Adenovirus infection after pediatric bone marrow transplantation: is treatment always necessary?

BACKGROUND: Adenovirus infections are associated with significant rates of morbidity and mortality among children after bone marrow transplantation (BMT). Many transplantation units use molecular virological methods, such as polymerase chain reaction (PCR), for surveillance for adenovirus infection and give preemptive antiviral therapy to children with evidence of disseminated adenovirus infection. This treatment strategy has never been evaluated in clinical trials. METHODS: We retrospectively tested blood samples obtained from a cohort of children who had undergone BMT before the introduction of regular weekly surveillance for adenovirus infection. A total of 273 samples collected from 26 patients between May 1998 and June 2002 were tested for adenovirus infection by quantitative PCR. Virus load was quantified for each sample yielding positive test results, and the clinical notes and virological records of each child were reviewed. RESULTS: Evidence of adenovirus infection was found in 11 children (42%), 7 of whom had not previously had positive test results. Receipt of T cell-depleted transplants was associated with a significantly higher incidence of adenovirus infection during the posttransplantation period. The 2 children who died from adenovirus disease developed infection within 2 weeks after transplantation, and both had very low absolute lymphocyte counts at the time of diagnosis. Seven of 11 children with blood samples that were found to be positive for adenovirus by PCR cleared the virus without antiviral therapy. CONCLUSIONS: Surveillance for adenovirus by PCR is better than symptomatic testing for detecting adenovirus infection. Antiviral therapy may not be necessary for all children who develop adenovirus viremia after BMT.

Polymerase chain reaction in the management of disseminated adenovirus infection after stem cell transplantation.

We report a 20-month-old child with disseminated adenovirus infection after a haploidentical T cell-depleted stem cell transplantation. This case demonstrates the value of polymerase chain reaction surveillance for early detection of adenovirus infection and the role of quantitative polymerase chain reaction for monitoring antiviral therapy. It also emphasizes the importance of T cell immunity in controlling disseminated adenovirus infection after stem cell transplantation.

Influenza A community-acquired pneumonia in East London infants and young children.

BACKGROUND: Community-acquired pneumonia (CAP) is common in young children, but there are few data in Europe on influenza A virus as a cause of childhood CAP. The aim of this study was to determine the relative contributions of different etiologic agents to CAP in children. METHODS: This was a 6-month prospective study of pediatric accident and emergency and general practice consultations with a diagnosis of CAP. Nasopharyngeal aspirates for viral immunofluorescence and PCR studies and blood cultures for bacterial studies were taken from 51 children with symptoms, signs and chest radiographic features that satisfied a diagnosis of pneumonia. RESULTS: An etiologic agent was isolated from 25 patients (49%). A viral cause was identified in 22 patients (43%), and influenza A virus and respiratory syncytial virus (RSV) were detected in 16 and 18% of all cases, respectively. Only four patients (8%) had a positive bacterial blood culture; three had Streptococcus pneumoniae and one had Neisseria meningitidis W135. Mycoplasma pneumoniae was detected in 2 children, and mixed infections were detected in 5 (10%). The use of viral PCR increased the detection rate of influenza A virus by 100%. CONCLUSION: Influenza A virus caused more than one-third of all viral CAP cases, a rate comparable with that of RSV CAP. Viral PCR doubled the diagnostic yield of influenza A virus. The clinical burden of influenza A CAP was comparable with that of RSV CAP, as measured by the duration of fever, hospital stay and total duration of illness.

The distribution of cagA and dupA genes in Helicobacter pylori strains in Kurdistan region, northern Iraq.

