Multicentre evaluation of a new commercial latex agglutination test using a monoclonal antibody for rotavirus detection

[Evolution of the number of rotavirus and respiratory syncytial virus infections in children hospitalised in a French university hospital between 1998 and 2005]

AIM

Respiratory syncytial virus (RSV) and Rotavirus infections represent up to 30% of cross infections in pediatric units. As they are a major public health problem, we studied their evolution and distribution at the Dijon University Hospital.

POPULATION AND METHODS

This exhaustive retrospective study included children under 15 with a new Rotavirus or RSV infection who were hospitalised at the Dijon University Hospital between 1998 and 2005. The general trend was determined by using moving averages, and the Spearman correlation coefficient r(s) was calculated.

RESULTS

From 1998 to 2005, 1886 new RSV (n=981) or Rotavirus (n=905) infections were identified in hospitalised children. The number of the infections decreased significantly, both for RSV (r(s)=-0.71 ; p<0.0001) and for Rotavirus (r(s)=-0.77 ; p<0.0001). Almost half of Rotavirus infections were nosocomial (46.3%) vs 5.3% of RSV infections, p<0.0001. There was no significant difference in the proportion of RSV nosocomial infections between the epidemic and non-epidemic period (4.9% of nosocomial infections vs 7.1% respectively, p=0.25). Rotavirus nosocomial infections were less frequent in epidemic period (41.6%) than in non-epidemic period (54.6%); p=0.0002.

CONCLUSION

RSV and Rotavirus infections significantly decreased between 1998 and 2005. Proportion of RSV or Rotavirus infections didn't increase in epidemic period, which could be explained both by an increased attention from healthcare professionals and by the effectiveness of hygiene measures taken.

Évaluation de sept réactifs d'immunochromatographie pour détecter les rotavirus humains dans les selles

Seven commercially available immunochromatographic assays were tested for the rapid detection of group A rotaviruses in fecal samples compared to a enzyme immunoassay (Argene). Detection of rotaviruses in 80 ELISA positive frozen stool samples showed rates superior to 90% for three reagents (Rota Strip (Cypress Diagnostics), 98.8%; Rotascreen (Microgen), 95.0%; VIKIA Rota/Adeno (bioMérieux), 92.5%); from 82.5% to 88.8% for three others (Diarlex with centrifugation (Orion Diagnostica), 88.8%; Combo Rota/Adeno (All Diag), 87.5%; Rota/Adeno Combi Stick (bmd), 82.5%) and only 70.0% for Diarlex with filtration vial (Orion Diagnostica). The evaluation of the specificity, performed on one hundred fresh rotavirus negative stools, did not show any false positives with any assay. Analysis of the different technical features of these tests showed that they are quick and suitable for a clinical laboratory and do not require expensive equipment.

Effect of probiotic Lactobacillus strains in young children hospitalized with acute diarrhea

BACKGROUND

Oral bacteriotherapy promotes recovery from acute childhood diarrhea, but few strains have been shown to have therapeutic potentials. We examined the effect of two newly identified probiotic Lactobacillus strains in acute childhood diarrhea.

METHODS

Sixty-nine children were randomized during hospitalization for acute diarrhea to receive a mixture of Lactobacillus rhamnosus 19070-2 and Lactobacillus reuteri DSM 12246, 10(10) colony-forming units of each strain or placebo twice daily for 5 days. Before selection of these stains their potential probiotic characteristics were demonstrated in vitro and in healthy volunteers.

RESULTS

In patients receiving probiotics, the diarrheal phase was reduced by 20%. The duration of diarrhea was 82 h in the treatment group vs. 101 h in the control group (not significant, P = 0.07). However, 3 of 30 patients from the treatment group vs. 13 of 39 from the control group still had loose stools at the end of the study period (P = 0.03). In patients with diarrhea for <60 h before start of treatment (early intervention), a clear effect of the probiotics was demonstrated (80 h in the treatment group vs. 130 h in the control group, P = 0.003). After early intervention, the length of hospitalization was reduced by 48% (3.5 vs. 1.7 days, P = 0.03). At the end of the intervention, rotavirus antigen was found in 12% of patients from the treatment group vs. 46% from the control group (P = 0.02).

CONCLUSIONS

The two probiotics, L. rhamnosus 19070-2 and L. reuteri DSM 12246, ameliorated acute diarrhea in hospitalized children and reduced the period of rotavirus excretion. Oral bacteriotherapy was associated with a reduced length of hospital stay. The beneficial effects were most prominent in children treated early in the diarrheal phase.

