Melioidosis in the Philippines

Phenotypic and genetic alterations of Burkholderia pseudomallei in patients during relapse and persistent infections

The bacterium Burkholderia pseudomallei is the causative agent of melioidosis, a severe tropical disease associated with high mortality and relapse and persistent infections. Treatment of melioidosis requires prolonged antibiotic therapy; however, little is known about relapse and persistent infections, particularly the phenotypic and genetic alterations of B. pseudomallei in patients. In this study, we performed pulsed-field gel electrophoresis (PFGE) to compare the bacterial genotype between the initial isolate and the subsequent isolate from each of 23 suspected recurrent and persistent melioidosis patients in Northeast Thailand. We used whole-genome sequencing (WGS) to investigate multilocus sequence types and genetic alterations of within-host strain pairs. We also investigated the bacterial phenotypes associated with relapse and persistent infections, including multinucleated giant cell (MNGC) formation efficiency and intracellular multiplication. We first identified 13 (1.2%) relapse, 7 (0.7%) persistent, and 3 (0.3%) reinfection patients from 1,046 survivors. Each of the 20 within-host strain pairs from patients with relapse and persistent infections shared the same genotype, suggesting that the subsequent isolates arise from the infecting isolate. Logistic regression analysis of clinical data revealed regimen and duration of oral antibiotic therapies as risk factors associated with relapse and persistent infections. WGS analysis demonstrated 17 within-host genetic alteration events in 6 of 20 paired isolates, including a relatively large deletion and 16 single-nucleotide polymorphism (stocktickerSNP) mutations distributed across 12 genes. In 1 of 20 paired isolates, we observed significantly increased cell-to-cell fusion and intracellular replication in the second isolate compared with the initial isolate from a patient with persistent infection. WGS analysis suggested that a non-synonymous mutation in the tssB-5 gene, which encoded an essential component of the type VI secretion system, may be associated with the increased intracellular replication and MNGC formation efficiency of the second isolate of the patient. This information provides insights into genetic and phenotypic alterations in B. pseudomallei in human melioidosis, which may represent a bacterial strategy for persistent and relapse infections.

Pulmonary tuberculosis and melioidosis coinfection in Brunei Darussalam: the importance of awareness and screening

Both tuberculosis (TB) and melioidosis are endemic to certain parts of the world, including Brunei Darussalam, with TB being more widespread. Despite this, coinfection with TB and melioidosis is rarely encountered and reported. Although still uncommon, there has been an increase in the number of cases of this coinfection reported during the past 10 years, all of which have been in India and the World Health Organization's Western Pacific Region. We report a case of coinfection with pulmonary TB and melioidosis in a patient with poorly controlled diabetes mellitus. This 64-year-old man presented with symptoms and radiological features of pulmonary TB, confirmed by sputum smear, but sputum culture also yielded Burkholderia pseudomallei, the pathogen that causes melioidosis. Coinfection was detected due to our practice of routinely screening for other infections in patients suspected or confirmed to have pulmonary TB. This highlights the importance of awareness of melioidosis and the need to consider screening for infection, especially in endemic regions.

Disseminated Melioidosis presenting as pneumonia, femoral and sacral osteomyelitis, splenic abscess and high rectal fistula: A case report and review of literature

INTRODUCTION

Melioidosis is a rare infectious tropical disease caused by Burkholderia pseudomallei (B. pseudomallei), an environmental saprophyte usually habitating on soils of Southeast Asian fields. Most of the reported cases present with pneumonia and intra-abdominal abscess. Diagnosis is established by culture studies from the blood, sputum or abscess drainage. Management relies on culture-guided antibiotic treatment, with good prognosis. Surgical intervention is required in cases not responsive to medical management.

PRESENTATION OF CASE

We are presenting a case of Melioidosis in a 72 year old Filipino who presented with Pneumonia, Femoral and Sacral Osteomyelitis, Splenic Abscess and High Rectal Fistula. He was successfully managed with systemic antibiotic treatment and surgery. The splenic abscess was managed by splenectomy and a transverse loop colostomy was used for fecal diversion to address the rectal fistula.

DISCUSSION

Melioidosis varies in its presentation and thus management should be individualized, depending on the organs involved. Our patient presented with multiple foci of infection which rendered the treatment more complicated as compared to those reported previously in published literature. The pneumonia and the osteomyelitis were managed with aggressive systemic antibiotics but the other sites of infection required drainage and surgery.

CONCLUSION

Melioidosis is a rare infection caused by an environmental saprophyte Burkholderia pseudomallei. An accurate diagnosis using culture studies is essential to institute appropriate treatment. Antibiotic treatment complemented by surgery for specific organ involvement is essential for cure.