BACKGROUND AND OBJECTIVES: Helicobacter pylori is a Gram negative bacteria that causes peptic ulceration and gastric adenocarcinoma. H pylori virulence factors, such as cagA and dupA, are important to study in populations as they contribute to disease risk. This study aimed to look at the distribution of the cagA and dupA genes in H pylori strains isolated from patients suffering from gastroduodenal diseases in Kurdistan region, Iraq. DESIGN AND SETTINGS: A cross-sectional study conducted between June 2011 and January 2012. Biopsies were collected from the Endoscopy Department in Duhok and Sulaimania hospitals, Kurdistan region, northern Iraq. PATIENTS AND METHODS: Upper gastrointestinal (GI) endoscopy examination was performed and 4 gastric biopsies (2 from the antrum and 2 from the corpus) were obtained from 204 patients. H pylori positivity was examined by CLO test; then the association between disease status and virulence factors was assessed by polymerase chain reaction. RESULTS: 154 (75%) of our samples were found to be H pylori + by CLO test. Endoscopic diagnoses for those who were positive were as follows: peptic ulcer disease (PUD) including duodenal ulcer, 45; gastric ulcer, 23; and no ulcer (NPUD), 86. The overall prevalence rates of cagA and dupA were 72.7% and 18.8%, respectively. While a significant association between cagA and PUD was observed (P. ≤.017; OR=0.4; CI=0.18­0.85), no relationship between dupA and PUD could be seen. CONCLUSION: These data suggested that the presence of cagA may be a predictor of clinical outcome in Kurdistan region, northern Iraq.

Infection with Helicobacter pylori strains carrying babA2 and cagA is associated with an increased risk of peptic ulcer disease development in Iraq.

BACKGROUND AND STUDY AIM: Several genes of Helicobacter pylori, such as vacA, cagA, iceA and babA, have been reported to significantly increase the risk of gastrointestinal diseases. The aim of this study was to study the relationship between H. pylori virulence factors and clinical outcomes and identify the independent markers of peptic ulcer disease in Iraq. PATIENTS AND METHODS: DNA was extracted from specimens taken from 154 unselected H. Pylori positive Iraqi patients. Genotyping was performed by the polymerase chain reaction (PCR), using specific primers for cagA, vacA (s, m), iceA and babA2 genes. RESULTS: A total of 56 (82%) peptic ulcer disease (PUD) patients carried cagA+ strains, significantly more than the 56 (65%) non-ulcer disease (NUD) patients (p=0.017). The difference in the prevalence of babA2 positivity was significant between patients with NUD (33.7%) and PUD (58.8%) (p=0.002). In addition, babA2 was associated as an independent factor, with PUD (p=0.005; odds ratio (OR)=0.4; confidence interval (CI)=0.18-0.68) followed by cagA (p=0.05; OR=0.4; CI=0.18-0.85). Forty-five isolates (29%) were typed as 'triple positive' strains, and their presence was significantly associated with PUD (p=0.001). CONCLUSION: The cagA and babA2 genotypes might be considered as useful markers for PUD patients. However, iceA1 and iceA2 seem not to be good markers for the disease. The presence of H. pylori strains with triple-positive status is of high clinical relevance to H. pylori-associated diseases.

Performance of a nurse-led paediatric point of care service for respiratory syncytial virus testing in secondary care.

OBJECTIVES: To evaluate respiratory syncytial virus (RSV)-point-of-care-testing (POCT) performance among paediatric patients with respiratory symptoms, using the BinaxNOW(®) RSV assay performed by trained nurses on the paediatric ward, and compare results with those obtained by real-time polymerase chain reaction (PCR). METHODS: Four paediatric nurses were trained and certified in using RSV-POCT. Between October 2008 and March 2009, all hospitalised children below 5 years of age presenting with a suspected RSV infection had nasopharyngeal swabs (NPS) tested by RSV-POCT by the nurses and a real-time PCR targeting common respiratory viruses by laboratory staff. RESULTS: Among 159 NPS, 21 (13.2%) were RSV-POCT positive and 138 (86.8%) negative. All 21 RSV-POCT positive samples were positive by PCR, yielding a specificity of 100% (95% CI 95.7%, 100.0%). Of 138 RSV-POCT negative samples, 30 (21.7%) were RSV positive by PCR (sensitivity 41.2%; 95% CI: 27.9%, 55.8%). The positive and negative predictive values for RSV-POCT were 100% (95% CI 80.8%, 100.0%) and 78.3% (95% CI 70.3%, 84.6%) respectively. Other respiratory viruses were detected in 52/138 (39.9%) NPS. CONCLUSIONS: A POCT for RSV run by trained nurses can be used reliably as a first screening step in symptomatic children. Negative samples should be analysed for RSV and other respiratory pathogens by real-time PCR.

