Burden and Trends of Antimicrobial Non-susceptibility in Skin and Soft Tissue Infections: Nine-Year Microbiological Surveillance from a Tertiary Hospital in Riyadh, Saudi Arabia

Yahya Shabi^1*Abdullah A. Alshehri²Khalifa Binkhamis³Mohammed Alqahtani⁴Thamir Saad Alsaeed⁵Ali Abdullah Aljaberi²Saleh Abdullah Alkhamis²Mohammad K. Alshomrani²Abdullah Z. Almutairi²Fatimah Alshahrani⁶Abdulah Alqahtani¹Ahmad Jebril M. Bosaily⁷

• ¹Department of Microbiology and Clinical Parasitology, College of Medicine, King Khalid University, Abha, Saudi Arabia
• ²microbiology laboratory, prince mohammed bin abdulaziiz, riyadh, saudi arabia, riyadh, Saudi Arabia
• ³department of pathology, college of medicine, king saud university,, riyadh, Saudi Arabia
• ⁴microbiology section, pathology and medical laboratories department and blood banks, security forces hospitals, riyadh, Saudi Arabia
• ⁵Qassim University, Buraydah, Saudi Arabia
• ⁶College of Medicine, King Saud University, riyadh, Saudi Arabia
• ⁷General surgery department, college of medicine, king khalid university, abha, Saudi Arabia

Background Skin and soft tissue infections (SSTIs) impose a substantial global and regional burden, and their management is increasingly complicated by antimicrobial non-susceptibility. In Saudi Arabia, data remain fragmented, with few studies providing species-level analyses stratified by specimen type and infection depth. Methods We retrospectively analyzed 6,760 wound and tissue specimens (2016-2024) from a tertiary hospital in Riyadh, Saudi Arabia. Organisms were identified using standard microbiological methods and VITEK 2. Antimicrobial susceptibility testing was interpreted according to CLSI M100, defining non-susceptibility as resistant or intermediate categories. Binary logistic regression was used to assess temporal trends in antimicrobial non-susceptibility, with year of isolation entered as a continuous predictor. Results Gram-negative organisms predominated (63.2%), followed by Gram-positives (35.6%) and yeast (1.2%). Staphylococcus aureus was the leading pathogen (28.8%), with methicillin resistance detected in 39.0% of isolates. Escherichia coli (14.7%) and Pseudomonas aeruginosa (12.1%) were also common. Among Enterobacterales, 26.9% were extended-spectrum β-lactamase (ESBL) producers and 16.1% were carbapenem-resistant Enterobacterales (CRE). P. aeruginosa showed high carbapenem non-susceptibility. Tissue-derived isolates demonstrated significantly higher meropenem non-susceptibility than swab Isolates (20.3% vs. 16.4%, p = 0.027), although Enterobacterales subsets occasionally showed the reverse pattern. Temporal analysis revealed rising non-susceptibility to amikacin, ceftriaxone, imipenem, and meropenem (p < 0.05), while oxacillin resistance in S. aureus and clindamycin non-susceptibility in Gram-positives declined over time. Conclusion Gram-negative organisms predominated in SSTIs, showing rising non-susceptibility to amikacin and carbapenems. Separately, among Gram-positive pathogens, Staphylococcus aureus exhibited a clear decline in oxacillin resistance. These shifts underscore the need for ongoing resistance surveillance.