[Show abstract][Hide abstract] ABSTRACT: Purpose:
Research has not convincingly demonstrated the utility of saliva secretory Immunoglobulin-A (SIgA) as a biomarker of upper-respiratory-tract-infection (URTI) risk and disagreement exists about the influence of heavy exercise ('open-window-theory') and dehydration on saliva SIgA. Prompted by the search for viable alternatives, we compared the utility of tear and saliva SIgA to predict URTI prospectively (study-one) and assessed the influence of exercise (study-two) and dehydration (study-three) using a repeated-measures-crossover design.
In study-one, forty subjects were recruited during the common-cold season. Subjects provided tear and saliva samples weekly and recorded upper-respiratory-symptoms (URS) daily for 3-weeks. RT-PCR confirmed common-cold pathogens in 9 of 11 subjects reporting URS (82%). Predictive utility of tear and saliva SIgA was explored by comparing healthy samples with those collected the week pre-URS. In study-two, thirteen subjects performed a 2-hour run at 65% VO2peak. In study-three, thirteen subjects performed exercise-heat-stress to 3% body-mass-loss followed by overnight fluid restriction.
Tear SIgA concentration and secretion rate were 48% and 51% lower respectively during URTI and 34% and 46% lower the week pre-URS (P<0.05) but saliva SIgA remained unchanged. URS risk the following week increased 9-fold (95% CI: 1.7 to 48) when tear SIgA secretion rate <5.5 μg[BULLET OPERATOR]min and 6-fold (95% CI: 1.2 to 29) when tear SIgA secretion rate decreased >30%. Tear SIgA secretion rate >5.5 μg[BULLET OPERATOR]min or no decrease >30% predicted subjects free of URS in >80% of cases. Tear SIgA concentration decreased post-exercise (-57%: P<0.05) in line with the 'open-window-theory' but was unaffected by dehydration. Saliva flow rate decreased and saliva SIgA concentration increased post-exercise and during dehydration (P<0.05).
Tear SIgA has utility as a non-invasive biomarker of mucosal immunity and common-cold risk.
Medicine and science in sports and exercise 10/2015; DOI:10.1249/MSS.0000000000000801 · 3.98 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Importance:
Most respiratory viruses target airway epithelium for infection and replication, which is central to causing disease. However, for most human viruses we have a poor understanding of their interactions with human airway epithelium. Respiratory syncytial virus (RSV) is the most important viral pathogen of young infants. To help understand RSV interactions with pediatric airway epithelium, we previously developed 3-D primary cell cultures from infant bronchial epithelium that reproduce several hallmarks of RSV infection in infants, indicating that they represent authentic surrogates of RSV infection in infants. We found that RSV induced a potent antiviral state in these cultures and that type III interferon (IL-29) was involved. Indeed, our data suggest that IL-29 has potential to prevent RSV disease. However, we also demonstrated that RSV efficiently circumvents this antiviral immune response and identified mechanisms by which this may occur. Our study provides new insights into RSV interaction with pediatric airway epithelium.
Journal of Virology 09/2015; 89(24):JVI.02119-15. DOI:10.1128/JVI.02119-15 · 4.44 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Inflammation of the urethra defined by an excess of polymorphonuclear leukocytes in the absence of sexually transmitted Chlamydia trachomatis and Neisseria gonorrhoeae is called non-chlamydial non-gonococcal urethritis (NCNGU). Although Mycoplasma genitalium is now recognised as causing a sexually transmitted infection, the clinical significance of the other Mollicute species is less clear. This study used specific real-time quantitative polymerase chain reaction assays to detect and quantify four Mollicute species M. genitalium, M. hominis, Ureaplasma urealyticum and U. parvum in urine specimens from males with and without NCNGU. A total of 165 urine specimens from male patients attending genitourinary medicine clinic were eligible for the study, with microscopy-confirmed (≥5 polymorphonuclear leukocytes in urethral swab) NCNGU in 75 (45.5%) males and non-confirmed NCNGU in 90 (54.5%) males. Chi-squared statistical analysis indicated a significantly higher prevalence of U. parvum (17.3% vs. 5.6%; p = 0.03) and M. genitalium (12% vs. 0%; p < 0.001) in NCNGU. In a subset analysis, M. genitalium was also significantly (p = 0.03) higher in men who have sex with men (MSM; 13.5%) compared to non-MSM (3.1%). No significant associations were reported for U. urealyticum and M. hominis. In conclusion, this study supports a clinically significant role in NGNCU for both U. parvum and M. genitalium.
