Contrasting speed and accuracy approaches to measure executive functions in three low-and middle-income countries

Executive functions (EF) can be measured by tests assessing accuracy, reaction times and by computing scores which combine these two components. Interpretation issues can arise from the use of different scoring methods across studies. Given that EF measures and their scoring methods are predominantly developed and validated in high income countries, little is known about the generalisability of such methods cross- culturally. The current paper compares two different established scoring approaches for measures of inhibition and cognitive flexibility: difference scores (which utilise reaction time only) and computed scores (combining accuracy and reaction time). We utilised data collected in adulthood from three low- and middle-income birth cohorts (Guatemala, Philippines, South Africa). Non-normal distributions were observed for both scoring methods in all three samples; however, this was more pronounced for the difference score method. Differing distribution patterns were observed across the three cohorts, which was especially evident in the Guatemala cohort, highlighting potential issues with using these methods across diverse populations. The data suggest that the computed scores may be a reliable measure of EF. However, the different ways of scoring and interpreting EF instruments need to be considered carefully for each population before use.

Early-life stature, preschool cognitive development, schooling attainment, and cognitive functioning in adulthood: a prospective study in four birth cohorts

BACKGROUND

Nutrition is important for growth and brain development and therefore cognitive ability. Growth faltering in early childhood, an important indicator of early adversity, is associated with poorer developmental outcomes, some into adulthood, but this association probably reflects early-life deprivation. We aimed to investigate the associations between early-life stature, child IQ, and adult IQ.

METHODS

In this cohort study, we used prospective longitudinal data collected in four birth cohorts from Brazil (born in 1993), Guatemala (born in 1969-77), the Philippines (born in 1983-84), and South Africa (born in 1990). Using multivariable linear models, we estimated the relative contributions of early-life stature, child IQ, and schooling (highest school year completed) to adult IQ, including interaction effects among the early-childhood measures and schooling.

FINDINGS

We included 2614 individuals in the analysis. Early-life stature was associated with adult IQ (range across eight site-by-sex groups -0·14 to 3·17 IQ points) and schooling (-0·05 to 0·77 years) per height-for-age Z-score. These associations were attenuated when controlling for child IQ (-0·86 to 1·72 for adult IQ and -0·5 to 0·60 for schooling). The association of early-life stature with adult IQ was further attenuated when controlling for schooling (-1·86 to 1·21). Child IQ was associated with adult IQ (range 3·91 to 10·02 points) and schooling (0·25 to 1·30 years) per SD of child IQ in all groups; these associations were unattenuated by the addition of early-life stature to the models. The interaction between schooling and child IQ, but not that between schooling and early-life stature, was positively associated with adult IQ across groups.

INTERPRETATION

The observed associations of early-life stature with adult IQ and schooling varied across cohorts and sexes and explained little variance in adult IQ beyond that explained by child IQ. These findings suggest that interventions targeted at growth for health and early development are important. Our results are consistent with the inference that improving long-term cognitive outcomes might require interventions that more specifically target early cognitive ability.

FUNDING

Bill & Melinda Gates Foundation.

1187 Adapting Postgraduate Anatomy Education During The COVID-19 Pandemic

Aim

A solid understanding of anatomy and its application is crucial to the development of safe surgeons. Cadaveric dissection has traditionally been the gold standard for learning anatomy however the disruption of anatomy teaching from the COVID-19 pandemic has led to a shift in methods for teaching both undergraduate and postgraduate students. We sought to design, deliver and evaluate a virtual MRCS anatomy revision course for doctors led by anatomy demonstrators.

Method

A series of six high yield revision sessions on the anatomy of the abdomen and pelvis, upper limb, lower limb, thorax and head and neck were organised on a virtual platform. The course was advertised on social media targeting groups for doctors. These sessions were taught by a senior anatomy demonstrator and previous examiner for the MRCS. This was followed by a series of interactive single best answer questions. The answers were then discussed in a subsequent session facilitated by current junior anatomy demonstrators. Feedback on student satisfaction, relevance and content of each session was collated.

Results

Online feedback was completed by 263 students and was universally positive. Our results highlight the relevance of the sessions for doctors preparing for both MRCS part A and B examinations. Our aim is to develop this teaching series to create an environment where postgraduate learners feel supported and can build on pre-existing knowledge.

Conclusions

Virtual anatomy teaching can be a sustainable method of supporting the learning process of doctors preparing for surgical examinations, complementing independent study, virtual dissection and hands on cadaveric dissection.

Cognitive and socio-emotional correlates of psychological well-being and mental health in Guatemalan adults

BACKGROUND

Little is known about associations of psychological and mental well-being with cognitive and socioemotional factors in low and middle-income countries, particularly among vulnerable populations born in adverse environments that may restrict developmental potential. This study aimed to examine the cognitive and socioemotional correlates of psychological well-being and mental health in a cohort of Guatemalan adults born in contexts of poverty and malnutrition.

METHODS

From Dec 2017 to Apr 2019, data were collected from 704 women and 564 men ages 40-57 years living in four rural villages in eastern Guatemala and Guatemala City. We measured latent domains of psychological well-being, spirituality and religion, emotional support, and executive function using Confirmatory Factor Analysis (CFA). Under a Structural Equation Modeling framework, we examined intercorrelations among latent domains and observed measures of intelligence and mental health.

