Beyond Staphylococcus aureus: emerging Gram-negative isolates in pediatric impetigo in Southern Vietnam

Impetigo is common in tropical regions, yet local data on bacterial spectra beyond Staphylococcus aureus remain limited. This study aimed to characterize clinical features, bacterial isolates, and resistance-related factors among patients with impetigo in the Mekong Delta, Vietnam. We conducted a prospective cross-sectional study of 74 patients with clinically diagnosed impetigo at Can Tho City Hospital of Dermato-Venereology from May 2020 to July 2022. Demographic and clinical data were collected using a standardized form. Lesion swabs were cultured, isolates were identified by conventional microbiological methods, and antimicrobial susceptibility was assessed by disk diffusion according to Clinical and Laboratory Standards Institute procedures. Disease severity was evaluated using the Skin Infection Rating Scale (SIRS). The mean age was 4.4±3.5 years; 58.1% of patients were aged 2-6 years. Non-bullous impetigo was the predominant subtype (71.6%), and most patients presented with moderate or severe disease. Cultures were positive in 43 patients (58.0%). S. aureus was the leading pathogen (79.1%), followed by Escherichia coli (11.7%), Staphylococcus species (4.6%), Pseudomonas aeruginosa (2.3%), and Proteus spp. (2.3%). No Streptococcus pyogenes was isolated. E. coli was detected in ecthyma and showed high resistance to antibiotic classes, including universal resistance to levofloxacin and piperacillin/tazobactam. No statistically significant association was found between S. aureus resistance and clinical subtype, baseline severity, prior antibiotic exposure, or disease duration. Impetigo in this setting was predominantly pediatric and S. aureus-associated; however, Gram-negative organisms, especially E. coli, may contribute to severe or ulcerative disease. Culture and susceptibility testing should be considered in complicated cases.