Genetic Profiling of Raoultella spp. in Pediatric Clinical Samples: Insights from Bauchi, North East Nigeria

Abstract

Background: Raoultella species, are gram-negative bacteria of Enterobacteriaceae family, originally classified under Klebsiella, were reclassified in 2001 as a distinct genus. Members have emerged as notable pathogens, mostly in hospitalized and immunocompromised patients. Though once considered opportunistic, Raoultella spp. are now linked to various infections, including bacteremia, urinary tract infections, and neonatal sepsis, with antibiotic-resistant strains posing significant challenges in clinical settings. The true prevalence of Raoultella infections may be underreported due to diagnostic challenges, making early identification crucial for improved management in high-risk populations, particularly pediatrics. Raoultella species, emerging pathogens are increasingly linked to pediatric and neonatal infections in clinical settings. Aim: isolation and accurate identification of Raoultella species from pediatric clinical samples to address challenges in identification and genetic characterization. Study Design: This is a prospective, cross-sectional study involving pediatrics aged 0-5 years. Place and Duration of Study: Pioneering study in Bauchi, North-East Nigeria, from August 2021 to January 2022. Methodology: Samples from 262 pediatric patients with septicemia symptoms were processed at Abubakar Tafawa Balewa University Teaching Hospital (ATBUTH). The VITEK 2 Compact system was used for initial identification, while PCR amplification of the 16S rRNA gene confirmed Raoultella species. The genomic DNA of identified isolates underwent sequence and bioinformatics analysis. Results: The phylogenetic tree constructed using the 16S rRNA sequences of the isolates and reference strains visually represent the genetic relationships. The high homology observed in the sequence alignment is reflected in the phylogenetic clustering, with isolates RoP_2 (PQ213811), RoP_3 (PQ213812), and RoP_4 (PQ213813) grouping closely with known Raoultella planticola strains. This close genetic relationship further supports the species identification suggested by the gel electrophoresis and homology data. However, RoP_1 (PQ213810), identified as Proteus mirabilis through BLAST analysis of its 16S rRNA sequence, shows slightly lower homology with Raoultella planticola reference strains. In the phylogenetic tree, RoP_1 is positioned slightly apart from the other isolates, indicating some genetic variability. This discrepancy suggests that while RoP_1 shares characteristics with Raoultella, the distinct genetic makeup warrants further investigation to confirm its identification as R. planticola or otherwise. Conclusion: The phylogenetic analysis supports the identification of isolates RoP_2, RoP_3, and RoP_4 as Raoultella planticola, showing close genetic relationships. However, RoP_1 exhibits genetic variability, clustering separately and aligning more closely with Proteus mirabilis, suggesting the need for further investigation to confirm its species identification.