Are false negative direct immnufluorescence assays caused by varicella zoster virus gE mutant strains?

Strains of Varicella zoster virus (VZV) have been described recently in which a single base mutation in the gE epitope abrogates binding of the 3B3 monoclonal antibody, which is widely used for virus detection in diagnostic laboratories. These strains, named VZV-MSP, are associated with a distinct phenotype in both in vitro culture and in SCID-hu mice. We investigated the possibility that negative direct immunofluorescence results, using the 3B3 antibody, where the presence of virus was confirmed by polymerase chain reaction (PCR) or tissue culture are due in some cases to the MSP strain of VZV. A total of 249 vesicle fluid specimens from people with suspected shingles were examined using direct immunofluorescence, tissue culture and a nested multiplex PCR for VZV, herpes simplex virus type 1 (HSV-1) and 2 (HSV-2). VZV was detected in 218 of 249 (87.6%) cases. Forty-five confirmed VZV specimens, but with negative (30) or indeterminate (15) immunofluorescence results, were analysed further. PCR was used to amplify a fragment in ORF 68 that encodes the VZV gE ectodmain recognised by 3B3 antibody. The fragments were sequenced and analysed for the single base change G448A (D150N), which is present in VZV-MSP as compared with the reference Dumas strain. No VZV gE mutant (MSP/MSP-like) was detected. Overall, PCR was found to be the most sensitive method of confirming VZV infection. False negative VZV immunofluorescence results are unlikely to be due to virus variants.

A study of shingles and the development of postherpetic neuralgia in East London.

The incidence of post-herpetic neuralgia following shingles and the factors that are known to predict it were examined in a prospective observational community study of patients with acute shingles presenting to their family doctors. The detection of viral DNA in the blood at presentation as a prognostic indicator for pain was also evaluated. Patients were followed for one year and the persistence of pain following rash assessed. Among 165 patients who had completed 6 months, and 139 one-year follow-up, the prevalence of post herpetic neuralgia was 30% at 6 weeks 27% at 12 weeks, 15.9% at 6 months, and 9% at one year. Age and severity of pain were significantly associated with the persistence of pain beyond 3 months. Viremia at presentation was detected in 66% of patients and was significantly associated with the presence of pain at six months or beyond. Antiviral agents were administered to only 50% of those at highest risk of post-herpetic neuralgia (PHN) mainly because of presentation longer than 72 hours after the onset of rash. Few patients were prescribed the more potent prodrugs, Valaciclovir and Famciclovir. In conclusion, treatment of acute shingles in this observational community-based study was suboptimal in 50% of cases. More accurate prediction of which subset of elderly patients are most at risk of PHN may enable targeted prescribing of the most potent drugs to those most likely to benefit.

The molecular epidemiology of varicella-zoster virus: evidence for geographic segregation.

Of 75 varicella-zoster virus (VZV) isolates obtained from patients in Africa, Asia, and the Far East, 74 (98.6%) were found to be positive for a BglI restriction site in gene 54. By contrast, <22% of strains from patients in the United Kingdom and in North and South America were positive for the BglI restriction site. Viruses positive for BglI were significantly more common in zoster occurring in patients of nonwhite origin (P<.05). Irrespective of the country in which the sample was obtained, 98% of strains positive for BglI clustered within a single phylogenetic group, which we termed "group A"; the exception was 1 strain that appeared to be recombinant genotype C/A. We used the BglI site to examine both the spread of type A viruses in the United Kingdom and the patterns of VZV infections within persons from different ethnic groups who grew up in the United Kingdom or abroad.