RESULTS

CFA supported the construct validity of factor structures in this population. Correlations of psychological well-being with spirituality and religion were moderate in women (r = 0.68, p < 0.001) and men (r = 0.70, p < 0.001). Executive function was weakly correlated with psychological well-being in men (r = 0.23, p < 0.001) and showed no association in women. Correlations of psychological well-being with emotional support and IQ were weak in women (r = 0.34, and r = 0.15, respectively; p < 0.001 for both) and men (r = 0.35, and r = 0.25, respectively; p < 0.001 for both). Mental health and IQ were weakly correlated in men (r = 0.09, p < 0.05) and showed no association in women. Mental health showed weak correlations with emotional support (r = 0.18, p < 0.001 in women; r = 0.09, p < 0.05 in men), psychological well-being (r = 0.32 and r = 0.35, in women and men respectively; p < 0.001 for both) and showed no association with executive function in both sexes.

CONCLUSIONS

Of all examined factors, spirituality and religion made the greatest contribution to psychological well-being. These findings support the notion that in populations experiencing difficult circumstances, religion can perhaps make a greater contribution to well-being and aid coping. More research is needed to examine mediators of this association.

Executive functions form a single construct and are associated with schooling: Evidence from three low- and middle- income countries

Measuring executive function (EF) among adults is important, as the cognitive processes involved in EF are critical to academic achievement, job success and mental health. Current evidence on measurement and structure of EF largely come from Western, Educated, Industrialized, Rich and Democratic (WEIRD) countries. However, measuring EF in low-and-middle-income countries (LMICs) is challenging, because of the dearth of EF measures validated across LMICs, particularly measures that do not require extensive training, expensive equipment, or professional administration. This paper uses data from three LMIC cohorts to test the feasibility, validity and reliability of EF assessment in adults using three sub-tests (representing key components of EF) of the NIH Toolbox Cognitive battery. For each cohort, all three EF measures (inhibition, flexibility and working memory) loaded well onto a unidimensional latent factor of EF. Factor scores related well to measures of fluid intelligence, processing speed and schooling. All measures showed good test-retest reliability across countries. This study provides evidence for a set of sound measures of EF that could be used across different cultural, language and socio-economic backgrounds in future LMIC research. Furthermore, our findings extend conclusions on the structure of EF beyond those drawn from WEIRD countries.

Results of the feasibility phase of the managed activity graded exercise in teenagers and pre-adolescents (MAGENTA) randomised controlled trial of treatments for chronic fatigue syndrome/myalgic encephalomyelitis

BACKGROUND

Chronic fatigue syndrome (CFS) also known as myalgic encephalomyelitis (ME) is relatively common in young people and causes significant disability. Graded exercise therapy (GET) and activity management are recommended by the National Institute for Health and Care Excellence (NICE) despite a limited evidence-base for either treatment in paediatric CFS/ME. This paper reports on feasibility and acceptability measures from the feasibility phase of the ongoing MAGENTA randomised controlled trial (RCT) investigating GET versus activity management for young people with CFS/ME.

METHODS

Setting: Three specialist secondary care National Health Service (NHS) Paediatric CFS/ME services (Bath, Cambridge and Newcastle).Participants: Young people aged 8-17 years with a diagnosis of mild to moderate CFS/ME. Young people were excluded if they were severely affected, referred to cognitive behavioural therapy (CBT) at initial assessment or unable to attend clinical sessions.Interventions: GET and activity management delivered by physiotherapists, occupational therapists, nurses and psychologists. Families and clinicians decided the number (typically 8-12) and frequency of appointments (typically every 2-6 weeks).Outcome Measures: Recruitment and follow-up statistics. We used integrated qualitative methodology to explore the feasibility and acceptability of the trial processes and the interventions.

RESULTS

80/161 (49.7%) of eligible young people were recruited at two sites between September 2015 and August 2016, indicating recruitment to the trial was feasible. Most recruitment (78/80; 97.5%) took place at one centre. Recruitment consultations, online consent and interventions were acceptable, with less than 10% in each arm discontinuing trial treatment. Response rate to the primary outcome (the SF36-PFS at 6 months) was 91.4%. Recruitment, treatment and data collection were not feasible at one centre. The site was withdrawn from the study.In response to data collected, we optimised trial processes including using Skype for recruitment discussions; adapting recruiter training to improve recruitment discussions; amending the accelerometer information leaflets; shortening the resource use questionnaires; and offering interventions via Skype. These amendments have been incorporated into the full trial protocol.

CONCLUSIONS

Conducting an RCT investigating GET versus activity management is feasible and acceptable for young people with CFS/ME.

TRIAL REGISTRATION

ISRCTN23962803 10.1186/ISRCTN23962803, date of registration: 03 September 2015.

Treatment preference and recruitment to pediatric RCTs: A systematic review

BACKGROUND

Recruitment to pediatric randomised controlled trials (RCTs) can be a challenge, with ethical issues surrounding assent and consent. Pediatric RCTs frequently recruit from a smaller pool of patients making adequate recruitment difficult. One factor which influences recruitment and retention in pediatric trials is patient and parent preferences for treatment.

PURPOSE

To systematically review pediatric RCTs reporting treatment preference.

