing barrows: diurnal and day-to-day variation and the effect of site of tracer infusion and sampling

In the first experiment, two catheters were placed in one of three sites for infusion and sampling (vena cava and vena cava with 7 cm between catheter tips, VC/VC, n = 5; right ventricle and atrium, RV/RA, n = 5; anterior aorta and left ventricle, AA/LV, n = 4) to determine the effect of site on the measurement of CO2 and leucine kinetics. Pigs received a 6-h continuous i.v. infusion of NaH13CO3 (1.45 µmol h−1 kg−1, preceded by a priming dose of 2.05 µmol kg−1) and of L[1-13C]leucine (9.7 µmol h−1 kg−1, preceded by a priming dose of 9.7 µmol kg−1), the following day. No effect (P > 0.10) of site was observed on NaH13CO3 recovery rate, leucine irreversible loss rate (leucine ILR) and leucine used for protein synthesis (LS). A tendency (P < 0.10) for increased leucine oxidation (LO) was observed with the VC/VC compared to the RV/RA sites. In the second experiment, six growing barrows with catheters in the VC/VC site were infused as earlier with NaH13CO3 and L[1-13C]leucine for three different 6h periods (12:00 to 18:00 h, first day; 20:00 to 02:00 h, night; 12:00 to 18:00 h, second day) to determine the diurnal and day-to-day variation of CO2 and leucine kinetics. No effect (P > 0.10) of period was observed on NaH13CO3 recovery rate, leucine ILR and LS. The LO was lower (P < 0.05) on the second day compared with the first day (day-to-day variation) while similar (P > 0.10) LO was observed between the first day and night (diurnal variation). Together, these results indicate that 1) the VC/VC site can be used for L[1-13C]leucine and NaH13CO3 infusions, 2) NaH13CO3 recovery studies can be performed either the day preceding or following the measurement of substrate and 3) protein synthesis estimated from a 6-h infusion period can be extrapolated to the 24 h periods under conditions of frequent feeding. Key words: Pigs, leucine, protein synthesis, tracer techniques, diurnal variation

Effect of proton-pump inhibitor therapy on diagnostic testing for Helicobacter pylori

BACKGROUND

Proton-pump inhibitor therapy may cause false-negative results on Helicobacter pylori diagnostic testing.

OBJECTIVE

To determine the frequency and duration of conversion of urea breath test results from positive to negative in patients given a proton-pump inhibitor.

SETTING

Two urban university gastroenterology clinics.

PATIENTS

Patients infected with H. pylori who had positive results on urea breath tests.

INTERVENTION

Lansoprazole, 30 mg/d for 28 days.

MEASUREMENTS

The urea breath test was repeated at 28 days. If the results were negative, testing was repeated 3, 7, 14, and 28 days after completion of therapy until the results reverted to positive.

RESULTS

31 (33%) of 93 patients in whom H. pylori was not eradicated had a negative breath test result while receiving lansoprazole. The proportions of patients whose breath test results were positive after completion of lansoprazole therapy were 91% (95% CI, 83% to 96%) at 3 days, 97% (CI, 90% to 99%) at 7 days, and 100% (CI, 96% to 100%) at 14 days.

CONCLUSION

Patients should not receive proton-pump inhibitors for 2 weeks before receiving the urea breath test for H. pylori infection.

Expression in Escherichia coli of the lpdA gene, protein sequence analysis and immunological characterization of the P64k protein from Neisseria meningitidis

By making use of recombinant DNA technology it is possible to characterize meningococcal outer membrane proteins (OMPs) capable of stimulating a host immune response. The lpdA gene, which codes for an OMP (P64k) from Neisseria meningitidis, was cloned in Escherichia coli. The recombinant protein was recognized by sera from patients convalescing from meningococcal disease. The monoclonal antibodies obtained against the recombinant protein recognized the natural protein on a Western blot, and monoclonal antibody 114 was assayed in ELISA with a panel of 85 N. meningitidis strains. The protein was recognized in 81 strains (95.3%); the strains that were not recognized were neither epidemic nor isolated from systemic disease. The complete amino acid sequence of P64k was obtained by automatic sequencing and MS.

[Eumycetic mycetoma due to Madurella mycetomatis. Report of six cases.]

We report six cases of mycetoma due to Madurella mycetomatis. Five men and a woman from 28 to 70 years of age, and a history of one to ten years. In four of them the foot was affected, in another the wrist, and one exceptional case with neck involvement after an iguana bite. The response to treatment was irregular and not satisfactory.

