Asthma-community acquired pneumonia co-diagnosis in children: a scoping review

OBJECTIVE

This scoping review investigated the existing literature and identified the evidence gaps related to diagnosis and management in children aged 2-18 years presenting to hospitals with a co-diagnosis of asthma and community-acquired pneumonia.

DATA SOURCES

We designed a scoping review following Arksey and O'Malley's scoping review framework and PRISMA extension for a scoping review. We searched literature using five electronic databases: PubMed, CINAHL, Scopus, Web of Science, and Embase from 2003 to June 2023.

RESULTS

A total of 1599 abstracts with titles were screened and 12 abstracts were selected for full review. Separate guidelines including Modified Global Initiative for Asthma (GINA) guidelines; modified Integrated Management of Childhood Illness (IMCI) guidelines; and a consensus guideline developed by the Pediatric Infectious Diseases Society (PIDS) and Infectious Diseases Society of America (IDSA) were used for diagnosing asthma and CAP individually. Chest X-rays were used in 83.3% (10/12) of studies to establish the co-diagnosis of asthma-CAP in children. Variations were observed in using different laboratory investigations across the studies. Infectious etiologies were detected in five (41.7%) studies. In 75% (9/12) of studies, children with asthma-CAP co-diagnosis were treated with antimicrobials, however, bacterial etiology was not reported in 44.4% (4/9) of the studies.

CONCLUSIONS

Our scoping review suggests that chest X-rays are commonly used to establish the co-diagnosis of asthma-CAP and antibiotics are often used without laboratory confirmation of a bacterial etiology. Clinical practice guidelines for the management of asthma and pneumonia in children who present with co-diagnosis may standardize clinical care and reduce variation.

Risk Factors and Clinical Prognosis Associated With RSV-ALRI Intensive Care Unit Admission in Children <2 Years of Age: A Multicenter Study

BACKGROUND

Respiratory syncytial virus (RSV) is the leading cause of acute lower respiratory infections (ALRIs) in children aged <2 years. Currently, there are limited data on risk factors for very severe RSV-ALRI requiring intensive care unit (ICU) admission.

METHODS

We conducted a case-control study of children aged <2 years admitted with RSV-ALRI to the Sydney Children's Hospital Network, comprising 2 large tertiary pediatric hospitals. Cases were children with laboratory-confirmed RSV-ALRI admitted to ICU, and controls were (1:2, matched on date of admission) children hospitalized with RSV-ALRI but not requiring ICU transfer. Data on risk factors were retrieved from the electronic medical record system. Adjusted odds ratios (aORs) with 95% confidence intervals (95% CI) associated with risk factors for ICU admission and the association with clinical and treatment factors were determined from logistic regression models.

RESULTS

A total of 44 (44%) of 100 cases and 90 (48.1%) of 187 controls were male. Age <6 months and preterm births were associated with a 2.10-fold (95% CI: 1.14-3.79) and 2.35-fold (95% CI: 1.26-4.41) increased risk in ICU admissions, respectively. The presence of any chronic health condition was a significant risk factor for ICU admission. The clinical presentations on admission more commonly seen in cases were apnea (aOR: 5.01, 95% CI: 1.50-17.13) and respiratory distress (aOR: 15.91, 95% CI: 4.52-55.97). Cases were more likely to be hospitalized for longer duration and require respiratory support.

CONCLUSIONS

Our results can be translated into a clinical risk algorithm to identify children at risk of very severe RSV disease.

Erratum: Asthma and Susceptibility to COVID-19 in Australian Children During Alpha, Delta and Omicron Waves of the COVID-19 Pandemic [Corrigendum]

[This corrects the article DOI: 10.2147/JAA.S421158.].

Asthma and Susceptibility to COVID-19 in Australian Children During Alpha, Delta and Omicron Waves of the COVID-19 Pandemic

Purpose

Earlier coronavirus-19 (COVID-19) pandemic reports did not implicate increased disease burden in asthmatics while subsequent findings have been inconsistent. To date, the impact of COVID-19 on childhood asthma remains undetermined and is further complicated with ongoing emergence of new variants. This study aimed to investigate association between asthma and COVID-19 for children in New South Wales (NSW), Australia and compare its differences across four major outbreaks from alpha, delta and omicron variants/subvariants.

Methods

This is a retrospective cross-sectional study of all children aged ≤17 years old who sought care for COVID-19 at Sydney Children's Hospitals Network (SCHN) between 1 January 2020 and 31 May 2022.

Results

Of the 18,932 children with polymerase chain reaction (PCR) confirmed COVID-19 who attended SCHN, 60% received their care during delta wave, and 5.41% (n = 913) had prior diagnosis of asthma. Among children with COVID-19, the odds of having asthma were lower during alpha (aOR = 0.43; 95% CI, 0.19-0.83) and delta wave (aOR = 0.84; 95% CI, 0.73-0.96), but were higher during omicron wave (aOR = 1.56; 95% CI, 1.23-1.95). Length of hospital stay (LOS) for asthmatic children were increased by 0.55 days and 1.17 days during delta and the second omicron wave, respectively. Intensive care and mechanical ventilation requirements were not significantly different between asthmatic and non-asthmatic children. Eleven deaths were reported but none had asthma.

Conclusion

Although children with asthma were more susceptible to COVID-19 infections during omicron waves compared to that of alpha or delta waves, they were not at greater risk of COVID-19 severity at any stage of the outbreak regardless of the predominant SARS-CoV-2 variants/subvariants.

Diet and the gut-lung axis in cystic fibrosis - direct & indirect links

Cystic fibrosis (CF) is a multisystem, autosomal, recessive disease primarily affecting the lungs, pancreas, gastrointestinal tract, and liver. Whilst there is increasing evidence of a microbial 'gut-lung axis' in chronic respiratory conditions, there has been limited analysis of such a concept in CF. We performed a comprehensive dietary and microbiota analysis to explore the interactions between diet, gastrointestinal microbiota, respiratory microbiota, and clinical outcomes in children with CF. Our results demonstrate significant alterations in intestinal inflammation and respiratory and gastrointestinal microbiota when compared to age and gender matched children without CF. We identified correlations between the gastrointestinal and respiratory microbiota, lung function, CF pulmonary exacerbations and anthropometrics, supporting the concept of an altered gut-lung axis in children with CF. We also identified significant differences in dietary quality with CF children consuming greater relative proportions of total, saturated and trans fats, and less relative proportions of carbohydrates, wholegrains, fiber, insoluble fiber, starch, and resistant starch. Our findings position the CF diet as a potential modulator in gastrointestinal inflammation and the proposed gut-lung axial relationship in CF. The dietary intake of wholegrains, fiber and resistant starch may be protective against intestinal inflammation and should be explored as potential therapeutic adjuvants for children with CF.

