Transcript fgdfgdgsty - Latvijas universitāte

Combination of a microtiter plate method with the amplification
of the icaA/aap genes is an effective tool to determine biofilm formation in
Staphylococcus epidermidis isolates from Latvian patients
I. Liduma1,2, U. Bers1,2, A.Gorbatjuka1, A. Zilevica1, T. Tracevska1,2
1- Faculty of Medicine, University of Latvia, 2- Laboratory of Bioanalytical and Biodosimetry Methods, Faculty of Biology ,
University of Latvia
Objectives
Methods
Coagulase-negative staphylococci (CoNS) are major
nosocomial pathogens known by their ability to form
biofilm on the surfaces of foreign bodies introduced
(implanted) into the organism. The accumulative phase
of biofilm formation is linked to the production of
polysaccharide intercellular adhesin (PIA), which is
synthesized by icaADBC-encoded proteins and the
accumulation associated protein (AAP) encoded by
aap. In this study show the reliability of microtiter plate
method combined with the icaA/aap genes to determine
biofilm forming potential in patients from four Latvian
hospitals.
The study involved S.epidermidis cultures from clinical and
control groups isolated in 2009-2010. 81 cultures were
isolated from blood (n=45) and intravenous catheters (n=36)
in a case of laboratory confirmed bacteraemia from patients of
four hospitals in Riga, Latvia. Fifty-five S.epidermidis isolates
from normal nose epithelium flora were included in the control
group of 20-22 years old healthy volunteers. The fragments of
aap (399bp) and icaA (502bp) genes were detected by
amplification and visualised by gel electrophoresis. Biofilm
formation using microtitre plate was carried out as described
by Christensen et al. Methicillin resistance was determined by
the amplification of the mecA gene 310-bp fragment.
.
Results
Biofilm formation in 35 (43,2%) of S.epidermidis
isolates of clinical group and 12 (21,8%) of control
group isolates were detected
.
Results
on combination of microtiter plate method with
amplification of the ica/aap genes are shown in
Figure 1. The statistical analysis by Chi-square test
showed that results were statistically significant for
. BF+/aap+/icaA+ (p=0.03) and BF−/aap−/icaA−
(p=0.009). Amplification of mecA gene determined
methicillin resistance in 79 (97.5%) of clinical group
and in 3 (5.4%) of control group samples .
.
.
Fig. 1. Frequency of biofilm forming clinical and
non clinical S.epidermidis strains in the
presence or absence of icaA and aap genes.
Conclusions
Our data indicates that the microtiter plate method only in combination with icaA/aap genes amplification is a realiable tool
for predicting invasiveness of S.epidermidis strains.
Methicillin resistance in nosocomial S.epidermidis strains is growing in Latvia (97.5% compared to 60-80% in 2004) and
remains at low level among healthy people, however, this tendence will be analysed in an additional, large scale study.
Project “Capacity building for interdisciplinary biosafety research”
No 2009/0224/1DP/1.1.1.2.0/09/ APIA/VIAA/055 coofunded by European Social
Fund