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<p>Diabetic foot ulcers (DFUs) are a leading cause of morbidity in patients with diabetes mellitus and a major driver of multidrug-resistant (MDR) bacterial infection in low- and middle-income countries. This cross-sectional study characterised the clinical profile, microbial spectrum and phenotypic/genotypic resistance patterns of DFU-associated bacteria in 224 patients recruited from six tertiary hospitals in Islamabad, Pakistan, between November 2023 and December 2024. Wound swabs, pus aspirates and deep tissue biopsies were collected aseptically and processed on selective and non-selective media; isolates were identified by colony morphology, Gram staining and standard biochemical tests with ATCC reference strains as controls. Antimicrobial susceptibility was determined by Kirby–Bauer disc diffusion against 15 antibiotics following CLSI M100 (2023) guidelines. Plasmid DNA was extracted from all phenotypically β-lactam– or aminoglycoside-resistant isolates and screened by PCR for β-lactamase genes (bla<i>TEM</i>, bla<i>CTX-M</i>, bla<i>SHV</i>) and aminoglycoside-modifying enzyme genes (aac(6′)-Ib, ant(4′)-Ia, aph(3′)-IIIa). Bacterial growth was obtained from 208/224 (92.9%) samples; six species were recovered: <i>Staphylococcus aureus</i> 41.3% (86/208), <i>Escherichia coli</i> 20.2% (42/208), <i>Staphylococcus epidermidis</i> 12.5% (26/208), <i>Proteus vulgaris</i> 10.6% (22/208), <i>Proteus mirabilis</i> 7.7% (16/208) and <i>Pseudomonas aeruginosa</i> 7.7% (16/208). Resistance to gentamicin was uniformly high (<i>S. aureus</i> 91.9%; <i>E. coli</i> 90.5%; <i>S. epidermidis</i> 84.6%); cefoperazone–sulbactam was the most active β-lactam against <i>S. aureus</i> (43.0% resistance) and colistin retained activity against <i>E. coli</i> (35.7% resistance). PCR detected aac(6′)-Ib in 114/208 (54.8%), bla<i>TEM</i> in 91/208 (43.8%), bla<i>CTX-M</i> in 83/208 (39.9%), bla<i>SHV</i> in 82/208 (39.4%), ant(4′)-Ia in 78/208 (37.5%) and aph(3′)-IIIa in 76/208 (36.5%) of isolates. Fisher’s exact test confirmed strong, statistically significant associations between aminoglycoside-modifying enzyme genes and gentamicin resistance, and between β-lactamase genes and cefotaxime resistance (specificity and positive predictive value = 100% at the reference antibiotic). DFUs in this Pakistani cohort were predominantly polymicrobial with a high burden of plasmid-mediated β-lactam and aminoglycoside resistance determinants. Strengthened antimicrobial stewardship, expanded molecular surveillance and patient-centred foot-care education are critical to reduce amputation risk and the public-health burden of DFU.</p>

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Clinical, phenotypic and genotypic antimicrobial resistance profile of diabetic foot ulcer–associated bacterial isolates

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年7月4日

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  • Awal Ayaz Khan,
  • Kaleem Imdad,
  • Jadoon Khan,
  • Muhammad Nadeem Khan,
  • Ijaz Ali,
  • Mutwakel Dabiellil,
  • Ahmed Al-Emam,
  • Hesham M. Hassan

摘要

Diabetic foot ulcers (DFUs) are a leading cause of morbidity in patients with diabetes mellitus and a major driver of multidrug-resistant (MDR) bacterial infection in low- and middle-income countries. This cross-sectional study characterised the clinical profile, microbial spectrum and phenotypic/genotypic resistance patterns of DFU-associated bacteria in 224 patients recruited from six tertiary hospitals in Islamabad, Pakistan, between November 2023 and December 2024. Wound swabs, pus aspirates and deep tissue biopsies were collected aseptically and processed on selective and non-selective media; isolates were identified by colony morphology, Gram staining and standard biochemical tests with ATCC reference strains as controls. Antimicrobial susceptibility was determined by Kirby–Bauer disc diffusion against 15 antibiotics following CLSI M100 (2023) guidelines. Plasmid DNA was extracted from all phenotypically β-lactam– or aminoglycoside-resistant isolates and screened by PCR for β-lactamase genes (blaTEM, blaCTX-M, blaSHV) and aminoglycoside-modifying enzyme genes (aac(6′)-Ib, ant(4′)-Ia, aph(3′)-IIIa). Bacterial growth was obtained from 208/224 (92.9%) samples; six species were recovered: Staphylococcus aureus 41.3% (86/208), Escherichia coli 20.2% (42/208), Staphylococcus epidermidis 12.5% (26/208), Proteus vulgaris 10.6% (22/208), Proteus mirabilis 7.7% (16/208) and Pseudomonas aeruginosa 7.7% (16/208). Resistance to gentamicin was uniformly high (S. aureus 91.9%; E. coli 90.5%; S. epidermidis 84.6%); cefoperazone–sulbactam was the most active β-lactam against S. aureus (43.0% resistance) and colistin retained activity against E. coli (35.7% resistance). PCR detected aac(6′)-Ib in 114/208 (54.8%), blaTEM in 91/208 (43.8%), blaCTX-M in 83/208 (39.9%), blaSHV in 82/208 (39.4%), ant(4′)-Ia in 78/208 (37.5%) and aph(3′)-IIIa in 76/208 (36.5%) of isolates. Fisher’s exact test confirmed strong, statistically significant associations between aminoglycoside-modifying enzyme genes and gentamicin resistance, and between β-lactamase genes and cefotaxime resistance (specificity and positive predictive value = 100% at the reference antibiotic). DFUs in this Pakistani cohort were predominantly polymicrobial with a high burden of plasmid-mediated β-lactam and aminoglycoside resistance determinants. Strengthened antimicrobial stewardship, expanded molecular surveillance and patient-centred foot-care education are critical to reduce amputation risk and the public-health burden of DFU.