Monoclonal antibody treatments for paediatric severe asthma-outcomes, attitudes and adherence

Asthma prevalence in Australian children is amongst the highest in the world. Monoclonal antibody treatments (biologics) are the fifth step in the Global Initiative for Asthma guidelines to treat severe asthma. Our retrospective cohort study aimed to evaluate the effect of biologics for children with severe asthma, assess adherence and explore attitudes toward home administration using prefilled injection devices. We collected data for paediatric patients receiving biologics to compare asthma-related outcomes six-months pre and post initiation of therapy. Participant and parent surveys assessed perceived change in asthma control and attitudes to home injections. Eleven patients were recruited. Six-months post biologic treatment there were significant reductions in mean exhaled nitric oxide (-40ppb, p<0.05) and asthma control questionnaire 5 (ACQ-5) (-1.7, p<0.05). The mean number of hospitalisations and OCS courses were also less, although not statistically significant (p=0.53 and 0.17 respectively). There were no notable changes in mean percent-predicted FEV1, FVC or FEV1/FVC. 80% of patients and carers perceived slightly or much better asthma control on biologics and 80% of carers indicated they would be slightly or much happier with home-based injections. We conclude that biologics can improve asthma control. Whilst health-centre injections adherence is high, carers are interested in home injections.

Impact of integrated care coordination on pediatric asthma hospital presentations

INTRODUCTION

Frequent asthma attacks in children result in unscheduled hospital presentations. Patient centered care coordination can reduce asthma hospital presentations. In 2016, The Sydney Children's Hospitals Network launched the Asthma Follow up Integrated Care Initiative with the aim to reduce pediatric asthma emergency department (ED) presentations by 50% through developing and testing an integrated model of care led by care coordinators (CCs).

METHODS

The integrated model of care was developed by a multidisciplinary team at Sydney Children's Hospital Randwick (SCH,R) and implemented in two phases: Phase I and Phase II. Children aged 2-16 years who presented ≥4 times to the ED of the SCH,R in the preceding 12 months were enrolled in Phase I and those who had ≥4 ED presentations and ≥1 hospital admissions with asthma attack were enrolled in Phase II. Phase I included a suite of interventions delivered by CCs including encouraging parents/carers to schedule follow-up visits with GP post-discharge, ensuring parents/carers are provided with standard asthma resource pack, offering referrals to asthma education sessions, sending a letter to the child's GP advising of the child's recent hospital presentation and coordinating asthma education webinar for GPs. In addition, in Phase II CCs sent text messages to parents/carers reminding them to follow-up with the child's GP. We compared the change in ED visits and hospital admissions at baseline (6 months pre-enrolment) and at 6-and 12-months post-enrolment in the program.

RESULTS

During December 2016-January 2021, 160 children (99 in Phase I and 61 in Phase II) were enrolled. Compared to baseline at 6- and 12-months post-enrolment, the proportion of children requiring ≥1 asthma ED presentations reduced by 43 and 61% in Phase I and 41 and 66% in Phase II. Similarly, the proportion of children requiring ≥1 asthma hospital admissions at 6- and 12-months post-enrolment reduced by 40 and 47% in Phase I and 62 and 69% in Phase II.

CONCLUSION

Our results support that care coordinator led integrated model of asthma care which enables integration of acute and primary care services and provides families with asthma resources and education can reduce asthma hospital presentations in children.

Factors associated with "Frequent Exacerbator" phenotype in children with bronchiectasis: The first report on children from the Australian Bronchiectasis Registry

INTRODUCTION

In adults with bronchiectasis, multicentre data advanced the field including disease characterisation and derivation of phenotypes such as 'frequent exacerbator (FE)' (≥3 exacerbations/year). However, paediatric cohorts are largely limited to single centres and no scientifically derived phenotypes of paediatric bronchiectasis yet exists. Using paediatric data from the Australian Bronchiectasis Registry (ABR), we aimed to: (a) describe the clinical characteristics and compare Indigenous with non-Indigenous children, and (b) determine if a FE phenotype can be identified and if so, its associated factors.

METHODS

We retrieved data of children (aged <18-years) with radiologically confirmed bronchiectasis, enrolled between March 2016-March 2020.

RESULTS

Across five sites, 540 children [288 Indigenous; median age = 8-years (IQR 6-11)] were included. Baseline characteristics revealed past infection/idiopathic was the commonest (70%) underlying aetiology, most had cylindrical bronchiectasis and normal spirometry. Indigenous children (vs. non-Indigenous) had significantly more environmental tobacco smoke exposure (84% vs 32%, p < 0.0001) and lower birth weight (2797 g vs 3260 g, p < 0.0001). FE phenotype present in 162 (30%) children, was associated with being younger (OR_adjusted = 0.85, 95%CI 0.81-0.90), more recent diagnosis of bronchiectasis (OR_adjusted = 0.67; 95%CI 0.60-0.75), recent hospitalization (OR_adj = 4.51; 95%CI 2.45-8.54) and Pseudomonas aeruginosa (PsA) infection (OR_adjusted = 2.43; 95%CI 1.01-5.78). The FE phenotype were less likely to be Indigenous (OR_adjusted = 0.14; 95%CI 0.03-0.65).

CONCLUSION

Even within a single country, the characteristics of children with bronchiectasis differ among cohorts. A paediatric FE phenotype exists and is characterised by being younger with a more recent diagnosis, PsA infection and previous hospitalization. Prospective data to consolidate our findings characterising childhood bronchiectasis phenotypes are required.

Assessment of Variation in Care Following Hospital Discharge for Children with Acute Asthma

Purpose

To evaluate potential variation in care management pathways following hospital discharge for children with asthma in New South Wales, Australia.

Methods

A cross-sectional web-based survey was conducted in emergency departments (EDs) and paediatric units of public hospitals with more than five paediatric beds within New South Wales, Australia, between July 2018 and March 2019. Nursing and medical staff in EDs and paediatric units who had cared for children aged under 18 years with asthma in the preceding 12 months were invited to participate in this study. Outcome measures included use of clinical practice guidelines and asthma action plan (AAP); advice on post-hospitalization follow-up; provision of asthma education for parents/carers; availability of community-based asthma services; communication with schools/childcare services.

Results

A total of 502 participants (236 nursing and 266 medical staff, response rate=22%) from 37 hospitals were included. Overall, the use of AAP was not universal (median=90%; IQR=81–96%) with significant difference across local health districts (LHDs) (88.6%, 95% CI=85.4–91.3) and between EDs and paediatric wards (p=9.4×10⁻⁹); and a range of asthma clinical practice guidelines were used. Post-hospitalization follow-up within 2–3 days was recommended by 70% of the respondents, but only 8% reported that hospitals had a system in place to ensure follow-up compliance. Formal asthma education sessions (27% respondents) were seldom provided to parents/carers during hospital stays, especially in EDs (14% respondents). Less than 50% of the respondents were aware of any asthma community services for children and only 4% reported that schools/childcare services were notified about the child’s hospital admission for an asthma flare up.

Conclusion

There are marked variations in the post-hospitalization asthma care and community management for children in NSW. An integrated standardized model of care may improve health outcomes in children with asthma.