International Journal of STD & AIDS 09/2015; DOI:10.1177/0956462415597620 · 1.05 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Using a C. difficile glutamate dehydrogenase (GDH) immunoassay and a sensitive C. difficile toxin A/B immunoassay, human stool specimens from patients with diarrhoea (n=1085) were classified as either GDH-positive / toxin-negative, or GDH-positive / toxin positive. 528/725 (73%) of the GDH-positive / toxin-negative specimens contained viable C. difficile, and 433/528 (82%) of these C. difficile isolates were PCR positive for the toxin gene pathogenicity locus. Overall, 867/1078 (80%) of the GDH-positive specimens contained viable C. difficile, and 433/725 (60%) of the GDH-positive / toxin-negative specimens contained a toxigenic C. difficile strain. The diversity of toxigenic C. difficile ribotypes isolated from toxin-negative specimens (n=433) and toxin-positive specimens (n=339) was significantly different (p<0.0001). Specifically, presence of ribotype 078 strains was very strongly associated (p<0.0001) with detection of toxin in clinical specimens using a sensitive toxin immunoassay. Specimens positive for ribotype 078 were almost twice as likely to be toxin positive as opposed to toxin negative (RR=1.90, 95% CI 1.64-2.19). In contrast, other circulating ribotypes were seen with similar frequency in specimens with and without detectable toxin. This supports the view that ribotype 078 strains may be more virulent than other common ribotypes in terms of toxin production.
Journal of Medical Microbiology 09/2015; DOI:10.1099/jmm.0.000165 · 2.25 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Objective:
To compare the use of a generic molecular assay to 'standard' investigations used to assist the diagnosis of late onset bacterial sepsis in very low birth weight infants (VLBW, <1500g).
VLBW infants, greater than 48 hours of age, who were clinically suspected to have sepsis were investigated using standard tests (full blood count, C-reactive protein (at presentation) and blood culture), in addition, blood was taken for a universal molecular assay (16S rRNA reverse transcriptase PCR) for comparison. Clinical data were recorded during the suspected infection episode. A validated sepsis score (NEO-KISS) was used to retrospectively determine the presence of sepsis (independent of blood culture). The performance of each of the tests were compared by sensitivity, specificity, positive/negative likihood ratios (+/-LR) and postive/negative predictive values (PPV/NPV).
Sixty-five babies with suspected clinical sepsis were prospectively included. The performance indicators are presented with 95% confidence limits. For the detection of bacteria, blood culture had sensitivity of 0.57 (0.34-0.78), specificity of 0.45 (0.30-0.61); +LR of 1.05 (0.66-1.66) and-LR of 0.94 (0.52-1.7); PPV of 33.3 (18.56-50.97) and NPV of 68.97 (49.17-87.72). Serum CRP had sensitivity of 0.92 (0.64-1) and specificity of 0.36 (0.17-0.59); +LR of 1.45 (1-2.1) and-LR of 0.21 (0.03-1.5); PPV of 44.46 (26.6-66.6) and NPV of 88.9 (51.8-99.7). The universal molecular assay had sensitivity of 0.76 (0.53-0.92), specificity of 0.95 (0.85-0.99); +LR of 16.8 (4.2-66.3) and-LR of 0.25 (0.1-0.5); PPV of 88.9 (65.3-98.6) and NPV of 89.4 (76.9-96.5).
In VLBW infants this universal molecular assay performed better in the diagnosis of late onset sepsis (LOS) than blood culture and CRP. Further development is required to explore and improve the performance of the assay in real-time diagnosis.
