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Clinical Factors for Severity of Plasmodium falciparum Malaria in Hospitalized Adults in Thailand
Patrick Sagaki, Vipa Thanachartwet, Varunee Desakorn, Duangjai Sahassananda, Supat Chamnanchanunt, Wirongrong Chierakul, Punnee Pitisuttithum, Prajej Ruangkanchanasetr
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0071503
Abstract: Plasmodium falciparum is a major cause of severe malaria in Southeast Asia, however, there is limited information regarding clinical factors associated with the severity of falciparum malaria from this region. We performed a retrospective case-control study to compare clinical factors and outcomes between patients with severe and non-severe malaria, and to identify clinical factors associated with the requirement for intensive care unit (ICU) admission of patients with severe falciparum malaria among hospitalized adults in Southeast Asia. A total of 255 patients with falciparum malaria in the Hospital for Tropical Diseases in Bangkok, Thailand between 2006 and 2012 were included. We identified 104 patients with severe malaria (cases) and 151 patients with non-severe malaria (controls). Patients with falciparum malaria with following clinical and laboratory characteristics on admission (1) referrals, (2) no prior history of malaria, (3) body temperature of >38.5°C, (4) white blood cell counts >10×109/μL, (5) presence of schizonts in peripheral blood smears, and (6) albumin concentrations of <3.5 g/dL, were more likely to develop severe malaria (P<0.05). Among patients with severe malaria, patients who met ≥3 of the 2010 WHO criteria had sensitivity of 79.2% and specificity of 81.8% for requiring ICU admission. Multivariate analysis identified the following as independent associated factors for severe malaria requiring ICU admission; (1) ethnicity of Thai [odds ratio (OR) = 3.601, 95% confidence interval (CI) = 1.011–12.822] or Myanmar [OR = 3.610, 95% CI = 1.138–11.445]; (2) referrals [OR = 3.571, 95% CI = 1.306–9.762]; (3) no prior history of malaria [OR = 5.887, 95% CI = 1.354–25.594]; and (4) albumin concentrations of <3.5 g/dL [OR = 7.200, 95% CI = 1.802–28.759]. Our findings are important for the clinical management of patients with malaria because it can help early identification of patients that could develop severe malaria and require ICU admission. Early identification and the timely initiation of appropriate treatments may well improve the outcomes and reduce the mortality of these patients.
Molecular detection and speciation of pathogenic Leptospira spp. in blood from patients with culture-negative leptospirosis
Siriphan Boonsilp, Janjira Thaipadungpanit, Premjit Amornchai, Vanaporn Wuthiekanun, Wirongrong Chierakul, Direk Limmathurotsakul, Nicholas P Day, Sharon J Peacock
BMC Infectious Diseases , 2011, DOI: 10.1186/1471-2334-11-338
Abstract: We evaluated our hypothesis during a prospective study of 418 consecutive patients presenting to a hospital in northeast Thailand with an acute febrile illness. Admission blood samples were taken for Leptospira culture and PCR. A single tube nested PCR that amplified a region of the rrs gene was developed and applied, amplicons sequenced and a phylogenetic tree reconstructed.39/418 (9%) patients were culture-positive for Leptospira spp., and 81/418 (19%) patients were culture-negative but rrs PCR-positive. The species associated with culture-positive leptospirosis (37 L. interrogans and 2 L. borgpetersenii) were comparable to those associated with culture-negative, PCR-positive leptospirosis (76 L. interrogans, 4 L. borgpetersenii, 1 unidentified, possibly new species).Molecular speciation failed to identify a unique bacterial subset in patients with culture-negative, PCR-positive