Early Diagnosis and Treatment of Cerebral Palsy in Children with a History of Preterm Birth

Infants born preterm are at increased risk of cerebral palsy (CP), with the risk increasing with decreasing gestational age. Although preterm children are at increased risk of CP compared with their term-born peers, most preterm children do not have CP and thus, it is important to have a standardized process for detecting those children at high risk of CP early. A combination of clinical history, neuroimaging, and physical examination is recommended to ensure early, accurate diagnosis. Early detection of CP is essential for timely early intervention to optimize outcomes for children and their families.

NICU Graduates: The Role of the Allied Health Team in Follow-Up

Infants who graduate from the neonatal intensive care unit, including those infants born preterm and/or with brain injury, are at increased risk of long-term neurodevelopmental impairments. The developmental allied health team, consisting of physical therapy, occupational therapy, and speech pathology, is crucial in early evaluation of gross motor, fine motor, feeding, and language development. Surveillance of neurodevelopment in the first year of life is essential to ensure early detection of specific developmental delays and impairments, and to ensure timely referral for early intervention. Early intervention is not only important in optimizing long-term outcomes for the child, but it also plays an important role in enhancing the parent-child relationship and parental well-being. In this review, we discuss the role of the developmental allied health team in the follow-up of high-risk infants, identify key assessment tools used in early neurodevelopmental surveillance, and provide recommendations regarding referral to intervention programs to optimize child and family outcomes. [Pediatr Ann. 2018;47(4):e165-e171.].

Preterm and term-equivalent age general movements and 1-year neurodevelopmental outcomes for infants born before 30 weeks' gestation

AIM

To examine the associations between Prechtl's General Movements Assessment (GMA), conducted from birth to term-equivalent age, and neurodevelopmental outcomes at 12 months corrected age, in infants born very preterm.

METHOD

One hundred and thirty-seven infants born before 30 weeks' gestation had serial GMA (categorized as 'normal' or 'abnormal') before term and at term-equivalent age. At 12 months corrected age, neurodevelopment was assessed using the Alberta Infant Motor Scale (AIMS); Neurological, Sensory, Motor, Developmental Assessment (NSMDA); and Touwen Infant Neurological Examination (TINE). The relationships between GMA at four time points and 12-month neurodevelopmental assessments were examined using regression models.

RESULTS

Abnormal GMA at all time points were associated with worse continuous scores on the AIMS, NSMDA, and TINE (p<0.05). Abnormal GMA before term and at term-equivalent age were associated with increased odds of mild-severe dysfunction on the NSMDA (odds ratio [OR] 4.26, 95% confidence interval [CI] 1.55-11.71, p<0.01; and OR 4.16, 95% CI 1.55-11.17, p<0.01 respectively) and abnormal GMA before term with increased odds of suboptimal-abnormal motor function on the TINE (OR 2.75, 95% CI 1.10-6.85, p=0.03).

INTERPRETATION

Abnormal GMA before term and at term-equivalent age were associated with worse neurodevelopment at 12 months corrected age in children born very preterm.

WHAT THIS PAPER ADDS

Abnormal general movements before term predict developmental deficits at 1 year in infants born very preterm. General Movements Assessment before term identifies at-risk infants born very preterm.

Continuum of neurobehaviour and its associations with brain MRI in infants born preterm

BACKGROUND

Infants born very preterm (VPT) and moderate-to-late preterm (MLPT) are at increased risk of long-term neurodevelopmental deficits, but how these deficits relate to early neurobehaviour in MLPT children is unclear. The aims of this study were to compare the neurobehavioural performance of infants born across three different gestational age groups: preterm <30 weeks' gestational age (PT<30); MLPT (32-36 weeks' gestational age) and term age (≥37 weeks' gestational age), and explore the relationships between MRI brain abnormalities and neurobehaviour at term-equivalent age.

METHODS

Neurobehaviour was assessed at term-equivalent age in 149 PT<30, 200 MLPT and 200 term-born infants using the Neonatal Intensive Care UnitNetwork Neurobehavioral Scale (NNNS), the Hammersmith Neonatal Neurological Examination (HNNE) and Prechtl's Qualitative Assessment of General Movements (GMA). A subset of 110 PT<30 and 198 MLPT infants had concurrent brain MRI.

