Comparison of diffrent identifiation methods for B. pseudomallei in the diagnosis of Whitmore’s disease

Abstract

Burkholderia pseudomallei is a soil-dwelling bacterium
which can infect human and animals causing a fatal
infectious disease of melioidosis (or Whitmore’s disease).
The biological characteristics of this bacterium are
Gram-negative bacilli, oxydase-positive, naturally
resistant to gentamicin (Gen) and colistin (Col) but
sensitive to amoxicillin-clavulanic acid (AmC). To use
these particular characteristics for the identifiation of
B. pseudomallei, the authors investigated 169 oxydasepositive and Gram-negative bacilli strains isolated
from clinical specimens at Ha Tinh General Hospital
from July to December 2018. TTSS1 real-time PCR
assay, recA and 16S rRNA gene sequence analyses
confimed 17 strains as B. pseudomallei. These 17 strains
demonstrated the particular characteristics of threeantibiotic disc test with the diameter (r) Gen resistance
(r=6 mm), Col resistance (r=6 mm) and AmC sensitivity
(18 mm<r<26 mm). The identifiation accuracy of this
method for B. pseudomallei was 100% while the accuracy
of the two biochemistry methods API 20NE and Vitek 2
were 76.4% (13/17) and 29.4% (5/17), respectively. Five
strains of Cupriavidus malaysiensis were also resistant
to Gen and Col but sensitive to AmC with inhibition
zone diameter of 42-43 mm. In comparison with the
routine identifiation methods, the identifiation of B.
pseudomallei from oxydase-positive and Gram-negative
bacilli using three-antibiotic disc test was a reliable
and accurate method and could be implemented in the
medical microbiology laboratories in Vietnam to reduce
and avoid the misdiagnosis of melioidosis.