PLoS ONE 08/2015; 10(8):e0136472. DOI:10.1371/journal.pone.0136472 · 3.23 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Gardnerella vaginalis is a Gram variable anaerobic bacterium present in 100% of women with bacterial vaginosis (BV). BV is a complex polymicrobial condition with no single causative agent. The current laboratory detection method for BV relies on a Gram stain Nugent score to estimate the quantity of different bacterial morphotypes in the vaginal micro-flora. While the Nugent score can distinguish between women with and without BV, a significant proportion categorise as intermediate, which fails to differentiate a normal from an abnormal vaginal micro-flora. A singleplex G.vaginalis TaqMan® real-time quantitative Polymerase Chain Reaction (qPCR) assay was developed compared against the 'gold standard' Nugent score. Detection and quantification of G.vaginalis was performed on vaginal specimens with positive, negative and intermediate Nugent scores. The G.vaginalis assay demonstrated high analytical specificity against a broad microbial panel and analytical sensitivity down to 3.1x104 copies per ml. There was a significantly higher G.vaginalis load in women with BV compared to intermediate and non-BV women (p value=5.1x10-14). All Nugent scores in keeping with BV had qPCR loads of ≥ 107 copies per ml. Amongst the 24 undefined women (11.8%) in the study with an intermediate flora, 14 (58.3%) had a G.vaginalis load ≥107 copies per ml. In this study a threshold of 107 copies per ml had positive and negative predictive values of 57.1% and 100% for BV; the high qPCR loads amongst the Intermediate Nugent scores suggest the need for a new approach in classifying BV and the potential for qPCR to play a role.
Journal of Medical Microbiology 06/2015; 64(9). DOI:10.1099/jmm.0.000118 · 2.25 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Long-term health-related quality-of-life (HRQL) outcomes have not been widely reported in the treatment of achalasia. The aims of this study were to examine long-term disease-specific and general HRQL in achalasia patients using a population-based case-control method, and to assess HRQL between treatment interventions. Manometrically diagnosed achalasia cases (n = 120) were identified and matched with controls (n = 115) using a population-based approach. Participants completed general (SF-12) and disease-specific (Achalasia Severity Questionnaire [ASQ]) HRQL questionnaires, as appropriate, in a structured interview. Mean composite scores for SF-12 (Mental Component Summary score [MCS-12] and Physical Component Summary score [PCS-12]) and ASQ were compared between cases and controls, or between intervention groups, using an independent t-test. Adjusted mean differences in HRQL scores were evaluated using a linear regression model. Achalasia cases were treated with a Heller's myotomy (n = 43), pneumatic dilatation (n = 44), or both modalities (n = 33). The median time from last treatment to HRQL assessment was 5.7 years (interquartile range 2.4-11.5). Comparing achalasia patients with controls, PCS-12 was significantly worse (40.9 vs. 44.2, P = 0.01), but MCS-12 was similar. However, both PCS-12 (39.9 vs. 44.2, P = 0.03) and MCS-12 (46.7 vs. 53.5, P = 0.004) were significantly impaired in those requiring dual treatment compared with controls. Overall however, there was no difference in adjusted HRQL between patients treated with Heller's myotomy, pneumatic dilatation or both treatment modalities. In summary, despite treatment achalasia patients have significantly worse long-term physical HRQL compared with population controls. No HRQL differences were observed between the treatment modalities to suggest a benefit of one treatment over another.
Gut 06/2015; 64(Suppl 1):A475.2-A475. DOI:10.1136/gutjnl-2015-309861.1040 · 14.66 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Background:
Approximately 5-6% of all infective episodes in neonatal intensive care unit (NICU) are of viral origin. Previous studies suggest that human parechovirus (HPeV) infection presents most commonly in term infants, as a sepsis-like syndrome in which meningoencephalitis is prominent. Our aim was to study the infection rate and associated features of HPeV.
Blood samples were taken from NICU babies older than 48 hours, who were being investigated for late onset sepsis. Clinical and laboratory data were collected at the time of the suspected sepsis episode. Samples were tested using universal primers and probe directed at the 5'-untranslated region of the HPeV genome by reverse transcriptase polymerase chain reaction (RT-PCR). Results were confirmed by electrophoresis and DNA sequencing.
HPeV was detected in 11 of 84 samples (13%). These infants had a mean [interquartile range (IQR)] gestational age of 28.9 (26.9-30.6) weeks and mean birth weight of 1.26 (SD = 0.72) kg. The median day of presentation was 16 (IQR: 11-27). These characteristics were similar to the infants without positive viral detection. Six infants presented with respiratory signs. One infant presented with signs of meningitis. Six of the 11 episodes of HPeV infection occurred during the winter months (December to February). No HPeV positive infants had abnormal findings on their 28-day cranial ultrasound examination.