METHODS

Database searches included: MEDLINE, CINAHL, EMBASE, and COCHRANE.Qualitative or quantitative papers were eligible if they reported: pediatric population, (0-17 years) recruited to an RCT and reported treatment preference for all or some of the participants/parents in any clinical area. Data extraction included: Number of eligible participants consenting to randomisation arms, number of eligible patients not randomised because of treatment preference, and any further information reported on preferences (e.g., if parent preference was different from child).

RESULTS

Fifty-two studies were included. The number of eligible families declining participation in an RCT because of preference for treatment varied widely (between 2 and 70%) in feasibility, conventional and preference trial designs. Some families consented to trial involvement despite having preferences for a specific treatment. Data relating to 'participant flow and recruitment' was not always reported consistently, therefore numbers who were lost to follow-up or withdrew due to preference could not be extracted.

CONCLUSIONS

Families often have treatment preferences which may affect trial recruitment. Whilst children appear to hold treatment preferences, this is rarely reported. Further investigation is needed to understand the reasons for preference and the impact preference has on RCT recruitment, retention and outcome.

How do parents of school-aged children respond to their children's extending gestures?

Gesture plays an important role in early language development, as how parents respond to their children's gestures may help to facilitate language acquisition. Less is known about whether parental responses facilitate language learning later in childhood and whether responses vary depending on children's language ability. This study explored parental responses to extending gestures in a sample of school-aged children (aged six to eight years) with developmental language disorder, low-language and educational concerns, and typically developing children. Overall there were no group differences in the types of responses parents provided to extending gestures. Parents predominantly responded with positive feedback but also displayed moderate proportions of verbal translations and clarification requests. Within the DLD group, the proportion of parent translations was negatively associated with language ability. Our finding suggests that parent responses serve to enhance communication and engage children in tasks, but there is limited evidence that they support new language learning at this age.

Gesture Production in Language Impairment: It's Quality, Not Quantity, That Matters

PURPOSE

The aim of this study was to determine whether children with language impairment (LI) use gesture to compensate for their language difficulties.

METHOD

The present study investigated gesture accuracy and frequency in children with LI (n = 21) across gesture imitation, gesture elicitation, spontaneous narrative, and interactive problem-solving tasks, relative to typically developing (TD) peers (n = 18) and peers with low language and educational concerns (n = 21).

RESULTS

Children with LI showed weaknesses in gesture accuracy (imitation and gesture elicitation) in comparison to TD peers, but no differences in gesture rate. Children with low language only showed weaknesses in gesture imitation and used significantly more gestures than TD peers during parent-child interaction. Across the whole sample, motor abilities were significantly related to gesture accuracy but not gesture rate. In addition, children with LI produced proportionately more extending gestures, suggesting that they may use gesture to replace words that they are unable to articulate verbally.

CONCLUSION

The results support the notion that gesture and language form a tightly linked communication system in which gesture deficits are seen alongside difficulties with spoken communication. Furthermore, it is the quality, not quantity of gestures that distinguish children with LI from typical peers.

The impact of nonverbal ability on prevalence and clinical presentation of language disorder: evidence from a population study

BACKGROUND

Diagnosis of 'specific' language impairment traditionally required nonverbal IQ to be within normal limits, often resulting in restricted access to clinical services for children with lower NVIQ. Changes to DSM-5 criteria for language disorder removed this NVIQ requirement. This study sought to delineate the impact of varying NVIQ criteria on prevalence, clinical presentation and functional impact of language disorder in the first UK population study of language impairment at school entry.

METHODS

A population-based survey design with sample weighting procedures was used to estimate population prevalence. We surveyed state-maintained reception classrooms (n = 161 or 61% of eligible schools) in Surrey, England. From a total population of 12,398 children (ages 4-5 years), 7,267 (59%) were screened. A stratified subsample (n = 529) received comprehensive assessment of language, NVIQ, social, emotional and behavioural problems, and academic attainment.

RESULTS

The total population prevalence estimate of language disorder was 9.92% (95% CI 7.38, 13.20). The prevalence of language disorder of unknown origin was estimated to be 7.58% (95% CI 5.33, 10.66), while the prevalence of language impairment associated with intellectual disability and/or existing medical diagnosis was 2.34% (95% CI 1.40, 3.91). Children with language disorder displayed elevated symptoms of social, emotional and behavioural problems relative to peers, F(1, 466) = 7.88, p = .05, and 88% did not make expected academic progress. There were no differences between those with average and low-average NVIQ scores in severity of language deficit, social, emotional and behavioural problems, or educational attainment. In contrast, children with language impairments associated with known medical diagnosis and/or intellectual disability displayed more severe deficits on multiple measures.

CONCLUSIONS

At school entry, approximately two children in every class of 30 pupils will experience language disorder severe enough to hinder academic progress. Access to specialist clinical services should not depend on NVIQ.

Gestural abilities of children with specific language impairment

BACKGROUND

Specific language impairment (SLI) is diagnosed when language is significantly below chronological age expectations in the absence of other developmental disorders, sensory impairments or global developmental delays. It has been suggested that gesture may enhance communication in children with SLI by providing an alternative means to convey words or extend utterances. However, gesture is a complex task that requires the integration of social, cognitive and motor skills, skills that some children with SLI may find challenging. In addition, there is reason to believe that language and gesture form an integrated system leading to the prediction that children with a SLI may also have difficulties with gestural communication.

AIMS

To explore the link between language and gesture in children with poor language skills.