Rate of use and effectiveness of oseltamivir in the treatment of influenza illness in high-risk populations: A systematic review and meta-analysis

BACKGROUND

Oseltamivir is recommended in the treatment of influenza illness in high-risk populations, including those with chronic heart and lung diseases.

OBJECTIVES

We conducted a systematic review and meta-analysis to determine the rate of use and effectiveness of oseltamivir in these groups of patients.

METHODS

The protocol for the systematic review was registered on PROSPERO (CRD42019125998). Medline, EMBASE, Cochrane CENTRAL, and CINAHL were searched for observational studies and randomized controlled trials published up to 16 February 2020. Quality appraisal of final studies was conducted using GRADE guidelines. Data were extracted using a predeveloped template. Main outcomes measured included the rate of use of oseltamivir for influenza-like-illness and its effectiveness in reducing disease severity in patients with cardiopulmonary diseases. Outcomes measured for effectiveness were influenza-related complications (respiratory infections and asthma exacerbations), hospitalization rates, and time to freedom from illness. Risk of bias was assessed using Cochrane's Risk of Bias 2.0 tool for randomized trials and Cochrane's Risk of Bias in nonrandomized Studies of Interventions tool for nonrandomized trials. Where data were available, pooled analyses were conducted. Dichotomous variables were evaluated using the Mantel-Hansel method. A random effect model was applied. Summary measures were reported as risk ratios where relevant.

RESULTS

Our systematic review identified nine studies. Oseltamivir use ranged from 25% to 100%. When oseltamivir group was compared to placebo, rates of respiratory tract infections reduced by 28% (RR = 0.72, 95% CI = 0.59-0.90), hospitalization reduced by 52% (RR = 0.48, 95% CI = 0.28-0.80) and median time to illness alleviation decreased by 10.4 to 120 hours. There was no significant reduction in asthma exacerbation rates.

CONCLUSIONS

Our systematic review suggests that the use of oseltamivir is beneficial in reducing disease severity, however, its use in high-risk population remains suboptimal.

Community-based interventions for childhood asthma using comprehensive approaches: a systematic review and meta-analysis

Objective

We conducted a systematic review and meta-analysis to determine the effectiveness of comprehensive community-based interventions with ≥ 2 components in improving asthma outcomes in children.

Methods

A systematic search of Medline, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Excerpta Medica Database (EMBASE), Cochrane Library and hand search of reference collections were conducted to identify any research articles published in English between 2000 and 2019. All studies reporting community-based asthma interventions with ≥ 2 components (e.g., asthma self-management education, home environmental assessment or care coordination etc.) for children aged ≤ 18 years were included. Meta-analyses were performed using random-effects model to estimate pooled odds ratio (OR) with 95% confidence intervals (CIs).

Results

Of the 2352 studies identified, 21 studies were included in the final analysis: 19 pre-post interventions, one randomised controlled trial (RCT) and one retrospective study. Comprehensive asthma programs with multicomponent interventions were associated with significant reduction in asthma-related Emergency Department (ED) visits (OR = 0.26; 95% CI 0.20–0.35), hospitalizations (OR = 0.24; 95% CI 0.15–0.38), number of days (mean difference = − 2.58; 95% CI − 3.00 to − 2.17) and nights with asthma symptoms (mean difference = − 2.14; 95% CI − 2.94 to − 1.34), use of short-acting asthma medications/bronchodilators (BD) (OR = 0.28; 95% CI 0.16–0.51), and increase use of asthma action plan (AAP) (OR = 8.87; 95% CI 3.85–20.45).

Conclusion

Community-based asthma care using more comprehensive approaches may improve childhood asthma management and reduce asthma related health care utilization.

Development and validation of a risk score to identify children at risk of life-threatening asthma

OBJECTIVE

To develop and validate a prediction risk score for identification of children at risk of developing life-threatening asthma (LTA).

METHODS

Our study utilized existing medical records and retrospective analysis to develop and validate a risk score. The study population included children aged 2-17 years, admitted with a primary diagnosis of asthma, to Sydney Children's Hospital between 2011-2016. Children admitted in the intensive care unit with asthma at risk of LTA (cases) and those admitted into general ward (comparison group), were randomly divided into a derivation and a validation cohort. Candidate predictors from derivation cohort were selected through multivariable regression, which were used to estimate each child's risk of developing LTA in the validation cohort. Predictive performance of the risk score was evaluated by the area under the receiver operating characteristic curve (AUROC) and Hosmer-Lemeshow goodness-of-fit test.

RESULTS

The study population comprised of 1171 children; 586 in the derivation and 585 in the validation cohort. Four independent candidate variables from derivation cohort (age at admission, socioeconomic status, a family history of asthma/atopy and previous asthma hospitalizations) were retained in the predictive model (AUROC 0.759; 95% CI, 0.694-0.823), with a sensitivity of 78.5% and specificity of 46.6%.

CONCLUSIONS

Our risk algorithm based on routinely collected clinical data may be used to develop a user-friendly risk score for early identification and monitoring of children at risk of developing LTA.

Confirmation that candidatus Coxiella cheraxi from redclaw crayfish (Cherax quadricarinatus) is a close relative of Coxiella burnetii, the agent of Q-fever

A Coxiella sp. closely related to the agent of Q-fever, Coxiella burnetii, has been associated with mortalities in redclaw crayfish, (Cherax quadricarinatus), in farms and experimental facilities for three decades. Limited sequence data including 16S rRNA have placed the rickettsial species as a new species, candidatus C. cheraxi closely related to C. burnetii. MinION sequencing was conducted on the last remaining sample from an outbreak of disease, TO-98. The accuracy of base pair reads was mostly 99·9% (error rate 1 in 1000) or better. After filtering for reads of co-isolated Citrobacter freundii, 2629 sequences remained with the longest being 12 585 base pairs (bp). The longest 21 sequences are presented with their single best hit statistics when examined by NCBI blastn (nucleotides) and the nucleotides translated into proteins NCBI blastx. All sequences hit with either C. burnetii (29/42, 69%) or Coxiella (10/42, 24%) or rickettsia (3/42, 7%) with an error rate of less than 1 in 1 million for either bp or amino acids. Sequencing in this report confirms candidatus C. cheraxi is a new species very closely related to C. burnetii. SIGNIFICANCE AND IMPACT OF THE STUDY: This work reports on the use of newer technologies on archival samples and provides significantly more data on the currently limited genome data of candidatus Coxiella cheraxi, one of the few species isolated in the genus Coxiella. Candidatus Coxiella cheraxi causes death in redclaw crayfish and has been reported as being closely related to C. burnettii, the agent of Q-fever, based on 16S rRNA sequencing. This work provides confirmation for this claim.

Severe Asthma Toolkit: an online resource for multidisciplinary health professionals-needs assessment, development process and user analytics with survey feedback

OBJECTIVES

Severe asthma imposes a significant burden on individuals, families and the healthcare system. New treatment and management approaches are emerging as effective options for severe asthma. Translating new knowledge to multidisciplinary healthcare professionals is a priority. We developed 'The Severe Asthma Toolkit' (https://toolkit.severeasthma.org.au) to increase awareness of severe asthma, provide evidence-based resources and support decisionmaking by healthcare providers.