RESULTS

Proportions with abnormal neurobehaviour on the NNNS and the HNNE, and abnormal GMA all increased with decreasing gestational age. Higher brain MRI abnormality scores in some regions were associated with suboptimal neurobehaviour on the NNNS and HNNE. The relationships between brain MRI abnormality scores and suboptimal neurobehaviour were similar in both PT<30 and MLPT infants. The relationship between brain MRI abnormality scores and abnormal GMA was stronger in PT<30 infants.

CONCLUSIONS

There was a continuum of neurobehaviour across gestational ages. The relationships between brain abnormality scores and suboptimal neurobehaviour provide evidence that neurobehavioural assessments offer insight into the integrity of the developing brain, and may be useful in earlier identification of the highest-risk infants.

Neuropredictors of oromotor feeding impairment in 12month-old children

BACKGROUND

Feeding impairment is prevalent in children with neurodevelopmental issues. Neuroimaging and neurobehavioral outcomes at term are predictive of later neuromotor impairment, but it is unknown whether they predict feeding impairment.

AIMS

To determine whether neurobehavior and brain magnetic resonance imaging (MRI) at term predict oromotor feeding at 12 months in preterm and term-born children.

STUDY DESIGN

Prospective cohort study.

SUBJECTS

248 infants (97 born <30 weeks and 151 born at term) recruited at birth.

OUTCOME MEASURES

Neurobehavioral assessments (General Movements (GMA), Hammersmith Neonatal Neurological Examination (HNNE), Neonatal Intensive Care Unit Network Neurobehavioral Scale (NNNS)); and brain MRI were administered at term-equivalent age. Oromotor feeding was assessed at 12 months corrected age using the Schedule for Oral Motor Assessment.

RESULTS

49/227 children had oromotor feeding impairment. Neurobehavior associated with later feeding impairment was: suboptimal NNNS stress (odds ratio [OR] 2.68; 95% confidence interval [CI] 1.20–6.01), non-optimal reflexes (OR 3.33; 95% CI 1.37–8.11) and arousal scales (OR 2.54; 95% CI 1.03–6.27); suboptimal HNNE total (OR 4.69; 95% CI 2.20–10.00), reflexes (OR 2.62; 95% CI 1.06–6.49), and tone scores (OR 3.87; 95% CI 1.45–10.35); and abnormal GMA (OR 2.60; 95% CI 1.21–5.57). Smaller biparietal diameter also predicted feeding impairment (OR 0.88; 95% CI 0.79–0.97). There was little evidence that relationships differed between birth groups.

CONCLUSIONS

Neurobehavior and biparietal diameter at term are associated with oromotor feeding at 12 months. These results may identify children at greatest risk of oromotor feeding impairment.

Association Between Moderate and Late Preterm Birth and Neurodevelopment and Social-Emotional Development at Age 2 Years

IMPORTANCE

Moderate and late preterm (MLPT) births comprise most preterm infants. Therefore, long-term developmental concerns in this population potentially have a large public health influence. While there are increasing reports of developmental problems in MLPT children, detail is lacking on the precise domains that are affected.

OBJECTIVE

To compare neurodevelopment and social-emotional development between MLPT infants and term-born control infants at age 2 years.

DESIGN, SETTING, AND PARTICIPANTS

This investigation was a prospective longitudinal cohort study at a single tertiary hospital. Participants were MLPT infants (32-36 weeks' completed gestation) and healthy full-term controls (≥37 weeks' gestation) recruited at birth. During a 3-year period between December 7, 2009, and November 7, 2012, MLPT infants were recruited at birth from the neonatal unit and postnatal wards of the Royal Women's Hospital, Melbourne, Australia. The term control recruitment extended to March 26, 2014. The dates of the data developmental assessments were February 23, 2012, to April 8, 2016.

EXPOSURE

Moderate and late preterm birth.

MAIN OUTCOMES AND MEASURES

Cerebral palsy, blindness, and deafness assessed by a pediatrician; cognitive, language, and motor development assessed using the Bayley Scales of Infant Development-Third Edition (developmental delay was defined as less than -1 SD relative to the mean in controls in any domain of the scales); and social-emotional and behavioral problems assessed by a parent questionnaire (Infant Toddler Social Emotional Assessment). Outcomes were compared between birth groups using linear and logistic regression, adjusted for social risk.

