To evaluate MRSA infections with a specific focus on heterogeneous vancomycin-intermediate Staphylococcus aureus (hVISA) among patients with and without diabetes mellitus, and to assess differences between these two populations.Isolated S. aureus strains from diabetic and non-diabetic inpatients across four tertiary hospitals in Coastal Karnataka (South India) were assessed for methicillin resistance and enrolled in the study. Patient-related demographic and clinical information was obtained through a standardized data collection form. Antimicrobial susceptibility testing was conducted using the Kirby–Bauer disk diffusion method. Detection of macrolide–lincosamide–streptogramin B (MLSb) resistance was performed using the D-test. Vancomycin minimum inhibitory concentrations were measured by agar dilution. MRSA isolates were further evaluated for heterogeneous vancomycin-intermediate S. aureus (hVISA) using vancomycin screening agar, with confirmation by population analysis profile–area under the curve (PAP-AUC). Statistical evaluation was performed using the chi-square test, and all analyses were conducted in SPSS version 29.0.Among 665 S. aureus isolates, 220 (33.1%) were identified as MRSA. Of these, 122 (55.5%) originated from diabetic patients, while 98 (44.5%) were from non-diabetic patients. No significant differences in antimicrobial resistance profiles were observed between MRSA isolates from the two patient groups. However, MRSA-associated foot infections and osteomyelitis were significantly more frequent in diabetic patients. Among the 220 MRSA isolates, 14 (6.4%) were classified as hVISA. The prevalence of hVISA was 9.0% in isolates from diabetic patients and 3.1% in those from non-diabetic patients; however, this difference did not reach statistical significance. Overall, 6.4% of all MRSA isolates were classified as hVISA. The likelihood of hVISA was about three times higher in patients with diabetes than in those without. These results underscore the need to target screening for hVISA among MRSA strains, especially in diabetic individuals.