SETTING

Roundtable discussions and a survey of Australians clinicians were conducted to determine clinician preferences, format and content for a severe asthma resource.

PARTICIPANTS

A reference group from stakeholder and consumer bodies and severe asthma experts provided advice and feedback. A multidisciplinary team of international experts was engaged to develop content. Written content was based on up-to-date literature. Peer and editorial review were performed to finalise content and inform web design. Website design focused on user experience, navigation, engagement, interactivity and tailoring of content for a clinical audience.

RESULTS

A web-based resource was developed. Roundtable discussions and a needs assessment survey identified the need for dedicated severe asthma management resources to support skills training. The end-product, which launched 26 March 2018, includes an overview of severe asthma, diagnosis and assessment, management, medications, comorbidities, living with severe asthma, establishing a clinic, paediatrics/adolescents and clinical resources. Analytics indicate access by users worldwide (32 169 users from 169 countries). User survey results (n=394) confirm access by the target audience (72% health professionals), who agreed the toolkit increased their knowledge (73%) and confidence in managing severe asthma (66%), and 75% are likely to use the resource in clinic.

CONCLUSIONS

The Severe Asthma Toolkit is a unique, evidence-based internet resource to support healthcare professionals providing optimal care for people with severe asthma. It is a comprehensive, accessible and independent resource developed by leading severe asthma experts to improve clinician knowledge and skills in severe asthma management.

Glutathione S-Transferase Genotype Protects against In Utero Tobacco-linked Lung Function Deficits

Rationale: In utero tobacco exposure is associated with reduced lung function from infancy. Antioxidant enzymes from the glutathione S-transferase (GST) family may protect against these lung function deficits.Objectives: To assess the long-term effect of in utero smoke exposure on lung function into adulthood, and to assess whether GSTT1 and GSTM1 active genotypes have long-term protective effects on lung function.Methods: In this longitudinal study based on a general population (n = 253), lung function was measured during infancy and at 6, 11, 18, and 24 years. GSTM1 and GSTT1 genotype was analyzed in a subgroup (n = 179). Lung function was assessed longitudinally from 6 to 24 years (n = 199).Measurements and Main Results: Exposure to maternal in utero tobacco was associated with lower FEV₁ and FVC longitudinally from 6 to 24 years (mean difference, -3.87% predicted, P = 0.021; -3.35% predicted, P = 0.035, respectively). Among those homozygous for the GSTM1-null genotype, in utero tobacco exposure was associated with lower FEV₁ and FVC compared with those with no in utero tobacco exposure (mean difference, -6.2% predicted, P = 0.01; -4.7% predicted, P = 0.043, respectively). For those with GSTM1 active genotype, there was no difference in lung function whether exposed to maternal in utero tobacco or not. In utero tobacco exposure was associated with deficits in lung function among those with both GSTT1-null and GSTT1-active genotypes.Conclusions: Certain GST genotypes may have protective effects against the long-term deficits in lung function associated with in utero tobacco exposure. This offers potential preventative targets in antioxidant pathways for at-risk infants of smoking mothers.

Children with bronchiectasis have poorer lung function than those with cystic fibrosis and do not receive the same standard of care

BACKGROUND

Children with cystic fibrosis (CF) are routinely managed in a multidisciplinary clinic at tertiary pediatric centers. However, children with bronchiectasis may not be managed in the same way. We sought to compare the management model and clinical outcomes of children with bronchiectasis with children diagnosed with CF, in a single pediatric center.

METHODS

We identified patients with bronchiectasis from hospital medical records at an urban tertiary pediatric hospital and identified a sex- and age-matched CF patient at the same center to compare lung function, nutritional status, frequency of physiotherapy and respiratory physician visits, and number of microbiological samples taken for bacterial culture.

RESULTS

Twenty-two children with bronchiectasis were identified, mean (standard deviation [SD]) age was 11 (3) years. The most common known etiology for bronchiectasis was postinfective (6 of 22) but was unknown in 8 of 22. The cohort with bronchiectasis had poorer lung function (FEV1 mean [SD] percent predicted 78.6 [20.5] vs 94.5 [14.7], P = .005) and had less outpatient reviews by the respiratory physician (P < .001) and respiratory physiotherapist (P < .001) when compared to those with CF. Nutritional parameters did not differ between the groups. Many children (10 of 22, 45%) with bronchiectasis did not have any microbiological respiratory tract samples taken for evaluation.

CONCLUSION

Children with bronchiectasis at this institution have poorer lung function than children with CF, and are deserving of improved multidisciplinary care.

Prevalence of allergic sensitization, hay fever, eczema, and asthma in a longitudinal birth cohort

Purpose

The aim of this study was to longitudinally assess the prevalence of allergic sensitization, asthma, eczema and hay fever from infancy to adulthood in a single cohort.

Participants and methods

This prospective study is based on a longitudinal birth cohort of 253 participants, with respiratory and immunological assessments at 1, 6, 11, 18 and 24 years of age. Subjects were recruited from an urban maternity hospital. Retention rates varied from 45% to 72% at follow-up assessments. Asthma diagnosis was based on physician diagnosis of asthma and symptoms/medications in the previous 12 months. Allergic sensitization was defined by the positive skin prick test. Hay fever and eczema were based on a questionnaire.

Results

The prevalence of allergic sensitization rose from 19% (n=33) at 1 year of age to 71% (n=77) at 24 years of age. The rate of asthma halved from 25% at 6 years of age to 12%–15% between 11 and 24 years of age, but the prevalence of allergic sensitization among those with asthma doubled from 50% at 6 years of age to 100% at 24 years of age. Hay fever rates rose throughout childhood from 7% at 6 years of age to 44% at 24 years of age, while the prevalence of eczema reduced from 25% at 6 years of age to 16% at 24 years of age. Parental atopy doubled the odds of asthma in their offspring by 24 years of age (odds ratio [OR]= 2.63, 95% CI 1.1–6.2, p=0.029). In all, 74% of those with asthma at 24 years of age also reported hay fever. The relationship between eczema and asthma was only significant up to 11 years of age, and the relationship between hay fever and asthma was stronger in adolescence and early adulthood than in early childhood.

Conclusion

Patterns of atopic disorders vary throughout childhood. Although the prevalence of allergic sensitization and hay fever rose throughout childhood and the prevalence of asthma reduced, the strength of their relationship with asthma increased with age.

Airway function in infancy is linked to airflow measurements and respiratory symptoms from childhood into adulthood

INTRODUCTION

Increasing evidence suggests that poor lung function in adulthood is determined very early in life. Our study aims were: (1) identify factors associated with early infant lung function; (2) quantify the link between early infant lung function and early adult lung function; and (3) identify environmental and inherited factors which predict lung function throughout the post-natal growth period.