[Nosocomial rotavirus infections in a general pediatric ward: epidemiology, molecular typing and risk factors]

OBJECTIVES

Nosocomial rotavirus infections induce difficult problems for pediatric wards during winter epidemics. This prospective study was carried out to measure their incidence in a general pediatric ward by using epidemiological tools, clinical and molecular methods, and to examine the main factors increasing the risk of cross contamination.

MATERIAL AND METHODS

The study was carried out on children, younger than three years old, hospitalized between 15 November 1996 and 1 March 1997. We examined the feces of all children for rotavirus on admission and during their hospital stay if they had developed diarrhea. The strains were typed by RNA electrophoresis. A cohort study was done to identify the factors of exposure to risk.

RESULTS

Three hundred twenty-six of the 415 hospitalized infants were studied. One hundred and five were hospitalized for gastroenteritis, including 39 (37.1%) with rotavirus infection. Among 221 infants admitted without diarrhea, 11 (5.0%) had an asymptomatic community infection and nine (4.3%) developed nosocomial gastroenteritis. The only significant predisposing factor (P = 0.003) for nosocomial infection was the distance between the hospital rooms and the nurses station. Despite the low level of typing (51%), the molecular study suggested a wide diversity of nosocomial and community strains.

CONCLUSION

The relatively low incidence of nosocomial infections found may be due to routine assignment to individual rooms, the isolation of infants admitted with acute diarrhea, and the policy of routine detection of asymptomatic carriers with the use of similar isolation measures for these children.

Rapid detection of rotavirus in faeces using a dipstick system with monoclonal antibodies and colloidal gold as marker

Rotavirus (RV) is known to be the most common cause of severe diarrhoea in infants and young children, each year leading to an estimated 800,000-900,000 deaths. RV also infects bovines and other species, with high morbidity and mortality. A rapid and simple 'naked-eye' dipstick system was developed to detect human RV in faeces, using nitrocellulose as solid phase, two monoclonal antibodies, and colloidal gold as marker. The system detects 10(4) viral particles (1-2 ng)/g of faeces. For human RV the specificity and sensitivity were 100% when compared with a commercial latex system, and 99% and 98%, respectively, when correlated with traditional RNA-PAGE, and 100% and 98% compared to an ELISA system.

Rotavirus infection in Tanzania: a virological, epidemiological and clinical study among young children

Rotavirus infection in the Dar es Salaam area of Tanzania was studied in 99 hospitalized children with acute diarrhoea and 99 hospitalized non-diarrhoea referents matched for sex and age. Of the diarrhoea cases 43.4% had rotavirus in the stools as opposed to 15.2% of the referents. The high carrier rate among the referents represents a serious risk of nosocomial transmission. More referents than cases had serum IgG antibodies to rotavirus, 52.5% and 35.4%, respectively (P < 0.02), while there was no correlation with serum IgM and IgA or faecal IgA antibodies. The latex agglutination test had a sensitivity comparable to that of electron microscopy (100%) and a specificity of 93.8%. The Slidex test appeared to be superior to the Rotalex test in that it gives very few false-positive reactions. The SDS-PAGE patterns of 11 RNA segments were compatible with the presence of group A strains with considerable heterogeneity among the strains. Symptoms and signs and some environmental data were recorded. None of them was clearly associated with rotavirus infection among the diarrhoea cases. It is concluded that rotavirus is a major cause of acute infectious diarrhoea in Tanzania.

[Acute diarrhea associated viruses : An update]

Viruses recovered in stools are either cultivable viruses (enteroviruses, adenoviruses excepted type 40 and 41), or "fastidious" non cultivable viruses (rotaviruses adenoviruses 40 and 41, Norwalk, calcivirus, astrovirus, SRSV and SRV). Non cultivable viruses have been associated with many cases of diarrhea. Norwalk, two strains of calicivirus and SRV/SRSV, appear to be capable of causing outbreak. Rotavirus, astrovirus and most fastidious adenoviruses are associated with endemic spread. Specific or catch-all methods are used for diagnosis. Among the latter, electron microscopy is the most commonly used when the virus is recognizable and present in sufficient quantities. Small spherical viruses in the range 20-35 nm present greater difficulties. Polyacrylamide gel electrophoresis gives interesting epidemiological results for rotavirus. Specific methods are latex agglutination and enzyme immunoassays essentially for rotavirus and adenoviruses (all types or only 40 and 41). False positive results are few with well-designed kits. False negative results are seen in atypical strains and antigenic variants. In an outbreak, it is essential to make electron microscopic examinations. In individual cases, if no electron microscope is available, it is possible to make the diagnosis of rotavirus - and perhaps adenovirus 40 and 41 with a commercial kit. However a small number of stools contain more than one virus and they may act in synergy. In contrast many asymptomatic children may carry viruses.