Temporal and spatial association of Streptococcus suis infection in humans and porcine reproductive and respiratory syndrome outbreaks in pigs in northern Vietnam.

Porcine reproductive and respiratory syndrome (PRRS) outbreaks in pigs are associated with increased susceptibility of pigs to secondary bacterial infections, including Streptococcus suis - an important zoonotic pathogen causing bacterial meningitis in humans. This case-control study examined the association between human S. suis infection and PRRS outbreaks in pigs in northern Vietnam. We included 90 S. suis case-patients and 183 non-S. suis sepsis controls from a referral hospital in Hanoi in 2010, a period of major PRRS epizootics in Vietnam. PRRS exposure was determined using data from the National Centre of Veterinary Diagnosis. By univariate analysis, significantly more S. suis patients were reported residing in or adjacent to a PRRS district compared to controls [odds ratio (OR) 2·82, 95% confidence interval (CI) 1·35-5·89 and OR 3·15, 95% CI 1·62-6·15, respectively]. Only residency in adjacent districts remained significantly associated with risk of S. suis infection after adjusting for sex, occupation, and eating practices. SaTScan analysis showed a possible cluster of S. suis infection in humans around PRRS confirmed locations during the March-August period. The findings indicate an epidemiological association between PRRS in pigs and S. suis infections in humans. Effective strategies to strengthen control of PRRS in pigs may help reduce transmission of S. suis infection to humans.

High levels of antimicrobial resistance among escherichia coli isolates from livestock farms and synanthropic rats and shrews in the Mekong Delta of Vietnam.

In Mekong Delta farms (Vietnam), antimicrobials are extensively used, but limited data are available on levels of antimicrobial resistance (AMR) among Escherichia coli isolates. We performed a structured survey of AMR in E. coli isolates (n = 434) from 90 pig, chicken, and duck farms. The results were compared with AMR among E. coli isolates (n = 234) from 66 small wild animals (rats and shrews) trapped on farms and in forests and rice fields. The isolates were susceptibility tested against eight antimicrobials. E. coli isolates from farmed animals were resistant to a median of 4 (interquartile range [IQR], 3 to 6) antimicrobials versus 1 (IQR, 1 to 2) among wild mammal isolates (P < 0.001). The prevalences of AMR among farmed species isolates (versus wild animals) were as follows: tetracycline, 84.7% (versus 25.6%); ampicillin, 78.9% (versus 85.9%); trimethoprim-sulfamethoxazole, 52.1% (versus 18.8%); chloramphenicol, 39.9% (versus 22.5%); amoxicillin-clavulanic acid, 36.6% (versus 34.5%); and ciprofloxacin, 24.9% (versus 7.3%). The prevalence of multidrug resistance (MDR) (resistance against three or more antimicrobial classes) among pig isolates was 86.7% compared to 66.9 to 72.7% among poultry isolates. After adjusting for host species, MDR was ∼8 times greater among isolates from wild mammals trapped on farms than among those trapped in forests/rice fields (P < 0.001). Isolates were assigned to unique profiles representing their combinations of susceptibility results. Multivariable analysis of variance indicated that AMR profiles from wild mammals trapped on farms and those from domestic animals were more alike (R(2) range, 0.14 to 0.30) than E. coli isolates from domestic animals and mammals trapped in the wild (R(2) range, 0.25 to 0.45). The results strongly suggest that AMR on farms is a key driver of environmental AMR in the Mekong Delta.

Determination of cut-off cycle threshold values in routine RT-PCR assays to assist differential diagnosis of norovirus in children hospitalized for acute gastroenteritis.

Norovirus (NV) is an important cause of acute gastroenteritis in children, but is also frequently detected in asymptomatic children, which complicates the interpretation of NV detection results in both the clinical setting and population prevalence studies. A total of 807 faecal samples from children aged <5 years hospitalized for acute gastroenteritis were collected in Thai Binh, Vietnam, from January 2011 to September 2012. Real-time RT-PCR was used to detect and quantify NV-RNA in clinical samples. A bimodal distribution of cycle threshold (Ct) values was observed in which the lower peak was assumed to represent cases for which NV was the causal agent of diarrhoea, whereas the higher peak was assumed to represent cases involving an alternative pathogen other than NV. Under these assumptions, we applied finite-mixture modelling to estimate a threshold of Ct <21·36 (95% confidence interval 20·29-22·46) to distinguish NV-positive patients for which NV was the likely cause of diarrhoea. We evaluated the validity of the threshold through comparisons with NV antigen ELISA results, and comparisons of Ct values in patients co-infected with rotavirus. We conclude that the use of an appropriate cut-off value in the interpretation of NV real-time RT-PCR results may improve differential diagnosis of enteric infections, and could contribute to improved estimates of the burden of NV disease.