leptospirosis. The rate of false-negative culture was high, and we speculate that antibiotic pre-treatment is the most likely explanation for this.Leptospirosis is an acute febrile illness caused by pathogenic species belonging to the genus Leptospira [1,2]. This zoonotic disease has a worldwide distribution but is most common in tropical and subtropical regions and has the greatest impact on public health in developing countries [1-4]. Disease is maintained by chronic carrier hosts that excrete the organism into the environment, and infection in man results from direct contact with infected animals or indirect contact with a contaminated environment [1-3].Leptospira are present in the blood during the first week of infective symptoms [1,2]. Culture is rarely performed in routine clinical practice since this may take several months and requires considerable expertise, which places it within the domain of specialist reference centres. Culture continues to have an important role, however, in defining the global epidemiology of infection [4]. Identification of the serovar of infecting isolate
Diagnostic Accuracy of Real-Time PCR Assays Targeting 16S rRNA and lipl32 Genes for Human Leptospirosis in Thailand: A Case-Control Study
Janjira Thaipadunpanit,Wirongrong Chierakul,Vanaporn Wuthiekanun,Direk Limmathurotsakul,Premjit Amornchai,Siriphan Boonslip,Lee D. Smythe,Roongrueng Limpaiboon,Alex R. Hoffmaster,Nicholas P. J. Day,Sharon J. Peacock
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0016236
Abstract: Rapid PCR-based tests for the diagnosis of leptospirosis can provide information that contributes towards early patient management, but these have not been adopted in Thailand. Here, we compare the diagnostic sensitivity and specificity of two real-time PCR assays targeting rrs or lipL32 for the diagnosis of leptospirosis in northeast Thailand.
Diagnostic Accuracy of a Loop-Mediated Isothermal PCR Assay for Detection of Orientia tsutsugamushi during Acute Scrub Typhus Infection
Daniel H. Paris ,Stuart D. Blacksell,Pruksa Nawtaisong,Kemajittra Jenjaroen,Achara Teeraratkul,Wirongrong Chierakul,Vanaporn Wuthiekanun,Pacharee Kantipong,Nicholas P. J. Day
PLOS Neglected Tropical Diseases , 2011, DOI: 10.1371/journal.pntd.0001307
Abstract: Background There is an urgent need to develop rapid and accurate point-of-care (POC) technologies for acute scrub typhus diagnosis in low-resource, primary health care settings to guide clinical therapy. Methodology/Principal Findings In this study we present the clinical evaluation of loop-mediated isothermal PCR assay (LAMP) in the context of a prospective fever study, including 161 patients from scrub typhus-endemic Chiang Rai, northern Thailand. A robust reference comparator set comprising following ‘scrub typhus infection criteria’ (STIC) was used: a) positive cell culture isolate and/or b) an admission IgM titer ≥1:12,800 using the ‘gold standard’ indirect immunofluorescence assay (IFA) and/or c) a 4-fold rising IFA IgM titer and/or d) a positive result in at least two out of three PCR assays. Compared to the STIC criteria, all PCR assays (including LAMP) demonstrated high specificity ranging from 96–99%, with sensitivities varying from 40% to 56%, similar to the antibody based rapid test, which had a sensitivity of 47% and a specificity of 95%. Conclusions/Significance The diagnostic accuracy of the LAMP assay was similar to realtime and nested conventional PCR assays, but superior to the antibody-based rapid test in the early disease course. The combination of DNA- and antibody-based detection methods increased sensitivity with minimal reduction of specificity, and expanded the timeframe of adequate diagnostic coverage throughout the acute phase of scrub typhus.