METHODS & PROCEDURE

Fifteen children with SLI and 14 age-matched typically developing children (TD) participated in this study. The children completed measures of expressive and receptive vocabulary, non-verbal cognition, motor control, gesture comprehension and gesture production.

OUTCOMES & RESULTS

TD children achieved significantly higher scores on measures of gesture production and gesture comprehension relative to children with SLI. Significant correlations between both measures of vocabulary and both measures of gesture suggest a tight link between language and gesture.

CONCLUSIONS & IMPLICATIONS

The findings support the idea that gesture and language form one integrated communication system, rather than two separate communication modalities. This implies that children with SLI may have underlying deficits that impact not only on language but also on gesture production and comprehension.

Liver transplantation outcome in patients with angiographically proven coronary artery disease: a multi-institutional study

Over the last decade the age of liver transplant (LT) recipients and the likelihood of coronary artery disease (CAD) in this population have increased. There are no multicenter studies that have examined the impact of CAD on LT outcomes. In this historical cohort study, we identified adult LT recipients who underwent angiography prior to transplantation at seven institutions over a 12-year period. For each patient we recorded demographic data, recipient and donor risk factors, duration of follow-up, the presence of angiographically proven obstructive CAD (≥50% stenosis) and post-LT survival. Obstructive CAD was present in 151 of 630 patients, the CAD(+) group. Nonobstructive CAD was found in 479 patients, the CAD(-) group. Patient survival was similar for the CAD(+) group (adjusted HR 1.13, CI = [0.79, 1.62], p = 0.493) compared to the CAD(-) group. The CAD(+) patients were further stratified into severe (CADsev, >70% stenosis, n = 96), and moderate CAD (CADmod, 50-70% stenosis, n = 55) groups. Survival for the CADsev (adjusted HR = 1.26, CI = [0.83, 1.91], p = 0.277) and CADmod (adjusted HR = 0.93, CI = [0.52, 1.66], p = 0.797) groups were similar to the CAD(-) group. We conclude that when current CAD treatment strategies are employed prior to transplant, post-LT survival is not significantly different between patients with and without obstructive CAD.

Protection from experimental ventilator-induced acute lung injury by IL-1 receptor blockade

Background: Clinical studies have shown that injurious mechanical ventilation is associated with elevated airspace and plasma levels of interleukin-1β (IL-1β); however, the potential therapeutic value of IL-1 inhibition in acute lung injury has not been thoroughly investigated.

A study was undertaken to determine if IL-1 signaling is a necessary early event in the pathogenesis of experimental ventilator-induced lung injury (VILI).

Methods: Mice deficient in IL-1 receptor type 1 (IL1R1) and rats treated with IL-1 receptor antagonist (IL-1Ra) were mechanically ventilated with high tidal volume (30 ml/kg) and the effect of IL-1 signaling blockade on lung injury severity was determined.

Results: Permeability as measured by radiolabeled albumin flux was significantly lower in IL1R1 null mice compared with wild type mice during injurious ventilation (P<0.05). IL-1Ra significantly decreased protein permeability and pulmonary oedema in rats during injurious ventilation. IL-1Ra also decreased airspace and plasma levels of the chemokine CXCL1 and airspace neutrophils. IL-1Ra decreased expression of NOS2 and ICAM-1 mRNA in whole lung. Bronchoalveolar lavage fluid levels of RTI40, a marker of type I cell injury, were 2.5 times lower in following IL-1Ra treatment (P < 0.05). In isolated type II pneumocytes, IL-1β reduced electrical resistance and increased transepithelial permeability.

Conclusions: IL-1 contributes to alveolar barrier dysfunction in VILI by promoting lung neutrophil recruitment, and by increasing epithelial injury and permeability. Because preserved alveolar barrier function is associated with better outcomes in patients with acute lung injury, these data support further testing of IL-1Ra for the treatment of acute lung injury.

Antimicrobial resistance in Salmonella isolated from animals and their environment in England and Wales from 1988 to 1999

Resistance to 16 antimicrobial agents was monitored in 109,125 Salmonella cultures isolated from animals, their environment and feedstuffs between 1988 and 1999. The sensitivity of the 6512 isolates of Salmonella enterica enterica serotype Dublin to all the antimicrobial agents tested varied from 98.2 per cent in 1997 to 99.7 per cent in 1990 and 1996. In contrast, among 28,053 isolates of Salmonella enterica enterica serotype Typhimurium, there was a marked decrease in their sensitivity to all the antimicrobial agents tested, from 57.4 per cent in 1992 to 7.6 per cent in 1995, owing to the widespread occurrence in farm animals of S Typhimurium isolates of the definitive type DT104, resistant to ampicillin, sulphonamides, streptomycin, chloramphenicol and tetracyclines, although the percentage of sensitive isolates increased to 18.4 per cent in 1999, when the incidence of DT104 had decreased. Some isolates of DT104 also showed an increase in resistance to potentiated sulphonamides (2.4 per cent in 1989 to 19.2 per cent in 1999) and nalidixic acid (0 per cent in 1992, 3.8 per cent in 1995 to a peak of 16.9 per cent in 1998). In 1996, 5.1 per cent of 1086 isolates of S Typhimurium from cattle and 35.9 per cent of 192 isolates of S Typhimurium from poultry showed resistance to nalidixic acid. Of the other 74,528 Salmonella isolates, the percentage of strains sensitive to all the antimicrobials tested decreased slightly from 88.2 per cent in 1988 to 70.6 per cent in 1996 and then increased slightly to 73.7 per cent in 1999. The commonest of these other Salmonella serotypes was Salmonella Enteritidis (20,982), which remained predominantly susceptible (ranging from 81.4 to 97.4 per cent) during the study period. Few isolates were resistant to commonly used veterinary antimicrobials, for example, furazolidone, the use of which was banned in 1990, and the aminoglycoside, apramycin.

