Identification of Burkholderia cepacia Complex: Comparing Conventional, Automated, and Molecular Methods in a Tertiary Care Center

Abstract

Introduction Burkholderia cepacia complex(BCC) is one of the most common polymyxin-resistant Gram-negative bacilli isolated in the clinical microbiological laboratory. They are often underreported when conventional biochemicals are used for identification, due to their similarity to other non-fermenting bacilli. It is essential to identify BCC using simple biochemical tests with good reliability to ease the identification of BCC in resource-limited settings and initiate treatment. Objectives We aim to identify isolates belonging to BCC from other non-fermenters using simple conventional biochemical tests, automated methods, and polymerase chain reaction (PCR) and analyze antibiotic profiles and treatment outcomes in patients with BCC infection. Materials and methods All samples received at the clinical microbiology laboratory for bacterial culture from March 2023 to March 2024 were included in this study. Samples that grew non-lactose fermenting colonies on MacConkey agar, which were resistant to polymyxin B 300 (PB300) units, were further identified using conventional biochemicals, and lysine decarboxylase test, ornithine decarboxylase test, arginine dihydrolase test, ortho-nitrophenyl-β-galactoside (ONPG) test, urea hydrolysis, triple disc screening test (polymyxin B 300 units, amoxicillin-clavulanic acid 20/10 mcg (AMC20/10), and gentamicin 10 mcg (GEN10)), VITEK MS (bioMérieux, Marcy-l'Etoile, France), VITEK 2 Gram-Negative (GN) Identification (ID) Card (bioMérieux), and PCR targeting groEL sequence was performed for Burkholderia isolates. The antibiotic susceptibility pattern was analyzed using VITEK AST (bioMérieux). Basic patient details were collected from the medical records. Results Using conventional biochemicals and automated methods, 60 isolates were identified belonging to the genus Burkholderia , among which 46 (76.6%) belonged to Burkholderia cepacia complex. The concordance for genus-level identification of Burkholderia with conventional biochemicals, VITEK MS, VITEK 2, and groEL PCR was found to be 100%. Species-level identification using the listed conventional biochemicals was 28.2% as compared to VITEK MS.All the isolates were susceptible to ceftazidime (n=46, 100%). Risk factors included diabetes mellitus (n=19, 41.3%) and indwelling devices such as central venous catheters (CVCs), urinary catheters, and mechanical ventilation. Recovery was seen in 40 (86.9%) patients on treatment with recommended antibiotics. Conclusion Our study shows that the identification of the genus Burkholderia by conventional biochemicals was as efficient as automated and molecular methods. Species identification of BCC was better with automated systems. Infections with BCC commonly occurred in patients with diabetes mellitus and indwelling d...