METHODS

In this longitudinal study, 253 individuals were recruited antenatally. Lung function and allergy testing occurred at 1, 6, 12 months, 6, 11, 18, and 24 years of age. The relationship between lung function at 1 month (V'maxFRC) and spirometry variables at each follow-up was evaluated. Early life predictors of spirometry were assessed longitudinally using linear mixed models.

RESULTS

V'maxFRC correlated positively with FEF25-75% at every assessment from 6 to 24 years and FEV₁ /FVC at 11 and 24 years and inversely with airway responsiveness at 6 and 18 years. Maternal asthma and smoking in pregnancy were associated with lower FEV₁ from 6 to 24 years (-99 mL, P = 0.03; -77 mL, P = 0.045 respectively). Lower V'maxFRC at 1 month was associated with asthma and wheeze through to 24 years.

CONCLUSION

Lung airflow measurements track from birth into early adulthood, suggesting a permanent and stable airway framework is laid down in the antenatal period. Lower infant airway function is associated with respiratory symptoms into adulthood, indicating the link is clinically important. Antenatal and early life exposures must be addressed in order to maximize airway growth and reduce lifelong respiratory compromise.

Serological survey of Australian native reptiles for exposure to ranavirus

Ranaviruses have been isolated from many ectothermic vertebrates, and serological surveys of both amphibians and reptiles have shown the presence of ranaviral antibodies in a proportion of these populations. An enzyme-linked immunosorbent assay (ELISA) was developed to measure serum antibodies against ranavirus in Australian reptiles. The ELISA was validated with serum from challenge trials with Bohle iridovirus (BIV) in 6 reptilian species. A preliminary sero-survey of northern Queensland riparian reptile fauna (saw-shelled turtles Myuchelys latisternum, Krefft's river turtles Emydura macquarii krefftii, freshwater crocodiles Crocodylus johnstoni, as well as the snakes Boiga irregularis, Dendrelaphis punctulatus, Tropidonophis mairii, Morelia spilota, Liasis childreni and L. fuscus) revealed evidence of past exposure to Bohle iridoviral antigens in part of the population at several locations sampled. Furthermore, in Krefft's river turtles and freshwater crocodiles, a statistically significant trend was apparent for larger reptiles to be more likely to have BIV-reactive sera than smaller individuals. The use of adult tortoise populations as sentinels can assist in monitoring the presence of BIV in northern Australian freshwater streams, and thereby the potential dangers to native fauna from this agent.

A multidisciplinary team (MDT) approach to managing alcohol-dependent patients with comorbid depression in an acute hospital setting

Introduction

Alcohol-dependent patients have a significantly increased risk of depression, contributing a cycle of relapse and attendance at acute hospital services seeking help. Care is often focused on the alcohol dependence treatment with little consideration of concomitant psychiatric disorders.

Aim

To help bridge this gap in care planning and aim toward multidisciplinary long-term support.

Method

We collected data on all patients referred to our alcohol complex patient MDT. We investigated the range of disciplines involved in patient care. We spoke to our patients about why they had chosen to attend hospital. We then developed a referral system to our alcohol MDT where a bespoke pathways of care was developed with all current and future care providers.

Results

Our patients were often being cared for by multiple services, however much of this work was happening in isolation and was at times conflicting. Importantly, the patients were unclear where to go for what, and were utilizing the ED as a fail-safe when they were troubled.

Of 15 patients referred to MDT, 7 (50%) had a diagnosis of depression (DSM-IV). These patients had an average of 5.1 hospital attendances and 2.2 hospital admissions in the 3 months prior to MDT. At 3 months post-MDT, we were able to demonstrate a reduction in hospital admissions and attendances (average 2.2 & 1.4, respectively).

Conclusions

An MDT for alcohol-dependent patients with depression facilitates effective and collaborative working for the benefit of patients and services.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Mosquito cells (C6/36) fail to support the complete replication of Penaeus merguiensis hepandensovirus

Mosquito cell lines (C6/36) were reported in the literature to support the propagation of Penaeus monodon hepandensovirus (PmoHDV). We aim to evaluate the susceptibility and viral propagation of P. merguiensis hepandensovirus (PmeHDV) which is ∼22% different to PmoHDV in Aedes albopictus cell line (C6/36). Cellular changes in the infected cell culture were detected. Vacuole formation was seen in both infected and uninfected cell cultures. The average number of disrupted cellular membranes in the infected cells (presumptive dead cells) was significantly higher than that of uninfected cells at passage two (F=9.749, d.f. 1, 22, p<0.05). Using a proliferation assay, light absorption of infected cells peaked at 2weeks post-infection (O.D.=0.27) but was significantly lower than that of the uninfected groups (O.D.=0.37) (F=6.879, d.f. 1, 94, p<0.05) suggesting hindered cell growth. PCR of the serial passages of the infected cell cultures indicated weak positive results for PmeHDV infection and TaqMan quantitative PCR confirmed that the average number of viral copies declined from 3.8×10⁵ to 5.69×10² copies per μL and the mean of cycle times increased from 19.26 to 27.63. These results are interpreted to mean C6/36 allows the initial stage of PmeHDV replication, but the virus was incapable of using C6/36 for patent replication of its' virions.

Infant lung function predicts asthma persistence and remission in young adults

BACKGROUND AND OBJECTIVE

Asthma in adults is associated with a persistent reduction in lung function from childhood, but this link has not been assessed back to infancy. Reduced infant lung function (ILF), a measure of antenatal and infant lung growth, is associated with asthma into adolescence. Our aim was to assess whether this link persists into adulthood and whether ILF can predict the remission of asthma symptoms in young adults.

METHODS

The study cohort was an unselected full-term birth cohort of 253 subjects enrolled antenatally with lung function assessments at 1, 6 and 12 months (maximum expiratory flow at functional residual capacity, V'maxFRC), and 6, 11, 18 and 24 years (spirometry) of age.

RESULTS

Infants with V'maxFRC in the lowest quartile at 1 month had an OR of 5.1 (95% CI: 2-13, P = 0.001) for asthma at 24 years. Subjects with asthma at 24 years had a mean V'maxFRC at 1 month of 69% predicted (95% CI: 48-90%) versus 110% (95% CI: 101-119%) in non-asthmatic patients (P = 0.001). Subjects with current versus resolved asthma symptoms at 24 years had a mean V'maxFRC at 1 month of 69% predicted (95% CI: 53-84%) versus 105% (88-123%), respectively (P = 0.003). Subjects with current asthma at 24 years had persistently lower lung function from infancy with a mean reduction of 16.2% (95% CI: 8.1-24.3%, P < 0.0001).

CONCLUSION

Reduced lung function in early infancy is predictive of persistent asthma in young adults and a persistent reduction in lung function, suggesting abnormal lung development and growth in utero or very early in life.