Epidemiology and characterization of animal Salmonella enterica subspecies Enterica serotype typhimurium DT104 in Hungary

Reports on the internationally emerging significance of multiresistant zoonotic Salmonella in animals and man prompted studies to estimate the significance of multiresistant Salmonella enterica subspecies enterica serotype Typhimurium (S. Typhimurium) phage type DT104 of animal origin in Hungary. A collection of 231 strains (primarily of goose, turkey, poultry and porcine origin from the years 1997-1998) was tested for resistance against 7 selected antibiotics (ampicillin, chloramphenicol, enrofloxacin, nalidixic acid, streptomycin, tetracycline and sulphamethoxazole). Strains with resistance against 3 or more were defined as multiresistant. All strains were phage typed using Felix-Callow's S. Typhimurium phage typing system, and 91 of them (suspect DT104) were also typed according to Anderson's definitive typing (DT) system. In this study, 14% of animal strains from 1997-1998 was classified as DT104, for which turkey, pig and duck seemed to be the main carriers, and the multiresistant non-DT104 strains represented a further 6% of this collection. The prevalence of DT104 was highest among strains of turkey origin (50%), followed by strains of pig (29%), chicken (25%), duck (19%), and goose (3%) origin. The other DT104 related phage types (DT12 and U302) were only detected in the case of 4 strains (2 of porcine, and one each of turkey and of goose origin). The DT104 corresponded to the Felix-Callow types 2/3 or 2c/3 in each case, except in the case of 3 turkey strains where they corresponded to type 35/3. Nalidixic acid resistance was detected in all multiresistant turkey strains and in some of other animal origin but none of these strains were resistant to enrofloxacin. A retrospective analysis (based on the above relationship) indicated that S. Typhimurium strains corresponding to DT104 could be present and increase in the Hungarian farm animal population from about 2% to 20% between 1985 and 1990, in a manner similar to the emergence of human DT104, as reported elsewhere (Pászti et al., 2000). The 91 suspect DT104 strains were also tested for plasmid profile and for spvC gene indicating the presence of the large serotype specific plasmid (Ssp). No characteristic plasmid profile could be attributed to S. Typhimurium DT104. The serovar-specific large plasmid was detected by PCR for spvC in 100% of DT104 strains and in 77% of the non-DT104 strains. The virulence of two DT104 strains was tested in orally infected day-old chicks and compared with virulence of 4 non-DT104 strains. Higher colonizing virulence of DT104 strains could be established as compared to the other strains.

The transcription factors NF-kappab and AP-1 are differentially regulated in skeletal muscle during sepsis

Sepsis is associated with increased muscle proteolysis and upregulated transcription of several genes in the ubiquitin-proteasome proteolytic pathway. Glucocorticoids are the most important mediator of sepsis-induced muscle cachexia. Here, we examined the influence of sepsis in rats on the transcription factors NF-kappaB and AP-1 in skeletal muscle and the potential role of glucocorticoids in the regulation of these transcription factors. Sepsis was induced by cecal ligation and puncture (CLP). Control rats were sham-operated. NF-kappaB and AP-1 DNA binding activity was determined by electrophoretic mobility shift assay (EMSA) in extensor digitorum longus muscles at different time points up to 16 h after sham-operation or CLP. Sepsis resulted in an early (4 h) upregulation of NF-kappaB activity followed by inhibited NF-kappaB activity at 16 h. AP-1 binding activity was increased at all time points studied during the septic course. When rats were treated with the glucocorticoid receptor antagonist RU38486, NF-kappaB activity increased, whereas AP-1 activity was not influenced by RU38486. The results suggest that NF-kappaB and AP-1 are differentially regulated in skeletal muscle during sepsis and that glucocorticoids may regulate some but not all transcription factors in septic muscle.

Natural and experimental infection of normal cattle with Escherichia coli O157

The objective of the study was to determine the effects of inoculating cattle orally with a strain of Escherichia coli O157:H7 (A84/92). However, before they were challenged two of the six calves were found to be infected naturally with a wild-type strain of E coli O157 and two more of them became infected later. The number of daily faeces samples from which the wild-type E coli O157 was isolated ranged from one to 10. After they were inoculated, A84/92 was detected in all the calves' faeces on one to six of the next 14 days, and later from the faeces samples of three calves on two, three, and 11 occasions, the last occasion being between 19 and 51 days after inoculation. Two calves were redosed with A84/92, and the organism was isolated on a further five and 15 occasions, the last being after 20 and 58 days. In three dry cows, A84/92 was isolated from the faeces on three to 11 of the 14 days after they were inoculated. Two of the cows were redosed and from one of them it was isolated on 15 occasions, the last being 44 days after the initial infection; in the other cow no further isolation was made. In three lactating cows, it was detected on three to four of the 14 days after they were inoculated, and similar results were obtained after they were reinoculated. None of the animals showed clinical signs and no lesions were detected in the intestines of the calves. Three calves had a serological response to E coli O157 but, with the exception of one cow which had a slight increase to IgM levels, no serological changes were observed in the adult cattle.