RESULTS

In total, 198 MLPT infants (98.5% of 201 recruited) and 183 term-born controls (91.0% of 201 recruited) were assessed at 2 years' corrected age. Compared with controls, MLPT children had worse cognitive, language, and motor development at age 2 years, with adjusted composite score mean differences of -5.3 (95% CI, -8.2 to -2.4) for cognitive development, -11.4 (95% CI, -15.3 to -7.5) for language development, and -7.3 (95% CI, -10.6 to -3.9) for motor development. The odds of developmental delay were higher in the MLPT group compared with controls, with adjusted odds ratios of 1.8 (95% CI, 1.1-3.0) for cognitive delay, 3.1 (95% CI, 1.8-5.2) for language delay, and 2.4 (95% CI, 1.3-4.5) for motor delay. Overall social-emotional competence was worse in MLPT children compared with controls (t statistic mean difference, -3.6 (95% CI, -5.8 to -1.4), but other behavioral domains were similar. The odds of being at risk for social-emotional competence were 3.9 (95% CI, 1.4-10.9) for MLPT children compared with controls.

CONCLUSIONS AND RELEVANCE

Moderate and late preterm children exhibited developmental delay compared with their term-born peers, most marked in the language domain. This knowledge of developmental needs in MLPT infants will assist in targeting surveillance and intervention.

Neurobehaviour at term-equivalent age and neurodevelopmental outcomes at 2 years in infants born moderate-to-late preterm

AIM

To examine the association between newborn neurobehavioural assessments and neurodevelopmental outcomes at 2 years in infants born moderate-to-late preterm (MLPT).

METHOD

Two-hundred and one infants born MLPT (born 32-36⁺⁶ wks' gestation) were assessed with the Hammersmith Neonatal Neurological Examination (HNNE) and NICU Network Neurobehavioral Scale (NNNS), with suboptimal performance defined as scores lower than the 10th centile. Development was assessed at 2 years corrected age with the Bayley Scales of Infant and Toddler Development 3rd Edition, with delay defined as scores less than 1 standard deviation (SD) below the mean. The relationships between neurobehaviour at term and Bayley-III cognitive, language, and motor scales at 2 years were examined using linear regression.

RESULTS

Increased odds for cognitive delay were associated with suboptimal HNNE total scores (odds ratio [OR] 2.66; 95% confidence interval [CI] 1.14-6.23, p=0.020) and suboptimal NNNS excitability (OR 3.01; 95% CI 1.33-6.82, p=0.008) and lethargy (OR 4.05; 95% CI 1.75-9.31, p=0.001) scores. Suboptimal lethargy scores on the NNNS were associated with increased odds of language (OR 5.64; 95% CI 1.33-23.85, p=0.019) and motor delay (OR: 6.86; 95% CI 1.64-28.71, p=0.08).

INTERPRETATION

Suboptimal performance on specific aspects of newborn neurobehavioural assessments is associated with neurodevelopmental delay at 2 years in children born MLPT.

Reliability of Neurobehavioral Assessments from Birth to Term Equivalent Age in Preterm and Term Born Infants

Neurobehavioral assessments provide insight into the functional integrity of the developing brain and help guide early intervention for preterm (<37 weeks' gestation) infants. In the context of shorter hospital stays, clinicians often need to assess preterm infants prior to term equivalent age. Few neurobehavioral assessments used in the preterm period have established interrater reliability.

AIM

To evaluate the interrater reliability of the Hammersmith Neonatal Neurological Examination (HNNE) and the NICU Network Neurobehavioral Scale (NNNS), when used both preterm and at term (>36 weeks).

METHODS

Thirty-five preterm infants and 11 term controls were recruited. Five assessors double-scored the HNNE and NNNS administered either preterm or at term. A one-way random effects, absolute, single-measures interclass correlation coefficient (ICC) was calculated to determine interrater reliability.

RESULTS

Interrater reliability for the HNNE was excellent (ICC > 0.74) for optimality scores, and good (ICC 0.60-0.74) to excellent for subtotal scores, except for 'Tone Patterns' (ICC 0.54). On the NNNS, interrater reliability was predominantly excellent for all items. Interrater agreement was generally excellent at both time points.

CONCLUSIONS

Overall, the HNNE and NNNS neurobehavioral assessments demonstrated mostly excellent interrater reliability when used prior to term and at term.