High Rates of Homologous Recombination in the Mite Endosymbiont and Opportunistic Human Pathogen Orientia tsutsugamushi
Piengchan Sonthayanon ,Sharon J. Peacock,Wirongrong Chierakul,Vanaporn Wuthiekanun,Stuart D. Blacksell,Mathew T. G. Holden,Stephen D. Bentley,Edward J. Feil,Nicholas P. J. Day
PLOS Neglected Tropical Diseases , 2010, DOI: 10.1371/journal.pntd.0000752
Abstract: Orientia tsutsugamushi is an intracellular α-proteobacterium which resides in trombiculid mites, and is the causative agent of scrub typhus in East Asia. The genome sequence of this species has revealed an unprecedented number of repeat sequences, most notably of the genes encoding the conjugative properties of a type IV secretion system (T4SS). Although this observation is consistent with frequent intragenomic recombination, the extent of homologous recombination (gene conversion) in this species is unknown. To address this question, and to provide a protocol for the epidemiological surveillance of this important pathogen, we have developed a multilocus sequence typing (MLST) scheme based on 7 housekeeping genes (gpsA, mdh, nrdB, nuoF, ppdK, sucD, sucB). We applied this scheme to the two published genomes, and to DNA extracted from blood taken from 84 Thai scrub typhus patients, from 20 cultured Thai patient isolates, 1 Australian patient sample, and from 3 cultured type strains. These data demonstrated that the O. tsutsugamushi population was both highly diverse [Simpson's index (95% CI) = 0.95 (0.92–0.98)], and highly recombinogenic. These results are surprising given the intracellular life-style of this species, but are broadly consistent with results obtained for Wolbachia, which is an α-proteobacterial reproductive parasite of arthropods. We also compared the MLST data with ompA sequence data and noted low levels of consistency and much higher discrimination by MLST. Finally, twenty-five percent of patients in this study were simultaneously infected with multiple sequence types, suggesting multiple infection caused by either multiple mite bites, or multiple strains co-existing within individual mites.
Strategies for Diagnosis and Treatment of Suspected Leptospirosis: A Cost-Benefit Analysis
Yupin Suputtamongkol ,Wirichada Pongtavornpinyo,Yoel Lubell,Chuanpit Suttinont,Siriwan Hoontrakul,Kriangsak Phimda,Kitti Losuwanaluk,Duangjai Suwancharoen,Saowaluk Silpasakorn,Wirongrong Chierakul,Nick Day
PLOS Neglected Tropical Diseases , 2010, DOI: 10.1371/journal.pntd.0000610
Abstract: Background Symptoms and signs of leptospirosis are non-specific. Several diagnostic tests for leptospirosis are available and in some instances are being used prior to treatment of leptospirosis-suspected patients. There is therefore a need to evaluate the cost-effectiveness of the different treatment strategies in order to avoid misuse of scarce resources and ensure best possible health outcomes for patients. Methods The study population was adult patients, presented with uncomplicated acute febrile illness, without an obvious focus of infection or malaria or typical dengue infection. We compared the cost and effectiveness of 5 management strategies: 1) no patients tested or given antibiotic treatment; 2) all patients given empirical doxycycline treatment; patients given doxycycline when a patient is tested positive for leptospirosis using: 3) lateral flow; 4) MCAT; 5) latex test. The framework used is a cost-benefit analysis, accounting for all direct medical costs in diagnosing and treating patients suspected of leptospirosis. Outcomes are measured in length of fever after treatment which is then converted to productivity losses to capture the full economic costs. Findings Empirical doxycycline treatment was the most efficient strategy, being both the least costly alternative and the one that resulted in the shortest duration of fever. The limited sensitivity of all three diagnostic tests implied that their use to guide treatment was not cost-effective. The most influential parameter driving these results was the cost of treating patients with complications for patients who did not receive adequate treatment as a result of incorrect diagnosis or a strategy of no-antibiotic-treatment. Conclusions Clinicians should continue treating suspected cases of leptospirosis on an empirical basis. This conclusion holds true as long as policy makers are not prioritizing the reduction of use of antibiotics, in which case the use of the latex test would be the most efficient strategy.
