On 12 May 2026, at VNUHCM–University of Science (HCMUS), doctoral researcher Lê Thị Nga successfully defended a doctoral thesis in Microbiology. The research, titled “The prevalence of antibiotic resistance and characteristics of colistin resistance in enteric bacteria isolated from faecal samples of paediatric patients with diarrhoea in Southern Viet Nam”, was supervised by Associate Professor Phan Thị Phượng Trang and Dr Hoàng Hoài Phương.

Antimicrobial resistance represents one of the pre-eminent challenges to global public health, particularly regarding the clinical management of infections caused by multi-drug resistant Gram-negative bacteria. Consequently, colistin—a polymyxin antibiotic—serves as a treatment of last resort for numerous severe infections. Nevertheless, the emergence and dissemination of colistin resistance genes within the mcr family pose significant hurdles to therapeutic efficacy.

Driven by these clinical realities, the thesis investigates the status of antibiotic resistance and the specific mechanisms of colistin resistance in enteric bacteria isolated from paediatric patients aged five and under suffering from diarrhoea in Southern Viet Nam. The study involved isolating Enterobacteriaceae strains, performing antibiotic susceptibility testing, determining minimum inhibitory concentrations (MIC) for colistin, and identifying mcr genes via PCR techniques.

The findings indicate variations in colistin resistance rates across different groups of enteric bacteria, with E. coli and Klebsiella spp. exhibiting the highest prevalence. Furthermore, the research identified mcr-1, mcr-8, and mcr-9 gene variants within the isolates, providing clarity on the transmission dynamics of colistin resistance genes within microbial populations.

In addition, the thesis analysed the molecular genetic characteristics of mcr genes and evaluated the capacity for horizontal gene transfer through conjugation experiments. These results contribute essential data towards the establishment of a molecular surveillance system for colistin resistance genes in Viet Nam, specifically targeting children under five—a demographic characterised by immature immune systems and developing gut microbiota.

During the doctoral candidature, doctoral researcher Lê Thị Nga published three international papers indexed in Scopus and one national scientific paper presented at the National Conference on Biology.

The examiners commended the thesis for timeliness, scientific rigour, and originality. This work provides vital data to inform the ongoing study and monitoring of antibiotic resistance in paediatric enteric bacteria within the Vietnamese context.