Motor trajectories from birth to 5 years of children born at less than 30 weeks' gestation: early predictors and functional implications. Protocol for a prospective cohort study

INTRODUCTION

Motor impairments are one of the most frequently reported adverse neurodevelopmental consequences in children born < 30 weeks' gestation. Up to 15% of children born at < 30 weeks have cerebral palsy and an additional 50% have mild to severe motor impairment at school age. The first 5 years of life are critical for the development of fundamental motor skills. These skills form the basis for more complex skills that are required to competently and confidently participate in schooling, sporting and recreational activities. In children born at < 30 weeks' gestation, the trajectory of motor development from birth to 5 years is not fully understood. The neural alterations that underpin motor impairments in these children are also unclear. It is essential to determine if early clinical evaluations and neuroimaging biomarkers can predict later motor impairment and associated functional problems at 5 years of age. This will help to identify children who will benefit the most from early intervention and improve functional outcomes at school age.

RESEARCH AIMS

The primary aim of this study is to compare the prevalence of motor impairment from birth to 5 years of age between children born at < 30 weeks and term-born controls, and to determine whether persistent abnormal motor assessments in the newborn period in those born at < 30 weeks predict abnormal motor functioning at 5 years of age. Secondary aims for children born at < 30 weeks and term-born children are: 1) to determine whether novel early magnetic resonance imaging-based structural or functional biomarkers that can predict motor impairments at 5 years are detectable in the neonatal period; 2) to investigate the association between motor impairments and concurrent deficits in body structure and function at 5 years of age; and 3) to explore how motor impairments at 5 years (including abnormalities of gait, postural control and strength) are associated with concurrent functional outcomes, including physical activity, cognitive ability, learning ability, and behavioural and emotional problems.

DESIGN

Prospective longitudinal cohort study.

PARTICIPANTS AND SETTING

150 preterm children (born at < 30 weeks' gestation) and 151 term-born children (born at > 36 completed weeks' gestation and weighing > 2499g) admitted to the Royal Women's Hospital, Melbourne, were recruited at birth and will be invited to participate in a 5-year follow-up study.

PROCEDURE

This study will examine previously collected data (from birth to 2 years) that comprise detailed motor assessments, and structural and functional brain MRI images. At 5 years, preterm and term, children will be examined using comprehensive motor assessments, including: the Movement Assessment Battery for Children (2nd edition) and measures of gait function through spatiotemporal (assessed with the GAITRite® Walkway) and dynamic postural control (assessed with Microsoft Kinect) variables; and hand grip strength (assessed with a dynamometer); and measures of physical activity (assessed using accelerometry), cognitive development (assessed with Wechsler Preschool and Primary Scale of Intelligence), and emotional and behavioural status (assessed with the Strengths and Difficulties Questionnaire and the Developmental and Wellbeing Assessment). At the 5-year assessment, parents/caregivers will be asked to complete questionnaires on demographics, physical activity, activities of daily living, behaviour, additional therapy (eg, physiotherapy and occupational therapy), and motor function (assessed with Pediatric Evaluation of Disability Inventory, Pediatric Quality of Life Questionnaire, the Little Developmental Co-ordination Questionnaire and an activity diary).

ANALYSIS

For the primary aim, the prevalence of motor impairment from birth to 5 years will be compared between children born at < 30 weeks and at term, using the proportion of children classified as abnormal at each of the time points (term age, 1, 2 and 5 years). Persistent motor impairments during the neonatal period will be assessed as a predictor of severity of motor impairment at 5 years of age in children born < 30 weeks using linear regression. Models will be fitted using generalised estimating equations to allow for the clustering of multiple births. Analysis will be repeated with adjustment for predictors of motor outcome, including additional therapy, sex, brain injury and chronic lung disease.

DISCUSSION/SIGNIFICANCE

Understanding the developmental precursors of motor impairment in children born before 30 weeks is essential for limiting disruption to skill development, and potential secondary impacts on physical activity, participation, academic achievement, self-esteem and associated outcomes (such as obesity, poor physical fitness and social isolation). An improved understanding of motor skill development will enable targeting of interventions and streamlining of services to children at highest risk of motor impairments.

Early general movements and brain magnetic resonance imaging at term-equivalent age in infants born <30weeks' gestation

BACKGROUND

Neurodevelopmental assessments and brain magnetic resonance imaging (MRI) at term-equivalent age (TEA) predict developmental outcomes in preterm infants. However, the relationship between neurodevelopment prior to term and cerebral structure is currently unknown.

AIMS

To examine the relationships between General Movements (GMs) assessed from birth to TEA and brain MRI at TEA in infants born <30weeks' gestation.

