Detection of new genotypes of Orientia tsutsugamushi infecting humans in Thailand.

PCR screening of blood specimens taken from 195 patients with serologically confirmed scrub typhus in three Thai provinces detected the 56-kDa protein-encoding gene from Orientia tsutsugamushi in ten (5%) patients. Significant genetic diversity was found among the ten amplicons, with nine new genotypes identified that were different from those found previously in Thailand. Phylogenetically, the ten sequences obtained in the present study and sequences from 71 strains characterised previously were distributed into several clusters that included the Karp, Gilliam, Kuroki, Saitama, Kawasaki and Kato clusters. Two of the new genotypes found in the present study clearly belonged to the Karp cluster. However, the other new genotypes formed three different clusters, including one cluster that appeared to be distant from all previously known clusters, and which may therefore be representative of a previously undescribed serotype. Other genotypes formed two other clusters that may also be associated with undescribed serotypes.

Scrub typhus: chest radiographic and clinical findings in 130 Thai patients.

OBJECTIVE: To describe chest radiographic findings and their clinical correlation in patients with scrub typhus diagnosed in Thailand and to determine abnormalities that assist in the diagnosis of scrub typhus. MATERIAL AND METHOD: Between July 2001 and December 2002, 130 patients with scrub typhus admitted to three hospitals in the northeastern Thailand were studied. Data of clinical presentations and chest radiographic findings, reviewed by two radiologists who were unaware of the final diagnosis, were analyzed. RESULTS: There were 33 women, 97 men; age range, 11-92 years; median age, 45 years old. Pulmonary symptoms occurred in 61.5% of the patients and eschar was found in 33.1%. Hepatic dysfunction occurred in 58.5% and cardiovascular dysfunction in 33%. Pulmonary involvement was the major presentation in 41.5%. Acute respiratory distress syndrome developed in 7 patients. Overall 5 patients died. The initial radiography showed abnormalities in 64.6% of the patients. Common radiographic abnormalities included bilateral reticular opacities (48.5%), cardiomegaly (28.5%), congestive heart failure (18.5%), air space nodules (13.1%), and pleural effusion (10.8%). Significant association between chest radiographic abnormalities and hepatic and cardiovascular dysfunction were documented. CONCLUSION: Chest radiography should be included in the initial evaluation of patients with suspected scrub typhus. Bilateral reticular infiltration, with or without cardiomegaly or congestive heart failure, was the most frequent radiographic finding of scrub typhus.

The epidemiology of melioidosis in Ubon Ratchatani, northeast Thailand.

BACKGROUND: Melioidosis, or infection with Pseudomonas pseudomallei is an important cause of morbidity and mortality in South East Asia and Northern Australia. The epidemiology of melioidosis in Ubon Ratchatani, Northeast Thailand was studied over a 5-year period from 1987 to 1991. METHODS: Rates and, when possible, the risks of developing melioidosis were calculated. The numerator was the number of culture-proven cases of melioidosis seen in the 1000-bed referral hospital of the province. The denominators were obtained from the population census, a survey of Health, Welfare and Use of Traditional Medicine, and the North Eastern Meterological Centre, Thailand. RESULTS: The average incidence of human melioidosis was 4.4 (95% confidence interval [CI]: 3.8-5.0) per 100,000. The disease affected all ages with the highest incidence in 40-60 years olds. Melioidosis was 1.4 (95% CI: 0.4-5.3) times more common in males than females. The disease showed a significant seasonal variation in incidence, and a strong linear correlation with rainfall (r = 0.7, 95% CI: 0.5-0.9) Adults exposed to soil and water in their work (most were rice farmers) had an increased risk of melioidosis (in the 40-59 year age group, relative risk = 4.1, 95% CI: 2.4-6.9). Most adult patients had an underlying disease (mainly diabetes mellitus) predisposing them to this infection. CONCLUSION: Melioidosis may result from either acute exposure to the organism in the soil and water, or 're-activation' of an asymptomatic childhood infection (by an unidentified possibly infective seasonal cofactor). The results from this analysis are consistent with both hypotheses. Further epidemiological studies are needed to identify risk factors so that optimal strategies for control of melioidosis may be developed.