Pathogenicity in six Australian reptile species following experimental inoculation with Bohle iridovirus

Ranaviruses are able to infect multiple species of fish, amphibian and reptile, and some strains are capable of interclass transmission. These numerous potential carriers and reservoir species compound efforts to control and contain infections in cultured and wild populations, and a comprehensive knowledge of susceptible species and life stage is necessary to inform such processes. Here we report on the challenge of 6 water-associated reptiles with Bohle iridovirus (BIV) to investigate its potential pathogenicity in common native reptiles of the aquatic and riparian fauna of northern Queensland, Australia. Adult tortoises Elseya latisternum and Emydura krefftii, snakes Boiga irregularis, Dendrelaphis punctulatus and Amphiesma mairii, and yearling crocodiles Crocodylus johnstoni were exposed via intracoelomic inoculation or co-habitation with infected con-specifics, but none were adversely affected by the challenge conditions applied here. Bohle iridovirus was found to be extremely virulent in hatchling tortoises E. latisternum and E. krefftii via intracoelomic challenge, as demonstrated by distinct lesions in multiple organs associated with specific immunohistochemistry staining and a lethal outcome (10/17) of the challenge. Virus was re-isolated from 2/5 E. latisternum, 4/12 E. krefftii and 1/3 brown tree snakes B. irregularis. Focal necrosis, haemorrhage and infiltration of granulocytes were frequently observed histologically in the pancreas, liver and sub-mucosa of the intestine of challenged tortoise hatchlings. Immunohistochemistry demonstrated the presence of ranavirus antigens in the necrotic lesions and in individual cells of the vascular endothelium, the connective tissue and in granulocytes associated with necrosis or present along serosal surfaces. The outcome of this study confirms hatchling tortoises are susceptible to BIV, thereby adding Australian reptiles to the host range of ranaviruses. Additionally, given that BIV was originally isolated from an amphibian, our study provides additional evidence that interclass transmission of ranavirus may occur in the wild.

Induction and characterization of lysogenic bacteriophages from Streptococcus iniae

AIMS

To investigate the presence of prophage in Streptococcus iniae, a highly problematic fish pathogen.

METHODS AND RESULTS

Cross-spotting assays and mitomycin C inductions were conducted to screen for prophage in 48 Strep. iniae isolates. Bacteriophages were characterized by plaque assays, transmission electron microscopy and DNA restriction enzyme digestion. Plaque assays confirmed prophages in 14·6% of isolates. Phages vB_SinS-44, vB_SinS-45, vB_SinS-46 and vB_SinS-48 lysed 78·5% of Strep. iniae isolates and displayed distinctive host ranges. Microscopy revealed virions exhibiting long, non-contractile tails and isometric heads consistent with phages from the family Siphoviridae. Restriction digests revealed genome sizes ranging from 27·5 to 66·3 kbp, with distinct cutting patterns that indicate the presence of related prophages in bacteria isolated from different geographic regions.

CONCLUSIONS

The rate of prophage carriage found is comparably low and induction rates varied between phages. The four characterized Siphoviridae phages have broad host ranges within the Strep. iniae isolates.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is the first description and characterization of lysogenic phages from Strep. iniae. These phages are candidates for research and diagnosis of the bacterium and their identification should accelerate the discovery of lytic phages to be trialled against Strep. iniae infections in fish.

Non-permissive C6/36 cell culture for the Australian isolate of Macrobrachium rosenbergii nodavirus

Macrobrachium rosenbergii nodavirus (MrNV) that causes white tail disease (WTD) is an emerging disease that contributes to serious production losses in Macrobrachium hatcheries worldwide. Mosquito cell lines (C6/36) have been reported to support the growth of MrNV and used to observe the cytopathic effects (CPE) in infected cells. This study determined the susceptibility of C6/36 mosquito cells to the Australian isolate of MrNV in order to use fewer animals in further investigations. Different staining methods were used to observe MrNV viral activity in C6/36 cells. Typical cytopathic effects such as vacuolation and viral inclusion bodies were observed in infected C6/36 cells with H&E and Giemsa staining. With acridine orange, it was easier to detect presumptive MrNV messenger ribonucleic acid in the infected cells. Using neutral red staining to measure mitochondrial activity showed light absorption of infected cells maximized at day 4 (O.D. = 0.6) but was significantly lower (chi-square = 41.265, df = 1, P < 0.05) than control groups (O.D. = 2) which maximized at day 12. Using trypan blue staining to count the number of cells with disrupted cell membranes, the maximum number of presumptively dead cells at day 8 (4 × 10(5)  cells) in infected treatments was higher than the control treatment at day 10 (1.8 × 10(5)  cells). However, TaqMan real-time PCR did not confirm the replication of MrNV in the cells over 14 days. The mean viral copies and mean cycle times of positive samples were stable at 2.07 × 10(4) and 24.12, respectively. Limited evidence of viral replication was observed during four serial passages. This study determined the mortality of the C6/36 cell line to the Australian isolate of MrNV but suggests limited patent replication was occurring. Trying different cell lines or adapting the virus to the C6/36 cells may be necessary to successfully replicate Australian MrNV in cell lines.

The impact of travel distance on the decision to attend for screening for gestational diabetes mellitus

This paper estimates the impact of travel distance on the decision to attend for screening for gestational diabetes mellitus (GDM), controlling for a range of personal, clinical and lifestyle characteristics. The results suggest that women who live further away from a screening site are less likely to attend for screening. In particular, the probability of attending for screening is reduced by 1.8% [95% CI: 1.2% to 2.4%] for every additional 10 kms of travel. This is consistent wth previous research that shows geographic inequalities in access to GDM screening in Ireland. We also find that older women, those with a family history of diabetes, and those who are obese are more likely to accept the screening offer, suggesting that certain higher-risk groups may be either self-selecting into the screening programme or are being targeted by health care professionals through specific initiatives.

Is there a socioeconomic gradient in the prevalence of gestational diabetes mellitus?

Previous studies have shown an association between Type 2 diabetes and lower socioeconomic status. This link is less clear in those with gestational diabetes mellitus (GDM). We test for a socioeconomic gradient in the prevalence of GDM by analysing data on 9,842 pregnant women who were offered testing for GDM in the Atlantic Diabetes in Pregnancy universal screening programme. A bivariate probit model relating GDM prevalence to socioeconomic status was estimated, controlling for variation in screening uptake rates across socioeconomic groups. The estimated increased prevalence of GDM is 8.6% [95% CI 2.7%-12.0%] for women in the lowest socioeconomic group when compared to the highest, suggesting a strong socioeconomic gradient in the prevalence of GDM. This gradient is found to be driven by differences in personal, clinical and lifestyle factors across socioeconomic groups.

Trimester-specific reference intervals for IFCC standardised haemoglobin A(1c): new criterion to diagnose gestational diabetes mellitus (GDM)?