STUDY DESIGN

Prospective cohort study. GMs (categorised as 'normal' or 'abnormal') were recorded weekly from birth to 32weeks, and at 34 and 36weeks' postmenstrual age. At TEA, GMs were assessed concurrently with brain MRI (using a validated scoring system).

SUBJECTS

149 infants born <30weeks' gestation were recruited from a tertiary hospital.

RESULTS

103 infants had MRI at TEA and GMs recorded. Abnormal GMs prior to term were associated with cortical grey matter abnormality (p<0.03), deep grey matter abnormality (p=0.02) and increased interhemispheric distance (p<0.02). Abnormal GMs at TEA (n=55/90) were associated with more global brain abnormality (p<0.01) and cortical grey matter abnormality (p=0.01), and decreased transcerebellar diameter (p=0.04) on concurrent brain MRI.

CONCLUSIONS

Abnormal GMs both prior to term and at TEA were associated with more marked brain abnormality, and smaller brains at TEA. Abnormal GMs are an early marker of brain abnormalities in very preterm infants.

Neurobehaviour and neurological development in the first month after birth for infants born between 32-42 weeks' gestation

AIMS

The objective of this study was to generate reference values for infants born moderate preterm (MPT), late preterm (LPT) and full term (FT) for three newborn neurobehavioural/neurological examinations in the first weeks after birth.

STUDY DESIGN

Prospective cohort study to examine the expected range of values for MPT (born 32(+0) to 33(+6)), LPT (34(+0) to 36(+6)) and FT (born 37 to 42weeks' gestation) infants' performance on the Hammersmith Neonatal Neurological Examination (HNNE), the Neonatal Intensive Care Unit Network Neurobehavioural Scale (NNNS) and Prechtl's General Movements Assessment (GMA) in the first weeks after birth. Further, to determine the effects of sex, gestational age at birth, and postmenstrual age at assessment on the 3 different assessments within the gestational age groups.

SUBJECTS

80 MPT, 129 LPT and 201 FT infants were recruited shortly after birth from a tertiary hospital.

RESULTS

The means, standard deviations and 5th, 10th, 25th, 50th, 75th, 90th and 95th centiles are presented for the HNNE and NNNS for each of the three gestational age groups. Overall, FT infants performed better than MPT and LPT infants. The rate of normal GMA within the first few weeks after birth was 25% for MPT, 32% for LPT, and 90% for FT infants. The effects of sex, gestational age at birth, and postmenstrual age at assessment varied between test and gestational age groups.

CONCLUSIONS

This study provides normative data for the HNNE, NNNS, and GMA administered within the first weeks after birth in a sample of MPT, LPT and healthy FT infants.

Trajectories of general movements from birth to term-equivalent age in infants born <30 weeks' gestation

BACKGROUND

General movements (GMs) is an assessment with good predictive validity for neurodevelopmental outcomes in preterm infants. However, there is limited information describing the early GMs of very preterm infants, particularly prior to term.

AIMS

To describe the early GMs trajectory of very preterm infants (born <30weeks' gestation) from birth to term-equivalent age, and to assess the influence of known perinatal risk factors on GMs.

STUDY DESIGN

Prospective cohort study.

SUBJECTS

149 very preterm infants born <30weeks' gestation.

OUTCOME MEASURES

GMs were recorded weekly from birth until 32weeks' postmenstrual age, and then fortnightly until 38weeks' postmenstrual age. GMs were also assessed at term-equivalent age. Detailed perinatal data were collected.

RESULTS

Of 669 GMs assessed, 551 were preterm and 118 were at term-equivalent age. Prior to term, 15% (n=82) of GMs were normal and 85% (n=469) were abnormal, with the proportion of abnormal GMs decreasing with increasing postmenstrual age (p for trend <0.001). By term-equivalent 30% (n=35) of GMs were normal. On univariable analysis, lower gestational age (p<0.001), postnatal infection (p<0.001) and bronchopulmonary dysplasia (p=0.001) were associated with abnormal GMs. Postnatal infection was the only independent perinatal association with abnormal GMs on multivariable analysis. All four infants with grade III/IV intraventricular haemorrhage (IVH) had persistently abnormal GMs.

CONCLUSIONS

GMs were predominantly abnormal in very preterm infants, with a higher proportion of normal GMs at term-equivalent age than prior to term. Abnormal GMs were associated with postnatal infection and IVH.

Genetic relatedness of commensal Escherichia coli from nursery pigs in intensive pig production in Denmark and molecular characterization of genetically different strains

AIMS

To determine the genetic relatedness and the presence of virulence and antibiotic resistance genes in commensal Escherichia coli from nursery pigs in Danish intensive production.