Gastrointestinal helminth parasites in stray cats from the mid-Ebro Valley, Spain

Gastrointestinal helminths were collected from 58 necropsied stray cats (Felis catus) in the mid-Ebro Valley, North-East Spain, from December 1989 to March 1992. The prevalence was 89.7%, with those of individual parasites being Toxocara cati 55.2%C, Ancylostoma tubaeforme 29.3% Joyeuxiella pasqualei 55.2%, Diplopylidium acanthotetra 20.7%, Dipylidium caninum 20.7%, Mesocestoides spp. 13.8%, Taenia taeniformis 8.6% and Diplopylidium nölleri 8.6%. In relation to sex, the differences were not significant. However, the season of the year significantly affected the prevalence of A. tubaeforme and D. acanthotetra.

Inhibition by CaNa2EDTA of local tissue damage induced by Bothrops asper (terciopelo) venom: application in horse immunization for antivenom production

The ability of the chelating agent CaNa2EDTA to inhibit local tissue damage induced by Bothrops asper venom was studied in mice and in horses used for polyvalent (Crotalinae) antivenom production. CaNa2EDTA was devoid of toxicity when injected i.m. or s.c. inducing only a mild edema. Preincubation of B. asper venom with CaNa2EDTA inhibited hemorrhagic and dermonecrotic activities, but did not reduce edema-forming and myotoxic effects. A group of horses initially immunized with native venoms developed less severe local tissue reactions when injected with booster doses of venom and CaNa2EDTA than when receiving booster injections of venom alone, although they showed a similar antivenom response. Moreover, antivenoms produced from plasmas of horses that received booster injections of either venom alone or venom plus CaNa2EDTA had similar neutralizing activity against lethal, hemorrhagic and coagulant effects induced by B. asper venom. The similar antibody response was corroborated by Western blotting using crude venom and by an ELISA that estimates anti-myotoxin titer. It is concluded that the chelating agent CaNa2EDTA reduces the extent of local tissue damage induced by B. asper venom, without affecting the immune response of horses against pharmacologically-relevant venom components.

Effect of blood on rapid urease testing of gastric mucosal biopsy specimens

BACKGROUND

The effect of blood on rapid urease tests is uncertain. We assessed the effect of soaking gastric biopsy specimens in blood on the results of both agar gel (CLOtest) and strip (Pyloritek) rapid urease tests.

METHODS

One hundred patients undergoing endoscopy had four adjacent biopsy specimens taken from normal appearing mucosa in the antrum. Two biopsies were soaked in blood for 1 minute; one specimen was placed on a CLOtest and one on a Pyloritek. The other two biopsy specimens were placed on CLOtest and Pyloritek without soaking in blood. The same process was performed with four adjacent biopsy specimens from the gastric body. CLOtests were read at 1, 4, and 24 hours; Pyloritek results were read at 1 hour.

RESULTS

The number of positive tests for the blood-soaked and standard biopsy specimens were comparable at all times for both rapid urease tests. Discordant results between the blood-soaked and standard specimens were seen in 17 of 400 test comparisons (4%): in 8 of these only the blood-soaked specimen was positive, and in 9 only the standard specimen was positive.

CONCLUSIONS

"Contamination" of biopsy specimens with blood does not alter rapid urease test results.

Randomized comparison of ranitidine bismuth citrate-based triple therapies for Helicobacter pylori

OBJECTIVES

In an attempt to increase the efficacy and simplicity of FDA-approved regimens for Helicobacter pylori, we studied (1) addition of an inexpensive antibiotic (amoxicillin) to twice-daily ranitidine bismuth citrate (RBC)-clarithromycin dual therapy, and (2) substitution of RBC for bismuth subsalicylate + H2-receptor antagonist in bismuth-based triple therapy.

METHODS

Subjects with previously untreated Helicobacter pylori infection documented by 13C-urea breath test plus either endoscopic biopsy or serology were randomly assigned to a 2-wk course of (1) RBC 400 mg b.i.d., amoxicillin 1 g b.i.d., and clarithromycin 500 mg b.i.d. (RAC), or (2) RBC 400 mg b.i.d., metronidazole 250 mg t.i.d., and tetracycline 500 mg t.i.d. (RMT). Repeat breath test was performed 4 wk after the completion of therapy.

RESULTS

Intent-to-treat and per-protocol cure rates for RAC were 46 of 50 patients (92%) and 45 of 47 patients (96%); for RMT they were 40 of 50 patients (80%) and 37 of 42 patients (88%). Study drugs were stopped due to side effects in three patients (6%) taking RAC and six patients (12%) taking RMT.

CONCLUSIONS

Twice-daily RBC-based triple therapy with clarithromycin and amoxicillin produces Helicobacter pylori eradication rates over 90%, which is comparable to rates seen with proton pump inhibitor-based triple therapies. RBC also may be substituted for bismuth subsalicylate and an + H2-receptor antagonist in standard bismuth-based triple therapy.