ANTIMICROBIAL PRESCRIBING PATTERNS IN COMPLICATED CELLULITIS: A PROSPECTIVE OBSERVATIONAL STUDY FROM A TERTIARY CARE TEACHING HOSPITAL IN KARNATAKA, INDIA

Objectives: To characterise the spectrum, frequency and route of antimicrobial agents prescribed for inpatients with cellulitis and its complications at a tertiary care teaching hospital; to document culture-identified multidrug-resistant (MDR) pathogen profiles; to quantify antimicrobial consumption using defined daily dose (DDD) methodology; and to identify clinical predictors of prolonged hospitalisation and intravenous antimicrobial use. Methods: A prospective observational study was conducted in the Department of Surgery, S.N.M.C. & H.S.K. Hospital and Research Centre, Bagalkot, Karnataka, India, over six months (February to August 2025). Forty consecutive inpatients with cellulitis and its complications were enrolled. Descriptive statistics, chi-square test and Fisher exact test were applied (p<0.05). Antimicrobial consumption was expressed as DDD per 100 bed-days using World Health Organisation (WHO) Anatomical Therapeutic Chemical (ATC)/DDD index 2023 values. Key Findings: The cohort comprised 34 males (85%) and 6 females (15%); 75% were aged 41 to 80 years and 75% had at least one comorbidity. Necrotising fasciitis constituted 45% of presentations; lower extremity involvement occurred in 90% of patients. Twenty-one antimicrobial agents were prescribed across 121 drug encounters (mean 3.02 per patient); 81% were administered intravenously. Piperacillin–tazobactam (18.03%), metronidazole (13.22%) and linezolid (10.74%) dominated prescribing. Among 14 patients (35%) with culture results, nine (64.3%) harboured MDR organisms — including extensively drug-resistant (XDR) Klebsiella pneumoniae, XDR Acinetobacter baumannii, methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE) — with tigecycline serving as the sole effective salvage agent across all five resistant pathogen categories simultaneously. Comorbidity was significantly associated with prolonged hospitalisation (χ²=8.523, df=3, p=0.036) and cellulitis severity significantly predicted intravenous route use (χ²=10.709, df=2, p=0.005). Conclusions: A critically high MDR pathogen burden drives heavy reliance on last-resort antimicrobials in this setting, with tigecycline functioning as the definitive salvage agent across multiple resistant pathogen categories simultaneously. Structured antimicrobial stewardship, universal pre-antibiotic culture sampling and evidence-based de-escalation protocols are urgently required.