Microbiological profile, antimicrobial resistance, and factors associated with ulcer severity in diabetic foot infections: a multicentre cross-sectional study from Khyber Pakhtunkhwa, Pakistan

Diabetic foot infections (DFIs) cause hospitalisation, limb loss, and substantial antimicrobial use, but microbiology and resistance vary geographically. Contemporary multicentre data from Pakistan are limited. We characterised the microbial spectrum, susceptibility, key resistance phenotypes, and factors associated with ulcer severity. We conducted a multicentre cross-sectional study at four centres in three districts of Khyber Pakhtunkhwa, Pakistan (October 2025–June 2026). Consecutive adults with clinically diagnosed, culture-positive DFI were enrolled. Severe ulceration was defined as Wagner grade ≥ 3; IWGDF/IDSA infection severity was unavailable. Associations were assessed with multivariable logistic regression. Of 190 patients screened, 170 were included. Gram-negative organisms comprised 101/170 (59.4%) primary isolates; Escherichia coli , Klebsiella pneumoniae , and Pseudomonas aeruginosa were most common. The presumptive ESBL surrogate was present in 59/76 (77.6%) Enterobacterales . Organism-restricted carbapenem resistance was 18/99 (18.2%); any recorded resistant carbapenem result occurred in 25/110 records (22.7%). MRSA accounted for 17/54 (31.5%) Staphylococcus aureus isolates. Among the 101 Gram-negative primary isolates, meropenem was the most active agent (86/101, 85.1%); linezolid and vancomycin were most active against Gram-positive isolates. Amikacin (66/97, 68.0%) and piperacillin/tazobactam (65/101, 64.4%) each left approximately one third of tested Gram-negative isolates non-susceptible. Ischaemia (adjusted odds ratio [aOR] 3.05, 95% confidence interval [CI] 1.49–6.23) and HbA1c (aOR 1.50 per 1%, 95% CI 1.08–2.09) were independently associated with severe ulceration; ischaemia remained associated after excluding gangrenous ulcers. DFIs were predominantly Gram-negative, with high third-generation cephalosporin resistance and substantial carbapenem resistance. Ulcer severity was associated with ischaemia and poor glycaemic control. Findings support locally informed empirical therapy, rapid culture-guided de-escalation, vascular assessment, glycaemic optimisation, timely source control, and strengthened stewardship.