We found an HPeV infection rate of 13% in infants being tested for late onset sepsis. HPeV should be considered as a possible cause of sepsis-like symptoms in preterm infants.
[Show abstract][Hide abstract] ABSTRACT: Norovirus (NoV) gastroenteritis occurs in all age groups and is the most common cause of gastroenteritis in the community. However, detection methods and rates vary widely, and few data are available to compare these, particularly in Ireland. Detection of noroviruses through antigen and molecular-based strategies was carried out on 135 suspected NoV-positive samples, collected over the course of three NoV outbreaks, from 2002 to 2006, in the southern region of Ireland. A commercially available ELISA and a panel of six primer sets were evaluated to determine their suitability for NoV detection in Irish clinical samples. The key findings of this study were the detection of both GGI and GGII noroviruses by ELISA, but the detection of only GGII noroviruses by RT-PCR. In addition to this, a variation in the levels of detection from 9.4 % to 17.3 % was observed for conventional PCR assays, while a detection rate of 46.3 % was observed for the real-time PCR assay. A proportion (17.8 %) of samples were found to be negative by all detection strategies, suggesting the possibility of reporting false positives for these samples or low-copy positives that do not often repeat. Sequencing information from selected samples also revealed nucleotide polymorphisms, compromising efficient primer binding in the case of one primer pairing. Phylogenetic analysis of the partial polymerase gene identified NoV GII.4 as the dominant genotype, in accordance with previous NoV studies in Ireland. Investigating the NoV diversity of the circulating strains and the dynamics of strain replacement is important to better assess the efficacy of future NoV vaccines and to facilitate the early detection of changes in circulating NoV strains.
Archives of Virology 01/2014; 159(7). DOI:10.1007/s00705-014-1987-5 · 2.39 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Respiratory syncytial virus (RSV) is a major pathogen that primarily infects airway epithelium. Most infants suffer mild upper respiratory tract (URT) symptoms, while approximately one third progress to lower respiratory tract (LRT) involvement. Despite the ubiquity of URT infection, little is known about the relative cytopathogenesis of RSV infection in infant URT and LRT.
This study aimed to compare RSV cytopathogenesis in nasal- and bronchial-derived epithelium from the same individuals using novel models derived from well-differentiated primary pediatric nasal (WD-PNECs) and bronchial epithelial cells (WD-PBECs).
WD-PNECs and WD-PBECs were generated from nasal and bronchial brushes, respectively, and mock-infected or infected with RSV BT2a. RSV tropism, infectivity, cytopathology, growth kinetics, cell sloughing, apoptosis, and cytokine/chemokine responses were determined.
RSV infection in both cultures was restricted to apical ciliated cells and occasional non-ciliated cells but not goblet cells. It did not cause obvious cytopathology. Infection resulted in apical release of progeny virus, increased apical cell sloughing, apoptosis and occasional syncytia. RSV growth kinetics and peak titers were higher in WD-PBECs, coincident with higher ciliated cell contents, cell sloughing and slightly compromised tight junctions. However, pro-inflammatory chemokine responses were similar for both cultures. Also, lambda interferons, especially IL-29, were induced by RSV infection.
RSV induced remarkably similar, albeit quantitatively lower, cytopathogenesis and pro-inflammatory responses in WD-PNECs compared to WD-PBECs that reproduce many hallmarks of RSV pathogenesis in infants. WD-PNECs may provide an authentic surrogate model with which to study RSV cytopathogenesis in infant airway epithelium.
American Journal of Respiratory and Critical Care Medicine 08/2013; 188(7). DOI:10.1164/rccm.201304-0750OC · 13.00 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: P jirovecii causes Pneumocystis pneumonia (PCP), a severe opportunistic infection in immunosuppressed patients with both person to person airborne transmission and environmental transmission important routes of infection. An increasing incidence of P. jirovecii in Northern Ireland prompted a detailed epidemiological and molecular review including enhanced surveillance on all lower respiratory specimens. Genotyping of these P. jirovecii positive specimens was undertaken using Multiple Locus Sequence Typing (MLST) targeting known variable regions of the P. jirovecii genome (Hauser et al., 1997). Multiple circulating types were found amongst all patient categories. However a predominance of one MLST type was found in a P. jirovecii outbreak amongst the renal transplant population. Our results demonstrate the diversity of P. jirovecii strains among the local immunosuppressed cohort and highlight the importance of genotyping in the investigation of common sources of P. jirovecii amongst immunosuppressed patients.