Immunofluorescence microscopy for the rapid diagnosis of melioidosis.

A direct immunofluorescent antibody test (DIF) was developed for the rapid diagnosis of melioidosis, a potentially fatal infection caused by Pseudomonas pseudomallei. In a clinical evaluation of 369 sputum, pus, or urine specimens from 272 patients with suspected melioidosis, the DIF had a sensitivity of 73% and a specificity of 99% compared with culture. Using this DIF, a confident diagnosis of melioidosis can now be made within two hours of admission to hospital, compared with the delay of two to four days required for culture results. Consequent early institution of specific antimicrobial therapy may help to save lives.

Latex agglutination for rapid detection of Pseudomonas pseudomallei antigen in urine of patients with melioidosis.

A latex agglutination test for the detection of Pseudomonas pseudomallei antigen in urine was evaluated for the rapid diagnosis of melioidosis. With unconcentrated urine, antigen was detected in only 18% of patients with melioidosis overall. However, when urine was concentrated 100-fold, antigen was detected in 47% overall and in 67% of patients with septicaemia or disseminated infection, in whom a rapid diagnosis is most important. The specificity of the test was 100%. These results compared favourably with an enzyme immunoassay. This latex agglutination test is a simple, rapid and highly specific method of diagnosing melioidosis, and will be particularly useful in areas with limited laboratory facilities.

Amoxycillin-clavulanic acid treatment of melioidosis.

Melioidosis is a serious infection with high acute mortality, and a high rate of relapse despite protracted antimicrobial treatment. The current recommended conventional oral treatment regimen is a 4-drug combination of high-dose chloramphenicol, doxycycline and trimethoprim-sulphamethoxazole given for between 6 weeks and 6 months. We have evaluated prospectively the use of amoxycillin-clavulanic acid, to which Pseudomonas pseudomallei is consistently sensitive in vitro, for the oral maintenance treatment of melioidosis. Amoxycillin-clavulanic acid was used either as sole treatment of localized disease, or as maintenance therapy following either parenteral ceftazidime or the conventional 4-drug regime; 20 patients with localized infections and 26 with septicaemic melioidosis received a median of 7.5 (2-12) weeks treatment. After a mean follow-up period of 6 months (range 1-19), 31 patients (67%) remain free of disease. The drug was well tolerated. Three patients had fatal relapses, one other died suddenly at home, and another died from underlying promyelocytic leukaemia. The remaining 10 relapses were treated successfully. Resistance developed in one case. Amoxycillin-clavulanic acid is a safe alternative to the conventional 4-drug antimicrobial combination for the oral treatment of melioidosis. It may be of particular value in children, pregnant women, and in infections with Ps. pseudomallei resistant to the potentially toxic conventional regimen, but the optimum dose and duration of therapy need to be established.

The use of bone marrow culture for the diagnosis of melioidosis.

We have evaluated prospectively the contribution of bone marrow culture to the diagnosis of melioidosis. Bone marrow (BMC) and blood cultures (BC) were collected concurrently from 105 patients with suspected acute, severe melioidosis. 67 patients were subsequently proved to have the disease whilst other significant organisms were isolated from these specimens in 5 cases. Overall, 67.2% of BC and 64.2% of BMC from melioidosis patients grew Pseudomonas pseudomallei. Time to positivity did not differ significantly in paired BC and BMC specimens. These results do not support the routine use of BMC in the diagnosis of acute, severe melioidosis. In one patient with pulmonary melioidosis, however, blood cultures were repeatedly negative, whilst bone marrow grew P. pseudomallei, and this preceded the development of a distant focus of infection. This suggests that culture of bone-marrow may be of value in certain blood culture-negative patients with melioidosis.

A prospective comparison of co-amoxiclav and the combination of chloramphenicol, doxycycline, and co-trimoxazole for the oral maintenance treatment of melioidosis.