Antibiotic resistance monitoring in bacteria of animal origin: analysis of national monitoring programmes

Methods of antibiotic resistance monitoring of bacteria from animals in 12 European countries were surveyed in 1998. Most laboratories used disk diffusion methods, usually expressing results qualitatively, although a few also expressed the results either as MICs or zone diameters. The number of antibiotics used ranged from 5 to 37 (mean 15) and the most common antibacterials were streptomycin, gentamicin, neomycin, ampicillin, tetracyclines, chloramphenicol and sulphonamides. Salmonellae were monitored by most centres but few-tested campylobacter regularly. Escherichia coli from a wide range of animal species were tested in nine countries. Enterococci were tested on a limited ad hoc basis in six countries. Staphylococci, streptococci and pasteurellae were also frequently monitored but the number of isolates tested showed wide variation. Overall the presentation of the results differed, but most programmes used disk diffusion, control strains and monitored similar bacteria. Thus, it may be possible to harmonise monitoring programmes within the EU.

Transmission of Vero cytotoxin producing Escherichia coli O157 infection from farm animals to humans in Cornwall and west Devon

A study of Vero cytotoxin producing Escherichia coli (VTEC) O157 infections in Cornwall and West Devon was conducted to identify associations between human infection and contact with farm animals. In three years from November 1994 to October 1997, 63,000 stool specimens were submitted to four participating microbiology laboratories and screened for E. coli O157. Sixty-nine confirmed cases were interviewed to assess the extent of any direct or indirect contact with farm animals. Nine out of 22 investigations conducted on farms--in which animal rectal swabs, faecal specimens, fore-stream milk samples (first draw-off from teats), and various environmental samples were tested--yielded VTEC O157. In seven incidents one or more isolates from animals were indistinguishable from the isolate(s) from the human case(s) using phenotypic and genotypic subtyping. Cases associated with animal contact included farm visitors, holidaymakers, and members of farming families and farm workers.

Monoclonal antibodies recognising fimbriae F107 (F18) of an oedema disease causing strain of Escherichia coli

Escherichia coli isolated from experimentally induced oedema disease in pigs was used for the isolation and purification of F107 fimbriae. The reference strain was probed using membrane DNA hybridisation for the presence of fed A gene. F107 fimbriae were purified on FPLC and purity was checked on HPLC and SDS PAGE. A protein with major subunit of 18.9 kDa was used for Mabs preparation. Mabs reacted with 18.9 kDa protein previously classified as a major fimbrial subunit and were able to detect F107 fimbriae in immunoelectron microscopy on the surface of the strains 107/86 and 8872. Other strains used in this study did not express any fimbriae. Western blot analysis and F107 ELISA confirmed, that Mabs react with 18.9 kDa subunit whereas strains passaged many times in laboratory did not express F107 fimbriae.

Infection of gnotobiotic calves with Escherichia coli o157:h7 strain A84

Six colostrum-deprived, hysterotomy-derived calves were maintained under sterile conditions and fed a milk replacer diet. At five days of age, five of the calves were dosed orally with 10(9) cfu of Escherichia coli O157:H7 strain A84. They were killed after, one, two, six, 12 and 24 days, and samples were taken for bacteriological and pathological examination. The sixth uninfected control calf was killed at seven days of age and matched samples were taken for pathological comparison. The animals remained normal throughout the observation period. Bacteriological data indicated a heavy bacterial load of strain A84 throughout the gastrointestinal tract but the bacterium was not found in liver, kidney or muscle. No evidence of 'attaching and effacing' lesions in the small or large intestine was found although there was a mild inflammatory response in the intestinal tract, consisting mainly of infiltrating eosinophils.

Uterine bacterial flora and uterine lesions in bitches with cystic endometrial hyperplasia (pyometra)

Thirty-eight complete genital tracts were obtained fresh from local veterinary practices after bitches had been ovariohysterectomised for the treatment of cystic endometrial hyperplasia (pyometra). The aerobic and anaerobic culture of swabs obtained aseptically from the uterine lumen demonstrated the presence of Escherichia coli in 28 of the 29 cases from which bacteria were isolated and, from 25, a pure culture was obtained. Sixteen different serotypes were identified from 24 genital tracts; 032K+ CNF+ was isolated from four of 16 cases and 04K-; from three of 16 cases. Cytotoxin necrotising factors (CNFs) were identified in seven of the 16 serotypes; they included 02, 04, 06, 022, 025, 045 and 075, which except for 06 and 045 were haemolytic. Strains 04K- and 07K+ completely destroyed the integrity of the endometrial epithelium whereas 088K+ and 088K- had the least effect. The scores for the reduction in the integrity of the endometrial epithelium and the degree of infiltration of inflammatory cells were greater in the presence of CNF 1.