METHODS AND RESULTS

The genetic diversity of 1000 E. coli strains randomly picked (N = 50 isolates) from cultured faecal samples (N = 4 pigs) from five intensive Danish pigs farms was analysed by repetitive extragenic palindromic-PCR (REP-PCR) and 42 unique REP-profiles were detected (similarity <92%). One profile was dominant (67.2% of strains) but farms differed significantly in the diversity of commensal E. coli: between eight and 21 different profiles per farm were detected. One to three strains representing each REP-profile were characterized by multilocus typing scheme-typing, as well as for presence of antimicrobial and virulence genes and serogrouping through microarray analysis. The 42 REP-profiles were classified into 22 different sequence types (ST) with ST10 being the most common, encompassing 10 REP-profiles. Resistance and virulence genes were detected in most of the isolates. Genes encoding AmpC-β-lactamases and quinolone resistance were found in one and three isolates, respectively. Toxin-producing genes were observed in 20 isolates.

CONCLUSIONS

A low genetic diversity was found in commensal gut E. coli from nursery pigs in Denmark. No correlation was observed between REP-profiles, ST-types and resistance/virulence patterns.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is the first study analysing in depth the genetic variability of commensal E. coli from pigs in Danish intensive pig production. A tendency for higher diversity was observed with in nursery pigs that were treated with zinc oxide only, in absence of other antimicrobials. Strains with potential to disseminate virulence and antibiotic resistance genes to pathogenic subgroups of E. coli were found to be wide-spread.

UV-B and temperature enhancement affect spring and autumn phenology in Populus tremula

Perennial plants growing at high latitudes synchronize growth and dormancy to appropriate seasons by sensing environmental cues. Autumnal growth cessation, bud set and dormancy induction are commonly driven by the length of photoperiod and light quality, and the responses are modified by temperature. However, although ultraviolet (UV)-B radiation is well known to affect plant growth and development, information on the effects on bud phenology is scarce. We examined the separate and combined effects of enhanced temperature and UV-B on autumnal bud set and spring bud break in female and male clones of Populus tremula in an outdoor experiment in Joensuu, Eastern Finland. Enhancements of UV-B and temperature were modulated to +30% and +2 °C, respectively, from June to October 2012. Enhanced UV-B accelerated bud set, while increased temperature delayed it. For both UV-B and temperature, we found sex-related differences in responsiveness. Temperature increase had a stronger delaying effect on bud maturation in male compared with female clones. Also, male clones were more responsive to UV-B increase than female clones. Increasing autumnal temperature enhanced bud break in spring for both sexes, while UV-B enhanced bud break in male clones. In conclusion, we found that UV-B affected phenological shifts in P. tremula, and that temperature and UV-B affected genders differently.

Antimicrobial resistance in faecal samples from buffalo, wildebeest and zebra grazing together with and without cattle in Tanzania

AIM

The aim of this study was to determine whether the practice of co-grazing with cattle and wild life constitutes a risk of transmission of antibiotic resistant bacteria to wild ungulates.

METHODS AND RESULTS

Faecal samples were collected from buffalo (n = 35), wildebeest (n = 40), zebra (n = 40) and cattle (N = 20) from Mikumi National Park, Tanzania (MNP), where cattle is prohibited and from Ngorongoro Conservation Area (NCA) where co-grazing is practiced. The number of coliforms and enterococci resistant to selected antibiotics was determined. Wild life generally harboured higher number of resistant Escherichia coli and Enterococci than cattle, but with no general influence in wild life of co-grazing with cattle. Vancomycin-resistant Enterococci were detected in wild life samples, and E. coli resistant to cefotaxime and enrofloxacin were observed among isolates from all wild life, but not from cattle. Culture independent estimates of the number of sulII gene copies obtained by qPCR did not differ between wild life from the two sample sites, while tetW was significantly higher in samples from MPN than from NCA.

CONCLUSIONS

Antibiotic resistant bacteria were not more frequently found in ungulates grazing together with cattle than ungulates without this interaction.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study did not indicate that transmission of antibiotic resistant bacteria is a frequent event following co-grazing of wild life and cattle.

Demonstration of persistent contamination of a cooked egg product production facility with Salmonella enterica serovar Tennessee and characterization of the persistent strain

AIMS

The aim of this study was to investigate whether continuous contamination of light pasteurized egg products with Salmonella enterica serovar Tennessee (S. Tennessee) at a large European producer of industrial egg products was caused by persistent contamination of the production facility and to characterize the persistent strains.