An open randomized comparison of the oral 'conventional' regimen (combination of chloramphenicol, cotrimoxazole and doxycycline) and co-amoxiclav for the maintenance treatment of melioidosis was conducted in Ubon Ratchatani, north-eastern Thailand, between 1989 and 1992. The total antibiotic treatment duration was 20 weeks. Of 101 patients followed, 10 (10%; 95% confidence interval [CI] 4.9-17.5%) subsequently relapsed: 2 of 52 patients (4%) in the oral 'conventional' group, and 8 of 49 patients (16%) receiving oral co-amoxiclav. This compares with a relapse rate of 23% in our previous study of 8 weeks' total therapy. Only 50% of patients complied with the 20 weeks' treatment regimen and poor compliance proved the most significant risk factor for subsequent relapse (relative risk [RR] 4.9, 95% CI 1.2-20.3). Neither the presence of known underlying disease nor choice of initial parenteral treatment was significantly associated with a higher risk of relapse. Co-amoxiclav is safer and better tolerated, but may be less effective (RR of relapse 0.4, 95% CI 0.2-1.2) than the oral 'conventional' regimen. The minimum duration of total treatment with either regimen should be 12-20 weeks, depending on clinical progress.

Lack of a significant adverse cardiovascular effect of combined quinine and mefloquine therapy for uncomplicated malaria.

Quinine dihydrochloride (10 mg salt/kg infused over one hour) and mefloquine (15 mg base/kg) were given simultaneously to 13 adults with uncomplicated falciparum malaria. Supine and standing blood pressures were recorded and the electrocardiogram monitored. Plasma concentrations of the 2 drugs were similar to those reported previously for the 2 compounds given individually to a similar group of patients. Although postural hypotension was common (6 cases before treatment and 7 after) and the electrocardiogram QTc interval was prolonged by a mean of 12% (SD = 8) following drug treatment, there was no evidence of a clinically significant cardiovascular pharmacodynamic interaction between these 2 structurally related antimalarial compounds.

Glucose tolerance in rural diabetic Thais, first-degree relatives and non-diabetic controls.

To determine whether non-insulin-dependent diabetes mellitus (NIDDM) in a rural Thai population is characterised by insulin resistance and hyperinsulinaemia, 17 unselected diabetic outpatients from a regional hospital, five first-degree relatives and 10 healthy controls were studied. Subjects in these groups were matched as closely as possible for age and sex, and mean body mass indices were similar (mean +/- S.D.; 21.8 +/- 5.5, 20.6 +/- 1.4 and 21.8 +/- 2.3 kg/m2, respectively, P > 0.5). Beta-cell function (%B) and insulin sensitivity (%S), expressed relative to values for non-diabetic Caucasians, were assessed mathematically using the 'CIGMA' model and plasma glucose and insulin achieved after a standard 1-h glucose infusion. The diabetic patients had higher fasting plasma glucose concentrations than the controls (8.6 +/- 4.0 vs. 4.6 +/- 0.4 mmol/l, P < 0.01) but plasma insulin levels were comparable (geometric mean [-S.D.-+S.D.]; 4.0 [1.7-9.4] vs. 4.0 [1.7-9.2] mU/l, P > 0.1). %B in the diabetic group (21% [10-41]) was lower than in the controls (128% [88-187], P < 0.001) while %S tended to be higher (185% [86-400] vs. 111% [49-251], 0.1 > P > 0.05). Relatives had intermediate values of both variables. %S and %B correlated poorly in the diabetic group (P > 0.1) but together accounted for 90% of the variation in basal plasma glucose (multiple r = 0.95, n = 17, P < 0.0001). Beta-cell dysfunction appears the primary defect in diabetic patients from a Thai subsistence farming population. Insulin resistance may not always characterise NIDDM in geographical areas where a 'thrifty genotype' would be expected; other factors associated with diabetes in developing countries (such increased susceptibility to serious infections) may also influence diabetes prevalence.