Feasibility of Modified Surviving Sepsis Campaign Guidelines in a Resource-Restricted Setting Based on a Cohort Study of Severe S. Aureus Sepsis
Weera Mahavanakul, Emma K. Nickerson, Pramot Srisomang, Prapit Teparrukkul, Pichet Lorvinitnun, Mingkwan Wongyingsinn, Wirongrong Chierakul, Maliwan Hongsuwan, T. Eoin West, Nicholas P. Day, Direk Limmathurotsakul, Sharon J. Peacock
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0029858
Abstract: Background The Surviving Sepsis Campaign (SSC) guidelines describe best practice for the management of severe sepsis and septic shock in developed countries, but most deaths from sepsis occur where healthcare is not sufficiently resourced to implement them. Our objective was to define the feasibility and basis for modified guidelines in a resource-restricted setting. Methods and Findings We undertook a detailed assessment of sepsis management in a prospective cohort of patients with severe sepsis caused by a single pathogen in a 1,100-bed hospital in lower-middle income Thailand. We compared their management with the SSC guidelines to identify care bundles based on existing capabilities or additional activities that could be undertaken at zero or low cost. We identified 72 patients with severe sepsis or septic shock associated with S. aureus bacteraemia, 38 (53%) of who died within 28 days. One third of patients were treated in intensive care units (ICUs). Numerous interventions described by the SSC guidelines fell within existing capabilities, but their implementation was highly variable. Care available to patients on general wards covered the fundamental principles of sepsis management, including non-invasive patient monitoring, antimicrobial administration and intravenous fluid resuscitation. We described two additive care bundles, one for general wards and the second for ICUs, that if consistently performed would be predicted to improve outcome from severe sepsis. Conclusion It is feasible to implement modified sepsis guidelines that are scaled to resource availability, and that could save lives prior to the publication of international guidelines for developing countries.
Burkholderia pseudomallei genome plasticity associated with genomic island variation
Sarinna Tumapa, Matthew TG Holden, Mongkol Vesaratchavest, Vanaporn Wuthiekanun, Direk Limmathurotsakul, Wirongrong Chierakul, Edward J Feil, Bart J Currie, Nicholas PJ Day, William C Nierman, Sharon J Peacock
BMC Genomics , 2008, DOI: 10.1186/1471-2164-9-190
Abstract: Five islands from B. pseudomallei strain K96243 were chosen as representatives of different types of genomic islands present in this strain, and their presence investigated in other B. pseudomallei. In silico analysis of 10 B. pseudomallei genome sequences provided evidence for the variable presence of these regions, together with micro-evolutionary changes that generate GI diversity. The diversity of GIs in 186 isolates from NE Thailand (83 environmental and 103 clinical isolates) was investigated using multiplex PCR screening. The proportion of all isolates positive by PCR ranged from 12% for a prophage-like island (GI 9), to 76% for a metabolic island (GI 16). The presence of each of the five GIs did not differ between environmental and disease-associated isolates (p > 0.05 for all five islands). The cumulative number of GIs per isolate for the 186 isolates ranged from 0 to 5 (median 2, IQR 1 to 3). The distribution of cumulative GI number did not differ between environmental and disease-associated isolates (p = 0.27). The presence of GIs was defined for the three largest clones in this collection (each defined as a single sequence type, ST, by multilocus sequence typing); these were ST 70 (n = 15 isolates), ST 54 (n = 11), and ST 167 (n = 9). The rapid loss and/or acquisition of gene islands was observed within individual clones. Comparisons were drawn between isolates obtained from the environment and from patients with melioidosis in order to examine the role of genomic islands in virulence and clinical associations. There was no reproducible association between the individual or cumulative presence of five GIs and a range of clinical features in 103 patients with melioidosis.Horizontal gene transfer of mobile genetic elements can rapidly alter the gene repertoire of B. pseudomallei. This study confirms the utility of a range of approaches in defining the presence and significance of genomic variation in natural populations of B. pseudomallei.Burkholderia pseu