The epidemiology of Salmonella typhimurium in cattle: plasmid profile analysis of definitive phage type (DT) 204c

During the period 1979-1991, Salmonella Typhimurium DT 204c was the cause of a major epidemic of salmonellosis in calves in the UK. Plasmid profile analysis of DT 204c isolates from England and Wales commenced in 1986 and isolates from all subsequent incidents were examined by this technique. Forty-three different plasmid profile types (PPTs) were detected, of which the commonest, designated type E, constituted 44.6-80.2% of the annual incidents during the study period. Some PPTs, e.g., F and P, were detected throughout most years of the study, whereas PPTs O and 6 persisted for short periods. Until 1984, most isolates were resistant to neomycin, but the subsequent predominant PP type E was sensitive to this antibacterial agent. It was concluded that during the epidemic there was an evolution of new genotypes, of which only some persisted; again, antibacterial resistance genes may be acquired or lost. The study demonstrated the value of PP typing for epidemiological studies.

Studies of the presence of verocytotoxic Escherichia coli O157 in bovine faeces submitted for diagnostic purposes in England and Wales and on beef carcases in abattoirs in the United Kingdom

A survey of beef carcases in abattoirs in the UK was carried out in order to estimate the prevalence of contamination with verocytotoxin-producing Escherichia coli (VTEC) serogroup O157. Contamination with verocytotoxin-producing E. coli (VTEC) O157 was confirmed in 0.47% of the 4067 (95% confidence limits 0.22-1.00%) of neck muscle samples. A significant tendency for carcases present in the same abattoir on the same day to have similar results was found, thus suggesting cross contamination. VTEC O157 was found in 0.83% of 6495 bovine faeces samples routinely submitted for diagnostic purposes to Veterinary Investigation Centres in England and Wales. Of the samples from cattle less than 6 months old, 3.7% of 68 samples from animals without gastrointestinal disease were positive for E. coli O157, in contrast to 0.75% of 2321 samples from cases of gastrointestinal disease. No association with season or herd type (beef or dairy) was found.

Bacteriological and serological investigation of persistent Salmonella enteritidis infection in an integrated poultry organisation

Bacteriological monitoring of broiler breeder farms, the hatchery, rendering plant and animal feed mill during 1991 identified a number of potential cross-contamination hazards, such as the use of processed poultry proteins in the company feed mill and contamination of egg trolleys and trays, which may have led to widespread dissemination of Salmonella enteritidis within an integrated poultry organisation. Serological monitoring of the flocks suggested that, in most cases, substantial exposure to S. enteritidis infection occurred during the mid-rearing stage whereas routine bacteriological monitoring of poultry house litter and dust samples, and meconium samples taken in the hatchery identified infection only after the onset of the laying period. At least 10 phage types and six plasmid profile types of S. enteritidis were identified in historic submissions from the organisation including one apparently specific plasmid profile type that was distributed throughout the various parts of the company. During sampling for this investigation, most of these strains were not identified, and the number of plasmid profile types was reduced to a single common UK type.

Use of antibody-coated cellulose sponges for enhanced isolation of salmonella

One thousand, four hundred and fifty-one naturally contaminated samples from pig, poultry and cattle farms, poultry hatcheries and animal feed mills were examined in a trial in which transfer of small portions of cellulose sponge coated with salmonella somatic polyvalent antiserum was compared with transfer of standard liquid inocula from pre-enrichment to selective enrichment culture. Salmonella was found in 281 (19.4%) of the samples using the standard method, compared with 385 (26.5%) using the sponge method. It was therefore concluded that antibody-coated cellulose sponges could be a simple means of increasing the recovery of salmonellas from pre-enrichment broths and thereby enhancing the test sensitivity.

Distribution of Salmonella contamination in ten animal feedmills

Detailed sampling of spillage and dust from milling equipment was carried out in nine animal feedmills, three of which were sampled twice. The salmonella isolation rate ranged from 1.1% to 41.7% of the samples and the most contaminated mills were those where the inside of the cooling systems for pellet or mash had been colonised by salmonella. A wide range of salmonella serotypes were isolated which included Salmonella typhimurium and S. enteritidis. Limited sampling every two weeks for an 18-month period in another animal feedmill showed marked variation in the contamination rate of samples and range of salmonella serotypes found. Contamination of ingredient intake pits and outloading gantries for finished products by wild bird droppings containing salmonella was also found in four mills.

Immunomagnetic separation for enhanced flagellar antigen phase inversion in salmonella

Immunomagnetic separation (IMS) was used to reduce delays in serotyping caused by slow flagellar phase inversion of diphasic salmonellas. Some 375 strains of 11 salmonella serotypes were examined using IMS. The mean time for successful flagellar phase inversion was reduced from 4.3 (range 1-18) d to 1.0 (range 1-3) d using the IMS method, and in a further experiment phase inversion was achieved within 8 h in 112 of a further 117 strains representing four salmonella serotypes.

Studies on the development and use of a monoclonal sandwich ELISA for the detection of verotoxic Escherichia coli in animal faeces

A sandwich ELISA using monoclonal antibodies to Escherichia coli verocytotoxins 1 and 2 for capture and detection was developed for detection of verocytotoxin-producing Escherichia coli (VTEC) in animal faeces. For optimal toxin detection, the faeces were cultured in MacConkey broth before subculture on to trypticase soy agar containing mitomycin C. It was possible to detect between 10 and 10(3) VTI-producing and 1 to 10 VT2-producing E coli/g faeces, and overall the sensitivity and specificity of the ELISA for VTEC in faeces were 80.5 per cent and 91.2 per cent, respectively, when compared with a verocell assay. A limited survey of faeces from healthy animals (89 cattle, 16 sheep, 22 pigs, 11 goats and six domestic fowl) and faeces from 144 cattle with enteric disease detected VTEC in 64 per cent, 63 per cent, 5 per cent, 45 per cent, none and 16 per cent of the samples, respectively.