Epidemiology of arabinose assimilation in burkholderia pseudomallei isolated from patients and soil in Thailand.

Burkholderia pseudomallei is an environmental saprophyte that has been isolated widely from soil in Southeast Asia and the relationship between environmental contamination and clinical melioidosis has been established. It has been shown that the arabinose assimilation property of B. pseudonrallei is probably one of the determinants indicating virulence of this organism. Therefore, the distribution of arabinose assimilation biotypes of B. pseudomallei collected from four geographic regions of Thailand was studied in order to determine an association between arabinose assimilation of B. pseudomallei and the uneven distribution of melioidosis found among these four areas. A total of 830 isolates of B. pseudomallei (412 patient isolates and 418 soil isolates) collected from the patients and soil in four regions of Thailand in 1997 were tested for an ability to grow on a minimal agar medium supplemented with L-arabinose. All patient isolates except one could not utilise arabinose (Ara-). For 418 soil isolates, 232 (55.5%) isolates were identified as Ara type. They comprised 180 (62.5%), 36 (46.8%), 6 (35.3%) and 10 (27.8%) isolates derived from northeastern, southern, northern and central regions respectively. The ratios of Ara- to Ara, were 1.7, 0.9. 0.5 and 0.4 among isolates collected from northeastern, southern, northern and central regions respectively. The prevalence of Ara- in soil isolates in northeast is significantly higher than those in other regions. This observation suggests that in addition to the presence of B. pseudomallei in soil which is one of the factors contributing to a burden of melioidosis in northeastern Thailand, the distribution of more virulent biotype (Ara-) soil isolates is a factor contributing to a high prevalence of melioidosis in northeastern Thailand as well.

Protozoan enteric infection in AIDS related diarrhea in Thailand.

The aim of this study was to determine the prevalence of enteric protozoa and other pathogens in AIDS patients with diarrhea in Bangkok, Thailand. Of 288 consecutive patients screened in the 10 month period between November 1999-August 2000 inclusive, 55 (19.2%) had Cryptosporidium spp, 13 (4.5%) had Isospora oocyst, 11 (3.8%) had Giardia lamblia, 3 (0.9%) had Entamoeba histolytica, and 1 (0.3%) had Iodamoeba butschlii infection. The prevalence of microsporidia was 11% in this study. Of 251 patients for whom stool culture for bacteria was performed, enteric bacterial pathogens isolated were Campylobacter spp in 18 (7.1%), Salmonella spp in 11 (4.3%), and Shigella spp in 1 (0.5%). Other pathogens found in these patients were Clostridium difficile in 16/102 (15.6%). Mycobacterium spp in 18/287 (6.2%), and Strongyloides stercoralis in 23/288 (8.0%). Overall, parasitic and bacterial pathogens were identified in 140 (48.6%) patients. These pathogens were identified by the routine simple wet smear technique in 32, formalin-ether concentration method in 46, culture for S. stercoralis in 5, and culture for bacteria in 30. Additional test, using modified Ziehl-Neelsen staining, identified cryptosporidial oocyst, isospora oocyst, and Mycobacterium spp in 72. The microsporidia, initially identified by modified trichrome blue staining, all were then determined to be Enterocytozoon bieneusi by thin sectioning electron microscopy. Protozoan and bacterial pathogens were confirmed to be important etiologic agents in diarrhea in AIDS in Thailand. They were all associated with increased mortality. Routine stool examination by simple wet smear detected only one-fourth of these pathogens. Therefore all diagnostic techniques for these organisms should be made more widely available in Thailand.

An open randomized controlled trial of desmopressin and pulse dexamethasone as adjunct therapy in patients with pulmonary involvement associated with severe leptospirosis.

