Melioidosis en Colombia, descripción de un caso clínico y consideraciones epidemiológicas / Melioidosis in Colombia, description of a clinical case and epidemiological considerations

Resumen La melioidosis es una enfermedad infecciosa causada por Burkholderia pseudomallei cuyo diagnóstico clínico puede ser difícil debido a su variada presentación clínica y a las dificultades del diagnóstico microbiológico, por lo cual pueden requerirse técnicas moleculares para su adecuada identificación una vez se sospecha su presencia. Son pocos los antibióticos disponibles para el tratamiento de esta enfermedad y, además, deben usarse durante un tiempo prolongado. Aunque se conoce por ser endémica en Tailandia, Malasia, Singapur, Vietnam y Australia, en Colombia se han reportado algunos pocos casos. Se presenta un caso de melioidosis en la región norte de Colombia, se hace una revisión de las características clínicas y el tratamiento, y se describe la epidemiología local de esta enfermedad.

Abstract Melioidosis is an infectious disease caused by Burkholderia pseudomallei whose clinical diagnosis can be difficult due not only to its varied clinical presentation but also to the difficulties in the microbiological diagnosis.Thus, it may be necessary to use molecular techniques for its proper identification once it is suspected. There are few antibiotics available for the treatment of this disease, which must be used over a long period of time. Although it is known to be endemic in Thailand, Malaysia, Singapore, Vietnam, and Australia, in Colombia there are few reported cases. We describe a case of melioidosis in the northern region of Colombia. Additionally, we review its clinical characteristics and treatment and we describe the local epidemiology of this disease.

The public health implications of melioidosis

Melioidosis, which is caused by the bacterium Burkholderia pseudomallei, is a potentially fatal tropical infection, little known outside its main endemic zone of Southeast Asia and northern Australia. Though it has received more attention in recent years on account of its claimed suitability as a biological weapon agent, the principal threat from melioidosis is a result of naturally occurring events. Occasional case clusters, sporadic cases outside the known endemic zone and infections in unusual demographic groups highlight a changing epidemiology. As melioidosis is the result of an environmental encounter and not person-to-person transmission, subtle changes in its epidemiology indicate a role environmental factors, such as man-made disturbances of soil and surface water. These have implications for travel, occupational and tropical medicine and in particular for risk assessment and prevention. Practical problems with definitive laboratory diagnosis, antibiotic treatment and the current lack of a vaccine underline the need for prevention through exposure avoidance and other environmental health measures. It is likely that the increasing population burden of the tropical zone and extraction of resources from the humid tropics will increase the prevalence of melioidosis. Climate change-driven extreme weather events will both increase the prevalence of infection and gradually extend its main endemic zone.

Emerging and re-emerging bacterial diseases in India.

There has been a remarkable progress in the prevention,control and even eradication of infectious diseases with improved hygiene and development of antimicrobials and vaccines. However,infectious diseases still remain a leading cause of global disease burden with high morbidity and mortality especially in the developing world. Furthermore, there have been threats of new diseases during the past three decades due to the evolution and adaptation of microbes and the re-emergence of old diseases due to the development of antimicrobial resistance and the capacity to spread to new geographic areas. The impact of the emerging and re-emerging diseases in India has been tremendous at socioeconomic and public health levels. Their control requires continuing surveillance,research and training,better diagnostic facilities and improved public health system. Emerging and reemerging zoonotic diseases, foodborne and waterborne diseases and diseases caused by multiresistant organisms constitute the major threats in India. This review of bacterial emerging and re-emerging diseases should be of critical importance to microbiologists,clinicians,public health personnel and policy makers in India.

Seroprevalence of Burkholderia pseudomallei in East Timorese refugees: implications for healthcare in East Timor.

Melioidosis is a disease with protean clinical manifestations caused by the bacterium Burkholderia pseudomallei. It is endemic in countries surrounding the newly independent East Timor, but has yet to be isolated or demonstrated serologically in that country. One illness that can be clinically indistinguishable from melioidosis is pulmonary tuberculosis, a condition with a very high prevalence in East Timor. We used an indirect hemagglutination test (IHA) to measure antibodies to B. pseudomallei in 407 East Timorese evacuated to Darwin, Australia, in September 1999. Assuming a positive IHA titer as > or = 1:40, the overall seroprevalence rate was 17.0%, in keeping with other seroprevalence studies from the region. The IHA titres ranged up to 1:320. After adjusting for age, females were 2.5 times more likely to be seropositive than males (p = 0.0001). There was an inverse relationship between seropositivity and age. This study shows that exposure to B. pseudomallei occurs in East Timor melioidosis is also likely to occur. Due to the lack of laboratory facilities at present, it may be some time before a laboratory-confirmed case proves that melioidosis occurs. In the meantime, clinicians in East Timor should include melioidosis in the differential diagnosis of the many conditions that it may mimic.

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.

Genotypic and phenotypic relationship in Burkholderia pseudomallei indicates colonization with closely related isolates.

