Biofilm formation by multidrug resistant Enterobacteriaceae strains isolated from solid organ transplant recipients

Solid organ transplant (SOT) recipients are especially at risk of developing infections by multidrug resistant bacteria (MDR). In this study, the biofilm-forming capability of 209 MDR strains (Escherichia coli n = 106, Klebsiella pneumoniae n = 78, and Enterobacter spp. n = 25) isolated from rectal swabs in the first 48 hours before or after kidney (93 patients), liver (60 patients) or kidney/pancreas transplants (5 patients) were evaluated by using a microplate assay. Thirty-nine strains were isolated before transplant and 170 strains were isolated post-transplant. Overall, 16% of E. coli strains, 73% of K. pneumoniae strains and 4% Enterobacter strains showed moderate or strong biofilm production. Nine strains isolated from infection sites after transplantation were responsible of infections in the first month. Of these, 4 K. pneumoniae, 1 E. coli and 1 Enterobacter spp. strains isolated pre-transplant or post-transplant as colonizers caused infections in the post-transplant period. Our results suggest that in vitro biofilm formation could be an important factor for adhesion to intestine and colonization in MDR K. pneumoniae strains in SOT recipients, but this factor appears to be less important for MDR E. coli and Enterobacter spp.

[Viral gastroenteritis. Application of a protocol for astrovirus detection in childhood gastroenteritis]

BACKGROUND AND OBJECTIVE

Diagnosis of viral gastroenteritis is an important subject in clinical virology which is mainly determined by the availability of reagents in laboratories, such as in the case of astrovirus. The aim of this study was to estimate the increase in the diagnostic performance achieved after the incorporation of astrovirus search in the diagnosis protocol of acute viral gastroenteritis. We also analyzed the trend of infections in other more commonly searched virus, such as rotavirus and enteric adenovirus.

MATERIAL AND METHODS

Retrospective study during 20 years that included 12,980 stool samples processed for gastroenteritis virus diagnosis. Since 1997 an enzyme immunoassay for astrovirus has been applied to those samples that are negative for rotavirus and adenovirus. The study was divided in two periods (1986-1996 and 1997-2005, without and with astrovirus diagnosis) and the percentage of patients diagnosed in each period was compared. The trend of positive results as well as the percentage of positive results over all patients studied was modelled using the least squares method.

RESULTS

The percentages of positive patients for rotavirus, adenovirus and astrovirus were 10.3%, 2.3% and 6.0% respectively, and there were uncommon co-infections by rotavirus and adenovirus (0.2%). The protocol applied to the astrovirus diagnosis increased the diagnosis rate up to 16.8% of the studied cases. Significant statistical differences were observed between the 2 study periods. A quadratic growth was observed in the results of positive diagnosis of viral gastroenteritis during the study period.

CONCLUSIONS

The search of astrovirus in gastroenteritis cases by a selective protocol increased the diagnostic performance of gastrointestinal virus by 6%. In view of these results, it would be useful to implement astrovirus diagnosis in faeces with liquid or semi-liquid consistency when rotavirus and adenovirus detection is negative.