Journal of Medical Microbiology 05/2013; 62(Pt_8). DOI:10.1099/jmm.0.057794-0 · 2.25 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Background:
Paper-based diaries and self-report of symptom worsening in COPD may lead to underdetection of exacerbations. Epidemiologically, COPD exacerbations exhibit seasonal patterns peaking at year-end. We examined whether the use of a BlackBerry-based daily symptom diary would detect 95% or more of exacerbations and enable characterization of seasonal differences among them.
Fifty participants with GOLD (Global Initiative for Chronic Obstructive Lung Disease) stage I to IV COPD began a community-based study in December 2007. Another 30 began in December 2008. Participants transmitted daily symptom diaries using a BlackBerry. Alerts were triggered when symptom changes, missed diary transmissions, or medical care for a respiratory problem occurred. Participant encounters were initiated if COPD exacerbations were suspected. Participants used their BlackBerrys to report returns to normal breathing.
Participants transmitted 99.9% of 28,514 possible daily diaries. All 191 (2.5/participant-year) COPD exacerbations meeting Anthonisen criteria were detected. During 148 of the 191 exacerbations (78%, 1.97/participant-year), patients were hospitalized and/or ordered prednisone, an antibiotic, or both. Respiratory viruses were detected in 78 of the 191 exacerbations (41%). Those coinciding with a respiratory viral infection averaged 12.0 days, and those without averaged 8.9 days (P < .04), with no difference in Anthonisen score. Respiratory symptom scores before exacerbations and after normal breathing return showed no differences. Exacerbations were more frequent during the Christmas period than the rest of the year but were not more frequent than in the rest of winter alone.
Smartphone-based collection of COPD symptom diaries enables near-complete identification of exacerbations at inception. Exacerbation rates in the Christmas season do not reach levels that necessitate changes in disease management.
[Show abstract][Hide abstract] ABSTRACT: In Europe fetal loss due to parvovirus B19 (B19V) is under-reported and a poorly addressed occupational risk to pregnant women. This is exemplified internationally, where it was unmentioned in the last 2 ECDC annual surveillance reports or its 2009 special report on infections in pregnancy. To assess this potential for under estimating B19V fetal loss in pregnancy, we undertook a systematic review of practice in Northern Ireland in the management and reporting of B19V infections over a 12 month period of heightened transmission, 1 of 6 observed in a span of 9 years. Pregnant and non-pregnant women presented with symptomatic infection in 24% and 93% of confirmed B19V infections respectively, with no difference in viral loads. There was under investigation of viral causes of fetal loss, with only 143/2739 (5%) tested for B19V, and a failure to follow-up most non-immune women tested following rash contact. Occupational exposure was recorded in 31/60 (51.6%) pregnancies audited following rash exposure, the majority teachers or day care workers. Against a background seroprevalence of 66.5% immunity in women of child-bearing years, two patterns of infection were identified. Firstly, pregnant women investigated for a rash or exposure to slapped cheek syndrome, where an infection incidence of 18% was observed, resulted in 42 confirmed infections, all proceeding to healthy term deliveries. Secondly, pregnant women with unsuspected infection had 6 cases of confirmed B19V fetal loss, including 4 of 22 (18%) diagnosed at autopsy, of which 3 were non-hydropic. While many studies have reported B19V fetal loss in pregnancy, there are no robust public health surveillance figures to draw on. That all 6 confirmed fetal losses came from the small number of miscarriages / stillbirths investigated, 143 out of 2739, suggests inadequate follow-up of those pregnancies where B19V related fetal loss may be most common and supports the need for enhanced surveillance pilots to address this significant gap in public health knowledge.
Journal of Medical Microbiology 09/2012; 62(Pt_1). DOI:10.1099/jmm.0.046714-0 · 2.25 Impact Factor