Common TLR1 Genetic Variation Is Not Associated with Death from Melioidosis, a Common Cause of Sepsis in Rural Thailand
Narisara Chantratita, Sarunporn Tandhavanant, Nicolle D. Myers, Wirongrong Chierakul, Vanaporn Wuthiekanun, Weera Mahavanakul, Direk Limmathurotsakul, Sharon J. Peacock, T. Eoin West
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0083285
Abstract: Melioidosis, infection caused by the Gram-negative bacterium Burkholderia pseudomallei, is a common cause of sepsis in northeast Thailand. In white North Americans, common functional genetic variation in TLR1 is associated with organ failure and death from sepsis. We hypothesized that TLR1 variants would be associated with outcomes in Thais with melioidosis. We collated the global frequencies of three TLR1 variants that are common in white North American populations: rs5743551 (-7202A/G), rs4833095 (742A/G), and rs5743618 (1804G/T). We noted a reversal of the minor allele from white North American subjects to Asian populations that was particularly pronounced for rs5743618. In the Utah residents of European ancestry, the frequency of the rs5743618 T allele was 17% whereas in Vietnamese subjects the frequency was >99%. We conducted a genetic association study in 427 patients with melioidosis to determine the association of TLR1 variation with organ failure or death. We genotyped rs5743551 and rs4833095. The variants were in high linkage disequilibrium but neither variant was associated with organ failure or in-hospital death. In 300 healthy Thai individuals we further tested the association of TLR1 variation with ex vivo blood responses to Pam3CSK4, a TLR1 agonist. Neither variant was robustly associated with blood cytokine responses induced by Pam3CSK4. We identified additional common variation in TLR1 by searching public databases and the published literature and screened three additional TLR1 variants for associations with Pam3CSK4-induced responses but found none. We conclude that the genetic architecture of TLR1 variation differs substantially in southeast Asians compared to other populations and common variation in TLR1 in Thais is not associated with outcome from melioidosis or with altered blood responses to Pam3CSK4. Our findings highlight the need for additional studies of TLR1 and other innate immune genetic modulators of the inflammatory host response and determinants of sepsis in southeast Asian populations.
A Dominant Clone of Leptospira interrogans Associated with an Outbreak of Human Leptospirosis in Thailand
Janjira Thaipadungpanit,Vanaporn Wuthiekanun,Wirongrong Chierakul,Lee D. Smythe,Wimol Petkanchanapong,Roongrueng Limpaiboon,Apichat Apiwatanaporn,Andrew T. Slack,Yupin Suputtamongkol,Nicholas J. White,Edward J. Feil,Nicholas P. J. Day,Sharon J. Peacock
PLOS Neglected Tropical Diseases , 2007, DOI: 10.1371/journal.pntd.0000056
Abstract: Background A sustained outbreak of leptospirosis occurred in northeast Thailand between 1999 and 2003, the basis for which was unknown. Methods and Findings A prospective study was conducted between 2000 and 2005 to identify patients with leptospirosis presenting to Udon Thani Hospital in northeast Thailand, and to isolate the causative organisms from blood. A multilocus sequence typing scheme was developed to genotype these pathogenic Leptospira. Additional typing was performed for Leptospira isolated from human cases in other Thai provinces over the same period, and from rodents captured in the northeast during 2004. Sequence types (STs) were compared with those of Leptospira drawn from a reference collection. Twelve STs were identified among 101 isolates from patients in Udon Thani. One of these (ST34) accounted for 77 (76%) of isolates. ST34 was Leptospira interrogans, serovar Autumnalis. 86% of human Leptospira isolates from Udon Thani corresponded to ST34 in 2000/2001, but this figure fell to 56% by 2005 as the outbreak waned (p = 0.01). ST34 represented 17/24 (71%) of human isolates from other Thai provinces, and 7/8 (88%) rodent isolates. By contrast, 59 STs were found among 76 reference strains, indicating a much more diverse population genetic structure; ST34 was not identified in this collection. Conclusions Development of an MLST scheme for Leptospira interrogans revealed that a single ecologically successful pathogenic clone of L. interrogans predominated in the rodent population, and was associated with a sustained outbreak of human leptospirosis in Thailand.
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