Attaching and effacing E. coli. Microscopic and ultrastructural observation of intestinal infections in pigs

Pigs aged from neonate to 8 weeks with naturally occurring diarrhoea were submitted to a Veterinary Investigation Centre for routine diagnosis. They were retrospectively found to be infected with "attaching and effacing" E. coli (AEEC) on histological and ultrastructural examination of the intestinal tract. Subcultures of E. coli isolated from some of the affected pigs were tested against standard anti-sera and probed for the presence of verotoxin (VT) and "cae" genes. One strain of E. coli was positive for the VT gene and three VT-negative strains possessed the "cae" gene. This preliminary report suggests that in naturally occurring diarrhoea of suckling and weaned pigs, AEEC infection can be identified by histological examination of the intestinal mucosa and confirmed by electron microscopy, in the abscence of infection by recognised enteric pathogens on microbiological examination.

World Health Organisation--supervised interlaboratory comparison of ELISAs for the serological detection of Salmonella enterica serotype Enteritidis in chickens

A collaborative exercise, supervised by the World Health Organisation, was set up to compare ELISAs used for the serological detection of Salmonella enteritica serotype Enteritidis in chickens. The aim was to ascertain how far agreement could be reached on the interpretation of optical density readings for high titre, intermediate titre and low titre sera. Two sets of sera were sent to 14 participants. The first set compared high, medium and low titre sera raised in specified-pathogen-free and commercial broiler breeder chickens. The second set comprised 20 sera of different antibody titres raised in commercial birds reared under laboratory conditions and sent blind. Both indirect and double-antibody sandwich blocking ELISAs were used with a number of different detecting antigens. With a few exceptions good agreement was reached on the interpretation of results obtained from high and low titre sera from the optical density obtained with a single serum dilution. Differences were observed in the interpretation of medium titre sera. The results suggested that most ELISAs produce reasonably comparable results and that practical problems may arise from interpretation of the results mainly as a result of the choice of the criteria used for differentiating sera obtained from infected and uninfected chickens. These problems are discussed.

Persistence of Salmonella enteritidis in poultry units and poultry food

1. Studies on the survival of Salmonella enteritidis in poultry units and food were carried out over a two-year period. 2. The organism persisted for at least one year in an empty trial house at the laboratory in which naturally-infected broiler breeder birds had previously been housed. A similar survival period was seen in a building which had housed an infected layer breeder flock, although infection was not detected in a subsequent pullet flock. 3. Salmonella enteritidis was also frequently found surviving outside poultry houses in small pockets of litter and fan dust which had been left after cleansing and disinfection of the site. On some poultry units S. enteritidis was also found in wild bird droppings. 4. Salmonella contamination appeared to persist preferentially in association with dust particles swept from the floor and in food troughs and S. enteritidis survived at least 26 months in artificially contaminated poultry food.

Studies of contamination of three broiler breeder houses with Salmonella enteritidis before and after cleansing and disinfection

Three broiler breeder houses on three different sites were sampled before and after cleansing and disinfection. None of the farms achieved total elimination of Salmonella enteritidis from the poultry house environment but substantial improvements were seen when errors in the cleansing and disinfection protocol in the first house had been corrected. Fundamental errors such as over-dilution and inconsistent application of disinfectants were observed despite supervision of the process by technical advisors. In each of the three poultry units failure to eliminate a mouse population that was infected with S. enteritidis was likely to be the most important hazard for the next flock.

Determination of an effective sampling regime to detect salmonella enteritidis in the environment of poultry units

A study of the dissemination of Salmonella enteritidis in the poultry breeder industry in the UK showed that the choice of sites for sampling the environment of occupied houses and empty houses which had been disinfected after depopulation had a significant influence on the outcome. Increased isolation rates could be achieved by sampling nest box floors and dust in open slave feed hoppers in occupied poultry houses. Nest box floors were the most sensitive sites for detection of residual environmental contamination in poultry houses where enrofloxacin treatment had been used. Floor sweepings, nest box floors, slave feed hoppers, hydrated wall fabric junctions and high beams and pipes were the most sensitive sample sites in cleansed and disinfected poultry houses. The use of universal disinfectant neutralisers gave good results in laboratory trials but appeared to reduce the isolation rate from field samples.

Seasonal variations in the isolation of Salmonella typhimurium, Salmonella enteritidis, Bacillus cereus and Clostridium perfringens from environmental samples

Calf carcasses contaminated with S. typhimurium, B. cereus and Cl. Perfringens were placed in either a decomposition pit or in a deep burial pit. Salmonella was isolated from the soil around the decomposition pit for 27 weeks and for 15 weeks around the burial site. Salmonella re-appeared in soil samples during cold winter weather after an apparent 9-week absence from the decomposition pit and after 68 weeks in the burial site (a total of 88 weeks after the start of the experiment). There was also an annual rise in the isolation rate of B. cereus from the soil during the colder winter months, but Cl. perfringens appeared to be more prevalent in samples taken during spring of the second year of the study. A similar apparent rise in the prevalence of S. enteritidis during a cold winter period occurred in an empty poultry house that had previously held a naturally infected broiler-breeder flock.