Current Diagnostic Approach
and
Role in Clinical Practice in Thailand
Direk Limmathurotsakul
Melioidosis Diagnostic Workshop
14th Sep 2013, Bangkok, Thailand
Thailand
76 provinces
- Each has one large
provincial hospital
(200 to 1,000 beds)
928 districts
- Each has one small
provincial hospital
(30 to 150 beds)
What policy makers saw
Melioidosis is a disease that needs to report to
Ministry of Public Health, Thailand, via Report 506
Melioidosis
Melioidosis Case Classification
(defined by MoPH, Thailand, 2001)
• Suspected case: None
• Probable case: Clinical criteria plus one IHA ≥ 1:160
• Confirmed case: Clinical criteria plus bacterial culture
positive for B. pseudomallei or IHA four-fold rising
Clinical criteria
• High fever with localized infection, septicaemia, or
septic shock without culture positive for other
pathogenic organisms
Official Data for Total Number of Melioidosis
in Thailand, Bureau of Epidemiology, MoPH
3,929
Number of cases and
of fatal cases (log scale)
10000
2,902
3,631
1,350
1000
360
402
421
651
920
1,098
100
10
6
7
8
8
11
15
10
14
5
Impossible!
How come?
2
1
03
04
05
06
07
08
09
10
11
12
Year (AD)
melioidosis case
fatal melioidosis case
www.boe.moph.go.th/boedb/surdata/506wk/y56/en/d72_3256_en.pdf
Conclusion 1 - IHA
• IHA is available in nearly every hospital in Thailand
• A lot of melioidosis cases in Thailand are (falsely)
diagnosed by IHA ≥ 1:160 or four-fold rise of IHA
• We found that standardization of IHA is problematic,
and some community hospitals gave a number of
false positive results
• Most doctors in Thailand believe that IHA is a good
diagnostic test without knowing its problem of poor
sensitivity and specificity
What researchers saw
B. pseudomallei is commonly isolated from clinical
specimens in NE, East, West and South Thailand
• In 2008, there were 2,557 culture-confirmed
melioidosis cases in NE Thailand 1
• There are regular report of melioidosis in South of
Thailand 2
• Between 2006-10, there were 8, 50, 76 and 151
culture-confirmed melioidosis in 4 provinces in West
and East Thailand 3
• In 1999, there was a report of 100 and 127 cultureconfirmed melioidosis patients in North and Central
Thailand 2
(1) Wongratanacheewin (IS-02), World Melioidosis Congress 2013
(2) Chusri et al. AJTMH (2012) 87(5): 927-32
(3) Limmathurotsakul et al. EID (2012) 18(2): 325-7
(4) Vuddhakul et al. AJTMH (1999) 60(3): 458-61
B. pseudomallei is commonly isolated from clinical
specimens in NE, East, West and South Thailand
• B. pseudomallei is the second most common cause of
community-acquired bacteremia in NE Thailand 2
• In short, researchers estimate that there are >2,500
culture-confirmed melioidosis cases per year
• Overall mortality of culture-confirmed melioidosis is
about 40% 1,2
(1) Limmathurotsakul et al. AJTMH (2010) 82(6): 1113-7
(2) Kanoksil et al. PLoS One (2013) 8(1) e54714
New Melioidosis Case Classification
(developed by researchers, and
proposed to MoPH, 2013)
• Suspected case: None
• Probable case: None
• Confirmed case: Any case with bacterial culture
positive for B. pseudomallei
• New study under collaboration between Faculty of
Tropical Medicine and Bureau of Epidemiology,
MoPH, Thailand is going to revise the official data of
melioidosis in Thailand using the routine culture
result of all microbiological laboratories in all
provincial hospitals in Thailand
Conclusion 2 - Culture
• Microbiology facilities are available in all 76
provincial hospitals in Thailand, university hospitals,
large private hospitals, and private commercial
laboratories
• Nonetheless, culture is not available in most
community hospitals (928 community hospitals)
• Identification of B. pseudomallei is still a problem
• We found that many microbiological laboratories do
not aware of B. pseudomallei and stop bacterial
identification at Pseudomonas spp.
• Some also discard B. pseudomallei as contamination
What researchers did
B. pseudomallei selective media
• Broth (Ashdown broth, TBSS-C50,..)
• Agar (Ashdown agar, BPSA, B.
cepacia medium, ..)
• Proved to be cost-effective, easy to
prepare, improve colony detection,
stop other flora in non-sterile
specimens
• Unfortunately, it is not formally
recommended by any government
documents or policies.
• Only available in few research
facilities (UBON and KK)
(1) Peacock et at JCM(2005) 43(10) 5350-5361
Latex Agglutination (LA)
• Based on Monoclonal Ab specific
to 200-kDa EPS B. pseudomallei 1
• Very useful, easy to use, and highly
sensitive and highly specific
• Recommended to be used for any
Gram-negative bacillus that is
oxidase +ve and not P. aeruginosa
• Unfortunately, it is neither
available for commercial use nor
from governmental agencies.
• Only available in few research
facilities (UBON and KK)
(1) Wuthiekanun et al AJTMH (2002) 66(6) 759-761
Immunofluorescent Assay (IFA)
• Based on Monoclonal Ab to EPS 1
• Moderately sensitive but highly
specific
• Use in clinical specimen directly
• Need IF microscopy. Less
sensitive than culture.
• Patients whom melioidosis is
suspected should be treated for
at least 4-7 days anyway (until
culture result is available)
• Available only in UBON
(1) Narisara et al AJTMH (2013) Epub ahead of print
Current Diagnostic Approach in Thailand
(In general, countrywide)
• Use clinical criteria (which is neither sensitive nor
specific)
• Start treatment if melioidosis is suspected by the
clinical criteria
• Order lab test for IHA
• Order blood culture with or without culture of other
clinical specimens
• No selective media for B. pseudomallei is used
• No latex agglutination is used
• Diagnose melioidosis based on clinical criteria, IHA or
culture
Recommended Diagnostic Approach in Thailand
(Used in Research Facilities / Settings [1])
• Use empirical treatment regimen to cover B.
pseudomallei (e.g. Cloxacillin + Ceftazidime) in areas
where melioidosis is present for all sepsis and severe
sepsis patients (unless definite diagnosis of other
diseases is made e.g. malaria, measles, ..)
• Ignore IHA
• Order blood, urine and throat swab culture
• Order pus and sputum culture if available
• Confirm laboratory that “selective media for B. ps”
and “latex agglutination” are used
• Order Ultrasound for abdomen (or CT scan if
possible)
Recommended Diagnostic Approach in Thailand
(Used in Research Facilities / Settings [2])
• Re-evaluate patients daily, search for abscesses and
collect more clinical specimens for culture if available
• Definite melioidosis = culture +ve
(report only this group to MoPH)
• Probable melioidosis = abscesses that is consistent with
melioidosis but culture was not done or negative, or
culture negative for B. ps and represent within 1 month
with culture-proven melioidosis
• Possible melioidosis = clinically suspected melioidosis
and improved after treatment with an effective
antimicrobial regimen for melioidosis or died before
improvement was observed
(1) Cheng et al AJTMH (2013) 88(3) 411-413
Conclusion
• There is a big gap between current and
recommended diagnostic approaches for melioidosis
in Thailand
• Simply lab tests and consumables such as B. ps
selective media and latex agglutination need to be
commercially available and supported by the
government policy
• New, rapid, simple, validated and accurate diagnostic
tests are still required, and a combination of antigen
and antibody detection is preferred
END