Population susceptibility to a variant swine-origin influenza virus A(H3N2) in Vietnam, 2011-2012.

A reassortant swine-origin A(H3N2) virus (A/swine/BinhDuong/03-9/2010) was detected through swine surveillance programmes in southern Vietnam in 2010. This virus contains haemagglutinin and neuraminidase genes from a human A(H3N2) virus circulating around 2004-2006, and the internal genes from triple-reassortant swine influenza A viruses (IAVs). To assess population susceptibility to this virus we measured haemagglutination inhibiting (HI) titres to A/swine/BinhDuong/03-9/2010 and to seasonal A/Perth/16/2009 for 947 sera collected from urban and rural Vietnamese people during 2011-2012. Seroprevalence (HI ⩾ 40) was high and similar for both viruses, with 62·6% [95% confidence interval (CI) 59·4-65·7] against A/Perth/16/2009 and 54·6% (95% CI 51·4-57·8%) against A/swine/BinhDuong/03-9/2010, and no significant differences between urban and rural participants. Children aged <5 years lacked antibodies to the swine origin H3 virus despite high seroprevalence for A/Perth/16/2009. These results reveal vulnerability to infection to this contemporary swine IAV in children aged <5 years; however, cross-reactive immunity in adults would likely limit epidemic emergence potential.

High levels of contamination and antimicrobial-resistant non-typhoidal Salmonella serovars on pig and poultry farms in the Mekong Delta of Vietnam.

We investigated the prevalence, diversity, and antimicrobial resistance (AMR) profiles of non-typhoidal Salmonella (NTS) and associated risk factors on 341 pig, chicken, and duck farms in Dong Thap province (Mekong Delta, Vietnam). Sampling was stratified by species, district (four categories), and farm size (three categories). Pooled faeces, collected using boot swabs, were tested using ISO 6575: 2002 (Annex D). Isolates were serogrouped; group B isolates were tested by polymerase chain reaction to detect S. Typhimurium and (monophasic) serovar 4,[5],12:i:- variants. The farm-level adjusted NTS prevalence was 64·7%, 94·3% and 91·3% for chicken, duck and pig farms, respectively. Factors independently associated with NTS were duck farms [odds ratio (OR) 21·2], farm with >50 pigs (OR 11·9), pig farm with 5-50 pigs (OR 4·88) (vs. chickens), and frequent rodent sightings (OR 2·3). Both S. Typhimurium and monophasic S. Typhimurium were more common in duck farms. Isolates had a high prevalence of resistance (77·6%) against tetracycline, moderate resistance (20-30%) against chloramphenicol, sulfamethoxazole-trimethoprim, ampicillin and nalidixic acid, and low resistance (<5%) against ciprofloxacin and third-generation cephalosporins. Multidrug resistance (resistance against ⩾3 classes of antimicrobial) was independently associated with monophasic S. Typhimurium and other group B isolates (excluding S. Typhimurium) and pig farms. The unusually high prevalence of NTS on Mekong Delta farms poses formidable challenges for control.

An epidemiological investigation of Campylobacter in pig and poultry farms in the Mekong delta of Vietnam.

Campylobacter are zoonotic pathogens commonly associated with gastroenteritis. To assess the relevance of Campylobacter in Vietnam, an economically transitioning country in SE Asia, we conducted a survey of 343 pig and poultry farms in the Mekong delta, a region characterized by mixed species farming with limited biosecurity. The animal-level prevalence of Campylobacter was 31·9%, 23·9% and 53·7% for chickens, ducks and pigs, respectively. C. jejuni was predominant in all three host species, with the highest prevalence in pigs in high-density production areas. Campylobacter isolates demonstrated high levels of antimicrobial resistance (21% and 100% resistance against ciprofloxacin and erythromycin, respectively). Multilocus sequence type genotyping showed a high level of genetic diversity within C. jejuni, and predicted C. coli inter-species transmission. We suggest that on-going intensification of animal production systems, limited biosecurity, and increased urbanization in Vietnam is likely to result in Campylobacter becoming an increasingly significant cause of human diarrhoeal infections in coming years.

Different strategies for auditory word recognition in healthy versus normal aging.