Pulmonary involvement in leptospirosis is emerging as a common complication of severe leptospirosis. A prospective randomized controlled trial of desmopressin or high-dose (pulse) dexamethasone as adjunctive therapy in 68 patients with pulmonary involvement associated with severe leptospirosis was conducted between July 2003 and October 2006 at five hospitals in Thailand. There were 23 patients in the desmopressin group, 22 in the pulse dexamethasone group, and 23 in a control group who received standard critical care alone. The diagnosis of leptospirosis was confirmed in 52 patients (77%). There were 15 deaths (22%), of which eight patients received desmopressin, four patients received pulse dexamethasone, and three patients received critical care alone (p 0.19). Eight patients with confirmed leptospirosis died (five patients in the desmopressin group, one in the pulse dexamethasone group and two in the control group). The mortality was not significantly different in the desmopressin group or pulse dexamethasone group compared to the control group in both intention-to-treat patients, and in patients with confirmed leptospirosis. There were no serious events associated with desmopressin treatment, although pulse dexamethasone treatment was associated with a significant increase in nosocomial infection. The results of logistic regression analysis revealed that serum bilirubin level was the only significant risk factor associated with mortality (OR 0.759, 95% CI 0.598-0.965, p 0.024). The results obtained in the present study do not support the use of either pulse dexamethasone or desmopressin as adjunct therapy for pulmonary involvement associated with severe leptospirosis.

Epidemiology and clinical aspects of rickettsioses in Thailand.

Scrub typhus and murine typhus are widespread in Thailand. Clinical manifestations of both diseases are nonspecific and vary widely. Acute undifferentiated fever (AUF), with or without organ dysfunction, is a major clinical presentation of these two diseases. The epidemiology and clinical manifestations including severe complications of scrub typhus and murine typhus in Thailand are summarized. Sixteen hundred and sixty-three patients with AUF were studied in six hospitals in Thailand between 2000 and 2003. Scrub typhus and murine typhus were diagnosed in 16.1% and 1.7% of them, respectively. Clinical spectrum of murine typhus was similar to scrub typhus. Hepatic dysfunction and pulmonary involvement were common complications. Multi-organ dysfunction mimicking sepsis syndrome occurred in 11.9% of patients with scrub typhus. The mortality of severe scrub typhus varied from 2.6% to 16.7%. Awareness that scrub typhus and murine typhus are prominent causes of AUF in adults in Thailand improves the probability of an accurate clinical diagnosis. Early recognition and appropriate treatment reduces morbidity and mortality. Results from recent clinical studies from Thailand indicated that rational antimicrobial therapy would be doxycycline in mild cases and a combination of either cefotaxime or ceftriaxone and doxycycline in severe cases. Azithromycin could be considered as an alternative treatment when doxycycline allergy is suspected. This would be either curative, or have no ill effect, in the majority of instances. Failure to improve or defervesce within 48 hours would indicate the need to perform a thorough re-evaluation of clinical findings and initial laboratory investigation results, as well as a need to change antibiotic.

Causes of acute, undifferentiated, febrile illness in rural Thailand: results of a prospective observational study.

The adult patients who, between July 2001 and June 2002, presented at any of five hospitals in Thailand with acute febrile illness in the absence of an obvious focus of infection were prospectively investigated. Blood samples were taken from all of the patients and checked for aerobic bacteria and leptospires by culture. In addition, at least two samples of serum were collected at different times (on admission and 2-4 weeks post-discharge) from each patient and tested, in serological tests, for evidence of leptospirosis, rickettsioses, dengue and influenza. The 845 patients investigated, of whom 661 were male, had a median age of 38 years and a median duration of fever, on presentation, of 3.5 days. Most (76.5%) were agricultural workers and most (68.3%) had the cause of their fever identified, as leptospirosis (36.9%), scrub typhus (19.9%), dengue infection or influenza (10.7%), murine typhus (2.8%), Rickettsia helvetica infection (1.3%), Q fever (1%), or other bacterial infection (1.2%). The serological results indicated that 103 (12.2%) and nine (1%) of the patients may have had double and triple infections, respectively. Leptospirosis and rickettsioses, especially scrub typhus, were thus found to be major causes of acute, undifferentiated fever in Thai agricultural workers.