Application of polymerase chain reaction to detect burkholderia pseudomallei and Brucella species in buffy coat from patients with febrile illness among rural and peri-urban population

Two Decades of Melioidosis in India: A Comprehensive Epidemiological Review

Melioidosis, caused by Burkholderia pseudomallei, is a potentially fatal infection, particularly affecting individuals with chronic conditions such as diabetes or kidney or liver diseases. This review examines melioidosis in India over the past two decades, focusing on its prevalence, risk factors and clinical manifestations. A PubMed search (2000-2024) identified a rise in melioidosis publications, with most from Southern India, followed by Eastern India, and an increase post-2019. Eight studies from 2010-2022 identified fever (86%), cough (26%) and joint pain (23%) as the most common symptoms, while diabetes (75%), alcohol abuse (19%) and cancer (6%) were primary predisposing factors. Severe clinical manifestations were also observed, including bacteremia (50%), pneumonia (37%) and splenic abscess (18%). Although environmental exposure risks were not significantly high, individuals with diabetes or chronic kidney disease, particularly those working in high-risk environments, were more likely to contract melioidosis. Cryptic environmental factors that might bridge known epidemiological risk factors are also addressed. The review emphasizes the increasing awareness and research in clinical epidemiology and also highlights a gap in studies on antimicrobial treatments, vaccines and environmental surveillance. Targeted interventions in diabetes and poverty hotspots could help control the disease more effectively.

A novel ready-to-use loop-mediated isothermal amplification (LAMP) method for detection of Burkholderia mallei and B. pseudomallei

BACKGROUND

Glanders and melioidosis are contagious zoonotic diseases caused by Burkholderia mallei and B. pseudomallei, respectively. Bacterial isolation and polymerase chain reaction (PCR) have been used to detect these bacteria in animals suspected of infection; however, both methods require skilled experimental techniques and expensive equipment. These obstacles make it difficult to diagnose B. mallei and B. pseudomallei infections in areas where reagents and equipment are difficult to procure. To solve this problem, we developed an easy and ready-to-use dried-format diagnostic tool based on loop-mediated isothermal amplification (LAMP) method.

RESULTS

The primer set targeting the internal transcribed spacer (ITS) region detected 10 genomic copies of B. mallei DNA and B. pseudomallei DNA using the conventional liquid LAMP method. This primer set did not detect any other Burkholderia species. Using this novel primer set, a dried-format in-house LAMP method with high sensitivity and specificity was developed. This method was used to test for the presence of B. mallei DNA in swabs collected from the nasal cavity and ulcerated skin of 19 B. mallei-infected horses and five uninfected horses and was compared with the real-time PCR method. These two tests showed 87.5% agreement for the positive samples and 100% agreement for the negative samples. This method detected all tested B. pseudomallei clinical isolates.

CONCLUSIONS

We established the first dry LAMP method for the detection of B. mallei and B. pseudomallei. This study provided a simple, rapid, cost-effective, and sensitive diagnostic tool for glanders and melioidosis.

Are we dealing with melioidosis under the mask of tuberculosis? - A case series

Melioidosis is prevalent in South-East Asia. India is now become endemic to melioidosis. Melioidosis mimicks Tuberculosis (TB) and is often overlooked clinically. The spectrum of disease ranges from acute pulmonary infection to focal infection and septicemia. We report three cases of melioidosis, which was primarily suspected to be tuberculosis due to similarities in the clinical features. All patients were male and had risk factors such as type 2 diabetes mellitus as well as other risk factors such as chronic obstructive pulmonary disease (COPD), systemic hypertension, glucocorticoid therapy etc. All three patient samples were culture negative as well as negative for tests performed for the detection of tuberculosis. Conventional nested PCR targeting 251bp of 16S-23S spacer region of B. pseudomallei. was performed among individuals suspected to have extrapulmonary Tuberculosis. The presence of 251 bp was considered positive for B. pseudomallei. All three patients were treated with third generation cephalosporin and recovered due to timely diagnosis. Patients suspected for tuberculosis should be screened for B. pseudomallei, especially when AFB smear and MTB GeneXpert are negative. Often clinical samples may be culture negative for B. pseudomallei as patients are treated with antibiotics, therefore it is worthwhile performing PCR for B. pseudomallei to rule in a diagnosis of melioidosis and initiate appropriate antibiotics.

Standardization of an in-house multiplex real-time polymerase chain reaction for the simultaneous detection of Toxoplasma gondii, Rubella virus, cytomegalovirus, herpes simplex Virus 1 and 2, and Treponema pallidum infection among pregnant women

Background

An in-house multiplex real-time polymerase chain reaction (PCR) was developed in two cocktails for the identification of six Toxoplasma gondii, Rubella virus, cytomegalovirus, herpes simplex virus (1 and 2), and Treponema pallidum (syphilis) (TORCH-S) agents, which causes congenital infection among pregnant women.