To explore the effects of commonly encountered pathology on auditory recognition strategies in elderly participants, magnetoencephalographic (MEG) brain activation patterns and performance were examined in 30 elderly [18 controls and 12 elderly with mild cognitive impairment (MCI) or probable Alzheimer's disease (AD)]. It was predicted that participants with known pathology would reveal different networks of brain activation, compared to healthy elderly, which should correlate with poorer performance. Participants heard a list of words representing common objects, twice. After 20 minutes a list of new and old words was presented and participants judged whether each word was heard earlier. MEG responses were analyzed using a semiautomated source modeling procedure. A cluster analysis using all subjects' MEG sources revealed three dominant patterns of activity which correlated with IQ and task performance. The highest performing group revealed activity in premotor, anterior temporal, and superior parietal lobes with little contribution from prefrontal cortex. Performance and brain activation patterns were also compared for individuals with or without abnormalities such as white matter hyperintensities and/or volume reduction evidenced on their MRIs. Memory performance and activation patterns for individuals with white matter hyperintensities resembled the group of MCI/AD patients. These results emphasize the following: (1) general pathology correlates with cognitive decline and (2) full characterization of the health of elderly participants is important in studies of normal aging since random samples from the elderly population are apt to include individuals with subclinical pathology that can affect cognitive performance.

Detection of potentially novel paramyxovirus and coronavirus viral RNA in bats and rats in the Mekong Delta region of southern Viet Nam.

Bats and rodents are being increasingly recognized as reservoirs of emerging zoonotic viruses. Various studies have investigated bat viruses in tropical regions, but to date there are no data regarding viruses with zoonotic potential that circulate in bat and rat populations in Viet Nam. To address this paucity of data, we sampled three bat farms and three wet markets trading in rat meat in the Mekong Delta region of southern Viet Nam. Faecal and urine samples were screened for the presence of RNA from paramyxoviruses, coronaviruses and filoviruses. Paramyxovirus RNA was detected in 4 of 248 (1%) and 11 of 222 (4.9%) bat faecal and urine samples, respectively. Coronavirus RNA was detected in 55 of 248 (22%) of bat faecal samples; filovirus RNA was not detected in any of the bat samples. Further, coronavirus RNA was detected in 12 of 270 (4.4%) of rat faecal samples; all samples tested negative for paramyxovirus. Phylogenetic analysis revealed that the bat paramyxoviruses and bat and rat coronaviruses were related to viruses circulating in bat and rodent populations globally, but showed no cross-species mixing of viruses between bat and rat populations within Viet Nam. Our study shows that potentially novel variants of paramyxoviruses and coronaviruses commonly circulate in bat and rat populations in Viet Nam. Further characterization of the viruses and additional human and animal surveillance is required to evaluate the likelihood of viral spillover and to assess whether these viruses pose a risk to human health.

Inhibition of human telomerase by a retrovirus expressing telomeric antisense RNA.

Human telomerase, the RNA-dependent DNA polymerase that adds TTAGGG repeats to chromosome ends, is selectively expressed in immortalised cells and most tumours, suggesting a potential role for telomerase inhibitors in cancer therapy. Replication-deficient retroviruses were used to determine whether mRNA containing UUAGGG, the complementary sequence to the template region of the hTR telomerase RNA, is sufficient to inhibit telomerase activity. Telomerase activities measured by the telomeric repeat amplification protocol (TRAP) assay in extracts prepared from immortalised mouse fibroblasts, human HeLa cells and human kidney carcinoma cells were inhibited by 75% or greater in 26 of 56 cell clones expressing UUAGGG. Telomerase activity was not inhibited by expression of mRNA containing a transposed sequence, GGGAUU. Telomerase activities in vivo were inferred from changes in cellular morphology, proliferation capacity, growth rate and measurement of the content of telomere DNA. Giant senescent-like cells emerged shortly after cloning mouse PA317 and human HeLa cells expressing UUAGGG. The fraction of giant cells varied from 100% at the fifth population doubling (PD) in one culture to 2-6% at 50 PD in several other cultures. Giant cells were absent in all parental cells and clones expressing GGGAUU. The average cellular content of telomere DNA was independent of telomerase activity over 50 PD. The results indicate that expression of RNA complementary to the template region of hTR is sufficient to inhibit telomerase in vitro and in vivo, but that the effect of inhibition on individual cells is highly variable.

Measurement of telomeric DNA content in human tissues.

