Methods: The HCPCA chemical structure was determined using nuclear magnetic resonance spectroscopy. We conducted whole genome sequencing for the identification of the gene cluster(s) believed to be responsible for phenazine biosynthesis in order to map its corresponding pathway, in addition to bioinformatics analysis to assess the potential of S. kebangsaanensis in producing other useful secondary metabolites.
Results: The S. kebangsaanensis genome comprises an 8,328,719 bp linear chromosome with high GC content (71.35%) consisting of 12 rRNA operons, 81 tRNA, and 7,558 protein coding genes. We identified 24 gene clusters involved in polyketide, nonribosomal peptide, terpene, bacteriocin, and siderophore biosynthesis, as well as a gene cluster predicted to be responsible for phenazine biosynthesis.
Discussion: The HCPCA phenazine structure was hypothesized to derive from the combination of two biosynthetic pathways, phenazine-1,6-dicarboxylic acid and 4-methoxybenzene-1,2-diol, originated from the shikimic acid pathway. The identification of a biosynthesis pathway gene cluster for phenazine antibiotics might facilitate future genetic engineering design of new synthetic phenazine antibiotics. Additionally, these findings confirm the potential of S. kebangsaanensis for producing various antibiotics and secondary metabolites.
MATERIALS AND METHODS: A single-centre, prospective, casecontrol study involving 32 subjects of preterm neonates was conducted at a tertiary care hospital in Malang, East Java, Indonesia between January to June 2022. A total of 15 preterm neonates with NEC and 17 preterm neonates without NEC were enrolled in this study. Data on demographic, clinical and laboratory findings were collected. Multiple logistic regression test was performed to analyse the risk factors for NEC development. Further profiling within 15 subjects with NEC, i.e., NEC grade ≥ II, were conducted to collect systemic, abdominal, laboratory, abdominal x-ray (AXR) and blood culture findings.
RESULTS: The risk factors related to NEC development in preterm infants were multi-morbidity (adjusted OR = 11.96; 95% CI 1.85 168.38; p = 0.046), antibiotic exposure (OR = 15.95; 95% CI 1.54 165.08; p = 0.020) and requiring advanced neonatal resuscitation at birth (OR = 10.04; 95% CI 1.09 92.11; p = 0.041). Further profiling within NEC cohorts highlighted respiratory distress (86.7%), (oro)gastric retention (80.0%), thrombocytopenia (53.3%), gastrointestinal dilatation in AXR (53.3%), and positive blood culture Klebsiella pneumoniae (40.0%) were most common findings.
CONCLUSION: Preterm neonates with multimorbidity, prolonged antibiotic exposure, and requiring advanced resuscitation at birth were more likely to develop NEC. Early detection of the risk factors and determinant factors for survival may help to improve the clinical outcome.