Seven isolates of Burkholderia pseudomallei from cases of melioidosis in human (2 isolates) and animal (2 isolates), cat (one isolate) and from soil samples (2 isolates) were examined for in vitro sensitivity to 14 antimicrobial agents and for presence of plasmid DNA. Randomly amplified polymorphic DNA (RAPD) analysis was used to type the isolates, using two arbitrary primers. All isolates were sensitive to chloramphenicol, kanamycin, carbenicillin, rifampicin, enrofloxacin, tetracycline and sulfamethoxazole-trimethoprim. No plasmid was detected in all the isolates tested. RADP fingerprinting demonstrated genomic relationship between isolates, which provides an effective method to study the epidemiology of the isolates examined.

Indirect hemagglutination antibodies against Burkholderia pseudomallei in normal blood donors and suspected cases of melioidosis in Malaysia.

Interpretation of the indirect hemagglutination test (IHA) for melioidosis in endemic areas is difficult because of the presence of antibodies in apparently healthy individuals. Fifty-three out of 200 healthy blood donors in Malaysia showed positive antibody titers (> or = 1 : 40) against Burkholderia pseudomallei. Seven percent had an IHA titer of 1 : 40, 11% had an IHA titer of 1 : 80 while 8.5% had a titer > or = 1 : 160. Out of 258 sera sent for melioidosis serology, 7% of the patients had an IHA titer of 1 : 40, 9% had an IHA titer of 1 : 80 while 20% had an IHA titer of > or = 1 : 160. If a titer of > or = 1 : 80 is taken as cut off point for positivity, 29% of the patients had positive melioidosis serology. Increasing the positivity threshold may jeopardize the sensitivity of the test. A more specific and sensitive test is needed.

Emerging & re-emerging bacterial pathogens in India.

In spite of major successes against infectious diseases in the 20th century, new infectious diseases have emerged and old ones re-emerged in recent decades in different parts of the world. A brief survey of emerging and re-emerging bacterial diseases of public health importance in India is presented in this paper. Plague re-appeared in two outbreaks in Maharashtra and Gujarat in 1994, indicating a breakdown of the public health measures that had prevented its occurrence for several decades. Leptospirosis appears to be on the increase in Kerala, Tamilnadu and the Andamans during the last 2 decades, probably due to increased farming and inadequate rodent control. It is suggested that melioidosis due to the soil organism Burkholderia pseudomallei may be prevalent in many parts of India, but is under-diagnosed and under-reported. Since 1991, a completely new choleragenic Vibrio cholerae, designated 0139 has emerged in southern India and spread to other parts of India and to neighbouring countries, setting in motion the 8th cholera pandemic. Animal anthrax is very common in many parts of India, but human anthrax is recognised in only certain limited locations. In the Chittoor and North Arcot districts, its prevalence had increased in recent years. Since 1990, a multi-drug resistant variety of typhoid fever had been prevalent in many parts of India, caused by Salmonella typhi resistant to chloramphenicol, ampicillin and trimethoprim-sulphamethoxazole. Nosocomial methicillin-resistant Staphylococcus aureus infection seems to be widely prevalent in hospitals in many regions in India, and its prevalence seems to be on the rise. These pathogens pose new threats to public health, and call for appropriate responses. Microbiological expertise and epidemiological surveillance are deficient in the health care and public health systems in India; therefore even infections and diseases that have been under control elsewhere remain prevalent in the country, but are also under-diagnosed and under-reported. Without improving microbiological expertise and application as well as epidemiological skills and practices, emerging and re-emerging diseases may not be recognised, identified or intercepted in their early stages.

The 1990-1991 outbreak of melioidosis in the Northern Territory of Australia: epidemiology and environmental studies.

From November 1990 to June 1991 33 acute cases of melioidosis occurred in the Northern Territory, Australia; 25 cases were reported in the capital city, Darwin. We carried out an epidemiological investigation to exclude a common source outbreak, describe the risk factors for disease, and develop and institute appropriate control measures. We compared population based attack rates among various risk groups using logistic regression, and the demographic, medical and behavioral risk factors for melioidosis by a matched case-control study. Environmental Health Officers collected soil, surface water and cooling tower water specimens for Pseudomonas pseudomallei culture. The crude attack rate of melioidosis during the outbreak was 52 per 100,000. Age, gender, race, diabetes and alcohol abuse were independent risk factors for disease. The relative risk of disease in diabetic patients was 12.9 (95% CI 5.1-32.7; p < 0.001) and 6.7 in alcoholic patients (95% CI 2.9-15.2; p < 0.001). We found no significant difference between cases and controls in matched pair analysis for any of several exposure factors studied. We isolated Pseudomonas pseudomallei from 4% of soil samples and 9% of surface water samples. Our study confirms the importance of host factors in the development of melioidosis, and attempts to quantify the risk of disease during the Darwin epidemic. Pseudomonas pseudomallei is widespread in the soil of urban Darwin.

Acute systemic melioidosis: an autopsy study of six cases.

Autopsy findings of six cases of the acute systemic melioidosis from Siriraj Hospital, Bangkok, Thailand during the years 1977 to 1986 are presented. Five out of six cases had some underlying conditions. Multiple abscesses and multiple organs involvement were the rule. The organs most commonly involved were lung and liver. Three patients had pericardial and one had adrenal gland involvement. Other significant pathological findings were fibrin thrombi (5/6 cases), haemorrhage (6/6 cases), tissue necrosis (4/6 cases) and granular casts in renal tubules (1/6 case). Abscess alone cannot explain the death of patients. Toxaemia, both exotoxins and endotoxin, is the most likely explanation from the death of patients.