Burkholderia pseudomallei in soil samples from an oceanarium in Hong Kong detected using a sensitive PCR assay

Abstract

Melioidosis, caused by Burkholderia pseudomallei, is an emerging infectious disease with an expanding geographical distribution. Although assessment of the environmental load of B. pseudomallei is important for risk assessment in humans or animals in endemic areas, traditional methods of bacterial culture for isolation have low sensitivities and are labor-intensive. Using a specific polymerase chain reaction (PCR) assay targeting a Tat domain protein in comparison with a bacterial culture method, we examined the prevalence of B. pseudomallei in soil samples from an oceanarium in Hong Kong where captive marine mammals and birds have contracted melioidosis. Among 1420 soil samples collected from various sites in the oceanarium over a 15-month period, B. pseudomallei was detected in nine (0.6%) soil samples using bacterial culture, whereas it was detected in 96 (6.8%) soil samples using the specific PCR assay confirmed by sequencing. The PCR-positive samples were detected during various months, with higher detection rates observed during summer months. Positive PCR detection was significantly correlated with ambient temperature (P<0.0001) and relative humidity (P=0.011) but not with daily rainfall (P=0.241) or a recent typhoon (P=0.787). PCR-positive samples were obtained from all sampling locations, with the highest detection rate in the valley. Our results suggest that B. pseudomallei is prevalent and endemic in the oceanarium. The present PCR assay is more sensitive than the bacterial culture method, and it may be used to help better assess the transmission of melioidosis and to design infection control measures for captive animals in this unique and understudied environment.

Melioidosis mycotic aneurysm: An uncommon complication of an uncommon disease

“…Our patient was born in Hong Kong and had never resided in a village with rice paddy fields. It is likely that our patient was infected locally, given the increasing reports of melioidosis in our locality [1,4] as well his previous occupation as a water pipe worker. Although often presenting as community-acquired pneumonia and sepsis, melioidosis can involve almost any part of the body.…”

Metabolomic Profiling of Plasma from Melioidosis Patients Using UHPLC-QTOF MS Reveals Novel Biomarkers for Diagnosis

“…Although the disease is mainly endemic in Southeast Asia and Northern Australia, melioidosis has been increasingly reported in areas of the Asia-Pacific region, including India [ 1 , 2 ], Mauritius [ 3 ], South, Central and North America [ 4 , 5 , 6 ], and West and East Africa [ 7 , 8 ], which may suggest an expanding geographical distribution. B. pseudomallei is known to be a natural saprophyte, and therefore melioidosis is believed to be acquired through contact with contaminated soil and water in the environment [ 9 , 10 ]. Illness can be presented as an acute, subacute, or chronic process, with an incubation period of up to 26 years [ 11 ].…”

Metabolomic profiling of Burkholderia pseudomallei using UHPLC-ESI-Q-TOF-MS reveals specific biomarkers including 4-methyl-5-thiazoleethanol and unique thiamine degradation pathway

“…The exclusion of metabolites present in Gram-negative bacteria such as Enterobacteriaceae and other non-fermenters was important, since these bacteria are common causes of bacteremia. Moreover, differentiation of B. pseudomallei from B. thailandensis in clinical isolates may be important for accurate diagnosis of melioidosis, since B. thailandensis is much less virulent and was only rarely reported to cause invasive infections in humans [ 10 , 35 ]. Therefore, the identification of specific biomarkers for B. pseudomallei may help differentiate melioidosis from other Gram-negative bacterial infections.…”

“…Although melioidosis is mainly endemic in Southeast Asia and northern Australia, the disease has been increasingly reported in countries outside the Asia-Pacific region, such as India [ 1 , 2 ], Mauritius [ 3 ], South, Central and North America [ 4 – 6 ], and West and East Africa [ 7 , 8 ], suggesting an expanding geographical distribution. B. pseudomallei is a natural saprophyte and melioidosis is believed to be acquired through environmental contact with contaminated soil and water [ 9 , 10 ]. Illness can be presented as an acute, subacute, or chronic process, with an incubation period of up to 26 years [ 11 ].…”

“…The disease manifestations can range from subclinical infection, localized abscesses, pneumonia to fulminant sepsis, leading to a mortality rate of up to 19 % [ 12 ]. Besides human, melioidosis also affects a wide range of animals in endemic areas [ 10 , 13 ]. Treatment of melioidosis is often difficult, as B. pseudomallei is usually resistant to multiple antibiotics and prolonged antibiotics are required to prevent relapse [ 14 , 15 ].…”