Objective

Standardization and validation of an in-house multiplex real-time PCR assay for the detection of TORCH-S infection.

Methods

This study was conducted from February 2017 to February 2019. Primers specific for T. gondii, Rubella virus, cytomegalovirus, herpes simplex virus (1 and 2), and T. pallidum were designed using Primer3 software (https://bioinfo.ut.ee/primer3-0.4.0/). The primer sequences obtained were subjected to BLAST analysis using BLAST database. Synthetic DNA was obtained to use as positive control templates for all the six TORCH-S agents. The lower limit of the detection was performed using plasmid construct for each virus serially diluted from 10^-1 to 10^-9.

Results

An in-house multiplex real-time PCR was standardized and validated in two cocktails for TORCH-S agents, cocktail-1 (HSV1, rubella, and T. gondii), and cocktail-2 (HSV2, CMV, and T. pallidum). The lower limit of the detection for HSV1, rubella, and Toxoplasma were 60.7 copies/10 μl input, 76.4 copies/10 μl input, and 34.4 copies/10 μl input and for HSV2, CMV, and T. pallidum were 80.8 copies/10 μl input, 166 copies/10 μl input, and 43.7 copies/10 μl input, respectively.

Conclusion

TORCH-S infection is one of the significant reasons for irregular pregnant outcomes. It is absolutely important to screen TORCH-S infection for women who had the histories of abnormal pregnancies to prevent birth defects and perinatal complications. This multiplex real-time PCR assay provides a rapid, sensitive, and specific technique to detect these six TORCH-S agents.

Diagnosis of melioidosis: the role of molecular techniques

Melioidosis is an emerging infectious disease with an estimated global burden of 4.64 million disability-adjusted life years per year. A major determinant related to poor disease outcomes is delay to diagnosis due to the fact that identification of the causative agent Burkholderia pseudomallei may be challenging. Over the last 25 years, advances in molecular diagnostic techniques have resulted in the potential for rapid and accurate organism detection and identification direct from clinical samples. While these methods are not yet routine in clinical practice, laboratory diagnosis of infectious diseases is transitioning to culture-independent techniques. This review article aims to evaluate molecular methods for melioidosis diagnosis direct from clinical samples and discuss current and future utility and limitations.

Antibodies in Melioidosis: The Role of the Indirect Hemagglutination Assay in Evaluating Patients and Exposed Populations

Melioidosis is a major neglected tropical disease with high mortality, caused by the Gram-negative bacterium Burkholderia pseudomallei (Bp). Microbiological culture remains the gold standard for diagnosis, but a simpler and more readily available test such as an antibody assay is highly desirable. In this study, we conducted a serological survey of blood donors (n = 1,060) and adult melioidosis patients (n = 200) in northeast Thailand to measure the antibody response to Bp using the indirect hemagglutination assay (IHA). We found that 38% of healthy adults (aged 17-59 years) have seropositivity (IHA titer ≥ 1:80). The seropositivity in healthy blood donors was associated with having a declared occupation of rice farmer and with residence in a nonurban area, but not with gender or age. In the melioidosis cohort, the seropositivity rate was higher in adult patients aged between 18 and 45 years (90%, 37/41) compared with those aged ≥ 45 years (68%, 108/159, P = 0.004). The seropositivity rate was significantly higher in people with diabetes (P = 0.008). Seropositivity was associated with decreased mortality on univariable analysis (P = 0.005), but not on multivariable analysis when adjusted for age, diabetes status, preexisting renal disease, and neutrophil count. This study confirms the presence of high background antibodies in an endemic region and demonstrates the limitations of using IHA during acute melioidosis in this population.

A multiplex nested PCR for the simultaneous detection of Salmonella typhi, Mycobacterium tuberculosis, and Burkholderia pseudomallei in patients with pyrexia of unknown origin (PUO) in Vellore, South India

BACKGROUND AND OBJECTIVES

Salmonella typhi, Mycobacterium tuberculosis, and Burkholderia pseudomallei are among the most important monocyte-tropic bacterial agents causing pyrexia of unknown origin (PUO), with a significant number of endemic infections in both South and Southeast Asian regions. These infections pose a major risk to travelers to these regions as well.

METHODS

We developed and evaluated a multiplex nested polymerase chain reaction (PCR) for the simultaneous detection of the three pathogens in 305 patients' buffy coat samples.

RESULTS

The assay for S. typhi and B. pseudomallei was able to detect down to 1 colony forming unit/5 μL PCR input and M. tuberculosis was detected down to 20 genome copies/5 μL PCR input. S. typhi was detected in 10 (3.3 %) individuals, B. pseudomallei in 10 individuals (3.3 %), and M. tuberculosis in 18 individuals (5.9 %). Co-infections of M. tuberculosis and B. pseudomallei were detected in three individuals and S. typhi and B. pseudomallei in two individuals.

CONCLUSION

This protocol is efficient for PUO diagnosis especially in Asian countries.