METHODS AND RESULTS

Seventy-three S. Tennessee isolates collected from products over a 3-year period with intermittent contamination, and 15 control strains were compared by pulsed field gel electrophoresis (PFGE) using two enzymes. Forty-five case isolates distributed throughout the full period were shown to belong to one profile type. Isolates representing different PFGE profiles were all assigned to ST 319 by multilocus sequence typing (MLST). The case isolates did not show a higher ability to form biofilm on a plastic surface than noncase isolates. Characteristically, members of the persistent clone were weak producers of H2 S in laboratory medium. S. Tennessee isolated from the case was able to grow better in pasteurized egg product compared with other serovars investigated.

CONCLUSIONS

It was concluded that the contamination was caused by a persistent strain in the production facility and that this strain apparently had adapted to grow in the relevant egg product.

SIGNIFICANCE AND IMPACT OF THE STUDY

S. Tennessee has previously been associated with persistence in hatching facilities. This is the first report of persistent contamination of an egg production facility with this serovar.

Molecular epidemiology of Salmonella gallinarum in chickens in Tanzania

A molecular epidemiological investigation of Salmonella gallinarum infection in scavenging local chickens and commercial layers in Tanzania was conducted between August 1997 and April 1998. A total of 1152 chickens were randomly selected from 10 villages and seven commercial farms. For serological and cultural prevalence studies, 1152 blood samples and 912 cloacal swabs were collected. In scavenging local chickens, the individual serological and cultural prevalences were 6.3 and 0%, while the prevalences were significantly higher in commercial layers at 18.4 and 2.6% (P < 0.001), respectively. The risk of infection in flocks of scavenging local chickens that had contact with commercial chickens was six times greater than the risk of infection in flocks of scavenging local chickens that had no contact with commercial chickens. Thirty-four S. gallinarum isolated from commercial chickens in this study, together with 29 Tanzanian historical isolates, were characterized using plasmid profiling and ribotyping. Fifty-one isolates contained both 85 and 2.5kb plasmids, five isolates contained only one plasmid of 85kb, and seven isolates had no plasmids. Ribotyping using HindIII restriction endonuclease demonstrated seven different ribotypes. Forty-seven isolates had similar results in both typing systems, suggesting they belonged to one clone. It is concluded that S. gallinarum infection in chickens in Tanzania is more prevalent in commercial layers than in scavenging local chickens. One strain of S. gallinarum from chickens first isolated in a Dar es Salaam hatchery was found to be common throughout the country.

A new real-time PCR method for the identification of Salmonella Dublin

AIMS

Development of a real-time PCR method for the specific detection of Salmonella Dublin.

METHODS AND RESULTS

The method was directed towards a Salm. Dublin-specific sequence of the vagC gene on the Salmonella virulence plasmid (pSDV) and towards Salmonella genus-specific sequence of the invA gene, serving as an internal amplification control. The method showed 100% inclusivity and exclusivity when tested on a strain collection containing 50 serotyped S . Dublin strains, 20 strains of other Salmonella serotypes and 10 non- Salmonella strains. The method also showed 100% inclusivity and 99% exclusivity in a collaborative study comprising eight laboratories, where each laboratory received ten different S . Dublin strains and 10 other Salmonella serotypes.

CONCLUSIONS

The method showed excellent performance both when validated in the laboratory and in the collaborative study.

SIGNIFICANCE AND IMPACT OF THE STUDY

Application of the present method in food control, for example at slaughterhouses, can improve the contamination control of this veterinary and clinically important Salmonella serotype.

The importance of motility and chemotaxis for extra-animal survival of Salmonella enterica serovar Typhimurium and Dublin

AIMS

This study investigated the importance of flagella and motility of Salmonella enterica serovar Typhimurium and Dublin in models of extra-animal survival.

METHODS AND RESULTS

The study was performed using transposon mutants in flagella genes fliC and fljB and in chemotaxis genes cheA, cheB and cheR. Flagella and chemotaxis were found to be of minor importance for attachment to plant leaves, survival in liquid manure and interaction with the nematode C. elegans, while differences were observed between the fliC mutant and the wild-type strain of S. Dublin in interactions with amoebae.