We established trimester-specific reference intervals for IFCC standardised HbA(1c) in 311 non-diabetic Caucasian pregnant women (n = 246) and non-pregnant women (n = 65). A selective screening strategy based on risk factors for gestational diabetes was employed. Pregnancy trimester was defined as trimester 1 (T1, n = 40) up to 12 weeks + 6 days, trimester 2 (T2, n = 106) 13 to 27 weeks + 6 days, trimester 3 (T3, n = 100) > 28 weeks to delivery. The normal HbA(1c) reference interval for Caucasian non-pregnant women was 29-37 mmol/mol (DCCT: 4.8-5.5%), T1: 24-36 mmol/mol (DCCT: 4.3-5.4%), T2: 25-35 mmol/mol (DCCT: 4.4-5.4%), and T3: 28-39 mmol/mol (DCCT: 4.7-5.7%). HbA(1c) was significantly decreased in trimesters 1 (P < 0.01) and 2 (P < 0.001) compared to non-pregnant women. Retrospective application of selective screening to Caucasian women of the Atlantic DIP cohort determined that 5,208 met the criteria. 945 of those women (18.1%) were diagnosed with Gestational Diabetes Mellitus (GDM) using the International Association of Diabetes and Pregnancy Study Groups (IADPSG) glucose concentration thresholds. HbA(1c) measurement within 2 weeks of the diagnostic Oral Glucose Tolerance Test (OGTT) was available in 622 of 945 (66%). Applying the decision threshold for T2: HbA(1c) > 35 mmol/mol (DCCT > 5.4%) identified 287 of 622 (46%) of those with GDM. HbA(1c) measurement in T2 (13 to 27 weeks) should be included in the diagnostic armamentarium for GDM. This would reduce the need for diagnostic OGTT in a significant number of women.

Psychological stress associated with diabetes during pregnancy: a pilot study

Gestational Diabetes Mellitus (GDM) affects approximately 12% of women. The impact of a diagnosis of GDM may lead to increased stress in pregnancy due to the demands of adherence to a treatment regimen and maternal concern about adverse outcomes for the mother and baby. We examined the psychosocial profile of 25 women with gestational diabetes mellitus (GDM) and compared them to 25 non-diabetic pregnant women. Measures administered included the Pregnancy Experiences Scale (PES), the Depression, Anxiety Stress Scale (DASS), the Problem Areas in Diabetes Scale (PAID-5) and the Perceived Social Support Scale (PSSS). The GDM group reported a significantly greater ratio of pregnancy 'hassles' to pregnancy 'uplifts'. The GDM group also had a significantly higher Depression score and were twice as likely to score above the cut-off for possible depression. Elevated levels of diabetes-related distress were found in 40% of women with GDM. In addition, the GDM group reported less social support from outside the family. Our preliminary study indicates that the experience of GDM appears to be associated with increased psychological distress in comparison to the experience of non-diabetic pregnant women. This may indicate the need for psychological screening in GDM and the provision of psychological support in some cases.

Injection of Acanthaster planci with thiosulfate-citrate-bile-sucrose agar (TCBS). II. Histopathological changes

We assessed histological changes in the tissues of the crown-of-thorns starfish Acanthaster planci (COTS) after injection of thiosulfate-citrate-bile-sucrose agar (TCBS) which was used as a disease inducer (potential outbreak control method), by conventional and scanning electron microscopy. Digestive glands were processed and stained with hematoxylin and eosin to describe the histological architecture of the intestinal epithelium. Subsequently comparison of healthy versus infected tissues and Gram stains were carried out to confirm bacterial occurrence on infected tissues, characterize the structural changes induced by bacterial communities in COTS tissues, and to determine if the histopathological changes of intestinal tissues were consistent with vibrio infection. TCBS injections induced marked epithelial desquamation, hypertrophy and hypersecretion of glandular cells, epithelial cell destruction, pyknosis, reduction of thickness and disorganization of connective tissue and associated nerve plexus, presence of bacterial colonies, irregular eosinophilic foci in glandular cells, brush border disruption, atrophy and detachment of intestinal microvilli and cell debris in the lumen. All these changes were attributed to a fulminating systemic dysbiosis and were consistent with vibrio infections.

Injection of Acanthaster planci with thiosulfate-citrate-bile-sucrose agar (TCBS). I. Disease induction

This is the first report of the successful induction of a transmissible disease in the coral-eating crown-of-thorns starfish Acanthaster planci (COTS). Injection of thiosulfate-citrate-bile-sucrose agar (TCBS) culture medium into COTS induced a disease characterized by discoloured and necrotic skin, ulcerations, loss of body turgor, accumulation of colourless mucus on many spines especially at their tip, and loss of spines. Blisters on the dorsal integument broke through the skin surface and resulted in large, open sores that exposed the internal organs. Oedema and reddened digestive tissues and destruction of connective fibers were common. Moreover, healthy COTS in contact with these infected animals also displayed signs of disease and died within 24 h. TCBS induced 100% mortality in injected starfish. There was no introduction of new pathogens into the marine environment. TCBS promoted the growth of COTS' naturally occurring Vibrionales to high densities with subsequent symbiont imbalance followed by disease and death.

Refined identification of Vibrio bacterial flora from Acanthasther planci based on biochemical profiling and analysis of housekeeping genes

We used a polyphasic approach for precise identification of bacterial flora (Vibrionaceae) isolated from crown-of-thorns starfish (COTS) from Lizard Island (Great Barrier Reef, Australia) and Guam (U.S.A., Western Pacific Ocean). Previous 16S rRNA gene phylogenetic analysis was useful to allocate and identify isolates within the Photobacterium, Splendidus and Harveyi clades but failed in the identification of Vibrio harveyi-like isolates. Species of the V harveyi group have almost indistinguishable phenotypes and genotypes, and thus, identification by standard biochemical tests and 16S rRNA gene analysis is commonly inaccurate. Biochemical profiling and sequence analysis of additional topA and mreB housekeeping genes were carried out for definitive identification of 19 bacterial isolates recovered from sick and wild COTS. For 8 isolates, biochemical profiles and topA and mreB gene sequence alignments with the closest relatives (GenBank) confirmed previous 16S rRNA-based identification: V. fortis and Photobacterium eurosenbergii species (from wild COTS), and V natriegens (from diseased COTS). Further phylogenetic analysis based on topA and mreB concatenated sequences served to identify the remaining 11 V harveyi-like isolates: V. owensii and V. rotiferianus (from wild COTS), and V. owensii, V. rotiferianus, and V. harveyi (from diseased COTS). This study further confirms the reliability of topA-mreB gene sequence analysis for identification of these close species, and it reveals a wider distribution range of the potentially pathogenic V. harveyi group.

The effect of Penaeus merguiensis densovirus on Penaeus merguiensis production in Queensland, Australia

Penaeus merguiensis densovirus (PmergDNV) is currently present on several Queensland prawn farms culturing Penaeus merguiensis. Densoviruses have been linked to mortality and stunting that has caused significant financial loss to prawn farms in Asia. A histopathological study for PmergDNV was initially undertaken to compare broodstock to grow out factors from 60 broodstock animals from each of 22 ponds. There was a significant negative correlation (r = -0.61) between the number of animals with PmergDNV lesions and healthy animals. Furthermore, a higher number of septic hepatopancreatic tubules was correlated (r = 0.48) to high PmergDNV loads. Hence, a polymerase chain reaction analysis of 10-day-old post-larvae (PL) was conducted to determine whether PmergDNV infection was resulting in production losses. An attributable risk analysis of PL from 190 ponds over a 2-year period revealed that 28-29% of ponds with below average survival will have at least average survival following the removal of or decreased levels of PmergDNV. P. merguiensis culture facilities in Queensland should have at least a 14.5% increase in production, equating to an increase of $2.25 million within the first year alone, following the removal or reduction of PmergDNV in their ponds. Hence, focussing efforts on prevention, better management practices and maintaining healthy stock should be of top priority.