Telomeres, nucleoprotein complexes at the ends of eukaryotic chromosomes, are 10-12 kbp in length in somatic cells, but as small as 1-2 kbp in rapidly growing cancer cells. Southern blot analysis is currently the standard method for the measurement of telomere length. However, accurate determinations are not possible when DNA is broken or scant. To avoid these problems, a slot blot assay that quantitates the relative content, instead of length, of telomere DNA was developed. The relative contents of telomere DNA determined by this slot blot assay were directly proportional to the relative lengths of telomere DNA determined in parallel by Southern blot analysis. Relative telomere DNA content could be measured in samples containing as little as 15 ng of total DNA. Relative telomere DNA content, but not length, also was unaffected by breakage of DNA into fragments 1 kbp or less in length.

Study of intragastric administration of doxycycline: pharmacokinetics including body fluid, endometrial and minimum inhibitory concentrations.

The objectives of this study were to determine the pharmacokinetics and tissue concentrations of doxycycline after repeated intragastric administration, and to determine the minimum inhibitory concentrations (MIC) for equine pathogenic bacteria. In experiment 1, 2 mares received a single intragastric dose of doxycycline hyclate (3 mg/kg bwt). Mean peak serum concentration was 0.22 microg/ml 1 h postadministration. In experiment 2, 5 doses of doxycycline hyclate (10 mg/kg bwt), dissolved in water, were administered to each of 6 mares via nasogastric tube at 12 h intervals. The mean +/- s.e. peak serum doxycycline concentration was 0.32+/-0.16 microg/ml 1 h after the first dose and 0.42+/-0.05 microg/ml 2 h after the fifth dose. The mean trough serum concentrations were > 0.16 microg/ml. Highest mean synovial concentration was 0.46+/-0.13 microg/ml and highest mean peritoneal concentration was 0.43+/-0.07 microg/ml, both 2 h after the fifth dose. Highest urine concentration was mean +/- s.e. 145+/-25.4 microg/ml 2 h after the last dose. Highest endometrial concentration was mean +/- s.e. 1.30+/-0.36 microg/ml 3 h after the fifth dose. Doxycycline was not detected in any of the CSF samples. Mean +/- s.e. Vd(area) was 25.3+/-5.0 l/kg and mean t1/2 was 8.7+/-1.6 h. In experiment 3, minimum inhibitory concentrations of doxycycline were determined for 168 equine bacterial culture specimens. The MIC90 was < or = 1.0 microg/ml for Streptococcus zooepidemicus and 0.25 microg/ml for Staphylococcus aureus. Based on drug concentrations achieved in the serum, synovial and peritoneal fluids and endometrial tissues and MIC values determined in the present study, doxycycline at a dose of 10 mg/kg bwt per os every 12 h may be appropriate for the treatment of infections caused by susceptible (MIC < 0.25 microg/ml) gram-positive organisms in horses.

A review of foodborne bacterial and parasitic zoonoses in Vietnam.

Vietnam has experienced unprecedented economic and social development in recent years, and the livestock sector is undergoing significant transformations. Although food animal production is still dominated by small-scale 'backyard' enterprises with mixed crop-livestock or livestock-aquatic systems, there is a trend towards more intensive and vertically integrated operations. Changes in animal production, processing and distribution networks for meat and animal products, and the shift from wet markets to supermarkets will undoubtedly impact food safety risks in Vietnam in unforeseen and complex ways. Here, we review the available published literature on bacterial and parasitic foodborne zoonoses (FBZ) in Vietnam. We report on clinical disease burden and pathogen prevalence in animal reservoirs for a number of important FBZ, and outline opportunities for future research.

MEG-SIM: a web portal for testing MEG analysis methods using realistic simulated and empirical data.

MEG and EEG measure electrophysiological activity in the brain with exquisite temporal resolution. Because of this unique strength relative to noninvasive hemodynamic-based measures (fMRI, PET), the complementary nature of hemodynamic and electrophysiological techniques is becoming more widely recognized (e.g., Human Connectome Project). However, the available analysis methods for solving the inverse problem for MEG and EEG have not been compared and standardized to the extent that they have for fMRI/PET. A number of factors, including the non-uniqueness of the solution to the inverse problem for MEG/EEG, have led to multiple analysis techniques which have not been tested on consistent datasets, making direct comparisons of techniques challenging (or impossible). Since each of the methods is known to have their own set of strengths and weaknesses, it would be beneficial to quantify them. Toward this end, we are announcing the establishment of a website containing an extensive series of realistic simulated data for testing purposes ( http://cobre.mrn.org/megsim/ ). Here, we present: 1) a brief overview of the basic types of inverse procedures; 2) the rationale and description of the testbed created; and 3) cases emphasizing functional connectivity (e.g., oscillatory activity) suitable for a wide assortment of analyses including independent component analysis (ICA), Granger Causality/Directed transfer function, and single-trial analysis.