CONCLUSIONS

The study shows that flagella and chemotaxis play a minor role in extra-animal survival of these two serovars of Salmonella under the conditions tested.

SIGNIFICANCE AND IMPACT OF THE STUDY

Extra-animal survival is important in the full infection cycle for zoonotic salmonellae. Such serovars are motile. Even though the current study was only based on the characterization of two serovars, it strongly suggests that motility and chemotaxis are of minor importance during the spread of Salmonella from one animal to the next through the external environment.

Time-course investigation of infection with a low virulent Pasteurella multocida strain in normal and immune-suppressed 12-week-old free-range chickens

Twelve-week-old indigenous chickens, either immune-suppressed using dexamethasone (IS) or non-immune-suppressed (NIS), were challenged with a low virulent strain, Pasteurella multocida strain NCTC 10322(T), and developed clinical signs and pathological lesions typical of chronic fowl cholera. NIS birds demonstrated much more severe signs of fowl cholera than IS birds. With few exceptions, signs recorded in IS and NIS birds were of the same types, but significantly milder in the IS birds, indicating that immune suppression does not change the course of infection but rather the severity of signs in fowl cholera. P. multocida signals by fluorescent in situ hybridization (FISH) were observed between 1 h and 14 days in the lungs, trachea, air sacs, liver, spleen, bursa of Fabricius and caecal tonsils, while signals from other organs mostly were observed after 24 h. More organs had FISH signals in NIS birds than in IS birds and at higher frequency per organ. Many organs were positive by FISH even 14 days post infection, and it is suggested that these organs may be likely places for long-term carriage of P. multocida following infection. The present study has demonstrated the spread of P. multocida in different tissues in chickens and distribution of lesions associated with chronic fowl cholera, and pointed to a decrease of pathology in IS birds. Since dexamethasone mostly affects heterophils, the study suggests that these cells play a role in the development of lesions associated with chronic fowl cholera in chickens.

Survival of Salmonella on cuts of beef carcasses subjected to dry aging

AIMS

The aim of this study was to determine the survival of 15 different strains of Salmonella of selected serotypes during prolonged cold storage of beef.

METHODS AND RESULTS

Fifteen strains of eight different serotypes of Salmonella were spiked onto fresh cuts beef portions, and the survival was followed during storage in a laboratory cooling system. Over a 14-day period, all strains were reduced significantly in numbers; however, strains of Salmonella Typhimurium DT104 and Salmonella Enteritidis PT4 and PT8 survived significantly longer than strains of the serovars Dublin, Derby, Infantis and Newport. For five selected strains, the observations were verified in a pilot plant cooling facility mimicking industrial cooling. No significant differences in reduction were found between the two cooling methods.

CONCLUSIONS

A significant reduction in Salmonella can be obtained by dry aging of beef during cold storage but the survival is strain dependent.

SIGNIFICANCE AND IMPACT OF THE STUDY

From a hygienic point of view, cold storage of unpacked beef, which is still performed in small slaughterhouses, is a good alternative to vacuum packaging.

Ribotypes of Salmonella enterica serovar Gallinarum biovars gallinarum and pullorum

Ninety-four isolates of Salmonella enterica serovar Gallinarum biovar pullorum and forty-one isolates of biovar gallinarum were ribotyped using the enzymes, HindIII, EcoRI and SmaI, and a digoxigenin-labelled E. coli-derived rRNA probe. Using HindIII, 13 profile types were observed within biovar gallinarum and 12 within biovar pullorum. The most common types accounted for 39% of biovar pullorum isolates and 47% for biovar gallinarum. EcoRI digests revealed two profile types within biovar pullorum, one accounting for 96% of the isolates, and three EcoRI profiles within biovar gallinarum, with 81% of the isolates belonging to the dominant type. Using SmaI, biovar pullorum showed two profile types with 94% of the isolates belonging to the dominant one, while SmaI digestion revealed only one ribotype within biovar gallinarum. The SmaI ribotype of biovar gallinarum was identical to the less common of the two SmaI types in biovar pullorum. Two of the HindIII profile types were seen in both biovars. The two biovars did not share any of the EcoRI profiles. Numerical analysis based on the ribotypes revealed a 94% similarity between the two biovars, but they clustered separately in a similarity dendrogram, underlining the existence of two different biovars. The results indicate that ribotyping, especially using EcoRI, may be useful in separating biovars gallinarum and pullorum. The ribotypes obtained with isolates from different countries indicated that different clones of biovar gallinarum might exist in different regions.