Gill-associated virus and its association with decreased production of Penaeus monodon in Australian prawn farms

Gill-associated virus (GAV) was found to be associated with decreased prawn, Penaeus monodon, production when prawns from three farms (n = 45 ponds, 1800 prawns) were monitored for GAV over the production season using a graded RT-nPCR. The grading system used was a visualization of either the outer or inner nested PCR products. Prevalence and loading of GAV were associated with disease severity. Ponds with a higher initial prevalence and a larger increase in GAV load over the production period suffered disease outbreaks. Ponds with low initial prevalence of GAV but a larger increase in prevalence and large increase in load over the production period suffered chronic disease with no disease outbreak identified, yet low production. However, the ponds with moderate to low initial prevalence of GAV with a low increase in prevalence and load of GAV over the production period incurred no disease outbreak and comparatively high production. Ponds with GAV prevalence greater than 75% at 1 month post-stocking should be considered for termination as they have a high probability (95%) of having a disease outbreak. Emergency harvest when a disease outbreak occurs will significantly limit mortality losses.

Insight into the lymphoid organ of penaeid prawns: a review

In crustacea, the lymphoid organ (LO) is found exclusively in penaeid prawns. Other crustaceans such as crabs, lobsters and crayfish do not possess lymphoid organs. Many scientists believe that the lymphoid organ is involved in defence against invading pathogens. The discovery of immune-related genes with the LO confirms some cells have immunological roles even though these genes might be from the haemocytes within this organ. The formation of the lymphoid organ spheroid (LOS) cells has been observed in many naturally or experimentally infected penaeid prawns with viral diseases. It has been suggested that these spheroid cells constitute a major site of viral degradation. The origin and elimination mechanism of the spheroids has been debated in a number of publications. It is most likely that this cell type is produced from exocytosed granular haemocytes and eliminated to the environment rather than in situ destruction via necrosis or apoptosis.

Isolation of lytic bacteriophage against Vibrio harveyi

AIMS

The isolation of lytic bacteriophage of Vibrio harveyi with potential for phage therapy of bacterial pathogens of phyllosoma larvae from the tropical rock lobster Panulirus ornatus.

METHODS AND RESULTS

Water samples from discharge channels and grow-out ponds of a prawn farm in northeastern Australia were enriched for 24 h in a broth containing four V. harveyi strains. The bacteriophage-enriched filtrates were spotted onto bacterial lawns demonstrating that the bacteriophage host range for the samples included strains of V. harveyi, Vibrio campbellii, Vibrio rotiferianus, Vibrio parahaemolyticus and Vibrio proteolyticus. Bacteriophage were isolated from eight enriched samples through triple plaque purification. The host range of purified phage included V. harveyi, V. campbellii, V. rotiferianus and V. parahaemolyticus. Transmission electron microscope examination revealed that six purified phage belonged to the family Siphoviridae, whilst two belonged to the family Myoviridae. The Myoviridae appeared to induce bacteriocin production in a limited number of host bacterial strains, suggesting that they were lysogenic rather than lytic. A purified Siphoviridae phage could delay the entry of a broth culture of V. harveyi strain 12 into exponential growth, but could not prevent the overall growth of the bacterial strain.

CONCLUSIONS

Bacteriophage with lytic activity against V. harveyi were isolated from prawn farm samples. Purified phage of the family Siphoviridae had a clear lytic ability and no apparent transducing properties, indicating they are appropriate for phage therapy. Phage resistance is potentially a major constraint to the use of phage therapy in aquaculture as bacteria are not completely eliminated.

SIGNIFICANCE AND IMPACT OF THE STUDY

Phage therapy is emerging as a potential antibacterial agent that can be used to control pathogenic bacteria in aquaculture systems. The development of phage therapy for aquaculture requires initial isolation and determination of the bacteriophage host range, with subsequent creation of suitable phage cocktails.

Evidence for the classification of a crayfish pathogen as a member of the genus Coxiella

AIMS

The study aimed to provide characterization of a potential new species of Coxiella, identified following a series of outbreaks of disease in Australian native freshwater crayfish.

METHODS AND RESULTS

PCR primers designed for amplification of Coxiella burnetii genes including 16S rDNA, com1 and sodB were used to amplify homologues in the Coxiella-like crayfish pathogen. Products were then cloned and sequenced. The organism demonstrated a high degree of sequence homology in the highly conserved 16S rDNA (96%) and sodB (99%) genes, as well as the Coxiella sp. specific com1 (100%) gene. Regions flanking the sodB coding sequence demonstrated homology to C. burnetii antioxidant AhpC/Tsa family protein and dihydrodipicolinate reductase gene.

CONCLUSIONS

The degree of homology between the genes selected and flanking regions suggested the two organisms were sufficiently closely related to belong to the same genus.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study provided evidence for a potential new species in the currently monospecific genus Coxiella, with the only described member being C. burnetii, a category B biological warfare agent.

Sensitivity and specificity of current diagnostic tests for gill-associated virus in Penaeus monodon

This study reports the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy between a reverse transcriptase-nested polymerase chain reaction (RT-nPCR) and an enzyme-linked immunosorbent assay (ELISA) for the detection of gill-associated virus (GAV) from a sample of 120 Penaeus monodon. Subsequently, the same comparisons were applied to the ELISA and haemagglutination (HA) assays for detection of GAV from a second 120 prawns. The optical density (OD) or dilution cut-off point had a direct influence on the tested parameters. The cut-off OD of 0.5-0.6 with the ELISA produced a sensitivity of 98% compared with RT-nPCR. However, these OD produced the lowest accuracy (85.8% and 86.7%, respectively). The OD cut off of 0.75 resulted in the highest accuracy (91.7%) and NPV (81.3%) while it had the second highest sensitivity (97%) and PPV (93.3%). However, the OD cut off of 0.9 had the highest specificity (80%). With regards to HA, the titre cut off at 8 resulted in the highest sensitivity, specificity and NPV (94%, 100% and 100%, respectively) compared with the ELISA, while the HA titre of 16 gave the highest accuracy (73%) and the second highest specificity (75%). A HA titre of 64 gave the highest PPV (81%). Using the RT-nPCR as the gold standard, the ELISA had an accuracy of 91.7% when using a cut off >0.75 as a positive result. When compared with the ELISA, the HA had an accuracy of 73% when using an HA titre cut off greater than 16 as a positive result. These results indicate that alternative tests for GAV (ELISA and HA) can be used to explore multiple questions about the disease status of P. monodon stocks in a cost-effective manner.