Recent avian influenza virus A/H5N1 evolution in vaccinated and unvaccinated poultry from farms in Southern Vietnam, January-March 2010.

We report 15 new avian influenza virus A/H5N1 haemagglutinin (HA) sequences sampled from visibly sick domestic poultry in southern Vietnam, between 1 January 2010 and 6 March 2010. These HA sequences form a new sub-clade of the clade 1 H5N1 viruses that have been circulating in Vietnam since 2003/2004. The viruses are characterized by a change from isoleucine to valine at position 514 (I514V) and are 1.8% divergent at the nucleotide level from HA sequences sampled in Vietnam in 2007. Five new amino acid changes were observed at previously identified antigenic sites, and three were located within structural elements of the receptor-binding domain. One new mutation removed a potential N-linked glycosylation site, and a methionine insertion was observed in one virus at the polybasic cleavage site. Five of these viruses were sampled from farms where poultry were vaccinated against H5N1, but there was no association between observed amino acid changes and flock vaccination status. Despite the current lack of evidence for antigenic drift or immune escape in Vietnamese H5N1 viruses, continued surveillance remains a high priority.

Glutamic acid codon suppressors derived from a unique species of glycine transfer ribonucleic acid.

In this paper we describe the successful isolation of glyT-derived GAA suppressors. A glyT+ strain containing glyV55, the gene for a GGA/G-reading, methane sulfonate and hydroxylamine. The cells were plated to select for reversal of auxotrophy due to a trpA(GAA211) mutation. With either mutagen, greater than 85% of the prototrophs obtained were due to suppressors of the trpA mutation. Approximately 12% of the ethyl methane sulfonate-induced and 37% of the hydroxylamine-induced suppressors were shown to be about 25% cotranscucible with metB, as is glyT. The transfer ribonucleic acid from four metB-linked suppressor strains (two from each mutagen) was examined by reversed-phase column (RPC-5) chromatography. In all four cases, the glycyl-transfer ribonucleic acid profile displayed an alteration of glyT transfer ribonucleic acid. All four suppressors responded to GAG in addition to GAA but did not suppress the known mutant codons of several other trpA mutants. Other properties are discussed, along with possible reasons for our success in obtaining these suppressors.

Transurethral prostatectomy: analysis and comparison of four clinical series.

Charts of 302 patients from four groups who had transurethral prostatectomy were reviewed with respect to patient characteristics and complications. The four groups were similar in average age and amount of tissue resected. Patients from the University of Alabama Hospital and Veterans Administration Hospital tended to have more associated illnesses than patients in the two private practices. Bleeding, the most frequently seen intraoperative and immediate postoperative complication, occurred most often in the University of Alabama Hospital series and in patients with prostates weighing more than 45 gm. Incontinence, the most frequent long-term complication, occurred most often in patients from the Veterans Administration Hospital. Complications and characteristics are compared with those in previously reported series of patients having transurethral prostatectomy and with those of the American Urological Association cooperative study.

Staphylococcal osteomyelitis--a comparison of co-amoxiclav with clindamycin and flucloxacillin in an experimental rat model.

A rat model of Staphylococcus aureus osteomyelitis was used to compare treatment with co-amoxiclav, flucloxacillin and clindamycin. Co-amoxiclav (amoxycillin/clavulanic acid 200/50 mg/kg), flucloxacillin (200 mg/kg) and clindamycin (50 mg/kg) were injected subcutaneously tds for 28 days, commencing 14 days after infection. Eight days after cessation of treatment, high numbers of staphylococci were recovered from the infected tibiae of all control rats. All treatments, at clinically achievable concentrations, significantly (P < 0.05) reduced the bone bacterial titres. However, 50% of tibiae from co-amoxiclav-treated animals were sterile, compared with 17% and 25% from flucloxacillin- or clindamycin-treated animals respectively. Histopathological examination of tibiae reflected the bacteriological results, and showed that the severity of the osteomyelitis was greatly reduced in antibiotic-treated animals compared with non-treated controls. Twenty-eight days after cessation of therapy, bacterial counts from co-amoxiclav and clindamycin-treated animals remained significantly (P < 0.05) lower than those of non-treated controls, although the gross and microscopic appearance of clindamycin and flucloxacillin-treated tibiae suggested that recrudescence of the infection may have occurred. The results of this study demonstrated that co-amoxiclav was as effective as flucloxacillin and clindamycin in the treatment of an experimental chronic staphylococcal osteomyelitis.